[PATCH 03/27] X.509: Extract both parts of the AuthorityKeyIdentifier [ver #7]

From: David Howells
Date: Wed Aug 05 2015 - 09:57:18 EST

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Extract both parts of the AuthorityKeyIdentifier, not just the keyIdentifier,
as the second part can be used to match X.509 certificates by issuer and
serialNumber.

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Tested-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
---

crypto/asymmetric_keys/Makefile | 8 +-
crypto/asymmetric_keys/pkcs7_trust.c | 4 -
crypto/asymmetric_keys/pkcs7_verify.c | 12 +-
crypto/asymmetric_keys/x509_akid.asn1 | 35 +++++++
crypto/asymmetric_keys/x509_cert_parser.c | 142 ++++++++++++++++++-----------
crypto/asymmetric_keys/x509_parser.h | 5 +
crypto/asymmetric_keys/x509_public_key.c | 8 +-
7 files changed, 145 insertions(+), 69 deletions(-)
create mode 100644 crypto/asymmetric_keys/x509_akid.asn1

diff --git a/crypto/asymmetric_keys/Makefile b/crypto/asymmetric_keys/Makefile
index e47fcd9ac5e8..cd1406f9b14a 100644
--- a/crypto/asymmetric_keys/Makefile
+++ b/crypto/asymmetric_keys/Makefile
@@ -15,15 +15,21 @@ obj-$(CONFIG_PUBLIC_KEY_ALGO_RSA) += rsa.o
obj-$(CONFIG_X509_CERTIFICATE_PARSER) += x509_key_parser.o
x509_key_parser-y := \
x509-asn1.o \
+ x509_akid-asn1.o \
x509_rsakey-asn1.o \
x509_cert_parser.o \
x509_public_key.o

-$(obj)/x509_cert_parser.o: $(obj)/x509-asn1.h $(obj)/x509_rsakey-asn1.h
+$(obj)/x509_cert_parser.o: \
+ $(obj)/x509-asn1.h \
+ $(obj)/x509_akid-asn1.h \
+ $(obj)/x509_rsakey-asn1.h
$(obj)/x509-asn1.o: $(obj)/x509-asn1.c $(obj)/x509-asn1.h
+$(obj)/x509_akid-asn1.o: $(obj)/x509_akid-asn1.c $(obj)/x509_akid-asn1.h
$(obj)/x509_rsakey-asn1.o: $(obj)/x509_rsakey-asn1.c $(obj)/x509_rsakey-asn1.h

clean-files += x509-asn1.c x509-asn1.h
+clean-files += x509_akid-asn1.c x509_akid-asn1.h
clean-files += x509_rsakey-asn1.c x509_rsakey-asn1.h

#
diff --git a/crypto/asymmetric_keys/pkcs7_trust.c b/crypto/asymmetric_keys/pkcs7_trust.c
index 1d29376072da..0f6463b6692b 100644
--- a/crypto/asymmetric_keys/pkcs7_trust.c
+++ b/crypto/asymmetric_keys/pkcs7_trust.c
@@ -85,8 +85,8 @@ static int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7,
/* No match - see if the root certificate has a signer amongst the
* trusted keys.
*/
- if (last && last->authority) {
- key = x509_request_asymmetric_key(trust_keyring, last->authority,
+ if (last && last->akid_skid) {
+ key = x509_request_asymmetric_key(trust_keyring, last->akid_skid,
false);
if (!IS_ERR(key)) {
x509 = last;
diff --git a/crypto/asymmetric_keys/pkcs7_verify.c b/crypto/asymmetric_keys/pkcs7_verify.c
index cd455450b069..a4d083f7e9e1 100644
--- a/crypto/asymmetric_keys/pkcs7_verify.c
+++ b/crypto/asymmetric_keys/pkcs7_verify.c
@@ -187,11 +187,11 @@ static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7,
goto maybe_missing_crypto_in_x509;

pr_debug("- issuer %s\n", x509->issuer);
- if (x509->authority)
+ if (x509->akid_skid)
pr_debug("- authkeyid %*phN\n",
- x509->authority->len, x509->authority->data);
+ x509->akid_skid->len, x509->akid_skid->data);

