/* SPDX-License-Identifier: LGPL-2.1-or-later */ #include #include "alloc-util.h" #include "chase.h" #include "fd-util.h" #include "fileio.h" #include "fs-util.h" #include "glyph-util.h" #include "log.h" #include "path-util.h" #include "string-util.h" #include "user-util.h" bool unsafe_transition(const struct stat *a, const struct stat *b) { /* Returns true if the transition from a to b is safe, i.e. that we never transition from unprivileged to * privileged files or directories. Why bother? So that unprivileged code can't symlink to privileged files * making us believe we read something safe even though it isn't safe in the specific context we open it in. */ if (a->st_uid == 0) /* Transitioning from privileged to unprivileged is always fine */ return false; return a->st_uid != b->st_uid; /* Otherwise we need to stay within the same UID */ } static int log_unsafe_transition(int a, int b, const char *path, ChaseFlags flags) { _cleanup_free_ char *n1 = NULL, *n2 = NULL, *user_a = NULL, *user_b = NULL; struct stat st; if (!FLAGS_SET(flags, CHASE_WARN)) return -ENOLINK; (void) fd_get_path(a, &n1); (void) fd_get_path(b, &n2); if (fstat(a, &st) == 0) user_a = uid_to_name(st.st_uid); if (fstat(b, &st) == 0) user_b = uid_to_name(st.st_uid); return log_warning_errno(SYNTHETIC_ERRNO(ENOLINK), "Detected unsafe path transition %s (owned by %s) %s %s (owned by %s) during canonicalization of %s.", strna(n1), strna(user_a), special_glyph(SPECIAL_GLYPH_ARROW_RIGHT), strna(n2), strna(user_b), path); } static int log_autofs_mount_point(int fd, const char *path, ChaseFlags flags) { _cleanup_free_ char *n1 = NULL; if (!FLAGS_SET(flags, CHASE_WARN)) return -EREMOTE; (void) fd_get_path(fd, &n1); return log_warning_errno(SYNTHETIC_ERRNO(EREMOTE), "Detected autofs mount point %s during canonicalization of %s.", strna(n1), path); } static int log_prohibited_symlink(int fd, ChaseFlags flags) { _cleanup_free_ char *n1 = NULL; assert(fd >= 0); if (!FLAGS_SET(flags, CHASE_WARN)) return -EREMCHG; (void) fd_get_path(fd, &n1); return log_warning_errno(SYNTHETIC_ERRNO(EREMCHG), "Detected symlink where not symlink is allowed at %s, refusing.", strna(n1)); } static int chaseat_needs_absolute(int dir_fd, const char *path) { if (dir_fd < 0) return path_is_absolute(path); return dir_fd_is_root(dir_fd); } int chaseat(int dir_fd, const char *path, ChaseFlags flags, char **ret_path, int *ret_fd) { _cleanup_free_ char *buffer = NULL, *done = NULL; _cleanup_close_ int fd = -EBADF, root_fd = -EBADF; unsigned max_follow = CHASE_MAX; /* how many symlinks to follow before giving up and returning ELOOP */ bool exists = true, append_trail_slash = false; struct stat st; /* stat obtained from fd */ const char *todo; int r; assert(!FLAGS_SET(flags, CHASE_PREFIX_ROOT)); assert(!FLAGS_SET(flags, CHASE_STEP|CHASE_EXTRACT_FILENAME)); assert(!FLAGS_SET(flags, CHASE_TRAIL_SLASH|CHASE_EXTRACT_FILENAME)); assert(!FLAGS_SET(flags, CHASE_MKDIR_0755) || (flags & (CHASE_NONEXISTENT | CHASE_PARENT)) != 0); assert(dir_fd >= 0 || dir_fd == AT_FDCWD); /* Either the file may be missing, or we return an fd to the final object, but both make no sense */ if (FLAGS_SET(flags, CHASE_NONEXISTENT)) assert(!ret_fd); if (FLAGS_SET(flags, CHASE_STEP)) assert(!ret_fd); if (isempty(path)) path = "."; /* This function resolves symlinks of the path relative to the given directory file descriptor. If * CHASE_AT_RESOLVE_IN_ROOT is specified and a directory file descriptor is provided, symlinks * are resolved relative to the given directory file descriptor. Otherwise, they are resolved * relative to the root directory of the host. * * Note that when a positive directory file descriptor is provided and CHASE_AT_RESOLVE_IN_ROOT is * specified and we find an absolute symlink, it is resolved relative to given directory file * descriptor and not the root of the host. Also, when following relative symlinks, this functions * ensures they cannot be used to "escape" the given directory file descriptor. If a positive * directory file descriptor is provided, the "path" parameter is always interpreted relative to the * given directory file descriptor, even if it is absolute. If the given directory file descriptor is * AT_FDCWD and "path" is absolute, it is interpreted relative to the root directory of the host. * * When "dir_fd" points to a non-root directory and CHASE_AT_RESOLVE_IN_ROOT is set, this function * always returns a relative path in "ret_path", even if "path" is an absolute path, because openat() * like functions generally ignore the directory fd if they are provided with an absolute path. When * CHASE_AT_RESOLVE_IN_ROOT is not set, then this returns relative path to the specified file * descriptor if all resolved symlinks are relative, otherwise absolute path will be returned. When * "dir_fd" is AT_FDCWD and "path" is an absolute path, we return an absolute path in "ret_path" * because otherwise, if the caller passes the returned relative path to another openat() like * function, it would be resolved relative to the current working directory instead of to "/". * * Summary about the result path: * - "dir_fd" points to the root directory * → result will be absolute * - "dir_fd" points to a non-root directory, and CHASE_AT_RESOLVE_IN_ROOT is set * → relative * - "dir_fd" points to a non-root directory, and CHASE_AT_RESOLVE_IN_ROOT is not set * → relative when all resolved symlinks are relative, otherwise absolute * - "dir_fd" is AT_FDCWD, and "path" is absolute * → absolute * - "dir_fd" is AT_FDCWD, and "path" is relative * → relative when all resolved symlinks are relative, otherwise absolute * * Algorithmically this operates on two path buffers: "done" are the components of the path we * already processed and resolved symlinks, "." and ".." of. "todo" are the components of the path we * still need to process. On each iteration, we move one component from "todo" to "done", processing * its special meaning each time. We always keep an O_PATH fd to the component we are currently * processing, thus keeping lookup races to a minimum. * * Suggested usage: whenever you want to canonicalize a path, use this function. Pass the absolute * path you got as-is: fully qualified and relative to your host's root. Optionally, specify the * "dir_fd" parameter to tell this function what to do when encountering a symlink with an absolute * path as directory: resolve it relative to the given directory file descriptor. * * There are five ways to invoke this function: * * 1. Without CHASE_STEP or ret_fd: in this case the path is resolved and the normalized path is * returned in `ret_path`. The return value is < 0 on error. If CHASE_NONEXISTENT is also set, 0 * is returned if the file doesn't exist, > 0 otherwise. If CHASE_NONEXISTENT is not set, >= 0 is * returned if the destination was found, -ENOENT if it wasn't. * * 2. With ret_fd: in this case the destination is opened after chasing it as O_PATH and this file * descriptor is returned as return value. This is useful to open files relative to some root * directory. Note that the returned O_PATH file descriptors must be converted into a regular one * (using fd_reopen() or such) before it can be used for reading/writing. ret_fd may not be * combined with CHASE_NONEXISTENT. * * 3. With CHASE_STEP: in this case only a single step of the normalization is executed, i.e. only * the first symlink or ".." component of the path is resolved, and the resulting path is * returned. This is useful if a caller wants to trace the path through the file system verbosely. * Returns < 0 on error, > 0 if the path is fully normalized, and == 0 for each normalization * step. This may be combined with CHASE_NONEXISTENT, in which case 1 is returned when a component * is not found. * * 4. With CHASE_SAFE: in this case the path must not contain unsafe transitions, i.e. transitions * from unprivileged to privileged files or directories. In such cases the return value is * -ENOLINK. If CHASE_WARN is also set, a warning describing the unsafe transition is emitted. * CHASE_WARN cannot be used in PID 1. * * 5. With CHASE_NO_AUTOFS: in this case if an autofs mount point is encountered, path normalization * is aborted and -EREMOTE is returned. If CHASE_WARN is also set, a warning showing the path of * the mount point is emitted. CHASE_WARN cannot be used in PID 1. */ if (FLAGS_SET(flags, CHASE_AT_RESOLVE_IN_ROOT)) { /* If we get AT_FDCWD or dir_fd points to "/", then we always resolve symlinks relative to * the host's root. Hence, CHASE_AT_RESOLVE_IN_ROOT is meaningless. */ r = dir_fd_is_root_or_cwd(dir_fd); if (r < 0) return r; if (r > 0) flags &= ~CHASE_AT_RESOLVE_IN_ROOT; } if (!