CRED: Detach the credentials from task_struct

Detach the credentials from task_struct, duplicating them in copy_process()
and releasing them in __put_task_struct().

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>

4 files changed, 43 insertions, 29 deletions

diff --git a/include/linux/cred.h b/include/linux/cred.h
index 3e65587a72e5..a7a686074cb0 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -158,4 +158,33 @@ do {						\
         *(_gid) = current->cred->fsgid;         \
 } while(0)
 
+extern void __put_cred(struct cred *);
+extern int copy_creds(struct task_struct *, unsigned long);
+
+/**
+ * get_cred - Get a reference on a set of credentials
+ * @cred: The credentials to reference
+ *
+ * Get a reference on the specified set of credentials.  The caller must
+ * release the reference.
+ */
+static inline struct cred *get_cred(struct cred *cred)
+{
+        atomic_inc(&cred->usage);
+        return cred;
+}
+
+/**
+ * put_cred - Release a reference to a set of credentials
+ * @cred: The credentials to release
+ *
+ * Release a reference to a set of credentials, deleting them when the last ref
+ * is released.
+ */
+static inline void put_cred(struct cred *cred)
+{
+        if (atomic_dec_and_test(&(cred)->usage))
+                __put_cred(cred);
+}
+
 #endif /* _LINUX_CRED_H */
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 9de41ccd67b5..5e24c54b6dfd 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -115,19 +115,6 @@ extern struct group_info init_groups;
 
 extern struct cred init_cred;
 
-#define INIT_CRED(p)                                            \
-{                                                               \
-        .usage                  = ATOMIC_INIT(3),               \
-        .securebits             = SECUREBITS_DEFAULT,           \
-        .cap_inheritable        = CAP_INIT_INH_SET,             \
-        .cap_permitted          = CAP_FULL_SET,                 \
-        .cap_effective          = CAP_INIT_EFF_SET,             \
-        .cap_bset               = CAP_INIT_BSET,                \
-        .user                   = INIT_USER,                    \
-        .group_info             = &init_groups,                 \
-        .lock                   = __SPIN_LOCK_UNLOCKED(p.lock), \
-}
-
 /*
  *  INIT_TASK is used to set up the first task table, touch at
  * your own risk!. Base=0, limit=0x1fffff (=2MB)
@@ -162,8 +149,7 @@ extern struct cred init_cred;
         .children       = LIST_HEAD_INIT(tsk.children),                 \
         .sibling        = LIST_HEAD_INIT(tsk.sibling),                  \
         .group_leader   = &tsk,                                         \
-        .__temp_cred    = INIT_CRED(tsk.__temp_cred),                   \
-        .cred           = &tsk.__temp_cred,                             \
+        .cred           = &init_cred,                                   \
         .comm           = "swapper",                                    \
         .thread         = INIT_THREAD,                                  \
         .fs             = &init_fs,                                     \
diff --git a/include/linux/sched.h b/include/linux/sched.h
index c8b92502354d..740cf946c8cc 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1151,7 +1151,6 @@ struct task_struct {
         struct list_head cpu_timers[3];
 
 /* process credentials */
-        struct cred __temp_cred __deprecated; /* temporary credentials to be removed */
         struct cred *cred;      /* actual/objective task credentials */
 
         char comm[TASK_COMM_LEN]; /* executable name excluding path
diff --git a/include/linux/security.h b/include/linux/security.h
index 9f305d4a31a7..9239cc11eb9c 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -593,15 +593,15 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
  *      manual page for definitions of the @clone_flags.
  *      @clone_flags contains the flags indicating what should be shared.
  *      Return 0 if permission is granted.
- * @task_alloc_security:
- *      @p contains the task_struct for child process.
- *      Allocate and attach a security structure to the p->security field. The
- *      security field is initialized to NULL when the task structure is
+ * @cred_alloc_security:
+ *      @cred contains the cred struct for child process.
+ *      Allocate and attach a security structure to the cred->security field.
+ *      The security field is initialized to NULL when the task structure is
  *      allocated.
  *      Return 0 if operation was successful.
- * @task_free_security:
- *      @p contains the task_struct for process.
- *      Deallocate and clear the p->security field.
+ * @cred_free:
+ *      @cred points to the credentials.
+ *      Deallocate and clear the cred->security field in a set of credentials.
  * @task_setuid:
  *      Check permission before setting one or more of the user identity
  *      attributes of the current process.  The @flags parameter indicates
@@ -1405,8 +1405,8 @@ struct security_operations {
         int (*dentry_open) (struct file *file);
 
         int (*task_create) (unsigned long clone_flags);
-        int (*task_alloc_security) (struct task_struct *p);
-        void (*task_free_security) (struct task_struct *p);
+        int (*cred_alloc_security) (struct cred *cred);
+        void (*cred_free) (struct cred *cred);
         int (*task_setuid) (uid_t id0, uid_t id1, uid_t id2, int flags);
         int (*task_post_setuid) (uid_t old_ruid /* or fsuid */ ,
                                  uid_t old_euid, uid_t old_suid, int flags);
@@ -1660,8 +1660,8 @@ int security_file_send_sigiotask(struct task_struct *tsk,
 int security_file_receive(struct file *file);
 int security_dentry_open(struct file *file);
 int security_task_create(unsigned long clone_flags);
-int security_task_alloc(struct task_struct *p);
-void security_task_free(struct task_struct *p);
+int security_cred_alloc(struct cred *cred);
+void security_cred_free(struct cred *cred);
 int security_task_setuid(uid_t id0, uid_t id1, uid_t id2, int flags);
 int security_task_post_setuid(uid_t old_ruid, uid_t old_euid,
                               uid_t old_suid, int flags);
@@ -2181,12 +2181,12 @@ static inline int security_task_create(unsigned long clone_flags)
         return 0;
 }
 
-static inline int security_task_alloc(struct task_struct *p)
+static inline int security_cred_alloc(struct cred *cred)
 {
         return 0;
 }
 
-static inline void security_task_free(struct task_struct *p)
+static inline void security_cred_free(struct cred *cred)
 { }
 
 static inline int security_task_setuid(uid_t id0, uid_t id1, uid_t id2,