CRED: Wrap current->cred and a few other accessors
Wrap current->cred and a few other accessors to hide their actual
implementation.
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>
diff --git a/include/linux/cred.h b/include/linux/cred.h
index a7a6860..4221ec6 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -37,15 +37,16 @@
* get_group_info - Get a reference to a group info structure
* @group_info: The group info to reference
*
- * This must be called with the owning task locked (via task_lock()) when task
- * != current. The reason being that the vast majority of callers are looking
- * at current->group_info, which can not be changed except by the current task.
- * Changing current->group_info requires the task lock, too.
+ * This gets a reference to a set of supplementary groups.
+ *
+ * If the caller is accessing a task's credentials, they must hold the RCU read
+ * lock when reading.
*/
-#define get_group_info(group_info) \
-do { \
- atomic_inc(&(group_info)->usage); \
-} while (0)
+static inline struct group_info *get_group_info(struct group_info *gi)
+{
+ atomic_inc(&gi->usage);
+ return gi;
+}
/**
* put_group_info - Release a reference to a group info structure
@@ -61,7 +62,7 @@
extern void groups_free(struct group_info *);
extern int set_current_groups(struct group_info *);
extern int set_groups(struct cred *, struct group_info *);
-extern int groups_search(struct group_info *, gid_t);
+extern int groups_search(const struct group_info *, gid_t);
/* access the groups "array" with this macro */
#define GROUP_AT(gi, i) \
@@ -123,41 +124,6 @@
spinlock_t lock; /* lock for pointer changes */
};
-#define get_current_user() (get_uid(current->cred->user))
-
-#define task_uid(task) ((task)->cred->uid)
-#define task_gid(task) ((task)->cred->gid)
-#define task_euid(task) ((task)->cred->euid)
-#define task_egid(task) ((task)->cred->egid)
-
-#define current_uid() (current->cred->uid)
-#define current_gid() (current->cred->gid)
-#define current_euid() (current->cred->euid)
-#define current_egid() (current->cred->egid)
-#define current_suid() (current->cred->suid)
-#define current_sgid() (current->cred->sgid)
-#define current_fsuid() (current->cred->fsuid)
-#define current_fsgid() (current->cred->fsgid)
-#define current_cap() (current->cred->cap_effective)
-
-#define current_uid_gid(_uid, _gid) \
-do { \
- *(_uid) = current->cred->uid; \
- *(_gid) = current->cred->gid; \
-} while(0)
-
-#define current_euid_egid(_uid, _gid) \
-do { \
- *(_uid) = current->cred->euid; \
- *(_gid) = current->cred->egid; \
-} while(0)
-
-#define current_fsuid_fsgid(_uid, _gid) \
-do { \
- *(_uid) = current->cred->fsuid; \
- *(_gid) = current->cred->fsgid; \
-} while(0)
-
extern void __put_cred(struct cred *);
extern int copy_creds(struct task_struct *, unsigned long);
@@ -187,4 +153,137 @@
__put_cred(cred);
}
+/**
+ * current_cred - Access the current task's credentials
+ *
+ * Access the credentials of the current task.
+ */
+#define current_cred() \
+ (current->cred)
+
+/**
+ * __task_cred - Access another task's credentials
+ * @task: The task to query
+ *
+ * Access the credentials of another task. The caller must hold the
+ * RCU readlock.
+ *
+ * The caller must make sure task doesn't go away, either by holding a ref on
+ * task or by holding tasklist_lock to prevent it from being unlinked.
+ */
+#define __task_cred(task) \
+ ((const struct cred *)(rcu_dereference((task)->cred)))
+
+/**
+ * get_task_cred - Get another task's credentials
+ * @task: The task to query
+ *
+ * Get the credentials of a task, pinning them so that they can't go away.
+ * Accessing a task's credentials directly is not permitted.
+ *
+ * The caller must make sure task doesn't go away, either by holding a ref on
+ * task or by holding tasklist_lock to prevent it from being unlinked.
+ */
+#define get_task_cred(task) \
+({ \
+ struct cred *__cred; \
+ rcu_read_lock(); \
+ __cred = (struct cred *) __task_cred((task)); \
+ get_cred(__cred); \
+ rcu_read_unlock(); \
+ __cred; \
+})
+
+/**
+ * get_current_cred - Get the current task's credentials
+ *
+ * Get the credentials of the current task, pinning them so that they can't go
+ * away. Accessing the current task's credentials directly is not permitted.
+ */
+#define get_current_cred() \
+ (get_cred(current_cred()))
+
+/**
+ * get_current_user - Get the current task's user_struct
+ *
+ * Get the user record of the current task, pinning it so that it can't go
+ * away.
+ */
+#define get_current_user() \
+({ \
+ struct user_struct *__u; \
+ struct cred *__cred; \
+ __cred = (struct cred *) current_cred(); \
+ __u = get_uid(__cred->user); \
+ __u; \
+})
+
+/**
+ * get_current_groups - Get the current task's supplementary group list
+ *
+ * Get the supplementary group list of the current task, pinning it so that it
+ * can't go away.
+ */
+#define get_current_groups() \
+({ \
+ struct group_info *__groups; \
+ struct cred *__cred; \
+ __cred = (struct cred *) current_cred(); \
+ __groups = get_group_info(__cred->group_info); \
+ __groups; \
+})
+
+#define task_cred_xxx(task, xxx) \
+({ \
+ __typeof__(task->cred->xxx) ___val; \
+ rcu_read_lock(); \
+ ___val = __task_cred((task))->xxx; \
+ rcu_read_unlock(); \
+ ___val; \
+})
+
+#define task_uid(task) (task_cred_xxx((task), uid))
+#define task_euid(task) (task_cred_xxx((task), euid))
+
+#define current_cred_xxx(xxx) \
+({ \
+ current->cred->xxx; \
+})
+
+#define current_uid() (current_cred_xxx(uid))
+#define current_gid() (current_cred_xxx(gid))
+#define current_euid() (current_cred_xxx(euid))
+#define current_egid() (current_cred_xxx(egid))
+#define current_suid() (current_cred_xxx(suid))
+#define current_sgid() (current_cred_xxx(sgid))
+#define current_fsuid() (current_cred_xxx(fsuid))
+#define current_fsgid() (current_cred_xxx(fsgid))
+#define current_cap() (current_cred_xxx(cap_effective))
+#define current_user() (current_cred_xxx(user))
+#define current_security() (current_cred_xxx(security))
+
+#define current_uid_gid(_uid, _gid) \
+do { \
+ const struct cred *__cred; \
+ __cred = current_cred(); \
+ *(_uid) = __cred->uid; \
+ *(_gid) = __cred->gid; \
+} while(0)
+
+#define current_euid_egid(_euid, _egid) \
+do { \
+ const struct cred *__cred; \
+ __cred = current_cred(); \
+ *(_euid) = __cred->euid; \
+ *(_egid) = __cred->egid; \
+} while(0)
+
+#define current_fsuid_fsgid(_fsuid, _fsgid) \
+do { \
+ const struct cred *__cred; \
+ __cred = current_cred(); \
+ *(_fsuid) = __cred->fsuid; \
+ *(_fsgid) = __cred->fsgid; \
+} while(0)
+
#endif /* _LINUX_CRED_H */
