CRED: Separate per-task-group keyrings from signal_struct

Separate per-task-group keyrings from signal_struct and dangle their anchor
from the cred struct rather than the signal_struct.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: James Morris <jmorris@namei.org>
Signed-off-by: James Morris <jmorris@namei.org>

3 files changed, 18 insertions, 12 deletions

diff --git a/include/linux/cred.h b/include/linux/cred.h
index 166ce4ddba64..62b9e532422d 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -72,6 +72,21 @@ extern int in_group_p(gid_t);
 extern int in_egroup_p(gid_t);
 
 /*
+ * The common credentials for a thread group
+ * - shared by CLONE_THREAD
+ */
+#ifdef CONFIG_KEYS
+struct thread_group_cred {
+        atomic_t        usage;
+        pid_t           tgid;                   /* thread group process ID */
+        spinlock_t      lock;
+        struct key      *session_keyring;       /* keyring inherited over fork */
+        struct key      *process_keyring;       /* keyring private to this process */
+        struct rcu_head rcu;                    /* RCU deletion hook */
+};
+#endif
+
+/*
  * The security context of a task
  *
  * The parts of the context break down into two categories:
@@ -114,6 +129,7 @@ struct cred {
                                          * keys to */
         struct key      *thread_keyring; /* keyring private to this thread */
         struct key      *request_key_auth; /* assumed request_key authority */
+        struct thread_group_cred *tgcred; /* thread-group shared credentials */
 #endif
 #ifdef CONFIG_SECURITY
         void            *security;      /* subjective LSM security */
diff --git a/include/linux/key.h b/include/linux/key.h
index df709e1af3cd..0836cc838b0c 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -278,9 +278,7 @@ extern ctl_table key_sysctls[];
  */
 extern void switch_uid_keyring(struct user_struct *new_user);
 extern int copy_keys(unsigned long clone_flags, struct task_struct *tsk);
-extern int copy_thread_group_keys(struct task_struct *tsk);
 extern void exit_keys(struct task_struct *tsk);
-extern void exit_thread_group_keys(struct signal_struct *tg);
 extern int suid_keys(struct task_struct *tsk);
 extern int exec_keys(struct task_struct *tsk);
 extern void key_fsuid_changed(struct task_struct *tsk);
@@ -289,8 +287,8 @@ extern void key_init(void);
 
 #define __install_session_keyring(keyring)                              \
 ({                                                                      \
-        struct key *old_session = current->signal->session_keyring;     \
-        current->signal->session_keyring = keyring;                     \
+        struct key *old_session = current->cred->tgcred->session_keyring; \
+        current->cred->tgcred->session_keyring = keyring;               \
         old_session;                                                    \
 })
 
@@ -308,9 +306,7 @@ extern void key_init(void);
 #define switch_uid_keyring(u)           do { } while(0)
 #define __install_session_keyring(k)    ({ NULL; })
 #define copy_keys(f,t)                  0
-#define copy_thread_group_keys(t)       0
 #define exit_keys(t)                    do { } while(0)
-#define exit_thread_group_keys(tg)      do { } while(0)
 #define suid_keys(t)                    do { } while(0)
 #define exec_keys(t)                    do { } while(0)
 #define key_fsuid_changed(t)            do { } while(0)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 740cf946c8cc..2913252989b3 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -571,12 +571,6 @@ struct signal_struct {
          */
         struct rlimit rlim[RLIM_NLIMITS];
 
-        /* keep the process-shared keyrings here so that they do the right
-         * thing in threads created with CLONE_THREAD */
-#ifdef CONFIG_KEYS
-        struct key *session_keyring;    /* keyring inherited over fork */
-        struct key *process_keyring;    /* keyring private to this process */
-#endif
 #ifdef CONFIG_BSD_PROCESS_ACCT
         struct pacct_struct pacct;      /* per-process accounting information */
 #endif