/*- * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra. * Copyright 2003 Alexander Kabaev . * Copyright 2009-2012 Konstantin Belousov . * Copyright 2012 John Marino . * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * $FreeBSD$ */ /* * Dynamic linker for ELF. * * John Polstra . */ #ifndef __GNUC__ #error "GCC is needed to compile this file" #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "debug.h" #include "rtld.h" #include "libmap.h" #include "rtld_printf.h" #include "notes.h" #define cpu_sfence() __asm __volatile("" : : : "memory"); #define PATH_RTLD "/usr/libexec/ld-elf.so.2" #define LD_ARY_CACHE 16 /* Types. */ typedef void (*func_ptr_type)(); typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg); /* * Function declarations. */ static int __getstatictlsextra(void); static const char *_getenv_ld(const char *id); static void die(void) __dead2; static void digest_dynamic1(Obj_Entry *, int, const Elf_Dyn **, const Elf_Dyn **, const Elf_Dyn **); static void digest_dynamic2(Obj_Entry *, const Elf_Dyn *, const Elf_Dyn *, const Elf_Dyn *); static void digest_dynamic(Obj_Entry *, int); static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *); static void distribute_static_tls(Objlist *, RtldLockState *); static Obj_Entry *dlcheck(void *); static Obj_Entry *dlopen_object(const char *name, int fd, Obj_Entry *refobj, int lo_flags, int mode, RtldLockState *lockstate); static Obj_Entry *do_load_object(int, const char *, char *, struct stat *, int); static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *); static bool donelist_check(DoneList *, const Obj_Entry *); static void errmsg_restore(char *); static char *errmsg_save(void); static void *fill_search_info(const char *, size_t, void *); static char *find_library(const char *, const Obj_Entry *, int *); static const char *gethints(bool); static void init_dag(Obj_Entry *); static void init_rtld(caddr_t, Elf_Auxinfo **); static void initlist_add_neededs(Needed_Entry *, Objlist *); static void initlist_add_objects(Obj_Entry *, Obj_Entry **, Objlist *); static void linkmap_add(Obj_Entry *); static void linkmap_delete(Obj_Entry *); static void load_filtees(Obj_Entry *, int flags, RtldLockState *); static void unload_filtees(Obj_Entry *); static int load_needed_objects(Obj_Entry *, int); static int load_preload_objects(void); static Obj_Entry *load_object(const char *, int fd, const Obj_Entry *, int); static void map_stacks_exec(RtldLockState *); static Obj_Entry *obj_from_addr(const void *); static void objlist_call_fini(Objlist *, Obj_Entry *, RtldLockState *); static void objlist_call_init(Objlist *, RtldLockState *); static void objlist_clear(Objlist *); static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *); static void objlist_init(Objlist *); static void objlist_push_head(Objlist *, Obj_Entry *); static void objlist_push_tail(Objlist *, Obj_Entry *); static void objlist_put_after(Objlist *, Obj_Entry *, Obj_Entry *); static void objlist_remove(Objlist *, Obj_Entry *); static int parse_libdir(const char *); static void *path_enumerate(const char *, path_enum_proc, void *); static int relocate_object_dag(Obj_Entry *root, bool bind_now, Obj_Entry *rtldobj, int flags, RtldLockState *lockstate); static int relocate_object(Obj_Entry *obj, bool bind_now, Obj_Entry *rtldobj, int flags, RtldLockState *lockstate); static int relocate_objects(Obj_Entry *, bool, Obj_Entry *, int, RtldLockState *); static int resolve_objects_ifunc(Obj_Entry *first, bool bind_now, int flags, RtldLockState *lockstate); static int rtld_dirname(const char *, char *); static int rtld_dirname_abs(const char *, char *); static void *rtld_dlopen(const char *name, int fd, int mode); static void rtld_exit(void); static char *search_library_path(const char *, const char *); static char *search_library_pathfds(const char *, const char *, int *); static const void **get_program_var_addr(const char *, RtldLockState *); static void set_program_var(const char *, const void *); static int symlook_default(SymLook *, const Obj_Entry *refobj); static int symlook_global(SymLook *, DoneList *); static void symlook_init_from_req(SymLook *, const SymLook *); static int symlook_list(SymLook *, const Objlist *, DoneList *); static int symlook_needed(SymLook *, const Needed_Entry *, DoneList *); static int symlook_obj1_sysv(SymLook *, const Obj_Entry *); static int symlook_obj1_gnu(SymLook *, const Obj_Entry *); static void trace_loaded_objects(Obj_Entry *); static void unlink_object(Obj_Entry *); static void unload_object(Obj_Entry *); static void unref_dag(Obj_Entry *); static void ref_dag(Obj_Entry *); static char *origin_subst_one(char *, const char *, const char *, bool); static char *origin_subst(char *, const char *); static void preinit_main(void); static int rtld_verify_versions(const Objlist *); static int rtld_verify_object_versions(Obj_Entry *); static void object_add_name(Obj_Entry *, const char *); static int object_match_name(const Obj_Entry *, const char *); static void ld_utrace_log(int, void *, void *, size_t, int, const char *); static void rtld_fill_dl_phdr_info(const Obj_Entry *obj, struct dl_phdr_info *phdr_info); static uint_fast32_t gnu_hash (const char *); static bool matched_symbol(SymLook *, const Obj_Entry *, Sym_Match_Result *, const unsigned long); void r_debug_state(struct r_debug *, struct link_map *) __noinline; void _r_debug_postinit(struct link_map *) __noinline; /* * Data declarations. */ static char *error_message; /* Message for dlerror(), or NULL */ struct r_debug r_debug; /* for GDB; */ static bool libmap_disable; /* Disable libmap */ static bool ld_loadfltr; /* Immediate filters processing */ static char *libmap_override; /* Maps to use in addition to libmap.conf */ static bool trust; /* False for setuid and setgid programs */ static bool dangerous_ld_env; /* True if environment variables have been used to affect the libraries loaded */ static const char *ld_bind_now; /* Environment variable for immediate binding */ static const char *ld_debug; /* Environment variable for debugging */ static const char *ld_library_path; /* Environment variable for search path */ static const char *ld_library_dirs; /* Env variable for library descriptors */ static char *ld_preload; /* Environment variable for libraries to load first */ static const char *ld_elf_hints_path; /* Env var. for alternative hints path */ static const char *ld_tracing; /* Called from ldd to print libs */ static const char *ld_utrace; /* Use utrace() to log events. */ static int (*rtld_functrace)( /* Optional function call tracing hook */ const char *caller_obj, const char *callee_obj, const char *callee_func, void *stack); static const Obj_Entry *rtld_functrace_obj; /* Object thereof */ static Obj_Entry *obj_list; /* Head of linked list of shared objects */ static Obj_Entry **obj_tail; /* Link field of last object in list */ static Obj_Entry **preload_tail; static Obj_Entry *obj_main; /* The main program shared object */ static Obj_Entry obj_rtld; /* The dynamic linker shared object */ static unsigned int obj_count; /* Number of objects in obj_list */ static unsigned int obj_loads; /* Number of objects in obj_list */ static int ld_resident; /* Non-zero if resident */ static const char *ld_ary[LD_ARY_CACHE]; static int ld_index; static Objlist initlist; static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */ STAILQ_HEAD_INITIALIZER(list_global); static Objlist list_main = /* Objects loaded at program startup */ STAILQ_HEAD_INITIALIZER(list_main); static Objlist list_fini = /* Objects needing fini() calls */ STAILQ_HEAD_INITIALIZER(list_fini); static Elf_Sym sym_zero; /* For resolving undefined weak refs. */ const char *__ld_sharedlib_base; #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m); extern Elf_Dyn _DYNAMIC; #pragma weak _DYNAMIC #ifndef RTLD_IS_DYNAMIC #define RTLD_IS_DYNAMIC() (&_DYNAMIC != NULL) #endif #ifdef ENABLE_OSRELDATE int osreldate; #endif static int stack_prot = PROT_READ | PROT_WRITE | RTLD_DEFAULT_STACK_EXEC; #if 0 static int max_stack_flags; #endif /* * Global declarations normally provided by crt1. The dynamic linker is * not built with crt1, so we have to provide them ourselves. */ char *__progname; char **environ; /* * Used to pass argc, argv to init functions. */ int main_argc; char **main_argv; /* * Globals to control TLS allocation. */ size_t tls_last_offset; /* Static TLS offset of last module */ size_t tls_last_size; /* Static TLS size of last module */ size_t tls_static_space; /* Static TLS space allocated */ int tls_dtv_generation = 1; /* Used to detect when dtv size changes */ int tls_max_index = 1; /* Largest module index allocated */ /* * Fill in a DoneList with an allocation large enough to hold all of * the currently-loaded objects. Keep this as a macro since it calls * alloca and we want that to occur within the scope of the caller. */ #define donelist_init(dlp) \ ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \ assert((dlp)->objs != NULL), \ (dlp)->num_alloc = obj_count, \ (dlp)->num_used = 0) #define UTRACE_DLOPEN_START 1 #define UTRACE_DLOPEN_STOP 2 #define UTRACE_DLCLOSE_START 3 #define UTRACE_DLCLOSE_STOP 4 #define UTRACE_LOAD_OBJECT 5 #define UTRACE_UNLOAD_OBJECT 6 #define UTRACE_ADD_RUNDEP 7 #define UTRACE_PRELOAD_FINISHED 8 #define UTRACE_INIT_CALL 9 #define UTRACE_FINI_CALL 10 struct utrace_rtld { char sig[4]; /* 'RTLD' */ int event; void *handle; void *mapbase; /* Used for 'parent' and 'init/fini' */ size_t mapsize; int refcnt; /* Used for 'mode' */ char name[MAXPATHLEN]; }; #define LD_UTRACE(e, h, mb, ms, r, n) do { \ if (ld_utrace != NULL) \ ld_utrace_log(e, h, mb, ms, r, n); \ } while (0) static void ld_utrace_log(int event, void *handle, void *mapbase, size_t mapsize, int refcnt, const char *name) { struct utrace_rtld ut; ut.sig[0] = 'R'; ut.sig[1] = 'T'; ut.sig[2] = 'L'; ut.sig[3] = 'D'; ut.event = event; ut.handle = handle; ut.mapbase = mapbase; ut.mapsize = mapsize; ut.refcnt = refcnt; bzero(ut.name, sizeof(ut.name)); if (name) strlcpy(ut.name, name, sizeof(ut.name)); utrace(&ut, sizeof(ut)); } /* * Main entry point for dynamic linking. The first argument is the * stack pointer. The stack is expected to be laid out as described * in the SVR4 ABI specification, Intel 386 Processor Supplement. * Specifically, the stack pointer points to a word containing * ARGC. Following that in the stack is a null-terminated sequence * of pointers to argument strings. Then comes a null-terminated * sequence of pointers to environment strings. Finally, there is a * sequence of "auxiliary vector" entries. * * The second argument points to a place to store the dynamic linker's * exit procedure pointer and the third to a place to store the main * program's object. * * The return value is the main program's entry point. */ func_ptr_type _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp) { Elf_Auxinfo *aux_info[AT_COUNT]; int i; int argc; char **argv; char **env; Elf_Auxinfo *aux; Elf_Auxinfo *auxp; const char *argv0; Objlist_Entry *entry; Obj_Entry *obj; Obj_Entry *last_interposer; /* marino: DO NOT MOVE THESE VARIABLES TO _rtld Obj_Entry **preload_tail; Objlist initlist; from global to here. It will break the DWARF2 unwind scheme. */ /* * On entry, the dynamic linker itself has not been relocated yet. * Be very careful not to reference any global data until after * init_rtld has returned. It is OK to reference file-scope statics * and string constants, and to call static and global functions. */ /* Find the auxiliary vector on the stack. */ argc = *sp++; argv = (char **) sp; sp += argc + 1; /* Skip over arguments and NULL terminator */ env = (char **) sp; /* * If we aren't already resident we have to dig out some more info. * Note that auxinfo does not exist when we are resident. * * I'm not sure about the ld_resident check. It seems to read zero * prior to relocation, which is what we want. When running from a * resident copy everything will be relocated so we are definitely * good there. */ if (ld_resident == 0) { while (*sp++ != 0) /* Skip over environment, and NULL terminator */ ; aux = (Elf_Auxinfo *) sp; /* Digest the auxiliary vector. */ for (i = 0; i < AT_COUNT; i++) aux_info[i] = NULL; for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { if (auxp->a_type < AT_COUNT) aux_info[auxp->a_type] = auxp; } /* Initialize and relocate ourselves. */ assert(aux_info[AT_BASE] != NULL); init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr, aux_info); } ld_index = 0; /* don't use old env cache in case we are resident */ __progname = obj_rtld.path; argv0 = argv[0] != NULL ? argv[0] : "(null)"; environ = env; main_argc = argc; main_argv = argv; trust = !issetugid(); ld_bind_now = _getenv_ld("LD_BIND_NOW"); /* * If the process is tainted, then we un-set the dangerous environment * variables. The process will be marked as tainted until setuid(2) * is called. If any child process calls setuid(2) we do not want any * future processes to honor the potentially un-safe variables. */ if (!trust) { if ( unsetenv("LD_DEBUG") || unsetenv("LD_PRELOAD") || unsetenv("LD_LIBRARY_PATH") || unsetenv("LD_LIBRARY_PATH_FDS") || unsetenv("LD_ELF_HINTS_PATH") || unsetenv("LD_LIBMAP") || unsetenv("LD_LIBMAP_DISABLE") || unsetenv("LD_LOADFLTR") || unsetenv("LD_SHAREDLIB_BASE") ) { _rtld_error("environment corrupt; aborting"); die(); } } __ld_sharedlib_base = _getenv_ld("LD_SHAREDLIB_BASE"); ld_debug = _getenv_ld("LD_DEBUG"); libmap_disable = _getenv_ld("LD_LIBMAP_DISABLE") != NULL; libmap_override = (char *)_getenv_ld("LD_LIBMAP"); ld_library_path = _getenv_ld("LD_LIBRARY_PATH"); ld_library_dirs = _getenv_ld("LD_LIBRARY_PATH_FDS"); ld_preload = (char *)_getenv_ld("LD_PRELOAD"); ld_elf_hints_path = _getenv_ld("LD_ELF_HINTS_PATH"); ld_loadfltr = _getenv_ld("LD_LOADFLTR") != NULL; dangerous_ld_env = (ld_library_path != NULL) || (ld_preload != NULL) || (ld_elf_hints_path != NULL) || ld_loadfltr || (libmap_override != NULL) || libmap_disable ; ld_tracing = _getenv_ld("LD_TRACE_LOADED_OBJECTS"); ld_utrace = _getenv_ld("LD_UTRACE"); if ((ld_elf_hints_path == NULL) || strlen(ld_elf_hints_path) == 0) ld_elf_hints_path = _PATH_ELF_HINTS; if (ld_debug != NULL && *ld_debug != '\0') debug = 1; dbg("%s is initialized, base address = %p", __progname, (caddr_t) aux_info[AT_BASE]->a_un.a_ptr); dbg("RTLD dynamic = %p", obj_rtld.dynamic); dbg("RTLD pltgot = %p", obj_rtld.pltgot); dbg("initializing thread locks"); lockdflt_init(); /* * If we are resident we can skip work that we have already done. * Note that the stack is reset and there is no Elf_Auxinfo * when running from a resident image, and the static globals setup * between here and resident_skip will have already been setup. */ if (ld_resident) goto resident_skip1; /* * Load the main program, or process its program header if it is * already loaded. */ if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */ int fd = aux_info[AT_EXECFD]->a_un.a_val; dbg("loading main program"); obj_main = map_object(fd, argv0, NULL); close(fd); if (obj_main == NULL) die(); #if 0 max_stack_flags = obj_main->stack_flags; #endif } else { /* Main program already loaded. */ const Elf_Phdr *phdr; int phnum; caddr_t entry; dbg("processing main program's program header"); assert(aux_info[AT_PHDR] != NULL); phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr; assert(aux_info[AT_PHNUM] != NULL); phnum = aux_info[AT_PHNUM]->a_un.a_val; assert(aux_info[AT_PHENT] != NULL); assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr)); assert(aux_info[AT_ENTRY] != NULL); entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr; if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL) die(); } char