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tty: audit: Handle tty audit enable atomically

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The audit_tty and audit_tty_log_passwd fields are actually bool
values, so merge into single memory location to access atomically.

NB: audit log operations may still occur after tty audit is disabled
which is consistent with the existing functionality

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Hurley
2016-01-09 22:55:33 -08:00
committed by Greg Kroah-Hartman
parent 4d240b6442
commit 2e28d38ae1
4 changed files with 38 additions and 45 deletions
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25
kernel/audit.c
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@@ -1030,20 +1030,19 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
break;
case AUDIT_TTY_GET: {
struct audit_tty_status s;
struct task_struct *tsk = current;
unsigned int t;
spin_lock(&tsk->sighand->siglock);
s.enabled = tsk->signal->audit_tty;
s.log_passwd = tsk->signal->audit_tty_log_passwd;
spin_unlock(&tsk->sighand->siglock);
t = READ_ONCE(current->signal->audit_tty);
s.enabled = t & AUDIT_TTY_ENABLE;
s.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
audit_send_reply(skb, seq, AUDIT_TTY_GET, 0, 0, &s, sizeof(s));
break;
}
case AUDIT_TTY_SET: {
struct audit_tty_status s, old;
struct task_struct *tsk = current;
struct audit_buffer *ab;
unsigned int t;
memset(&s, 0, sizeof(s));
/* guard against past and future API changes */
@@ -1053,14 +1052,14 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
(s.log_passwd != 0 && s.log_passwd != 1))
err = -EINVAL;
spin_lock(&tsk->sighand->siglock);
old.enabled = tsk->signal->audit_tty;
old.log_passwd = tsk->signal->audit_tty_log_passwd;
if (!err) {
tsk->signal->audit_tty = s.enabled;
tsk->signal->audit_tty_log_passwd = s.log_passwd;
if (err)
t = READ_ONCE(current->signal->audit_tty);
else {
t = s.enabled | (-s.log_passwd & AUDIT_TTY_LOG_PASSWD);
t = xchg(&current->signal->audit_tty, t);
}
spin_unlock(&tsk->sighand->siglock);
old.enabled = t & AUDIT_TTY_ENABLE;
old.log_passwd = !!(t & AUDIT_TTY_LOG_PASSWD);
audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
audit_log_format(ab, " op=tty_set old-enabled=%d new-enabled=%d"