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SubjectRe: [PATCH v10 5/9] x509: Detect sm2 keys by their parameters OID
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On 3/5/21 12:16 PM, Jarkko Sakkinen wrote:
> On Thu, Mar 04, 2021 at 07:51:59PM -0500, Stefan Berger wrote:
>> From: Stefan Berger <stefanb@linux.ibm.com>
>>
>> Detect whether a key is an sm2 type of key by its OID in the parameters
>> array rather than assuming that everything under OID_id_ecPublicKey
>> is sm2, which is not the case.
>>
>> Cc: David Howells <dhowells@redhat.com>
>> Cc: keyrings@vger.kernel.org
>> Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
>> Reviewed-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
>> ---
>> crypto/asymmetric_keys/x509_cert_parser.c | 12 +++++++++++-
>> include/linux/oid_registry.h | 1 +
>> lib/oid_registry.c | 13 +++++++++++++
>> 3 files changed, 25 insertions(+), 1 deletion(-)
>>
>> diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
>> index 52c9b455fc7d..1621ceaf5c95 100644
>> --- a/crypto/asymmetric_keys/x509_cert_parser.c
>> +++ b/crypto/asymmetric_keys/x509_cert_parser.c
>> @@ -459,6 +459,7 @@ int x509_extract_key_data(void *context, size_t hdrlen,
>> const void *value, size_t vlen)
>> {
>> struct x509_parse_context *ctx = context;
>> + enum OID oid;
> enum is not a real type, and it is hard to recall how much it allocates
> from stack. I would replace this with plain int.


That would be worse considering existing code:
https://elixir.bootlin.com/linux/latest/source/lib/oid_registry.c#L25


>
>>
>> ctx->key_algo = ctx->last_oid;
>> switch (ctx->last_oid) {
>> @@ -470,7 +471,16 @@ int x509_extract_key_data(void *context, size_t hdrlen,
>> ctx->cert->pub->pkey_algo = "ecrdsa";
>> break;
>> case OID_id_ecPublicKey:
>> - ctx->cert->pub->pkey_algo = "sm2";
>> + if (parse_OID(ctx->params, ctx->params_size, &oid) != 0)
>> + return -EBADMSG;
>> +
>> + switch (oid) {
>> + case OID_sm2:
>> + ctx->cert->pub->pkey_algo = "sm2";
>> + break;
>> + default:
>> + return -ENOPKG;
>> + }
>> break;
>> default:
>> return -ENOPKG;
>> diff --git a/include/linux/oid_registry.h b/include/linux/oid_registry.h
>> index b504e2f36b25..f32d91895e4d 100644
>> --- a/include/linux/oid_registry.h
>> +++ b/include/linux/oid_registry.h
>> @@ -121,6 +121,7 @@ enum OID {
>> };
>>
>> extern enum OID look_up_OID(const void *data, size_t datasize);
>> +extern int parse_OID(const void *data, size_t datasize, enum OID *oid);
>> extern int sprint_oid(const void *, size_t, char *, size_t);
>> extern int sprint_OID(enum OID, char *, size_t);
>>
>> diff --git a/lib/oid_registry.c b/lib/oid_registry.c
>> index f7ad43f28579..508e0b34b5f0 100644
>> --- a/lib/oid_registry.c
>> +++ b/lib/oid_registry.c
>> @@ -11,6 +11,7 @@
>> #include <linux/kernel.h>
>> #include <linux/errno.h>
>> #include <linux/bug.h>
>> +#include <linux/asn1.h>
>> #include "oid_registry_data.c"
>>
>> MODULE_DESCRIPTION("OID Registry");
>> @@ -92,6 +93,18 @@ enum OID look_up_OID(const void *data, size_t datasize)
>> }
>> EXPORT_SYMBOL_GPL(look_up_OID);
>>
>> +int parse_OID(const void *data, size_t datasize, enum OID *oid)
> An exported function without kdoc.
>
>> +{
>> + const unsigned char *v = data;
>> +
>> + if (datasize < 2 || v[0] != ASN1_OID || v[1] != datasize - 2)
>> + return -EBADMSG;
> '1' and '2' are magic numbers unless you either have constants defining
> them, or at least an inline comment with explanation.


I can add those.


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