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-rw-r--r--src/shared/rm-rf.c519
1 files changed, 519 insertions, 0 deletions
diff --git a/src/shared/rm-rf.c b/src/shared/rm-rf.c
new file mode 100644
index 0000000..4664215
--- /dev/null
+++ b/src/shared/rm-rf.c
@@ -0,0 +1,519 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "btrfs-util.h"
+#include "cgroup-util.h"
+#include "dirent-util.h"
+#include "fd-util.h"
+#include "fs-util.h"
+#include "log.h"
+#include "macro.h"
+#include "mountpoint-util.h"
+#include "path-util.h"
+#include "rm-rf.h"
+#include "stat-util.h"
+#include "string-util.h"
+
+/* We treat tmpfs/ramfs + cgroupfs as non-physical file systems. cgroupfs is similar to tmpfs in a way
+ * after all: we can create arbitrary directory hierarchies in it, and hence can also use rm_rf() on it
+ * to remove those again. */
+static bool is_physical_fs(const struct statfs *sfs) {
+ return !is_temporary_fs(sfs) && !is_cgroup_fs(sfs);
+}
+
+static int patch_dirfd_mode(
+ int dfd,
+ bool refuse_already_set,
+ mode_t *ret_old_mode) {
+
+ struct stat st;
+ int r;
+
+ assert(dfd >= 0);
+ assert(ret_old_mode);
+
+ if (fstat(dfd, &st) < 0)
+ return -errno;
+ if (!S_ISDIR(st.st_mode))
+ return -ENOTDIR;
+
+ if (FLAGS_SET(st.st_mode, 0700)) { /* Already set? */
+ if (refuse_already_set)
+ return -EACCES; /* original error */
+
+ *ret_old_mode = st.st_mode;
+ return 0;
+ }
+
+ if (st.st_uid != geteuid()) /* this only works if the UID matches ours */
+ return -EACCES;
+
+ r = fchmod_opath(dfd, (st.st_mode | 0700) & 07777);
+ if (r < 0)
+ return r;
+
+ *ret_old_mode = st.st_mode;
+ return 1;
+}
+
+int unlinkat_harder(int dfd, const char *filename, int unlink_flags, RemoveFlags remove_flags) {
+ mode_t old_mode;
+ int r;
+
+ /* Like unlinkat(), but tries harder: if we get EACCESS we'll try to set the r/w/x bits on the
+ * directory. This is useful if we run unprivileged and have some files where the w bit is
+ * missing. */
+
+ if (unlinkat(dfd, filename, unlink_flags) >= 0)
+ return 0;
+ if (errno != EACCES || !FLAGS_SET(remove_flags, REMOVE_CHMOD))
+ return -errno;
+
+ r = patch_dirfd_mode(dfd, /* refuse_already_set = */ true, &old_mode);
+ if (r < 0)
+ return r;
+
+ if (unlinkat(dfd, filename, unlink_flags) < 0) {
+ r = -errno;
+ /* Try to restore the original access mode if this didn't work */
+ (void) fchmod(dfd, old_mode & 07777);
+ return r;
+ }
+
+ if (FLAGS_SET(remove_flags, REMOVE_CHMOD_RESTORE) && fchmod(dfd, old_mode & 07777) < 0)
+ return -errno;
+
+ /* If this worked, we won't reset the old mode by default, since we'll need it for other entries too,
+ * and we should destroy the whole thing */
+ return 0;
+}
+
+int fstatat_harder(int dfd,
+ const char *filename,
+ struct stat *ret,
+ int fstatat_flags,
+ RemoveFlags remove_flags) {
+
+ mode_t old_mode;
+ int r;
+
+ /* Like unlink_harder() but does the same for fstatat() */
+
+ if (fstatat(dfd, filename, ret, fstatat_flags) >= 0)
+ return 0;
+ if (errno != EACCES || !FLAGS_SET(remove_flags, REMOVE_CHMOD))
+ return -errno;
+
+ r = patch_dirfd_mode(dfd, /* refuse_already_set = */ true, &old_mode);
+ if (r < 0)
+ return r;
+
+ if (fstatat(dfd, filename, ret, fstatat_flags) < 0) {
+ r = -errno;
+ (void) fchmod(dfd, old_mode & 07777);
+ return r;
+ }
+
+ if (FLAGS_SET(remove_flags, REMOVE_CHMOD_RESTORE) && fchmod(dfd, old_mode & 07777) < 0)
+ return -errno;
+
+ return 0;
+}
+
+static int openat_harder(int dfd, const char *path, int open_flags, RemoveFlags remove_flags, mode_t *ret_old_mode) {
+ _cleanup_close_ int pfd = -EBADF, fd = -EBADF;
+ bool chmod_done = false;
+ mode_t old_mode;
+ int r;
+
+ assert(dfd >= 0 || dfd == AT_FDCWD);
+ assert(path);
+
+ /* Unlike unlink_harder() and fstatat_harder(), this chmod the specified path. */
+