buf[MAXPATHLEN]; if (aux_info[AT_EXECPATH] != NULL) { char *kexecpath; kexecpath = aux_info[AT_EXECPATH]->a_un.a_ptr; dbg("AT_EXECPATH %p %s", kexecpath, kexecpath); if (kexecpath[0] == '/') obj_main->path = kexecpath; else if (getcwd(buf, sizeof(buf)) == NULL || strlcat(buf, "/", sizeof(buf)) >= sizeof(buf) || strlcat(buf, kexecpath, sizeof(buf)) >= sizeof(buf)) obj_main->path = xstrdup(argv0); else obj_main->path = xstrdup(buf); } else { char resolved[MAXPATHLEN]; dbg("No AT_EXECPATH"); if (argv0[0] == '/') { if (realpath(argv0, resolved) != NULL) obj_main->path = xstrdup(resolved); else obj_main->path = xstrdup(argv0); } else { if (getcwd(buf, sizeof(buf)) != NULL && strlcat(buf, "/", sizeof(buf)) < sizeof(buf) && strlcat(buf, argv0, sizeof (buf)) < sizeof(buf) && access(buf, R_OK) == 0 && realpath(buf, resolved) != NULL) obj_main->path = xstrdup(resolved); else obj_main->path = xstrdup(argv0); } } dbg("obj_main path %s", obj_main->path); obj_main->mainprog = true; if (aux_info[AT_STACKPROT] != NULL && aux_info[AT_STACKPROT]->a_un.a_val != 0) stack_prot = aux_info[AT_STACKPROT]->a_un.a_val; /* * Get the actual dynamic linker pathname from the executable if * possible. (It should always be possible.) That ensures that * gdb will find the right dynamic linker even if a non-standard * one is being used. */ if (obj_main->interp != NULL && strcmp(obj_main->interp, obj_rtld.path) != 0) { free(obj_rtld.path); obj_rtld.path = xstrdup(obj_main->interp); __progname = obj_rtld.path; } digest_dynamic(obj_main, 0); dbg("%s valid_hash_sysv %d valid_hash_gnu %d dynsymcount %d", obj_main->path, obj_main->valid_hash_sysv, obj_main->valid_hash_gnu, obj_main->dynsymcount); linkmap_add(obj_main); linkmap_add(&obj_rtld); /* Link the main program into the list of objects. */ *obj_tail = obj_main; obj_tail = &obj_main->next; obj_count++; obj_loads++; /* Initialize a fake symbol for resolving undefined weak references. */ sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE); sym_zero.st_shndx = SHN_UNDEF; sym_zero.st_value = -(uintptr_t)obj_main->relocbase; if (!libmap_disable) libmap_disable = (bool)lm_init(libmap_override); dbg("loading LD_PRELOAD libraries"); if (load_preload_objects() == -1) die(); preload_tail = obj_tail; dbg("loading needed objects"); if (load_needed_objects(obj_main, 0) == -1) die(); /* Make a list of all objects loaded at startup. */ last_interposer = obj_main; for (obj = obj_list; obj != NULL; obj = obj->next) { if (obj->z_interpose && obj != obj_main) { objlist_put_after(&list_main, last_interposer, obj); last_interposer = obj; } else { objlist_push_tail(&list_main, obj); } obj->refcount++; } dbg("checking for required versions"); if (rtld_verify_versions(&list_main) == -1 && !ld_tracing) die(); resident_skip1: if (ld_tracing) { /* We're done */ trace_loaded_objects(obj_main); exit(0); } if (ld_resident) /* XXX clean this up! */ goto resident_skip2; if (_getenv_ld("LD_DUMP_REL_PRE") != NULL) { dump_relocations(obj_main); exit (0); } /* setup TLS for main thread */ dbg("initializing initial thread local storage"); STAILQ_FOREACH(entry, &list_main, link) { /* * Allocate all the initial objects out of the static TLS * block even if they didn't ask for it. */ allocate_tls_offset(entry->obj); } /* * Calculate the size of the TLS static segment. This is allocated * for every thread. Generally make it page-aligned for efficiency, * but take into account the fact that the actual allocation also * includes room for the struct tls_tcb header. */ { ssize_t space; ssize_t extra; extra = __getstatictlsextra(); space = tls_last_offset + extra + sizeof(struct tls_tcb); space = (space + PAGE_SIZE - 1) & ~((ssize_t)PAGE_SIZE - 1); tls_static_space = (size_t)space - sizeof(struct tls_tcb); } /* * Do not try to allocate the TLS here, let libc do it itself. * (crt1 for the program will call _init_tls()) */ if (relocate_objects(obj_main, ld_bind_now != NULL && *ld_bind_now != '\0', &obj_rtld, SYMLOOK_EARLY, NULL) == -1) die(); dbg("doing copy relocations"); if (do_copy_relocations(obj_main) == -1) die(); resident_skip2: if (_getenv_ld("LD_RESIDENT_UNREGISTER_NOW")) { if (exec_sys_unregister(-1) < 0) { dbg("exec_sys_unregister failed %d\n", errno); exit(errno); } dbg("exec_sys_unregister success\n"); exit(0); } if (_getenv_ld("LD_DUMP_REL_POST") != NULL) { dump_relocations(obj_main); exit (0); } dbg("initializing key program variables"); set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : ""); set_program_var("environ", env); set_program_var("__elf_aux_vector", aux); if (_getenv_ld("LD_RESIDENT_REGISTER_NOW")) { extern void resident_start(void); ld_resident = 1; if (exec_sys_register(resident_start) < 0) { dbg("exec_sys_register failed %d\n", errno); exit(errno); } dbg("exec_sys_register success\n"); exit(0); } /* Make a list of init functions to call. */ objlist_init(&initlist); initlist_add_objects(obj_list, preload_tail, &initlist); r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */ map_stacks_exec(NULL); dbg("resolving ifuncs"); { RtldLockState lockstate; wlock_acquire(rtld_bind_lock, &lockstate); if (resolve_objects_ifunc( obj_main, (ld_bind_now != NULL && *ld_bind_now != '\0'), SYMLOOK_EARLY, &lockstate) == -1) { die(); } lock_release(rtld_bind_lock, &lockstate); } /* * Do NOT call the initlist here, give libc a chance to set up * the initial TLS segment. crt1 will then call _rtld_call_init(). */ dbg("transferring control to program entry point = %p", obj_main->entry); /* Return the exit procedure and the program entry point. */ *exit_proc = rtld_exit; *objp = obj_main; return (func_ptr_type) obj_main->entry; } /* * Call the initialization list for dynamically loaded libraries. * (called from crt1.c). */ void _rtld_call_init(void) { RtldLockState lockstate; Obj_Entry *obj; if (!obj_main->note_present && obj_main->valid_hash_gnu) { /* * The use of a linker script with a PHDRS directive that does not include * PT_NOTE will block the crt_no_init note. In this case we'll look for the * recently added GNU hash dynamic tag which gets built by default. It is * extremely unlikely to find a pre-3.1 binary without a PT_NOTE header and * a gnu hash tag. If gnu hash found, consider binary to use new crt code. */ obj_main->crt_no_init = true; dbg("Setting crt_no_init without presence of PT_NOTE header"); } wlock_acquire(rtld_bind_lock, &lockstate); if (obj_main->crt_no_init) preinit_main(); else { /* * Make sure we don't call the main program's init and fini functions * for binaries linked with old crt1 which calls _init itself. */ obj_main->init = obj_main->fini = (Elf_Addr)NULL; obj_main->init_array = obj_main->fini_array = (Elf_Addr)NULL; } objlist_call_init(&initlist, &lockstate); _r_debug_postinit(&obj_main->linkmap); objlist_clear(&initlist); dbg("loading filtees"); for (obj = obj_list->next; obj != NULL; obj = obj->next) { if (ld_loadfltr || obj->z_loadfltr) load_filtees(obj, 0, &lockstate); } lock_release(rtld_bind_lock, &lockstate); } void * rtld_resolve_ifunc(const Obj_Entry *obj, const Elf_Sym *def) { void *ptr; Elf_Addr target; ptr = (void *)make_function_pointer(def, obj); target = ((Elf_Addr (*)(void))ptr)(); return ((void *)target); } Elf_Addr _rtld_bind(Obj_Entry *obj, Elf_Size reloff, void *stack) { const Elf_Rel *rel; const Elf_Sym *def; const Obj_Entry *defobj; Elf_Addr *where; Elf_Addr target; RtldLockState lockstate; rlock_acquire(rtld_bind_lock, &lockstate); if (sigsetjmp(lockstate.env, 0) != 0) lock_upgrade(rtld_bind_lock, &lockstate); if (obj->pltrel) rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff); else rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff); where = (Elf_Addr *) (obj->relocbase + rel->r_offset); def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL, &lockstate); if (def == NULL) die(); if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) target = (Elf_Addr)rtld_resolve_ifunc(defobj, def); else target = (Elf_Addr)(defobj->relocbase + def->st_value); dbg("\"%s\" in \"%s\" ==> %p in \"%s\"", defobj->strtab + def->st_name, basename(obj->path), (void *)target, basename(defobj->path)); /* * If we have a function call tracing hook, and the * hook would like to keep tracing this one function, * prevent the relocation so we will wind up here * the next time again. * * We don't want to functrace calls from the functracer * to avoid recursive loops. */ if (rtld_functrace != NULL && obj != rtld_functrace_obj) { if (rtld_functrace(obj->path, defobj->path, defobj->strtab + def->st_name, stack)) { lock_release(rtld_bind_lock, &lockstate); return target; } } /* * Write the new contents for the jmpslot. Note that depending on * architecture, the value which we need to return back to the * lazy binding trampoline may or may not be the target * address. The value returned from reloc_jmpslot() is the value * that the trampoline needs. */ target = reloc_jmpslot(where, target, defobj, obj, rel); lock_release(rtld_bind_lock, &lockstate); return target; } /* * Error reporting function. Use it like printf. If formats the message * into a buffer, and sets things up so that the next call to dlerror() * will return the message. */ void _rtld_error(const char *fmt, ...) { static char buf[512]; va_list ap; va_start(ap, fmt); rtld_vsnprintf(buf, sizeof buf, fmt, ap); error_message = buf; va_end(ap); } /* * Return a dynamically-allocated copy of the current error message, if any. */ static char * errmsg_save(void) { return error_message == NULL ? NULL : xstrdup(error_message); } /* * Restore the current error message from a copy which was previously saved * by errmsg_save(). The copy is freed. */ static void errmsg_restore(char *saved_msg) { if (saved_msg == NULL) error_message = NULL; else { _rtld_error("%s", saved_msg); free(saved_msg); } } const char * basename(const char *name) { const char *p = strrchr(name, '/'); return p != NULL ? p + 1 : name; } static struct utsname uts; static char * origin_subst_one(char *real, const char *kw, const char *subst, bool may_free) { char *p, *p1, *res, *resp; int subst_len, kw_len, subst_count, old_len, new_len; kw_len = strlen(kw); /* * First, count the number of the keyword occurrences, to * preallocate the final string. */ for (p = real, subst_count = 0;; p = p1 + kw_len, subst_count++) { p1 = strstr(p, kw); if (p1 == NULL) break; } /* * If the keyword is not found, just return. */ if (subst_count == 0) return (may_free ? real : xstrdup(real)); /* * There is indeed something to substitute. Calculate the * length of the resulting string, and allocate it. */ subst_len = strlen(subst); old_len = strlen(real); new_len = old_len + (subst_len - kw_len) * subst_count; res = xmalloc(new_len + 1); /* * Now, execute the substitution loop. */ for (p = real, resp = res, *resp = '\0';;) { p1 = strstr(p, kw); if (p1 != NULL) { /* Copy the prefix before keyword. */ memcpy(resp, p, p1 - p); resp += p1 - p; /* Keyword replacement. */ memcpy(resp, subst, subst_len); resp += subst_len; *resp = '\0'; p = p1 + kw_len; } else break; } /* Copy to the end of string and finish. */ strcat(resp, p); if (may_free) free(real); return (res); } static char * origin_subst(char *real, const char *origin_path) { char *res1, *res2, *res3, *res4; if (uts.sysname[0] == '\0') { if (uname(&uts) != 0) { _rtld_error("utsname failed: %d", errno); return (NULL); } } res1 = origin_subst_one(real, "$ORIGIN", origin_path, false); res2 = origin_subst_one(res1, "$OSNAME", uts.sysname, true); res3 = origin_subst_one(res2, "$OSREL", uts.release, true); res4 = origin_subst_one(res3, "$PLATFORM", uts.machine, true); return (res4); } static void die(void) { const char *msg = dlerror(); if (msg == NULL) msg = "Fatal error"; rtld_fdputstr(STDERR_FILENO, msg); rtld_fdputchar(STDERR_FILENO, '\n'); _exit(1); } /* * Process a shared object's DYNAMIC section, and save the important * information in its Obj_Entry structure. */ static void digest_dynamic1(Obj_Entry *obj, int early, const Elf_Dyn **dyn_rpath, const Elf_Dyn **dyn_soname, const Elf_Dyn **dyn_runpath) { const Elf_Dyn *dynp; Needed_Entry **needed_tail = &obj->needed; Needed_Entry **needed_filtees_tail = &obj->needed_filtees; Needed_Entry **needed_aux_filtees_tail = &obj->needed_aux_filtees; const Elf_Hashelt *hashtab; const Elf32_Word *hashval; Elf32_Word bkt, nmaskwords; int bloom_size32; bool nmw_power2; int plttype = DT_REL; *dyn_rpath = NULL; *dyn_soname = NULL; *dyn_runpath = NULL; obj->bind_now = false; for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) { switch (dynp->d_tag) { case DT_REL: obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr); break; case DT_RELSZ: obj->relsize = dynp->d_un.d_val; break; case DT_RELENT: assert(dynp->d_un.d_val == sizeof(Elf_Rel)); break; case DT_JMPREL: obj->pltrel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr); break; case DT_PLTRELSZ: obj->pltrelsize = dynp->d_un.d_val; break; case DT_RELA: obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr); break; case DT_RELASZ: obj->relasize = dynp->d_un.d_val; break; case DT_RELAENT: assert(dynp->d_un.d_val == sizeof(Elf_Rela)); break; case DT_PLTREL: plttype = dynp->d_un.d_val; assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA); break; case DT_SYMTAB: obj->symtab = (const Elf_Sym *) (obj->relocbase + dynp->d_un.d_ptr); break; case DT_SYMENT: assert(dynp->d_un.d_val == sizeof(Elf_Sym)); break; case DT_STRTAB: obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr); break; case DT_STRSZ: obj->strsize = dynp->d_un.d_val; break; case DT_VERNEED: obj->verneed = (const Elf_Verneed *) (obj->relocbase + dynp->d_un.d_val); break; case DT_VERNEEDNUM: obj->verneednum = dynp->d_un.d_val; break; case DT_VERDEF: obj->verdef = (const Elf_Verdef *) (obj->relocbase + dynp->d_un.d_val); break; case DT_VERDEFNUM: obj->verdefnum = dynp->d_un.d_val; break; case DT_VERSYM: obj->versyms = (const Elf_Versym *)(obj->relocbase + dynp->d_un.d_val); break; case DT_HASH: { hashtab = (const Elf_Hashelt *)(obj->relocbase + dynp->d_un.d_ptr); obj->nbuckets = hashtab[0]; obj->nchains = hashtab[1]; obj->buckets = hashtab + 2; obj->chains = obj->buckets + obj->nbuckets; obj->valid_hash_sysv = obj->nbuckets > 0 && obj->nchains > 0 && obj->buckets != NULL; } break; case DT_GNU_HASH: { hashtab = (const Elf_Hashelt *)(obj->relocbase + dynp->d_un.d_ptr); obj->nbuckets_gnu = hashtab[0]; obj->symndx_gnu = hashtab[1]; nmaskwords = hashtab[2]; bloom_size32 = (__ELF_WORD_SIZE / 32) * nmaskwords; /* Number of bitmask words is required to be power of 2 */ nmw_power2 = powerof2(nmaskwords); obj->maskwords_bm_gnu = nmaskwords - 1; obj->shift2_gnu = hashtab[3]; obj->bloom_gnu = (Elf_Addr *) (hashtab + 4); obj->buckets_gnu = hashtab + 4 + bloom_size32; obj->chain_zero_gnu = obj->buckets_gnu + obj->nbuckets_gnu - obj->symndx_gnu; obj->valid_hash_gnu = nmw_power2 && obj->nbuckets_gnu > 0 && obj->buckets_gnu != NULL; } break; case DT_NEEDED: if (!obj->rtld) { Needed_Entry *nep = NEW(Needed_Entry); nep->name = dynp->d_un.d_val; nep->obj = NULL; nep->next = NULL; *needed_tail = nep; needed_tail = &nep->next; } break; case DT_FILTER: if (!obj->rtld) { Needed_Entry *nep = NEW(Needed_Entry); nep->name = dynp->d_un.d_val; nep->obj = NULL; nep->next = NULL; *needed_filtees_tail = nep; needed_filtees_tail = &nep->next; } break; case DT_AUXILIARY: if (!obj->rtld) { Needed_Entry *nep = NEW(Needed_Entry); nep->name = dynp->d_un.d_val; nep->obj = NULL; nep->next = NULL; *needed_aux_filtees_tail = nep; needed_aux_filtees_tail = &nep->next; } break; case DT_PLTGOT: obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr); break; case DT_TEXTREL: obj->textrel = true; break; case DT_SYMBOLIC: obj->symbolic = true; break; case DT_RPATH: /* * We have to wait until later to process this, because we * might not have gotten the address of the string table yet. */ *dyn_rpath = dynp; break; case DT_SONAME: *dyn_soname = dynp; break; case DT_RUNPATH: *dyn_runpath = dynp; break; case DT_INIT: obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); break; case DT_PREINIT_ARRAY: obj->preinit_array = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr); break; case DT_PREINIT_ARRAYSZ: obj->preinit_array_num = dynp->d_un.d_val / sizeof(Elf_Addr); break; case DT_INIT_ARRAY: obj->init_array = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr); break; case DT_INIT_ARRAYSZ: obj->init_array_num = dynp->d_un.d_val / sizeof(Elf_Addr); break; case DT_FINI: obj->fini = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr); break; case DT_FINI_ARRAY: obj->fini_array = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr); break; case DT_FINI_ARRAYSZ: obj->fini_array_num = dynp->d_un.d_val / sizeof(Elf_Addr); break; case DT_DEBUG: /* XXX - not implemented yet */ if (!early) dbg("Filling in DT_DEBUG entry"); ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug; break; case DT_FLAGS: if ((dynp->d_un.d_val & DF_ORIGIN) && trust) obj->z_origin = true; if (dynp->d_un.d_val & DF_SYMBOLIC) obj->symbolic = true; if (dynp->d_un.d_val & DF_TEXTREL) obj->textrel = true; if (dynp->d_un.d_val & DF_BIND_NOW) obj->bind_now = true; if (dynp->d_un.d_val & DF_STATIC_TLS) obj->static_tls = true; break; case DT_FLAGS_1: if (dynp->d_un.d_val & DF_1_NOOPEN) obj->z_noopen = true; if ((dynp->d_un.d_val & DF_1_ORIGIN) && trust) obj->z_origin = true; /*if (dynp->d_un.d_val & DF_1_GLOBAL) XXX ;*/ if (dynp->d_un.d_val & DF_1_BIND_NOW) obj->bind_now = true; if (dynp->d_un.d_val & DF_1_NODELETE) obj->z_nodelete = true; if (dynp->d_un.d_val & DF_1_LOADFLTR) obj->z_loadfltr = true; if (dynp->d_un.d_val & DF_1_INTERPOSE) obj->z_interpose = true; if (dynp->d_un.d_val & DF_1_NODEFLIB) obj->z_nodeflib = true; break; default: if (!early) { dbg("Ignoring d_tag %ld = %#lx", (long)dynp->d_tag, (long)dynp->d_tag); } break; } } obj->traced = false; if (plttype == DT_RELA) { obj->pltrela = (const Elf_Rela *) obj->pltrel; obj->pltrel = NULL; obj->pltrelasize = obj->pltrelsize; obj->pltrelsize = 0; } /* Determine size of dynsym table (equal to nchains of sysv hash) */ if (obj->valid_hash_sysv) obj->dynsymcount = obj->nchains; else if (obj->valid_hash_gnu) { obj->dynsymcount = 0; for (bkt = 0; bkt < obj->nbuckets_gnu; bkt++) { if (obj->buckets_gnu[bkt] == 0) continue; hashval = &obj->chain_zero_gnu[obj->buckets_gnu[bkt]]; do obj->dynsymcount++; while ((*hashval++ & 1u) == 0); } obj->dynsymcount += obj->symndx_gnu; } } static void digest_dynamic2(Obj_Entry *obj, const Elf_Dyn *dyn_rpath, const Elf_Dyn *dyn_soname, const Elf_Dyn *dyn_runpath) { if (obj->z_origin && obj->origin_path == NULL) { obj->origin_path = xmalloc(PATH_MAX); if (rtld_dirname_abs(obj->path, obj->origin_path) == -1) die(); } if (dyn_runpath != NULL) { obj->runpath = (char *)obj->strtab + dyn_runpath->d_un.d_val; if (obj->z_origin) obj->runpath = origin_subst(obj->runpath, obj->origin_path); } else if (dyn_rpath != NULL) { obj->rpath = (char *)obj->strtab + dyn_rpath->d_un.d_val; if (obj->z_origin) obj->rpath = origin_subst(obj->rpath, obj->origin_path); } if (dyn_soname != NULL) object_add_name(obj, obj->strtab + dyn_soname->d_un.d_val); } static void digest_dynamic(Obj_Entry *obj, int early) { const Elf_Dyn *dyn_rpath; const Elf_Dyn *dyn_soname; const Elf_Dyn *dyn_runpath; digest_dynamic1(obj, early, &dyn_rpath, &dyn_soname, &dyn_runpath); digest_dynamic2(obj, dyn_rpath, dyn_soname, dyn_runpath); } /* * Process a shared object's program header. This is used only for the * main program, when the kernel has already loaded the main program * into memory before calling the dynamic linker. It creates and * returns an Obj_Entry structure. */ static Obj_Entry * digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path) { Obj_Entry *obj; const Elf_Phdr *phlimit = phdr + phnum; const Elf_Phdr *ph; Elf_Addr note_start, note_end; int nsegs = 0; obj = obj_new(); for (ph = phdr; ph < phlimit; ph++) { if (ph->p_type != PT_PHDR) continue; obj->phdr = phdr; obj->phsize = ph->p_memsz; obj->relocbase = (caddr_t)phdr - ph->p_vaddr; break; } obj->stack_flags = PF_X | PF_R | PF_W; for (ph = phdr; ph < phlimit; ph++) { switch (ph->p_type) { case PT_INTERP: obj->interp = (const char *)(ph->p_vaddr + obj->relocbase); break; case PT_LOAD: if (nsegs == 0) { /* First load segment */ obj->vaddrbase = trunc_page(ph->p_vaddr); obj->mapbase = obj->vaddrbase + obj->relocbase; obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) - obj->vaddrbase; } else { /* Last load segment */ obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) - obj->vaddrbase; } nsegs++; break; case PT_DYNAMIC: obj->dynamic = (const Elf_Dyn *)(ph->p_vaddr + obj->relocbase); break; case PT_TLS: obj->tlsindex = 1; obj->tlssize = ph->p_memsz; obj->tlsalign = ph->p_align; obj->tlsinitsize = ph->p_filesz; obj->tlsinit = (void*)(ph->p_vaddr + obj->relocbase); break; case PT_GNU_STACK: obj->stack_flags = ph->p_flags; break; case PT_GNU_RELRO: obj->relro_page = obj->relocbase + trunc_page(ph->p_vaddr); obj->relro_size = round_page(ph->p_memsz); break; case PT_NOTE: obj->note_present = true; note_start = (Elf_Addr)obj->relocbase + ph->p_vaddr; note_end = note_start + ph->p_filesz; digest_notes(obj, note_start, note_end); break; } } if (nsegs < 1) { _rtld_error("%s: too few PT_LOAD segments", path); return NULL; } obj->entry = entry; return obj; } void digest_notes(Obj_Entry *obj, Elf_Addr note_start, Elf_Addr note_end) { const Elf_Note *note; const char *note_name; uintptr_t p; for (note = (const Elf_Note *)note_start; (Elf_Addr)note < note_end; note = (const Elf_Note *)((const char *)(note + 1) + roundup2(note->n_namesz, sizeof(Elf32_Addr)) + roundup2(note->n_descsz, sizeof(Elf32_Addr)))) { if (note->n_namesz != sizeof(NOTE_VENDOR) || note->n_descsz != sizeof(int32_t)) continue; if (note->n_type != ABI_NOTETYPE && note->n_type != CRT_NOINIT_NOTETYPE) continue; note_name = (const char *)(note + 1); if (strncmp(NOTE_VENDOR, note_name, sizeof(NOTE_VENDOR)) != 0) continue; switch (note->n_type) { case ABI_NOTETYPE: /* DragonFly osrel note */ p = (uintptr_t)(note + 1); p += roundup2(note->n_namesz, sizeof(Elf32_Addr)); obj->osrel = *(const int32_t *)(p); dbg("note osrel %d", obj->osrel); break; case CRT_NOINIT_NOTETYPE: /* DragonFly 'crt does not call init' note */ obj->crt_no_init = true; dbg("note crt_no_init"); break; } } } static Obj_Entry * dlcheck(void *handle) { Obj_Entry *obj; for (obj = obj_list; obj != NULL; obj = obj->next) if (obj == (Obj_Entry *) handle) break; if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) { _rtld_error("Invalid shared object handle %p", handle); return NULL; } return obj; } /* * If the given object is already in the donelist, return true. Otherwise * add the object to the list and return false. */ static bool donelist_check(DoneList *dlp, const Obj_Entry *obj) { unsigned int i; for (i = 0; i < dlp->num_used; i++) if (dlp->objs[i] == obj) return true; /* * Our donelist allocation should always be sufficient. But if * our threads locking isn't working properly, more shared objects * could have been loaded since we allocated the list. That should * never happen, but we'll handle it properly just in case it does. */ if (dlp->num_used < dlp->num_alloc) dlp->objs[dlp->num_used++] = obj; return false; } /* * Hash function for symbol table lookup. Don't even think about changing * this. It is specified by the System V ABI. */ unsigned long elf_hash(const char *name) { const unsigned char *p = (const unsigned char *) name; unsigned long h = 0; unsigned long g; while (*p != '\0') { h = (h << 4) + *p++; if ((g = h & 0xf0000000) != 0) h ^= g >> 24; h &= ~g; } return h; } /* * The GNU hash function is the Daniel J. Bernstein hash clipped to 32 bits * unsigned in case it's implemented with a wider type. */ static uint_fast32_t gnu_hash(const char *s) { uint_fast32_t h; unsigned char c; h = 5381; for (c = *s; c != '\0'; c = *++s) h = h * 33 + c; return (h & 0xffffffff); } /* * Find the library with the given name, and return its full pathname. * The returned string is dynamically allocated. Generates an error * message and returns NULL if the library cannot be found. * * If the second argument is non-NULL, then it refers to an already- * loaded shared object, whose library search path will be searched. * * If a library is successfully located via LD_LIBRARY_PATH_FDS, its * descriptor (which is close-on-exec) will be passed out via the third * argument. * * The search order is: * DT_RPATH in the referencing file _unless_ DT_RUNPATH is present (1) * DT_RPATH of the main object if DSO without defined DT_RUNPATH (1) * LD_LIBRARY_PATH * DT_RUNPATH in the referencing file * ldconfig hints (if -z nodefaultlib, filter out default library directories * from list) * /lib:/usr/lib _unless_ the referencing file is linked with -z nodefaultlib * * (1) Handled in digest_dynamic2 - rpath left NULL if runpath defined. */ static char * find_library(const char *xname, const Obj_Entry *refobj, int *fdp) { char *pathname; char *name; bool nodeflib, objgiven; objgiven = refobj != NULL; if (strchr(xname, '/') != NULL) { /* Hard coded pathname */ if (xname[0] != '/' && !trust) { _rtld_error("Absolute pathname required for shared object \"%s\"", xname); return NULL; } if (objgiven && refobj->z_origin) { return (origin_subst(__DECONST(char *, xname), refobj->origin_path)); } else { return (xstrdup(xname)); } } if (libmap_disable || !objgiven || (name = lm_find(refobj->path, xname)) == NULL) name = (char *)xname; dbg(" Searching for \"%s\"", name); nodeflib = objgiven ? refobj->z_nodeflib : false; if ((objgiven && (pathname = search_library_path(name, refobj->rpath)) != NULL) || (objgiven && refobj->runpath == NULL && refobj != obj_main && (pathname = search_library_path(name, obj_main->rpath)) != NULL) || (pathname = search_library_path(name, ld_library_path)) != NULL || (objgiven && (pathname = search_library_path(name, refobj->runpath)) != NULL) || (pathname = search_library_pathfds(name, ld_library_dirs, fdp)) != NULL || (pathname = search_library_path(name, gethints(nodeflib))) != NULL || (objgiven && !nodeflib && (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL)) return (pathname); if (objgiven && refobj->path != NULL) { _rtld_error("Shared object \"%s\" not found, required by \"%s\"", name, basename(refobj->path)); } else { _rtld_error("Shared object \"%s\" not found", name); } return NULL; } /* * Given a symbol number in a referencing object, find the corresponding * definition of the symbol. Returns a pointer to the symbol, or NULL if * no definition was found. Returns a pointer to the Obj_Entry of the * defining object via the reference parameter DEFOBJ_OUT. */ const Elf_Sym * find_symdef(unsigned long symnum, const Obj_Entry *refobj, const Obj_Entry **defobj_out, int flags, SymCache *cache, RtldLockState *lockstate) { const Elf_Sym *ref; const Elf_Sym *def; const Obj_Entry *defobj; SymLook req; const char *name; int res; /* * If we have already found this symbol, get the information from * the cache. */ if (symnum >= refobj->dynsymcount) return NULL; /* Bad object */ if (cache != NULL && cache[symnum].sym != NULL) { *defobj_out = cache[symnum].obj; return cache[symnum].sym; } ref = refobj->symtab + symnum; name = refobj->strtab + ref->st_name; def = NULL; defobj = NULL; /* * We don't have to do a full scale lookup if the symbol is local. * We know it will bind to the instance in this load module; to * which we already have a pointer (ie ref). By not doing a lookup, * we not only improve performance, but it also avoids unresolvable * symbols when local symbols are not in the hash table. * * This might occur for TLS module relocations, which simply use * symbol 0. */ if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) { if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) { _rtld_error("%s: Bogus symbol table entry %lu", refobj->path, symnum); } symlook_init(&req, name); req.flags = flags; req.ventry = fetch_ventry(refobj, symnum); req.lockstate = lockstate; res = symlook_default(&req, refobj); if (res == 0) { def = req.sym_out; defobj = req.defobj_out; } } else { def = ref; defobj = refobj; } /* * If we found no definition and the reference is weak, treat the * symbol as having the value zero. */ if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) { def = &sym_zero; defobj = obj_main; } if (def != NULL) { *defobj_out = defobj; /* Record the information in the cache to avoid subsequent lookups. */ if (cache != NULL) { cache[symnum].sym = def; cache[symnum].obj = defobj; } } else { if (refobj != &obj_rtld) _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name); } return def; } /* * Return the search path from the ldconfig hints file, reading it if * necessary. If nostdlib is true, then the default search paths are * not added to result. * * Returns NULL if there are problems with the hints file, * or if the search path there is empty. */ static const char * gethints(bool nostdlib) { static char *hints, *filtered_path; struct elfhints_hdr hdr; struct fill_search_info_args sargs, hargs; struct dl_serinfo smeta, hmeta, *SLPinfo, *hintinfo; struct dl_serpath *SLPpath, *hintpath; char *p; unsigned int SLPndx, hintndx, fndx, fcount; int fd; size_t flen; bool skip; /* First call, read the hints file */ if (hints == NULL) { /* Keep from trying again in case the hints file is bad. */ hints = ""; if ((fd = open(ld_elf_hints_path, O_RDONLY | O_CLOEXEC)) == -1) return (NULL); if (read(fd, &hdr, sizeof hdr) != sizeof hdr || hdr.magic != ELFHINTS_MAGIC || hdr.version != 1) { close(fd); return (NULL); } p = xmalloc(hdr.dirlistlen + 1); if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 || read(fd, p, hdr.dirlistlen + 1) != (ssize_t)hdr.dirlistlen + 1) { free(p); close(fd); return (NULL); } hints = p; close(fd); } /* * If caller agreed to receive list which includes the default * paths, we are done. Otherwise, if we still have not * calculated filtered result, do it now. */ if (!nostdlib) return (hints[0] != '\0' ? hints : NULL); if (filtered_path != NULL) goto filt_ret; /* * Obtain the list of all configured search paths, and the * list of the default paths. * * First estimate the size of the results. */ smeta.dls_size = __offsetof(struct dl_serinfo, dls_serpath); smeta.dls_cnt = 0; hmeta.dls_size = __offsetof(struct dl_serinfo, dls_serpath); hmeta.dls_cnt = 0; sargs.request = RTLD_DI_SERINFOSIZE; sargs.serinfo = &smeta; hargs.request = RTLD_DI_SERINFOSIZE; hargs.serinfo = &hmeta; path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &sargs); path_enumerate(p, fill_search_info, &hargs); SLPinfo = xmalloc(smeta.dls_size); hintinfo = xmalloc(hmeta.dls_size); /* * Next fetch both sets of paths. */ sargs.request = RTLD_DI_SERINFO; sargs.serinfo = SLPinfo; sargs.serpath = &SLPinfo->dls_serpath[0]; sargs.strspace = (char *)&SLPinfo->dls_serpath[smeta.dls_cnt]; hargs.request = RTLD_DI_SERINFO; hargs.serinfo = hintinfo; hargs.serpath = &hintinfo->dls_serpath[0]; hargs.strspace = (char *)&hintinfo->dls_serpath[hmeta.dls_cnt]; path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &sargs); path_enumerate(p, fill_search_info, &hargs); /* * Now calculate the difference between