linux-stable.git/crypto/ahash.c, branch linux-3.2.y

crypto: hash - prevent using keyed hashes without setting key

2018-05-31T23:30:07+00:00

commit 9fa68f620041be04720d0cbfb1bd3ddfc6310b24 upstream.

Currently, almost none of the keyed hash algorithms check whether a key
has been set before proceeding.  Some algorithms are okay with this and
will effectively just use a key of all 0's or some other bogus default.
However, others will severely break, as demonstrated using
"hmac(sha3-512-generic)", the unkeyed use of which causes a kernel crash
via a (potentially exploitable) stack buffer overflow.

A while ago, this problem was solved for AF_ALG by pairing each hash
transform with a 'has_key' bool.  However, there are still other places
in the kernel where userspace can specify an arbitrary hash algorithm by
name, and the kernel uses it as unkeyed hash without checking whether it
is really unkeyed.  Examples of this include:

    - KEYCTL_DH_COMPUTE, via the KDF extension
    - dm-verity
    - dm-crypt, via the ESSIV support
    - dm-integrity, via the "internal hash" mode with no key given
    - drbd (Distributed Replicated Block Device)

This bug is especially bad for KEYCTL_DH_COMPUTE as that requires no
privileges to call.

Fix the bug for all users by adding a flag CRYPTO_TFM_NEED_KEY to the
->crt_flags of each hash transform that indicates whether the transform
still needs to be keyed or not.  Then, make the hash init, import, and
digest functions return -ENOKEY if the key is still needed.

The new flag also replaces the 'has_key' bool which algif_hash was
previously using, thereby simplifying the algif_hash implementation.

Reported-by: syzbot 
Signed-off-by: Eric Biggers 
Signed-off-by: Herbert Xu 
[bwh: Backported to 3.2:
 - In hash_accept_parent_nokey(), update initialisation of ds to use tfm
 - Adjust context]
Signed-off-by: Ben Hutchings

crypto: hash - introduce crypto_hash_alg_has_setkey()

2018-05-31T23:30:07+00:00

commit cd6ed77ad5d223dc6299fb58f62e0f5267f7e2ba upstream.

Templates that use an shash spawn can use crypto_shash_alg_has_setkey()
to determine whether the underlying algorithm requires a key or not.
But there was no corresponding function for ahash spawns.  Add it.

Note that the new function actually has to support both shash and ahash
algorithms, since the ahash API can be used with either.

Signed-off-by: Eric Biggers 
Signed-off-by: Herbert Xu 
Signed-off-by: Ben Hutchings

crypto: ahash - Fix EINPROGRESS notification callback

2017-06-05T20:13:55+00:00

commit ef0579b64e93188710d48667cb5e014926af9f1b upstream.

The ahash API modifies the request's callback function in order
to clean up after itself in some corner cases (unaligned final
and missing finup).

When the request is complete ahash will restore the original
callback and everything is fine.  However, when the request gets
an EBUSY on a full queue, an EINPROGRESS callback is made while
the request is still ongoing.

In this case the ahash API will incorrectly call its own callback.

This patch fixes the problem by creating a temporary request
object on the stack which is used to relay EINPROGRESS back to
the original completion function.

This patch also adds code to preserve the original flags value.

Fixes: ab6bf4e5e5e4 ("crypto: hash - Fix the pointer voodoo in...")
Reported-by: Sabrina Dubroca 
Tested-by: Sabrina Dubroca 
Signed-off-by: Herbert Xu 
Signed-off-by: Ben Hutchings

crypto: hash - Simplify the ahash_finup implementation

2017-06-05T20:13:55+00:00

commit d4a7a0fbe959e12bdd071b79b50ed34853a6db8f upstream.

The ahash_def_finup() can make use of the request save/restore functions,
thus make it so. This simplifies the code a little and unifies the code
paths.

Note that the same remark about free()ing the req->priv applies here, the
req->priv can only be free()'d after the original request was restored.

Finally, squash a bug in the invocation of completion in the ASYNC path.
In both ahash_def_finup_done{1,2}, the function areq->base.complete(X, err);
was called with X=areq->base.data . This is incorrect , as X=&areq->base
is the correct value. By analysis of the data structures, we see the areq is
of type 'struct ahash_request' , areq->base is of type 'struct crypto_async_request'
and areq->base.completion is of type crypto_completion_t, which is defined in
include/linux/crypto.h as:

  typedef void (*crypto_completion_t)(struct crypto_async_request *req, int err);

This is one lead that the X should be &areq->base . Next up, we can inspect
other code which calls the completion callback to give us kind-of statistical
idea of how this callback is used. We can try:

  $ git grep base\.complete\( drivers/crypto/

Finally, by inspecting ahash_request_set_callback() implementation defined
in include/crypto/hash.h , we observe that the .data entry of 'struct
crypto_async_request' is intended for arbitrary data, not for completion
argument.

