| /* SPDX-License-Identifier: LGPL-2.1+ */ |
| |
| #include <errno.h> |
| #include <stddef.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <sys/stat.h> |
| #include <linux/magic.h> |
| #include <time.h> |
| #include <unistd.h> |
| |
| #include "alloc-util.h" |
| #include "dirent-util.h" |
| #include "fd-util.h" |
| #include "fs-util.h" |
| #include "locale-util.h" |
| #include "log.h" |
| #include "macro.h" |
| #include "missing.h" |
| #include "mkdir.h" |
| #include "parse-util.h" |
| #include "path-util.h" |
| #include "process-util.h" |
| #include "stat-util.h" |
| #include "stdio-util.h" |
| #include "string-util.h" |
| #include "strv.h" |
| #include "time-util.h" |
| #include "tmpfile-util.h" |
| #include "user-util.h" |
| #include "util.h" |
| |
| int unlink_noerrno(const char *path) { |
| PROTECT_ERRNO; |
| int r; |
| |
| r = unlink(path); |
| if (r < 0) |
| return -errno; |
| |
| return 0; |
| } |
| |
| int rmdir_parents(const char *path, const char *stop) { |
| size_t l; |
| int r = 0; |
| |
| assert(path); |
| assert(stop); |
| |
| l = strlen(path); |
| |
| /* Skip trailing slashes */ |
| while (l > 0 && path[l-1] == '/') |
| l--; |
| |
| while (l > 0) { |
| char *t; |
| |
| /* Skip last component */ |
| while (l > 0 && path[l-1] != '/') |
| l--; |
| |
| /* Skip trailing slashes */ |
| while (l > 0 && path[l-1] == '/') |
| l--; |
| |
| if (l <= 0) |
| break; |
| |
| t = strndup(path, l); |
| if (!t) |
| return -ENOMEM; |
| |
| if (path_startswith(stop, t)) { |
| free(t); |
| return 0; |
| } |
| |
| r = rmdir(t); |
| free(t); |
| |
| if (r < 0) |
| if (errno != ENOENT) |
| return -errno; |
| } |
| |
| return 0; |
| } |
| |
| int rename_noreplace(int olddirfd, const char *oldpath, int newdirfd, const char *newpath) { |
| int r; |
| |
| /* Try the ideal approach first */ |
| if (renameat2(olddirfd, oldpath, newdirfd, newpath, RENAME_NOREPLACE) >= 0) |
| return 0; |
| |
| /* renameat2() exists since Linux 3.15, btrfs and FAT added support for it later. If it is not implemented, |
| * fall back to a different method. */ |
| if (!IN_SET(errno, EINVAL, ENOSYS, ENOTTY)) |
| return -errno; |
| |
| /* Let's try to use linkat()+unlinkat() as fallback. This doesn't work on directories and on some file systems |
| * that do not support hard links (such as FAT, most prominently), but for files it's pretty close to what we |
| * want â though not atomic (i.e. for a short period both the new and the old filename will exist). */ |
| if (linkat(olddirfd, oldpath, newdirfd, newpath, 0) >= 0) { |
| |
| if (unlinkat(olddirfd, oldpath, 0) < 0) { |
| r = -errno; /* Backup errno before the following unlinkat() alters it */ |
| (void) unlinkat(newdirfd, newpath, 0); |
| return r; |
| } |
| |
| return 0; |
| } |
| |
| if (!IN_SET(errno, EINVAL, ENOSYS, ENOTTY, EPERM)) /* FAT returns EPERM on link()âĻ */ |
| return -errno; |
| |
| /* OK, neither RENAME_NOREPLACE nor linkat()+unlinkat() worked. Let's then fallback to the racy TOCTOU |
| * vulnerable accessat(F_OK) check followed by classic, replacing renameat(), we have nothing better. */ |
| |
| if (faccessat(newdirfd, newpath, F_OK, AT_SYMLINK_NOFOLLOW) >= 0) |
| return -EEXIST; |
| if (errno != ENOENT) |
| return -errno; |
| |
| if (renameat(olddirfd, oldpath, newdirfd, newpath) < 0) |
| return -errno; |
| |
| return 0; |
| } |
| |
| int readlinkat_malloc(int fd, const char *p, char **ret) { |
| size_t l = FILENAME_MAX+1; |
| int r; |
| |
| assert(p); |
| assert(ret); |
| |
| for (;;) { |
| char *c; |
| ssize_t n; |
| |
| c = new(char, l); |
| if (!c) |
| return -ENOMEM; |
| |
| n = readlinkat(fd, p, c, l-1); |
| if (n < 0) { |
| r = -errno; |
| free(c); |
| return r; |
| } |
| |
| if ((size_t) n < l-1) { |
| c[n] = 0; |
| *ret = c; |
| return 0; |
| } |
| |
| free(c); |
| l *= 2; |
| } |
| } |
| |
| int readlink_malloc(const char *p, char **ret) { |
| return readlinkat_malloc(AT_FDCWD, p, ret); |
| } |
| |
| int readlink_value(const char *p, char **ret) { |
| _cleanup_free_ char *link = NULL; |
| char *value; |
| int r; |
| |
| r = readlink_malloc(p, &link); |
| if (r < 0) |
| return r; |
| |
| value = basename(link); |
| if (!value) |
| return -ENOENT; |
| |
| value = strdup(value); |
| if (!value) |
| return -ENOMEM; |
| |
| *ret = value; |
| |
| return 0; |
| } |
| |