+ if (FLAGS_SET(open_flags, O_PATH) ||
+ !FLAGS_SET(open_flags, O_DIRECTORY) ||
+ !FLAGS_SET(remove_flags, REMOVE_CHMOD)) {
+
+ fd = RET_NERRNO(openat(dfd, path, open_flags));
+ if (fd < 0)
+ return fd;
+
+ if (ret_old_mode) {
+ struct stat st;
+
+ if (fstat(fd, &st) < 0)
+ return -errno;
+
+ *ret_old_mode = st.st_mode;
+ }
+
+ return TAKE_FD(fd);
+ }
+
+ pfd = RET_NERRNO(openat(dfd, path, (open_flags & (O_CLOEXEC|O_DIRECTORY|O_NOFOLLOW)) | O_PATH));
+ if (pfd < 0)
+ return pfd;
+
+ if (FLAGS_SET(remove_flags, REMOVE_CHMOD)) {
+ r = patch_dirfd_mode(pfd, /* refuse_already_set = */ false, &old_mode);
+ if (r < 0)
+ return r;
+
+ chmod_done = r;
+ }
+
+ fd = fd_reopen(pfd, open_flags & ~O_NOFOLLOW);
+ if (fd < 0) {
+ if (chmod_done)
+ (void) fchmod_opath(pfd, old_mode & 07777);
+ return fd;
+ }
+
+ if (ret_old_mode)
+ *ret_old_mode = old_mode;
+
+ return TAKE_FD(fd);
+}
+
+static int rm_rf_children_impl(
+ int fd,
+ RemoveFlags flags,
+ const struct stat *root_dev,
+ mode_t old_mode);
+
+static int rm_rf_inner_child(
+ int fd,
+ const char *fname,
+ int is_dir,
+ RemoveFlags flags,
+ const struct stat *root_dev,
+ bool allow_recursion) {
+
+ struct stat st;
+ int r, q = 0;
+
+ assert(fd >= 0);
+ assert(fname);
+
+ if (is_dir < 0 ||
+ root_dev ||
+ (is_dir > 0 && (root_dev || (flags & REMOVE_SUBVOLUME)))) {
+
+ r = fstatat_harder(fd, fname, &st, AT_SYMLINK_NOFOLLOW, flags);
+ if (r < 0)
+ return r;
+
+ is_dir = S_ISDIR(st.st_mode);
+ }
+
+ if (is_dir) {
+ /* If root_dev is set, remove subdirectories only if device is same */
+ if (root_dev && st.st_dev != root_dev->st_dev)
+ return 0;
+
+ /* Stop at mount points */
+ r = fd_is_mount_point(fd, fname, 0);
+ if (r < 0)
+ return r;
+ if (r > 0)
+ return 0;
+
+ if ((flags & REMOVE_SUBVOLUME) && btrfs_might_be_subvol(&st)) {
+ /* This could be a subvolume, try to remove it */
+
+ r = btrfs_subvol_remove_at(fd, fname, BTRFS_REMOVE_RECURSIVE|BTRFS_REMOVE_QUOTA);
+ if (r < 0) {
+ if (!IN_SET(r, -ENOTTY, -EINVAL))
+ return r;
+
+ /* ENOTTY, then it wasn't a btrfs subvolume, continue below. */
+ } else
+ /* It was a subvolume, done. */
+ return 1;
+ }
+
+ if (!allow_recursion)
+ return -EISDIR;
+
+ mode_t old_mode;
+ int subdir_fd = openat_harder(fd, fname,
+ O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME,
+ flags, &old_mode);
+ if (subdir_fd < 0)
+ return subdir_fd;
+
+ /* We pass REMOVE_PHYSICAL here, to avoid doing the fstatfs() to check the file system type
+ * again for each directory */
+ q = rm_rf_children_impl(subdir_fd, flags | REMOVE_PHYSICAL, root_dev, old_mode);
+
+ } else if (flags & REMOVE_ONLY_DIRECTORIES)
+ return 0;
+
+ r = unlinkat_harder(fd, fname, is_dir ? AT_REMOVEDIR : 0, flags);
+ if (r < 0)
+ return r;
+ if (q < 0)
+ return q;
+ return 1;
+}
+
+typedef struct TodoEntry {
+ DIR *dir; /* A directory that we were operating on. */
+ char *dirname; /* The filename of that directory itself. */
+ mode_t old_mode; /* The original file mode. */
+} TodoEntry;
+
+static void free_todo_entries(TodoEntry **todos) {
+ for (TodoEntry *x = *todos; x && x->dir; x++) {
+ closedir(x->dir);
+ free(x->dirname);
+ }
+
+ freep(todos);
+}
+
+int rm_rf_children(
+ int fd,
+ RemoveFlags flags,
+ const struct stat *root_dev) {
+
+ struct stat st;
+
+ assert(fd >= 0);
+
+ if (fstat(fd, &st) < 0)
+ return -errno;
+
+ return rm_rf_children_impl(fd, flags, root_dev, st.st_mode);
+}
+
+static int rm_rf_children_impl(
+ int fd,
+ RemoveFlags flags,
+ const struct stat *root_dev,
+ mode_t old_mode) {
+
+ _cleanup_(free_todo_entries) TodoEntry *todos = NULL;
+ size_t n_todo = 0;
+ _cleanup_free_ char *dirname = NULL; /* Set when we are recursing and want to delete ourselves */
+ int ret = 0, r;
+
+ /* Return the first error we run into, but nevertheless try to go on.
