/* SPDX-License-Identifier: LGPL-2.1+ */
-/***
- This file is part of systemd.
-
- Copyright 2010 Lennart Poettering
-
- systemd is free software; you can redistribute it and/or modify it
- under the terms of the GNU Lesser General Public License as published by
- the Free Software Foundation; either version 2.1 of the License, or
- (at your option) any later version.
-
- systemd is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public License
- along with systemd; If not, see <http://www.gnu.org/licenses/>.
-***/
#include <errno.h>
#include <stddef.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"
}
#if 0 /// UNNEEDED by elogind
-int readlink_and_canonicalize(const char *p, const char *root, char **ret) {
- char *t, *s;
- int r;
-
- assert(p);
- assert(ret);
-
- r = readlink_and_make_absolute(p, &t);
- if (r < 0)
- return r;
-
- r = chase_symlinks(t, root, 0, &s);
- if (r < 0)
- /* If we can't follow up, then let's return the original string, slightly cleaned up. */
- *ret = path_kill_slashes(t);
- else {
- *ret = s;
- free(t);
- }
-
- return 0;
-}
-
-int readlink_and_make_absolute_root(const char *root, const char *path, char **ret) {
- _cleanup_free_ char *target = NULL, *t = NULL;
- const char *full;
- int r;
+#endif // 0
+int chmod_and_chown(const char *path, mode_t mode, uid_t uid, gid_t gid) {
+ assert(path);
- full = prefix_roota(root, path);
- r = readlink_malloc(full, &target);
- if (r < 0)
- return r;
+ /* 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. */
- t = file_in_same_dir(path, target);
- if (!t)
- return -ENOMEM;
+ if (mode != MODE_INVALID)
+ if (chmod(path, mode) < 0)
+ return -errno;
- *ret = t;
- t = NULL;
+ if (uid != UID_INVALID || gid != GID_INVALID)
+ if (chown(path, uid, gid) < 0)
+ return -errno;
return 0;
}
-#endif // 0
-
-int chmod_and_chown(const char *path, mode_t mode, uid_t uid, gid_t gid) {
- assert(path);
+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 (chmod(path, mode) < 0)
+ if (fchmod(fd, mode) < 0)
return -errno;
if (uid != UID_INVALID || gid != GID_INVALID)
- if (chown(path, uid, gid) < 0)
+ if (fchown(fd, uid, gid) < 0)
return -errno;
return 0;
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;
n++;
}
- if (list) {
- *list = l;
- l = NULL; /* avoid freeing */
- }
+ if (list)
+ *list = TAKE_PTR(l);
return n;
}
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;
+}
+
#if 0 /// UNNEEDED by elogind
int inotify_add_watch_fd(int fd, int what, uint32_t mask) {
char path[STRLEN("/proc/self/fd/") + DECIMAL_STR_MAX(int) + 1];
}
#endif // 0
+static bool safe_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 true;
+
+ return a->st_uid == b->st_uid; /* Otherwise we need to stay within the same UID */
+}
+
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 = 32; /* how many symlinks to follow before giving up and returning ELOOP */
+ 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.
*
* 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. */
+ * 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.
+ *
+ * */
+
+ /* 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);
+ 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)
+ 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 (fd < 0)
return -errno;
+ if (flags & CHASE_SAFE) {
+ if (fstat(fd, &previous_stat) < 0)
+ return -errno;
+ }
+
todo = buffer;
for (;;) {
_cleanup_free_ char *first = NULL;
/* Just a single slash? Then we reached the end. */
if (path_equal(first, "/")) {
/* Preserve the trailing slash */
- if (!strextend(&done, "/", NULL))
- return -ENOMEM;
+
+ if (flags & CHASE_TRAIL_SLASH)
+ if (!strextend(&done, "/", NULL))
+ return -ENOMEM;
break;
}
/* Two dots? Then chop off the last bit of what we already found out. */
if (path_equal(first, "/..")) {
_cleanup_free_ char *parent = NULL;
- int fd_parent = -1;
+ _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 (isempty(done) || path_equal(done, "/"))
+ if (empty_or_root(done))
continue;
parent = dirname_malloc(done);
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 (!safe_transition(&previous_stat, &st))
+ return -EPERM;
+
+ previous_stat = st;
+ }
+
safe_close(fd);
- fd = fd_parent;
+ fd = TAKE_FD(fd_parent);
continue;
}
if (fstat(child, &st) < 0)
return -errno;
+ if ((flags & CHASE_SAFE) &&
+ !safe_transition(&previous_stat, &st))
+ return -EPERM;
+
+ previous_stat = st;
+
if ((flags & CHASE_NO_AUTOFS) &&
fd_is_fs_type(child, AUTOFS_SUPER_MAGIC) > 0)
return -EREMOTE;
if (fd < 0)
return -errno;
+ if (flags & CHASE_SAFE) {
+ if (fstat(fd, &st) < 0)
+ return -errno;
+
+ if (!safe_transition(&previous_stat, &st))
+ return -EPERM;
+
+ previous_stat = st;
+ }
+
free(done);
/* Note that we do not revalidate the root, we take it as is. */
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 = first;
- first = NULL;
- } else {
+ 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';
/* And iterate again, but go one directory further down. */
safe_close(fd);
- fd = child;
- child = -1;
+ fd = TAKE_FD(child);
}
if (!done) {
return -ENOMEM;
}
- if (ret) {
- *ret = done;
- done = NULL;
+ 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) {
/* Like access() but operates on an already open fd */
xsprintf(p, "/proc/self/fd/%i", fd);
-
r = access(p, mode);
if (r < 0)
- r = -errno;
+ 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.", 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, *dn = 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;
+
+ dn = dirname_malloc(path);
+ if (!dn)
+ return -ENOMEM;
+
+ dfd = open(dn, O_RDONLY|O_CLOEXEC|O_DIRECTORY);
+ if (dfd < 0)
+ return -errno;
+
+ if (fsync(dfd) < 0)
+ return -errno;
+
+ return 0;
+}
~ianmdlvl / elogind.git / blobdiff