| int readlink_and_make_absolute(const char *p, char **r) { |
| _cleanup_free_ char *target = NULL; |
| char *k; |
| int j; |
| |
| assert(p); |
| assert(r); |
| |
| j = readlink_malloc(p, &target); |
| if (j < 0) |
| return j; |
| |
| k = file_in_same_dir(p, target); |
| if (!k) |
| return -ENOMEM; |
| |
| *r = k; |
| return 0; |
| } |
| |
| int chmod_and_chown(const char *path, mode_t mode, uid_t uid, gid_t gid) { |
| char fd_path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int) + 1]; |
| _cleanup_close_ int fd = -1; |
| assert(path); |
| |
| /* Under the assumption that we are running privileged we first change the access mode and only then hand out |
| * ownership to avoid a window where access is too open. */ |
| |
| fd = open(path, O_PATH|O_CLOEXEC|O_NOFOLLOW); /* Let's acquire an O_PATH fd, as precaution to change mode/owner |
| * on the same file */ |
| if (fd < 0) |
| return -errno; |
| |
| xsprintf(fd_path, "/proc/self/fd/%i", fd); |
| |
| if (mode != MODE_INVALID) { |
| |
| if ((mode & S_IFMT) != 0) { |
| struct stat st; |
| |
| if (stat(fd_path, &st) < 0) |
| return -errno; |
| |
| if ((mode & S_IFMT) != (st.st_mode & S_IFMT)) |
| return -EINVAL; |
| } |
| |
| if (chmod(fd_path, mode & 07777) < 0) |
| return -errno; |
| } |
| |
| if (uid != UID_INVALID || gid != GID_INVALID) |
| if (chown(fd_path, uid, gid) < 0) |
| return -errno; |
| |
| return 0; |
| } |
| |
| int fchmod_and_chown(int fd, mode_t mode, uid_t uid, gid_t gid) { |
| /* Under the assumption that we are running privileged we first change the access mode and only then hand out |
| * ownership to avoid a window where access is too open. */ |
| |
| if (mode != MODE_INVALID) { |
| |
| if ((mode & S_IFMT) != 0) { |
| struct stat st; |
| |
| if (fstat(fd, &st) < 0) |
| return -errno; |
| |
| if ((mode & S_IFMT) != (st.st_mode & S_IFMT)) |
| return -EINVAL; |
| } |
| |
| if (fchmod(fd, mode & 0777) < 0) |
| return -errno; |
| } |
| |
| if (uid != UID_INVALID || gid != GID_INVALID) |
| if (fchown(fd, uid, gid) < 0) |
| return -errno; |
| |
| return 0; |
| } |
| |
| int fchmod_umask(int fd, mode_t m) { |
| mode_t u; |
| int r; |
| |
| u = umask(0777); |
| r = fchmod(fd, m & (~u)) < 0 ? -errno : 0; |
| umask(u); |
| |
| return r; |
| } |
| |
| int fchmod_opath(int fd, mode_t m) { |
| char procfs_path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int)]; |
| |
| /* This function operates also on fd that might have been opened with |
| * O_PATH. Indeed fchmodat() doesn't have the AT_EMPTY_PATH flag like |
| * fchownat() does. */ |
| |
| xsprintf(procfs_path, "/proc/self/fd/%i", fd); |
| if (chmod(procfs_path, m) < 0) |
| return -errno; |
| |
| return 0; |
| } |
| |
| int fd_warn_permissions(const char *path, int fd) { |
| struct stat st; |
| |
| if (fstat(fd, &st) < 0) |
| return -errno; |
| |
| if (st.st_mode & 0111) |
| log_warning("Configuration file %s is marked executable. Please remove executable permission bits. Proceeding anyway.", path); |
| |
| if (st.st_mode & 0002) |
| log_warning("Configuration file %s is marked world-writable. Please remove world writability permission bits. Proceeding anyway.", path); |
| |
| if (getpid_cached() == 1 && (st.st_mode & 0044) != 0044) |
| log_warning("Configuration file %s is marked world-inaccessible. This has no effect as configuration data is accessible via APIs without restrictions. Proceeding anyway.", path); |
| |
| return 0; |
| } |
| |
| int touch_file(const char *path, bool parents, usec_t stamp, uid_t uid, gid_t gid, mode_t mode) { |
| char fdpath[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int)]; |
| _cleanup_close_ int fd = -1; |
| int r, ret = 0; |
| |
| assert(path); |
| |
| /* Note that touch_file() does not follow symlinks: if invoked on an existing symlink, then it is the symlink |
| * itself which is updated, not its target |
| * |
| * Returns the first error we encounter, but tries to apply as much as possible. */ |
| |
| if (parents) |
| (void) mkdir_parents(path, 0755); |
| |
| /* Initially, we try to open the node with O_PATH, so that we get a reference to the node. This is useful in |
| * case the path refers to an existing device or socket node, as we can open it successfully in all cases, and |
| * won't trigger any driver magic or so. */ |
| fd = open(path, O_PATH|O_CLOEXEC|O_NOFOLLOW); |
