basic,shared: move a bunch of files to src/shared/

The goal is to move everything that requires selinux or smack
away from src/basic/. This means that src/basic/label.[ch] must move,
which implies btrfs-util.[ch], copy.[ch], and a bunch of other files
which form a cluster of internal use.

This is just moving text around, so there should be no functional difference.

test-blockdev-util is new, because path_is_encrypted() is moved to
blockdev-util.c, and so far we didn't have any tests for code there.

1 files changed, 316 insertions, 0 deletions

diff --git a/src/shared/rm-rf.c b/src/shared/rm-rf.c
new file mode 100644
index 0000000000..900a7fb5ff
--- /dev/null
+++ b/src/shared/rm-rf.c
@@ -0,0 +1,316 @@
+/* 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 "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"
+
+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,
+                mode_t *ret_old_mode) {
+
+        struct stat st;
+
+        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? */
+                return -EACCES; /* original error */
+        if (st.st_uid != geteuid())  /* this only works if the UID matches ours */
+                return -EACCES;
+
+        if (fchmod(dfd, (st.st_mode | 0700) & 07777) < 0)
+                return -errno;
+
+        *ret_old_mode = st.st_mode;
+        return 0;
+}
+
+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, &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);
+                return r;
+        }
+
+        if (FLAGS_SET(remove_flags, REMOVE_CHMOD_RESTORE) && fchmod(dfd, old_mode) < 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, &old_mode);
+        if (r < 0)
+                return r;
+
+        if (fstatat(dfd, filename, ret, fstatat_flags) < 0) {
+                r = -errno;
+                (void) fchmod(dfd, old_mode);
+                return r;
+        }
+
+        if (FLAGS_SET(remove_flags, REMOVE_CHMOD_RESTORE) && fchmod(dfd, old_mode) < 0)
+                return -errno;
+
+        return 0;
+}
+
+int rm_rf_children(int fd, RemoveFlags flags, struct stat *root_dev) {
+        _cleanup_closedir_ DIR *d = NULL;
+        struct dirent *de;
+        int ret = 0, r;
+        struct statfs sfs;
+
+        assert(fd >= 0);
+
+        /* This returns the first error we run into, but nevertheless tries to go on. This closes the passed
+         * fd, in all cases, including on failure.. */
+
+        if (!(flags & REMOVE_PHYSICAL)) {
+
+                r = fstatfs(fd, &sfs);
+                if (r < 0) {
+                        safe_close(fd);
+                        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);
+                        log_error("Attempted to remove disk file system under \"%s\", and we can't allow that.",
+                                  strna(path));
+
+                        safe_close(fd);
+                        return -EPERM;
+                }
+        }
+
+        d = fdopendir(fd);
+        if (!d) {
+                safe_close(fd);
+                return errno == ENOENT ? 0 : -errno;
+        }
+
+        FOREACH_DIRENT_ALL(de, d, return -errno) {
+                bool is_dir;
+                struct stat st;
+
+                if (dot_or_dot_dot(de->d_name))
+                        continue;
+
+                if (de->d_type == DT_UNKNOWN ||
+                    (de->d_type == DT_DIR && (root_dev || (flags & REMOVE_SUBVOLUME)))) {
+                        r = fstatat_harder(fd, de->d_name, &st, AT_SYMLINK_NOFOLLOW, flags);
+                        if (r < 0) {
+                                if (ret == 0 && r != -ENOENT)
+                                        ret = r;
+                                continue;
+                        }
+
+                        is_dir = S_ISDIR(st.st_mode);
+                } else
+                        is_dir = de->d_type == DT_DIR;
+
+                if (is_dir) {
+                        _cleanup_close_ int subdir_fd = -1;
+
+                        /* if root_dev is set, remove subdirectories only if device is same */
+                        if (root_dev && st.st_dev != root_dev->st_dev)
+                                continue;
+
+                        subdir_fd = openat(fd, de->d_name, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
+                        if (subdir_fd < 0) {
+                                if (ret == 0 && errno != ENOENT)
