/* $OpenBSD: access.c,v 1.6 2023/10/17 09:52:09 nicm Exp $ */ /**************************************************************************** * Copyright 2019-2021,2023 Thomas E. Dickey * * Copyright 1998-2011,2012 Free Software Foundation, Inc. * * * * Permission is hereby granted, free of charge, to any person obtaining a * * copy of this software and associated documentation files (the * * "Software"), to deal in the Software without restriction, including * * without limitation the rights to use, copy, modify, merge, publish, * * distribute, distribute with modifications, sublicense, and/or sell * * copies of the Software, and to permit persons to whom the Software is * * furnished to do so, subject to the following conditions: * * * * The above copyright notice and this permission notice shall be included * * in all copies or substantial portions of the Software. * * * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, * * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR * * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR * * THE USE OR OTHER DEALINGS IN THE SOFTWARE. * * * * Except as contained in this notice, the name(s) of the above copyright * * holders shall not be used in advertising or otherwise to promote the * * sale, use or other dealings in this Software without prior written * * authorization. * ****************************************************************************/ /**************************************************************************** * Author: Thomas E. Dickey * ****************************************************************************/ #include #include #ifndef USE_ROOT_ACCESS #if HAVE_SETFSUID #include #else #include #endif #endif #if HAVE_GETAUXVAL && HAVE_SYS_AUXV_H && defined(__GLIBC__) && (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 19) #include #define USE_GETAUXVAL 1 #else #define USE_GETAUXVAL 0 #endif #include MODULE_ID("$Id: access.c,v 1.6 2023/10/17 09:52:09 nicm Exp $") #define LOWERCASE(c) ((isalpha(UChar(c)) && isupper(UChar(c))) ? tolower(UChar(c)) : (c)) #ifdef _NC_MSC # define ACCESS(FN, MODE) access((FN), (MODE)&(R_OK|W_OK)) #else # define ACCESS access #endif NCURSES_EXPORT(char *) _nc_rootname(char *path) { char *result = _nc_basename(path); #if !MIXEDCASE_FILENAMES || defined(PROG_EXT) static char *temp; char *s; if ((temp = strdup(result)) != 0) result = temp; #if !MIXEDCASE_FILENAMES for (s = result; *s != '\0'; ++s) { *s = (char) LOWERCASE(*s); } #endif #if defined(PROG_EXT) if ((s = strrchr(result, '.')) != 0) { if (!strcmp(s, PROG_EXT)) *s = '\0'; } #endif #endif return result; } /* * Check if a string appears to be an absolute pathname. */ NCURSES_EXPORT(bool) _nc_is_abs_path(const char *path) { #if defined(__EMX__) || defined(__DJGPP__) #define is_pathname(s) ((((s) != 0) && ((s)[0] == '/')) \ || (((s)[0] != 0) && ((s)[1] == ':'))) #else #define is_pathname(s) ((s) != 0 && (s)[0] == '/') #endif return is_pathname(path); } /* * Return index of the basename */ NCURSES_EXPORT(unsigned) _nc_pathlast(const char *path) { const char *test = strrchr(path, '/'); #ifdef __EMX__ if (test == 0) test = strrchr(path, '\\'); #endif if (test == 0) test = path; else test++; return (unsigned) (test - path); } NCURSES_EXPORT(char *) _nc_basename(char *path) { return path + _nc_pathlast(path); } NCURSES_EXPORT(int) _nc_access(const char *path, int mode) { int result; if (path == 0) { result = -1; } else if (ACCESS(path, mode) < 0) { if ((mode & W_OK) != 0 && errno == ENOENT && strlen(path) < PATH_MAX) { char head[PATH_MAX]; char *leaf; _nc_STRCPY(head, path, sizeof(head)); leaf = _nc_basename(head); if (leaf == 0) leaf = head; *leaf = '\0'; if (head == leaf) _nc_STRCPY(head, ".", sizeof(head)); result = ACCESS(head, R_OK | W_OK | X_OK); } else { result = -1; } } else { result = 0; } return result; } NCURSES_EXPORT(bool) _nc_is_dir_path(const char *path) { bool result = FALSE; struct stat sb; if (stat(path, &sb) == 0 && S_ISDIR(sb.st_mode)) { result = TRUE; } return result; } NCURSES_EXPORT(bool) _nc_is_file_path(const char *path) { bool result = FALSE; struct stat sb; if (stat(path, &sb) == 0 && S_ISREG(sb.st_mode)) { result = TRUE; } return result; } #if HAVE_GETEUID && HAVE_GETEGID #define is_posix_elevated() \ (getuid() != geteuid() \ || getgid() != getegid()) #else #define is_posix_elevated() FALSE #endif #if HAVE_ISSETUGID #define is_elevated() issetugid() #elif USE_GETAUXVAL && defined(AT_SECURE) #define is_elevated() \ (getauxval(AT_SECURE) \ ? TRUE \ : (errno != ENOENT \ ? FALSE \ : is_posix_elevated())) #else #define is_elevated() is_posix_elevated() #endif #if HAVE_SETFSUID #define lower_privileges() \ int save_err = errno; \ setfsuid(getuid()); \ setfsgid(getgid()); \ errno = save_err #define resume_elevation() \ save_err = errno; \ setfsuid(geteuid()); \ setfsgid(getegid()); \ errno = save_err #else #define lower_privileges() /* nothing */ #define resume_elevation() /* nothing */ #endif /* * Returns true if not running as root or setuid. We use this check to allow * applications to use environment variables that are used for searching lists * of directories, etc. */ NCURSES_EXPORT(int) _nc_env_access(void) { int result = TRUE; #if HAVE_GETUID && HAVE_GETEUID #if !defined(USE_SETUID_ENVIRON) if (is_elevated()) { result = FALSE; } #endif #if !defined(USE_ROOT_ENVIRON) if ((getuid() == ROOT_UID) || (geteuid() == ROOT_UID)) { result = FALSE; } #endif #endif /* HAVE_GETUID && HAVE_GETEUID */ return result; } #ifndef USE_ROOT_ACCESS /* * Limit privileges if possible; otherwise disallow access for updating files. */ NCURSES_EXPORT(FILE *) _nc_safe_fopen(const char *path, const char *mode) { FILE *result = NULL; #if HAVE_SETFSUID lower_privileges(); result = fopen(path, mode); resume_elevation(); #else if (!is_elevated() || *mode == 'r') { result = fopen(path, mode); } #endif return result; } NCURSES_EXPORT(int) _nc_safe_open3(const char *path, int flags, mode_t mode) { int result = -1; #if HAVE_SETFSUID lower_privileges(); result = open(path, flags, mode); resume_elevation(); #else if (!is_elevated() || (flags & O_RDONLY)) { result = open(path, flags, mode); } #endif return result; } #endif /* USE_ROOT_ACCESS */