From 0f44e4d976f96c6439da0d6717238efa4b91196e Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 26 Jun 2019 21:02:32 +0100 Subject: keys: Move the user and user-session keyrings to the user_namespace Move the user and user-session keyrings to the user_namespace struct rather than pinning them from the user_struct struct. This prevents these keyrings from propagating across user-namespaces boundaries with regard to the KEY_SPEC_* flags, thereby making them more useful in a containerised environment. The issue is that a single user_struct may be represent UIDs in several different namespaces. The way the patch does this is by attaching a 'register keyring' in each user_namespace and then sticking the user and user-session keyrings into that. It can then be searched to retrieve them. Signed-off-by: David Howells cc: Jann Horn --- include/linux/sched/user.h | 14 -------------- include/linux/user_namespace.h | 9 +++++++-- 2 files changed, 7 insertions(+), 16 deletions(-) (limited to 'include') diff --git a/include/linux/sched/user.h b/include/linux/sched/user.h index 468d2565a9fe..917d88edb7b9 100644 --- a/include/linux/sched/user.h +++ b/include/linux/sched/user.h @@ -7,8 +7,6 @@ #include #include -struct key; - /* * Some day this will be a full-fledged user tracking system.. */ @@ -30,18 +28,6 @@ struct user_struct { unsigned long unix_inflight; /* How many files in flight in unix sockets */ atomic_long_t pipe_bufs; /* how many pages are allocated in pipe buffers */ -#ifdef CONFIG_KEYS - /* - * These pointers can only change from NULL to a non-NULL value once. - * Writes are protected by key_user_keyring_mutex. - * Unlocked readers should use READ_ONCE() unless they know that - * install_user_keyrings() has been called successfully (which sets - * these members to non-NULL values, preventing further modifications). - */ - struct key *uid_keyring; /* UID specific keyring */ - struct key *session_keyring; /* UID's default session keyring */ -#endif - /* Hash table maintenance information */ struct hlist_node uidhash_node; kuid_t uid; diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h index 90457015fa3f..fb9f4f799554 100644 --- a/include/linux/user_namespace.h +++ b/include/linux/user_namespace.h @@ -65,14 +65,19 @@ struct user_namespace { unsigned long flags; #ifdef CONFIG_KEYS - /* List of joinable keyrings in this namespace */ + /* List of joinable keyrings in this namespace. Modification access of + * these pointers is controlled by keyring_sem. Once + * user_keyring_register is set, it won't be changed, so it can be + * accessed directly with READ_ONCE(). + */ struct list_head keyring_name_list; + struct key *user_keyring_register; + struct rw_semaphore keyring_sem; #endif /* Register of per-UID persistent keyrings for this namespace */ #ifdef CONFIG_PERSISTENT_KEYRINGS struct key *persistent_keyring_register; - struct rw_semaphore persistent_keyring_register_sem; #endif struct work_struct work; #ifdef CONFIG_SYSCTL -- cgit v1.2.3