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| author | Sascha Hauer <s.hauer@pengutronix.de> | 2019-05-14 10:33:22 +0200 |
|---|---|---|
| committer | Richard Weinberger <richard@nod.at> | 2019-07-08 19:43:52 +0200 |
| commit | 817aa094842dfc3a6b98c9582d4a647827f66201 (patch) | |
| tree | 68919bfade27218cdb9e66c8bcaa2f2aa32b685e /fs/ubifs/ubifs.h | |
| parent | 8ba0a2ab84b23b541a5d2ef25d759c94880e7457 (diff) | |
| download | linux-817aa094842dfc3a6b98c9582d4a647827f66201.tar.gz linux-817aa094842dfc3a6b98c9582d4a647827f66201.tar.bz2 linux-817aa094842dfc3a6b98c9582d4a647827f66201.zip | |
ubifs: support offline signed images
HMACs can only be generated on the system the UBIFS image is running on.
To support offline signed images we add a PKCS#7 signature to the UBIFS
image which can be created by mkfs.ubifs.
Both the master node and the superblock need to be authenticated, during
normal runtime both are protected with HMACs. For offline signature
support however only a single signature is desired. We add a signature
covering the superblock node directly behind it. To protect the master
node a hash of the master node is added to the superblock which is used
when the master node doesn't contain a HMAC.
Transition to a read/write filesystem is also supported. During
transition first the master node is rewritten with a HMAC (implicitly,
it is written anyway as the FS is marked dirty). Afterwards the
superblock is rewritten with a HMAC. Once after the image has been
mounted read/write it is HMAC only, the signature is no longer required
or even present on the filesystem.
In an offline signed image the master node is authenticated by the
superblock. In a transition to r/w we have to make sure that the master
node is rewritten before the superblock node. In this case the master
node gets a HMAC and its authenticity no longer depends on the
superblock node. There are some cases in which the current code first
writes the superblock node though, so with this patch writing of the
superblock node is delayed until the master node is written.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Richard Weinberger <richard@nod.at>
Diffstat (limited to 'fs/ubifs/ubifs.h')
| -rw-r--r-- | fs/ubifs/ubifs.h | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h index 745b23e5b406..c55f212dcb75 100644 --- a/fs/ubifs/ubifs.h +++ b/fs/ubifs/ubifs.h @@ -1104,7 +1104,6 @@ struct ubifs_debug_info; * used to store indexing nodes (@leb_size - @max_idx_node_sz) * @leb_cnt: count of logical eraseblocks * @max_leb_cnt: maximum count of logical eraseblocks - * @old_leb_cnt: count of logical eraseblocks before re-size * @ro_media: the underlying UBI volume is read-only * @ro_mount: the file-system was mounted as read-only * @ro_error: UBIFS switched to R/O mode because an error happened @@ -1295,6 +1294,7 @@ struct ubifs_info { unsigned int rw_incompat:1; unsigned int assert_action:2; unsigned int authenticated:1; + unsigned int superblock_need_write:1; struct mutex tnc_mutex; struct ubifs_zbranch zroot; @@ -1352,7 +1352,6 @@ struct ubifs_info { int idx_leb_size; int leb_cnt; int max_leb_cnt; - int old_leb_cnt; unsigned int ro_media:1; unsigned int ro_mount:1; unsigned int ro_error:1; @@ -1680,6 +1679,9 @@ static inline int ubifs_auth_node_sz(const struct ubifs_info *c) else return 0; } +int ubifs_sb_verify_signature(struct ubifs_info *c, + const struct ubifs_sb_node *sup); +bool ubifs_hmac_zero(struct ubifs_info *c, const u8 *hmac); int ubifs_hmac_wkm(struct ubifs_info *c, u8 *hmac); |