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| author | Ard Biesheuvel <ardb@kernel.org> | 2020-11-17 14:32:11 +0100 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2020-11-27 17:13:39 +1100 |
| commit | 02685906d3afa4f7c72d86cf99242e3b08078865 (patch) | |
| tree | b7f7dc34b6fb06cd27e8e42f43d809065c7f163c /crypto | |
| parent | 732b764099f651a088fd931d7b8121b6aa84e62e (diff) | |
| download | linux-02685906d3afa4f7c72d86cf99242e3b08078865.tar.bz2 | |
crypto: aegis128 - wipe plaintext and tag if decryption fails
The AEGIS spec mentions explicitly that the security guarantees hold
only if the resulting plaintext and tag of a failed decryption are
withheld. So ensure that we abide by this.
While at it, drop the unused struct aead_request *req parameter from
crypto_aegis128_process_crypt().
Reviewed-by: Ondrej Mosnacek <omosnacek@gmail.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto')
| -rw-r--r-- | crypto/aegis128-core.c | 32 |
1 files changed, 26 insertions, 6 deletions
diff --git a/crypto/aegis128-core.c b/crypto/aegis128-core.c index 44fb4956f0dd..3a71235892f5 100644 --- a/crypto/aegis128-core.c +++ b/crypto/aegis128-core.c @@ -154,6 +154,12 @@ static void crypto_aegis128_ad(struct aegis_state *state, } } +static void crypto_aegis128_wipe_chunk(struct aegis_state *state, u8 *dst, + const u8 *src, unsigned int size) +{ + memzero_explicit(dst, size); +} + static void crypto_aegis128_encrypt_chunk(struct aegis_state *state, u8 *dst, const u8 *src, unsigned int size) { @@ -324,7 +330,6 @@ static void crypto_aegis128_process_ad(struct aegis_state *state, static __always_inline int crypto_aegis128_process_crypt(struct aegis_state *state, - struct aead_request *req, struct skcipher_walk *walk, void (*crypt)(struct aegis_state *state, u8 *dst, const u8 *src, @@ -403,14 +408,14 @@ static int crypto_aegis128_encrypt(struct aead_request *req) if (aegis128_do_simd()) { crypto_aegis128_init_simd(&state, &ctx->key, req->iv); crypto_aegis128_process_ad(&state, req->src, req->assoclen); - crypto_aegis128_process_crypt(&state, req, &walk, + crypto_aegis128_process_crypt(&state, &walk, crypto_aegis128_encrypt_chunk_simd); crypto_aegis128_final_simd(&state, &tag, req->assoclen, cryptlen); } else { crypto_aegis128_init(&state, &ctx->key, req->iv); crypto_aegis128_process_ad(&state, req->src, req->assoclen); - crypto_aegis128_process_crypt(&state, req, &walk, + crypto_aegis128_process_crypt(&state, &walk, crypto_aegis128_encrypt_chunk); crypto_aegis128_final(&state, &tag, req->assoclen, cryptlen); } @@ -438,19 +443,34 @@ static int crypto_aegis128_decrypt(struct aead_request *req) if (aegis128_do_simd()) { crypto_aegis128_init_simd(&state, &ctx->key, req->iv); crypto_aegis128_process_ad(&state, req->src, req->assoclen); - crypto_aegis128_process_crypt(&state, req, &walk, + crypto_aegis128_process_crypt(&state, &walk, crypto_aegis128_decrypt_chunk_simd); crypto_aegis128_final_simd(&state, &tag, req->assoclen, cryptlen); } else { crypto_aegis128_init(&state, &ctx->key, req->iv); crypto_aegis128_process_ad(&state, req->src, req->assoclen); - crypto_aegis128_process_crypt(&state, req, &walk, + crypto_aegis128_process_crypt(&state, &walk, crypto_aegis128_decrypt_chunk); crypto_aegis128_final(&state, &tag, req->assoclen, cryptlen); } - return crypto_memneq(tag.bytes, zeros, authsize) ? -EBADMSG : 0; + if (unlikely(crypto_memneq(tag.bytes, zeros, authsize))) { + /* + * From Chapter 4. 'Security Analysis' of the AEGIS spec [0] + * + * "3. If verification fails, the decrypted plaintext and the + * wrong authentication tag should not be given as output." + * + * [0] https://competitions.cr.yp.to/round3/aegisv11.pdf + */ + skcipher_walk_aead_decrypt(&walk, req, false); + crypto_aegis128_process_crypt(NULL, &walk, + crypto_aegis128_wipe_chunk); + memzero_explicit(&tag, sizeof(tag)); + return -EBADMSG; + } + return 0; } static struct aead_alg crypto_aegis128_alg = { |