All of lore.kernel.org
 help / color / mirror / Atom feed
From: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
To: Eric Biggers <ebiggers@kernel.org>
Cc: Mimi Zohar <zohar@linux.ibm.com>,
	Vitaly Chikunov <vt@altlinux.org>,
	Stefan Berger <stefanb@linux.ibm.com>,
	Jarkko Sakkinen <jarkko@kernel.org>,
	Gilad Ben-Yossef <gilad@benyossef.com>,
	David Howells <dhowells@redhat.com>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	"David S. Miller" <davem@davemloft.net>,
	keyrings@vger.kernel.org, linux-crypto@vger.kernel.org,
	linux-integrity@vger.kernel.org
Subject: Re: [PATCH] KEYS: asymmetric: enforce SM2 signature use pkey algo
Date: Tue, 8 Feb 2022 17:45:40 +0800	[thread overview]
Message-ID: <8ca7c447-3fd6-612b-f903-3111eaddf6e6@linux.alibaba.com> (raw)
In-Reply-To: <YgIBKeFkiKtD1unK@sol.localdomain>

Hi Eric,

On 2/8/22 1:35 PM, Eric Biggers wrote:
> On Mon, Feb 07, 2022 at 07:43:27PM +0800, Tianjia Zhang wrote:
>> The signature verification of SM2 needs to add the Za value and
>> recalculate sig->digest, which requires the detection of the pkey_algo
>> in public_key_verify_signature(). As Eric Biggers said, the pkey_algo
>> field in sig is attacker-controlled and should be use pkey->pkey_algo
>> instead of sig->pkey_algo, and secondly, if sig->pkey_algo is NULL, it
>> will also cause signature verification failure.
>>
>> The software_key_determine_akcipher() already forces the algorithms
>> are matched, so the SM3 algorithm is enforced in the SM2 signature,
>> although this has been checked, we still avoid using any algorithm
>> information in the signature as input.
>>
>> Reported-by: Eric Biggers <ebiggers@google.com>
>> Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
> 
> Can you add a Fixes tag?
> 

Thanks, the v2 patch with Fixes tag added has been appended to your
v2 series.

>> ---
>>   crypto/asymmetric_keys/public_key.c | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
>> index a603ee8afdb8..ea9a5501f87e 100644
>> --- a/crypto/asymmetric_keys/public_key.c
>> +++ b/crypto/asymmetric_keys/public_key.c
>> @@ -309,7 +309,8 @@ static int cert_sig_digest_update(const struct public_key_signature *sig,
>>   	if (ret)
>>   		return ret;
>>   
>> -	tfm = crypto_alloc_shash(sig->hash_algo, 0, 0);
>> +	/* SM2 signatures always use the SM3 hash algorithm */
>> +	tfm = crypto_alloc_shash("sm3", 0, 0);
>>   	if (IS_ERR(tfm))
>>   		return PTR_ERR(tfm);
>>   
>> @@ -414,8 +415,7 @@ int public_key_verify_signature(const struct public_key *pkey,
>>   	if (ret)
>>   		goto error_free_key;
>>   
>> -	if (sig->pkey_algo && strcmp(sig->pkey_algo, "sm2") == 0 &&
>> -	    sig->data_size) {
>> +	if (strcmp(pkey->pkey_algo, "sm2") == 0 && sig->data_size) {
>>   		ret = cert_sig_digest_update(sig, tfm);
>>   		if (ret)
>>   			goto error_free_key;
>> -- 
> 
> This is an improvement, but do you also have a plan to address the problem where
> the code allows the "Za" hash step to be skipped?  The definitions of SM2 that I
> could find require that step.  So, it is unclear that the algorithm with that
> step skipped is still SM2, and how its security relates to that of the SM2
> algorithm as actually defined.
> 
> - Eric
The design of this Za has indeed brought us a lot of trouble, which
makes the two separate steps of calculating the hash and signature
forced to be coupled together. At present, it is a better way to design
skipping Za as an option. I will try to do this, which of course also
includes application layer libraries, like openssl.

Best regards,
Tianjia

  reply	other threads:[~2022-02-08 11:30 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-01  0:34 [PATCH 0/2] Fix bugs in public_key_verify_signature() Eric Biggers
2022-02-01  0:34 ` [PATCH 1/2] KEYS: asymmetric: enforce that sig algo matches key algo Eric Biggers
2022-02-02  2:52   ` Vitaly Chikunov
2022-02-02  3:10     ` Eric Biggers
2022-02-02  3:22       ` Eric Biggers
2022-02-02  5:20       ` Vitaly Chikunov
2022-02-21  1:43   ` Jarkko Sakkinen
2022-03-04 19:26     ` Eric Biggers
2022-03-05  5:51       ` Jarkko Sakkinen
2022-02-01  0:34 ` [PATCH 2/2] KEYS: asymmetric: properly validate hash_algo and encoding Eric Biggers
2022-02-21  1:46   ` Jarkko Sakkinen
2022-02-21  2:21     ` Eric Biggers
2022-02-21 20:16       ` Jarkko Sakkinen
2022-02-01  2:38 ` [PATCH 0/2] Fix bugs in public_key_verify_signature() Stefan Berger
2022-02-07  7:45 ` Tianjia Zhang
2022-02-07 11:43 ` [PATCH] KEYS: asymmetric: enforce SM2 signature use pkey algo Tianjia Zhang
2022-02-08  5:35   ` Eric Biggers
2022-02-08  9:45     ` Tianjia Zhang [this message]
2022-02-21  1:49   ` Jarkko Sakkinen
2022-02-21  2:43     ` Tianjia Zhang
2022-02-21 20:17       ` Jarkko Sakkinen

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=8ca7c447-3fd6-612b-f903-3111eaddf6e6@linux.alibaba.com \
    --to=tianjia.zhang@linux.alibaba.com \
    --cc=davem@davemloft.net \
    --cc=dhowells@redhat.com \
    --cc=ebiggers@kernel.org \
    --cc=gilad@benyossef.com \
    --cc=herbert@gondor.apana.org.au \
    --cc=jarkko@kernel.org \
    --cc=keyrings@vger.kernel.org \
    --cc=linux-crypto@vger.kernel.org \
    --cc=linux-integrity@vger.kernel.org \
    --cc=stefanb@linux.ibm.com \
    --cc=vt@altlinux.org \
    --cc=zohar@linux.ibm.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.