| if (fd < 0) { |
| if (errno != ENOENT) |
| return -errno; |
| |
| /* if the node doesn't exist yet, we create it, but with O_EXCL, so that we only create a regular file |
| * here, and nothing else */ |
| fd = open(path, O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, IN_SET(mode, 0, MODE_INVALID) ? 0644 : mode); |
| if (fd < 0) |
| return -errno; |
| } |
| |
| /* Let's make a path from the fd, and operate on that. With this logic, we can adjust the access mode, |
| * ownership and time of the file node in all cases, even if the fd refers to an O_PATH object â which is |
| * something fchown(), fchmod(), futimensat() don't allow. */ |
| xsprintf(fdpath, "/proc/self/fd/%i", fd); |
| |
| if (mode != MODE_INVALID) |
| if (chmod(fdpath, mode) < 0) |
| ret = -errno; |
| |
| if (uid_is_valid(uid) || gid_is_valid(gid)) |
| if (chown(fdpath, uid, gid) < 0 && ret >= 0) |
| ret = -errno; |
| |
| if (stamp != USEC_INFINITY) { |
| struct timespec ts[2]; |
| |
| timespec_store(&ts[0], stamp); |
| ts[1] = ts[0]; |
| r = utimensat(AT_FDCWD, fdpath, ts, 0); |
| } else |
| r = utimensat(AT_FDCWD, fdpath, NULL, 0); |
| if (r < 0 && ret >= 0) |
| return -errno; |
| |
| return ret; |
| } |
| |
| int touch(const char *path) { |
| return touch_file(path, false, USEC_INFINITY, UID_INVALID, GID_INVALID, MODE_INVALID); |
| } |
| |
| int symlink_idempotent(const char *from, const char *to, bool make_relative) { |
| _cleanup_free_ char *relpath = NULL; |
| int r; |
| |
| assert(from); |
| assert(to); |
| |
| if (make_relative) { |
| _cleanup_free_ char *parent = NULL; |
| |
| parent = dirname_malloc(to); |
| if (!parent) |
| return -ENOMEM; |
| |
| r = path_make_relative(parent, from, &relpath); |
| if (r < 0) |
| return r; |
| |
| from = relpath; |
| } |
| |
| if (symlink(from, to) < 0) { |
| _cleanup_free_ char *p = NULL; |
| |
| if (errno != EEXIST) |
| return -errno; |
| |
| r = readlink_malloc(to, &p); |
| if (r == -EINVAL) /* Not a symlink? In that case return the original error we encountered: -EEXIST */ |
| return -EEXIST; |
| if (r < 0) /* Any other error? In that case propagate it as is */ |
| return r; |
| |
| if (!streq(p, from)) /* Not the symlink we want it to be? In that case, propagate the original -EEXIST */ |
| return -EEXIST; |
| } |
| |
| return 0; |
| } |
| |
| int symlink_atomic(const char *from, const char *to) { |
| _cleanup_free_ char *t = NULL; |
| int r; |
| |
| assert(from); |
| assert(to); |
| |
| r = tempfn_random(to, NULL, &t); |
| if (r < 0) |
| return r; |
| |
| if (symlink(from, t) < 0) |
| return -errno; |
| |
| if (rename(t, to) < 0) { |
| unlink_noerrno(t); |
| return -errno; |
| } |
| |
| return 0; |
| } |
| |
| int mknod_atomic(const char *path, mode_t mode, dev_t dev) { |
| _cleanup_free_ char *t = NULL; |
| int r; |
| |
| assert(path); |
| |
| r = tempfn_random(path, NULL, &t); |
| if (r < 0) |
| return r; |
| |
| if (mknod(t, mode, dev) < 0) |
| return -errno; |
| |
| if (rename(t, path) < 0) { |
| unlink_noerrno(t); |
| return -errno; |
| } |
| |
| return 0; |
| } |
| |
| int mkfifo_atomic(const char *path, mode_t mode) { |
| _cleanup_free_ char *t = NULL; |
| int r; |
| |
| assert(path); |
| |
| r = tempfn_random(path, NULL, &t); |
| if (r < 0) |
| return r; |
| |
| if (mkfifo(t, mode) < 0) |
| return -errno; |
| |
| if (rename(t, path) < 0) { |
| unlink_noerrno(t); |
| return -errno; |
| } |
| |
| return 0; |
| } |
| |
| int mkfifoat_atomic(int dirfd, const char *path, mode_t mode) { |
| _cleanup_free_ char *t = NULL; |
| int r; |
| |
| assert(path); |
| |
| if (path_is_absolute(path)) |
| return mkfifo_atomic(path, mode); |
| |
| /* We're only interested in the (random) filename. */ |
| r = tempfn_random_child("", NULL, &t); |
| if (r < 0) |
| return r; |
| |
| if (mkfifoat(dirfd, t, mode) < 0) |
| return -errno; |
| |
| if (renameat(dirfd, t, dirfd, path) < 0) { |
| unlink_noerrno(t); |
| return -errno; |
| } |
| |
| return 0; |
| } |
| |
| int get_files_in_directory(const char *path, char ***list) { |
| _cleanup_closedir_ DIR *d = NULL; |
| struct dirent *de; |
| size_t bufsize = 0, n = 0; |
| _cleanup_strv_free_ char **l = NULL; |
| |
| assert(path); |
| |
| /* Returns all files in a directory in *list, and the number |
| * of files as return value. If list is NULL returns only the |
