lkml.org 
[lkml]   [2019]   [Mar]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 5.0 041/238] crypto: hash - set CRYPTO_TFM_NEED_KEY if ->setkey() fails
Date
5.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Biggers <ebiggers@google.com>

commit ba7d7433a0e998c902132bd47330e355a1eaa894 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
crypto/ahash.c | 28 +++++++++++++++++++---------
crypto/shash.c | 18 +++++++++++++-----
2 files changed, 32 insertions(+), 14 deletions(-)

--- a/crypto/ahash.c
+++ b/crypto/ahash.c
@@ -190,6 +190,21 @@ static int ahash_setkey_unaligned(struct
return ret;
}

+static int ahash_nosetkey(struct crypto_ahash *tfm, const u8 *key,
+ unsigned int keylen)
+{
+ return -ENOSYS;
+}
+
+static void ahash_set_needkey(struct crypto_ahash *tfm)
+{
+ const struct hash_alg_common *alg = crypto_hash_alg_common(tfm);
+
+ if (tfm->setkey != ahash_nosetkey &&
+ !(alg->base.cra_flags & CRYPTO_ALG_OPTIONAL_KEY))
+ crypto_ahash_set_flags(tfm, CRYPTO_TFM_NEED_KEY);
+}
+
int crypto_ahash_setkey(struct crypto_ahash *tfm, const u8 *key,
unsigned int keylen)
{
@@ -201,20 +216,16 @@ int crypto_ahash_setkey(struct crypto_ah
else
err = tfm->setkey(tfm, key, keylen);

- if (err)
+ if (unlikely(err)) {
+ ahash_set_needkey(tfm);
return err;
+ }

crypto_ahash_clear_flags(tfm, CRYPTO_TFM_NEED_KEY);
return 0;
}
EXPORT_SYMBOL_GPL(crypto_ahash_setkey);

-static int ahash_nosetkey(struct crypto_ahash *tfm, const u8 *key,
- unsigned int keylen)
-{
- return -ENOSYS;
-}
-
static inline unsigned int ahash_align_buffer_size(unsigned len,
unsigned long mask)
{
@@ -489,8 +500,7 @@ static int crypto_ahash_init_tfm(struct

if (alg->setkey) {
hash->setkey = alg->setkey;
- if (!(alg->halg.base.cra_flags & CRYPTO_ALG_OPTIONAL_KEY))
- crypto_ahash_set_flags(hash, CRYPTO_TFM_NEED_KEY);
+ ahash_set_needkey(hash);
}

return 0;
--- a/crypto/shash.c
+++ b/crypto/shash.c
@@ -53,6 +53,13 @@ static int shash_setkey_unaligned(struct
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_sh
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 c
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

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;
}

\
 
 \ /
  Last update: 2019-03-22 13:36    [W:0.441 / U:11.276 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site