1 files changed, 145 insertions, 87 deletions

diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
index 06007f0..f83300b 100644
--- a/crypto/asymmetric_keys/x509_public_key.c
+++ b/crypto/asymmetric_keys/x509_public_key.c
@@ -18,85 +18,162 @@
 #include <linux/asn1_decoder.h>
 #include <keys/asymmetric-subtype.h>
 #include <keys/asymmetric-parser.h>
+#include <keys/system_keyring.h>
 #include <crypto/hash.h>
 #include "asymmetric_keys.h"
 #include "public_key.h"
 #include "x509_parser.h"
 
-static const
-struct public_key_algorithm *x509_public_key_algorithms[PKEY_ALGO__LAST] = {
-	[PKEY_ALGO_DSA]		= NULL,
-#if defined(CONFIG_PUBLIC_KEY_ALGO_RSA) || \
-	defined(CONFIG_PUBLIC_KEY_ALGO_RSA_MODULE)
-	[PKEY_ALGO_RSA]		= &RSA_public_key_algorithm,
-#endif
-};
+/*
+ * Find a key in the given keyring by issuer and authority.
+ */
+static struct key *x509_request_asymmetric_key(
+	struct key *keyring,
+	const char *signer, size_t signer_len,
+	const char *authority, size_t auth_len)
+{
+	key_ref_t key;
+	char *id;
+
+	/* Construct an identifier. */
+	id = kmalloc(signer_len + 2 + auth_len + 1, GFP_KERNEL);
+	if (!id)
+		return ERR_PTR(-ENOMEM);
+
+	memcpy(id, signer, signer_len);
+	id[signer_len + 0] = ':';
+	id[signer_len + 1] = ' ';
+	memcpy(id + signer_len + 2, authority, auth_len);
+	id[signer_len + 2 + auth_len] = 0;
+
+	pr_debug("Look up: \"%s\"\n", id);
+
+	key = keyring_search(make_key_ref(keyring, 1),
+			     &key_type_asymmetric, id);
+	if (IS_ERR(key))
+		pr_debug("Request for module key '%s' err %ld\n",
+			 id, PTR_ERR(key));
+	kfree(id);
+
+	if (IS_ERR(key)) {
+		switch (PTR_ERR(key)) {
+			/* Hide some search errors */
+		case -EACCES:
+		case -ENOTDIR:
+		case -EAGAIN:
+			return ERR_PTR(-ENOKEY);
+		default:
+			return ERR_CAST(key);
+		}
+	}
+
+	pr_devel("<==%s() = 0 [%x]\n", __func__, key_serial(key_ref_to_ptr(key)));
+	return key_ref_to_ptr(key);
+}
 
 /*
- * Check the signature on a certificate using the provided public key
+ * Set up the signature parameters in an X.509 certificate.  This involves
+ * digesting the signed data and extracting the signature.
  */
-static int x509_check_signature(const struct public_key *pub,
-				const struct x509_certificate *cert)
+int x509_get_sig_params(struct x509_certificate *cert)
 {
-	struct public_key_signature *sig;
 	struct crypto_shash *tfm;
 	struct shash_desc *desc;
 	size_t digest_size, desc_size;
+	void *digest;
 	int ret;
 
 	pr_devel("==>%s()\n", __func__);
-	
+
+	if (cert->sig.rsa.s)
+		return 0;
+
+	cert->sig.rsa.s = mpi_read_raw_data(cert->raw_sig, cert->raw_sig_size);
+	if (!cert->sig.rsa.s)
+		return -ENOMEM;
+	cert->sig.nr_mpi = 1;
+
 	/* Allocate the hashing algorithm we're going to need and find out how
 	 * big the hash operational data will be.
 	 */
-	tfm = crypto_alloc_shash(pkey_hash_algo[cert->sig_hash_algo], 0, 0);
+	tfm = crypto_alloc_shash(hash_algo_name[cert->sig.pkey_hash_algo], 0, 0);
 	if (IS_ERR(tfm))
 		return (PTR_ERR(tfm) == -ENOENT) ? -ENOPKG : PTR_ERR(tfm);
 
 	desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
 	digest_size = crypto_shash_digestsize(tfm);
 
-	/* We allocate the hash operational data storage on the end of our
-	 * context data.
+	/* We allocate the hash operational data storage on the end of the
+	 * digest storage space.
 	 */
 	ret = -ENOMEM;
-	sig = kzalloc(sizeof(*sig) + desc_size + digest_size, GFP_KERNEL);
-	if (!sig)
-		goto error_no_sig;
+	digest = kzalloc(digest_size + desc_size, GFP_KERNEL);
+	if (!digest)
+		goto error;
 