two sets, by excluding * standard paths from the full set. */ fndx = 0; fcount = 0; filtered_path = xmalloc(hdr.dirlistlen + 1); hintpath = &hintinfo->dls_serpath[0]; for (hintndx = 0; hintndx < hmeta.dls_cnt; hintndx++, hintpath++) { skip = false; SLPpath = &SLPinfo->dls_serpath[0]; /* * Check each standard path against current. */ for (SLPndx = 0; SLPndx < smeta.dls_cnt; SLPndx++, SLPpath++) { /* matched, skip the path */ if (!strcmp(hintpath->dls_name, SLPpath->dls_name)) { skip = true; break; } } if (skip) continue; /* * Not matched against any standard path, add the path * to result. Separate consecutive paths with ':'. */ if (fcount > 0) { filtered_path[fndx] = ':'; fndx++; } fcount++; flen = strlen(hintpath->dls_name); strncpy((filtered_path + fndx), hintpath->dls_name, flen); fndx += flen; } filtered_path[fndx] = '\0'; free(SLPinfo); free(hintinfo); filt_ret: return (filtered_path[0] != '\0' ? filtered_path : NULL); } static void init_dag(Obj_Entry *root) { const Needed_Entry *needed; const Objlist_Entry *elm; DoneList donelist; if (root->dag_inited) return; donelist_init(&donelist); /* Root object belongs to own DAG. */ objlist_push_tail(&root->dldags, root); objlist_push_tail(&root->dagmembers, root); donelist_check(&donelist, root); /* * Add dependencies of root object to DAG in breadth order * by exploiting the fact that each new object get added * to the tail of the dagmembers list. */ STAILQ_FOREACH(elm, &root->dagmembers, link) { for (needed = elm->obj->needed; needed != NULL; needed = needed->next) { if (needed->obj == NULL || donelist_check(&donelist, needed->obj)) continue; objlist_push_tail(&needed->obj->dldags, root); objlist_push_tail(&root->dagmembers, needed->obj); } } root->dag_inited = true; } static void process_nodelete(Obj_Entry *root) { const Objlist_Entry *elm; /* * Walk over object DAG and process every dependent object that * is marked as DF_1_NODELETE. They need to grow their own DAG, * which then should have its reference upped separately. */ STAILQ_FOREACH(elm, &root->dagmembers, link) { if (elm->obj != NULL && elm->obj->z_nodelete && !elm->obj->ref_nodel) { dbg("obj %s nodelete", elm->obj->path); init_dag(elm->obj); ref_dag(elm->obj); elm->obj->ref_nodel = true; } } } /* * Initialize the dynamic linker. The argument is the address at which * the dynamic linker has been mapped into memory. The primary task of * this function is to relocate the dynamic linker. */ static void init_rtld(caddr_t mapbase, Elf_Auxinfo **aux_info) { Obj_Entry objtmp; /* Temporary rtld object */ const Elf_Ehdr *ehdr; const Elf_Dyn *dyn_rpath; const Elf_Dyn *dyn_soname; const Elf_Dyn *dyn_runpath; /* * Conjure up an Obj_Entry structure for the dynamic linker. * * The "path" member can't be initialized yet because string constants * cannot yet be accessed. Below we will set it correctly. */ memset(&objtmp, 0, sizeof(objtmp)); objtmp.path = NULL; objtmp.rtld = true; objtmp.mapbase = mapbase; #ifdef PIC objtmp.relocbase = mapbase; #endif if (RTLD_IS_DYNAMIC()) { objtmp.dynamic = rtld_dynamic(&objtmp); digest_dynamic1(&objtmp, 1, &dyn_rpath, &dyn_soname, &dyn_runpath); assert(objtmp.needed == NULL); assert(!objtmp.textrel); /* * Temporarily put the dynamic linker entry into the object list, so * that symbols can be found. */ relocate_objects(&objtmp, true, &objtmp, 0, NULL); } ehdr = (Elf_Ehdr *)mapbase; objtmp.phdr = (Elf_Phdr *)((char *)mapbase + ehdr->e_phoff); objtmp.phsize = ehdr->e_phnum * sizeof(objtmp.phdr[0]); /* Initialize the object list. */ obj_tail = &obj_list; /* Now that non-local variables can be accesses, copy out obj_rtld. */ memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld)); #ifdef ENABLE_OSRELDATE if (aux_info[AT_OSRELDATE] != NULL) osreldate = aux_info[AT_OSRELDATE]->a_un.a_val; #endif digest_dynamic2(&obj_rtld, dyn_rpath, dyn_soname, dyn_runpath); /* Replace the path with a dynamically allocated copy. */ obj_rtld.path = xstrdup(PATH_RTLD); r_debug.r_brk = r_debug_state; r_debug.r_state = RT_CONSISTENT; } /* * Add the init functions from a needed object list (and its recursive * needed objects) to "list". This is not used directly; it is a helper * function for initlist_add_objects(). The write lock must be held * when this function is called. */ static void initlist_add_neededs(Needed_Entry *needed, Objlist *list) { /* Recursively process the successor needed objects. */ if (needed->next != NULL) initlist_add_neededs(needed->next, list); /* Process the current needed object. */ if (needed->obj != NULL) initlist_add_objects(needed->obj, &needed->obj->next, list); } /* * Scan all of the DAGs rooted in the range of objects from "obj" to * "tail" and add their init functions to "list". This recurses over * the DAGs and ensure the proper init ordering such that each object's * needed libraries are initialized before the object itself. At the * same time, this function adds the objects to the global finalization * list "list_fini" in the opposite order. The write lock must be * held when this function is called. */ static void initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list) { if (obj->init_scanned || obj->init_done) return; obj->init_scanned = true; /* Recursively process the successor objects. */ if (&obj->next != tail) initlist_add_objects(obj->next, tail, list); /* Recursively process the needed objects. */ if (obj->needed != NULL) initlist_add_neededs(obj->needed, list); if (obj->needed_filtees != NULL) initlist_add_neededs(obj->needed_filtees, list); if (obj->needed_aux_filtees != NULL) initlist_add_neededs(obj->needed_aux_filtees, list); /* Add the object to the init list. */ if (obj->preinit_array != (Elf_Addr)NULL || obj->init != (Elf_Addr)NULL || obj->init_array != (Elf_Addr)NULL) objlist_push_tail(list, obj); /* Add the object to the global fini list in the reverse order. */ if ((obj->fini != (Elf_Addr)NULL || obj->fini_array != (Elf_Addr)NULL) && !obj->on_fini_list) { objlist_push_head(&list_fini, obj); obj->on_fini_list = true; } } #ifndef FPTR_TARGET #define FPTR_TARGET(f) ((Elf_Addr) (f)) #endif static void free_needed_filtees(Needed_Entry *n) { Needed_Entry *needed, *needed1; for (needed = n; needed != NULL; needed = needed->next) { if (needed->obj != NULL) { dlclose(needed->obj); needed->obj = NULL; } } for (needed = n; needed != NULL; needed = needed1) { needed1 = needed->next; free(needed); } } static void unload_filtees(Obj_Entry *obj) { free_needed_filtees(obj->needed_filtees); obj->needed_filtees = NULL; free_needed_filtees(obj->needed_aux_filtees); obj->needed_aux_filtees = NULL; obj->filtees_loaded = false; } static void load_filtee1(Obj_Entry *obj, Needed_Entry *needed, int flags, RtldLockState *lockstate) { for (; needed != NULL; needed = needed->next) { needed->obj = dlopen_object(obj->strtab + needed->name, -1, obj, flags, ((ld_loadfltr || obj->z_loadfltr) ? RTLD_NOW : RTLD_LAZY) | RTLD_LOCAL, lockstate); } } static void load_filtees(Obj_Entry *obj, int flags, RtldLockState *lockstate) { lock_restart_for_upgrade(lockstate); if (!obj->filtees_loaded) { load_filtee1(obj, obj->needed_filtees, flags, lockstate); load_filtee1(obj, obj->needed_aux_filtees, flags, lockstate); obj->filtees_loaded = true; } } static int process_needed(Obj_Entry *obj, Needed_Entry *needed, int flags) { Obj_Entry *obj1; for (; needed != NULL; needed = needed->next) { obj1 = needed->obj = load_object(obj->strtab + needed->name, -1, obj, flags & ~RTLD_LO_NOLOAD); if (obj1 == NULL && !ld_tracing && (flags & RTLD_LO_FILTEES) == 0) return (-1); } return (0); } /* * Given a shared object, traverse its list of needed objects, and load * each of them. Returns 0 on success. Generates an error message and * returns -1 on failure. */ static int load_needed_objects(Obj_Entry *first, int flags) { Obj_Entry *obj; for (obj = first; obj != NULL; obj = obj->next) { if (process_needed(obj, obj->needed, flags) == -1) return (-1); } return (0); } static int load_preload_objects(void) { char *p = ld_preload; Obj_Entry *obj; static const char delim[] = " \t:;"; if (p == NULL) return 0; p += strspn(p, delim); while (*p != '\0') { size_t len = strcspn(p, delim); char savech; SymLook req; int res; savech = p[len]; p[len] = '\0'; obj = load_object(p, -1, NULL, 0); if (obj == NULL) return -1; /* XXX - cleanup */ obj->z_interpose = true; p[len] = savech; p += len; p += strspn(p, delim); /* Check for the magic tracing function */ symlook_init(&req, RTLD_FUNCTRACE); res = symlook_obj(&req, obj); if (res == 0) { rtld_functrace = (void *)(req.defobj_out->relocbase + req.sym_out->st_value); rtld_functrace_obj = req.defobj_out; } } LD_UTRACE(UTRACE_PRELOAD_FINISHED, NULL, NULL, 0, 0, NULL); return 0; } static const char * printable_path(const char *path) { return (path == NULL ? "" : path); } /* * Load a shared object into memory, if it is not already loaded. The * object may be specified by name or by user-supplied file descriptor * fd_u. In the later case, the fd_u descriptor is not closed, but its * duplicate is. * * Returns a pointer to the Obj_Entry for the object. Returns NULL * on failure. */ static Obj_Entry * load_object(const char *name, int fd_u, const Obj_Entry *refobj, int flags) { Obj_Entry *obj; int fd; struct stat sb; char *path; fd = -1; if (name != NULL) { for (obj = obj_list->next; obj != NULL; obj = obj->next) { if (object_match_name(obj, name)) return (obj); } path = find_library(name, refobj, &fd); if (path == NULL) return (NULL); } else path = NULL; if (fd >= 0) { /* * search_library_pathfds() opens a fresh file descriptor for the * library, so there is no need to dup(). */ } else if (fd_u == -1) { /* * If we didn't find a match by pathname, or the name is not * supplied, open the file and check again by device and inode. * This avoids false mismatches caused by multiple links or ".." * in pathnames. * * To avoid a race, we open the file and use fstat() rather than * using stat(). */ if ((fd = open(path, O_RDONLY | O_CLOEXEC)) == -1) { _rtld_error("Cannot open \"%s\"", path); free(path); return (NULL); } } else { fd = fcntl(fd_u, F_DUPFD_CLOEXEC, 0); if (fd == -1) { _rtld_error("Cannot dup fd"); free(path); return (NULL); } } if (fstat(fd, &sb) == -1) { _rtld_error("Cannot fstat \"%s\"", printable_path(path)); close(fd); free(path); return NULL; } for (obj = obj_list->next; obj != NULL; obj = obj->next) if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) break; if (obj != NULL && name != NULL) { object_add_name(obj, name); free(path); close(fd); return obj; } if (flags & RTLD_LO_NOLOAD) { free(path); close(fd); return (NULL); } /* First use of this object, so we must map it in */ obj = do_load_object(fd, name, path, &sb, flags); if (obj == NULL) free(path); close(fd); return obj; } static Obj_Entry * do_load_object(int fd, const char *name, char *path, struct stat *sbp, int flags) { Obj_Entry *obj; struct statfs fs; /* * but first, make sure that environment variables haven't been * used to circumvent the noexec flag on a filesystem. */ if (dangerous_ld_env) { if (fstatfs(fd, &fs) != 0) { _rtld_error("Cannot fstatfs \"%s\"", printable_path(path)); return NULL; } if (fs.f_flags & MNT_NOEXEC) { _rtld_error("Cannot execute objects on %s\n", fs.f_mntonname); return NULL; } } dbg("loading \"%s\"", printable_path(path)); obj = map_object(fd, printable_path(path), sbp); if (obj == NULL) return NULL; /* * If DT_SONAME is present in the object, digest_dynamic2 already * added it to the object names. */ if (name != NULL) object_add_name(obj, name); obj->path = path; digest_dynamic(obj, 0); dbg("%s valid_hash_sysv %d valid_hash_gnu %d dynsymcount %d", obj->path, obj->valid_hash_sysv, obj->valid_hash_gnu, obj->dynsymcount); if (obj->z_noopen && (flags & (RTLD_LO_DLOPEN | RTLD_LO_TRACE)) == RTLD_LO_DLOPEN) { dbg("refusing to load non-loadable \"%s\"", obj->path); _rtld_error("Cannot dlopen non-loadable %s", obj->path); munmap(obj->mapbase, obj->mapsize); obj_free(obj); return (NULL); } *obj_tail = obj; obj_tail = &obj->next; obj_count++; obj_loads++; linkmap_add(obj); /* for GDB & dlinfo() */ #if 0 max_stack_flags |= obj->stack_flags; #endif dbg(" %p .. %p: %s", obj->mapbase, obj->mapbase + obj->mapsize - 1, obj->path); if (obj->textrel) dbg(" WARNING: %s has impure text", obj->path); LD_UTRACE(UTRACE_LOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0, obj->path); return obj; } static Obj_Entry * obj_from_addr(const void *addr) { Obj_Entry *obj; for (obj = obj_list; obj != NULL; obj = obj->next) { if (addr < (void *) obj->mapbase) continue; if (addr < (void *) (obj->mapbase + obj->mapsize)) return obj; } return NULL; } /* * If the main program is defined with a .preinit_array section, call * each function in order. This must occur before the initialization * of any shared object or the main program. */ static void preinit_main(void) { Elf_Addr *preinit_addr; int index; preinit_addr = (Elf_Addr *)obj_main->preinit_array; if (preinit_addr == NULL) return; for (index = 0; index < obj_main->preinit_array_num; index++) { if (preinit_addr[index] != 0 && preinit_addr[index] != 1) { dbg("calling preinit function for %s at %p", obj_main->path, (void *)preinit_addr[index]); LD_UTRACE(UTRACE_INIT_CALL, obj_main, (void *)preinit_addr[index], 0, 0, obj_main->path); call_init_pointer(obj_main, preinit_addr[index]); } } } /* * Call the finalization functions for each of the objects in "list" * belonging to the DAG of "root" and referenced once. If NULL "root" * is specified, every finalization function will be called regardless * of the reference count and the list elements won't be freed. All of * the objects are expected to have non-NULL fini functions. */ static void objlist_call_fini(Objlist *list, Obj_Entry *root, RtldLockState *lockstate) { Objlist_Entry *elm; char *saved_msg; Elf_Addr *fini_addr; int index; assert(root == NULL || root->refcount == 1); /* * Preserve the current error message since a fini function might * call into the dynamic linker and overwrite it. */ saved_msg = errmsg_save(); do { STAILQ_FOREACH(elm, list, link) { if (root != NULL && (elm->obj->refcount != 1 || objlist_find(&root->dagmembers, elm->obj) == NULL)) continue; /* Remove object from fini list to prevent recursive invocation. */ STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link); /* * XXX: If a dlopen() call references an object while the * fini function is in progress, we might end up trying to * unload the referenced object in dlclose() or the object * won't be unloaded although its fini function has been * called. */ lock_release(rtld_bind_lock, lockstate); /* * It is legal to have both DT_FINI and DT_FINI_ARRAY defined. * When this happens, DT_FINI_ARRAY is processed first. * It is also processed backwards. It is possible to encounter * DT_FINI_ARRAY elements with values of 0 or 1, but they need * to be ignored. */ fini_addr = (Elf_Addr *)elm->obj->fini_array; if (fini_addr != NULL && elm->obj->fini_array_num > 0) { for (index = elm->obj->fini_array_num - 1; index >= 0; index--) { if (fini_addr[index] != 0 && fini_addr[index] != 1) { dbg("calling fini array function for %s at %p", elm->obj->path, (void *)fini_addr[index]); LD_UTRACE(UTRACE_FINI_CALL, elm->obj, (void *)fini_addr[index], 0, 0, elm->obj->path); call_initfini_pointer(elm->obj, fini_addr[index]); } } } if (elm->obj->fini != (Elf_Addr)NULL) { dbg("calling fini function for %s at %p", elm->obj->path, (void *)elm->obj->fini); LD_UTRACE(UTRACE_FINI_CALL, elm->obj, (void *)elm->obj->fini, 0, 0, elm->obj->path); call_initfini_pointer(elm->obj, elm->obj->fini); } wlock_acquire(rtld_bind_lock, lockstate); /* No