src/basic/rm-rf.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2015 Lennart Poettering
   6 ***/
   7
   8 #include <errno.h>
   9 #include <fcntl.h>
  10 #include <stdbool.h>
  11 #include <stddef.h>
  12 #include <sys/stat.h>
  13 #include <sys/statfs.h>
  14 #include <unistd.h>
  15
  16 #include "btrfs-util.h"
  17 #include "cgroup-util.h"
  18 #include "dirent-util.h"
  19 #include "fd-util.h"
  20 #include "log.h"
  21 #include "macro.h"
  22 #include "mount-util.h"
  23 #include "path-util.h"
  24 #include "rm-rf.h"
  25 #include "stat-util.h"
  26 #include "string-util.h"
  27
  28 static bool is_physical_fs(const struct statfs *sfs) {
  29         return !is_temporary_fs(sfs) && !is_cgroup_fs(sfs);
  30 }
  31
  32 int rm_rf_children(int fd, RemoveFlags flags, struct stat *root_dev) {
  33         _cleanup_closedir_ DIR *d = NULL;
  34         struct dirent *de;
  35         int ret = 0, r;
  36         struct statfs sfs;
  37
  38         assert(fd >= 0);
  39
  40         /* This returns the first error we run into, but nevertheless
  41          * tries to go on. This closes the passed fd. */
  42
  43         if (!(flags & REMOVE_PHYSICAL)) {
  44
  45                 r = fstatfs(fd, &sfs);
  46                 if (r < 0) {
  47                         safe_close(fd);
  48                         return -errno;
  49                 }
  50
  51                 if (is_physical_fs(&sfs)) {
  52                         /* We refuse to clean physical file systems
  53                          * with this call, unless explicitly
  54                          * requested. This is extra paranoia just to
  55                          * be sure we never ever remove non-state
  56                          * data */
  57
  58                         log_error("Attempted to remove disk file system, and we can't allow that.");
  59                         safe_close(fd);
  60                         return -EPERM;
  61                 }
  62         }
  63
  64         d = fdopendir(fd);
  65         if (!d) {
  66                 safe_close(fd);
  67                 return errno == ENOENT ? 0 : -errno;
  68         }
  69
  70         FOREACH_DIRENT_ALL(de, d, return -errno) {
  71                 bool is_dir;
  72                 struct stat st;
  73
  74                 if (dot_or_dot_dot(de->d_name))
  75                         continue;
  76
  77                 if (de->d_type == DT_UNKNOWN ||
  78                     (de->d_type == DT_DIR && (root_dev || (flags & REMOVE_SUBVOLUME)))) {
  79                         if (fstatat(fd, de->d_name, &st, AT_SYMLINK_NOFOLLOW) < 0) {
  80                                 if (ret == 0 && errno != ENOENT)
  81                                         ret = -errno;
  82                                 continue;
  83                         }
  84
  85                         is_dir = S_ISDIR(st.st_mode);
  86                 } else
  87                         is_dir = de->d_type == DT_DIR;
  88
  89                 if (is_dir) {
  90                         int subdir_fd;
  91
  92                         /* if root_dev is set, remove subdirectories only if device is same */
  93                         if (root_dev && st.st_dev != root_dev->st_dev)
  94                                 continue;
  95
  96                         subdir_fd = openat(fd, de->d_name, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
  97                         if (subdir_fd < 0) {
  98                                 if (ret == 0 && errno != ENOENT)
  99                                         ret = -errno;
 100                                 continue;
 101                         }
 102
 103                         /* Stop at mount points */
 104                         r = fd_is_mount_point(fd, de->d_name, 0);
 105                         if (r < 0) {
 106                                 if (ret == 0 && r != -ENOENT)
 107                                         ret = r;
 108
 109                                 safe_close(subdir_fd);
 110                                 continue;
 111                         }
 112                         if (r) {
 113                                 safe_close(subdir_fd);
 114                                 continue;
 115                         }
 116
 117                         if ((flags & REMOVE_SUBVOLUME) && st.st_ino == 256) {
 118
 119                                 /* This could be a subvolume, try to remove it */
 120
