[systemd.git] / src / basic / rm-rf.c

/* 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;
}
Commit	Line	Data
a032b68d	1	/* SPDX-License-Identifier: LGPL-2.1-or-later */
e3bff60a	2
4c89c718 MP	3	#include <errno.h>
	4	#include <fcntl.h>
	5	#include <stdbool.h>
	6	#include <stddef.h>
4c89c718 MP	7	#include <unistd.h>
4c89c718 MP	8
b012e921	9	#include "alloc-util.h"
e3bff60a	10	#include "btrfs-util.h"
8a584da2	11	#include "cgroup-util.h"
2897b343	12	#include "dirent-util.h"
db2df898	13	#include "fd-util.h"
4c89c718 MP	14	#include "log.h"
4c89c718 MP	15	#include "macro.h"
6e866b33	16	#include "mountpoint-util.h"
db2df898	17	#include "path-util.h"
e3bff60a	18	#include "rm-rf.h"
db2df898 MP	19	#include "stat-util.h"
db2df898 MP	20	#include "string-util.h"
e3bff60a	21
8a584da2 MP	22	static bool is_physical_fs(const struct statfs *sfs) {
	23	return !is_temporary_fs(sfs) && !is_cgroup_fs(sfs);
	24	}
	25
3a6ce677 BR	26	static int patch_dirfd_mode(
	27	int dfd,
	28	mode_t *ret_old_mode) {
	29
	30	struct stat st;
	31
	32	assert(dfd >= 0);
	33	assert(ret_old_mode);
	34
	35	if (fstat(dfd, &st) < 0)
	36	return -errno;
	37	if (!S_ISDIR(st.st_mode))
	38	return -ENOTDIR;
	39	if (FLAGS_SET(st.st_mode, 0700)) /* Already set? */
	40	return -EACCES; /* original error */
	41	if (st.st_uid != geteuid()) /* this only works if the UID matches ours */
	42	return -EACCES;
	43
	44	if (fchmod(dfd, (st.st_mode \| 0700) & 07777) < 0)
	45	return -errno;
	46
	47	*ret_old_mode = st.st_mode;
	48	return 0;
	49	}
	50
8b3d4ff0	51	int unlinkat_harder(int dfd, const char *filename, int unlink_flags, RemoveFlags remove_flags) {
a032b68d	52
3a6ce677	53	mode_t old_mode;
a032b68d MB	54	int r;
	55
	56	/* Like unlinkat(), but tries harder: if we get EACCESS we'll try to set the r/w/x bits on the
	57	* directory. This is useful if we run unprivileged and have some files where the w bit is
	58	* missing. */
	59
	60	if (unlinkat(dfd, filename, unlink_flags) >= 0)
	61	return 0;
	62	if (errno != EACCES \|\| !FLAGS_SET(remove_flags, REMOVE_CHMOD))
	63	return -errno;
	64
3a6ce677 BR	65	r = patch_dirfd_mode(dfd, &old_mode);
	66	if (r < 0)
	67	return r;
a032b68d MB	68
	69	if (unlinkat(dfd, filename, unlink_flags) < 0) {
	70	r = -errno;
	71	/* Try to restore the original access mode if this didn't work */
3a6ce677 BR	72	(void) fchmod(dfd, old_mode);
	73	return r;
	74	}
	75
8b3d4ff0 MB	76	if (FLAGS_SET(remove_flags, REMOVE_CHMOD_RESTORE) && fchmod(dfd, old_mode) < 0)
	77	return -errno;
	78
	79	/* If this worked, we won't reset the old mode by default, since we'll need it for other entries too,
	80	* and we should destroy the whole thing */
3a6ce677 BR	81	return 0;
	82	}
	83
8b3d4ff0	84	int fstatat_harder(int dfd,
3a6ce677 BR	85	const char *filename,
	86	struct stat *ret,
	87	int fstatat_flags,
	88	RemoveFlags remove_flags) {
	89
	90	mode_t old_mode;
	91	int r;
	92
	93	/* Like unlink_harder() but does the same for fstatat() */
	94
	95	if (fstatat(dfd, filename, ret, fstatat_flags) >= 0)
	96	return 0;
	97	if (errno != EACCES \|\| !FLAGS_SET(remove_flags, REMOVE_CHMOD))
	98	return -errno;
	99
	100	r = patch_dirfd_mode(dfd, &old_mode);
	101	if (r < 0)
	102	return r;
	103
	104	if (fstatat(dfd, filename, ret, fstatat_flags) < 0) {
	105	r = -errno;
	106	(void) fchmod(dfd, old_mode);
a032b68d MB	107	return r;
