Merge branch 'keys-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

Pull key handling fixes from David Howells:
 "Here are two patches, the first of which at least should go upstream
  immediately:

  (1) Prevent a user-triggerable crash in the keyrings destructor when a
      negatively instantiated keyring is garbage collected.  I have also
      seen this triggered for user type keys.

  (2) Prevent the user from using requesting that a keyring be created
      and instantiated through an upcall.  Doing so is probably safe
      since the keyring type ignores the arguments to its instantiation
      function - but we probably shouldn't let keyrings be created in
      this manner"

* 'keys-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  KEYS: Don't permit request_key() to construct a new keyring
  KEYS: Fix crash when attempt to garbage collect an uninstantiated keyring

2 files changed, 7 insertions, 2 deletions

diff --git a/security/keys/gc.c b/security/keys/gc.c
index 39eac1fd5706..addf060399e0 100644
--- a/security/keys/gc.c
+++ b/security/keys/gc.c
@@ -134,8 +134,10 @@ static noinline void key_gc_unused_keys(struct list_head *keys)
                 kdebug("- %u", key->serial);
                 key_check(key);
 
-                /* Throw away the key data */
-                if (key->type->destroy)
+                /* Throw away the key data if the key is instantiated */
+                if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
+                    !test_bit(KEY_FLAG_NEGATIVE, &key->flags) &&
+                    key->type->destroy)
                         key->type->destroy(key);
 
                 security_key_free(key);
diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index 486ef6fa393b..0d6253124278 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -440,6 +440,9 @@ static struct key *construct_key_and_link(struct keyring_search_context *ctx,
 
         kenter("");
 
+        if (ctx->index_key.type == &key_type_keyring)
+                return ERR_PTR(-EPERM);
+        
         user = key_user_lookup(current_fsuid());
         if (!user)
                 return ERR_PTR(-ENOMEM);