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Message-ID: <20160108183450.25960.39362.stgit@warthog.procyon.org.uk>
Date: Fri, 08 Jan 2016 18:34:50 +0000
From: David Howells <dhowells@...hat.com>
To: zohar@...ux.vnet.ibm.com
Cc: dhowells@...hat.com, linux-security-module@...r.kernel.org,
keyrings@...r.kernel.org, petkan@...-labs.com,
linux-kernel@...r.kernel.org
Subject: [RFC PATCH 12/15] X.509: Move the trust validation code out to its
own file
Move the X.509 trust validation code out to its own file so that it can be
generalised.
Signed-off-by: David Howells <dhowells@...hat.com>
---
crypto/asymmetric_keys/Makefile | 2
crypto/asymmetric_keys/public_key_trust.c | 195 +++++++++++++++++++++++++++++
crypto/asymmetric_keys/x509_parser.h | 6 +
crypto/asymmetric_keys/x509_public_key.c | 170 -------------------------
4 files changed, 202 insertions(+), 171 deletions(-)
create mode 100644 crypto/asymmetric_keys/public_key_trust.c
diff --git a/crypto/asymmetric_keys/Makefile b/crypto/asymmetric_keys/Makefile
index cd1406f9b14a..3f291bbf7b74 100644
--- a/crypto/asymmetric_keys/Makefile
+++ b/crypto/asymmetric_keys/Makefile
@@ -6,7 +6,7 @@ obj-$(CONFIG_ASYMMETRIC_KEY_TYPE) += asymmetric_keys.o
asymmetric_keys-y := asymmetric_type.o signature.o
-obj-$(CONFIG_ASYMMETRIC_PUBLIC_KEY_SUBTYPE) += public_key.o
+obj-$(CONFIG_ASYMMETRIC_PUBLIC_KEY_SUBTYPE) += public_key.o public_key_trust.o
obj-$(CONFIG_PUBLIC_KEY_ALGO_RSA) += rsa.o
#
diff --git a/crypto/asymmetric_keys/public_key_trust.c b/crypto/asymmetric_keys/public_key_trust.c
new file mode 100644
index 000000000000..9febe612e659
--- /dev/null
+++ b/crypto/asymmetric_keys/public_key_trust.c
@@ -0,0 +1,195 @@
+/* Instantiate a public key crypto key from an X.509 Certificate
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@...hat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#define pr_fmt(fmt) "X.509: "fmt
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/mpi.h>
+#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 bool use_builtin_keys;
+static struct asymmetric_key_id *ca_keyid;
+
+#ifndef MODULE
+static struct {
+ struct asymmetric_key_id id;
+ unsigned char data[10];
+} cakey;
+
+static int __init ca_keys_setup(char *str)
+{
+ if (!str) /* default system keyring */
+ return 1;
+
+ if (strncmp(str, "id:", 3) == 0) {
+ struct asymmetric_key_id *p = &cakey.id;
+ size_t hexlen = (strlen(str) - 3) / 2;
+ int ret;
+
+ if (hexlen == 0 || hexlen > sizeof(cakey.data)) {
+ pr_err("Missing or invalid ca_keys id\n");
+ return 1;
+ }
+
+ ret = __asymmetric_key_hex_to_key_id(str + 3, p, hexlen);
+ if (ret < 0)
+ pr_err("Unparsable ca_keys id hex string\n");
+ else
+ ca_keyid = p; /* owner key 'id:xxxxxx' */
+ } else if (strcmp(str, "builtin") == 0) {
+ use_builtin_keys = true;
+ }
+
+ return 1;
+}
+__setup("ca_keys=", ca_keys_setup);
+#endif
+
+/**
+ * x509_request_asymmetric_key - Request a key by X.509 certificate params.
+ * @keyring: The keys to search.
+ * @id: The issuer & serialNumber to look for or NULL.
+ * @skid: The subjectKeyIdentifier to look for or NULL.
+ * @partial: Use partial match if true, exact if false.
+ *
+ * Find a key in the given keyring by identifier. The preferred identifier is
+ * the issuer + serialNumber and the fallback identifier is the
+ * subjectKeyIdentifier. If both are given, the lookup is by the former, but
+ * the latter must also match.