| * number. */ |
| |
| d = opendir(path); |
| if (!d) |
| return -errno; |
| |
| FOREACH_DIRENT_ALL(de, d, return -errno) { |
| dirent_ensure_type(d, de); |
| |
| if (!dirent_is_file(de)) |
| continue; |
| |
| if (list) { |
| /* one extra slot is needed for the terminating NULL */ |
| if (!GREEDY_REALLOC(l, bufsize, n + 2)) |
| return -ENOMEM; |
| |
| l[n] = strdup(de->d_name); |
| if (!l[n]) |
| return -ENOMEM; |
| |
| l[++n] = NULL; |
| } else |
| n++; |
| } |
| |
| if (list) |
| *list = TAKE_PTR(l); |
| |
| return n; |
| } |
| |
| static int getenv_tmp_dir(const char **ret_path) { |
| const char *n; |
| int r, ret = 0; |
| |
| assert(ret_path); |
| |
| /* We use the same order of environment variables python uses in tempfile.gettempdir(): |
| * https://docs.python.org/3/library/tempfile.html#tempfile.gettempdir */ |
| FOREACH_STRING(n, "TMPDIR", "TEMP", "TMP") { |
| const char *e; |
| |
| e = secure_getenv(n); |
| if (!e) |
| continue; |
| if (!path_is_absolute(e)) { |
| r = -ENOTDIR; |
| goto next; |
| } |
| if (!path_is_normalized(e)) { |
| r = -EPERM; |
| goto next; |
| } |
| |
| r = is_dir(e, true); |
| if (r < 0) |
| goto next; |
| if (r == 0) { |
| r = -ENOTDIR; |
| goto next; |
| } |
| |
| *ret_path = e; |
| return 1; |
| |
| next: |
| /* Remember first error, to make this more debuggable */ |
| if (ret >= 0) |
| ret = r; |
| } |
| |
| if (ret < 0) |
| return ret; |
| |
| *ret_path = NULL; |
| return ret; |
| } |
| |
| static int tmp_dir_internal(const char *def, const char **ret) { |
| const char *e; |
| int r, k; |
| |
| assert(def); |
| assert(ret); |
| |
| r = getenv_tmp_dir(&e); |
| if (r > 0) { |
| *ret = e; |
| return 0; |
| } |
| |
| k = is_dir(def, true); |
| if (k == 0) |
| k = -ENOTDIR; |
| if (k < 0) |
| return r < 0 ? r : k; |
| |
| *ret = def; |
| return 0; |
| } |
| |
| int var_tmp_dir(const char **ret) { |
| |
| /* Returns the location for "larger" temporary files, that is backed by physical storage if available, and thus |
| * even might survive a boot: /var/tmp. If $TMPDIR (or related environment variables) are set, its value is |
| * returned preferably however. Note that both this function and tmp_dir() below are affected by $TMPDIR, |
| * making it a variable that overrides all temporary file storage locations. */ |
| |
| return tmp_dir_internal("/var/tmp", ret); |
| } |
| |
| int tmp_dir(const char **ret) { |
| |
| /* Similar to var_tmp_dir() above, but returns the location for "smaller" temporary files, which is usually |
| * backed by an in-memory file system: /tmp. */ |
| |
| return tmp_dir_internal("/tmp", ret); |
| } |
| |
| int unlink_or_warn(const char *filename) { |
| if (unlink(filename) < 0 && errno != ENOENT) |
| /* If the file doesn't exist and the fs simply was read-only (in which |
| * case unlink() returns EROFS even if the file doesn't exist), don't |
| * complain */ |
| if (errno != EROFS || access(filename, F_OK) >= 0) |
| return log_error_errno(errno, "Failed to remove \"%s\": %m", filename); |
| |
| return 0; |
| } |
| |
| int inotify_add_watch_fd(int fd, int what, uint32_t mask) { |
| char path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int) + 1]; |
| int r; |
| |
| /* This is like inotify_add_watch(), except that the file to watch is not referenced by a path, but by an fd */ |
| xsprintf(path, "/proc/self/fd/%i", what); |
| |
| r = inotify_add_watch(fd, path, mask); |
| if (r < 0) |
| return -errno; |
| |
| return r; |
| } |
| |
| static 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, unsigned flags) { |
| _cleanup_free_ char *n1 = NULL, *n2 = NULL; |
| |
| if (!FLAGS_SET(flags, CHASE_WARN)) |
| return -ENOLINK; |
| |
| (void) fd_get_path(a, &n1); |
| (void) fd_get_path(b, &n2); |
| |
| return log_warning_errno(SYNTHETIC_ERRNO(ENOLINK), |
| "Detected unsafe path transition %s %s %s during canonicalization of %s.", |
| n1, special_glyph(SPECIAL_GLYPH_ARROW), n2, path); |
| } |
| |
| static int log_autofs_mount_point(int fd, const char *path, unsigned 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.", |
| n1, path); |
| } |
| |
| int chase_symlinks(const char *path, const char *original_root, unsigned flags, char **ret) { |
| _cleanup_free_ char *buffer = NULL, *done = NULL, *root = NULL; |
| _cleanup_close_ int fd = -1; |
