Merge remote-tracking branch 'integrity/next-with-keys' into keys-next

Signed-off-by: David Howells <dhowells@redhat.com>

3 files changed, 142 insertions, 20 deletions

diff --git a/crypto/asymmetric_keys/asymmetric_keys.h b/crypto/asymmetric_keys/asymmetric_keys.h
index 515b63430812..a63c551c6557 100644
--- a/crypto/asymmetric_keys/asymmetric_keys.h
+++ b/crypto/asymmetric_keys/asymmetric_keys.h
@@ -9,6 +9,8 @@
  * 2 of the Licence, or (at your option) any later version.
  */
 
+int asymmetric_keyid_match(const char *kid, const char *id);
+
 static inline const char *asymmetric_key_id(const struct key *key)
 {
         return key->type_data.p[1];
diff --git a/crypto/asymmetric_keys/asymmetric_type.c b/crypto/asymmetric_keys/asymmetric_type.c
index 21960a4e74e8..eb8cd46961a5 100644
--- a/crypto/asymmetric_keys/asymmetric_type.c
+++ b/crypto/asymmetric_keys/asymmetric_type.c
@@ -23,6 +23,35 @@ static LIST_HEAD(asymmetric_key_parsers);
 static DECLARE_RWSEM(asymmetric_key_parsers_sem);
 
 /*
+ * Match asymmetric key id with partial match
+ * @id:         key id to match in a form "id:<id>"
+ */
+int asymmetric_keyid_match(const char *kid, const char *id)
+{
+        size_t idlen, kidlen;
+
+        if (!kid || !id)
+                return 0;
+
+        /* make it possible to use id as in the request: "id:<id>" */
+        if (strncmp(id, "id:", 3) == 0)
+                id += 3;
+
+        /* Anything after here requires a partial match on the ID string */
+        idlen = strlen(id);
+        kidlen = strlen(kid);
+        if (idlen > kidlen)
+                return 0;
+
+        kid += kidlen - idlen;
+        if (strcasecmp(id, kid) != 0)
+                return 0;
+
+        return 1;
+}
+EXPORT_SYMBOL_GPL(asymmetric_keyid_match);
+
+/*
  * Match asymmetric keys on (part of) their name
  * We have some shorthand methods for matching keys.  We allow:
  *
@@ -34,9 +63,8 @@ static int asymmetric_key_match(const struct key *key, const void *description)
 {
         const struct asymmetric_key_subtype *subtype = asymmetric_key_subtype(key);
         const char *spec = description;
-        const char *id, *kid;
+        const char *id;
         ptrdiff_t speclen;
-        size_t idlen, kidlen;
 
         if (!subtype || !spec || !*spec)
                 return 0;
@@ -55,23 +83,8 @@ static int asymmetric_key_match(const struct key *key, const void *description)
         speclen = id - spec;
         id++;
 
-        /* Anything after here requires a partial match on the ID string */
-        kid = asymmetric_key_id(key);
-        if (!kid)
-                return 0;
-
-        idlen = strlen(id);
-        kidlen = strlen(kid);
-        if (idlen > kidlen)
-                return 0;
-
-        kid += kidlen - idlen;
-        if (strcasecmp(id, kid) != 0)
-                return 0;
-
-        if (speclen == 2 &&
-            memcmp(spec, "id", 2) == 0)
-                return 1;
+        if (speclen == 2 && memcmp(spec, "id", 2) == 0)
+                return asymmetric_keyid_match(asymmetric_key_id(key), id);
 
         if (speclen == subtype->name_len &&
             memcmp(spec, subtype->name, speclen) == 0)
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 */