src/basic/rm-rf.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2015 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <stdbool.h>
  23 #include <stddef.h>
  24 #include <sys/stat.h>
  25 #include <sys/statfs.h>
  26 #include <unistd.h>
  27
  28 #include "btrfs-util.h"
  29 #include "cgroup-util.h"
  30 #include "dirent-util.h"
  31 #include "fd-util.h"
  32 #include "log.h"
  33 #include "macro.h"
  34 #include "mount-util.h"
  35 #include "path-util.h"
  36 #include "rm-rf.h"
  37 #include "stat-util.h"
  38 #include "string-util.h"
  39
  40 static bool is_physical_fs(const struct statfs *sfs) {
  41         return !is_temporary_fs(sfs) && !is_cgroup_fs(sfs);
  42 }
  43
  44 int rm_rf_children(int fd, RemoveFlags flags, struct stat *root_dev) {
  45         _cleanup_closedir_ DIR *d = NULL;
  46         struct dirent *de;
  47         int ret = 0, r;
  48         struct statfs sfs;
  49
  50         assert(fd >= 0);
  51
  52         /* This returns the first error we run into, but nevertheless
  53          * tries to go on. This closes the passed fd. */
  54
  55         if (!(flags & REMOVE_PHYSICAL)) {
  56
  57                 r = fstatfs(fd, &sfs);
  58                 if (r < 0) {
  59                         safe_close(fd);
  60                         return -errno;
  61                 }
  62
  63                 if (is_physical_fs(&sfs)) {
  64                         /* We refuse to clean physical file systems
  65                          * with this call, unless explicitly
  66                          * requested. This is extra paranoia just to
  67                          * be sure we never ever remove non-state
  68                          * data */
  69
  70                         log_error("Attempted to remove disk file system, and we can't allow that.");
  71                         safe_close(fd);
  72                         return -EPERM;
  73                 }
  74         }
  75
  76         d = fdopendir(fd);
  77         if (!d) {
  78                 safe_close(fd);
  79                 return errno == ENOENT ? 0 : -errno;
  80         }
  81
  82         FOREACH_DIRENT_ALL(de, d, return -errno) {
  83                 bool is_dir;
  84                 struct stat st;
  85
  86                 if (dot_or_dot_dot(de->d_name))
  87                         continue;
  88
  89                 if (de->d_type == DT_UNKNOWN ||
  90                     (de->d_type == DT_DIR && (root_dev || (flags & REMOVE_SUBVOLUME)))) {
  91                         if (fstatat(fd, de->d_name, &st, AT_SYMLINK_NOFOLLOW) < 0) {
  92                                 if (ret == 0 && errno != ENOENT)
  93                                         ret = -errno;
  94                                 continue;
  95                         }
  96
  97                         is_dir = S_ISDIR(st.st_mode);
  98                 } else
  99                         is_dir = de->d_type == DT_DIR;
 100
 101                 if (is_dir) {
 102                         int subdir_fd;
 103
 104                         /* if root_dev is set, remove subdirectories only if device is same */
 105                         if (root_dev && st.st_dev != root_dev->st_dev)
 106                                 continue;
 107
 108                         subdir_fd = openat(fd, de->d_name, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
 109                         if (subdir_fd < 0) {
 110                                 if (ret == 0 && errno != ENOENT)
 111                                         ret = -errno;
 112                                 continue;
 113                         }
 114
 115                         /* Stop at mount points */
 116                         r = fd_is_mount_point(fd, de->d_name, 0);
 117                         if (r < 0) {
 118                                 if (ret == 0 && r != -ENOENT)
 119                                         ret = r;
 120
 121                                 safe_close(subdir_fd);
 122                                 continue;
 123                         }
 124                         if (r) {
 125                                 safe_close(subdir_fd);
 126                                 continue;
 127                         }
 128
 129                         if ((flags & REMOVE_SUBVOLUME) && st.st_ino == 256) {
 130
 131                                 /* This could be a subvolume, try to remove it */
 132
