We only support PKCS#7 signed-data [RFC2315 sec 9] content at the top level,
so reject anything else. Further, check that the version numbers in
SignedData and SignerInfo are 1 in both cases.
Note that we don't restrict the inner content type. In the PKCS#7 code we
don't parse the data attached there, but merely verify the signature over
it.
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Reviewed-By: David Woodhouse <David.Woodhouse@xxxxxxxxx>
---
crypto/asymmetric_keys/pkcs7.asn1 | 6 +--
crypto/asymmetric_keys/pkcs7_parser.c | 75 +++++++++++++++++++++++++++++++++
2 files changed, 77 insertions(+), 4 deletions(-)
diff --git a/crypto/asymmetric_keys/pkcs7.asn1 b/crypto/asymmetric_keys/pkcs7.asn1
index a5a14ef28c86..05504431e1c1 100644
--- a/crypto/asymmetric_keys/pkcs7.asn1
+++ b/crypto/asymmetric_keys/pkcs7.asn1
@@ -1,12 +1,12 @@
PKCS7ContentInfo ::= SEQUENCE {
- contentType ContentType,
+ contentType ContentType ({ pkcs7_check_content_type }),
content [0] EXPLICIT SignedData OPTIONAL
}
ContentType ::= OBJECT IDENTIFIER ({ pkcs7_note_OID })
SignedData ::= SEQUENCE {
- version INTEGER,
+ version INTEGER ({ pkcs7_note_signeddata_version }),
digestAlgorithms DigestAlgorithmIdentifiers,
contentInfo ContentInfo,
certificates CHOICE {
@@ -68,7 +68,7 @@ SignerInfos ::= CHOICE {
}
SignerInfo ::= SEQUENCE {
- version INTEGER,
+ version INTEGER ({ pkcs7_note_signerinfo_version }),
issuerAndSerialNumber IssuerAndSerialNumber,
digestAlgorithm DigestAlgorithmIdentifier ({ pkcs7_sig_note_digest_algo }),
authenticatedAttributes CHOICE {
diff --git a/crypto/asymmetric_keys/pkcs7_parser.c b/crypto/asymmetric_keys/pkcs7_parser.c
index 3bd5a1e4c493..ab427f04b299 100644
--- a/crypto/asymmetric_keys/pkcs7_parser.c
+++ b/crypto/asymmetric_keys/pkcs7_parser.c
@@ -226,6 +226,79 @@ int pkcs7_sig_note_pkey_algo(void *context, size_t hdrlen,
}
/*
+ * We only support signed data [RFC2315 sec 9].
+ */
+int pkcs7_check_content_type(void *context, size_t hdrlen,
+ unsigned char tag,
+ const void *value, size_t vlen)
+{
+ struct pkcs7_parse_context *ctx = context;
+
+ if (ctx->last_oid != OID_signed_data) {
+ pr_warn("Only support pkcs7_signedData type\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+/*
+ * Note the SignedData version
+ */
+int pkcs7_note_signeddata_version(void *context, size_t hdrlen,
+ unsigned char tag,
+ const void *value, size_t vlen)
+{
+ unsigned version;
+
+ if (vlen != 1)
+ goto unsupported;
+
+ version = *(const u8 *)value;
+ switch (version) {
+ case 1:
+ /* PKCS#7 SignedData [RFC2315 sec 9.1] */
+ break;
+ default:
+ goto unsupported;
+ }
+
+ return 0;
+
+unsupported:
+ pr_warn("Unsupported SignedData version\n");
+ return -EINVAL;
+}
+
+/*
+ * Note the SignerInfo version
+ */
+int pkcs7_note_signerinfo_version(void *context, size_t hdrlen,
+ unsigned char tag,
+ const void *value, size_t vlen)
+{
+ unsigned version;
+
+ if (vlen != 1)
+ goto unsupported;
+
+ version = *(const u8 *)value;
+ switch (version) {
+ case 1:
+ /* PKCS#7 SignerInfo [RFC2315 sec 9.2] */
+ break;
+ default:
+ goto unsupported;
+ }
+
+ return 0;
+
+unsupported:
+ pr_warn("Unsupported SignerInfo version\n");
+ return -EINVAL;
+}
+
+/*
* Extract a certificate and store it in the context.
*/
int pkcs7_extract_cert(void *context, size_t hdrlen,
@@ -326,7 +399,7 @@ int pkcs7_sig_note_authenticated_attr(void *context, size_t hdrlen,
}
/*
- * Note the set of auth attributes for digestion purposes [RFC2315 9.3]
+ * Note the set of auth attributes for digestion purposes [RFC2315 sec 9.3]
*/
int pkcs7_sig_note_set_of_authattrs(void *context, size_t hdrlen,
unsigned char tag,
--
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