+ * The passed fd is closed in all cases, including on failure. */
+
+ for (;;) { /* This loop corresponds to the directory nesting level. */
+ _cleanup_closedir_ DIR *d = NULL;
+
+ if (n_todo > 0) {
+ /* We know that we are in recursion here, because n_todo is set.
+ * We need to remove the inner directory we were operating on. */
+ assert(dirname);
+ r = unlinkat_harder(dirfd(todos[n_todo-1].dir), dirname, AT_REMOVEDIR, flags);
+ if (r < 0 && r != -ENOENT) {
+ if (ret == 0)
+ ret = r;
+
+ if (FLAGS_SET(flags, REMOVE_CHMOD_RESTORE))
+ (void) fchmodat(dirfd(todos[n_todo-1].dir), dirname, old_mode & 07777, 0);
+ }
+ dirname = mfree(dirname);
+
+ /* And now let's back out one level up */
+ n_todo --;
+ d = TAKE_PTR(todos[n_todo].dir);
+ dirname = TAKE_PTR(todos[n_todo].dirname);
+ old_mode = todos[n_todo].old_mode;
+
+ assert(d);
+ fd = dirfd(d); /* Retrieve the file descriptor from the DIR object */
+ assert(fd >= 0);
+ } else {
+ next_fd:
+ assert(fd >= 0);
+ d = fdopendir(fd);
+ if (!d) {
+ safe_close(fd);
+ return -errno;
+ }
+ fd = dirfd(d); /* We donated the fd to fdopendir(). Let's make sure we sure we have
+ * the right descriptor even if it were to internally invalidate the
+ * one we passed. */
+
+ if (!(flags & REMOVE_PHYSICAL)) {
+ struct statfs sfs;
+
+ if (fstatfs(fd, &sfs) < 0)
+ return -errno;
+
+ if (is_physical_fs(&sfs)) {
+ /* We refuse to clean physical file systems with this call, unless
+ * explicitly requested. This is extra paranoia just to be sure we
+ * never ever remove non-state data. */
+
+ _cleanup_free_ char *path = NULL;
+
+ (void) fd_get_path(fd, &path);
+ return log_error_errno(SYNTHETIC_ERRNO(EPERM),
+ "Attempted to remove disk file system under \"%s\", and we can't allow that.",
+ strna(path));
+ }
+ }
+ }
+
+ FOREACH_DIRENT_ALL(de, d, return -errno) {
+ int is_dir;
+
+ if (dot_or_dot_dot(de->d_name))
+ continue;
+
+ is_dir = de->d_type == DT_UNKNOWN ? -1 : de->d_type == DT_DIR;
+
+ r = rm_rf_inner_child(fd, de->d_name, is_dir, flags, root_dev, false);
+ if (r == -EISDIR) {
+ /* Push the current working state onto the todo list */
+
+ if (!GREEDY_REALLOC0(todos, n_todo + 2))
+ return log_oom();
+
+ _cleanup_free_ char *newdirname = strdup(de->d_name);
+ if (!newdirname)
+ return log_oom();
+
+ mode_t mode;
+ int newfd = openat_harder(fd, de->d_name,
+ O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME,
+ flags, &mode);
+ if (newfd >= 0) {
+ todos[n_todo++] = (TodoEntry) {
+ .dir = TAKE_PTR(d),
+ .dirname = TAKE_PTR(dirname),
+ .old_mode = old_mode
+ };
+
+ fd = newfd;
+ dirname = TAKE_PTR(newdirname);
+ old_mode = mode;
+
+ goto next_fd;
+
+ } else if (newfd != -ENOENT && ret == 0)
+ ret = newfd;
+
+ } else if (r < 0 && r != -ENOENT && ret == 0)
+ ret = r;
+ }
+
+ if (FLAGS_SET(flags, REMOVE_SYNCFS) && syncfs(fd) < 0 && ret >= 0)
+ ret = -errno;
+
+ if (n_todo == 0) {
