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 "mount-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
  37          * tries to go on. This closes the passed fd. */
  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                         int subdir_fd;
  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                                 safe_close(subdir_fd);
 108                                 continue;
 109                         }
 110                         if (r) {
 111                                 safe_close(subdir_fd);
 112                                 continue;
 113                         }
 114
 115                         if ((flags & REMOVE_SUBVOLUME) && st.st_ino == 256) {
 116
 117                                 /* This could be a subvolume, try to remove it */
 118
 119                                 r = btrfs_subvol_remove_fd(fd, de->d_name, BTRFS_REMOVE_RECURSIVE|BTRFS_REMOVE_QUOTA);
 120                                 if (r < 0) {
 121                                         if (!IN_SET(r, -ENOTTY, -EINVAL)) {
 122                                                 if (ret == 0)
 123                                                         ret = r;
 124
 125                                                 safe_close(subdir_fd);
 126                                                 continue;
 127                                         }
 128
 129                                         /* ENOTTY, then it wasn't a
 130                                          * btrfs subvolume, continue
 131                                          * below. */
 132                                 } else {
 133                                         /* It was a subvolume, continue. */
 134                                         safe_close(subdir_fd);
 135                                         continue;
 136                                 }
 137                         }
 138
 139                         /* We pass REMOVE_PHYSICAL here, to avoid
 140                          * doing the fstatfs() to check the file
 141                          * system type again for each directory */
 142                         r = rm_rf_children(subdir_fd, flags | REMOVE_PHYSICAL, root_dev);
 143                         if (r < 0 && ret == 0)
 144                                 ret = r;
 145
 146                         if (unlinkat(fd, de->d_name, AT_REMOVEDIR) < 0) {
 147                                 if (ret == 0 && errno != ENOENT)
 148                                         ret = -errno;
 149                         }
 150
 151                 } else if (!(flags & REMOVE_ONLY_DIRECTORIES)) {
 152
 153                         if (unlinkat(fd, de->d_name, 0) < 0) {
 154                                 if (ret == 0 && errno != ENOENT)
 155                                         ret = -errno;
 156                         }
 157                 }
 158         }
 159         return ret;
 160 }
 161
 162 int rm_rf(const char *path, RemoveFlags flags) {
 163         int fd, r;
 164         struct statfs s;
 165
 166         assert(path);
 167
 168         /* We refuse to clean the root file system with this
 169          * call. This is extra paranoia to never cause a really
 170          * seriously broken system. */
 171         if (path_equal_or_files_same(path, "/", AT_SYMLINK_NOFOLLOW)) {
 172                 log_error("Attempted to remove entire root file system (\"%s\"), and we can't allow that.", path);
 173                 return -EPERM;
 174         }
 175
 176         if (FLAGS_SET(flags, REMOVE_SUBVOLUME | REMOVE_ROOT | REMOVE_PHYSICAL)) {
 177                 /* Try to remove as subvolume first */
 178                 r = btrfs_subvol_remove(path, BTRFS_REMOVE_RECURSIVE|BTRFS_REMOVE_QUOTA);
 179                 if (r >= 0)
 180                         return r;
 181
 182                 if (!IN_SET(r, -ENOTTY, -EINVAL, -ENOTDIR))
 183                         return r;
 184
 185                 /* Not btrfs or not a subvolume */
 186         }
 187
 188         fd = open(path, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
 189         if (fd < 0) {
 190                 if (!IN_SET(errno, ENOTDIR, ELOOP))
 191                         return -errno;
 192
 193                 if (!(flags & REMOVE_PHYSICAL)) {
 194                         if (statfs(path, &s) < 0)
 195                                 return -errno;
 196
 197                         if (is_physical_fs(&s)) {
 198                                 log_error("Attempted to remove files from a disk file system under \"%s\", refusing.", path);
 199                                 return -EPERM;
 200                         }
 201                 }
 202
 203                 if ((flags & REMOVE_ROOT) && !(flags & REMOVE_ONLY_DIRECTORIES))
 204                         if (unlink(path) < 0 && errno != ENOENT)
 205                                 return -errno;
 206
 207                 return 0;
 208         }
 209
 210         r = rm_rf_children(fd, flags, NULL);
 211
 212         if (flags & REMOVE_ROOT) {
 213                 if (rmdir(path) < 0) {
 214                         if (r == 0 && errno != ENOENT)
 215                                 r = -errno;
 216                 }
 217         }
 218
 219         return r;
 220 }