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audit: Use rcu for task lookup protection

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Protect the task lookups in audit_receive_msg() with rcu_read_lock()
instead of tasklist_lock and use lock/unlock_sighand to protect
against the exit race.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Paris <eparis@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Thomas Gleixner 2009-12-09 14:19:41 +00:00 • committed by Al Viro
parent 207032051a
commit ab263f47c9
1 changed files with 14 additions and 16 deletions
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30
kernel/audit.c
View file

@ -873,17 +873,16 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
case AUDIT_TTY_GET: { case AUDIT_TTY_GET: {
struct audit_tty_status s; struct audit_tty_status s;
struct task_struct *tsk; struct task_struct *tsk;
unsigned long flags;
read_lock(&tasklist_lock); rcu_read_lock();
tsk = find_task_by_vpid(pid); tsk = find_task_by_vpid(pid);
if (!tsk) if (tsk && lock_task_sighand(tsk, &flags)) {
err = -ESRCH;
else {
spin_lock_irq(&tsk->sighand->siglock);
s.enabled = tsk->signal->audit_tty != 0; s.enabled = tsk->signal->audit_tty != 0;
spin_unlock_irq(&tsk->sighand->siglock); unlock_task_sighand(tsk, &flags);
} } else
read_unlock(&tasklist_lock); err = -ESRCH;
rcu_read_unlock();
if (!err) if (!err)
audit_send_reply(NETLINK_CB(skb).pid, seq, audit_send_reply(NETLINK_CB(skb).pid, seq,
@ -893,22 +892,21 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
case AUDIT_TTY_SET: { case AUDIT_TTY_SET: {
struct audit_tty_status *s; struct audit_tty_status *s;
struct task_struct *tsk; struct task_struct *tsk;
unsigned long flags;
if (nlh->nlmsg_len < sizeof(struct audit_tty_status)) if (nlh->nlmsg_len < sizeof(struct audit_tty_status))
return -EINVAL; return -EINVAL;
s = data; s = data;
if (s->enabled != 0 && s->enabled != 1) if (s->enabled != 0 && s->enabled != 1)
return -EINVAL; return -EINVAL;
read_lock(&tasklist_lock); rcu_read_lock();
tsk = find_task_by_vpid(pid); tsk = find_task_by_vpid(pid);
if (!tsk) if (tsk && lock_task_sighand(tsk, &flags)) {
err = -ESRCH;
else {
spin_lock_irq(&tsk->sighand->siglock);
tsk->signal->audit_tty = s->enabled != 0; tsk->signal->audit_tty = s->enabled != 0;
spin_unlock_irq(&tsk->sighand->siglock); unlock_task_sighand(tsk, &flags);
} } else
read_unlock(&tasklist_lock); err = -ESRCH;
rcu_read_unlock();
break; break;
} }
default: default: