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>
- fscrypt framework usage updates
- One huge fix for xattr unlink
- Cleanup of fscrypt ifdefs
- Fix for our new UBIFS auth feature
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Merge tag 'upstream-5.2-rc1' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/rw/ubifs
Pull UBI/UBIFS updates from Richard Weinberger:
- fscrypt framework usage updates
- One huge fix for xattr unlink
- Cleanup of fscrypt ifdefs
- Fix for our new UBIFS auth feature
* tag 'upstream-5.2-rc1' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/rw/ubifs:
ubi: wl: Fix uninitialized variable
ubifs: Drop unnecessary setting of zbr->znode
ubifs: Remove ifdefs around CONFIG_UBIFS_ATIME_SUPPORT
ubifs: Remove #ifdef around CONFIG_FS_ENCRYPTION
ubifs: Limit number of xattrs per inode
ubifs: orphan: Handle xattrs like files
ubifs: journal: Handle xattrs like files
ubifs: find.c: replace swap function with built-in one
ubifs: Do not skip hash checking in data nodes
ubifs: work around high stack usage with clang
ubifs: remove unused function __ubifs_shash_final
ubifs: remove unnecessary #ifdef around fscrypt_ioctl_get_policy()
ubifs: remove unnecessary calls to set up directory key
Building this file with clang can result in large stack usage as seen from
this warning:
fs/ubifs/auth.c:78:5: error: stack frame size of 1152 bytes in function 'ubifs_prepare_auth_node'
The problem is that inlining ubifs_hash_calc_hmac() leads to
two SHASH_DESC_ON_STACK() blocks in the same function, and clang
for some reason does not reuse the stack space as it should.
Putting the first declaration into a separate basic block avoids
this problem and reduces the stack allocation to 640 bytes.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
There is no callers in tree, and can be removed.
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: Richard Weinberger <richard@nod.at>
The flags field in 'struct shash_desc' never actually does anything.
The only ostensibly supported flag is CRYPTO_TFM_REQ_MAY_SLEEP.
However, no shash algorithm ever sleeps, making this flag a no-op.
With this being the case, inevitably some users who can't sleep wrongly
pass MAY_SLEEP. These would all need to be fixed if any shash algorithm
actually started sleeping. For example, the shash_ahash_*() functions,
which wrap a shash algorithm with the ahash API, pass through MAY_SLEEP
from the ahash API to the shash API. However, the shash functions are
called under kmap_atomic(), so actually they're assumed to never sleep.
Even if it turns out that some users do need preemption points while
hashing large buffers, we could easily provide a helper function
crypto_shash_update_large() which divides the data into smaller chunks
and calls crypto_shash_update() and cond_resched() for each chunk. It's
not necessary to have a flag in 'struct shash_desc', nor is it necessary
to make individual shash algorithms aware of this at all.
Therefore, remove shash_desc::flags, and document that the
crypto_shash_*() functions can be called from any context.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
'shash' algorithms are always synchronous, so passing CRYPTO_ALG_ASYNC
in the mask to crypto_alloc_shash() has no effect. Many users therefore
already don't pass it, but some still do. This inconsistency can cause
confusion, especially since the way the 'mask' argument works is
somewhat counterintuitive.
Thus, just remove the unneeded CRYPTO_ALG_ASYNC flags.
This patch shouldn't change any actual behavior.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch adds the various helper functions needed for authentication
support. We need functions to hash nodes, to embed HMACs into a node and
to compare hashes and HMACs. Most functions first check if this
filesystem is authenticated and bail out early if not, which makes the
functions safe to be called with disabled authentication.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Richard Weinberger <richard@nod.at>