| unsigned max_follow = CHASE_SYMLINKS_MAX; /* how many symlinks to follow before giving up and returning ELOOP */ |
| struct stat previous_stat; |
| bool exists = true; |
| char *todo; |
| int r; |
| |
| assert(path); |
| |
| /* 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 | CHASE_OPEN)) |
| return -EINVAL; |
| |
| if (FLAGS_SET(flags, CHASE_STEP | CHASE_OPEN)) |
| return -EINVAL; |
| |
| if (isempty(path)) |
| return -EINVAL; |
| |
| /* This is a lot like canonicalize_file_name(), but takes an additional "root" parameter, that allows following |
| * symlinks relative to a root directory, instead of the root of the host. |
| * |
| * Note that "root" primarily matters if we encounter an absolute symlink. It is also used when following |
| * relative symlinks to ensure they cannot be used to "escape" the root directory. The path parameter passed is |
| * assumed to be already prefixed by it, except if the CHASE_PREFIX_ROOT flag is set, in which case it is first |
| * prefixed accordingly. |
| * |
| * 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 it's special meaning |
| * each time. The "todo" path always starts with at least one slash, the "done" path always ends in no |
| * slash. We always keep an O_PATH fd to the component we are currently processing, thus keeping lookup races |
| * at 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 root parameter to tell this |
| * function what to do when encountering a symlink with an absolute path as directory: prefix it by the |
| * specified path. |
| * |
| * There are three ways to invoke this function: |
| * |
| * 1. Without CHASE_STEP or CHASE_OPEN: in this case the path is resolved and the normalized path is returned |
| * in `ret`. 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 doesn't. |
| * |
| * 2. With CHASE_OPEN: 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. CHASE_OPEN 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 a 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. |
| * |
| * 5. With CHASE_NO_AUTOFS: in this case if an autofs mount point is encountered, the 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. |
| * |
| * */ |
| |
| /* A root directory of "/" or "" is identical to none */ |
| if (empty_or_root(original_root)) |
| original_root = NULL; |
| |
| if (!original_root && !ret && (flags & (CHASE_NONEXISTENT|CHASE_NO_AUTOFS|CHASE_SAFE|CHASE_OPEN|CHASE_STEP)) == CHASE_OPEN) { |
| /* Shortcut the CHASE_OPEN 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 = open(path, O_PATH|O_CLOEXEC|((flags & CHASE_NOFOLLOW) ? O_NOFOLLOW : 0)); |
| if (r < 0) |
| return -errno; |
| |
| return r; |
| } |
| |
| if (original_root) { |
| r = path_make_absolute_cwd(original_root, &root); |
| if (r < 0) |
| return r; |
| |
| if (flags & CHASE_PREFIX_ROOT) { |
| |
| /* We don't support relative paths in combination with a root directory */ |
| if (!path_is_absolute(path)) |
| return -EINVAL; |
| |
| path = prefix_roota(root, path); |
| } |
| } |
| |
| r = path_make_absolute_cwd(path, &buffer); |
| if (r < 0) |
| return r; |
| |
| fd = open("/", O_CLOEXEC|O_NOFOLLOW|O_PATH); |
| if (fd < 0) |
| return -errno; |
| |
| if (flags & CHASE_SAFE) { |
| if (fstat(fd, &previous_stat) < 0) |
| return -errno; |
| } |
| |
| todo = buffer; |
| for (;;) { |
| _cleanup_free_ char *first = NULL; |
| _cleanup_close_ int child = -1; |
| struct stat st; |
| size_t n, m; |
| |
| /* Determine length of first component in the path */ |
| n = strspn(todo, "/"); /* The slashes */ |
| m = n + strcspn(todo + n, "/"); /* The entire length of the component */ |
| |
| /* Extract the first component. */ |
| first = strndup(todo, m); |
| if (!first) |
| return -ENOMEM; |
| |
| todo += m; |
| |
| /* Empty? Then we reached the end. */ |
| if (isempty(first)) |
| break; |
| |
| /* Just a single slash? Then we reached the end. */ |
| if (path_equal(first, "/")) { |
| /* Preserve the trailing slash */ |
| |
| if (flags & CHASE_TRAIL_SLASH) |
| if (!strextend(&done, "/", NULL)) |
| return -ENOMEM; |
| |
| break; |
| } |
| |
| /* Just a dot? Then let's eat this up. */ |
| if (path_equal(first, "/.")) |
| continue; |
| |
| /* 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 = -1; |
| |
| /* 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)) |
| continue; |
