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 5.0 044/238] crypto: skcipher - 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 b1f6b4bf416b49f00f3abc49c639371cdecaaad1 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.

For example, in lrw.c, if gf128mul_init_64k_bbe() fails due to lack of
memory, then priv::table will be left NULL. After that, encryption with
that tfm will cause a NULL pointer dereference.

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.

[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: f8d33fac8480 ("crypto: skcipher - prevent using skciphers without setting key")
Cc: <stable@vger.kernel.org> # v4.16+
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/skcipher.c | 27 ++++++++++++++++++---------
1 file changed, 18 insertions(+), 9 deletions(-)

--- a/crypto/skcipher.c
+++ b/crypto/skcipher.c
@@ -585,6 +585,12 @@ static unsigned int crypto_skcipher_exts
return crypto_alg_extsize(alg);
}

+static void skcipher_set_needkey(struct crypto_skcipher *tfm)
+{
+ if (tfm->keysize)
+ crypto_skcipher_set_flags(tfm, CRYPTO_TFM_NEED_KEY);
+}
+
static int skcipher_setkey_blkcipher(struct crypto_skcipher *tfm,
const u8 *key, unsigned int keylen)
{
@@ -598,8 +604,10 @@ static int skcipher_setkey_blkcipher(str
err = crypto_blkcipher_setkey(blkcipher, key, keylen);
crypto_skcipher_set_flags(tfm, crypto_blkcipher_get_flags(blkcipher) &
CRYPTO_TFM_RES_MASK);
- if (err)
+ if (unlikely(err)) {
+ skcipher_set_needkey(tfm);
return err;
+ }

crypto_skcipher_clear_flags(tfm, CRYPTO_TFM_NEED_KEY);
return 0;
@@ -677,8 +685,7 @@ static int crypto_init_skcipher_ops_blkc
skcipher->ivsize = crypto_blkcipher_ivsize(blkcipher);
skcipher->keysize = calg->cra_blkcipher.max_keysize;

- if (skcipher->keysize)
- crypto_skcipher_set_flags(skcipher, CRYPTO_TFM_NEED_KEY);
+ skcipher_set_needkey(skcipher);

return 0;
}
@@ -698,8 +705,10 @@ static int skcipher_setkey_ablkcipher(st
crypto_skcipher_set_flags(tfm,
crypto_ablkcipher_get_flags(ablkcipher) &
CRYPTO_TFM_RES_MASK);
- if (err)
+ if (unlikely(err)) {
+ skcipher_set_needkey(tfm);
return err;
+ }

crypto_skcipher_clear_flags(tfm, CRYPTO_TFM_NEED_KEY);
return 0;
@@ -776,8 +785,7 @@ static int crypto_init_skcipher_ops_ablk
sizeof(struct ablkcipher_request);
skcipher->keysize = calg->cra_ablkcipher.max_keysize;

- if (skcipher->keysize)
- crypto_skcipher_set_flags(skcipher, CRYPTO_TFM_NEED_KEY);
+ skcipher_set_needkey(skcipher);

return 0;
}
@@ -820,8 +828,10 @@ static int skcipher_setkey(struct crypto
else
err = cipher->setkey(tfm, key, keylen);

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

crypto_skcipher_clear_flags(tfm, CRYPTO_TFM_NEED_KEY);
return 0;
@@ -852,8 +862,7 @@ static int crypto_skcipher_init_tfm(stru
skcipher->ivsize = alg->ivsize;
skcipher->keysize = alg->max_keysize;

- if (skcipher->keysize)
- crypto_skcipher_set_flags(skcipher, CRYPTO_TFM_NEED_KEY);
+ skcipher_set_needkey(skcipher);

if (alg->exit)
skcipher->base.exit = crypto_skcipher_exit_tfm;

\
 
 \ /
  Last update: 2019-03-22 13:39    [W:0.514 / U:22.832 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site