LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: pierre.peiffer@bull.net
To: linux-kernel@vger.kernel.org, containers@lists.linux-foundation.org
Subject: [PATCH 2.6.24-rc8-mm1 03/15] IPC/message queues: introduce msgctl_down
Date: Tue, 29 Jan 2008 17:02:32 +0100	[thread overview]
Message-ID: <20080129161656.894516650@bull.net> (raw)
In-Reply-To: <20080129160229.612172683@bull.net>

[-- Attachment #1: ipc_introduce_msgctl_down.patch --]
[-- Type: text/plain, Size: 5012 bytes --]

From: Pierre Peiffer <pierre.peiffer@bull.net>

Currently, sys_msgctl is not easy to read.
This patch tries to improve that by introducing the msgctl_down function
to handle all commands requiring the rwmutex to be taken in write mode
(ie IPC_SET and IPC_RMID for now). It is the equivalent function of
semctl_down for message queues.

This greatly changes the readability of sys_msgctl and also harmonizes
the way these commands are handled among all IPCs.


Signed-off-by: Pierre Peiffer <pierre.peiffer@bull.net>
Acked-by: Serge Hallyn <serue@us.ibm.com>
---

 ipc/msg.c |  162 ++++++++++++++++++++++++++++++++++----------------------------
 1 file changed, 89 insertions(+), 73 deletions(-)

Index: b/ipc/msg.c
===================================================================
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -399,10 +399,95 @@ copy_msqid_from_user(struct msq_setbuf *
 	}
 }
 
-asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
+/*
+ * This function handles some msgctl commands which require the rw_mutex
+ * to be held in write mode.
+ * NOTE: no locks must be held, the rw_mutex is taken inside this function.
+ */
+static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
+		       struct msqid_ds __user *buf, int version)
 {
 	struct kern_ipc_perm *ipcp;
-	struct msq_setbuf uninitialized_var(setbuf);
+	struct msq_setbuf setbuf;
+	struct msg_queue *msq;
+	int err;
+
+	if (cmd == IPC_SET) {
+		if (copy_msqid_from_user(&setbuf, buf, version))
+			return -EFAULT;
+	}
+
+	down_write(&msg_ids(ns).rw_mutex);
+	msq = msg_lock_check_down(ns, msqid);
+	if (IS_ERR(msq)) {
+		err = PTR_ERR(msq);
+		goto out_up;
+	}
+
+	ipcp = &msq->q_perm;
+
+	err = audit_ipc_obj(ipcp);
+	if (err)
+		goto out_unlock;
+
+	if (cmd == IPC_SET) {
+		err = audit_ipc_set_perm(setbuf.qbytes, setbuf.uid, setbuf.gid,
+					 setbuf.mode);
+		if (err)
+			goto out_unlock;
+	}
+
+	if (current->euid != ipcp->cuid &&
+	    current->euid != ipcp->uid &&
+	    !capable(CAP_SYS_ADMIN)) {
+		/* We _could_ check for CAP_CHOWN above, but we don't */
+		err = -EPERM;
+		goto out_unlock;
+	}
+
+	err = security_msg_queue_msgctl(msq, cmd);
+	if (err)
+		goto out_unlock;
+
+	switch (cmd) {
+	case IPC_RMID:
+		freeque(ns, ipcp);
+		goto out_up;
+	case IPC_SET:
+		if (setbuf.qbytes > ns->msg_ctlmnb &&
+		    !capable(CAP_SYS_RESOURCE)) {
+			err = -EPERM;
+			goto out_unlock;
+		}
+
+		msq->q_qbytes = setbuf.qbytes;
+
+		ipcp->uid = setbuf.uid;
+		ipcp->gid = setbuf.gid;
+		ipcp->mode = (ipcp->mode & ~S_IRWXUGO) |
+			     (S_IRWXUGO & setbuf.mode);
+		msq->q_ctime = get_seconds();
+		/* sleeping receivers might be excluded by
+		 * stricter permissions.
+		 */
+		expunge_all(msq, -EAGAIN);
+		/* sleeping senders might be able to send
+		 * due to a larger queue size.
+		 */
+		ss_wakeup(&msq->q_senders, 0);
+		break;
+	default:
+		err = -EINVAL;
+	}
+out_unlock:
+	msg_unlock(msq);
+out_up:
+	up_write(&msg_ids(ns).rw_mutex);
+	return err;
+}
+
+asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
+{
 	struct msg_queue *msq;
 	int err, version;
 	struct ipc_namespace *ns;
@@ -498,82 +583,13 @@ asmlinkage long sys_msgctl(int msqid, in
 		return success_return;
 	}
 	case IPC_SET:
-		if (!buf)
-			return -EFAULT;
-		if (copy_msqid_from_user(&setbuf, buf, version))
-			return -EFAULT;
-		break;
 	case IPC_RMID:
-		break;
+		err = msgctl_down(ns, msqid, cmd, buf, version);
+		return err;
 	default:
 		return  -EINVAL;
 	}
 
