keys: Namespace keyring names
Keyring names are held in a single global list that any process can pick
from by means of keyctl_join_session_keyring (provided the keyring grants
Search permission). This isn't very container friendly, however.
Make the following changes:
(1) Make default session, process and thread keyring names begin with a
'.' instead of '_'.
(2) Keyrings whose names begin with a '.' aren't added to the list. Such
keyrings are system specials.
(3) Replace the global list with per-user_namespace lists. A keyring adds
its name to the list for the user_namespace that it is currently in.
(4) When a user_namespace is deleted, it just removes itself from the
keyring name list.
The global keyring_name_lock is retained for accessing the name lists.
This allows (4) to work.
This can be tested by:
# keyctl newring foo @s
995906392
# unshare -U
$ keyctl show
...
995906392 --alswrv 65534 65534 \_ keyring: foo
...
$ keyctl session foo
Joined session keyring: 935622349
As can be seen, a new session keyring was created.
The capability bit KEYCTL_CAPS1_NS_KEYRING_NAME is set if the kernel is
employing this feature.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Eric W. Biederman <ebiederm@xmission.com>
diff --git a/include/linux/key.h b/include/linux/key.h
index ff10273..ae11773 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -361,6 +361,7 @@ extern void key_set_timeout(struct key *, unsigned);
extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
key_perm_t perm);
+extern void key_free_user_ns(struct user_namespace *);
/*
* The permissions required on a key that we're looking up.
@@ -434,6 +435,7 @@ extern void key_init(void);
#define key_fsuid_changed(c) do { } while(0)
#define key_fsgid_changed(c) do { } while(0)
#define key_init() do { } while(0)
+#define key_free_user_ns(ns) do { } while(0)
#endif /* CONFIG_KEYS */
#endif /* __KERNEL__ */
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index d6b74b9..9045701 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -64,6 +64,11 @@ struct user_namespace {
struct ns_common ns;
unsigned long flags;
+#ifdef CONFIG_KEYS
+ /* List of joinable keyrings in this namespace */
+ struct list_head keyring_name_list;
+#endif
+
/* Register of per-UID persistent keyrings for this namespace */
#ifdef CONFIG_PERSISTENT_KEYRINGS
struct key *persistent_keyring_register;