Commit bde02ca8 authored by Eric Paris's avatar Eric Paris
Browse files

audit: use spin_lock_irqsave/restore in audit tty code 



Some of the callers of the audit tty function use spin_lock_irqsave/restore.
We were using the forced always enable version, which seems really bad.
Since I don't know every one of these code paths well enough, it makes
sense to just switch everything to the safe version.  Maybe it's a
little overzealous, but it's a lot better than an unlucky deadlock when
we return to a caller with irq enabled and they expect it to be
disabled.

Signed-off-by: default avatarEric Paris <eparis@redhat.com>
parent 4d3fb709

drivers/tty/tty_audit.c

+19 −13
Original line number Diff line number Diff line
@@ -111,11 +111,12 @@ static void tty_audit_buf_push(struct tty_audit_buf *buf) 
void tty_audit_exit(void)

{

	struct tty_audit_buf *buf;

	unsigned long flags;



	spin_lock_irq(&current->sighand->siglock);

	spin_lock_irqsave(&current->sighand->siglock, flags);

	buf = current->signal->tty_audit_buf;

	current->signal->tty_audit_buf = NULL;

	spin_unlock_irq(&current->sighand->siglock);

	spin_unlock_irqrestore(&current->sighand->siglock, flags);

	if (!buf)

		return;
@@ -133,9 +134,11 @@ void tty_audit_exit(void) 
 */

void tty_audit_fork(struct signal_struct *sig)

{

	spin_lock_irq(&current->sighand->siglock);

	unsigned long flags;



	spin_lock_irqsave(&current->sighand->siglock, flags);

	sig->audit_tty = current->signal->audit_tty;

	spin_unlock_irq(&current->sighand->siglock);

	spin_unlock_irqrestore(&current->sighand->siglock, flags);

}



/**
@@ -145,13 +148,14 @@ void tty_audit_tiocsti(struct tty_struct *tty, char ch) 
{

	struct tty_audit_buf *buf;

	int major, minor, should_audit;

	unsigned long flags;



	spin_lock_irq(&current->sighand->siglock);

	spin_lock_irqsave(&current->sighand->siglock, flags);

	should_audit = current->signal->audit_tty;

	buf = current->signal->tty_audit_buf;

	if (buf)

		atomic_inc(&buf->count);

	spin_unlock_irq(&current->sighand->siglock);

	spin_unlock_irqrestore(&current->sighand->siglock, flags);



	major = tty->driver->major;

	minor = tty->driver->minor_start + tty->index;
@@ -221,10 +225,11 @@ static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty, 
		unsigned icanon)

{

	struct tty_audit_buf *buf, *buf2;

	unsigned long flags;



	buf = NULL;

	buf2 = NULL;

	spin_lock_irq(&current->sighand->siglock);

	spin_lock_irqsave(&current->sighand->siglock, flags);

	if (likely(!current->signal->audit_tty))

		goto out;

	buf = current->signal->tty_audit_buf;
@@ -232,7 +237,7 @@ static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty, 
		atomic_inc(&buf->count);

		goto out;

	}

	spin_unlock_irq(&current->sighand->siglock);

	spin_unlock_irqrestore(&current->sighand->siglock, flags);



	buf2 = tty_audit_buf_alloc(tty->driver->major,

				   tty->driver->minor_start + tty->index,
@@ -242,7 +247,7 @@ static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty, 
		return NULL;

	}



	spin_lock_irq(&current->sighand->siglock);

	spin_lock_irqsave(&current->sighand->siglock, flags);

	if (!current->signal->audit_tty)

		goto out;

	buf = current->signal->tty_audit_buf;
@@ -254,7 +259,7 @@ static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty, 
	atomic_inc(&buf->count);

	/* Fall through */

 out:

	spin_unlock_irq(&current->sighand->siglock);

	spin_unlock_irqrestore(&current->sighand->siglock, flags);

	if (buf2)

		tty_audit_buf_free(buf2);

	return buf;
@@ -317,16 +322,17 @@ void tty_audit_add_data(struct tty_struct *tty, unsigned char *data, 
void tty_audit_push(struct tty_struct *tty)

{

	struct tty_audit_buf *buf;

	unsigned long flags;



	spin_lock_irq(&current->sighand->siglock);

	spin_lock_irqsave(&current->sighand->siglock, flags);

	if (likely(!current->signal->audit_tty)) {

		spin_unlock_irq(&current->sighand->siglock);

		spin_unlock_irqrestore(&current->sighand->siglock, flags);

		return;

	}

	buf = current->signal->tty_audit_buf;

	if (buf)

		atomic_inc(&buf->count);

	spin_unlock_irq(&current->sighand->siglock);

	spin_unlock_irqrestore(&current->sighand->siglock, flags);



	if (buf) {

		int major, minor;

kernel/audit.c

+6 −4
Original line number Diff line number Diff line
@@ -804,10 +804,11 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) 
	case AUDIT_TTY_GET: {

		struct audit_tty_status s;

		struct task_struct *tsk = current;

		unsigned long flags;



		spin_lock_irq(&tsk->sighand->siglock);

		spin_lock_irqsave(&tsk->sighand->siglock, flags);

		s.enabled = tsk->signal->audit_tty != 0;

		spin_unlock_irq(&tsk->sighand->siglock);

		spin_unlock_irqrestore(&tsk->sighand->siglock, flags);



		audit_send_reply(NETLINK_CB(skb).portid, seq,

				 AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
@@ -816,6 +817,7 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) 
	case AUDIT_TTY_SET: {

		struct audit_tty_status *s;

		struct task_struct *tsk = current;

		unsigned long flags;



		if (nlh->nlmsg_len < sizeof(struct audit_tty_status))

			return -EINVAL;
@@ -823,9 +825,9 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) 
		if (s->enabled != 0 && s->enabled != 1)

			return -EINVAL;



		spin_lock_irq(&tsk->sighand->siglock);

		spin_lock_irqsave(&tsk->sighand->siglock, flags);

		tsk->signal->audit_tty = s->enabled != 0;

		spin_unlock_irq(&tsk->sighand->siglock);

		spin_unlock_irqrestore(&tsk->sighand->siglock, flags);

		break;

	}

	default:

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