- if (!x509->authority ||
+ if (!x509->akid_skid ||
strcmp(x509->subject, x509->issuer) == 0) {
/* If there's no authority certificate specified, then
* the certificate must be self-signed and is the root
@@ -216,13 +216,13 @@ static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7,
* list to see if the next one is there.
*/
pr_debug("- want %*phN\n",
- x509->authority->len, x509->authority->data);
+ x509->akid_skid->len, x509->akid_skid->data);
for (p = pkcs7->certs; p; p = p->next) {
if (!p->skid)
continue;
pr_debug("- cmp [%u] %*phN\n",
p->index, p->skid->len, p->skid->data);
- if (asymmetric_key_id_same(p->skid, x509->authority))
+ if (asymmetric_key_id_same(p->skid, x509->akid_skid))
goto found_issuer;
}

@@ -338,8 +338,6 @@ int pkcs7_verify(struct pkcs7_message *pkcs7)
ret = x509_get_sig_params(x509);
if (ret < 0)
return ret;
- pr_debug("X.509[%u] %*phN\n",
- n, x509->authority->len, x509->authority->data);
}

for (sinfo = pkcs7->signed_infos; sinfo; sinfo = sinfo->next) {
diff --git a/crypto/asymmetric_keys/x509_akid.asn1 b/crypto/asymmetric_keys/x509_akid.asn1
new file mode 100644
index 000000000000..1a33231a75a8
--- /dev/null
+++ b/crypto/asymmetric_keys/x509_akid.asn1
@@ -0,0 +1,35 @@
+-- X.509 AuthorityKeyIdentifier
+-- rfc5280 section 4.2.1.1
+
+AuthorityKeyIdentifier ::= SEQUENCE {
+ keyIdentifier [0] IMPLICIT KeyIdentifier OPTIONAL,
+ authorityCertIssuer [1] IMPLICIT GeneralNames OPTIONAL,
+ authorityCertSerialNumber [2] IMPLICIT CertificateSerialNumber OPTIONAL
+ }
+
+KeyIdentifier ::= OCTET STRING ({ x509_akid_note_kid })
+
+CertificateSerialNumber ::= INTEGER ({ x509_akid_note_serial })
+
+GeneralNames ::= SEQUENCE OF GeneralName
+
+GeneralName ::= CHOICE {
+ otherName [0] ANY,
+ rfc822Name [1] IA5String,
+ dNSName [2] IA5String,
+ x400Address [3] ANY,
+ directoryName [4] Name ({ x509_akid_note_name }),
+ ediPartyName [5] ANY,
+ uniformResourceIdentifier [6] IA5String,
+ iPAddress [7] OCTET STRING,
+ registeredID [8] OBJECT IDENTIFIER
+ }
+
+Name ::= SEQUENCE OF RelativeDistinguishedName
+
+RelativeDistinguishedName ::= SET OF AttributeValueAssertion
+
+AttributeValueAssertion ::= SEQUENCE {
+ attributeType OBJECT IDENTIFIER ({ x509_note_OID }),
+ attributeValue ANY ({ x509_extract_name_segment })
+ }
diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
index a668d90302d3..6c130dd56f35 100644
--- a/crypto/asymmetric_keys/x509_cert_parser.c
+++ b/crypto/asymmetric_keys/x509_cert_parser.c
@@ -18,6 +18,7 @@
#include "public_key.h"
#include "x509_parser.h"
#include "x509-asn1.h"
+#include "x509_akid-asn1.h"
#include "x509_rsakey-asn1.h"

struct x509_parse_context {
@@ -35,6 +36,10 @@ struct x509_parse_context {
u16 o_offset; /* Offset of organizationName (O) */
u16 cn_offset; /* Offset of commonName (CN) */
u16 email_offset; /* Offset of emailAddress */
+ unsigned raw_akid_size;
+ const void *raw_akid; /* Raw authorityKeyId in ASN.1 */
+ const void *akid_raw_issuer; /* Raw directoryName in authorityKeyId */
+ unsigned akid_raw_issuer_size;
};

/*
@@ -48,7 +53,8 @@ void x509_free_certificate(struct x509_certificate *cert)
kfree(cert->subject);
kfree(cert->id);
kfree(cert->skid);
- kfree(cert->authority);
+ kfree(cert->akid_id);
+ kfree(cert->akid_skid);
kfree(cert->sig.digest);
mpi_free(cert->sig.rsa.s);
kfree(cert);
@@ -85,6 +91,18 @@ struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
if (ret < 0)
goto error_decode;

