crypto: gcm - restrict assoclen for rfc4543

Based on seqiv, IPsec ESP and rfc4543/rfc4106 the assoclen can be 16 or
20 bytes.

From esp4/esp6, assoclen is sizeof IP Header. This includes spi, seq_no
and extended seq_no, that is 8 or 12 bytes.
In seqiv, to asscolen is added the IV size (8 bytes).
Therefore, the assoclen, for rfc4543, should be restricted to 16 or 20
bytes, as for rfc4106.

Signed-off-by: Iuliana Prodan <[e-mail]>
Reviewed-by: Horia Geanta <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

crypto/gcm.c

···
 
 static int crypto_rfc4543_encrypt(struct aead_request *req)
 {
-	return crypto_rfc4543_crypt(req, true);
+	return crypto_ipsec_check_assoclen(req->assoclen) ?:
+	       crypto_rfc4543_crypt(req, true);
 }
 
 static int crypto_rfc4543_decrypt(struct aead_request *req)
 {
-	return crypto_rfc4543_crypt(req, false);
+	return crypto_ipsec_check_assoclen(req->assoclen) ?:
+	       crypto_rfc4543_crypt(req, false);
 }
 
 static int crypto_rfc4543_init_tfm(struct crypto_aead *tfm)