+ */
+struct key *x509_request_asymmetric_key(struct key *keyring,
+ const struct asymmetric_key_id *id,
+ const struct asymmetric_key_id *skid,
+ bool partial)
+{
+ struct key *key;
+ key_ref_t ref;
+ const char *lookup;
+ char *req, *p;
+ int len;
+
+ if (id) {
+ lookup = id->data;
+ len = id->len;
+ } else {
+ lookup = skid->data;
+ len = skid->len;
+ }
+
+ /* Construct an identifier "id:<keyid>". */
+ p = req = kmalloc(2 + 1 + len * 2 + 1, GFP_KERNEL);
+ if (!req)
+ return ERR_PTR(-ENOMEM);
+
+ if (partial) {
+ *p++ = 'i';
+ *p++ = 'd';
+ } else {
+ *p++ = 'e';
+ *p++ = 'x';
+ }
+ *p++ = ':';
+ p = bin2hex(p, lookup, len);
+ *p = 0;
+
+ pr_debug("Look up: \"%s\"\n", req);
+
+ ref = keyring_search(make_key_ref(keyring, 1),
+ &key_type_asymmetric, req);
+ if (IS_ERR(ref))
+ pr_debug("Request for key '%s' err %ld\n", req, PTR_ERR(ref));
+ kfree(req);
+
+ if (IS_ERR(ref)) {
+ switch (PTR_ERR(ref)) {
+ /* Hide some search errors */
+ case -EACCES:
+ case -ENOTDIR:
+ case -EAGAIN:
+ return ERR_PTR(-ENOKEY);
+ default:
+ return ERR_CAST(ref);
+ }
+ }
+
+ key = key_ref_to_ptr(ref);
+ if (id && skid) {
+ const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
+ if (!kids->id[1]) {
+ pr_debug("issuer+serial match, but expected SKID missing\n");
+ goto reject;
+ }
+ if (!asymmetric_key_id_same(skid, kids->id[1])) {
+ pr_debug("issuer+serial match, but SKID does not\n");
+ goto reject;
+ }
+ }
+
+ pr_devel("<==%s() = 0 [%x]\n", __func__, key_serial(key));
+ return key;
+
+reject:
+ key_put(key);
+ return ERR_PTR(-EKEYREJECTED);
+}
+EXPORT_SYMBOL_GPL(x509_request_asymmetric_key);
+
+/*
+ * 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.
+ */
+int x509_validate_trust(struct x509_certificate *cert,
+ struct key *trust_keyring)
+{
+ struct public_key_signature *sig = cert->sig;
+ struct key *key;
+ int ret = 1;
+
+ if (!sig->auth_ids[0] && !sig->auth_ids[1])
+ return 1;
+
+ if (!trust_keyring)
+ return -EOPNOTSUPP;
+ if (ca_keyid && !asymmetric_key_id_partial(sig->auth_ids[1], ca_keyid))
+ return -EPERM;
+ if (cert->unsupported_sig)
+ return -ENOPKG;
+
+ key = x509_request_asymmetric_key(trust_keyring,
+ sig->auth_ids[0], sig->auth_ids[1],
+ false);
+ if (IS_ERR(key))
+ return PTR_ERR(key);
+
+ if (!use_builtin_keys ||
+ test_bit(KEY_FLAG_BUILTIN, &key->flags)) {
+ ret = public_key_verify_signature(
+ key->payload.data[asym_crypto], cert->sig);
+ if (ret == -ENOPKG)
+ cert->unsupported_sig = true;
+ }
+ key_put(key);
+ return ret;
+}
diff --git a/crypto/asymmetric_keys/x509_parser.h b/crypto/asymmetric_keys/x509_parser.h
index 05eef1c68881..7a802b09a509 100644
--- a/crypto/asymmetric_keys/x509_parser.h
+++ b/crypto/asymmetric_keys/x509_parser.h
@@ -58,3 +58,9 @@ extern int x509_decode_time(time64_t *_t, size_t hdrlen,
*/
extern int x509_get_sig_params(struct x509_certificate *cert);
extern int x509_check_for_self_signed(struct x509_certificate *cert);
+
+/*
+ * public_key_trust.c
+ */
+extern int x509_validate_trust(struct x509_certificate *cert,
+ struct key *trust_keyring);
diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
index 8ef99fac821f..c5c2fbc8c847 100644
--- a/crypto/asymmetric_keys/x509_public_key.c
+++ b/crypto/asymmetric_keys/x509_public_key.c
@@ -24,133 +24,6 @@
#include "public_key.h"
#include "x509_parser.h"
-static bool use_builtin_keys;
-static struct asymmetric_key_id *ca_keyid;
-
-#ifndef MODULE
-static struct {
- struct asymmetric_key_id id;
- unsigned char data[10];
-} cakey;
-
-static int __init ca_keys_setup(char *str)
-{
- if (!str) /* default system keyring */
- return 1;
-
- if (strncmp(str, "id:", 3) == 0) {
- struct asymmetric_key_id *p = &cakey.id;
- size_t hexlen = (strlen(str) - 3) / 2;
- int ret;
-
- if (hexlen == 0 || hexlen > sizeof(cakey.data)) {
- pr_err("Missing or invalid ca_keys id\n");
- return 1;
- }
-
- ret = __asymmetric_key_hex_to_key_id(str + 3, p, hexlen);
- if (ret < 0)
- pr_err("Unparsable ca_keys id hex string\n");
- else
- ca_keyid = p; /* owner key 'id:xxxxxx' */
- } else if (strcmp(str, "builtin") == 0) {
- use_builtin_keys = true;
- }
-
- return 1;
-}
-__setup("ca_keys=", ca_keys_setup);
-#endif
-
-/**
- * x509_request_asymmetric_key - Request a key by X.509 certificate params.
