Commit 49dffdfd authored by Vinicius Costa Gomes's avatar Vinicius Costa Gomes Committed by Amir Goldstein
Browse files

cred: Add a light version of override/revert_creds() 



Add a light version of override/revert_creds(), this should only be
used when the credentials in question will outlive the critical
section and the critical section doesn't change the ->usage of the
credentials.

Suggested-by: default avatarChristian Brauner <brauner@kernel.org>
Signed-off-by: default avatarVinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
parent 48b50624

include/linux/cred.h

+18 −0
Original line number Diff line number Diff line
@@ -172,6 +172,24 @@ 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)

{

	const struct cred *old = current->cred;



	rcu_assign_pointer(current->cred, override_cred);

	return old;

}



static inline void revert_creds_light(const struct cred *revert_cred)

{

	rcu_assign_pointer(current->cred, revert_cred);

}



/**

 * get_new_cred_many - Get references on a new set of credentials

 * @cred: The new credentials to reference

kernel/cred.c

+3 −3
Original line number Diff line number Diff line
@@ -485,7 +485,7 @@ EXPORT_SYMBOL(abort_creds); 
 */

const struct cred *override_creds(const struct cred *new)

{

	const struct cred *old = current->cred;

	const struct cred *old;



	kdebug("override_creds(%p{%ld})", new,

	       atomic_long_read(&new->usage));
@@ -499,7 +499,7 @@ const struct cred *override_creds(const struct cred *new) 
	 * visible to other threads under RCU.

	 */

	get_new_cred((struct cred *)new);

	rcu_assign_pointer(current->cred, new);

	old = override_creds_light(new);



	kdebug("override_creds() = %p{%ld}", old,

	       atomic_long_read(&old->usage));
@@ -521,7 +521,7 @@ void revert_creds(const struct cred *old) 
	kdebug("revert_creds(%p{%ld})", old,

	       atomic_long_read(&old->usage));



	rcu_assign_pointer(current->cred, old);

	revert_creds_light(old);

	put_cred(override);

}

EXPORT_SYMBOL(revert_creds);