src/basic/rm-rf.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   Copyright 2015 Lennart Poettering
   4 ***/
   5
   6 #include <errno.h>
   7 #include <fcntl.h>
   8 #include <stdbool.h>
   9 #include <stddef.h>
  10 #include <sys/stat.h>
  11 #include <sys/statfs.h>
  12 #include <unistd.h>
  13
  14 //#include "alloc-util.h"
  15 //#include "btrfs-util.h"
  16 #include "cgroup-util.h"
  17 #include "dirent-util.h"
  18 #include "fd-util.h"
  19 #include "log.h"
  20 #include "macro.h"
  21 #include "mount-util.h"
  22 #include "path-util.h"
  23 #include "rm-rf.h"
  24 #include "stat-util.h"
  25 #include "string-util.h"
  26
  27 static bool is_physical_fs(const struct statfs *sfs) {
  28         return !is_temporary_fs(sfs) && !is_cgroup_fs(sfs);
  29 }
  30
  31 int rm_rf_children(int fd, RemoveFlags flags, struct stat *root_dev) {
  32         _cleanup_closedir_ DIR *d = NULL;
  33         struct dirent *de;
  34         int ret = 0, r;
  35         struct statfs sfs;
  36
  37         assert(fd >= 0);
  38
  39         /* This returns the first error we run into, but nevertheless
  40          * tries to go on. This closes the passed fd. */
  41
  42         if (!(flags & REMOVE_PHYSICAL)) {
  43
  44                 r = fstatfs(fd, &sfs);
  45                 if (r < 0) {
  46                         safe_close(fd);
  47                         return -errno;
  48                 }
  49
  50                 if (is_physical_fs(&sfs)) {
  51                         /* We refuse to clean physical file systems with this call,
  52                          * unless explicitly requested. This is extra paranoia just
  53                          * to be sure we never ever remove non-state data. */
  54                         _cleanup_free_ char *path = NULL;
  55
  56                         (void) fd_get_path(fd, &path);
  57                         log_error("Attempted to remove disk file system under \"%s\", and we can't allow that.",
  58                                   strna(path));
  59
  60                         safe_close(fd);
  61                         return -EPERM;
  62                 }
  63         }
  64
  65         d = fdopendir(fd);
  66         if (!d) {
  67                 safe_close(fd);
  68                 return errno == ENOENT ? 0 : -errno;
  69         }
  70
  71         FOREACH_DIRENT_ALL(de, d, return -errno) {
  72                 bool is_dir;
  73                 struct stat st;
  74
  75                 if (dot_or_dot_dot(de->d_name))
  76                         continue;
  77
  78                 if (de->d_type == DT_UNKNOWN ||
  79                     (de->d_type == DT_DIR && (root_dev || (flags & REMOVE_SUBVOLUME)))) {
  80                         if (fstatat(fd, de->d_name, &st, AT_SYMLINK_NOFOLLOW) < 0) {
  81                                 if (ret == 0 && errno != ENOENT)
  82                                         ret = -errno;
  83                                 continue;
  84                         }
  85
  86                         is_dir = S_ISDIR(st.st_mode);
  87                 } else
  88                         is_dir = de->d_type == DT_DIR;
  89
  90                 if (is_dir) {
  91                         int subdir_fd;
  92
  93                         /* if root_dev is set, remove subdirectories only if device is same */
  94                         if (root_dev && st.st_dev != root_dev->st_dev)
  95                                 continue;
  96
  97                         subdir_fd = openat(fd, de->d_name, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
  98                         if (subdir_fd < 0) {
  99                                 if (ret == 0 && errno != ENOENT)
 100                                         ret = -errno;
 101                                 continue;
 102                         }
 103
 104                         /* Stop at mount points */
 105                         r = fd_is_mount_point(fd, de->d_name, 0);
 106                         if (r < 0) {
 107                                 if (ret == 0 && r != -ENOENT)
 108                                         ret = r;
 109
 110                                 safe_close(subdir_fd);
 111                                 continue;
 112                         }
 113                         if (r) {
 114                                 safe_close(subdir_fd);
 115                                 continue;
 116                         }
 117
 118 #if 0 /// elogind does not support BTRFS this directly
 119                         if ((flags & REMOVE_SUBVOLUME) && st.st_ino == 256) {
 120