need to free anything if process is going down. */ if (root != NULL) free(elm); /* * We must restart the list traversal after every fini call * because a dlclose() call from the fini function or from * another thread might have modified the reference counts. */ break; } } while (elm != NULL); errmsg_restore(saved_msg); } /* * Call the initialization functions for each of the objects in * "list". All of the objects are expected to have non-NULL init * functions. */ static void objlist_call_init(Objlist *list, RtldLockState *lockstate) { Objlist_Entry *elm; Obj_Entry *obj; char *saved_msg; Elf_Addr *init_addr; int index; /* * Clean init_scanned flag so that objects can be rechecked and * possibly initialized earlier if any of vectors called below * cause the change by using dlopen. */ for (obj = obj_list; obj != NULL; obj = obj->next) obj->init_scanned = false; /* * Preserve the current error message since an init function might * call into the dynamic linker and overwrite it. */ saved_msg = errmsg_save(); STAILQ_FOREACH(elm, list, link) { if (elm->obj->init_done) /* Initialized early. */ continue; /* * Race: other thread might try to use this object before current * one completes the initilization. Not much can be done here * without better locking. */ elm->obj->init_done = true; lock_release(rtld_bind_lock, lockstate); /* * It is legal to have both DT_INIT and DT_INIT_ARRAY defined. * When this happens, DT_INIT is processed first. * It is possible to encounter DT_INIT_ARRAY elements with values * of 0 or 1, but they need to be ignored. */ if (elm->obj->init != (Elf_Addr)NULL) { dbg("calling init function for %s at %p", elm->obj->path, (void *)elm->obj->init); LD_UTRACE(UTRACE_INIT_CALL, elm->obj, (void *)elm->obj->init, 0, 0, elm->obj->path); call_initfini_pointer(elm->obj, elm->obj->init); } init_addr = (Elf_Addr *)elm->obj->init_array; if (init_addr != NULL) { for (index = 0; index < elm->obj->init_array_num; index++) { if (init_addr[index] != 0 && init_addr[index] != 1) { dbg("calling init array function for %s at %p", elm->obj->path, (void *)init_addr[index]); LD_UTRACE(UTRACE_INIT_CALL, elm->obj, (void *)init_addr[index], 0, 0, elm->obj->path); call_init_pointer(elm->obj, init_addr[index]); } } } wlock_acquire(rtld_bind_lock, lockstate); } errmsg_restore(saved_msg); } static void objlist_clear(Objlist *list) { Objlist_Entry *elm; while (!STAILQ_EMPTY(list)) { elm = STAILQ_FIRST(list); STAILQ_REMOVE_HEAD(list, link); free(elm); } } static Objlist_Entry * objlist_find(Objlist *list, const Obj_Entry *obj) { Objlist_Entry *elm; STAILQ_FOREACH(elm, list, link) if (elm->obj == obj) return elm; return NULL; } static void objlist_init(Objlist *list) { STAILQ_INIT(list); } static void objlist_push_head(Objlist *list, Obj_Entry *obj) { Objlist_Entry *elm; elm = NEW(Objlist_Entry); elm->obj = obj; STAILQ_INSERT_HEAD(list, elm, link); } static void objlist_push_tail(Objlist *list, Obj_Entry *obj) { Objlist_Entry *elm; elm = NEW(Objlist_Entry); elm->obj = obj; STAILQ_INSERT_TAIL(list, elm, link); } static void objlist_put_after(Objlist *list, Obj_Entry *listobj, Obj_Entry *obj) { Objlist_Entry *elm, *listelm; STAILQ_FOREACH(listelm, list, link) { if (listelm->obj == listobj) break; } elm = NEW(Objlist_Entry); elm->obj = obj; if (listelm != NULL) STAILQ_INSERT_AFTER(list, listelm, elm, link); else STAILQ_INSERT_TAIL(list, elm, link); } static void objlist_remove(Objlist *list, Obj_Entry *obj) { Objlist_Entry *elm; if ((elm = objlist_find(list, obj)) != NULL) { STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link); free(elm); } } /* * Relocate dag rooted in the specified object. * Returns 0 on success, or -1 on failure. */ static int relocate_object_dag(Obj_Entry *root, bool bind_now, Obj_Entry *rtldobj, int flags, RtldLockState *lockstate) { Objlist_Entry *elm; int error; error = 0; STAILQ_FOREACH(elm, &root->dagmembers, link) { error = relocate_object(elm->obj, bind_now, rtldobj, flags, lockstate); if (error == -1) break; } return (error); } /* * Prepare for, or clean after, relocating an object marked with * DT_TEXTREL or DF_TEXTREL. Before relocating, all read-only * segments are remapped read-write. After relocations are done, the * segment's permissions are returned back to the modes specified in * the phdrs. If any relocation happened, or always for wired * program, COW is triggered. */ static int reloc_textrel_prot(Obj_Entry *obj, bool before) { const Elf_Phdr *ph; void *base; size_t l, sz; int prot; for (l = obj->phsize / sizeof(*ph), ph = obj->phdr; l > 0; l--, ph++) { if (ph->p_type != PT_LOAD || (ph->p_flags & PF_W) != 0) continue; base = obj->relocbase + trunc_page(ph->p_vaddr); sz = round_page(ph->p_vaddr + ph->p_filesz) - trunc_page(ph->p_vaddr); prot = convert_prot(ph->p_flags) | (before ? PROT_WRITE : 0); /* * Make sure modified text segments are included in the * core dump since we modified it. This unfortunately causes the * entire text segment to core-out but we don't have much of a * choice. We could try to only reenable core dumps on pages * in which relocations occured but that is likely most of the text * pages anyway, and even that would not work because the rest of * the text pages would wind up as a read-only OBJT_DEFAULT object * (created due to our modifications) backed by the original OBJT_VNODE * object, and the ELF coredump code is currently only able to dump * vnode records for pure vnode-backed mappings, not vnode backings * to memory objects. */ if (before == false) madvise(base, sz, MADV_CORE); if (mprotect(base, sz, prot) == -1) { _rtld_error("%s: Cannot write-%sable text segment: %s", obj->path, before ? "en" : "dis", rtld_strerror(errno)); return (-1); } } return (0); } /* * Relocate single object. * Returns 0 on success, or -1 on failure. */ static int relocate_object(Obj_Entry *obj, bool bind_now, Obj_Entry *rtldobj, int flags, RtldLockState *lockstate) { if (obj->relocated) return (0); obj->relocated = true; if (obj != rtldobj) dbg("relocating \"%s\"", obj->path); if (obj->symtab == NULL || obj->strtab == NULL || !(obj->valid_hash_sysv || obj->valid_hash_gnu)) { _rtld_error("%s: Shared object has no run-time symbol table", obj->path); return (-1); } /* There are relocations to the write-protected text segment. */ if (obj->textrel && reloc_textrel_prot(obj, true) != 0) return (-1); /* Process the non-PLT non-IFUNC relocations. */ if (reloc_non_plt(obj, rtldobj, flags, lockstate)) return (-1); /* Re-protected the text segment. */ if (obj->textrel && reloc_textrel_prot(obj, false) != 0) return (-1); /* Set the special PLT or GOT entries. */ init_pltgot(obj); /* Process the PLT relocations. */ if (reloc_plt(obj) == -1) return (-1); /* Relocate the jump slots if we are doing immediate binding. */ if (obj->bind_now || bind_now) if (reloc_jmpslots(obj, flags, lockstate) == -1) return (-1); /* * Process the non-PLT IFUNC relocations. The relocations are * processed in two phases, because IFUNC resolvers may * reference other symbols, which must be readily processed * before resolvers are called. */ if (obj->non_plt_gnu_ifunc && reloc_non_plt(obj, rtldobj, flags | SYMLOOK_IFUNC, lockstate)) return (-1); /* * Set up the magic number and version in the Obj_Entry. These * were checked in the crt1.o from the original ElfKit, so we * set them for backward compatibility. */ obj->magic = RTLD_MAGIC; obj->version = RTLD_VERSION; /* * Set relocated data to read-only status if protection specified */ if (obj->relro_size) { if (mprotect(obj->relro_page, obj->relro_size, PROT_READ) == -1) { _rtld_error("%s: Cannot enforce relro relocation: %s", obj->path, rtld_strerror(errno)); return (-1); } obj->relro_protected = true; } return (0); } /* * Relocate newly-loaded shared objects. The argument is a pointer to * the Obj_Entry for the first such object. All objects from the first * to the end of the list of objects are relocated. Returns 0 on success, * or -1 on failure. */ static int relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj, int flags, RtldLockState *lockstate) { Obj_Entry *obj; int error; for (error = 0, obj = first; obj != NULL; obj = obj->next) { error = relocate_object(obj, bind_now, rtldobj, flags, lockstate); if (error == -1) break; } return (error); } /* * The handling of R_MACHINE_IRELATIVE relocations and jumpslots * referencing STT_GNU_IFUNC symbols is postponed till the other * relocations are done. The indirect functions specified as * ifunc are allowed to call other symbols, so we need to have * objects relocated before asking for resolution from indirects. * * The R_MACHINE_IRELATIVE slots are resolved in greedy fashion, * instead of the usual lazy handling of PLT slots. It is * consistent with how GNU does it. */ static int resolve_object_ifunc(Obj_Entry *obj, bool bind_now, int flags, RtldLockState *lockstate) { if (obj->irelative && reloc_iresolve(obj, lockstate) == -1) return (-1); if (obj->irelative_nonplt && reloc_iresolve_nonplt(obj, lockstate) == -1) return (-1); if ((obj->bind_now || bind_now) && obj->gnu_ifunc && reloc_gnu_ifunc(obj, flags, lockstate) == -1) return (-1); return (0); } static int resolve_objects_ifunc(Obj_Entry *first, bool bind_now, int flags, RtldLockState *lockstate) { Obj_Entry *obj; for (obj = first; obj != NULL; obj = obj->next) { if (resolve_object_ifunc(obj, bind_now, flags, lockstate) == -1) return (-1); } return (0); } static int initlist_objects_ifunc(Objlist *list, bool bind_now, int flags, RtldLockState *lockstate) { Objlist_Entry *elm; STAILQ_FOREACH(elm, list, link) { if (resolve_object_ifunc(elm->obj, bind_now, flags, lockstate) == -1) return (-1); } return (0); } /* * Cleanup procedure. It will be called (by the atexit mechanism) just * before the process exits. */ static void rtld_exit(void) { RtldLockState lockstate; wlock_acquire(rtld_bind_lock, &lockstate); dbg("rtld_exit()"); objlist_call_fini(&list_fini, NULL, &lockstate); /* No need to remove the items from the list, since we are exiting. */ if (!libmap_disable) lm_fini(); lock_release(rtld_bind_lock, &lockstate); } /* * Iterate over a search path, translate each element, and invoke the * callback on the result. */ static void * path_enumerate(const char *path, path_enum_proc callback, void *arg) { const char *trans; if (path == NULL) return (NULL); path += strspn(path, ":;"); while (*path != '\0') { size_t len; char *res; len = strcspn(path, ":;"); trans = lm_findn(NULL, path, len); if (trans) res = callback(trans, strlen(trans), arg); else res = callback(path, len, arg); if (res != NULL) return (res); path += len; path += strspn(path, ":;"); } return (NULL); } struct try_library_args { const char *name; size_t namelen; char *buffer; size_t buflen; }; static void * try_library_path(const char *dir, size_t dirlen, void *param) { struct try_library_args *arg; arg = param; if (*dir == '/' || trust) { char *pathname; if (dirlen + 1 + arg->namelen + 1 > arg->buflen) return (NULL); pathname = arg->buffer; strncpy(pathname, dir, dirlen); pathname[dirlen] = '/'; strcpy(pathname + dirlen + 1, arg->name); dbg(" Trying \"%s\"", pathname); if (access(pathname, F_OK) == 0) { /* We found it */ pathname = xmalloc(dirlen + 1 + arg->namelen + 1); strcpy(pathname, arg->buffer); return (pathname); } } return (NULL); } static char * search_library_path(const char *name, const char *path) { char *p; struct try_library_args arg; if (path == NULL) return NULL; arg.name = name; arg.namelen = strlen(name); arg.buffer = xmalloc(PATH_MAX); arg.buflen = PATH_MAX; p = path_enumerate(path, try_library_path, &arg); free(arg.buffer); return (p); } /* * Finds the library with the given name using the directory descriptors * listed in the LD_LIBRARY_PATH_FDS environment variable. * * Returns a freshly-opened close-on-exec file descriptor for the library, * or -1 if the library cannot be found. */ static char * search_library_pathfds(const char *name, const char *path, int *fdp) { char *envcopy, *fdstr, *found, *last_token; size_t len; int dirfd, fd; dbg("%s('%s', '%s', fdp)", __func__, name, path); /* Don't load from user-specified libdirs into setuid binaries. */ if (!trust) return (NULL); /* We can't do anything if LD_LIBRARY_PATH_FDS isn't set. */ if (path == NULL) return (NULL); /* LD_LIBRARY_PATH_FDS only works with relative paths. */ if (name[0] == '/') { dbg("Absolute path (%s) passed to %s", name, __func__); return (NULL); } /* * Use strtok_r() to walk the FD:FD:FD list. This requires a local * copy of the path, as strtok_r rewrites separator tokens * with '\0'. * * NOTE: strtok() uses a __thread static and cannot be used by rtld. */ found = NULL; envcopy = xstrdup(path); for (fdstr = strtok_r(envcopy, ":", &last_token); fdstr != NULL; fdstr = strtok_r(NULL, ":", &last_token)) { dirfd = parse_libdir(fdstr); if (dirfd < 0) break; fd = openat(dirfd, name, O_RDONLY | O_CLOEXEC); if (fd >= 0) { *fdp = fd; len = strlen(fdstr) + strlen(name) + 3; found = xmalloc(len); if (rtld_snprintf(found, len, "#%d/%s", dirfd, name) < 0) { _rtld_error("error generating '%d/%s'", dirfd, name); die(); } dbg("open('%s') => %d", found, fd); break; } } free(envcopy); return (found); } int dlclose(void *handle) { Obj_Entry *root; RtldLockState lockstate; wlock_acquire(rtld_bind_lock, &lockstate); root = dlcheck(handle); if (root == NULL) { lock_release(rtld_bind_lock, &lockstate); return -1; } LD_UTRACE(UTRACE_DLCLOSE_START, handle, NULL, 0, root->dl_refcount, root->path); /* Unreference the object and its dependencies. */ root->dl_refcount--; if (root->refcount == 1) { /* * The object will be no longer referenced, so we must unload it. * First, call the fini functions. */ objlist_call_fini(&list_fini, root, &lockstate); unref_dag(root); /* Finish cleaning up the newly-unreferenced objects. */ GDB_STATE(RT_DELETE,&root->linkmap); unload_object(root); GDB_STATE(RT_CONSISTENT,NULL); } else unref_dag(root); LD_UTRACE(UTRACE_DLCLOSE_STOP, handle, NULL, 0, 0, NULL); lock_release(rtld_bind_lock, &lockstate); return 0; } char * dlerror(void) { char *msg = error_message; error_message = NULL; return msg; } void * dlopen(const char *name, int mode) { return (rtld_dlopen(name, -1, mode)); } void * fdlopen(int fd, int mode) { return (rtld_dlopen(NULL, fd, mode)); } static void * rtld_dlopen(const char *name, int fd, int mode) { RtldLockState lockstate; int lo_flags; LD_UTRACE(UTRACE_DLOPEN_START, NULL, NULL, 0, mode, name); ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1"; if (ld_tracing != NULL) { rlock_acquire(rtld_bind_lock, &lockstate); if (sigsetjmp(lockstate.env, 0) != 0) lock_upgrade(rtld_bind_lock, &lockstate); environ = (char **)*get_program_var_addr("environ", &lockstate); lock_release(rtld_bind_lock, &lockstate); } lo_flags = RTLD_LO_DLOPEN; if (mode & RTLD_NODELETE) lo_flags |= RTLD_LO_NODELETE; if (mode & RTLD_NOLOAD) lo_flags |= RTLD_LO_NOLOAD; if (ld_tracing != NULL) lo_flags |= RTLD_LO_TRACE; return (dlopen_object(name, fd, obj_main, lo_flags, mode & (RTLD_MODEMASK | RTLD_GLOBAL), NULL)); } static void dlopen_cleanup(Obj_Entry *obj) { obj->dl_refcount--; unref_dag(obj); if (obj->refcount == 0) unload_object(obj); } static Obj_Entry * dlopen_object(const char *name, int fd, Obj_Entry *refobj, int lo_flags, int mode, RtldLockState *lockstate) { Obj_Entry **old_obj_tail; Obj_Entry *obj; Objlist initlist; RtldLockState mlockstate; int result; objlist_init(&initlist); if (lockstate == NULL && !