| |
| parent = dirname_malloc(done); |
| if (!parent) |
| return -ENOMEM; |
| |
| /* Don't allow this to leave the root dir. */ |
| if (root && |
| path_startswith(done, root) && |
| !path_startswith(parent, root)) |
| continue; |
| |
| free_and_replace(done, parent); |
| |
| if (flags & CHASE_STEP) |
| goto chased_one; |
| |
| fd_parent = openat(fd, "..", O_CLOEXEC|O_NOFOLLOW|O_PATH); |
| if (fd_parent < 0) |
| return -errno; |
| |
| if (flags & CHASE_SAFE) { |
| if (fstat(fd_parent, &st) < 0) |
| return -errno; |
| |
| if (unsafe_transition(&previous_stat, &st)) |
| return log_unsafe_transition(fd, fd_parent, path, flags); |
| |
| previous_stat = st; |
| } |
| |
| safe_close(fd); |
| fd = TAKE_FD(fd_parent); |
| |
| continue; |
| } |
| |
| /* Otherwise let's see what this is. */ |
| child = openat(fd, first + n, O_CLOEXEC|O_NOFOLLOW|O_PATH); |
| if (child < 0) { |
| |
| if (errno == ENOENT && |
| (flags & CHASE_NONEXISTENT) && |
| (isempty(todo) || path_is_normalized(todo))) { |
| |
| /* If CHASE_NONEXISTENT is set, and the path does not exist, then that's OK, return |
| * what we got so far. But don't allow this if the remaining path contains "../ or "./" |
| * or something else weird. */ |
| |
| /* If done is "/", as first also contains slash at the head, then remove this redundant slash. */ |
| if (streq_ptr(done, "/")) |
| *done = '\0'; |
| |
| if (!strextend(&done, first, todo, NULL)) |
| return -ENOMEM; |
| |
| exists = false; |
| break; |
| } |
| |
| return -errno; |
| } |
| |
| if (fstat(child, &st) < 0) |
| return -errno; |
| if ((flags & CHASE_SAFE) && |
| unsafe_transition(&previous_stat, &st)) |
| return log_unsafe_transition(fd, child, path, flags); |
| |
| previous_stat = st; |
| |
| if ((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.st_mode) && !((flags & CHASE_NOFOLLOW) && isempty(todo))) { |
| char *joined; |
| |
| _cleanup_free_ char *destination = NULL; |
| |
| /* 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 + n, &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 |
| * directory as base. */ |
| |
| safe_close(fd); |
| fd = open(root ?: "/", O_CLOEXEC|O_NOFOLLOW|O_PATH); |
| if (fd < 0) |
| return -errno; |
| |
| if (flags & CHASE_SAFE) { |
| if (fstat(fd, &st) < 0) |
| return -errno; |
| |
| if (unsafe_transition(&previous_stat, &st)) |
| return log_unsafe_transition(child, fd, path, flags); |
| |
| previous_stat = st; |
| } |
| |
| free(done); |
| |
| /* Note that we do not revalidate the root, we take it as is. */ |
| if (isempty(root)) |
| done = NULL; |
| else { |
| done = strdup(root); |
| if (!done) |
| return -ENOMEM; |
| } |
| |
| /* Prefix what's left to do with what we just read, and start the loop again, but |
| * remain in the current directory. */ |
| joined = strjoin(destination, todo); |
| } else |
| joined = strjoin("/", destination, todo); |
| if (!joined) |
| return -ENOMEM; |
| |
| free(buffer); |
| todo = buffer = joined; |
| |
| if (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 (!done) |
| done = TAKE_PTR(first); |
| else { |
| /* If done is "/", as first also contains slash at the head, then remove this redundant slash. */ |
| if (streq(done, "/")) |
| *done = '\0'; |
| |
| if (!strextend(&done, first, NULL)) |
| return -ENOMEM; |
| } |
| |
| /* And iterate again, but go one directory further down. */ |
| safe_close(fd); |
| fd = TAKE_FD(child); |
| } |
| |
| if (!done) { |
| /* Special case, turn the empty string into "/", to indicate the root directory. */ |
| done = strdup("/"); |
| if (!done) |
| return -ENOMEM; |
| } |
| |
| if (ret) |
| *ret = TAKE_PTR(done); |
| |
| if (flags & CHASE_OPEN) { |
| /* 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); |
| return TAKE_FD(fd); |
| } |
| |
| if (flags & CHASE_STEP) |
| return 1; |
| |
| return exists; |
| |
| chased_one: |
| if (ret) { |
| char *c; |
| |
| c = strjoin(strempty(done), todo); |
| if (!c) |
| return -ENOMEM; |
| |
| *ret = c; |
| } |
| |
| return 0; |
| } |
| |
| int chase_symlinks_and_open( |
| const char *path, |
| const char *root, |
| unsigned chase_flags, |
| int open_flags, |
| char **ret_path) { |
| |
| _cleanup_close_ int path_fd = -1; |
| _cleanup_free_ char *p = NULL; |
| int r; |
| |
| if (chase_flags & CHASE_NONEXISTENT) |
| return -EINVAL; |
| |
