src/basic/rm-rf.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <errno.h>
   4 #include <fcntl.h>
   5 #include <stdbool.h>
   6 #include <stddef.h>
   7 #include <sys/stat.h>
   8 #include <sys/statfs.h>
   9 #include <unistd.h>
  10
  11 #include "alloc-util.h"
  12 #include "btrfs-util.h"
  13 #include "cgroup-util.h"
  14 #include "dirent-util.h"
  15 #include "fd-util.h"
  16 #include "log.h"
  17 #include "macro.h"
  18 #include "mountpoint-util.h"
  19 #include "path-util.h"
  20 #include "rm-rf.h"
  21 #include "stat-util.h"
  22 #include "string-util.h"
  23
  24 static bool is_physical_fs(const struct statfs *sfs) {
  25         return !is_temporary_fs(sfs) && !is_cgroup_fs(sfs);
  26 }
  27
  28 int rm_rf_children(int fd, RemoveFlags flags, struct stat *root_dev) {
  29         _cleanup_closedir_ DIR *d = NULL;
  30         struct dirent *de;
  31         int ret = 0, r;
  32         struct statfs sfs;
  33
  34         assert(fd >= 0);
  35
  36         /* This returns the first error we run into, but nevertheless tries to go on. This closes the passed
  37          * fd, in all cases, including on failure.. */
  38
  39         if (!(flags & REMOVE_PHYSICAL)) {
  40
  41                 r = fstatfs(fd, &sfs);
  42                 if (r < 0) {
  43                         safe_close(fd);
  44                         return -errno;
  45                 }
  46
  47                 if (is_physical_fs(&sfs)) {
  48                         /* We refuse to clean physical file systems with this call,
  49                          * unless explicitly requested. This is extra paranoia just
  50                          * to be sure we never ever remove non-state data. */
  51                         _cleanup_free_ char *path = NULL;
  52
  53                         (void) fd_get_path(fd, &path);
  54                         log_error("Attempted to remove disk file system under \"%s\", and we can't allow that.",
  55                                   strna(path));
  56
  57                         safe_close(fd);
  58                         return -EPERM;
  59                 }
  60         }
  61
  62         d = fdopendir(fd);
  63         if (!d) {
  64                 safe_close(fd);
  65                 return errno == ENOENT ? 0 : -errno;
  66         }
  67
  68         FOREACH_DIRENT_ALL(de, d, return -errno) {
  69                 bool is_dir;
  70                 struct stat st;
  71
  72                 if (dot_or_dot_dot(de->d_name))
  73                         continue;
  74
  75                 if (de->d_type == DT_UNKNOWN ||
  76                     (de->d_type == DT_DIR && (root_dev || (flags & REMOVE_SUBVOLUME)))) {
  77                         if (fstatat(fd, de->d_name, &st, AT_SYMLINK_NOFOLLOW) < 0) {
  78                                 if (ret == 0 && errno != ENOENT)
  79                                         ret = -errno;
  80                                 continue;
  81                         }
  82
  83                         is_dir = S_ISDIR(st.st_mode);
  84                 } else
  85                         is_dir = de->d_type == DT_DIR;
  86
  87                 if (is_dir) {
  88                         _cleanup_close_ int subdir_fd = -1;
  89
  90                         /* if root_dev is set, remove subdirectories only if device is same */
  91                         if (root_dev && st.st_dev != root_dev->st_dev)
  92                                 continue;
  93
  94                         subdir_fd = openat(fd, de->d_name, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
  95                         if (subdir_fd < 0) {
  96                                 if (ret == 0 && errno != ENOENT)
  97                                         ret = -errno;
  98                                 continue;
  99                         }
 100
 101                         /* Stop at mount points */
 102                         r = fd_is_mount_point(fd, de->d_name, 0);
 103                         if (r < 0) {
 104                                 if (ret == 0 && r != -ENOENT)
 105                                         ret = r;
 106
 107                                 continue;
 108                         }
 109                         if (r > 0)
 110                                 continue;
 111
 112                         if ((flags & REMOVE_SUBVOLUME) && st.st_ino == 256) {
 113
 114                                 /* This could be a subvolume, try to remove it */
 115
 116                                 r = btrfs_subvol_remove_fd(fd, de->d_name, BTRFS_REMOVE_RECURSIVE|BTRFS_REMOVE_QUOTA);
 117                                 if (r < 0) {
 118                                         if (!IN_SET(r, -ENOTTY, -EINVAL)) {
 119                                                 if (ret == 0)