(flags & (CHASE_AT_RESOLVE_IN_ROOT|CHASE_NONEXISTENT|CHASE_NO_AUTOFS|CHASE_SAFE|CHASE_STEP| CHASE_PROHIBIT_SYMLINKS|CHASE_MKDIR_0755|CHASE_PARENT)) && !ret_path && ret_fd) { /* Shortcut the ret_fd case if the caller isn't interested in the actual path and has no root * set and doesn't care about any of the other special features we provide either. */ r = openat(dir_fd, path, O_PATH|O_CLOEXEC|(FLAGS_SET(flags, CHASE_NOFOLLOW) ? O_NOFOLLOW : 0)); if (r < 0) return -errno; *ret_fd = r; return 0; } buffer = strdup(path); if (!buffer) return -ENOMEM; /* If we receive an absolute path together with AT_FDCWD, we need to return an absolute path, because * a relative path would be interpreted relative to the current working directory. Also, let's make * the result absolute when the file descriptor of the root directory is specified. */ r = chaseat_needs_absolute(dir_fd, path); if (r < 0) return r; bool need_absolute = r; if (need_absolute) { done = strdup("/"); if (!done) return -ENOMEM; } /* If a positive directory file descriptor is provided, always resolve the given path relative to it, * regardless of whether it is absolute or not. If we get AT_FDCWD, follow regular openat() * semantics, if the path is relative, resolve against the current working directory. Otherwise, * resolve against root. */ fd = openat(dir_fd, done ?: ".", O_CLOEXEC|O_DIRECTORY|O_PATH); if (fd < 0) return -errno; if (fstat(fd, &st) < 0) return -errno; /* If we get AT_FDCWD, we always resolve symlinks relative to the host's root. Only if a positive * directory file descriptor is provided we will look at CHASE_AT_RESOLVE_IN_ROOT to determine * whether to resolve symlinks in it or not. */ if (dir_fd >= 0 && FLAGS_SET(flags, CHASE_AT_RESOLVE_IN_ROOT)) root_fd = openat(dir_fd, ".", O_CLOEXEC|O_DIRECTORY|O_PATH); else root_fd = open("/", O_CLOEXEC|O_DIRECTORY|O_PATH); if (root_fd < 0) return -errno; if (FLAGS_SET(flags, CHASE_TRAIL_SLASH)) append_trail_slash = ENDSWITH_SET(buffer, "/", "/."); for (todo = buffer;;) { _cleanup_free_ char *first = NULL; _cleanup_close_ int child = -EBADF; struct stat st_child; const char *e; r = path_find_first_component(&todo, /* accept_dot_dot= */ true, &e); if (r < 0) return r; if (r == 0) { /* We reached the end. */ if (append_trail_slash) if (!strextend(&done, "/")) return -ENOMEM; break; } first = strndup(e, r); if (!first) return -ENOMEM; /* Two dots? Then chop off the last bit of what we already found out. */ if (path_equal(first, "..")) { _cleanup_free_ char *parent = NULL; _cleanup_close_ int fd_parent = -EBADF; struct stat st_parent; /* If we already are at the top, then going up will not change anything. This is * in-line with how the kernel handles this. */ if (empty_or_root(done) && FLAGS_SET(flags, CHASE_AT_RESOLVE_IN_ROOT)) { if (FLAGS_SET(flags, CHASE_STEP)) goto chased_one; continue; } fd_parent = openat(fd, "..", O_CLOEXEC|O_NOFOLLOW|O_PATH|O_DIRECTORY); if (fd_parent < 0) return -errno; if (fstat(fd_parent, &st_parent) < 0) return -errno; /* If we opened the same directory, that _may_ indicate that we're at the host root * directory. Let's confirm that in more detail with dir_fd_is_root(). And if so, * going up won't change anything. */ if (stat_inode_same(&st_parent, &st)) { r = dir_fd_is_root(fd); if (r < 0) return r; if (r > 0) { if (FLAGS_SET(flags, CHASE_STEP)) goto chased_one; continue; } } r = path_extract_directory(done, &parent); if (r >= 0) { assert(!need_absolute || path_is_absolute(parent)); free_and_replace(done, parent); } else