Signed-off-by: Marek Vasut 
Cc: David S. Miller 
Cc: Fabio Estevam 
Cc: Herbert Xu 
Cc: Shawn Guo 
Cc: Tom Lendacky 
Signed-off-by: Herbert Xu 
Signed-off-by: Ben Hutchings

crypto: hash - Pull out the functions to save/restore request

2017-06-05T20:13:55+00:00

commit 1ffc9fbd1e5071948b6d48f9a27d845738ee890f upstream.

The functions to save original request within a newly adjusted request
and it's counterpart to restore the original request can be re-used by
more code in the crypto/ahash.c file. Pull these functions out from the
code so they're available.

Signed-off-by: Marek Vasut 
Cc: David S. Miller 
Cc: Fabio Estevam 
Cc: Herbert Xu 
Cc: Shawn Guo 
Cc: Tom Lendacky 
Signed-off-by: Herbert Xu 
Signed-off-by: Ben Hutchings

crypto: hash - Fix the pointer voodoo in unaligned ahash

2017-06-05T20:13:55+00:00

commit ab6bf4e5e5e4298e8649e635bee25542cccbfd97 upstream.

Add documentation for the pointer voodoo that is happening in crypto/ahash.c
in ahash_op_unaligned(). This code is quite confusing, so add a beefy chunk
of documentation.

Moreover, make sure the mangled request is completely restored after finishing
this unaligned operation. This means restoring all of .result, .base.data
and .base.complete .

Also, remove the crypto_completion_t complete = ... line present in the
ahash_op_unaligned_done() function. This type actually declares a function
pointer, which is very confusing.

Finally, yet very important nonetheless, make sure the req->priv is free()'d
only after the original request is restored in ahash_op_unaligned_done().
The req->priv data must not be free()'d before that in ahash_op_unaligned_finish(),
since we would be accessing previously free()'d data in ahash_op_unaligned_done()
and cause corruption.

Signed-off-by: Marek Vasut 
Cc: David S. Miller 
Cc: Fabio Estevam 
Cc: Herbert Xu 
Cc: Shawn Guo 
Cc: Tom Lendacky 
Signed-off-by: Herbert Xu 
Signed-off-by: Ben Hutchings

crypto: ahash - Fully restore ahash request before completing

2017-06-05T20:13:55+00:00

commit 1d9a394b97b833d3ab37f49caf12d0be3c88050b upstream.

When finishing the ahash request, the ahash_op_unaligned_done() will
call complete() on the request. Yet, this will not call the correct
complete callback. The correct complete callback was previously stored
in the requests' private data, as seen in ahash_op_unaligned(). This
patch restores the correct complete callback and .data field of the
request before calling complete() on it.

Signed-off-by: Marek Vasut 
Cc: David S. Miller 
Cc: Fabio Estevam 
Cc: Shawn Guo 
Signed-off-by: Herbert Xu 
Signed-off-by: Ben Hutchings

crypto: hash - Fix page length clamping in hash walk

2016-06-15T20:28:14+00:00

commit 13f4bb78cf6a312bbdec367ba3da044b09bf0e29 upstream.

The crypto hash walk code is broken when supplied with an offset
greater than or equal to PAGE_SIZE.  This patch fixes it by adjusting
walk->pg and walk->offset when this happens.

Reported-by: Steffen Klassert 
Signed-off-by: Herbert Xu 
Signed-off-by: Ben Hutchings

crypto: hash - Add crypto_ahash_has_setkey

2016-02-13T10:34:12+00:00

commit a5596d6332787fd383b3b5427b41f94254430827 upstream.

This patch adds a way for ahash users to determine whether a key
is required by a crypto_ahash transform.

Signed-off-by: Herbert Xu 
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings

crypto: ahash - ensure statesize is non-zero

2015-11-17T15:54:43+00:00

commit 8996eafdcbad149ac0f772fb1649fbb75c482a6a upstream.

Unlike shash algorithms, ahash drivers must implement export
and import as their descriptors may contain hardware state and
cannot be exported as is.  Unfortunately some ahash drivers did
not provide them and end up causing crashes with algif_hash.

This patch adds a check to prevent these drivers from registering
ahash algorithms until they are fixed.

Signed-off-by: Russell King 
Signed-off-by: Herbert Xu 
Signed-off-by: Ben Hutchings