-	sig->pkey_hash_algo	= cert->sig_hash_algo;
-	sig->digest		= (u8 *)sig + sizeof(*sig) + desc_size;
-	sig->digest_size	= digest_size;
+	cert->sig.digest = digest;
+	cert->sig.digest_size = digest_size;
 
-	desc = (void *)sig + sizeof(*sig);
-	desc->tfm	= tfm;
-	desc->flags	= CRYPTO_TFM_REQ_MAY_SLEEP;
+	desc = digest + digest_size;
+	desc->tfm = tfm;
+	desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 
 	ret = crypto_shash_init(desc);
 	if (ret < 0)
 		goto error;
+	might_sleep();
+	ret = crypto_shash_finup(desc, cert->tbs, cert->tbs_size, digest);
+error:
+	crypto_free_shash(tfm);
+	pr_devel("<==%s() = %d\n", __func__, ret);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(x509_get_sig_params);
 
-	ret = -ENOMEM;
-	sig->rsa.s = mpi_read_raw_data(cert->sig, cert->sig_size);
-	if (!sig->rsa.s)
-		goto error;
+/*
+ * Check the signature on a certificate using the provided public key
+ */
+int x509_check_signature(const struct public_key *pub,
+			 struct x509_certificate *cert)
+{
+	int ret;
 
-	ret = crypto_shash_finup(desc, cert->tbs, cert->tbs_size, sig->digest);
-	if (ret < 0)
-		goto error_mpi;
+	pr_devel("==>%s()\n", __func__);
 
-	ret = pub->algo->verify_signature(pub, sig);
+	ret = x509_get_sig_params(cert);
+	if (ret < 0)
+		return ret;
 
+	ret = public_key_verify_signature(pub, &cert->sig);
 	pr_debug("Cert Verification: %d\n", ret);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(x509_check_signature);
 
-error_mpi:
-	mpi_free(sig->rsa.s);
-error:
-	kfree(sig);
-error_no_sig:
-	crypto_free_shash(tfm);
+/*
+ * Check the new certificate against the ones in the trust keyring.  If one of
+ * those is the signing key and validates the new certificate, then mark the
+ * new certificate as being trusted.
+ *
+ * Return 0 if the new certificate was successfully validated, 1 if we couldn't
+ * find a matching parent certificate in the trusted list and an error if there
+ * is a matching certificate but the signature check fails.
+ */
+static int x509_validate_trust(struct x509_certificate *cert,
+			       struct key *trust_keyring)
+{
+	const struct public_key *pk;
+	struct key *key;
+	int ret = 1;
 
-	pr_devel("<==%s() = %d\n", __func__, ret);
+	key = x509_request_asymmetric_key(trust_keyring,
+					  cert->issuer, strlen(cert->issuer),
+					  cert->authority,
+					  strlen(cert->authority));
+	if (!IS_ERR(key))  {
+		pk = key->payload.data;
+		ret = x509_check_signature(pk, cert);
+	}
 	return ret;
 }
 
@@ -106,7 +183,6 @@ error_no_sig:
 static int x509_key_preparse(struct key_preparsed_payload *prep)
 {
 	struct x509_certificate *cert;
-	struct tm now;
 	size_t srlen, sulen;
 	char *desc = NULL;
 	int ret;
@@ -117,7 +193,18 @@ static int x509_key_preparse(struct key_preparsed_payload *prep)
 
 	pr_devel("Cert Issuer: %s\n", cert->issuer);
 	pr_devel("Cert Subject: %s\n", cert->subject);
-	pr_devel("Cert Key Algo: %s\n", pkey_algo[cert->pkey_algo]);
+
+	if (cert->pub->pkey_algo >= PKEY_ALGO__LAST ||
+	    cert->sig.pkey_algo >= PKEY_ALGO__LAST ||
+	    cert->sig.pkey_hash_algo >= PKEY_HASH__LAST ||
+	    !pkey_algo[cert->pub->pkey_algo] ||
+	    !pkey_algo[cert->sig.pkey_algo] ||
+	    !hash_algo_name[cert->sig.pkey_hash_algo]) {
+		ret = -ENOPKG;
+		goto error_free_cert;
+	}
+
+	pr_devel("Cert Key Algo: %s\n", pkey_algo_name[cert->pub->pkey_algo]);
 	pr_devel("Cert Valid From: %04ld-%02d-%02d %02d:%02d:%02d\n",
 		 cert->valid_from.tm_year + 1900, cert->valid_from.tm_mon + 1,
 		 cert->valid_from.tm_mday, cert->valid_from.tm_hour,
@@ -127,61 +214,29 @@ static int x509_key_preparse(struct key_preparsed_payload *prep)
 		 cert->valid_to.tm_mday, cert->valid_to.tm_hour,
 		 cert->valid_to.tm_min,  cert->valid_to.tm_sec);
 	pr_devel("Cert Signature: %s + %s\n",
-		 pkey_algo[cert->sig_pkey_algo],
-		 pkey_hash_algo[cert->sig_hash_algo]);
+		 pkey_algo_name[cert->sig.pkey_algo],
+		 hash_algo_name[cert->sig.pkey_hash_algo]);
 