if (r == -EDESTADDRREQ) { /* 'done' contains filename only (i.e. no slash). */ assert(!need_absolute); done = mfree(done); } else if (r == -EADDRNOTAVAIL) { /* 'done' is "/". This branch should be already handled in the above. */ assert(!FLAGS_SET(flags, CHASE_AT_RESOLVE_IN_ROOT)); assert_not_reached(); } else if (r == -EINVAL) { /* 'done' is an empty string, ends with '..', or an invalid path. */ assert(!need_absolute); assert(!FLAGS_SET(flags, CHASE_AT_RESOLVE_IN_ROOT)); if (!path_is_valid(done)) return -EINVAL; /* If we're at the top of "dir_fd", start appending ".." to "done". */ if (!path_extend(&done, "..")) return -ENOMEM; } else return r; if (FLAGS_SET(flags, CHASE_STEP)) goto chased_one; if (FLAGS_SET(flags, CHASE_SAFE) && unsafe_transition(&st, &st_parent)) return log_unsafe_transition(fd, fd_parent, path, flags); /* If the path ends on a "..", and CHASE_PARENT is specified then our current 'fd' is * the child of the returned normalized path, not the parent as requested. To correct * this we have to go *two* levels up. */ if (FLAGS_SET(flags, CHASE_PARENT) && isempty(todo)) { _cleanup_close_ int fd_grandparent = -EBADF; struct stat st_grandparent; fd_grandparent = openat(fd_parent, "..", O_CLOEXEC|O_NOFOLLOW|O_PATH|O_DIRECTORY); if (fd_grandparent < 0) return -errno; if (fstat(fd_grandparent, &st_grandparent) < 0) return -errno; if (FLAGS_SET(flags, CHASE_SAFE) && unsafe_transition(&st_parent, &st_grandparent)) return log_unsafe_transition(fd_parent, fd_grandparent, path, flags); st = st_grandparent; close_and_replace(fd, fd_grandparent); break; } /* update fd and stat */ st = st_parent; close_and_replace(fd, fd_parent); continue; } /* Otherwise let's see what this is. */ child = r = RET_NERRNO(openat(fd, first, O_CLOEXEC|O_NOFOLLOW|O_PATH)); if (r < 0) { if (r != -ENOENT) return r; if (!isempty(todo) && !path_is_safe(todo)) return r; if (FLAGS_SET(flags, CHASE_MKDIR_0755) && !isempty(todo)) { child = xopenat_full(fd, first, O_DIRECTORY|O_CREAT|O_EXCL|O_NOFOLLOW|O_CLOEXEC, /* xopen_flags = */ 0, 0755); if (child < 0) return child; } else if (FLAGS_SET(flags, CHASE_PARENT) && isempty(todo)) { if (!path_extend(&done, first)) return -ENOMEM; break; } else if (FLAGS_SET(flags, CHASE_NONEXISTENT)) { if (!path_extend(&done, first, todo)) return -ENOMEM; exists = false; break; } else return r; } if (fstat(child, &st_child) < 0) return -errno; if (FLAGS_SET(flags, CHASE_SAFE) && unsafe_transition(&st, &st_child)) return log_unsafe_transition(fd, child, path, flags); if (FLAGS_SET(flags, CHASE_NO_AUTOFS) && fd_is_fs_type(child, AUTOFS_SUPER_MAGIC) > 0) return log_autofs_mount_point(child, path, flags); if (S_ISLNK(st_child.st_mode) && !(FLAGS_SET(flags, CHASE_NOFOLLOW) && isempty(todo))) { _cleanup_free_ char *destination = NULL; if (FLAGS_SET(flags, CHASE_PROHIBIT_SYMLINKS)) return log_prohibited_symlink(child, flags); /* This is a symlink, in this case read the destination. But let's make sure we * don't follow symlinks without bounds. */ if (--max_follow <= 0) return -ELOOP; r = readlinkat_malloc(fd, first, &destination); if (r < 0) return r; if (isempty(destination)) return -EINVAL; if (path_is_absolute(destination)) { /* An absolute destination. Start the loop from the beginning, but use the * root file descriptor as base. */ safe_close(fd); fd = fd_reopen(root_fd, O_CLOEXEC|O_PATH|O_DIRECTORY); if (fd < 0) return fd; if (fstat(fd, &st) < 0) return -errno; if (FLAGS_SET(flags, CHASE_SAFE) && unsafe_transition(&st_child, &st)) return log_unsafe_transition(child, fd, path, flags); /* When CHASE_AT_RESOLVE_IN_ROOT is not set, now the chased path may be * outside of the specified dir_fd. Let's make the result absolute. */ if (!FLAGS_SET(flags, CHASE_AT_RESOLVE_IN_ROOT)) need_absolute = true; r = free_and_strdup(&done, need_absolute ? "/" : NULL); if (r < 0) return r; } /* Prefix what's left to do with what we just read, and start the loop again, but * remain in the current directory. */ if (!path_extend(&destination, todo)) return -ENOMEM; free_and_replace(buffer, destination); todo = buffer; if (FLAGS_SET(flags, CHASE_STEP)) goto chased_one; continue; } /* If this is not a symlink, then let's just add the name we read to what we already verified. */ if (!path_extend(&done, first)) return -ENOMEM; if (FLAGS_SET(flags, CHASE_PARENT) && isempty(todo)) break; /* And iterate again, but go one directory further down. */ st = st_child; close_and_replace(fd, child); } if (FLAGS_SET(flags, CHASE_PARENT)) { r = stat_verify_directory(&st); if (r < 0) return r; } if (ret_path) { if (FLAGS_SET(flags, CHASE_EXTRACT_FILENAME) && done) { _cleanup_free_ char *f = NULL; r = path_extract_filename(done, &f); if (r < 0 && r != -EADDRNOTAVAIL) return r; /* If we get EADDRNOTAVAIL we clear done and it will get reinitialized by the next block. */ free_and_replace(done, f); } if (!done) { assert(!need_absolute || FLAGS_SET(flags, CHASE_EXTRACT_FILENAME)); done = strdup(append_trail_slash ? "./" : "."); if (!done) return -ENOMEM; } *ret_path = TAKE_PTR(done); } if (ret_fd) { /* Return the O_PATH fd we currently are looking to the caller. It can translate it to a * proper fd by opening /proc/self/fd/xyz. */ assert(fd >= 0); *ret_fd = TAKE_FD(fd); } if (FLAGS_SET(flags, CHASE_STEP)) return 1; return exists; chased_one: if (ret_path) { const char *e; if (!done) { assert(!need_absolute); done = strdup(append_trail_slash ? "./" : "."); if (!done) return -ENOMEM; } /* todo may contain slashes at the beginning. */ r = path_find_first_component(&todo, /* accept_dot_dot= */ true, &e); if (r < 0) return r; if (r == 0) *ret_path = TAKE_PTR(done); else { char *c; c = path_join(done, e); if (!c) return -ENOMEM; *ret_path = c; } } return 0; } static int empty_or_root_to_null(const char **path) { int r; assert(path); /* This nullifies the input path when the path is empty or points to "/". */ if (empty_or_root(*path)) { *path = NULL; return 0; } r = path_is_root(*path); if (r < 0) return r; if (r > 0) *path = NULL; return 0; } int chase(const char *path, const char *root, ChaseFlags flags, char **ret_path, int *ret_fd) { _cleanup_free_ char *root_abs = NULL, *absolute = NULL, *p = NULL; _cleanup_close_ int fd = -EBADF, pfd = -EBADF; int r; assert(path); if (isempty(path)) return -EINVAL; r = empty_or_root_to_null(&root); if (r < 0) return r; /* A root directory of "/" or "" is identical to "/". */ if (empty_or_root(root)) { root = "/"; /* When the root directory is "/", we will drop CHASE_AT_RESOLVE_IN_ROOT in chaseat(), * hence below is not necessary, but let's shortcut. */ flags &= ~CHASE_AT_RESOLVE_IN_ROOT; } else { r = path_make_absolute_cwd(root, &root_abs); if (r < 0) return r; /* Simplify the root directory, so that it has no duplicate slashes and nothing at the * end. While we won't resolve the root path we still simplify it. */ root = path_simplify(root_abs); assert(path_is_absolute(root)); assert(!empty_or_root(root)); if (FLAGS_SET(flags, CHASE_PREFIX_ROOT)) { absolute = path_join(root, path); if (!absolute) return -ENOMEM; } flags |= CHASE_AT_RESOLVE_IN_ROOT; } if (!absolute) { r = path_make_absolute_cwd(path, &absolute); if (r < 0) return r; } path = path_startswith(absolute, root); if (!path) return log_full_errno(FLAGS_SET(flags, CHASE_WARN) ? LOG_WARNING : LOG_DEBUG, SYNTHETIC_ERRNO(ECHRNG), "Specified path '%s' is outside of specified root directory '%s', refusing to resolve.", absolute, root); fd = open(root, O_CLOEXEC|O_DIRECTORY|O_PATH); if (fd < 0) return -errno; r = chaseat(fd, path, flags & ~CHASE_PREFIX_ROOT, ret_path ? &p : NULL, ret_fd ? &pfd : NULL); if (r < 0) return r; if (ret_path) { if (!FLAGS_SET(flags, CHASE_EXTRACT_FILENAME)) { /* When "root" points to the root directory, the result of chaseat() is always * absolute, hence it is not necessary to prefix with the root. When "root" points to * a non-root directory, the result path is always normalized and relative, hence * we can simply call path_join() and not necessary to call path_simplify(). * As a special case, chaseat() may return "." or "./", which are normalized too, * but