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,