 133                                 r = btrfs_subvol_remove_fd(fd, de->d_name, BTRFS_REMOVE_RECURSIVE|BTRFS_REMOVE_QUOTA);
 134                                 if (r < 0) {
 135                                         if (r != -ENOTTY && r != -EINVAL) {
 136                                                 if (ret == 0)
 137                                                         ret = r;
 138
 139                                                 safe_close(subdir_fd);
 140                                                 continue;
 141                                         }
 142
 143                                         /* ENOTTY, then it wasn't a
 144                                          * btrfs subvolume, continue
 145                                          * below. */
 146                                 } else {
 147                                         /* It was a subvolume, continue. */
 148                                         safe_close(subdir_fd);
 149                                         continue;
 150                                 }
 151                         }
 152
 153                         /* We pass REMOVE_PHYSICAL here, to avoid
 154                          * doing the fstatfs() to check the file
 155                          * system type again for each directory */
 156                         r = rm_rf_children(subdir_fd, flags | REMOVE_PHYSICAL, root_dev);
 157                         if (r < 0 && ret == 0)
 158                                 ret = r;
 159
 160                         if (unlinkat(fd, de->d_name, AT_REMOVEDIR) < 0) {
 161                                 if (ret == 0 && errno != ENOENT)
 162                                         ret = -errno;
 163                         }
 164
 165                 } else if (!(flags & REMOVE_ONLY_DIRECTORIES)) {
 166
 167                         if (unlinkat(fd, de->d_name, 0) < 0) {
 168                                 if (ret == 0 && errno != ENOENT)
 169                                         ret = -errno;
 170                         }
 171                 }
 172         }
 173         return ret;
 174 }
 175
 176 int rm_rf(const char *path, RemoveFlags flags) {
 177         int fd, r;
 178         struct statfs s;
 179
 180         assert(path);
 181
 182         /* We refuse to clean the root file system with this
 183          * call. This is extra paranoia to never cause a really
 184          * seriously broken system. */
 185         if (path_equal_or_files_same(path, "/", AT_SYMLINK_NOFOLLOW)) {
 186                 log_error("Attempted to remove entire root file system, and we can't allow that.");
 187                 return -EPERM;
 188         }
 189
 190         if ((flags & (REMOVE_SUBVOLUME|REMOVE_ROOT|REMOVE_PHYSICAL)) == (REMOVE_SUBVOLUME|REMOVE_ROOT|REMOVE_PHYSICAL)) {
 191                 /* Try to remove as subvolume first */
 192                 r = btrfs_subvol_remove(path, BTRFS_REMOVE_RECURSIVE|BTRFS_REMOVE_QUOTA);
 193                 if (r >= 0)
 194                         return r;
 195
 196                 if (r != -ENOTTY && r != -EINVAL && r != -ENOTDIR)
 197                         return r;
 198
 199                 /* Not btrfs or not a subvolume */
 200         }
 201
 202         fd = open(path, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
 203         if (fd < 0) {
 204
 205                 if (!IN_SET(errno, ENOTDIR, ELOOP))
 206                         return -errno;
 207
 208                 if (!(flags & REMOVE_PHYSICAL)) {
 209                         if (statfs(path, &s) < 0)
 210                                 return -errno;
 211
 212                         if (is_physical_fs(&s)) {
 213                                 log_error("Attempted to remove disk file system, and we can't allow that.");
 214                                 return -EPERM;
 215                         }
 216                 }
 217
 218                 if ((flags & REMOVE_ROOT) && !(flags & REMOVE_ONLY_DIRECTORIES))
 219                         if (unlink(path) < 0 && errno != ENOENT)
 220                                 return -errno;
 221
 222                 return 0;
 223         }
 224
 225         r = rm_rf_children(fd, flags, NULL);
 226
 227         if (flags & REMOVE_ROOT) {
 228                 if (rmdir(path) < 0) {
 229                         if (r == 0 && errno != ENOENT)
 230                                 r = -errno;
 231                 }
 232         }
 233
 234         return r;
 235 }