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fscrypt: verify that the crypto_skcipher has the correct ivsize

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As a sanity check, verify that the allocated crypto_skcipher actually
has the ivsize that fscrypt is assuming it has.  This will always be the
case unless there's a bug.  But if there ever is such a bug (e.g. like
there was in earlier versions of the ESSIV conversion patch [1]) it's
preferable for it to be immediately obvious, and not rely on the
ciphertext verification tests failing due to uninitialized IV bytes.

[1] https://lkml.kernel.org/linux-crypto/20190702215517.GA69157@gmail.com/

Link: https://lore.kernel.org/r/20191209203918.225691-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
This commit is contained in:
Eric Biggers 2019-12-09 12:39:18 -08:00
parent 6e1adb88d2
commit c64cfb989f
1 changed files with 4 additions and 0 deletions
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4
fs/crypto/keysetup.c
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@ -91,6 +91,10 @@ struct crypto_skcipher *fscrypt_allocate_skcipher(struct fscrypt_mode *mode,
pr_info("fscrypt: %s using implementation \"%s\"\n", pr_info("fscrypt: %s using implementation \"%s\"\n",
mode->friendly_name, crypto_skcipher_driver_name(tfm)); mode->friendly_name, crypto_skcipher_driver_name(tfm));
} }
if (WARN_ON(crypto_skcipher_ivsize(tfm) != mode->ivsize)) {
err = -EINVAL;
goto err_free_tfm;
}
crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS); crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
err = crypto_skcipher_setkey(tfm, raw_key, mode->keysize); err = crypto_skcipher_setkey(tfm, raw_key, mode->keysize);
if (err) if (err)