[PATCH v2 18/18] keyctl_pkey: Add pkey parameters slen and mgfhash for PSS

[PATCH v2 18/18] keyctl_pkey: Add pkey parameters slen and mgfhash for PSS

[Varad Gautam]

keyctl pkey_* operations accept enc and hash parameters at present.
RSASSA-PSS signatures also require passing in the signature salt
length and the mgf hash function.

Add parameters:
- 'slen' to feed in salt length of a PSS signature.
- 'mgfhash' to feed in the hash function used for MGF.

Signed-off-by: Varad Gautam <varad.gautam@suse.com>
CC: Jarkko Sakkinen <jarkko@kernel.org>
---
v2: Accept 'mgfhash' as a parameter. v1 assumed this to be the same
  as the digest hash.

 crypto/asymmetric_keys/asymmetric_type.c |  2 ++
 include/linux/keyctl.h                   |  2 ++
 security/keys/keyctl_pkey.c              | 13 +++++++++++++
 3 files changed, 17 insertions(+)

diff --git a/crypto/asymmetric_keys/asymmetric_type.c b/crypto/asymmetric_keys/asymmetric_type.c
index ad8af3d70ac04..72c1bf964826f 100644
--- a/crypto/asymmetric_keys/asymmetric_type.c
+++ b/crypto/asymmetric_keys/asymmetric_type.c
@@ -571,6 +571,8 @@ static int asymmetric_key_verify_signature(struct kernel_pkey_params *params,
 		.hash_algo	= params->hash_algo,
 		.digest		= (void *)in,
 		.s		= (void *)in2,
+		.salt_length	= params->slen,
+		.mgf_hash_algo	= params->mgf_hash_algo,
 	};
 
 	return verify_signature(params->key, &sig);
diff --git a/include/linux/keyctl.h b/include/linux/keyctl.h
index 5b79847207ef2..753d004d76ece 100644
--- a/include/linux/keyctl.h
+++ b/include/linux/keyctl.h
@@ -37,6 +37,8 @@ struct kernel_pkey_params {
 		__u32	in2_len;	/* 2nd input data size (verify) */
 	};
 	enum kernel_pkey_operation op : 8;
+	__u32		slen;
+	const char	*mgf_hash_algo;
 };
 
 #endif /* __LINUX_KEYCTL_H */
diff --git a/security/keys/keyctl_pkey.c b/security/keys/keyctl_pkey.c
index 5de0d599a2748..ae3a81c726322 100644
--- a/security/keys/keyctl_pkey.c
+++ b/security/keys/keyctl_pkey.c
@@ -24,11 +24,15 @@ enum {
 	Opt_err,
 	Opt_enc,		/* "enc=<encoding>" eg. "enc=oaep" */
 	Opt_hash,		/* "hash=<digest-name>" eg. "hash=sha1" */
+	Opt_slen,		/* "slen=<salt-length>" eg. "slen=32" */
+	Opt_mgfhash,		/* "mgfhash=<digest-name>" eg. "mgfhash=sha1" */
 };
 
 static const match_table_t param_keys = {
 	{ Opt_enc,	"enc=%s" },
 	{ Opt_hash,	"hash=%s" },
+	{ Opt_slen,	"slen=%u" },
+	{ Opt_mgfhash,	"mgfhash=%s" },
 	{ Opt_err,	NULL }
 };
 
@@ -63,6 +67,15 @@ static int keyctl_pkey_params_parse(struct kernel_pkey_params *params)
 			params->hash_algo = q;
 			break;
 
+		case Opt_slen:
+			if (kstrtouint(q, 0, &params->slen))
+				return -EINVAL;
+			break;
+
+		case Opt_mgfhash:
+			params->mgf_hash_algo = q;
+			break;
+
 		default:
 			return -EINVAL;
 		}
-- 
2.30.2

Re: [PATCH v2 18/18] keyctl_pkey: Add pkey parameters slen and mgfhash for PSS

[Ben Boeckel]

On Thu, Apr 08, 2021 at 16:15:16 +0200, Varad Gautam wrote:
> keyctl pkey_* operations accept enc and hash parameters at present.
> RSASSA-PSS signatures also require passing in the signature salt
> length and the mgf hash function.
> 
> Add parameters:
> - 'slen' to feed in salt length of a PSS signature.
> - 'mgfhash' to feed in the hash function used for MGF.

Could `Documentation/security/keys/core.rst` be updated to mention these
new parameters? Statements on what values are allowed would be
appreciated as well (e.g., that `saltlen` (a far better name IMO) is
unsigned 32-bits and where valid algorithm names could be found as
well).

Thanks,

--Ben

Re: [PATCH v2 18/18] keyctl_pkey: Add pkey parameters slen and mgfhash for PSS

[Varad Gautam]

On 4/9/21 4:15 PM, Ben Boeckel wrote:
> On Thu, Apr 08, 2021 at 16:15:16 +0200, Varad Gautam wrote:
>> keyctl pkey_* operations accept enc and hash parameters at present.
>> RSASSA-PSS signatures also require passing in the signature salt
>> length and the mgf hash function.
>>
>> Add parameters:
>> - 'slen' to feed in salt length of a PSS signature.
>> - 'mgfhash' to feed in the hash function used for MGF.
> 
> Could `Documentation/security/keys/core.rst` be updated to mention these
> new parameters? Statements on what values are allowed would be
> appreciated as well (e.g., that `saltlen` (a far better name IMO) is
> unsigned 32-bits and where valid algorithm names could be found as
> well).
> 

Thanks, I've added these to v3.

> Thanks,
> 
> --Ben
> 

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Re: [PATCH v2 18/18] keyctl_pkey: Add pkey parameters slen and mgfhash for PSS

[David Howells]

Varad Gautam <varad.gautam@suse.com> wrote:

> +	Opt_slen,		/* "slen=<salt-length>" eg. "slen=32" */

"slen" seems a bit unobvious.  Maybe "saltlen=..."?

David