1 files changed, 71 insertions, 31 deletions

diff --git a/crypto/asymmetric_keys/pkcs7_verify.c b/crypto/asymmetric_keys/pkcs7_verify.c
index c62cf8006e1f..cd455450b069 100644
--- a/crypto/asymmetric_keys/pkcs7_verify.c
+++ b/crypto/asymmetric_keys/pkcs7_verify.c
@@ -131,8 +131,7 @@ static int pkcs7_find_key(struct pkcs7_message *pkcs7,
 	struct x509_certificate *x509;
 	unsigned certix = 1;
 
-	kenter("%u,%u,%u",
-	       sinfo->index, sinfo->raw_serial_size, sinfo->raw_issuer_size);
+	kenter("%u", sinfo->index);
 
 	for (x509 = pkcs7->certs; x509; x509 = x509->next, certix++) {
 		/* I'm _assuming_ that the generator of the PKCS#7 message will
@@ -140,21 +139,11 @@ static int pkcs7_find_key(struct pkcs7_message *pkcs7,
 		 * PKCS#7 message - but I can't be 100% sure of that.  It's
 		 * possible this will need element-by-element comparison.
 		 */
-		if (x509->raw_serial_size != sinfo->raw_serial_size ||
-		    memcmp(x509->raw_serial, sinfo->raw_serial,
-			   sinfo->raw_serial_size) != 0)
+		if (!asymmetric_key_id_same(x509->id, sinfo->signing_cert_id))
 			continue;
 		pr_devel("Sig %u: Found cert serial match X.509[%u]\n",
 			 sinfo->index, certix);
 
-		if (x509->raw_issuer_size != sinfo->raw_issuer_size ||
-		    memcmp(x509->raw_issuer, sinfo->raw_issuer,
-			   sinfo->raw_issuer_size) != 0) {
-			pr_warn("Sig %u: X.509 subject and PKCS#7 issuer don't match\n",
-				sinfo->index);
-			continue;
-		}
-
 		if (x509->pub->pkey_algo != sinfo->sig.pkey_algo) {
 			pr_warn("Sig %u: X.509 algo and PKCS#7 sig algo don't match\n",
 				sinfo->index);
@@ -164,9 +153,14 @@ static int pkcs7_find_key(struct pkcs7_message *pkcs7,
 		sinfo->signer = x509;
 		return 0;
 	}
-	pr_warn("Sig %u: Issuing X.509 cert not found (#%*ph)\n",
-		sinfo->index, sinfo->raw_serial_size, sinfo->raw_serial);
-	return -ENOKEY;
+
+	/* The relevant X.509 cert isn't found here, but it might be found in
+	 * the trust keyring.
+	 */
+	pr_debug("Sig %u: Issuing X.509 cert not found (#%*phN)\n",
+		 sinfo->index,
+		 sinfo->signing_cert_id->len, sinfo->signing_cert_id->data);
+	return 0;
 }
 
 /*
@@ -184,15 +178,18 @@ static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7,
 		p->seen = false;
 
 	for (;;) {
-		pr_debug("verify %s: %s\n", x509->subject, x509->fingerprint);
+		pr_debug("verify %s: %*phN\n",
+			 x509->subject,
+			 x509->raw_serial_size, x509->raw_serial);
 		x509->seen = true;
 		ret = x509_get_sig_params(x509);
 		if (ret < 0)
-			return ret;
+			goto maybe_missing_crypto_in_x509;
 
 		pr_debug("- issuer %s\n", x509->issuer);
 		if (x509->authority)
-			pr_debug("- authkeyid %s\n", x509->authority);
+			pr_debug("- authkeyid %*phN\n",
+				 x509->authority->len, x509->authority->data);
 
 		if (!x509->authority ||
 		    strcmp(x509->subject, x509->issuer) == 0) {
@@ -209,7 +206,7 @@ static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7,
 
 			ret = x509_check_signature(x509->pub, x509);
 			if (ret < 0)
-				return ret;
+				goto maybe_missing_crypto_in_x509;
 			x509->signer = x509;
 			pr_debug("- self-signed\n");
 			return 0;
@@ -218,13 +215,14 @@ static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7,
 		/* Look through the X.509 certificates in the PKCS#7 message's
 		 * list to see if the next one is there.
 		 */
-		pr_debug("- want %s\n", x509->authority);
+		pr_debug("- want %*phN\n",
+			 x509->authority->len, x509->authority->data);
 		for (p = pkcs7->certs; p; p = p->next) {
-			pr_debug("- cmp [%u] %s\n", p->index, p->fingerprint);
-			if (p->raw_subject_size == x509->raw_issuer_size &&
-			    strcmp(p->fingerprint, x509->authority) == 0 &&
-			    memcmp(p->raw_subject, x509->raw_issuer,
-				   x509->raw_issuer_size) == 0)
+			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))
 				goto found_issuer;
 		}
 
