From b206f281d0ee14969878469816a69db22d5838e8 Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 26 Jun 2019 21:02:32 +0100 Subject: 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 cc: Eric W. Biederman --- kernel/user.c | 3 +++ kernel/user_namespace.c | 7 ++++--- 2 files changed, 7 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/kernel/user.c b/kernel/user.c index 88b834f0eebc..50979fd1b7aa 100644 --- a/kernel/user.c +++ b/kernel/user.c @@ -62,6 +62,9 @@ struct user_namespace init_user_ns = { .ns.ops = &userns_operations, #endif .flags = USERNS_INIT_FLAGS, +#ifdef CONFIG_KEYS + .keyring_name_list = LIST_HEAD_INIT(init_user_ns.keyring_name_list), +#endif #ifdef CONFIG_PERSISTENT_KEYRINGS .persistent_keyring_register_sem = __RWSEM_INITIALIZER(init_user_ns.persistent_keyring_register_sem), diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index 923414a246e9..bda6e890ad88 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -133,6 +133,9 @@ int create_user_ns(struct cred *new) ns->flags = parent_ns->flags; mutex_unlock(&userns_state_mutex); +#ifdef CONFIG_KEYS + INIT_LIST_HEAD(&ns->keyring_name_list); +#endif #ifdef CONFIG_PERSISTENT_KEYRINGS init_rwsem(&ns->persistent_keyring_register_sem); #endif @@ -196,9 +199,7 @@ static void free_user_ns(struct work_struct *work) kfree(ns->projid_map.reverse); } retire_userns_sysctls(ns); -#ifdef CONFIG_PERSISTENT_KEYRINGS - key_put(ns->persistent_keyring_register); -#endif + key_free_user_ns(ns); ns_free_inum(&ns->ns); kmem_cache_free(user_ns_cachep, ns); dec_user_namespaces(ucounts); -- cgit v1.2.3-58-ga151