 120                                                         ret = r;
 121
 122                                                 continue;
 123                                         }
 124
 125                                         /* ENOTTY, then it wasn't a btrfs subvolume, continue below. */
 126                                 } else
 127                                         /* It was a subvolume, continue. */
 128                                         continue;
 129                         }
 130
 131                         /* We pass REMOVE_PHYSICAL here, to avoid doing the fstatfs() to check the file
 132                          * system type again for each directory */
 133                         r = rm_rf_children(TAKE_FD(subdir_fd), flags | REMOVE_PHYSICAL, root_dev);
 134                         if (r < 0 && ret == 0)
 135                                 ret = r;
 136
 137                         if (unlinkat(fd, de->d_name, AT_REMOVEDIR) < 0) {
 138                                 if (ret == 0 && errno != ENOENT)
 139                                         ret = -errno;
 140                         }
 141
 142                 } else if (!(flags & REMOVE_ONLY_DIRECTORIES)) {
 143
 144                         if (unlinkat(fd, de->d_name, 0) < 0) {
 145                                 if (ret == 0 && errno != ENOENT)
 146                                         ret = -errno;
 147                         }
 148                 }
 149         }
 150         return ret;
 151 }
 152
 153 int rm_rf(const char *path, RemoveFlags flags) {
 154         int fd, r;
 155         struct statfs s;
 156
 157         assert(path);
 158
 159         /* For now, don't support dropping subvols when also only dropping directories, since we can't do
 160          * this race-freely. */
 161         if (FLAGS_SET(flags, REMOVE_ONLY_DIRECTORIES|REMOVE_SUBVOLUME))
 162                 return -EINVAL;
 163
 164         /* We refuse to clean the root file system with this call. This is extra paranoia to never cause a
 165          * really seriously broken system. */
 166         if (path_equal_or_files_same(path, "/", AT_SYMLINK_NOFOLLOW))
 167                 return log_error_errno(SYNTHETIC_ERRNO(EPERM),
 168                                        "Attempted to remove entire root file system (\"%s\"), and we can't allow that.",
 169                                        path);
 170
 171         if (FLAGS_SET(flags, REMOVE_SUBVOLUME | REMOVE_ROOT | REMOVE_PHYSICAL)) {
 172                 /* Try to remove as subvolume first */
 173                 r = btrfs_subvol_remove(path, BTRFS_REMOVE_RECURSIVE|BTRFS_REMOVE_QUOTA);
 174                 if (r >= 0)
 175                         return r;
 176
 177                 if (FLAGS_SET(flags, REMOVE_MISSING_OK) && r == -ENOENT)
 178                         return 0;
 179
 180                 if (!IN_SET(r, -ENOTTY, -EINVAL, -ENOTDIR))
 181                         return r;
 182
 183                 /* Not btrfs or not a subvolume */
 184         }
 185
 186         fd = open(path, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
 187         if (fd < 0) {
 188                 if (FLAGS_SET(flags, REMOVE_MISSING_OK) && errno == ENOENT)
 189                         return 0;
 190
 191                 if (!IN_SET(errno, ENOTDIR, ELOOP))
 192                         return -errno;
 193
 194                 if (FLAGS_SET(flags, REMOVE_ONLY_DIRECTORIES))
 195                         return 0;
 196
 197                 if (FLAGS_SET(flags, REMOVE_ROOT)) {
 198
 199                         if (!FLAGS_SET(flags, REMOVE_PHYSICAL)) {
 200                                 if (statfs(path, &s) < 0)
 201                                         return -errno;
 202
 203                                 if (is_physical_fs(&s))
 204                                         return log_error_errno(SYNTHETIC_ERRNO(EPERM),
 205                                                                "Attempted to remove files from a disk file system under \"%s\", refusing.",
 206                                                                path);
 207                         }
 208
 209                         if (unlink(path) < 0) {
 210                                 if (FLAGS_SET(flags, REMOVE_MISSING_OK) && errno == ENOENT)
 211                                         return 0;
 212
 213                                 return -errno;
 214                         }
 215                 }
 216
 217                 return 0;
 218         }
 219
 220         r = rm_rf_children(fd, flags, NULL);
 221
 222         if (FLAGS_SET(flags, REMOVE_ROOT) &&
 223             rmdir(path) < 0 &&
 224             r >= 0 &&
 225             (!FLAGS_SET(flags, REMOVE_MISSING_OK) || errno != ENOENT))
 226                 r = -errno;
 227
 228         return r;
 229 }