From 107b413cd33374f8eb3a0075d0237e1076e0a752 Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Mon, 8 Jul 2013 16:01:16 -0700 Subject: ipc,msg: make msgctl_nolock lockless commit ac0ba20ea6f2201a1589d6dc26ad1a4f0f967bb8 upstream. While the INFO cmd doesn't take the ipc lock, the STAT commands do acquire it unnecessarily. We can do the permissions and security checks only holding the rcu lock. This function now mimics semctl_nolock(). Signed-off-by: Davidlohr Bueso Cc: Andi Kleen Cc: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Cc: Mike Galbraith Signed-off-by: Greg Kroah-Hartman --- ipc/msg.c | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-) (limited to 'ipc') diff --git a/ipc/msg.c b/ipc/msg.c index 4e8cf7b94344..c0fe57cc39fc 100644 --- a/ipc/msg.c +++ b/ipc/msg.c @@ -545,17 +545,25 @@ static int msgctl_nolock(struct ipc_namespace *ns, int msqid, if (!buf) return -EFAULT; + memset(&tbuf, 0, sizeof(tbuf)); + + rcu_read_lock(); if (cmd == MSG_STAT) { - msq = msg_lock(ns, msqid); - if (IS_ERR(msq)) - return PTR_ERR(msq); + msq = msq_obtain_object(ns, msqid); + if (IS_ERR(msq)) { + err = PTR_ERR(msq); + goto out_unlock; + } success_return = msq->q_perm.id; } else { - msq = msg_lock_check(ns, msqid); - if (IS_ERR(msq)) - return PTR_ERR(msq); + msq = msq_obtain_object_check(ns, msqid); + if (IS_ERR(msq)) { + err = PTR_ERR(msq); + goto out_unlock; + } success_return = 0; } + err = -EACCES; if (ipcperms(ns, &msq->q_perm, S_IRUGO)) goto out_unlock; @@ -564,8 +572,6 @@ static int msgctl_nolock(struct ipc_namespace *ns, int msqid, if (err) goto out_unlock; - memset(&tbuf, 0, sizeof(tbuf)); - kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm); tbuf.msg_stime = msq->q_stime; tbuf.msg_rtime = msq->q_rtime; @@ -575,7 +581,8 @@ static int msgctl_nolock(struct ipc_namespace *ns, int msqid, tbuf.msg_qbytes = msq->q_qbytes; tbuf.msg_lspid = msq->q_lspid; tbuf.msg_lrpid = msq->q_lrpid; - msg_unlock(msq); + rcu_read_unlock(); + if (copy_msqid_to_user(buf, &tbuf, version)) return -EFAULT; return success_return; @@ -587,7 +594,7 @@ static int msgctl_nolock(struct ipc_namespace *ns, int msqid, return err; out_unlock: - msg_unlock(msq); + rcu_read_unlock(); return err; } -- cgit v1.2.3