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authorDavid Howells <dhowells@redhat.com>2008-11-14 10:39:19 +1100
committerJames Morris <jmorris@namei.org>2008-11-14 10:39:19 +1100
commitc69e8d9c01db2adc503464993c358901c9af9de4 (patch)
treebed94aaa9aeb7a7834d1c880f72b62a11a752c78 /security/selinux/selinuxfs.c
parent86a264abe542cfececb4df129bc45a0338d8cdb9 (diff)
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CRED: Use RCU to access another task's creds and to release a task's own creds
Use RCU to access another task's creds and to release a task's own creds. This means that it will be possible for the credentials of a task to be replaced without another task (a) requiring a full lock to read them, and (b) seeing deallocated memory. 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>
Diffstat (limited to 'security/selinux/selinuxfs.c')
-rw-r--r--security/selinux/selinuxfs.c13
1 files changed, 9 insertions, 4 deletions
diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index 10715d1330b..c8630363823 100644
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -95,13 +95,18 @@ extern void selnl_notify_setenforce(int val);
static int task_has_security(struct task_struct *tsk,
u32 perms)
{
- struct task_security_struct *tsec;
-
- tsec = tsk->cred->security;
+ const struct task_security_struct *tsec;
+ u32 sid = 0;
+
+ rcu_read_lock();
+ tsec = __task_cred(tsk)->security;
+ if (tsec)
+ sid = tsec->sid;
+ rcu_read_unlock();
if (!tsec)
return -EACCES;
- return avc_has_perm(tsec->sid, SECINITSID_SECURITY,
+ return avc_has_perm(sid, SECINITSID_SECURITY,
SECCLASS_SECURITY, perms, NULL);
}