we need to drop "." before merging with root. */ if (empty_or_root(root)) assert(path_is_absolute(p)); else { char *q; assert(!path_is_absolute(p)); q = path_join(root, p + STR_IN_SET(p, ".", "./")); if (!q) return -ENOMEM; free_and_replace(p, q); } } *ret_path = TAKE_PTR(p); } if (ret_fd) *ret_fd = TAKE_FD(pfd); return r; } int chaseat_prefix_root(const char *path, const char *root, char **ret) { char *q; int r; assert(path); assert(ret); /* This is mostly for prefixing the result of chaseat(). */ if (!path_is_absolute(path)) { _cleanup_free_ char *root_abs = NULL; r = empty_or_root_to_null(&root); if (r < 0 && r != -ENOENT) return r; /* If the dir_fd points to the root directory, chaseat() always returns an absolute path. */ if (empty_or_root(root)) return -EINVAL; r = path_make_absolute_cwd(root, &root_abs); if (r < 0) return r; root = path_simplify(root_abs); q = path_join(root, path + (path[0] == '.' && IN_SET(path[1], '/', '\0'))); } else q = strdup(path); if (!q) return -ENOMEM; *ret = q; return 0; } int chase_extract_filename(const char *path, const char *root, char **ret) { int r; /* This is similar to path_extract_filename(), but takes root directory. * The result should be consistent with chase() with CHASE_EXTRACT_FILENAME. */ assert(path); assert(ret); if (isempty(path)) return -EINVAL; if (!path_is_absolute(path)) return -EINVAL; r = empty_or_root_to_null(&root); if (r < 0 && r != -ENOENT) return r; if (!empty_or_root(root)) { _cleanup_free_ char *root_abs = NULL; r = path_make_absolute_cwd(root, &root_abs); if (r < 0) return r; path = path_startswith(path, root_abs); if (!path) return -EINVAL; } if (!isempty(path)) { r = path_extract_filename(path, ret); if (r != -EADDRNOTAVAIL) return r; } char *fname = strdup("."); if (!fname) return -ENOMEM; *ret = fname; return 0; } int chase_and_open(const char *path, const char *root, ChaseFlags chase_flags, int open_flags, char **ret_path) { _cleanup_close_ int path_fd = -EBADF; _cleanup_free_ char *p = NULL, *fname = NULL; mode_t mode = open_flags & O_DIRECTORY ? 0755 : 0644; int r; assert(!(chase_flags & (CHASE_NONEXISTENT|CHASE_STEP))); if (empty_or_root(root) && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE|CHASE_PROHIBIT_SYMLINKS|CHASE_PARENT|CHASE_MKDIR_0755)) == 0) /* Shortcut this call if none of the special features of this call are requested */ return xopenat_full(AT_FDCWD, path, open_flags | (FLAGS_SET(chase_flags, CHASE_NOFOLLOW) ? O_NOFOLLOW : 0), /* xopen_flags = */ 0, mode); r = chase(path, root, CHASE_PARENT|chase_flags, &p, &path_fd); if (r < 0) return r; assert(path_fd >= 0); if (!FLAGS_SET(chase_flags, CHASE_PARENT) && !FLAGS_SET(chase_flags, CHASE_EXTRACT_FILENAME)) { r = chase_extract_filename(p, root, &fname); if (r < 0) return r; } r = xopenat_full(path_fd, strempty(fname), open_flags|O_NOFOLLOW, /* xopen_flags = */ 0, mode); if (r < 0) return r; if (ret_path) *ret_path = TAKE_PTR(p); return r; } int chase_and_opendir(const char *path, const char *root, ChaseFlags chase_flags, char **ret_path, DIR **ret_dir) { _cleanup_close_ int path_fd = -EBADF; _cleanup_free_ char *p = NULL; DIR *d; int r; assert(!(chase_flags & (CHASE_NONEXISTENT|CHASE_STEP))); assert(ret_dir); if (empty_or_root(root) && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE|CHASE_PROHIBIT_SYMLINKS|CHASE_PARENT|CHASE_MKDIR_0755)) == 0) { /* Shortcut this call if none of the special features of this call are requested */ d = opendir(path); if (!d) return -errno; *ret_dir = d; return 0; } r = chase(path, root, chase_flags, ret_path ? &p : NULL, &path_fd); if (r < 0) return r; assert(path_fd >= 0); d = xopendirat(path_fd, ".", O_NOFOLLOW); if (!d) return -errno; if (ret_path) *ret_path = TAKE_PTR(p); *ret_dir = d; return 0; } int chase_and_stat(const char *path, const char *root, ChaseFlags chase_flags, char **ret_path, struct stat *ret_stat) { _cleanup_close_ int path_fd = -EBADF; _cleanup_free_ char *p = NULL; int r; assert(path); assert(!