+ /* Decode the AuthorityKeyIdentifier */
+ if (ctx->raw_akid) {
+ pr_devel("AKID: %u %*phN\n",
+ ctx->raw_akid_size, ctx->raw_akid_size, ctx->raw_akid);
+ ret = asn1_ber_decoder(&x509_akid_decoder, ctx,
+ ctx->raw_akid, ctx->raw_akid_size);
+ if (ret < 0) {
+ pr_warn("Couldn't decode AuthKeyIdentifier\n");
+ goto error_decode;
+ }
+ }
+
/* Decode the public key */
ret = asn1_ber_decoder(&x509_rsakey_decoder, ctx,
ctx->key, ctx->key_size);
@@ -422,7 +440,6 @@ int x509_process_extension(void *context, size_t hdrlen,
struct x509_parse_context *ctx = context;
struct asymmetric_key_id *kid;
const unsigned char *v = value;
- int i;

pr_debug("Extension: %u\n", ctx->last_oid);

@@ -449,57 +466,8 @@ int x509_process_extension(void *context, size_t hdrlen,

if (ctx->last_oid == OID_authorityKeyIdentifier) {
/* Get hold of the CA key fingerprint */
- if (ctx->cert->authority || vlen < 5)
- return -EBADMSG;
-
- /* Authority Key Identifier must be a Constructed SEQUENCE */
- if (v[0] != (ASN1_SEQ | (ASN1_CONS << 5)))
- return -EBADMSG;
-
- /* Authority Key Identifier is not indefinite length */
- if (unlikely(vlen == ASN1_INDEFINITE_LENGTH))
- return -EBADMSG;
-
- if (vlen < ASN1_INDEFINITE_LENGTH) {
- /* Short Form length */
- if (v[1] != vlen - 2 ||
- v[2] != SEQ_TAG_KEYID ||
- v[3] > vlen - 4)
- return -EBADMSG;
-
- vlen = v[3];
- v += 4;
- } else {
- /* Long Form length */
- size_t seq_len = 0;
- size_t sub = v[1] - ASN1_INDEFINITE_LENGTH;
-
- if (sub > 2)
- return -EBADMSG;
-
- /* calculate the length from subsequent octets */
- v += 2;
- for (i = 0; i < sub; i++) {
- seq_len <<= 8;
- seq_len |= v[i];
- }
-
- if (seq_len != vlen - 2 - sub ||
- v[sub] != SEQ_TAG_KEYID ||
- v[sub + 1] > vlen - 4 - sub)
- return -EBADMSG;
-
- vlen = v[sub + 1];
- v += (sub + 2);
- }
-
- kid = asymmetric_key_generate_id(ctx->cert->raw_issuer,
- ctx->cert->raw_issuer_size,
- v, vlen);
- if (IS_ERR(kid))
- return PTR_ERR(kid);
- pr_debug("authkeyid %*phN\n", kid->len, kid->data);
- ctx->cert->authority = kid;
+ ctx->raw_akid = v;
+ ctx->raw_akid_size = vlen;
return 0;
}

