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path: root/crypto/asymmetric_keys/x509_public_key.c
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Diffstat (limited to 'crypto/asymmetric_keys/x509_public_key.c')
-rw-r--r--crypto/asymmetric_keys/x509_public_key.c109
1 files changed, 108 insertions, 1 deletions
diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
index 3fc8a0634ed7..a0f7cd196c9b 100644
--- a/crypto/asymmetric_keys/x509_public_key.c
+++ b/crypto/asymmetric_keys/x509_public_key.c
@@ -18,11 +18,80 @@
#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 char *ca_keyid;
+
+#ifndef MODULE
+static int __init ca_keys_setup(char *str)
+{
+ if (!str) /* default system keyring */
+ return 1;
+
+ if (strncmp(str, "id:", 3) == 0)
+ ca_keyid = str; /* owner key 'id:xxxxxx' */
+ else if (strcmp(str, "builtin") == 0)
+ use_builtin_keys = true;
+
+ return 1;
+}
+__setup("ca_keys=", ca_keys_setup);
+#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);
+}
+
/*
* Set up the signature parameters in an X.509 certificate. This involves
* digesting the signed data and extracting the signature.
@@ -103,6 +172,40 @@ int x509_check_signature(const struct public_key *pub,
EXPORT_SYMBOL_GPL(x509_check_signature);
/*
+ * 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 key *key;
+ int ret = 1;
+
+ if (!trust_keyring)
+ return -EOPNOTSUPP;
+
+ if (ca_keyid && !asymmetric_keyid_match(cert->authority, ca_keyid))
+ return -EPERM;
+
+ key = x509_request_asymmetric_key(trust_keyring,
+ cert->issuer, strlen(cert->issuer),
+ cert->authority,
+ strlen(cert->authority));
+ if (!IS_ERR(key)) {
+ if (!use_builtin_keys
+ || test_bit(KEY_FLAG_BUILTIN, &key->flags))
+ ret = x509_check_signature(key->payload.data, cert);
+ 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)
@@ -155,9 +258,13 @@ static int x509_key_preparse(struct key_preparsed_payload *prep)
/* 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);
+ ret = x509_check_signature(cert->pub, cert); /* self-signed */
if (ret < 0)
goto error_free_cert;
+ } else if (!prep->trusted) {
+ ret = x509_validate_trust(cert, get_system_trusted_keyring());
+ if (!ret)
+ prep->trusted = 1;
}
/* Propose a description */