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From: Jessica Yu <>
To: Stefan Berger <>
Subject: Re: [PATCH v2 2/2] certs: Add support for using elliptic curve keys for signing modules
Date: Wed, 21 Apr 2021 14:52:06 +0200
Message-ID: <YIAf9jYGu03lrJLn@gunter> (raw)
In-Reply-To: <>

+++ Stefan Berger [20/04/21 17:02 -0400]:
>On 4/20/21 10:03 AM, Jessica Yu wrote:
>>+++ Stefan Berger [08/04/21 11:24 -0400]:
>>>diff --git a/crypto/asymmetric_keys/pkcs7_parser.c 
>>>index 967329e0a07b..2546ec6a0505 100644
>>>--- a/crypto/asymmetric_keys/pkcs7_parser.c
>>>+++ b/crypto/asymmetric_keys/pkcs7_parser.c
>>>@@ -269,6 +269,10 @@ int pkcs7_sig_note_pkey_algo(void *context, 
>>>size_t hdrlen,
>>>        ctx->sinfo->sig->pkey_algo = "rsa";
>>>        ctx->sinfo->sig->encoding = "pkcs1";
>>>        break;
>>>+    case OID_id_ecdsa_with_sha256:
>>>+        ctx->sinfo->sig->pkey_algo = "ecdsa";
>>>+        ctx->sinfo->sig->encoding = "x962";
>>>+        break;
>>Hi Stefan,
>>Does CONFIG_MODULE_SIG_KEY_TYPE_ECDSA have a dependency on 
>You are right, per the code above it does have a dependency on SHA256. 
>ECDSA is using NIST p384 (secp384r1) for signing and per my tests it 
>can be paired with all the sha hashes once the code above is extended. 
>Now when it comes to module signing, should we pair it with a 
>particular hash? I am not currently aware of a guidance document on 
>this but sha256 and sha384 seem to be good choices these days, so 
>maybe selecting ECDSA module signing should have a 'depends on' on 

Yeah, I would tack on the 'depends on' until the code above has been
extended to cover more sha hashes - because currently if someone
builds and signs a bunch of modules with an ECDSA key, they will fail
to load if they picked something other than sha256. I am unfortunately
not knowledgeable enough to suggest an official guideline on choice of
hash, but for now it is reasonable to have a 'depends on' for which
hashes the code currently supports, so that users don't run into
module loading rejection issues.



  reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-08 15:24 [PATCH v2 0/2] Add support for ECDSA-signed kernel modules Stefan Berger
2021-04-08 15:24 ` [PATCH v2 1/2] certs: Trigger creation of RSA module signing key if it's not an RSA key Stefan Berger
2021-04-08 17:15   ` Mimi Zohar
2021-04-08 19:19     ` Stefan Berger
2021-04-08 21:34       ` Mimi Zohar
2021-04-08 15:24 ` [PATCH v2 2/2] certs: Add support for using elliptic curve keys for signing modules Stefan Berger
2021-04-08 17:15   ` Mimi Zohar
2021-04-20 14:03   ` Jessica Yu
2021-04-20 21:02     ` Stefan Berger
2021-04-21 12:52       ` Jessica Yu [this message]
2021-04-21 12:54         ` Stefan Berger
2021-04-21 12:58           ` Jessica Yu

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