4.19-stable review patch. If anyone has any objections, please let me know.
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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 @@ -584,6 +584,12 @@ 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) { @@ -597,8 +603,10 @@ 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; @@ -676,8 +684,7 @@ 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; } @@ -697,8 +704,10 @@ 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; @@ -775,8 +784,7 @@ 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; } @@ -819,8 +827,10 @@ 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;