(chase_flags & (CHASE_NONEXISTENT|CHASE_STEP))); assert(ret_stat); if (empty_or_root(root) && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE|CHASE_PROHIBIT_SYMLINKS|CHASE_PARENT|CHASE_MKDIR_0755)) == 0) /* Shortcut this call if none of the special features of this call are requested */ return RET_NERRNO(fstatat(AT_FDCWD, path, ret_stat, FLAGS_SET(chase_flags, CHASE_NOFOLLOW) ? AT_SYMLINK_NOFOLLOW : 0)); r = chase(path, root, chase_flags, ret_path ? &p : NULL, &path_fd); if (r < 0) return r; assert(path_fd >= 0); if (fstat(path_fd, ret_stat) < 0) return -errno; if (ret_path) *ret_path = TAKE_PTR(p); return 0; } int chase_and_access(const char *path, const char *root, ChaseFlags chase_flags, int access_mode, char **ret_path) { _cleanup_close_ int path_fd = -EBADF; _cleanup_free_ char *p = NULL; int r; assert(path); assert(!(chase_flags & (CHASE_NONEXISTENT|CHASE_STEP))); if (empty_or_root(root) && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE|CHASE_PROHIBIT_SYMLINKS|CHASE_PARENT|CHASE_MKDIR_0755)) == 0) /* Shortcut this call if none of the special features of this call are requested */ return RET_NERRNO(faccessat(AT_FDCWD, path, access_mode, FLAGS_SET(chase_flags, CHASE_NOFOLLOW) ? AT_SYMLINK_NOFOLLOW : 0)); r = chase(path, root, chase_flags, ret_path ? &p : NULL, &path_fd); if (r < 0) return r; assert(path_fd >= 0); r = access_fd(path_fd, access_mode); if (r < 0) return r; if (ret_path) *ret_path = TAKE_PTR(p); return 0; } int chase_and_fopen_unlocked( const char *path, const char *root, ChaseFlags chase_flags, const char *open_flags, char **ret_path, FILE **ret_file) { _cleanup_free_ char *final_path = NULL; _cleanup_close_ int fd = -EBADF; int mode_flags, r; assert(path); assert(!(chase_flags & (CHASE_NONEXISTENT|CHASE_STEP|CHASE_PARENT))); assert(open_flags); assert(ret_file); mode_flags = fopen_mode_to_flags(open_flags); if (mode_flags < 0) return mode_flags; fd = chase_and_open(path, root, chase_flags, mode_flags, ret_path ? &final_path : NULL); if (fd < 0) return fd; r = take_fdopen_unlocked(&fd, open_flags, ret_file); if (r < 0) return r; if (ret_path) *ret_path = TAKE_PTR(final_path); return 0; } int chase_and_unlink(const char *path, const char *root, ChaseFlags chase_flags, int unlink_flags, char **ret_path) { _cleanup_free_ char *p = NULL, *fname = NULL; _cleanup_close_ int fd = -EBADF; int r; assert(path); assert(!(chase_flags & (CHASE_NONEXISTENT|CHASE_STEP|CHASE_PARENT))); fd = chase_and_open(path, root, chase_flags|CHASE_PARENT|CHASE_NOFOLLOW, O_PATH|O_DIRECTORY|O_CLOEXEC, &p); if (fd < 0) return fd; r = path_extract_filename(p, &fname); if (r < 0) return r; if (unlinkat(fd, fname, unlink_flags) < 0) return -errno; if (ret_path) *ret_path = TAKE_PTR(p); return 0; } int chase_and_open_parent(const char *path, const char *root, ChaseFlags chase_flags, char **ret_filename) { int pfd, r; assert(!(chase_flags & (CHASE_NONEXISTENT|CHASE_STEP))); r = chase(path, root, CHASE_PARENT|CHASE_EXTRACT_FILENAME|chase_flags, ret_filename, &pfd); if (r < 0) return r; return pfd; } int chase_and_openat(int dir_fd, const char *path, ChaseFlags chase_flags, int open_flags, char **ret_path) { _cleanup_close_ int path_fd = -EBADF; _cleanup_free_ char *p = NULL, *fname = NULL; mode_t mode = open_flags & O_DIRECTORY ? 0755 : 0644; int r; assert(!(chase_flags & (CHASE_NONEXISTENT|CHASE_STEP))); if (dir_fd == AT_FDCWD && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE|CHASE_PROHIBIT_SYMLINKS|CHASE_PARENT|CHASE_MKDIR_0755)) == 0) /* Shortcut this call if none of the special features of this call are requested */ return xopenat_full(dir_fd, path, open_flags | (FLAGS_SET(chase_flags, CHASE_NOFOLLOW) ? O_NOFOLLOW : 0), /* xopen_flags = */ 0, mode); r = chaseat(dir_fd, path, chase_flags|CHASE_PARENT, &p, &path_fd); if (r < 0) return r; if (!FLAGS_SET(chase_flags, CHASE_PARENT)) { r = path_extract_filename(p, &fname); if (r < 0 && r != -EADDRNOTAVAIL) return r; } r = xopenat_full(path_fd, strempty(fname), open_flags|O_NOFOLLOW, /* xopen_flags = */ 0, mode); if (r < 0) return r; if (ret_path) *ret_path = TAKE_PTR(p); return r; } int chase_and_opendirat(int dir_fd, const char *path, ChaseFlags chase_flags, char **ret_path, DIR **ret_dir) { _cleanup_close_ int path_fd = -EBADF; _cleanup_free_ char *p = NULL; DIR *d; int r; assert(!