+                                        ret = -errno;
+                                continue;
+                        }
+
+                        /* Stop at mount points */
+                        r = fd_is_mount_point(fd, de->d_name, 0);
+                        if (r < 0) {
+                                if (ret == 0 && r != -ENOENT)
+                                        ret = r;
+
+                                continue;
+                        }
+                        if (r > 0)
+                                continue;
+
+                        if ((flags & REMOVE_SUBVOLUME) && btrfs_might_be_subvol(&st)) {
+
+                                /* This could be a subvolume, try to remove it */
+
+                                r = btrfs_subvol_remove_fd(fd, de->d_name, BTRFS_REMOVE_RECURSIVE|BTRFS_REMOVE_QUOTA);
+                                if (r < 0) {
+                                        if (!IN_SET(r, -ENOTTY, -EINVAL)) {
+                                                if (ret == 0)
+                                                        ret = r;
+
+                                                continue;
+                                        }
+
+                                        /* ENOTTY, then it wasn't a btrfs subvolume, continue below. */
+                                } else
+                                        /* It was a subvolume, continue. */
+                                        continue;
+                        }
+
+                        /* We pass REMOVE_PHYSICAL here, to avoid doing the fstatfs() to check the file
+                         * system type again for each directory */
+                        r = rm_rf_children(TAKE_FD(subdir_fd), flags | REMOVE_PHYSICAL, root_dev);
+                        if (r < 0 && ret == 0)
+                                ret = r;
+
+                        r = unlinkat_harder(fd, de->d_name, AT_REMOVEDIR, flags);
+                        if (r < 0 && r != -ENOENT && ret == 0)
+                                ret = r;
+
+                } else if (!(flags & REMOVE_ONLY_DIRECTORIES)) {
+
+                        r = unlinkat_harder(fd, de->d_name, 0, flags);
+                        if (r < 0 && r != -ENOENT && ret == 0)
+                                ret = r;
+                }
+        }
+        return ret;
+}
+
+int rm_rf(const char *path, RemoveFlags flags) {
+        int fd, r;
+        struct statfs s;
+
+        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_equal_or_files_same(path, "/", AT_SYMLINK_NOFOLLOW))
+                return log_error_errno(SYNTHETIC_ERRNO(EPERM),
+                                       "Attempted to remove entire root file system (\"%s\"), and we can't allow that.",
+                                       path);
+
+        if (FLAGS_SET(flags, REMOVE_SUBVOLUME | REMOVE_ROOT | REMOVE_PHYSICAL)) {
+                /* Try to remove as subvolume first */
+                r = btrfs_subvol_remove(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 = open(path, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
+        if (fd < 0) {
+                if (FLAGS_SET(flags, REMOVE_MISSING_OK) && errno == ENOENT)
+                        return 0;
+
+                if (!IN_SET(errno, ENOTDIR, ELOOP))
+                        return -errno;
+
+                if (FLAGS_SET(flags, REMOVE_ONLY_DIRECTORIES))
+                        return 0;
+
+                if (FLAGS_SET(flags, REMOVE_ROOT)) {
+
+                        if (!FLAGS_SET(flags, REMOVE_PHYSICAL)) {
+                                if (statfs(path, &s) < 0)
+                                        return -errno;
+
+                                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);
+                        }
+
+                        if (unlink(path) < 0) {
+                                if (FLAGS_SET(flags, REMOVE_MISSING_OK) && errno == ENOENT)
+                                        return 0;
+
+                                return -errno;
+                        }
+                }
+
+                return 0;
+        }
+
+        r = rm_rf_children(fd, flags, NULL);
+
+        if (FLAGS_SET(flags, REMOVE_ROOT) &&
+            rmdir(path) < 0 &&
+            r >= 0 &&
+            (!FLAGS_SET(flags, REMOVE_MISSING_OK) || errno != ENOENT))
+                r = -errno;
+
+        return r;
+}