(lo_flags & RTLD_LO_EARLY)) { wlock_acquire(rtld_bind_lock, &mlockstate); lockstate = &mlockstate; } GDB_STATE(RT_ADD,NULL); old_obj_tail = obj_tail; obj = NULL; if (name == NULL && fd == -1) { obj = obj_main; obj->refcount++; } else { obj = load_object(name, fd, refobj, lo_flags); } if (obj) { obj->dl_refcount++; if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL) objlist_push_tail(&list_global, obj); if (*old_obj_tail != NULL) { /* We loaded something new. */ assert(*old_obj_tail == obj); if ((lo_flags & RTLD_LO_EARLY) == 0 && obj->static_tls && !allocate_tls_offset(obj)) { _rtld_error("%s: No space available " "for static TLS", obj->path); result = -1; } else { result = 0; } if (result == 0) { result = load_needed_objects( obj, lo_flags & (RTLD_LO_DLOPEN | RTLD_LO_EARLY)); } init_dag(obj); ref_dag(obj); if (result != -1) result = rtld_verify_versions(&obj->dagmembers); if (result != -1 && ld_tracing) goto trace; if (result == -1 || relocate_object_dag(obj, (mode & RTLD_MODEMASK) == RTLD_NOW, &obj_rtld, (lo_flags & RTLD_LO_EARLY) ? SYMLOOK_EARLY : 0, lockstate) == -1) { dlopen_cleanup(obj); obj = NULL; } else if (lo_flags & RTLD_LO_EARLY) { /* * Do not call the init functions for early loaded * filtees. The image is still not initialized enough * for them to work. * * Our object is found by the global object list and * will be ordered among all init calls done right * before transferring control to main. */ } else { /* Make list of init functions to call. */ initlist_add_objects(obj, &obj->next, &initlist); } /* * Process all no_delete objects here, given them own * DAGs to prevent their dependencies from being unloaded. * This has to be done after we have loaded all of the * dependencies, so that we do not miss any. */ if (obj != NULL) process_nodelete(obj); } else { /* * Bump the reference counts for objects on this DAG. If * this is the first dlopen() call for the object that was * already loaded as a dependency, initialize the dag * starting at it. */ init_dag(obj); ref_dag(obj); if ((lo_flags & RTLD_LO_TRACE) != 0) goto trace; } if (obj != NULL && ((lo_flags & RTLD_LO_NODELETE) != 0 || obj->z_nodelete) && !obj->ref_nodel) { dbg("obj %s nodelete", obj->path); ref_dag(obj); obj->z_nodelete = obj->ref_nodel = true; } } LD_UTRACE(UTRACE_DLOPEN_STOP, obj, NULL, 0, obj ? obj->dl_refcount : 0, name); GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL); if ((lo_flags & RTLD_LO_EARLY) == 0) { map_stacks_exec(lockstate); if (obj) distribute_static_tls(&initlist, lockstate); } if (initlist_objects_ifunc(&initlist, (mode & RTLD_MODEMASK) == RTLD_NOW, (lo_flags & RTLD_LO_EARLY) ? SYMLOOK_EARLY : 0, lockstate) == -1) { objlist_clear(&initlist); dlopen_cleanup(obj); if (lockstate == &mlockstate) lock_release(rtld_bind_lock, lockstate); return (NULL); } if (!(lo_flags & RTLD_LO_EARLY)) { /* Call the init functions. */ objlist_call_init(&initlist, lockstate); } objlist_clear(&initlist); if (lockstate == &mlockstate) lock_release(rtld_bind_lock, lockstate); return obj; trace: trace_loaded_objects(obj); if (lockstate == &mlockstate) lock_release(rtld_bind_lock, lockstate); exit(0); } static void * do_dlsym(void *handle, const char *name, void *retaddr, const Ver_Entry *ve, int flags) { DoneList donelist; const Obj_Entry *obj, *defobj; const Elf_Sym *def; SymLook req; RtldLockState lockstate; tls_index ti; int res; def = NULL; defobj = NULL; symlook_init(&req, name); req.ventry = ve; req.flags = flags | SYMLOOK_IN_PLT; req.lockstate = &lockstate; rlock_acquire(rtld_bind_lock, &lockstate); if (sigsetjmp(lockstate.env, 0) != 0) lock_upgrade(rtld_bind_lock, &lockstate); if (handle == NULL || handle == RTLD_NEXT || handle == RTLD_DEFAULT || handle == RTLD_SELF || handle == RTLD_ALL) { if (handle != RTLD_ALL) { if ((obj = obj_from_addr(retaddr)) == NULL) { _rtld_error("Cannot determine caller's shared object"); lock_release(rtld_bind_lock, &lockstate); return NULL; } } else { obj = obj_list; } if (handle == NULL) { /* Just the caller's shared object. */ res = symlook_obj(&req, obj); if (res == 0) { def = req.sym_out; defobj = req.defobj_out; } } else if (handle == RTLD_NEXT || /* Objects after caller's */ handle == RTLD_SELF || /* ... caller included */ handle == RTLD_ALL) { /* All Objects */ if (handle == RTLD_NEXT) obj = obj->next; for (; obj != NULL; obj = obj->next) { res = symlook_obj(&req, obj); if (res == 0) { if (def == NULL || ELF_ST_BIND(req.sym_out->st_info) != STB_WEAK) { def = req.sym_out; defobj = req.defobj_out; if (ELF_ST_BIND(def->st_info) != STB_WEAK) break; } } } /* * Search the dynamic linker itself, and possibly resolve the * symbol from there. This is how the application links to * dynamic linker services such as dlopen. */ if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { res = symlook_obj(&req, &obj_rtld); if (res == 0) { def = req.sym_out; defobj = req.defobj_out; } } } else { assert(handle == RTLD_DEFAULT); res = symlook_default(&req, obj); if (res == 0) { defobj = req.defobj_out; def = req.sym_out; } } } else { if ((obj = dlcheck(handle)) == NULL) { lock_release(rtld_bind_lock, &lockstate); return NULL; } donelist_init(&donelist); if (obj->mainprog) { /* Handle obtained by dlopen(NULL, ...) implies global scope. */ res = symlook_global(&req, &donelist); if (res == 0) { def = req.sym_out; defobj = req.defobj_out; } /* * Search the dynamic linker itself, and possibly resolve the * symbol from there. This is how the application links to * dynamic linker services such as dlopen. */ if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { res = symlook_obj(&req, &obj_rtld); if (res == 0) { def = req.sym_out; defobj = req.defobj_out; } } } else { /* Search the whole DAG rooted at the given object. */ res = symlook_list(&req, &obj->dagmembers, &donelist); if (res == 0) { def = req.sym_out; defobj = req.defobj_out; } } } if (def != NULL) { lock_release(rtld_bind_lock, &lockstate); /* * The value required by the caller is derived from the value * of the symbol. this is simply the relocated value of the * symbol. */ if (ELF_ST_TYPE(def->st_info) == STT_FUNC) return (make_function_pointer(def, defobj)); else if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) return (rtld_resolve_ifunc(defobj, def)); else if (ELF_ST_TYPE(def->st_info) == STT_TLS) { ti.ti_module = defobj->tlsindex; ti.ti_offset = def->st_value; return (__tls_get_addr(&ti)); } else return (defobj->relocbase + def->st_value); } _rtld_error("Undefined symbol \"%s\"", name); lock_release(rtld_bind_lock, &lockstate); return NULL; } void * dlsym(void *handle, const char *name) { return do_dlsym(handle, name, __builtin_return_address(0), NULL, SYMLOOK_DLSYM); } dlfunc_t dlfunc(void *handle, const char *name) { union { void *d; dlfunc_t f; } rv; rv.d = do_dlsym(handle, name, __builtin_return_address(0), NULL, SYMLOOK_DLSYM); return (rv.f); } void * dlvsym(void *handle, const char *name, const char *version) { Ver_Entry ventry; ventry.name = version; ventry.file = NULL; ventry.hash = elf_hash(version); ventry.flags= 0; return do_dlsym(handle, name, __builtin_return_address(0), &ventry, SYMLOOK_DLSYM); } int _rtld_addr_phdr(const void *addr, struct dl_phdr_info *phdr_info) { const Obj_Entry *obj; RtldLockState lockstate; rlock_acquire(rtld_bind_lock, &lockstate); obj = obj_from_addr(addr); if (obj == NULL) { _rtld_error("No shared object contains address"); lock_release(rtld_bind_lock, &lockstate); return (0); } rtld_fill_dl_phdr_info(obj, phdr_info); lock_release(rtld_bind_lock, &lockstate); return (1); } int dladdr(const void *addr, Dl_info *info) { const Obj_Entry *obj; const Elf_Sym *def; void *symbol_addr; unsigned long symoffset; RtldLockState lockstate; rlock_acquire(rtld_bind_lock, &lockstate); obj = obj_from_addr(addr); if (obj == NULL) { _rtld_error("No shared object contains address"); lock_release(rtld_bind_lock, &lockstate); return 0; } info->dli_fname = obj->path; info->dli_fbase = obj->mapbase; info->dli_saddr = NULL; info->dli_sname = NULL; /* * Walk the symbol list looking for the symbol whose address is * closest to the address sent in. */ for (symoffset = 0; symoffset < obj->dynsymcount; symoffset++) { def = obj->symtab + symoffset; /* * For skip the symbol if st_shndx is either SHN_UNDEF or * SHN_COMMON. */ if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON) continue; /* * If the symbol is greater than the specified address, or if it * is further away from addr than the current nearest symbol, * then reject it. */ symbol_addr = obj->relocbase + def->st_value; if (symbol_addr > addr || symbol_addr < info->dli_saddr) continue; /* Update our idea of the nearest symbol. */ info->dli_sname = obj->strtab + def->st_name; info->dli_saddr = symbol_addr; /* Exact match? */ if (info->dli_saddr == addr) break; } lock_release(rtld_bind_lock, &lockstate); return 1; } int dlinfo(void *handle, int request, void *p) { const Obj_Entry *obj; RtldLockState lockstate; int error; rlock_acquire(rtld_bind_lock, &lockstate); if (handle == NULL || handle == RTLD_SELF) { void *retaddr; retaddr = __builtin_return_address(0); /* __GNUC__ only */ if ((obj = obj_from_addr(retaddr)) == NULL) _rtld_error("Cannot determine caller's shared object"); } else obj = dlcheck(handle); if (obj == NULL) { lock_release(rtld_bind_lock, &lockstate); return (-1); } error = 0; switch (request) { case RTLD_DI_LINKMAP: *((struct link_map const **)p) = &obj->linkmap; break; case RTLD_DI_ORIGIN: error = rtld_dirname(obj->path, p); break; case RTLD_DI_SERINFOSIZE: case RTLD_DI_SERINFO: error = do_search_info(obj, request, (struct dl_serinfo *)p); break; default: _rtld_error("Invalid request %d passed to dlinfo()", request); error = -1; } lock_release(rtld_bind_lock, &lockstate); return (error); } static void rtld_fill_dl_phdr_info(const Obj_Entry *obj, struct dl_phdr_info *phdr_info) { phdr_info->dlpi_addr = (Elf_Addr)obj->relocbase; phdr_info->dlpi_name = obj->path; phdr_info->dlpi_phdr = obj->phdr; phdr_info->dlpi_phnum = obj->phsize / sizeof(obj->phdr[0]); phdr_info->dlpi_tls_modid = obj->tlsindex; phdr_info->dlpi_tls_data = obj->tlsinit; phdr_info->dlpi_adds = obj_loads; phdr_info->dlpi_subs = obj_loads - obj_count; } int dl_iterate_phdr(__dl_iterate_hdr_callback callback, void *param) { struct dl_phdr_info phdr_info; const Obj_Entry *obj; RtldLockState bind_lockstate, phdr_lockstate; int error; wlock_acquire(rtld_phdr_lock, &phdr_lockstate); rlock_acquire(rtld_bind_lock, &bind_lockstate); error = 0; for (obj = obj_list; obj != NULL; obj = obj->next) { rtld_fill_dl_phdr_info(obj, &phdr_info); if ((error = callback(&phdr_info, sizeof phdr_info, param)) != 0) break; } if (error == 0) { rtld_fill_dl_phdr_info(&obj_rtld, &phdr_info); error = callback(&phdr_info, sizeof(phdr_info), param); } lock_release(rtld_bind_lock, &bind_lockstate); lock_release(rtld_phdr_lock, &phdr_lockstate); return (error); } static void * fill_search_info(const char *dir, size_t dirlen, void *param) { struct fill_search_info_args *arg; arg = param; if (arg->request == RTLD_DI_SERINFOSIZE) { arg->serinfo->dls_cnt ++; arg->serinfo->dls_size += sizeof(struct dl_serpath) + dirlen + 1; } else { struct dl_serpath *s_entry; s_entry = arg->serpath; s_entry->dls_name = arg->strspace; s_entry->dls_flags = arg->flags; strncpy(arg->strspace, dir, dirlen); arg->strspace[dirlen] = '\0'; arg->strspace += dirlen + 1; arg->serpath++; } return (NULL); } static int do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info) { struct dl_serinfo _info; struct fill_search_info_args args; args.request = RTLD_DI_SERINFOSIZE; args.serinfo = &_info; _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath); _info.dls_cnt = 0; path_enumerate(obj->rpath, fill_search_info, &args); path_enumerate(ld_library_path, fill_search_info, &args); path_enumerate(obj->runpath, fill_search_info, &args); path_enumerate(gethints(obj->z_nodeflib), fill_search_info, &args); if (!obj->z_nodeflib) path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args); if (request == RTLD_DI_SERINFOSIZE) { info->dls_size = _info.dls_size; info->dls_cnt = _info.dls_cnt; return (0); } if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) { _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()"); return (-1); } args.request = RTLD_DI_SERINFO; args.serinfo = info; args.serpath = &info->dls_serpath[0]; args.strspace = (char *)&info->dls_serpath[_info.dls_cnt]; args.flags = LA_SER_RUNPATH; if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL) return (-1); args.flags = LA_SER_LIBPATH; if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL) return (-1); args.flags = LA_SER_RUNPATH; if (path_enumerate(obj->runpath, fill_search_info, &args) != NULL) return (-1); args.flags = LA_SER_CONFIG; if (path_enumerate(gethints(obj->z_nodeflib), fill_search_info, &args) != NULL) return (-1); args.flags = LA_SER_DEFAULT; if (!obj->z_nodeflib && path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL) return (-1); return (0); } static int rtld_dirname(const char *path, char *bname) { const char *endp; /* Empty or NULL string gets treated as "." */ if (path == NULL || *path == '\0') { bname[0] = '.'; bname[1] = '\0'; return (0); } /* Strip trailing slashes */ endp = path + strlen(path) - 1; while (endp > path && *endp == '/') endp--; /* Find the start of the dir */ while (endp > path && *endp != '/') endp--; /* Either the dir is "/" or there are no slashes */ if (endp == path) { bname[0] = *endp == '/' ? '/' : '.'; bname[1] = '\0'; return (0); } else { do { endp--; } while (endp > path && *endp == '/'); } if (endp - path + 2 > PATH_MAX) { _rtld_error("Filename is too long: %s", path); return(-1); } strncpy(bname, path, endp - path + 1); bname[endp - path + 1] = '\0'; return (0); } static int rtld_dirname_abs(const char *path, char *base) { char base_rel[PATH_MAX]; if (rtld_dirname(path, base) == -1) return (-1); if (base[0] == '/') return (0); if (getcwd(base_rel, sizeof(base_rel)) == NULL || strlcat(base_rel, "/", sizeof(base_rel)) >= sizeof(base_rel) || strlcat(base_rel, base, sizeof(base_rel)) >= sizeof(base_rel)) return (-1); strcpy(base, base_rel); return (0); } static void linkmap_add(Obj_Entry *obj) { struct link_map *l = &obj->linkmap; struct link_map *prev; obj->linkmap.l_name = obj->path; obj->linkmap.l_addr = obj->mapbase; obj->linkmap.l_ld = obj->dynamic; if (r_debug.r_map == NULL) { r_debug.r_map = l; return; } /* * Scan to the end of the list, but not past the entry for the * dynamic linker, which we want to keep at the very end. */ for (prev = r_debug.r_map; prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap; prev = prev->l_next) ; /* Link in the new entry. */ l->l_prev = prev; l->l_next = prev->l_next; if (l->l_next != NULL) l->l_next->l_prev = l; prev->l_next = l; } static void linkmap_delete(Obj_Entry *obj) { struct link_map *l = &obj->linkmap; if (l->l_prev == NULL) { if ((r_debug.r_map = l->l_next) != NULL) l->l_next->l_prev = NULL; return; } if ((l->l_prev->l_next = l->l_next) != NULL) l->l_next->l_prev = l->l_prev; } /* * Function for the debugger to set a breakpoint on to gain control. * * The two parameters allow the debugger to easily find and determine * what the runtime loader is doing and to whom it is doing it. * * When the loadhook trap is hit (r_debug_state, set at program * initialization), the arguments can be found on the stack: * * +8 struct link_map *m * +4 struct r_debug *rd * +0 RetAddr */ void r_debug_state(struct r_debug* rd, struct link_map *m) { /* * The following is a hack to force the compiler to emit calls to * this function, even when optimizing. If the function is empty, * the compiler is not obliged to emit any code for calls to it, * even when marked __noinline. However, gdb depends on those * calls being made. */ __asm __volatile("" : : : "memory"); } /* * A function called after init routines have completed. This can be used to * break before a program's entry routine is called, and can be used when * main is not available in the symbol table. */ void _r_debug_postinit(struct link_map *m) { /* See r_debug_state(). */ __asm __volatile("" : : : "memory"); } /* * Get address of the pointer variable in the main program. * Prefer non-weak symbol over the weak one. */ static const void ** get_program_var_addr(const char *name, RtldLockState *lockstate) { SymLook req; DoneList donelist; symlook_init(&req, name); req.lockstate = lockstate; donelist_init(&donelist); if (symlook_global(&req, &donelist) != 0) return (NULL); if (ELF_ST_TYPE(req.sym_out->st_info) == STT_FUNC) return ((const void **)make_function_pointer(req.sym_out, req.defobj_out)); else if (ELF_ST_TYPE(req.sym_out->st_info) == STT_GNU_IFUNC) return ((const void **)rtld_resolve_ifunc(req.defobj_out, req.sym_out)); else return ((const void **)(req.defobj_out->relocbase + req.sym_out->st_value)); } /* * Set a pointer variable in the main program to the given value. This * is used to set key variables such as "environ" before any of the * init functions are called. */ static void set_program_var(const char *name, const void *value) { const void **addr; if ((addr = get_program_var_addr(name, NULL)) != NULL) { dbg("\"%s\": *%p <-- %p", name, addr, value); *addr = value; } } /* * Search the global objects, including dependencies and main object, * for the given symbol. */ static int symlook_global(SymLook *req, DoneList *donelist) { SymLook req1; const Objlist_Entry *elm; int res; symlook_init_from_req(&req1, req); /* Search all objects loaded at program start up. */ if (req->defobj_out == NULL || ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) { res = symlook_list(&req1, &list_main, donelist); if (res == 0 && (req->defobj_out == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) { req->sym_out = req1.sym_out; req->defobj_out = req1.defobj_out; assert(req->defobj_out != NULL); } } /* Search all DAGs whose roots are RTLD_GLOBAL objects. */ STAILQ_FOREACH(elm, &list_global, link) { if (req->defobj_out != NULL && ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK) break; res = symlook_list(&req1, &elm->obj->dagmembers, donelist); if (res == 0 && (req->defobj_out == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) { req->sym_out = req1.sym_out; req->defobj_out = req1.defobj_out; assert(req->defobj_out != NULL); } } return (req->sym_out != NULL ? 0 : ESRCH); } /* * This is a special version of getenv which is far more efficient * at finding LD_ environment vars. */ static const char * _getenv_ld(const char *id) { const char *envp; int i, j; int idlen = strlen(id); if (ld_index == LD_ARY_CACHE) return(getenv(id)); if (ld_index == 0) { for (i = j = 0; (envp = environ[i]) != NULL && j < LD_ARY_CACHE; ++i) { if (envp[0] == 'L' && envp[1] == 'D' && envp[2] == '_') ld_ary[j++] = envp; } if (j == 0) ld_ary[j++] = ""; ld_index = j; } for (i = ld_index - 1; i >= 0; --i) { if (strncmp(ld_ary[i], id, idlen) == 0 && ld_ary[i][idlen] == '=') return(ld_ary[i] + idlen + 1); } return(NULL); } /* * Given a symbol name in a referencing object, find the corresponding * definition of the symbol. Returns a pointer to the symbol, or NULL if * no definition was found. Returns a pointer to the Obj_Entry of the * defining object via the reference parameter DEFOBJ_OUT. */ static int symlook_default(SymLook *req, const Obj_Entry *refobj) { DoneList donelist; const Objlist_Entry *elm; SymLook req1; int res; donelist_init(&donelist); symlook_init_from_req(&req1, req); /* Look first in the referencing object if linked symbolically. */ if (refobj->symbolic && !donelist_check(&donelist, refobj)) { res = symlook_obj(&req1, refobj); if (res == 0) { req->sym_out = req1.sym_out; req->defobj_out = req1.defobj_out; assert(req->defobj_out != NULL); } } symlook_global(req, &donelist); /* Search all dlopened DAGs containing the referencing object. */ STAILQ_FOREACH(elm, &refobj->dldags, link) { if (req->sym_out != NULL && ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK) break; res = symlook_list(&req1, &elm->obj->dagmembers, &donelist); if (res == 0 && (req->sym_out == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) { req->sym_out = req1.sym_out; req->defobj_out = req1.defobj_out; assert(req->defobj_out != NULL); } } /* * Search the dynamic linker itself, and possibly resolve the * symbol from there. This is how the application links to * dynamic linker services such as dlopen. */ if (req->sym_out == NULL || ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) { res = symlook_obj(&req1, &obj_rtld); if (res == 0) { req->sym_out = req1.sym_out; req->defobj_out = req1.defobj_out; assert(req->defobj_out != NULL); } } return (req->sym_out != NULL ? 0 : ESRCH); } static int symlook_list(SymLook *req, const Objlist *objlist, DoneList *dlp) { const Elf_Sym *def; const Obj_Entry *defobj; const Objlist_Entry *elm; SymLook req1; int res; def = NULL; defobj = NULL; STAILQ_FOREACH(elm, objlist, link) { if (donelist_check(dlp, elm->obj)) continue; symlook_init_from_req(&req1, req); if ((res = symlook_obj(&req1, elm->obj)) == 0) { if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) { def = req1.sym_out; defobj = req1.defobj_out; if (ELF_ST_BIND(def->st_info) != STB_WEAK) break; } } } if (def != NULL) { req->sym_out = def; req->defobj_out = defobj; return (0); } return (ESRCH); } /* * Search the chain of DAGS cointed to by the given Needed_Entry * for a symbol of the given name. Each DAG is scanned completely * before advancing to the next one. Returns a pointer to the symbol, * or NULL if no definition was found. */ static int symlook_needed(SymLook *req, const Needed_Entry *needed, DoneList *dlp) { const Elf_Sym *def; const Needed_Entry *n; const Obj_Entry *defobj; SymLook req1; int res; def = NULL; defobj = NULL; symlook_init_from_req(&req1, req); for (n = needed; n != NULL; n = n->next) { if (n->obj == NULL || (res = symlook_list(&req1, &n->obj->dagmembers, dlp)) != 0) continue; if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) { def = req1.sym_out; defobj = req1.defobj_out; if (ELF_ST_BIND(def->st_info) != STB_WEAK) break; } } if (def != NULL) { req->sym_out = def; req->defobj_out = defobj; return (0); } return (ESRCH); } /* * Search the symbol table of a single shared object for a symbol of * the given name and version, if requested. Returns a pointer to the * symbol, or NULL if no definition was found. If the object is * filter, return filtered symbol from filtee. * * The symbol's hash value is passed in for efficiency reasons; that * eliminates many recomputations of the hash value. */ int symlook_obj(SymLook *req, const Obj_Entry *obj) { DoneList donelist; SymLook req1; int flags, res, mres; /* * If there is at least one valid hash at this point, we prefer to * use the faster GNU version if available. */ if (obj->valid_hash_gnu) mres = symlook_obj1_gnu(req, obj); else if (obj->valid_hash_sysv) mres = symlook_obj1_sysv(req, obj); else return (EINVAL); if (mres == 0) { if (obj->needed_filtees != NULL) { flags = (req->flags & SYMLOOK_EARLY) ? RTLD_LO_EARLY : 0; load_filtees(__DECONST(Obj_Entry *, obj), flags, req->lockstate); donelist_init(&donelist); symlook_init_from_req(&req1, req); res = symlook_needed(&req1, obj->needed_filtees, &donelist); if (res == 0) { req->sym_out = req1.sym_out; req->defobj_out = req1.defobj_out; } return (res); } if (obj->needed_aux_filtees != NULL) { flags = (req->flags & SYMLOOK_EARLY) ? RTLD_LO_EARLY : 0; load_filtees(__DECONST(Obj_Entry *, obj), flags, req->lockstate); donelist_init(&donelist); symlook_init_from_req(&req1, req); res = symlook_needed(&req1, obj->needed_aux_filtees, &donelist); if (res == 0) { req->sym_out = req1.sym_out; req->defobj_out = req1.defobj_out; return (res); } } } return (mres); } /* Symbol match routine common to both hash functions */ static bool matched_symbol(SymLook *req, const Obj_Entry *obj, Sym_Match_Result *result, const unsigned long symnum) { Elf_Versym verndx; const Elf_Sym *symp; const char *strp; symp = obj->symtab + symnum; strp = obj->strtab + symp->st_name; switch (ELF_ST_TYPE(symp->st_info)) { case STT_FUNC: case STT_NOTYPE: case STT_OBJECT: case STT_COMMON: case STT_GNU_IFUNC: if (symp->st_value == 0) return (false); /* fallthrough */ case STT_TLS: if (symp->st_shndx != SHN_UNDEF) break; else if (((req->flags & SYMLOOK_IN_PLT) == 0) && (ELF_ST_TYPE(symp->st_info) == STT_FUNC)) break; /* fallthrough */ default: return (false); } if (strcmp(req->name, strp) != 0) return (false); if (req->ventry == NULL) { if (obj->versyms != NULL) { verndx = VER_NDX(obj->versyms[symnum]); if (verndx > obj->vernum) { _rtld_error( "%s: symbol %s references wrong version %d", obj->path, obj->strtab + symnum, verndx); return (false); } /* * If we are not called from dlsym (i.e. this * is a normal relocation from unversioned * binary), accept the symbol immediately if * it happens to have first version after this * shared object became versioned. Otherwise, * if symbol is versioned and not hidden, * remember it. If it is the only symbol with * this name exported by the shared object, it * will be returned as a match by the calling * function. If symbol is global (verndx < 2) * accept it unconditionally. */ if ((req->flags & SYMLOOK_DLSYM) == 0 && verndx == VER_NDX_GIVEN) { result->sym_out = symp; return (true); } else if (verndx >= VER_NDX_GIVEN) { if ((obj->versyms[symnum] & VER_NDX_HIDDEN) == 0) { if (result->vsymp == NULL) result->vsymp = symp; result->vcount++; } return (false); } } result->sym_out = symp; return (true); } if (obj->versyms == NULL) { if (object_match_name(obj, req->ventry->name)) { _rtld_error("%s: object %s should provide version %s " "for symbol %s", obj_rtld.path, obj->path, req->ventry->name, obj->strtab + symnum); return (false); } } else { verndx = VER_NDX(obj->versyms[symnum]); if (verndx > obj->vernum) { _rtld_error("%s: symbol %s references wrong version %d", obj->path, obj->strtab + symnum, verndx); return (false); } if (obj->vertab[verndx].hash != req->ventry->hash || strcmp(obj->vertab[verndx].name, req->ventry->name)) { /* * Version does not match. Look if this is a * global symbol and if it is not hidden. If * global symbol (verndx < 2) is available, * use it. Do not return symbol if we are * called by dlvsym, because dlvsym looks for * a specific version and default one is not * what dlvsym wants. */ if ((req->flags & SYMLOOK_DLSYM) || (verndx >= VER_NDX_GIVEN) || (obj->versyms[symnum] & VER_NDX_HIDDEN)) return (false); } } result->sym_out = symp; return (true); } /* * Search for symbol using SysV hash function. * obj->buckets is known not to be NULL at this point; the test for this was * performed with the obj->valid_hash_sysv assignment. */ static int symlook_obj1_sysv(SymLook *req, const Obj_Entry *obj) { unsigned long symnum; Sym_Match_Result matchres; matchres.sym_out = NULL; matchres.vsymp = NULL; matchres.vcount = 0; for (symnum = obj->buckets[req->hash % obj->nbuckets]; symnum != STN_UNDEF; symnum = obj->chains[symnum]) { if (symnum >= obj->nchains) return (ESRCH); /* Bad object */ if (matched_symbol(req, obj, &matchres, symnum)) { req->sym_out = matchres.sym_out; req->defobj_out = obj; return (0); } } if (matchres.vcount == 1) { req->sym_out = matchres.vsymp; req->defobj_out = obj; return (0); } return (ESRCH); } /* Search for symbol using GNU hash function */ static int symlook_obj1_gnu(SymLook *req, const Obj_Entry *obj) { Elf_Addr bloom_word; const Elf32_Word *hashval; Elf32_Word bucket; Sym_Match_Result matchres; unsigned int h1, h2; unsigned long symnum; matchres.sym_out = NULL; matchres.vsymp = NULL; matchres.vcount = 0; /* Pick right bitmask word from Bloom filter array */ bloom_word = obj->bloom_gnu[(req->hash_gnu / __ELF_WORD_SIZE) & obj->maskwords_bm_gnu]; /* Calculate modulus word size of gnu hash and its derivative */ h1 = req->hash_gnu & (__ELF_WORD_SIZE - 1); h2 = ((req->hash_gnu >> obj->shift2_gnu) & (__ELF_WORD_SIZE - 1)); /* Filter out the "definitely not in set" queries */ if (((bloom_word >> h1) & (bloom_word >> h2) & 1) == 0) return (ESRCH); /* Locate hash chain and corresponding value element*/ bucket = obj->buckets_gnu[req->hash_gnu % obj->nbuckets_gnu]; if (bucket == 0) return (ESRCH); hashval = &obj->chain_zero_gnu[bucket]; do { if (((*hashval ^ req->hash_gnu) >> 1) == 0) { symnum = hashval - obj->chain_zero_gnu; if (matched_symbol(req, obj, &matchres, symnum)) { req->sym_out = matchres.sym_out; req->defobj_out = obj; return (0); } } } while ((*hashval++ & 1) == 0); if (matchres.vcount == 1) { req->sym_out = matchres.vsymp; req->defobj_out = obj; return (0); } return (ESRCH); } static void trace_loaded_objects(Obj_Entry *obj) { const char *fmt1, *fmt2, *fmt, *main_local, *list_containers; int c; if ((main_local = _getenv_ld("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL) main_local = ""; if ((fmt1 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL) fmt1 = "\t%o => %p (%x)\n"; if ((fmt2 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL) fmt2 = "\t%o (%x)\n"; list_containers = _getenv_ld("LD_TRACE_LOADED_OBJECTS_ALL"); for (; obj; obj = obj->next) { Needed_Entry *needed; char *name, *path; bool is_lib; if (list_containers && obj->needed != NULL) rtld_printf("%s:\n", obj->path); for (needed = obj->needed; needed; needed = needed->next) { if (needed->obj != NULL) { if (needed->obj->traced && !list_containers) continue; needed->obj->traced = true; path = needed->obj->path; } else path = "not found"; name = (char *)obj->strtab + needed->name; is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */ fmt = is_lib ? fmt1 : fmt2; while ((c = *fmt++) != '\0') { switch (c) { default: rtld_putchar(c); continue; case '\\': switch (c = *fmt) { case '\0': continue; case 'n': rtld_putchar('\n'); break; case 't': rtld_putchar('\t'); break; } break; case '%': switch (c = *fmt) { case '\0': continue; case '%': default: rtld_putchar(c); break; case 'A': rtld_putstr(main_local); break; case 'a': rtld_putstr(obj_main->path); break; case 'o': rtld_putstr(name); break; case 'p': rtld_putstr(path); break; case 'x': rtld_printf("%p", needed->obj ? needed->obj->mapbase : 0); break; } break; } ++fmt; } } } } /* * Unload a dlopened object and its dependencies from memory and from * our data structures. It is assumed that the DAG rooted in the * object has already been unreferenced, and that the object has a * reference count of 0. */ static void unload_object(Obj_Entry *root) { Obj_Entry *obj; Obj_Entry **linkp; assert(root->refcount == 0); /* * Pass over the DAG removing unreferenced objects from * appropriate lists. */ unlink_object(root); /* Unmap all objects that are no longer referenced. */ linkp = &obj_list->next; while ((obj = *linkp) != NULL) { if (obj->refcount == 0) { LD_UTRACE(UTRACE_UNLOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0, obj->path); dbg("unloading \"%s\"", obj->path); unload_filtees(root); munmap(obj->mapbase, obj->mapsize); linkmap_delete(obj); *linkp = obj->next; obj_count--; obj_free(obj); } else linkp = &obj->next; } obj_tail = linkp; } static void unlink_object(Obj_Entry *root) { Objlist_Entry *elm; if (root->refcount == 0) { /* Remove the object from the RTLD_GLOBAL list. */ objlist_remove(&list_global, root); /* Remove the object from all objects' DAG lists. */ STAILQ_FOREACH(elm, &root->dagmembers, link) { objlist_remove(&elm->obj->dldags, root); if (elm->obj != root) unlink_object(elm->obj); } } } static void