-	down_write(&msg_ids(ns).rw_mutex);
-	msq = msg_lock_check_down(ns, msqid);
-	if (IS_ERR(msq)) {
-		err = PTR_ERR(msq);
-		goto out_up;
-	}
-
-	ipcp = &msq->q_perm;
-
-	err = audit_ipc_obj(ipcp);
-	if (err)
-		goto out_unlock_up;
-	if (cmd == IPC_SET) {
-		err = audit_ipc_set_perm(setbuf.qbytes, setbuf.uid, setbuf.gid,
-					 setbuf.mode);
-		if (err)
-			goto out_unlock_up;
-	}
-
-	err = -EPERM;
-	if (current->euid != ipcp->cuid &&
-	    current->euid != ipcp->uid && !capable(CAP_SYS_ADMIN))
-		/* We _could_ check for CAP_CHOWN above, but we don't */
-		goto out_unlock_up;
-
-	err = security_msg_queue_msgctl(msq, cmd);
-	if (err)
-		goto out_unlock_up;
-
-	switch (cmd) {
-	case IPC_SET:
-	{
-		err = -EPERM;
-		if (setbuf.qbytes > ns->msg_ctlmnb && !capable(CAP_SYS_RESOURCE))
-			goto out_unlock_up;
-
-		msq->q_qbytes = setbuf.qbytes;
-
-		ipcp->uid = setbuf.uid;
-		ipcp->gid = setbuf.gid;
-		ipcp->mode = (ipcp->mode & ~S_IRWXUGO) |
-			     (S_IRWXUGO & setbuf.mode);
-		msq->q_ctime = get_seconds();
-		/* sleeping receivers might be excluded by
-		 * stricter permissions.
-		 */
-		expunge_all(msq, -EAGAIN);
-		/* sleeping senders might be able to send
-		 * due to a larger queue size.
-		 */
-		ss_wakeup(&msq->q_senders, 0);
-		msg_unlock(msq);
-		break;
-	}
-	case IPC_RMID:
-		freeque(ns, &msq->q_perm);
-		break;
-	}
-	err = 0;
-out_up:
-	up_write(&msg_ids(ns).rw_mutex);
-	return err;
-out_unlock_up:
-	msg_unlock(msq);
-	goto out_up;
 out_unlock:
 	msg_unlock(msq);
 	return err;

