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authorDavid Howells <dhowells@redhat.com>2008-11-14 10:39:26 +1100
committerJames Morris <jmorris@namei.org>2008-11-14 10:39:26 +1100
commit3b11a1decef07c19443d24ae926982bc8ec9f4c0 (patch)
treeb6555f0e5b07f4b2badd332a0a900b974920c49d /include/linux/cred.h
parent98870ab0a5a3f1822aee681d2997017e1c87d026 (diff)
downloadlinux-3b11a1decef07c19443d24ae926982bc8ec9f4c0.tar.gz
CRED: Differentiate objective and effective subjective credentials on a task
Differentiate the objective and real subjective credentials from the effective subjective credentials on a task by introducing a second credentials pointer into the task_struct. task_struct::real_cred then refers to the objective and apparent real subjective credentials of a task, as perceived by the other tasks in the system. task_struct::cred then refers to the effective subjective credentials of a task, as used by that task when it's actually running. These are not visible to the other tasks in the system. __task_cred(task) then refers to the objective/real credentials of the task in question. current_cred() refers to the effective subjective credentials of the current task. prepare_creds() uses the objective creds as a base and commit_creds() changes both pointers in the task_struct (indeed commit_creds() requires them to be the same). override_creds() and revert_creds() change the subjective creds pointer only, and the former returns the old subjective creds. These are used by NFSD, faccessat() and do_coredump(), and will by used by CacheFiles. In SELinux, current_has_perm() is provided as an alternative to task_has_perm(). This uses the effective subjective context of current, whereas task_has_perm() uses the objective/real context of the subject. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'include/linux/cred.h')
-rw-r--r--include/linux/cred.h29
1 files changed, 15 insertions, 14 deletions
diff --git a/include/linux/cred.h b/include/linux/cred.h
index 794aab5c66e..55a9c995d69 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -146,8 +146,8 @@ extern struct cred *prepare_exec_creds(void);
extern struct cred *prepare_usermodehelper_creds(void);
extern int commit_creds(struct cred *);
extern void abort_creds(struct cred *);
-extern const struct cred *override_creds(const struct cred *) __deprecated;
-extern void revert_creds(const struct cred *) __deprecated;
+extern const struct cred *override_creds(const struct cred *);
+extern void revert_creds(const struct cred *);
extern void __init cred_init(void);
/**
@@ -202,32 +202,32 @@ static inline void put_cred(const struct cred *_cred)
}
/**
- * current_cred - Access the current task's credentials
+ * current_cred - Access the current task's subjective credentials
*
- * Access the credentials of the current task.
+ * Access the subjective credentials of the current task.
*/
#define current_cred() \
(current->cred)
/**
- * __task_cred - Access another task's credentials
+ * __task_cred - Access a task's objective credentials
* @task: The task to query
*
- * Access the credentials of another task. The caller must hold the
- * RCU readlock.
+ * Access the objective credentials of a 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)))
+ ((const struct cred *)(rcu_dereference((task)->real_cred)))
/**
- * get_task_cred - Get another task's credentials
+ * get_task_cred - Get another task's objective 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.
+ * Get the objective 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.
@@ -243,10 +243,11 @@ static inline void put_cred(const struct cred *_cred)
})
/**
- * get_current_cred - Get the current task's credentials
+ * get_current_cred - Get the current task's subjective 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.
+ * Get the subjective 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()))