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-rw-r--r--security/keys/keyring.c73
1 files changed, 66 insertions, 7 deletions
diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index f931ccfeefb0..d2d1f3378008 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -491,13 +491,18 @@ static long keyring_read(const struct key *keyring,
*/
struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
const struct cred *cred, key_perm_t perm,
- unsigned long flags, struct key *dest)
+ unsigned long flags,
+ int (*restrict_link)(struct key *,
+ const struct key_type *,
+ unsigned long,
+ const union key_payload *),
+ struct key *dest)
{
struct key *keyring;
int ret;
keyring = key_alloc(&key_type_keyring, description,
- uid, gid, cred, perm, flags);
+ uid, gid, cred, perm, flags, restrict_link);
if (!IS_ERR(keyring)) {
ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
if (ret < 0) {
@@ -510,6 +515,51 @@ struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
}
EXPORT_SYMBOL(keyring_alloc);
+/**
+ * keyring_restrict_trusted_only - Restrict additions to a keyring to trusted keys only
+ * @keyring: The keyring being added to.
+ * @type: The type of key being added.
+ * @flags: The key flags.
+ * @payload: The payload of the key intended to be added.
+ *
+ * Reject the addition of any links to a keyring that point to keys that aren't
+ * marked as being trusted. It can be overridden by passing
+ * KEY_ALLOC_BYPASS_RESTRICTION to key_instantiate_and_link() when adding a key
+ * to a keyring.
+ *
+ * This is meant to be passed as the restrict_link parameter to
+ * keyring_alloc().
+ */
+int keyring_restrict_trusted_only(struct key *keyring,
+ const struct key_type *type,
+ unsigned long flags,
+ const union key_payload *payload)
+{
+ return flags & KEY_FLAG_TRUSTED ? 0 : -EPERM;
+}
+
+/**
+ * restrict_link_reject - Give -EPERM to restrict link
+ * @keyring: The keyring being added to.
+ * @type: The type of key being added.
+ * @flags: The key flags.
+ * @payload: The payload of the key intended to be added.
+ *
+ * Reject the addition of any links to a keyring. It can be overridden by
+ * passing KEY_ALLOC_BYPASS_RESTRICTION to key_instantiate_and_link() when
+ * adding a key to a keyring.
+ *
+ * This is meant to be passed as the restrict_link parameter to
+ * keyring_alloc().
+ */
+int restrict_link_reject(struct key *keyring,
+ const struct key_type *type,
+ unsigned long flags,
+ const union key_payload *payload)
+{
+ return -EPERM;
+}
+
/*
* By default, we keys found by getting an exact match on their descriptions.
*/
@@ -1191,6 +1241,17 @@ void __key_link_end(struct key *keyring,
up_write(&keyring->sem);
}
+/*
+ * Check addition of keys to restricted keyrings.
+ */
+static int __key_link_check_restriction(struct key *keyring, struct key *key)
+{
+ if (!keyring->restrict_link)
+ return 0;
+ return keyring->restrict_link(keyring,
+ key->type, key->flags, &key->payload);
+}
+
/**
* key_link - Link a key to a keyring
* @keyring: The keyring to make the link in.
@@ -1221,14 +1282,12 @@ int key_link(struct key *keyring, struct key *key)
key_check(keyring);
key_check(key);
- if (test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags) &&
- !test_bit(KEY_FLAG_TRUSTED, &key->flags))
- return -EPERM;
-
ret = __key_link_begin(keyring, &key->index_key, &edit);
if (ret == 0) {
kdebug("begun {%d,%d}", keyring->serial, atomic_read(&keyring->usage));
- ret = __key_link_check_live_key(keyring, key);
+ ret = __key_link_check_restriction(keyring, key);
+ if (ret == 0)
+ ret = __key_link_check_live_key(keyring, key);
if (ret == 0)
__key_link(key, &edit);
__key_link_end(keyring, &key->index_key, edit);