2019-07-30 12:08:23

by Iuliana Prodan

Subject: [PATCH v3] 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 <[email protected]>
---
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

2019-07-30 12:17:26

by Horia Geanta

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

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 <[email protected]>
Reviewed-by: Horia Geant? <[email protected]>

[...]
> 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