	108	}
	109
8b3d4ff0 MB	110	if (FLAGS_SET(remove_flags, REMOVE_CHMOD_RESTORE) && fchmod(dfd, old_mode) < 0)
	111	return -errno;
	112
a032b68d MB	113	return 0;
	114	}
	115
e3bff60a MP	116	int rm_rf_children(int fd, RemoveFlags flags, struct stat *root_dev) {
e3bff60a MP	117	_cleanup_closedir_ DIR *d = NULL;
2897b343	118	struct dirent *de;
e3bff60a	119	int ret = 0, r;
8a584da2	120	struct statfs sfs;
e3bff60a MP	121
	122	assert(fd >= 0);
	123
f2dec872 BR	124	/* This returns the first error we run into, but nevertheless tries to go on. This closes the passed
f2dec872 BR	125	* fd, in all cases, including on failure.. */
e3bff60a MP	126
	127	if (!(flags & REMOVE_PHYSICAL)) {
	128
8a584da2	129	r = fstatfs(fd, &sfs);
e3bff60a MP	130	if (r < 0) {
e3bff60a MP	131	safe_close(fd);
8a584da2	132	return -errno;
e3bff60a MP	133	}
e3bff60a MP	134
8a584da2	135	if (is_physical_fs(&sfs)) {
b012e921 MB	136	/* We refuse to clean physical file systems with this call,
	137	* unless explicitly requested. This is extra paranoia just
	138	* to be sure we never ever remove non-state data. */
	139	_cleanup_free_ char *path = NULL;
	140
	141	(void) fd_get_path(fd, &path);
	142	log_error("Attempted to remove disk file system under \"%s\", and we can't allow that.",
	143	strna(path));
e3bff60a	144
e3bff60a MP	145	safe_close(fd);
	146	return -EPERM;
	147	}
	148	}
	149
	150	d = fdopendir(fd);
	151	if (!d) {
	152	safe_close(fd);
	153	return errno == ENOENT ? 0 : -errno;
	154	}
	155
2897b343	156	FOREACH_DIRENT_ALL(de, d, return -errno) {
e3bff60a MP	157	bool is_dir;
	158	struct stat st;
	159
2897b343	160	if (dot_or_dot_dot(de->d_name))
e3bff60a MP	161	continue;
	162
	163	if (de->d_type == DT_UNKNOWN \|\|
	164	(de->d_type == DT_DIR && (root_dev \|\| (flags & REMOVE_SUBVOLUME)))) {
3a6ce677 BR	165	r = fstatat_harder(fd, de->d_name, &st, AT_SYMLINK_NOFOLLOW, flags);
	166	if (r < 0) {
	167	if (ret == 0 && r != -ENOENT)
	168	ret = r;
e3bff60a MP	169	continue;
	170	}
	171
	172	is_dir = S_ISDIR(st.st_mode);
	173	} else
	174	is_dir = de->d_type == DT_DIR;
	175
	176	if (is_dir) {
f2dec872	177	_cleanup_close_ int subdir_fd = -1;
e3bff60a MP	178
	179	/* if root_dev is set, remove subdirectories only if device is same */
	180	if (root_dev && st.st_dev != root_dev->st_dev)
	181	continue;
	182
	183	subdir_fd = openat(fd, de->d_name, O_RDONLY\|O_NONBLOCK\|O_DIRECTORY\|O_CLOEXEC\|O_NOFOLLOW\|O_NOATIME);
	184	if (subdir_fd < 0) {
	185	if (ret == 0 && errno != ENOENT)
	186	ret = -errno;
	187	continue;
	188	}
	189
	190	/* Stop at mount points */
86f210e9	191	r = fd_is_mount_point(fd, de->d_name, 0);
e3bff60a MP	192	if (r < 0) {
	193	if (ret == 0 && r != -ENOENT)
	194	ret = r;
	195
e3bff60a MP	196	continue;
e3bff60a MP	197	}
f2dec872	198	if (r > 0)
e3bff60a	199	continue;
e3bff60a	200
3a6ce677	201	if ((flags & REMOVE_SUBVOLUME) && btrfs_might_be_subvol(&st)) {
e3bff60a MP	202
	203	/* This could be a subvolume, try to remove it */
	204
db2df898	205	r = btrfs_subvol_remove_fd(fd, de->d_name, BTRFS_REMOVE_RECURSIVE\|BTRFS_REMOVE_QUOTA);
e3bff60a	206	if (r < 0) {
f5e65279	207	if (!IN_SET(r, -ENOTTY, -EINVAL)) {
e3bff60a MP	208	if (ret == 0)
	209	ret = r;
	210
e3bff60a MP	211	continue;
	212	}
	213
f2dec872 BR	214	/* ENOTTY, then it wasn't a btrfs subvolume, continue below. */
f2dec872 BR	215	} else
