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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 <syzkaller@googlegroups.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
[bwh: Backported to 3.16:
- In hash_accept_parent_nokey(), update initialisation of ds to use tfm
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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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 <herbert@gondor.apana.org.au>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
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When an shash algorithm is exported as ahash, ahash will access
its digest size through hash_alg_common. That's why the shash
layout needs to match hash_alg_common. This wasn't the case
because the alignment weren't identical.
This patch fixes the problem.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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This patch exports the finup operation where available and adds
a default finup operation for ahash. The operations final, finup
and digest also will now deal with unaligned result pointers by
copying it. Finally export/import operations are will now be
exported too.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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Now that all ahash implementations have been converted to the new
ahash type, we can remove old_ahash_alg and its associated support.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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This patch converts crypto_ahash to the new style. The old ahash
algorithm type is retained until the existing ahash implementations
are also converted. All ahash users will automatically get the
new crypto_ahash type.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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This patch changes descsize to a run-time attribute so that
implementations can change it in their init functions.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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This patch changes the kfree call to kzfree for async requests.
As the request may contain sensitive data it needs to be zeroed
before it can be reallocated by others.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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This patch replaces the full descriptor export with an export of
the partial hash state. This allows the use of a consistent export
format across all implementations of a given algorithm.
This is useful because a number of cases require the use of the
partial hash state, e.g., PadLock can use the SHA1 hash state
to get around the fact that it can only hash contiguous data
chunks.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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This function is needed by algorithms that don't know their own
block size, e.g., in s390 where the code is common between multiple
versions of SHA.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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We were freeing an offset into the slab object instead of the
start. This patch fixes it by calling crypto_destroy_tfm which
allows the correct address to be given.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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It is often useful to save the partial state of a hash function
so that it can be used as a base for two or more computations.
The most prominent example is HMAC where all hashes start from
a base determined by the key. Having an import/export interface
means that we only have to compute that base once rather than
for each message.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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The shash interface replaces the current synchronous hash interface.
It improves over hash in two ways. Firstly shash is reentrant,
meaning that the same tfm may be used by two threads simultaneously
as all hashing state is stored in a local descriptor.
The other enhancement is that shash no longer takes scatter list
entries. This is because shash is specifically designed for
synchronous algorithms and as such scatter lists are unnecessary.
All existing hash users will be converted to shash once the
algorithms have been completely converted.
There is also a new finup function that combines update with final.
This will be extended to ahash once the algorithm conversion is
done.
This is also the first time that an algorithm type has their own
registration function. Existing algorithm types will be converted
to this way in due course.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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The top-level functions init/update/final were missing for ahash.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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All new crypto interfaces should go into individual files as much
as possible in order to ensure that crypto.h does not collapse under
its own weight.
This patch moves the ahash code into crypto/hash.h and crypto/internal/hash.h
respectively.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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