 121                                 /* This could be a subvolume, try to remove it */
 122
 123                                 r = btrfs_subvol_remove_fd(fd, de->d_name, BTRFS_REMOVE_RECURSIVE|BTRFS_REMOVE_QUOTA);
 124                                 if (r < 0) {
 125                                         if (!IN_SET(r, -ENOTTY, -EINVAL)) {
 126                                                 if (ret == 0)
 127                                                         ret = r;
 128
 129                                                 safe_close(subdir_fd);
 130                                                 continue;
 131                                         }
 132
 133                                         /* ENOTTY, then it wasn't a
 134                                          * btrfs subvolume, continue
 135                                          * below. */
 136                                 } else {
 137                                         /* It was a subvolume, continue. */
 138                                         safe_close(subdir_fd);
 139                                         continue;
 140                                 }
 141                         }
 142 #endif // 0
 143
 144                         /* We pass REMOVE_PHYSICAL here, to avoid
 145                          * doing the fstatfs() to check the file
 146                          * system type again for each directory */
 147                         r = rm_rf_children(subdir_fd, flags | REMOVE_PHYSICAL, root_dev);
 148                         if (r < 0 && ret == 0)
 149                                 ret = r;
 150
 151                         if (unlinkat(fd, de->d_name, AT_REMOVEDIR) < 0) {
 152                                 if (ret == 0 && errno != ENOENT)
 153                                         ret = -errno;
 154                         }
 155
 156                 } else if (!(flags & REMOVE_ONLY_DIRECTORIES)) {
 157
 158                         if (unlinkat(fd, de->d_name, 0) < 0) {
 159                                 if (ret == 0 && errno != ENOENT)
 160                                         ret = -errno;
 161                         }
 162                 }
 163         }
 164         return ret;
 165 }
 166
 167 int rm_rf(const char *path, RemoveFlags flags) {
 168         int fd, r;
 169         struct statfs s;
 170
 171         assert(path);
 172
 173         /* We refuse to clean the root file system with this
 174          * call. This is extra paranoia to never cause a really
 175          * seriously broken system. */
 176         if (path_equal_or_files_same(path, "/", AT_SYMLINK_NOFOLLOW)) {
 177                 log_error("Attempted to remove entire root file system (\"%s\"), and we can't allow that.", path);
 178                 return -EPERM;
 179         }
 180
 181 #if 0 /// elogind does not support BTRFS this directly
 182         if (FLAGS_SET(flags, REMOVE_SUBVOLUME | REMOVE_ROOT | REMOVE_PHYSICAL)) {
 183                 /* Try to remove as subvolume first */
 184                 r = btrfs_subvol_remove(path, BTRFS_REMOVE_RECURSIVE|BTRFS_REMOVE_QUOTA);
 185                 if (r >= 0)
 186                         return r;
 187
 188                 if (!IN_SET(r, -ENOTTY, -EINVAL, -ENOTDIR))
 189                         return r;
 190
 191                 /* Not btrfs or not a subvolume */
 192         }
 193 #endif // 0
 194
 195         fd = open(path, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
 196         if (fd < 0) {
 197                 if (!IN_SET(errno, ENOTDIR, ELOOP))
 198                         return -errno;
 199
 200                 if (!(flags & REMOVE_PHYSICAL)) {
 201                         if (statfs(path, &s) < 0)
 202                                 return -errno;
 203
 204                         if (is_physical_fs(&s)) {
 205                                 log_error("Attempted to remove files from a disk file system under \"%s\", refusing.", path);
 206                                 return -EPERM;
 207                         }
 208                 }
 209
 210                 if ((flags & REMOVE_ROOT) && !(flags & REMOVE_ONLY_DIRECTORIES))
 211                         if (unlink(path) < 0 && errno != ENOENT)
 212                                 return -errno;
 213
 214                 return 0;
 215         }
 216
 217         r = rm_rf_children(fd, flags, NULL);
 218
 219         if (flags & REMOVE_ROOT) {
 220                 if (rmdir(path) < 0) {
 221                         if (r == 0 && errno != ENOENT)
 222                                 r = -errno;
 223                 }
 224         }
 225
 226         return r;
 227 }