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authorEric Biggers <ebiggers@google.com>2019-01-06 18:47:42 -0800
committerHerbert Xu <herbert@gondor.apana.org.au>2019-01-18 18:40:24 +0800
commitba7d7433a0e998c902132bd47330e355a1eaa894 (patch)
tree173b444702f5d2114d687711b3376477dbbde26b /crypto/shash.c
parent6b476662b09c393936e0f62c97ad9988d410fd36 (diff)
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crypto: hash - set CRYPTO_TFM_NEED_KEY if ->setkey() fails
Some algorithms have a ->setkey() method that is not atomic, in the sense that setting a key can fail after changes were already made to the tfm context. In this case, if a key was already set the tfm can end up in a state that corresponds to neither the old key nor the new key. It's not feasible to make all ->setkey() methods atomic, especially ones that have to key multiple sub-tfms. Therefore, make the crypto API set CRYPTO_TFM_NEED_KEY if ->setkey() fails and the algorithm requires a key, to prevent the tfm from being used until a new key is set. Note: we can't set CRYPTO_TFM_NEED_KEY for OPTIONAL_KEY algorithms, so ->setkey() for those must nevertheless be atomic. That's fine for now since only the crc32 and crc32c algorithms set OPTIONAL_KEY, and it's not intended that OPTIONAL_KEY be used much. [Cc stable mainly because when introducing the NEED_KEY flag I changed AF_ALG to rely on it; and unlike in-kernel crypto API users, AF_ALG previously didn't have this problem. So these "incompletely keyed" states became theoretically accessible via AF_ALG -- though, the opportunities for causing real mischief seem pretty limited.] Fixes: 9fa68f620041 ("crypto: hash - prevent using keyed hashes without setting key") Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto/shash.c')
-rw-r--r--crypto/shash.c18
1 files changed, 13 insertions, 5 deletions
diff --git a/crypto/shash.c b/crypto/shash.c
index 44d297b82a8f..40311ccad3fa 100644
--- a/crypto/shash.c
+++ b/crypto/shash.c
@@ -53,6 +53,13 @@ static int shash_setkey_unaligned(struct crypto_shash *tfm, const u8 *key,
return err;
}
+static void shash_set_needkey(struct crypto_shash *tfm, struct shash_alg *alg)
+{
+ if (crypto_shash_alg_has_setkey(alg) &&
+ !(alg->base.cra_flags & CRYPTO_ALG_OPTIONAL_KEY))
+ crypto_shash_set_flags(tfm, CRYPTO_TFM_NEED_KEY);
+}
+
int crypto_shash_setkey(struct crypto_shash *tfm, const u8 *key,
unsigned int keylen)
{
@@ -65,8 +72,10 @@ int crypto_shash_setkey(struct crypto_shash *tfm, const u8 *key,
else
err = shash->setkey(tfm, key, keylen);
- if (err)
+ if (unlikely(err)) {
+ shash_set_needkey(tfm, shash);
return err;
+ }
crypto_shash_clear_flags(tfm, CRYPTO_TFM_NEED_KEY);
return 0;
@@ -373,7 +382,8 @@ int crypto_init_shash_ops_async(struct crypto_tfm *tfm)
crt->final = shash_async_final;
crt->finup = shash_async_finup;
crt->digest = shash_async_digest;
- crt->setkey = shash_async_setkey;
+ if (crypto_shash_alg_has_setkey(alg))
+ crt->setkey = shash_async_setkey;
crypto_ahash_set_flags(crt, crypto_shash_get_flags(shash) &
CRYPTO_TFM_NEED_KEY);
@@ -395,9 +405,7 @@ static int crypto_shash_init_tfm(struct crypto_tfm *tfm)
hash->descsize = alg->descsize;
- if (crypto_shash_alg_has_setkey(alg) &&
- !(alg->base.cra_flags & CRYPTO_ALG_OPTIONAL_KEY))
- crypto_shash_set_flags(hash, CRYPTO_TFM_NEED_KEY);
+ shash_set_needkey(hash, alg);
return 0;
}