| if (empty_or_root(root) && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE)) == 0) { |
| /* Shortcut this call if none of the special features of this call are requested */ |
| r = open(path, open_flags); |
| if (r < 0) |
| return -errno; |
| |
| return r; |
| } |
| |
| path_fd = chase_symlinks(path, root, chase_flags|CHASE_OPEN, ret_path ? &p : NULL); |
| if (path_fd < 0) |
| return path_fd; |
| |
| r = fd_reopen(path_fd, open_flags); |
| if (r < 0) |
| return r; |
| |
| if (ret_path) |
| *ret_path = TAKE_PTR(p); |
| |
| return r; |
| } |
| |
| int chase_symlinks_and_opendir( |
| const char *path, |
| const char *root, |
| unsigned chase_flags, |
| char **ret_path, |
| DIR **ret_dir) { |
| |
| char procfs_path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int)]; |
| _cleanup_close_ int path_fd = -1; |
| _cleanup_free_ char *p = NULL; |
| DIR *d; |
| |
| if (!ret_dir) |
| return -EINVAL; |
| if (chase_flags & CHASE_NONEXISTENT) |
| return -EINVAL; |
| |
| if (empty_or_root(root) && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE)) == 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; |
| } |
| |
| path_fd = chase_symlinks(path, root, chase_flags|CHASE_OPEN, ret_path ? &p : NULL); |
| if (path_fd < 0) |
| return path_fd; |
| |
| xsprintf(procfs_path, "/proc/self/fd/%i", path_fd); |
| d = opendir(procfs_path); |
| if (!d) |
| return -errno; |
| |
| if (ret_path) |
| *ret_path = TAKE_PTR(p); |
| |
| *ret_dir = d; |
| return 0; |
| } |
| |
| int chase_symlinks_and_stat( |
| const char *path, |
| const char *root, |
| unsigned chase_flags, |
| char **ret_path, |
| struct stat *ret_stat) { |
| |
| _cleanup_close_ int path_fd = -1; |
| _cleanup_free_ char *p = NULL; |
| |
| assert(path); |
| assert(ret_stat); |
| |
| if (chase_flags & CHASE_NONEXISTENT) |
| return -EINVAL; |
| |
| if (empty_or_root(root) && !ret_path && (chase_flags & (CHASE_NO_AUTOFS|CHASE_SAFE)) == 0) { |
| /* Shortcut this call if none of the special features of this call are requested */ |
| if (stat(path, ret_stat) < 0) |
| return -errno; |
| |
| return 1; |
| } |
| |
| path_fd = chase_symlinks(path, root, chase_flags|CHASE_OPEN, ret_path ? &p : NULL); |
| if (path_fd < 0) |
| return path_fd; |
| |
| if (fstat(path_fd, ret_stat) < 0) |
| return -errno; |
| |
| if (ret_path) |
| *ret_path = TAKE_PTR(p); |
| |
| if (chase_flags & CHASE_OPEN) |
| return TAKE_FD(path_fd); |
| |
| return 1; |
| } |
| |
| int access_fd(int fd, int mode) { |
| char p[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(fd) + 1]; |
| int r; |
| |
| /* Like access() but operates on an already open fd */ |
| |
| xsprintf(p, "/proc/self/fd/%i", fd); |
| r = access(p, mode); |
| if (r < 0) |
| return -errno; |
| |
| return r; |
| } |
| |
| void unlink_tempfilep(char (*p)[]) { |
| /* If the file is created with mkstemp(), it will (almost always) |
| * change the suffix. Treat this as a sign that the file was |
| * successfully created. We ignore both the rare case where the |
| * original suffix is used and unlink failures. */ |
| if (!endswith(*p, ".XXXXXX")) |
| (void) unlink_noerrno(*p); |
| } |
| |
| int unlinkat_deallocate(int fd, const char *name, int flags) { |
| _cleanup_close_ int truncate_fd = -1; |
| struct stat st; |
| off_t l, bs; |
| |
| /* Operates like unlinkat() but also deallocates the file contents if it is a regular file and there's no other |
| * link to it. This is useful to ensure that other processes that might have the file open for reading won't be |
| * able to keep the data pinned on disk forever. This call is particular useful whenever we execute clean-up |
| * jobs ("vacuuming"), where we want to make sure the data is really gone and the disk space released and |
| * returned to the free pool. |
| * |
| * Deallocation is preferably done by FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE (đ) if supported, which means |
| * the file won't change size. That's a good thing since we shouldn't needlessly trigger SIGBUS in other |
| * programs that have mmap()ed the file. (The assumption here is that changing file contents to all zeroes |
| * underneath those programs is the better choice than simply triggering SIGBUS in them which truncation does.) |
| * However if hole punching is not implemented in the kernel or file system we'll fall back to normal file |
