/* $OpenBSD: vfs_getcwd.c,v 1.38 2022/12/05 23:18:37 deraadt Exp $ */ /* $NetBSD: vfs_getcwd.c,v 1.3.2.3 1999/07/11 10:24:09 sommerfeld Exp $ */ /* * Copyright (c) 1999 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Bill Sommerfeld. * * 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 NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``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 FOUNDATION OR CONTRIBUTORS * 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. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* only for DIRBLKSIZ */ #include /* Find parent vnode of *lvpp, return in *uvpp */ int vfs_getcwd_scandir(struct vnode **lvpp, struct vnode **uvpp, char **bpp, char *bufp, struct proc *p) { int eofflag, tries, dirbuflen = 0, len, reclen, error = 0; off_t off; struct uio uio; struct iovec iov; char *dirbuf = NULL; ino_t fileno; struct vattr va; struct vnode *uvp = NULL; struct vnode *lvp = *lvpp; struct componentname cn; tries = 0; /* * If we want the filename, get some info we need while the * current directory is still locked. */ if (bufp != NULL) { error = VOP_GETATTR(lvp, &va, p->p_ucred, p); if (error) { vput(lvp); *lvpp = NULL; *uvpp = NULL; return (error); } } cn.cn_nameiop = LOOKUP; cn.cn_flags = ISLASTCN | ISDOTDOT | RDONLY; cn.cn_proc = p; cn.cn_cred = p->p_ucred; cn.cn_pnbuf = NULL; cn.cn_nameptr = ".."; cn.cn_namelen = 2; cn.cn_consume = 0; /* Get parent vnode using lookup of '..' */ error = VOP_LOOKUP(lvp, uvpp, &cn); if (error) { vput(lvp); *lvpp = NULL; *uvpp = NULL; return (error); } uvp = *uvpp; /* If we don't care about the pathname, we're done */ if (bufp == NULL) { error = 0; goto out; } fileno = va.va_fileid; dirbuflen = DIRBLKSIZ; if (dirbuflen < va.va_blocksize) dirbuflen = va.va_blocksize; /* XXX we need some limit for fuse, 1 MB should be enough */ if (dirbuflen > 0xfffff) { error = EINVAL; goto out; } dirbuf = malloc(dirbuflen, M_TEMP, M_WAITOK); off = 0; do { char *cpos; struct dirent *dp; iov.iov_base = dirbuf; iov.iov_len = dirbuflen; uio.uio_iov = &iov; uio.uio_iovcnt = 1; uio.uio_offset = off; uio.uio_resid = dirbuflen; uio.uio_segflg = UIO_SYSSPACE; uio.uio_rw = UIO_READ; uio.uio_procp = p; eofflag = 0; /* Call VOP_READDIR of parent */ error = VOP_READDIR(uvp, &uio, p->p_ucred, &eofflag); off = uio.uio_offset; /* Try again if NFS tosses its cookies */ if (error == EINVAL && tries < 3) { tries++; off = 0; continue; } else if (error) { goto out; /* Old userland getcwd() behaviour */ } cpos = dirbuf; tries = 0; /* Scan directory page looking for matching vnode */ for (len = (dirbuflen - uio.uio_resid); len > 0; len -= reclen) { dp = (struct dirent *)cpos; reclen = dp->d_reclen; /* Check for malformed directory */ if (reclen < DIRENT_RECSIZE(1) || reclen > len) { error = EINVAL; goto out; } if (dp->d_fileno == fileno) { char *bp = *bpp; if (offsetof(struct dirent, d_name) + dp->d_namlen > reclen) { error = EINVAL; goto out; } bp -= dp->d_namlen; if (bp <= bufp) { error = ERANGE; goto out; } memmove(bp, dp->d_name, dp->d_namlen); error = 0; *bpp = bp; goto out; } cpos += reclen; } } while (!eofflag); error = ENOENT; out: vrele(lvp); *lvpp = NULL; free(dirbuf, M_TEMP, dirbuflen); return (error); } /* Do a lookup in the vnode-to-name reverse */ int vfs_getcwd_getcache(struct vnode **lvpp, struct vnode **uvpp, char **bpp, char *bufp) { struct vnode *lvp, *uvp = NULL; char *obp; int error, vpid; lvp = *lvpp; obp = *bpp; /* Save original position to restore to on error */ error = cache_revlookup(lvp, uvpp, bpp, bufp); if (error) { if (error != -1) { vput(lvp); *lvpp = NULL; *uvpp = NULL; } return (error); } uvp = *uvpp; vpid = uvp->v_id; /* Release current lock before acquiring the parent lock */ VOP_UNLOCK(lvp); error = vget(uvp, LK_EXCLUSIVE | LK_RETRY); if (error) *uvpp = NULL; /* * Verify that vget() succeeded, and check that vnode capability * didn't change while we were waiting for the lock. */ if (error || (vpid != uvp->v_id)) { /* * Try to get our lock back. If that works, tell the caller to * try things the hard way, otherwise give up. */ if (!error) vput(uvp); *uvpp = NULL; error = vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY); if (!error) { *bpp = obp; /* restore the buffer */ return (-1); } } vrele(lvp); *lvpp = NULL; return (error); } /* Common routine shared by sys___getcwd() and vn_isunder() and sys___realpath() */ int vfs_getcwd_common(struct vnode *lvp, struct vnode *rvp, char **bpp, char *bufp, int limit, int flags, struct proc *p) { struct filedesc *fdp = p->p_fd; struct vnode *uvp = NULL; char *bp = NULL; int error, perms = VEXEC; if (rvp == NULL) { rvp = fdp->fd_rdir; if (rvp == NULL) rvp = rootvnode; } vref(rvp); vref(lvp); error = vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY); if (error) { vrele(lvp); lvp = NULL; goto out; } if (bufp) bp = *bpp; if (lvp == rvp) { if (bp) *(--bp) = '/'; goto out; } /* * This loop will terminate when we hit the root, VOP_READDIR() or * VOP_LOOKUP() fails, or we run out of space in the user buffer. */ do { if (lvp->v_type != VDIR) { error = ENOTDIR; goto out; } /* Check for access if caller cares */ if (flags & GETCWD_CHECK_ACCESS) { error = VOP_ACCESS(lvp, perms, p->p_ucred, p); if (error) goto out; perms = VEXEC|VREAD; } /* Step up if we're a covered vnode */ while (lvp->v_flag & VROOT) { struct vnode *tvp; if (lvp == rvp) goto out; tvp = lvp; lvp = lvp->v_mount->mnt_vnodecovered; vput(tvp); if (lvp == NULL) { error = ENOENT; goto out; } vref(lvp); error = vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY); if (error) { vrele(lvp); lvp = NULL; goto out; } } /* Look in the name cache */ error = vfs_getcwd_getcache(&lvp, &uvp, &bp, bufp); if (error == -1) { /* If that fails, look in the directory */ error = vfs_getcwd_scandir(&lvp, &uvp, &bp, bufp, p); } if (error) goto out; #ifdef DIAGNOSTIC if (lvp != NULL) panic("getcwd: oops, forgot to null lvp"); if (bufp && (bp <= bufp)) { panic("getcwd: oops, went back too far"); } #endif if (bp) *(--bp) = '/'; lvp = uvp; uvp = NULL; limit--; } while ((lvp != rvp) && (limit > 0)); out: if (bpp) *bpp = bp; if (uvp) vput(uvp); if (lvp) vput(lvp); vrele(rvp); return (error); } /* Find pathname of a process's current directory */ int sys___getcwd(struct proc *p, void *v, register_t *retval) { struct sys___getcwd_args *uap = v; int error, len = SCARG(uap, len); char *path, *bp; if (len > MAXPATHLEN * 4) len = MAXPATHLEN * 4; else if (len < 2) return (ERANGE); path = malloc(len, M_TEMP, M_WAITOK); bp = &path[len - 1]; *bp = '\0'; /* * 5th argument here is "max number of vnodes to traverse". * Since each entry takes up at least 2 bytes in the output * buffer, limit it to N/2 vnodes for an N byte buffer. */ error = vfs_getcwd_common(p->p_fd->fd_cdir, NULL, &bp, path, len/2, GETCWD_CHECK_ACCESS, p); if (error) goto out; /* Put the result into user buffer */ error = copyoutstr(bp, SCARG(uap, buf), MAXPATHLEN, NULL); #ifdef KTRACE if (KTRPOINT(p, KTR_NAMEI)) ktrnamei(p, bp); #endif out: free(path, M_TEMP, len); return (error); }