ref_dag(Obj_Entry *root) { Objlist_Entry *elm; assert(root->dag_inited); STAILQ_FOREACH(elm, &root->dagmembers, link) elm->obj->refcount++; } static void unref_dag(Obj_Entry *root) { Objlist_Entry *elm; assert(root->dag_inited); STAILQ_FOREACH(elm, &root->dagmembers, link) elm->obj->refcount--; } /* * Common code for MD __tls_get_addr(). */ void * tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset) { Elf_Addr* dtv = *dtvp; RtldLockState lockstate; /* Check dtv generation in case new modules have arrived */ if (dtv[0] != tls_dtv_generation) { Elf_Addr* newdtv; int to_copy; wlock_acquire(rtld_bind_lock, &lockstate); newdtv = xcalloc(tls_max_index + 2, sizeof(Elf_Addr)); to_copy = dtv[1]; if (to_copy > tls_max_index) to_copy = tls_max_index; memcpy(&newdtv[2], &dtv[2], to_copy * sizeof(Elf_Addr)); newdtv[0] = tls_dtv_generation; newdtv[1] = tls_max_index; free(dtv); cpu_sfence(); dtv = *dtvp = newdtv; lock_release(rtld_bind_lock, &lockstate); } /* Dynamically allocate module TLS if necessary */ if (!dtv[index + 1]) { /* Signal safe, wlock will block out signals. */ wlock_acquire(rtld_bind_lock, &lockstate); dtv = *dtvp; if (!dtv[index + 1]) dtv[index + 1] = (Elf_Addr)allocate_module_tls(index); lock_release(rtld_bind_lock, &lockstate); } return ((void *)(dtv[index + 1] + offset)); } #if defined(RTLD_STATIC_TLS_VARIANT_II) /* * Allocate the static TLS area. Return a pointer to the TCB. The * static area is based on negative offsets relative to the tcb. * * The TCB contains an errno pointer for the system call layer, but because * we are the RTLD we really have no idea how the caller was compiled so * the information has to be passed in. errno can either be: * * type 0 errno is a simple non-TLS global pointer. * (special case for e.g. libc_rtld) * type 1 errno accessed by GOT entry (dynamically linked programs) * type 2 errno accessed by %gs:OFFSET (statically linked programs) */ struct tls_tcb * allocate_tls(Obj_Entry *objs) { Obj_Entry *obj; size_t data_size; size_t dtv_size; struct tls_tcb *tcb; Elf_Addr *dtv; Elf_Addr addr; /* * Allocate the new TCB. static TLS storage is placed just before the * TCB to support the %gs:OFFSET (negative offset) model. */ data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) & ~RTLD_STATIC_TLS_ALIGN_MASK; tcb = malloc(data_size + sizeof(*tcb)); tcb = (void *)((char *)tcb + data_size); /* actual tcb location */ dtv_size = (tls_max_index + 2) * sizeof(Elf_Addr); dtv = malloc(dtv_size); bzero(dtv, dtv_size); #ifdef RTLD_TCB_HAS_SELF_POINTER tcb->tcb_self = tcb; #endif tcb->tcb_dtv = dtv; tcb->tcb_pthread = NULL; dtv[0] = tls_dtv_generation; dtv[1] = tls_max_index; for (obj = objs; obj; obj = obj->next) { if (obj->tlsoffset) { addr = (Elf_Addr)tcb - obj->tlsoffset; memset((void *)(addr + obj->tlsinitsize), 0, obj->tlssize - obj->tlsinitsize); if (obj->tlsinit) { memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize); obj->static_tls_copied = true; } dtv[obj->tlsindex + 1] = addr; } } return(tcb); } void free_tls(struct tls_tcb *tcb) { Elf_Addr *dtv; int dtv_size, i; Elf_Addr tls_start, tls_end; size_t data_size; data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) & ~RTLD_STATIC_TLS_ALIGN_MASK; dtv = tcb->tcb_dtv; dtv_size = dtv[1]; tls_end = (Elf_Addr)tcb; tls_start = (Elf_Addr)tcb - data_size; for (i = 0; i < dtv_size; i++) { if (dtv[i+2] != 0 && (dtv[i+2] < tls_start || dtv[i+2] > tls_end)) { free((void *)dtv[i+2]); } } free(dtv); free((void*) tls_start); } #else #error "Unsupported TLS layout" #endif /* * Allocate TLS block for module with given index. */ void * allocate_module_tls(int index) { Obj_Entry* obj; char* p; for (obj = obj_list; obj; obj = obj->next) { if (obj->tlsindex == index) break; } if (!obj) { _rtld_error("Can't find module with TLS index %d", index); die(); } if (obj->tls_static) { #if defined(RTLD_STATIC_TLS_VARIANT_II) p = (char *)tls_get_tcb() - obj->tlsoffset; #else #error "Unsupported TLS layout" #endif return p; } p = malloc(obj->tlssize); if (p == NULL) { _rtld_error("Cannot allocate TLS block for index %d", index); die(); } memcpy(p, obj->tlsinit, obj->tlsinitsize); memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize); return p; } bool allocate_tls_offset(Obj_Entry *obj) { size_t off; if (obj->tls_static) return true; if (obj->tls_dynamic) return false; if (obj->tlssize == 0) { obj->tls_static = true; return true; } if (obj->tlsindex == 1) off = calculate_first_tls_offset(obj->tlssize, obj->tlsalign); else off = calculate_tls_offset(tls_last_offset, tls_last_size, obj->tlssize, obj->tlsalign); /* * If we have already fixed the size of the static TLS block, we * must stay within that size. When allocating the static TLS, we * leave a small amount of space spare to be used for dynamically * loading modules which use static TLS. */ if (tls_static_space) { if (calculate_tls_end(off, obj->tlssize) > tls_static_space) return false; } tls_last_offset = obj->tlsoffset = off; tls_last_size = obj->tlssize; obj->tls_static = true; return true; } void free_tls_offset(Obj_Entry *obj) { #ifdef RTLD_STATIC_TLS_VARIANT_II /* * If we were the last thing to allocate out of the static TLS * block, we give our space back to the 'allocator'. This is a * simplistic workaround to allow libGL.so.1 to be loaded and * unloaded multiple times. We only handle the Variant II * mechanism for now - this really needs a proper allocator. */ if (calculate_tls_end(obj->tlsoffset, obj->tlssize) == calculate_tls_end(tls_last_offset, tls_last_size)) { tls_last_offset -= obj->tlssize; tls_last_size = 0; } #endif } struct tls_tcb * _rtld_allocate_tls(void) { struct tls_tcb *new_tcb; RtldLockState lockstate; wlock_acquire(rtld_bind_lock, &lockstate); new_tcb = allocate_tls(obj_list); lock_release(rtld_bind_lock, &lockstate); return (new_tcb); } void _rtld_free_tls(struct tls_tcb *tcb) { RtldLockState lockstate; wlock_acquire(rtld_bind_lock, &lockstate); free_tls(tcb); lock_release(rtld_bind_lock, &lockstate); } static void object_add_name(Obj_Entry *obj, const char *name) { Name_Entry *entry; size_t len; len = strlen(name); entry = malloc(sizeof(Name_Entry) + len); if (entry != NULL) { strcpy(entry->name, name); STAILQ_INSERT_TAIL(&obj->names, entry, link); } } static int object_match_name(const Obj_Entry *obj, const char *name) { Name_Entry *entry; STAILQ_FOREACH(entry, &obj->names, link) { if (strcmp(name, entry->name) == 0) return (1); } return (0); } static Obj_Entry * locate_dependency(const Obj_Entry *obj, const char *name) { const Objlist_Entry *entry; const Needed_Entry *needed; STAILQ_FOREACH(entry, &list_main, link) { if (object_match_name(entry->obj, name)) return entry->obj; } for (needed = obj->needed; needed != NULL; needed = needed->next) { if (strcmp(obj->strtab + needed->name, name) == 0 || (needed->obj != NULL && object_match_name(needed->obj, name))) { /* * If there is DT_NEEDED for the name we are looking for, * we are all set. Note that object might not be found if * dependency was not loaded yet, so the function can * return NULL here. This is expected and handled * properly by the caller. */ return (needed->obj); } } _rtld_error("%s: Unexpected inconsistency: dependency %s not found", obj->path, name); die(); } static int check_object_provided_version(Obj_Entry *refobj, const Obj_Entry *depobj, const Elf_Vernaux *vna) { const Elf_Verdef *vd; const char *vername; vername = refobj->strtab + vna->vna_name; vd = depobj->verdef; if (vd == NULL) { _rtld_error("%s: version %s required by %s not defined", depobj->path, vername, refobj->path); return (-1); } for (;;) { if (vd->vd_version != VER_DEF_CURRENT) { _rtld_error("%s: Unsupported version %d of Elf_Verdef entry", depobj->path, vd->vd_version); return (-1); } if (vna->vna_hash == vd->vd_hash) { const Elf_Verdaux *aux = (const Elf_Verdaux *) ((char *)vd + vd->vd_aux); if (strcmp(vername, depobj->strtab + aux->vda_name) == 0) return (0); } if (vd->vd_next == 0) break; vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next); } if (vna->vna_flags & VER_FLG_WEAK) return (0); _rtld_error("%s: version %s required by %s not found", depobj->path, vername, refobj->path); return (-1); } static int rtld_verify_object_versions(Obj_Entry *obj) { const Elf_Verneed *vn; const Elf_Verdef *vd; const Elf_Verdaux *vda; const Elf_Vernaux *vna; const Obj_Entry *depobj; int maxvernum, vernum; if (obj->ver_checked) return (0); obj->ver_checked = true; maxvernum = 0; /* * Walk over defined and required version records and figure out * max index used by any of them. Do very basic sanity checking * while there. */ vn = obj->verneed; while (vn != NULL) { if (vn->vn_version != VER_NEED_CURRENT) { _rtld_error("%s: Unsupported version %d of Elf_Verneed entry", obj->path, vn->vn_version); return (-1); } vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux); for (;;) { vernum = VER_NEED_IDX(vna->vna_other); if (vernum > maxvernum) maxvernum = vernum; if (vna->vna_next == 0) break; vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next); } if (vn->vn_next == 0) break; vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next); } vd = obj->verdef; while (vd != NULL) { if (vd->vd_version != VER_DEF_CURRENT) { _rtld_error("%s: Unsupported version %d of Elf_Verdef entry", obj->path, vd->vd_version); return (-1); } vernum = VER_DEF_IDX(vd->vd_ndx); if (vernum > maxvernum) maxvernum = vernum; if (vd->vd_next == 0) break; vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next); } if (maxvernum == 0) return (0); /* * Store version information in array indexable by version index. * Verify that object version requirements are satisfied along the * way. */ obj->vernum = maxvernum + 1; obj->vertab = xcalloc(obj->vernum, sizeof(Ver_Entry)); vd = obj->verdef; while (vd != NULL) { if ((vd->vd_flags & VER_FLG_BASE) == 0) { vernum = VER_DEF_IDX(vd->vd_ndx); assert(vernum <= maxvernum); vda = (const Elf_Verdaux *)((char *)vd + vd->vd_aux); obj->vertab[vernum].hash = vd->vd_hash; obj->vertab[vernum].name = obj->strtab + vda->vda_name; obj->vertab[vernum].file = NULL; obj->vertab[vernum].flags = 0; } if (vd->vd_next == 0) break; vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next); } vn = obj->verneed; while (vn != NULL) { depobj = locate_dependency(obj, obj->strtab + vn->vn_file); if (depobj == NULL) return (-1); vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux); for (;;) { if (check_object_provided_version(obj, depobj, vna)) return (-1); vernum = VER_NEED_IDX(vna->vna_other); assert(vernum <= maxvernum); obj->vertab[vernum].hash = vna->vna_hash; obj->vertab[vernum].name = obj->strtab + vna->vna_name; obj->vertab[vernum].file = obj->strtab + vn->vn_file; obj->vertab[vernum].flags = (vna->vna_other & VER_NEED_HIDDEN) ? VER_INFO_HIDDEN : 0; if (vna->vna_next == 0) break; vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next); } if (vn->vn_next == 0) break; vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next); } return 0; } static int rtld_verify_versions(const Objlist *objlist) { Objlist_Entry *entry; int rc; rc = 0; STAILQ_FOREACH(entry, objlist, link) { /* * Skip dummy objects or objects that have their version requirements * already checked. */ if (entry->obj->strtab == NULL || entry->obj->vertab != NULL) continue; if (rtld_verify_object_versions(entry->obj) == -1) { rc = -1; if (ld_tracing == NULL) break; } } if (rc == 0 || ld_tracing != NULL) rc = rtld_verify_object_versions(&obj_rtld); return rc; } const Ver_Entry * fetch_ventry(const Obj_Entry *obj, unsigned long symnum) { Elf_Versym vernum; if (obj->vertab) { vernum = VER_NDX(obj->versyms[symnum]); if (vernum >= obj->vernum) { _rtld_error("%s: symbol %s has wrong verneed value %d", obj->path, obj->strtab + symnum, vernum); } else if (obj->vertab[vernum].hash != 0) { return &obj->vertab[vernum]; } } return NULL; } int _rtld_get_stack_prot(void) { return (stack_prot); } static void map_stacks_exec(RtldLockState *lockstate) { return; /* * Stack protection must be implemented in the kernel before the dynamic * linker can handle PT_GNU_STACK sections. * The following is the FreeBSD implementation of map_stacks_exec() * void (*thr_map_stacks_exec)(void); * * if ((max_stack_flags & PF_X) == 0 || (stack_prot & PROT_EXEC) != 0) * return; * thr_map_stacks_exec = (void (*)(void))(uintptr_t) * get_program_var_addr("__pthread_map_stacks_exec", lockstate); * if (thr_map_stacks_exec != NULL) { * stack_prot |= PROT_EXEC; * thr_map_stacks_exec(); * } */ } /* * Only called after all primary shared libraries are loaded (EARLY is * not set). Resolves the static TLS distribution function at first-call. * This is typically a weak libc symbol that is overrideen by the threading * library. */ static void distribute_static_tls(Objlist *list, RtldLockState *lockstate) { Objlist_Entry *elm; Obj_Entry *obj; static void (*dtlsfunc)(size_t, void *, size_t, size_t); /* * First time, resolve "_pthread_distribute_static_tls". */ if (dtlsfunc == NULL) { dtlsfunc = (void *)dlfunc(RTLD_ALL, "_pthread_distribute_static_tls"); if (dtlsfunc == NULL) return; } /* * Initialize static TLS data for the object list using the callback * function (to either libc or pthreads). */ STAILQ_FOREACH(elm, list, link) { obj = elm->obj; if (/*obj->marker ||*/ !obj->tls_static || obj->static_tls_copied) continue; dtlsfunc(obj->tlsoffset, obj->tlsinit, obj->tlsinitsize, obj->tlssize); obj->static_tls_copied = true; } } void symlook_init(SymLook *dst, const char *name) { bzero(dst, sizeof(*dst)); dst->name = name; dst->hash = elf_hash(name); dst->hash_gnu = gnu_hash(name); } static void symlook_init_from_req(SymLook *dst, const SymLook *src) { dst->name = src->name; dst->hash = src->hash; dst->hash_gnu = src->hash_gnu; dst->ventry = src->ventry; dst->flags = src->flags; dst->defobj_out = NULL; dst->sym_out = NULL; dst->lockstate = src->lockstate; } /* * Parse a file descriptor number without pulling in more of libc (e.g. atoi). */ static int parse_libdir(const char *str) { static const int RADIX = 10; /* XXXJA: possibly support hex? */ const char *orig; int fd; char c; orig = str; fd = 0; for (c = *str; c != '\0'; c = *++str) { if (c < '0' || c > '9') return (-1); fd *= RADIX; fd += c - '0'; } /* Make sure we actually parsed something. */ if (str == orig) { _rtld_error("failed to parse directory FD from '%s'", str); return (-1); } return (fd); } #ifdef ENABLE_OSRELDATE /* * Overrides for libc_pic-provided functions. */ int __getosreldate(void) { size_t len; int oid[2]; int error, osrel; if (osreldate != 0) return (osreldate); oid[0] = CTL_KERN; oid[1] = KERN_OSRELDATE; osrel = 0; len = sizeof(osrel); error = sysctl(oid, 2, &osrel, &len, NULL, 0); if (error == 0 && osrel > 0 && len == sizeof(osrel)) osreldate = osrel; return (osreldate); } #endif /* * Ask the kernel for the extra tls space to allocate after calculating * base tls requirements in rtld-elf. 5.9 or later. */ static int __getstatictlsextra(void) { size_t len; int oid[2]; int error; int tls_extra; oid[0] = CTL_KERN; oid[1] = KERN_STATIC_TLS_EXTRA; len = sizeof(tls_extra); error = sysctl(oid, 2, &tls_extra, &len, NULL, 0); if (error || len != sizeof(tls_extra)) tls_extra = RTLD_STATIC_TLS_EXTRA_DEFAULT; if (tls_extra < RTLD_STATIC_TLS_EXTRA_MIN) tls_extra = RTLD_STATIC_TLS_EXTRA_MIN; if (tls_extra > RTLD_STATIC_TLS_EXTRA_MAX) tls_extra = RTLD_STATIC_TLS_EXTRA_MAX; return tls_extra; } /* * No unresolved symbols for rtld. */ void __pthread_cxa_finalize(struct dl_phdr_info *a) { } const char * rtld_strerror(int errnum) { if (errnum < 0 || errnum >= sys_nerr) return ("Unknown error"); return (sys_errlist[errnum]); }