@@ -233,7 +231,7 @@ static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7,
 		return 0;
 
 	found_issuer:
-		pr_debug("- issuer %s\n", p->subject);
+		pr_debug("- subject %s\n", p->subject);
 		if (p->seen) {
 			pr_warn("Sig %u: X.509 chain contains loop\n",
 				sinfo->index);
@@ -250,6 +248,17 @@ static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7,
 		x509 = p;
 		might_sleep();
 	}
+
+maybe_missing_crypto_in_x509:
+	/* Just prune the certificate chain at this point if we lack some
+	 * crypto module to go further.  Note, however, we don't want to set
+	 * sinfo->missing_crypto as the signed info block may still be
+	 * validatable against an X.509 cert lower in the chain that we have a
+	 * trusted copy of.
+	 */
+	if (ret == -ENOPKG)
+		return 0;
+	return ret;
 }
 
 /*
@@ -269,11 +278,14 @@ static int pkcs7_verify_one(struct pkcs7_message *pkcs7,
 	if (ret < 0)
 		return ret;
 
-	/* Find the key for the signature */
+	/* Find the key for the signature if there is one */
 	ret = pkcs7_find_key(pkcs7, sinfo);
 	if (ret < 0)
 		return ret;
 
+	if (!sinfo->signer)
+		return 0;
+
 	pr_devel("Using X.509[%u] for sig %u\n",
 		 sinfo->signer->index, sinfo->index);
 
@@ -291,11 +303,33 @@ static int pkcs7_verify_one(struct pkcs7_message *pkcs7,
 /**
  * pkcs7_verify - Verify a PKCS#7 message
  * @pkcs7: The PKCS#7 message to be verified
+ *
+ * Verify a PKCS#7 message is internally consistent - that is, the data digest
+ * matches the digest in the AuthAttrs and any signature in the message or one
+ * of the X.509 certificates it carries that matches another X.509 cert in the
+ * message can be verified.
+ *
+ * This does not look to match the contents of the PKCS#7 message against any
+ * external public keys.
+ *
+ * Returns, in order of descending priority:
+ *
+ *  (*) -EKEYREJECTED if a signature failed to match for which we found an
+ *	appropriate X.509 certificate, or:
+ *
+ *  (*) -EBADMSG if some part of the message was invalid, or:
+ *
+ *  (*) -ENOPKG if none of the signature chains are verifiable because suitable
+ *	crypto modules couldn't be found, or:
+ *
+ *  (*) 0 if all the signature chains that don't incur -ENOPKG can be verified
+ *	(note that a signature chain may be of zero length), or:
  */
 int pkcs7_verify(struct pkcs7_message *pkcs7)
 {
 	struct pkcs7_signed_info *sinfo;
 	struct x509_certificate *x509;
+	int enopkg = -ENOPKG;
 	int ret, n;
 
 	kenter("");
@@ -304,18 +338,24 @@ int pkcs7_verify(struct pkcs7_message *pkcs7)
 		ret = x509_get_sig_params(x509);
 		if (ret < 0)
 			return ret;
-		pr_debug("X.509[%u] %s\n", n, x509->authority);
+		pr_debug("X.509[%u] %*phN\n",
+			 n, x509->authority->len, x509->authority->data);
 	}
 
 	for (sinfo = pkcs7->signed_infos; sinfo; sinfo = sinfo->next) {
 		ret = pkcs7_verify_one(pkcs7, sinfo);
 		if (ret < 0) {
+			if (ret == -ENOPKG) {
+				sinfo->unsupported_crypto = true;
+				continue;
+			}
 			kleave(" = %d", ret);
 			return ret;
 		}
+		enopkg = 0;
 	}
 
-	kleave(" = 0");
-	return 0;
+	kleave(" = %d", enopkg);
+	return enopkg;
 }
 EXPORT_SYMBOL_GPL(pkcs7_verify);