(chase_flags & (CHASE_NONEXISTENT|CHASE_STEP))); assert(ret_dir); if (dir_fd == AT_FDCWD && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE|CHASE_PROHIBIT_SYMLINKS|CHASE_PARENT|CHASE_MKDIR_0755)) == 0) { /* Shortcut this call if none of the special features of this call are requested */ d = opendir(path); if (!d) return -errno; *ret_dir = d; return 0; } r = chaseat(dir_fd, path, chase_flags, ret_path ? &p : NULL, &path_fd); if (r < 0) return r; assert(path_fd >= 0); d = xopendirat(path_fd, ".", O_NOFOLLOW); if (!d) return -errno; if (ret_path) *ret_path = TAKE_PTR(p); *ret_dir = d; return 0; } int chase_and_statat(int dir_fd, const char *path, ChaseFlags chase_flags, char **ret_path, struct stat *ret_stat) { _cleanup_close_ int path_fd = -EBADF; _cleanup_free_ char *p = NULL; int r; assert(path); assert(!(chase_flags & (CHASE_NONEXISTENT|CHASE_STEP))); assert(ret_stat); if (dir_fd == AT_FDCWD && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE|CHASE_PROHIBIT_SYMLINKS|CHASE_PARENT|CHASE_MKDIR_0755)) == 0) /* Shortcut this call if none of the special features of this call are requested */ return RET_NERRNO(fstatat(AT_FDCWD, path, ret_stat, FLAGS_SET(chase_flags, CHASE_NOFOLLOW) ? AT_SYMLINK_NOFOLLOW : 0)); r = chaseat(dir_fd, path, chase_flags, ret_path ? &p : NULL, &path_fd); if (r < 0) return r; assert(path_fd >= 0); if (fstat(path_fd, ret_stat) < 0) return -errno; if (ret_path) *ret_path = TAKE_PTR(p); return 0; } int chase_and_accessat(int dir_fd, const char *path, ChaseFlags chase_flags, int access_mode, char **ret_path) { _cleanup_close_ int path_fd = -EBADF; _cleanup_free_ char *p = NULL; int r; assert(path); assert(!(chase_flags & (CHASE_NONEXISTENT|CHASE_STEP))); if (dir_fd == AT_FDCWD && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE|CHASE_PROHIBIT_SYMLINKS|CHASE_PARENT|CHASE_MKDIR_0755)) == 0) /* Shortcut this call if none of the special features of this call are requested */ return RET_NERRNO(faccessat(AT_FDCWD, path, access_mode, FLAGS_SET(chase_flags, CHASE_NOFOLLOW) ? AT_SYMLINK_NOFOLLOW : 0)); r = chaseat(dir_fd, path, chase_flags, ret_path ? &p : NULL, &path_fd); if (r < 0) return r; assert(path_fd >= 0); r = access_fd(path_fd, access_mode); if (r < 0) return r; if (ret_path) *ret_path = TAKE_PTR(p); return 0; } int chase_and_fopenat_unlocked( int dir_fd, const char *path, ChaseFlags chase_flags, const char *open_flags, char **ret_path, FILE **ret_file) { _cleanup_free_ char *final_path = NULL; _cleanup_close_ int fd = -EBADF; int mode_flags, r; assert(path); assert(!(chase_flags & (CHASE_NONEXISTENT|CHASE_STEP|CHASE_PARENT))); assert(open_flags); assert(ret_file); mode_flags = fopen_mode_to_flags(open_flags); if (mode_flags < 0) return mode_flags; fd = chase_and_openat(dir_fd, path, chase_flags, mode_flags, ret_path ? &final_path : NULL); if (fd < 0) return fd; r = take_fdopen_unlocked(&fd, open_flags, ret_file); if (r < 0) return r; if (ret_path) *ret_path = TAKE_PTR(final_path); return 0; } int chase_and_unlinkat(int dir_fd, const char *path, ChaseFlags chase_flags, int unlink_flags, char **ret_path) { _cleanup_free_ char *p = NULL, *fname = NULL; _cleanup_close_ int fd = -EBADF; int r; assert(path); assert(!(chase_flags & (CHASE_NONEXISTENT|CHASE_STEP|CHASE_PARENT))); fd = chase_and_openat(dir_fd, path, chase_flags|CHASE_PARENT|CHASE_NOFOLLOW, O_PATH|O_DIRECTORY|O_CLOEXEC, &p); if (fd < 0) return fd; r = path_extract_filename(p, &fname); if (r < 0) return r; if (unlinkat(fd, fname, unlink_flags) < 0) return -errno; if (ret_path) *ret_path = TAKE_PTR(p); return 0; } int chase_and_open_parent_at(int dir_fd, const char *path, ChaseFlags chase_flags, char **ret_filename) { int pfd, r; assert(!(chase_flags & (CHASE_NONEXISTENT|CHASE_STEP))); r = chaseat(dir_fd, path, CHASE_PARENT|CHASE_EXTRACT_FILENAME|chase_flags, ret_filename, &pfd); if (r < 0) return r; return pfd; }