+ if (FLAGS_SET(flags, REMOVE_CHMOD_RESTORE) &&
+ fchmod(fd, old_mode & 07777) < 0 && ret >= 0)
+ ret = -errno;
+
+ break;
+ }
+ }
+
+ return ret;
+}
+
+int rm_rf_at(int dir_fd, const char *path, RemoveFlags flags) {
+ mode_t old_mode;
+ int fd, r, q = 0;
+
+ assert(dir_fd >= 0 || dir_fd == AT_FDCWD);
+ assert(path);
+
+ /* For now, don't support dropping subvols when also only dropping directories, since we can't do
+ * this race-freely. */
+ if (FLAGS_SET(flags, REMOVE_ONLY_DIRECTORIES|REMOVE_SUBVOLUME))
+ return -EINVAL;
+
+ /* We refuse to clean the root file system with this call. This is extra paranoia to never cause a
+ * really seriously broken system. */
+ if (path_is_root_at(dir_fd, path) > 0)
+ return log_error_errno(SYNTHETIC_ERRNO(EPERM),
+ "Attempted to remove entire root file system, and we can't allow that.");
+
+ if (FLAGS_SET(flags, REMOVE_SUBVOLUME | REMOVE_ROOT | REMOVE_PHYSICAL)) {
+ /* Try to remove as subvolume first */
+ r = btrfs_subvol_remove_at(dir_fd, path, BTRFS_REMOVE_RECURSIVE|BTRFS_REMOVE_QUOTA);
+ if (r >= 0)
+ return r;
+
+ if (FLAGS_SET(flags, REMOVE_MISSING_OK) && r == -ENOENT)
+ return 0;
+
+ if (!IN_SET(r, -ENOTTY, -EINVAL, -ENOTDIR))
+ return r;
+
+ /* Not btrfs or not a subvolume */
+ }
+
+ fd = openat_harder(dir_fd, path, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME, flags, &old_mode);
+ if (fd >= 0) {
+ /* We have a dir */
+ r = rm_rf_children_impl(fd, flags, NULL, old_mode);
+
+ if (FLAGS_SET(flags, REMOVE_ROOT))
+ q = RET_NERRNO(unlinkat(dir_fd, path, AT_REMOVEDIR));
+ } else {
+ r = fd;
+ if (FLAGS_SET(flags, REMOVE_MISSING_OK) && r == -ENOENT)
+ return 0;
+
+ if (!IN_SET(r, -ENOTDIR, -ELOOP))
+ return r;
+
+ if (FLAGS_SET(flags, REMOVE_ONLY_DIRECTORIES) || !FLAGS_SET(flags, REMOVE_ROOT))
+ return 0;
+
+ if (!FLAGS_SET(flags, REMOVE_PHYSICAL)) {
+ struct statfs s;
+
+ r = xstatfsat(dir_fd, path, &s);
+ if (r < 0)
+ return r;
+ if (is_physical_fs(&s))
+ return log_error_errno(SYNTHETIC_ERRNO(EPERM),
+ "Attempted to remove files from a disk file system under \"%s\", refusing.",
+ path);
+ }
+
+ r = 0;
+ q = RET_NERRNO(unlinkat(dir_fd, path, 0));
+ }
+
+ if (r < 0)
+ return r;
+ if (q < 0 && (q != -ENOENT || !FLAGS_SET(flags, REMOVE_MISSING_OK)))
+ return q;
+ return 0;
+}
+
+int rm_rf_child(int fd, const char *name, RemoveFlags flags) {
+
+ /* Removes one specific child of the specified directory */
+
+ if (fd < 0)
+ return -EBADF;
+
+ if (!filename_is_valid(name))
+ return -EINVAL;
+
+ if ((flags & (REMOVE_ROOT|REMOVE_MISSING_OK)) != 0) /* Doesn't really make sense here, we are not supposed to remove 'fd' anyway */
+ return -EINVAL;
+
+ if (FLAGS_SET(flags, REMOVE_ONLY_DIRECTORIES|REMOVE_SUBVOLUME))
+ return -EINVAL;
+
+ return rm_rf_inner_child(fd, name, -1, flags, NULL, true);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-11 16:03:30 +0000