[PATCH v3] crypto: gcm - restrict assoclen for rfc4543

[PATCH v3] crypto: gcm - restrict assoclen for rfc4543

[Iuliana Prodan]

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 <iuliana.prodan@nxp.com>
---
Changes since v2:
- use, newly renamed, helper functions added in crypto API, in series:
https://patchwork.kernel.org/project/linux-crypto/list/?series=152649

 crypto/gcm.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/crypto/gcm.c b/crypto/gcm.c
index 2f3b50f..7eb5ced 100644
--- a/crypto/gcm.c
+++ b/crypto/gcm.c
@@ -1034,11 +1034,23 @@ static int crypto_rfc4543_copy_src_to_dst(struct aead_request *req, bool enc)
 
 static int crypto_rfc4543_encrypt(struct aead_request *req)
 {
+	int err;
+
+	err = crypto_ipsec_check_assoclen(req->assoclen);
+	if (err)
+		return err;
+
 	return crypto_rfc4543_crypt(req, true);
 }
 
 static int crypto_rfc4543_decrypt(struct aead_request *req)
 {
+	int err;
+
+	err = crypto_ipsec_check_assoclen(req->assoclen);
+	if (err)
+		return err;
+
 	return crypto_rfc4543_crypt(req, false);
 }
 
-- 
2.1.0

Re: [PATCH v3] crypto: gcm - restrict assoclen for rfc4543

[Horia Geanta]

On 7/30/2019 2:03 PM, Iuliana Prodan wrote:
> 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 <iuliana.prodan@nxp.com>
Reviewed-by: Horia Geantă <horia.geanta@nxp.com>

[...]
> diff --git a/crypto/gcm.c b/crypto/gcm.c
> index 2f3b50f..7eb5ced 100644
> --- a/crypto/gcm.c
> +++ b/crypto/gcm.c
> @@ -1034,11 +1034,23 @@ static int crypto_rfc4543_copy_src_to_dst(struct aead_request *req, bool enc)
>  
>  static int crypto_rfc4543_encrypt(struct aead_request *req)
>  {
> +	int err;
> +
> +	err = crypto_ipsec_check_assoclen(req->assoclen);
> +	if (err)
> +		return err;
> +
>  	return crypto_rfc4543_crypt(req, true);
>  }
Could as well be:
	return crypto_ipsec_check_assoclen(req->assoclen) ?:
	       crypto_rfc4543_crypt(req, true);

The same for decryption.

Horia