- * @keyring: The keys to search.
- * @id: The issuer & serialNumber to look for or NULL.
- * @skid: The subjectKeyIdentifier to look for or NULL.
- * @partial: Use partial match if true, exact if false.
- *
- * Find a key in the given keyring by identifier. The preferred identifier is
- * the issuer + serialNumber and the fallback identifier is the
- * subjectKeyIdentifier. If both are given, the lookup is by the former, but
- * the latter must also match.
- */
-struct key *x509_request_asymmetric_key(struct key *keyring,
- const struct asymmetric_key_id *id,
- const struct asymmetric_key_id *skid,
- bool partial)
-{
- struct key *key;
- key_ref_t ref;
- const char *lookup;
- char *req, *p;
- int len;
-
- if (id) {
- lookup = id->data;
- len = id->len;
- } else {
- lookup = skid->data;
- len = skid->len;
- }
-
- /* Construct an identifier "id:<keyid>". */
- p = req = kmalloc(2 + 1 + len * 2 + 1, GFP_KERNEL);
- if (!req)
- return ERR_PTR(-ENOMEM);
-
- if (partial) {
- *p++ = 'i';
- *p++ = 'd';
- } else {
- *p++ = 'e';
- *p++ = 'x';
- }
- *p++ = ':';
- p = bin2hex(p, lookup, len);
- *p = 0;
-
- pr_debug("Look up: \"%s\"\n", req);
-
- ref = keyring_search(make_key_ref(keyring, 1),
- &key_type_asymmetric, req);
- if (IS_ERR(ref))
- pr_debug("Request for key '%s' err %ld\n", req, PTR_ERR(ref));
- kfree(req);
-
- if (IS_ERR(ref)) {
- switch (PTR_ERR(ref)) {
- /* Hide some search errors */
- case -EACCES:
- case -ENOTDIR:
- case -EAGAIN:
- return ERR_PTR(-ENOKEY);
- default:
- return ERR_CAST(ref);
- }
- }
-
- key = key_ref_to_ptr(ref);
- if (id && skid) {
- const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
- if (!kids->id[1]) {
- pr_debug("issuer+serial match, but expected SKID missing\n");
- goto reject;
- }
- if (!asymmetric_key_id_same(skid, kids->id[1])) {
- pr_debug("issuer+serial match, but SKID does not\n");
- goto reject;
- }
- }
-
- pr_devel("<==%s() = 0 [%x]\n", __func__, key_serial(key));
- return key;
-
-reject:
- key_put(key);
- return ERR_PTR(-EKEYREJECTED);
-}
-EXPORT_SYMBOL_GPL(x509_request_asymmetric_key);
-
/*
* Set up the signature parameters in an X.509 certificate. This involves
* digesting the signed data and extracting the signature.
@@ -283,49 +156,6 @@ not_self_signed:
}
/*
- * 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)
-{
- struct public_key_signature *sig = cert->sig;
- struct key *key;
- int ret = 1;
-
- if (!sig->auth_ids[0] && !sig->auth_ids[1])
- return 1;
-
- if (!trust_keyring)
- return -EOPNOTSUPP;
- if (ca_keyid && !asymmetric_key_id_partial(sig->auth_ids[1], ca_keyid))
- return -EPERM;
- if (cert->unsupported_sig)
- return -ENOPKG;
-
- key = x509_request_asymmetric_key(trust_keyring,
- sig->auth_ids[0], sig->auth_ids[1],
- false);
- if (IS_ERR(key))
- return PTR_ERR(key);
-
- if (!use_builtin_keys ||
- test_bit(KEY_FLAG_BUILTIN, &key->flags)) {
- ret = public_key_verify_signature(
- key->payload.data[asym_crypto], cert->sig);
- if (ret == -ENOPKG)
- cert->unsupported_sig = true;
- }
- key_put(key);
- return ret;
-}
-
-/*
* Attempt to parse a data blob for a key as an X509 certificate.
*/
static int x509_key_preparse(struct key_preparsed_payload *prep)
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