-	if (!cert->fingerprint || !cert->authority) {
-		pr_warn("Cert for '%s' must have SubjKeyId and AuthKeyId extensions\n",
+	if (!cert->fingerprint) {
+		pr_warn("Cert for '%s' must have a SubjKeyId extension\n",
 			cert->subject);
 		ret = -EKEYREJECTED;
 		goto error_free_cert;
 	}
 
-	time_to_tm(CURRENT_TIME.tv_sec, 0, &now);
-	pr_devel("Now: %04ld-%02d-%02d %02d:%02d:%02d\n",
-		 now.tm_year + 1900, now.tm_mon + 1, now.tm_mday,
-		 now.tm_hour, now.tm_min,  now.tm_sec);
-	if (now.tm_year < cert->valid_from.tm_year ||
-	    (now.tm_year == cert->valid_from.tm_year &&
-	     (now.tm_mon < cert->valid_from.tm_mon ||
-	      (now.tm_mon == cert->valid_from.tm_mon &&
-	       (now.tm_mday < cert->valid_from.tm_mday ||
-		(now.tm_mday == cert->valid_from.tm_mday &&
-		 (now.tm_hour < cert->valid_from.tm_hour ||
-		  (now.tm_hour == cert->valid_from.tm_hour &&
-		   (now.tm_min < cert->valid_from.tm_min ||
-		    (now.tm_min == cert->valid_from.tm_min &&
-		     (now.tm_sec < cert->valid_from.tm_sec
-		      ))))))))))) {
-		pr_warn("Cert %s is not yet valid\n", cert->fingerprint);
-		ret = -EKEYREJECTED;
-		goto error_free_cert;
-	}
-	if (now.tm_year > cert->valid_to.tm_year ||
-	    (now.tm_year == cert->valid_to.tm_year &&
-	     (now.tm_mon > cert->valid_to.tm_mon ||
-	      (now.tm_mon == cert->valid_to.tm_mon &&
-	       (now.tm_mday > cert->valid_to.tm_mday ||
-		(now.tm_mday == cert->valid_to.tm_mday &&
-		 (now.tm_hour > cert->valid_to.tm_hour ||
-		  (now.tm_hour == cert->valid_to.tm_hour &&
-		   (now.tm_min > cert->valid_to.tm_min ||
-		    (now.tm_min == cert->valid_to.tm_min &&
-		     (now.tm_sec > cert->valid_to.tm_sec
-		      ))))))))))) {
-		pr_warn("Cert %s has expired\n", cert->fingerprint);
-		ret = -EKEYEXPIRED;
-		goto error_free_cert;
-	}
-
-	cert->pub->algo = x509_public_key_algorithms[cert->pkey_algo];
+	cert->pub->algo = pkey_algo[cert->pub->pkey_algo];
 	cert->pub->id_type = PKEY_ID_X509;
 
-	/* Check the signature on the key */
-	if (strcmp(cert->fingerprint, cert->authority) == 0) {
-		ret = x509_check_signature(cert->pub, cert);
+	/* Check the signature on the key if it appears to be self-signed */
+	if (!cert->authority ||
+	    strcmp(cert->fingerprint, cert->authority) == 0) {
+		ret = x509_check_signature(cert->pub, cert); /* self-signed */
 		if (ret < 0)
 			goto error_free_cert;
+	} else {
+		ret = x509_validate_trust(cert, system_trusted_keyring);
+		if (!ret)
+			prep->trusted = 1;
 	}
 
 	/* Propose a description */
@@ -237,3 +292,6 @@ static void __exit x509_key_exit(void)
 
 module_init(x509_key_init);
 module_exit(x509_key_exit);
+
+MODULE_DESCRIPTION("X.509 certificate parser");
+MODULE_LICENSE("GPL");