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x509: Detect sm2 keys by their parameters OID
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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 <[email protected]>
Cc: [email protected]
Signed-off-by: Stefan Berger <[email protected]>
Reviewed-by: Tianjia Zhang <[email protected]>
Tested-by: Tianjia Zhang <[email protected]>
Signed-off-by: Herbert Xu <[email protected]>
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stefanberger authored and herbertx committed Mar 26, 2021
1 parent c12d448 commit d1a303e
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Showing 3 changed files with 36 additions and 1 deletion.
12 changes: 11 additions & 1 deletion crypto/asymmetric_keys/x509_cert_parser.c
Original file line number Diff line number Diff line change
Expand Up @@ -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;

ctx->key_algo = ctx->last_oid;
switch (ctx->last_oid) {
Expand All @@ -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;
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1 change: 1 addition & 0 deletions include/linux/oid_registry.h
Original file line number Diff line number Diff line change
Expand Up @@ -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);

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24 changes: 24 additions & 0 deletions lib/oid_registry.c
Original file line number Diff line number Diff line change
Expand Up @@ -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");
Expand Down Expand Up @@ -92,6 +93,29 @@ enum OID look_up_OID(const void *data, size_t datasize)
}
EXPORT_SYMBOL_GPL(look_up_OID);

/**
* parse_OID - Parse an OID from a bytestream
* @data: Binary representation of the header + OID
* @datasize: Size of the binary representation
* @oid: Pointer to oid to return result
*
* Parse an OID from a bytestream that holds the OID in the format
* ASN1_OID | length | oid. The length indicator must equal to datasize - 2.
* -EBADMSG is returned if the bytestream is too short.
*/
int parse_OID(const void *data, size_t datasize, enum OID *oid)
{
const unsigned char *v = data;

/* we need 2 bytes of header and at least 1 byte for oid */
if (datasize < 3 || v[0] != ASN1_OID || v[1] != datasize - 2)
return -EBADMSG;

*oid = look_up_OID(data + 2, datasize - 2);
return 0;
}
EXPORT_SYMBOL_GPL(parse_OID);

/*
* sprint_OID - Print an Object Identifier into a buffer
* @data: The encoded OID to print
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