 121                                 r = btrfs_subvol_remove_fd(fd, de->d_name, BTRFS_REMOVE_RECURSIVE|BTRFS_REMOVE_QUOTA);
 122                                 if (r < 0) {
 123                                         if (!IN_SET(r, -ENOTTY, -EINVAL)) {
 124                                                 if (ret == 0)
 125                                                         ret = r;
 126
 127                                                 safe_close(subdir_fd);
 128                                                 continue;
 129                                         }
 130
 131                                         /* ENOTTY, then it wasn't a
 132                                          * btrfs subvolume, continue
 133                                          * below. */
 134                                 } else {
 135                                         /* It was a subvolume, continue. */
 136                                         safe_close(subdir_fd);
 137                                         continue;
 138                                 }
 139                         }
 140
 141                         /* We pass REMOVE_PHYSICAL here, to avoid
 142                          * doing the fstatfs() to check the file
 143                          * system type again for each directory */
 144                         r = rm_rf_children(subdir_fd, flags | REMOVE_PHYSICAL, root_dev);
 145                         if (r < 0 && ret == 0)
 146                                 ret = r;
 147
 148                         if (unlinkat(fd, de->d_name, AT_REMOVEDIR) < 0) {
 149                                 if (ret == 0 && errno != ENOENT)
 150                                         ret = -errno;
 151                         }
 152
 153                 } else if (!(flags & REMOVE_ONLY_DIRECTORIES)) {
 154
 155                         if (unlinkat(fd, de->d_name, 0) < 0) {
 156                                 if (ret == 0 && errno != ENOENT)
 157                                         ret = -errno;
 158                         }
 159                 }
 160         }
 161         return ret;
 162 }
 163
 164 int rm_rf(const char *path, RemoveFlags flags) {
 165         int fd, r;
 166         struct statfs s;
 167
 168         assert(path);
 169
 170         /* We refuse to clean the root file system with this
 171          * call. This is extra paranoia to never cause a really
 172          * seriously broken system. */
 173         if (path_equal_or_files_same(path, "/", AT_SYMLINK_NOFOLLOW)) {
 174                 log_error("Attempted to remove entire root file system, and we can't allow that.");
 175                 return -EPERM;
 176         }
 177
 178         if ((flags & (REMOVE_SUBVOLUME|REMOVE_ROOT|REMOVE_PHYSICAL)) == (REMOVE_SUBVOLUME|REMOVE_ROOT|REMOVE_PHYSICAL)) {
 179                 /* Try to remove as subvolume first */
 180                 r = btrfs_subvol_remove(path, BTRFS_REMOVE_RECURSIVE|BTRFS_REMOVE_QUOTA);
 181                 if (r >= 0)
 182                         return r;
 183
 184                 if (!IN_SET(r, -ENOTTY, -EINVAL, -ENOTDIR))
 185                         return r;
 186
 187                 /* Not btrfs or not a subvolume */
 188         }
 189
 190         fd = open(path, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
 191         if (fd < 0) {
 192
 193                 if (!IN_SET(errno, ENOTDIR, ELOOP))
 194                         return -errno;
 195
 196                 if (!(flags & REMOVE_PHYSICAL)) {
 197                         if (statfs(path, &s) < 0)
 198                                 return -errno;
 199
 200                         if (is_physical_fs(&s)) {
 201                                 log_error("Attempted to remove disk file system, and we can't allow that.");
 202                                 return -EPERM;
 203                         }
 204                 }
 205
 206                 if ((flags & REMOVE_ROOT) && !(flags & REMOVE_ONLY_DIRECTORIES))
 207                         if (unlink(path) < 0 && errno != ENOENT)
 208                                 return -errno;
 209
 210                 return 0;
 211         }
 212
 213         r = rm_rf_children(fd, flags, NULL);
 214
 215         if (flags & REMOVE_ROOT) {
 216                 if (rmdir(path) < 0) {
 217                         if (r == 0 && errno != ENOENT)
 218                                 r = -errno;
 219                 }
 220         }
 221
 222         return r;
 223 }