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