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audit: use spin_lock_irqsave/restore in audit tty code
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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: Eric Paris <[email protected]>
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@eparis
eparis committed Apr 30, 2013
1 parent 4d3fb70 commit bde02ca
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Showing 2 changed files with 25 additions and 17 deletions.
32 changes: 19 additions & 13 deletions drivers/tty/tty_audit.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;

Expand All @@ -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);
}

/**
Expand All @@ -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;
Expand Down Expand Up @@ -221,18 +225,19 @@ 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;
if (buf) {
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,
Expand All @@ -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;
Expand All @@ -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;
Expand Down Expand Up @@ -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;
Expand Down
10 changes: 6 additions & 4 deletions kernel/audit.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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));
Expand All @@ -816,16 +817,17 @@ 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;
s = data;
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:
Expand Down

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