src/basic/chattr-util.h

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2 #pragma once
   3
   4 #include <fcntl.h>
   5 #include <linux/fs.h>
   6 #include <stdbool.h>
   7 #include <stddef.h>
   8
   9 #include "missing_fs.h"
  10
  11 /* The chattr() flags to apply when creating a new file *before* writing to it. In particular, flags such as
  12  * FS_NOCOW_FL don't work if applied a-posteriori. All other flags are fine (or even necessary, think
  13  * FS_IMMUTABLE_FL!) to apply after writing to the files. */
  14 #define CHATTR_EARLY_FL                         \
  15         (FS_NOATIME_FL |                        \
  16          FS_COMPR_FL   |                        \
  17          FS_NOCOW_FL   |                        \
  18          FS_NOCOMP_FL  |                        \
  19          FS_PROJINHERIT_FL)
  20
  21 #define CHATTR_ALL_FL                           \
  22         (FS_NOATIME_FL      |                   \
  23          FS_SYNC_FL         |                   \
  24          FS_DIRSYNC_FL      |                   \
  25          FS_APPEND_FL       |                   \
  26          FS_COMPR_FL        |                   \
  27          FS_NODUMP_FL       |                   \
  28          FS_EXTENT_FL       |                   \
  29          FS_IMMUTABLE_FL    |                   \
  30          FS_JOURNAL_DATA_FL |                   \
  31          FS_SECRM_FL        |                   \
  32          FS_UNRM_FL         |                   \
  33          FS_NOTAIL_FL       |                   \
  34          FS_TOPDIR_FL       |                   \
  35          FS_NOCOW_FL        |                   \
  36          FS_PROJINHERIT_FL)
  37
  38 typedef enum ChattrApplyFlags {
  39         CHATTR_FALLBACK_BITWISE       = 1 << 0,
  40         CHATTR_WARN_UNSUPPORTED_FLAGS = 1 << 1,
  41 } ChattrApplyFlags;
  42
  43 int chattr_full(int dir_fd, const char *path, unsigned value, unsigned mask, unsigned *ret_previous, unsigned *ret_final, ChattrApplyFlags flags);
  44 static inline int chattr_at(int dir_fd, const char *path, unsigned value, unsigned mask, unsigned *previous) {
  45         return chattr_full(dir_fd, path, value, mask, previous, NULL, 0);
  46 }
  47 static inline int chattr_fd(int fd, unsigned value, unsigned mask, unsigned *previous) {
  48         return chattr_full(fd, NULL, value, mask, previous, NULL, 0);
  49 }
  50 static inline int chattr_path(const char *path, unsigned value, unsigned mask, unsigned *previous) {
  51         return chattr_full(AT_FDCWD, path, value, mask, previous, NULL, 0);
  52 }
  53
  54 int read_attr_fd(int fd, unsigned *ret);
  55 int read_attr_at(int dir_fd, const char *path, unsigned *ret);
  56
  57 /* Combination of chattr flags, that should be appropriate for secrets stored on disk: Secure Remove +
  58  * Exclusion from Dumping + Synchronous Writing (i.e. not caching in memory) + In-Place Updating (i.e. not
  59  * spurious copies). */
  60 #define CHATTR_SECRET_FLAGS (FS_SECRM_FL|FS_NODUMP_FL|FS_SYNC_FL|FS_NOCOW_FL)
  61
  62 static inline int chattr_secret(int fd, ChattrApplyFlags flags) {
  63         return chattr_full(fd, NULL, CHATTR_SECRET_FLAGS, CHATTR_SECRET_FLAGS, NULL, NULL, flags|CHATTR_FALLBACK_BITWISE);
  64 }