CRED: Inaugurate COW credentials

[linux-block.git] / include / linux / cred.h

diff --git a/include/linux/cred.h b/include/linux/cred.h
index 62b9e532422d2214735f57708f01446525632ce6..eaf6fa695a0475fd324579f514cb7a02d90f1272 100644 (file)
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -84,6 +84,8 @@ struct thread_group_cred {
        struct key      *process_keyring;       /* keyring private to this process */
        struct rcu_head rcu;                    /* RCU deletion hook */
 };
+
+extern void release_tgcred(struct cred *cred);
 #endif
 
 /*
@@ -137,11 +139,30 @@ struct cred {
        struct user_struct *user;       /* real user ID subscription */
        struct group_info *group_info;  /* supplementary groups for euid/fsgid */
        struct rcu_head rcu;            /* RCU deletion hook */
-       spinlock_t      lock;           /* lock for pointer changes */
 };
 
 extern void __put_cred(struct cred *);
 extern int copy_creds(struct task_struct *, unsigned long);
+extern struct cred *prepare_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 void __init cred_init(void);
+
+/**
+ * get_new_cred - Get a reference on a new set of credentials
+ * @cred: The new credentials to reference
+ *
+ * Get a reference on the specified set of new credentials.  The caller must
+ * release the reference.
+ */
+static inline struct cred *get_new_cred(struct cred *cred)
+{
+       atomic_inc(&cred->usage);
+       return cred;
+}
 
 /**
  * get_cred - Get a reference on a set of credentials
@@ -150,10 +171,9 @@ extern int copy_creds(struct task_struct *, unsigned long);
  * Get a reference on the specified set of credentials.  The caller must
  * release the reference.
  */
-static inline struct cred *get_cred(struct cred *cred)
+static inline const struct cred *get_cred(const struct cred *cred)
 {
-       atomic_inc(&cred->usage);
-       return cred;
+       return get_new_cred((struct cred *) cred);
 }
 
 /**
@@ -166,6 +186,8 @@ static inline struct cred *get_cred(struct cred *cred)
 static inline void put_cred(const struct cred *_cred)
 {
        struct cred *cred = (struct cred *) _cred;
+
+       BUG_ON(atomic_read(&(cred)->usage) <= 0);
        if (atomic_dec_and_test(&(cred)->usage))
                __put_cred(cred);
 }
@@ -250,13 +272,13 @@ static inline void put_cred(const struct cred *_cred)
        __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_cred_xxx(task, xxx)                       \
+({                                                     \
+       __typeof__(((struct cred *)NULL)->xxx) ___val;  \
+       rcu_read_lock();                                \
+       ___val = __task_cred((task))->xxx;              \
+       rcu_read_unlock();                              \
+       ___val;                                         \
 })
 
 #define task_uid(task)         (task_cred_xxx((task), uid))