@@ -569,3 +537,71 @@ int x509_note_not_after(void *context, size_t hdrlen,
struct x509_parse_context *ctx = context;
return x509_note_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
}
+
+/*
+ * Note a key identifier-based AuthorityKeyIdentifier
+ */
+int x509_akid_note_kid(void *context, size_t hdrlen,
+ unsigned char tag,
+ const void *value, size_t vlen)
+{
+ struct x509_parse_context *ctx = context;
+ struct asymmetric_key_id *kid;
+
+ pr_debug("AKID: keyid: %*phN\n", (int)vlen, value);
+
+ if (ctx->cert->akid_skid)
+ return 0;
+
+ kid = asymmetric_key_generate_id(ctx->cert->raw_issuer,
+ ctx->cert->raw_issuer_size,
+ value, vlen);
+ if (IS_ERR(kid))
+ return PTR_ERR(kid);
+ pr_debug("authkeyid %*phN\n", kid->len, kid->data);
+ ctx->cert->akid_skid = kid;
+ return 0;
+}
+
+/*
+ * Note a directoryName in an AuthorityKeyIdentifier
+ */
+int x509_akid_note_name(void *context, size_t hdrlen,
+ unsigned char tag,
+ const void *value, size_t vlen)
+{
+ struct x509_parse_context *ctx = context;
+
+ pr_debug("AKID: name: %*phN\n", (int)vlen, value);
+
+ ctx->akid_raw_issuer = value;
+ ctx->akid_raw_issuer_size = vlen;
+ return 0;
+}
+
+/*
+ * Note a serial number in an AuthorityKeyIdentifier
+ */
+int x509_akid_note_serial(void *context, size_t hdrlen,
+ unsigned char tag,
+ const void *value, size_t vlen)
+{
+ struct x509_parse_context *ctx = context;
+ struct asymmetric_key_id *kid;
+
+ pr_debug("AKID: serial: %*phN\n", (int)vlen, value);
+
+ if (!ctx->akid_raw_issuer || ctx->cert->akid_id)
+ return 0;
+
+ kid = asymmetric_key_generate_id(value,
+ vlen,
+ ctx->akid_raw_issuer,
+ ctx->akid_raw_issuer_size);
+ if (IS_ERR(kid))
+ return PTR_ERR(kid);
+
+ pr_debug("authkeyid %*phN\n", kid->len, kid->data);
+ ctx->cert->akid_id = kid;
+ return 0;
+}
diff --git a/crypto/asymmetric_keys/x509_parser.h b/crypto/asymmetric_keys/x509_parser.h
index 3dfe6b5d6f0b..dcdb5c94f514 100644
--- a/crypto/asymmetric_keys/x509_parser.h
+++ b/crypto/asymmetric_keys/x509_parser.h
@@ -19,9 +19,10 @@ struct x509_certificate {
struct public_key_signature sig; /* Signature parameters */
char *issuer; /* Name of certificate issuer */
char *subject; /* Name of certificate subject */
- struct asymmetric_key_id *id; /* Serial number + issuer */
+ struct asymmetric_key_id *id; /* Issuer + Serial number */
struct asymmetric_key_id *skid; /* Subject + subjectKeyId (optional) */
- struct asymmetric_key_id *authority; /* Authority key identifier (optional) */
+ struct asymmetric_key_id *akid_id; /* CA AuthKeyId matching ->id (optional) */
+ struct asymmetric_key_id *akid_skid; /* CA AuthKeyId matching ->skid (optional) */
struct tm valid_from;
struct tm valid_to;
const void *tbs; /* Signed data */
diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
index 24f17e6c5904..bb55d6074d5f 100644
--- a/crypto/asymmetric_keys/x509_public_key.c
+++ b/crypto/asymmetric_keys/x509_public_key.c
@@ -227,10 +227,10 @@ static int x509_validate_trust(struct x509_certificate *cert,
if (!trust_keyring)
return -EOPNOTSUPP;

- if (ca_keyid && !asymmetric_key_id_partial(cert->authority, ca_keyid))
+ if (ca_keyid && !asymmetric_key_id_partial(cert->akid_skid, ca_keyid))
return -EPERM;

- key = x509_request_asymmetric_key(trust_keyring, cert->authority,
+ key = x509_request_asymmetric_key(trust_keyring, cert->akid_skid,
false);
if (!IS_ERR(key)) {
if (!use_builtin_keys
@@ -287,8 +287,8 @@ static int x509_key_preparse(struct key_preparsed_payload *prep)
cert->pub->id_type = PKEY_ID_X509;

/* Check the signature on the key if it appears to be self-signed */
- if (!cert->authority ||
- asymmetric_key_id_same(cert->skid, cert->authority)) {
+ if (!cert->akid_skid ||
+ asymmetric_key_id_same(cert->skid, cert->akid_skid)) {
ret = x509_check_signature(cert->pub, cert); /* self-signed */
if (ret < 0)
goto error_free_cert;

--
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Next message: Andrea Parri: "[PATCH 1/2] sched/deadline: fix comment in push_dl_tasks"
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In reply to: David Howells: "[PATCH 09/27] system_keyring.c doesn't need to #include module-internal.h [ver #7]"
Next in thread: David Howells: "Re: [PATCH 25/27] PKCS#7: Appropriately require or forbid authenticated attributes [ver #7]"
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