-- 
Pierre Peiffer

  parent reply	other threads:[~2008-01-29 16:17 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-29 16:02 [PATCH 2.6.24-rc8-mm1 00/15] IPC: code rewrite + new functionalities pierre.peiffer
2008-01-29 16:02 ` [PATCH 2.6.24-rc8-mm1 01/15] IPC/semaphores: code factorisation pierre.peiffer
2008-01-29 16:02 ` [PATCH 2.6.24-rc8-mm1 02/15] IPC/shared memory: introduce shmctl_down pierre.peiffer
2008-01-29 16:02 ` pierre.peiffer [this message]
2008-01-29 16:02 ` [PATCH 2.6.24-rc8-mm1 04/15] IPC/semaphores: move the rwmutex handling inside semctl_down pierre.peiffer
2008-01-29 16:02 ` [PATCH 2.6.24-rc8-mm1 05/15] IPC/semaphores: remove one unused parameter from semctl_down() pierre.peiffer
2008-01-31  8:32   ` Nadia Derbey
2008-01-31 10:18     ` Pierre Peiffer
2008-01-31 11:30       ` Nadia Derbey
2008-01-29 16:02 ` [PATCH 2.6.24-rc8-mm1 06/15] IPC: get rid of the use *_setbuf structure pierre.peiffer
2008-01-29 16:02 ` [PATCH 2.6.24-rc8-mm1 07/15] IPC: introduce ipc_update_perm() pierre.peiffer
2008-01-29 16:02 ` [PATCH 2.6.24-rc8-mm1 08/15] IPC: consolidate all xxxctl_down() functions pierre.peiffer
2008-01-29 16:02 ` [PATCH 2.6.24-rc8-mm1 09/15] (RFC) IPC: new kernel API to change an ID pierre.peiffer
2008-01-29 21:06   ` Alexey Dobriyan
2008-01-30  9:52     ` Pierre Peiffer
2008-01-31  9:00     ` Pierre Peiffer
2008-01-31  9:54       ` Kirill Korotaev
2008-01-31 11:57         ` Pierre Peiffer
2008-01-31 13:11           ` Kirill Korotaev
2008-01-31 16:10             ` Cedric Le Goater
2008-02-04 13:41               ` Kirill Korotaev
2008-02-04 14:06                 ` [Devel] " Pavel Emelyanov
2008-02-04 15:00                   ` Daniel Lezcano
2008-02-04 15:16                     ` Pavel Emelyanov
2008-02-05  9:51           ` Oren Laadan
2008-02-05 18:00             ` Dave Hansen
2008-02-05 18:42             ` Serge E. Hallyn
2008-02-06  2:07               ` Oren Laadan
2008-02-06  5:00                 ` Serge E. Hallyn
2008-02-08 10:12               ` Pierre Peiffer
2008-01-29 16:02 ` [PATCH 2.6.24-rc8-mm1 10/15] (RFC) IPC: new IPC_SETID command to modify " pierre.peiffer
2008-01-29 16:02 ` [PATCH 2.6.24-rc8-mm1 11/15] (RFC) IPC: new IPC_SETALL command to modify all settings pierre.peiffer
2008-01-29 16:02 ` [PATCH 2.6.24-rc8-mm1 12/15] (RFC) IPC/semaphores: make use of RCU to free the sem_undo_list pierre.peiffer
2008-01-30 21:26   ` Serge E. Hallyn
2008-01-31  9:52     ` Pierre Peiffer
2008-01-29 16:02 ` [PATCH 2.6.24-rc8-mm1 13/15] (RFC) IPC/semaphores: per <pid> semundo file in procfs pierre.peiffer
2008-01-29 16:02 ` [PATCH 2.6.24-rc8-mm1 14/15] (RFC) IPC/semaphores: prepare semundo code to work on another task than current pierre.peiffer
2008-01-30 21:44   ` Serge E. Hallyn
2008-01-31  9:48     ` Pierre Peiffer
2008-01-31 18:01       ` Serge E. Hallyn
2008-02-01 12:09         ` Pierre Peiffer
2008-01-29 16:02 ` [PATCH 2.6.24-rc8-mm1 15/15] (RFC) IPC/semaphores: add write() operation to semundo file in procfs pierre.peiffer
2008-02-02 18:23 ` [PATCH 2.6.24-rc8-mm1 00/15] IPC: code rewrite + new functionalities Pavel Machek
2008-02-04 13:52   ` Pierre Peiffer
2008-02-04 15:44   ` Benjamin Thery
2008-02-04 19:51     ` Pavel Machek

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20080129161656.894516650@bull.net \
    --to=pierre.peiffer@bull.net \
    --cc=containers@lists.linux-foundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --subject='Re: [PATCH 2.6.24-rc8-mm1 03/15] IPC/message queues: introduce msgctl_down' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).