e3bff60a	216	/* It was a subvolume, continue. */
e3bff60a	217	continue;
e3bff60a MP	218	}
e3bff60a MP	219
f2dec872	220	/* We pass REMOVE_PHYSICAL here, to avoid doing the fstatfs() to check the file
e3bff60a	221	* system type again for each directory */
f2dec872	222	r = rm_rf_children(TAKE_FD(subdir_fd), flags \| REMOVE_PHYSICAL, root_dev);
e3bff60a MP	223	if (r < 0 && ret == 0)
	224	ret = r;
	225
a032b68d MB	226	r = unlinkat_harder(fd, de->d_name, AT_REMOVEDIR, flags);
	227	if (r < 0 && r != -ENOENT && ret == 0)
	228	ret = r;
e3bff60a MP	229
	230	} else if (!(flags & REMOVE_ONLY_DIRECTORIES)) {
	231
a032b68d MB	232	r = unlinkat_harder(fd, de->d_name, 0, flags);
	233	if (r < 0 && r != -ENOENT && ret == 0)
	234	ret = r;
e3bff60a MP	235	}
e3bff60a MP	236	}
2897b343	237	return ret;
e3bff60a MP	238	}
	239
	240	int rm_rf(const char *path, RemoveFlags flags) {
	241	int fd, r;
	242	struct statfs s;
	243
	244	assert(path);
	245
bb4f798a MB	246	/* For now, don't support dropping subvols when also only dropping directories, since we can't do
	247	* this race-freely. */
	248	if (FLAGS_SET(flags, REMOVE_ONLY_DIRECTORIES\|REMOVE_SUBVOLUME))
	249	return -EINVAL;
	250
f2dec872 BR	251	/* We refuse to clean the root file system with this call. This is extra paranoia to never cause a
f2dec872 BR	252	* really seriously broken system. */
6e866b33 MB	253	if (path_equal_or_files_same(path, "/", AT_SYMLINK_NOFOLLOW))
	254	return log_error_errno(SYNTHETIC_ERRNO(EPERM),
	255	"Attempted to remove entire root file system (\"%s\"), and we can't allow that.",
	256	path);
e3bff60a	257
b012e921	258	if (FLAGS_SET(flags, REMOVE_SUBVOLUME \| REMOVE_ROOT \| REMOVE_PHYSICAL)) {
e3bff60a	259	/* Try to remove as subvolume first */
db2df898	260	r = btrfs_subvol_remove(path, BTRFS_REMOVE_RECURSIVE\|BTRFS_REMOVE_QUOTA);
e3bff60a MP	261	if (r >= 0)
	262	return r;
	263
f2dec872 BR	264	if (FLAGS_SET(flags, REMOVE_MISSING_OK) && r == -ENOENT)
	265	return 0;
	266
f5e65279	267	if (!IN_SET(r, -ENOTTY, -EINVAL, -ENOTDIR))
e3bff60a MP	268	return r;
	269
	270	/* Not btrfs or not a subvolume */
	271	}
	272
	273	fd = open(path, O_RDONLY\|O_NONBLOCK\|O_DIRECTORY\|O_CLOEXEC\|O_NOFOLLOW\|O_NOATIME);
	274	if (fd < 0) {
f2dec872 BR	275	if (FLAGS_SET(flags, REMOVE_MISSING_OK) && errno == ENOENT)
	276	return 0;
	277
f5e65279	278	if (!IN_SET(errno, ENOTDIR, ELOOP))
e3bff60a MP	279	return -errno;
e3bff60a MP	280
f2dec872 BR	281	if (FLAGS_SET(flags, REMOVE_ONLY_DIRECTORIES))
f2dec872 BR	282	return 0;
e3bff60a	283
f2dec872 BR	284	if (FLAGS_SET(flags, REMOVE_ROOT)) {
	285
	286	if (!FLAGS_SET(flags, REMOVE_PHYSICAL)) {
	287	if (statfs(path, &s) < 0)
	288	return -errno;
	289
	290	if (is_physical_fs(&s))
	291	return log_error_errno(SYNTHETIC_ERRNO(EPERM),
	292	"Attempted to remove files from a disk file system under \"%s\", refusing.",
	293	path);
	294	}
	295
	296	if (unlink(path) < 0) {
	297	if (FLAGS_SET(flags, REMOVE_MISSING_OK) && errno == ENOENT)
	298	return 0;
e3bff60a	299
e3bff60a	300	return -errno;
f2dec872 BR	301	}
f2dec872 BR	302	}
e3bff60a MP	303
	304	return 0;
	305	}
	306
	307	r = rm_rf_children(fd, flags, NULL);
	308
f2dec872 BR	309	if (FLAGS_SET(flags, REMOVE_ROOT) &&
	310	rmdir(path) < 0 &&
	311	r >= 0 &&
	312	(!FLAGS_SET(flags, REMOVE_MISSING_OK) \|\| errno != ENOENT))
	313	r = -errno;
e3bff60a MP	314
	315	return r;
	316	}