1 files changed, 29 insertions, 40 deletions

diff --git a/include/linux/cred.h b/include/linux/cred.h
index e4a3155fe409..343a140a6ba2 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -20,6 +20,8 @@
 struct cred;
 struct inode;
 
+extern struct task_struct init_task;
+
 /*
  * COW Supplementary groups list
  */
@@ -148,16 +150,19 @@ struct cred {
 
 extern void __put_cred(struct cred *);
 extern void exit_creds(struct task_struct *);
-extern int copy_creds(struct task_struct *, unsigned long);
+extern int copy_creds(struct task_struct *, u64);
 extern const struct cred *get_task_cred(struct task_struct *);
 extern struct cred *cred_alloc_blank(void);
 extern struct cred *prepare_creds(void);
 extern struct cred *prepare_exec_creds(void);
 extern int commit_creds(struct cred *);
 extern void abort_creds(struct cred *);
-extern const struct cred *override_creds(const struct cred *);
-extern void revert_creds(const struct cred *);
 extern struct cred *prepare_kernel_cred(struct task_struct *);
+static inline const struct cred *kernel_cred(void)
+{
+	/* shut up sparse */
+	return rcu_dereference_raw(init_task.cred);
+}
 extern int set_security_override(struct cred *, u32);
 extern int set_security_override_from_ctx(struct cred *, const char *);
 extern int set_create_files_as(struct cred *, struct inode *);
@@ -172,49 +177,25 @@ static inline bool cap_ambient_invariant_ok(const struct cred *cred)
 					  cred->cap_inheritable));
 }
 
-/*
- * Override creds without bumping reference count. Caller must ensure
- * reference remains valid or has taken reference. Almost always not the
- * interface you want. Use override_creds()/revert_creds() instead.
- */
-static inline const struct cred *override_creds_light(const struct cred *override_cred)
+static inline const struct cred *override_creds(const struct cred *override_cred)
 {
-	const struct cred *old = current->cred;
-
-	rcu_assign_pointer(current->cred, override_cred);
-	return old;
+	return rcu_replace_pointer(current->cred, override_cred, 1);
 }
 
-static inline void revert_creds_light(const struct cred *revert_cred)
+static inline const struct cred *revert_creds(const struct cred *revert_cred)
 {
-	rcu_assign_pointer(current->cred, revert_cred);
+	return rcu_replace_pointer(current->cred, revert_cred, 1);
 }
 
-/**
- * get_new_cred_many - Get references on a new set of credentials
- * @cred: The new credentials to reference
- * @nr: Number of references to acquire
- *
- * Get references on the specified set of new credentials.  The caller must
- * release all acquired references.
- */
-static inline struct cred *get_new_cred_many(struct cred *cred, int nr)
-{
-	atomic_long_add(nr, &cred->usage);
-	return cred;
-}
+DEFINE_CLASS(override_creds,
+	     const struct cred *,
+	     revert_creds(_T),
+	     override_creds(override_cred), const struct cred *override_cred)
 
-/**
- * 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)
-{
-	return get_new_cred_many(cred, 1);
-}
+#define scoped_with_creds(cred) \
+	scoped_class(override_creds, __UNIQUE_ID(label), cred)
+
+#define scoped_with_kernel_creds() scoped_with_creds(kernel_cred())
 
 /**
  * get_cred_many - Get references on a set of credentials
@@ -236,7 +217,8 @@ static inline const struct cred *get_cred_many(const struct cred *cred, int nr)
 	if (!cred)
 		return cred;
 	nonconst_cred->non_rcu = 0;
-	return get_new_cred_many(nonconst_cred, nr);
+	atomic_long_add(nr, &nonconst_cred->usage);
+	return cred;
 }
 
 /*
@@ -298,6 +280,13 @@ static inline void put_cred(const struct cred *cred)
 	put_cred_many(cred, 1);
 }
 
+DEFINE_CLASS(prepare_creds,
+	      struct cred *,
+	      if (_T) put_cred(_T),
+	      prepare_creds(), void)
+
+DEFINE_FREE(put_cred, struct cred *, if (!IS_ERR_OR_NULL(_T)) put_cred(_T))
+
 /**
  * current_cred - Access the current task's subjective credentials
  *