| * truncation (đĒ), as our goal of deallocating the data space trumps our goal of being nice to readers (đ). |
| * |
| * Note that we attempt deallocation, but failure to succeed with that is not considered fatal, as long as the |
| * primary job â to delete the file â is accomplished. */ |
| |
| if ((flags & AT_REMOVEDIR) == 0) { |
| truncate_fd = openat(fd, name, O_WRONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW|O_NONBLOCK); |
| if (truncate_fd < 0) { |
| |
| /* If this failed because the file doesn't exist propagate the error right-away. Also, |
| * AT_REMOVEDIR wasn't set, and we tried to open the file for writing, which means EISDIR is |
| * returned when this is a directory but we are not supposed to delete those, hence propagate |
| * the error right-away too. */ |
| if (IN_SET(errno, ENOENT, EISDIR)) |
| return -errno; |
| |
| if (errno != ELOOP) /* don't complain if this is a symlink */ |
| log_debug_errno(errno, "Failed to open file '%s' for deallocation, ignoring: %m", name); |
| } |
| } |
| |
| if (unlinkat(fd, name, flags) < 0) |
| return -errno; |
| |
| if (truncate_fd < 0) /* Don't have a file handle, can't do more âšī¸ */ |
| return 0; |
| |
| if (fstat(truncate_fd, &st) < 0) { |
| log_debug_errno(errno, "Failed to stat file '%s' for deallocation, ignoring: %m", name); |
| return 0; |
| } |
| |
| if (!S_ISREG(st.st_mode) || st.st_blocks == 0 || st.st_nlink > 0) |
| return 0; |
| |
| /* If this is a regular file, it actually took up space on disk and there are no other links it's time to |
| * punch-hole/truncate this to release the disk space. */ |
| |
| bs = MAX(st.st_blksize, 512); |
| l = DIV_ROUND_UP(st.st_size, bs) * bs; /* Round up to next block size */ |
| |
| if (fallocate(truncate_fd, FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE, 0, l) >= 0) |
| return 0; /* Successfully punched a hole! đ */ |
| |
| /* Fall back to truncation */ |
| if (ftruncate(truncate_fd, 0) < 0) { |
| log_debug_errno(errno, "Failed to truncate file to 0, ignoring: %m"); |
| return 0; |
| } |
| |
| return 0; |
| } |
| |
| int fsync_directory_of_file(int fd) { |
| _cleanup_free_ char *path = NULL; |
| _cleanup_close_ int dfd = -1; |
| int r; |
| |
| r = fd_verify_regular(fd); |
| if (r < 0) |
| return r; |
| |
| r = fd_get_path(fd, &path); |
| if (r < 0) { |
| log_debug_errno(r, "Failed to query /proc/self/fd/%d%s: %m", |
| fd, |
| r == -EOPNOTSUPP ? ", ignoring" : ""); |
| |
| if (r == -EOPNOTSUPP) |
| /* If /proc is not available, we're most likely running in some |
| * chroot environment, and syncing the directory is not very |
| * important in that case. Let's just silently do nothing. */ |
| return 0; |
| |
| return r; |
| } |
| |
| if (!path_is_absolute(path)) |
| return -EINVAL; |
| |
| dfd = open_parent(path, O_CLOEXEC, 0); |
| if (dfd < 0) |
| return dfd; |
| |
| if (fsync(dfd) < 0) |
| return -errno; |
| |
| return 0; |
| } |
| |
| int fsync_path_at(int at_fd, const char *path) { |
| _cleanup_close_ int opened_fd = -1; |
| int fd; |
| |
| if (isempty(path)) { |
| if (at_fd == AT_FDCWD) { |
| opened_fd = open(".", O_RDONLY|O_DIRECTORY|O_CLOEXEC); |
| if (opened_fd < 0) |
| return -errno; |
| |
| fd = opened_fd; |
| } else |
| fd = at_fd; |
| } else { |
| |
| opened_fd = openat(at_fd, path, O_RDONLY|O_CLOEXEC); |
| if (opened_fd < 0) |
| return -errno; |
| |
| fd = opened_fd; |
| } |
| |
| if (fsync(fd) < 0) |
| return -errno; |
| |
| return 0; |
| } |
| |
| int open_parent(const char *path, int flags, mode_t mode) { |
| _cleanup_free_ char *parent = NULL; |
| int fd; |
| |
| if (isempty(path)) |
| return -EINVAL; |
| if (path_equal(path, "/")) /* requesting the parent of the root dir is fishy, let's prohibit that */ |
| return -EINVAL; |
| |
| parent = dirname_malloc(path); |
| if (!parent) |
| return -ENOMEM; |
| |
| /* Let's insist on O_DIRECTORY since the parent of a file or directory is a directory. Except if we open an |
| * O_TMPFILE file, because in that case we are actually create a regular file below the parent directory. */ |
| |
| if ((flags & O_PATH) == O_PATH) |
| flags |= O_DIRECTORY; |
| else if ((flags & O_TMPFILE) != O_TMPFILE) |
| flags |= O_DIRECTORY|O_RDONLY; |
| |
| fd = open(parent, flags, mode); |
| if (fd < 0) |
| return -errno; |
| |
| return fd; |
| } |