Commit message: net: amend the fix for SO_BSDCOMPAT gsopt infoleak

The fix for CVE-2009-0676 (upstream commit df0bca04) is incomplete. Note
that the same problem of leaking kernel memory will reappear if someone
on some architecture uses struct timeval with some internal padding (for
example tv_sec 64-bit and tv_usec 32-bit) --- then, you are going to
leak the padded bytes to userspace.

Signed-off-by: Eugene Teo <eugeneteo@kernel.sg>
Reported-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
CVE: CVE-2009-0676
CWE: CWE-264
Vulnerability description: The sock_getsockopt function in net/core/sock.c in the Linux kernel before 2.6.28.6 does not initialize a certain structure member, which allows local users to obtain potentially sensitive information from kernel memory via an SO_BSDCOMPAT getsockopt request.

Project: linux-2.6

int sock_getsockopt(struct socket *sock, int level, int optname,
		    char __user *optval, int __user *optlen)
{
	struct sock *sk = sock->sk;

	union {
		int val;
		struct linger ling;
		struct timeval tm;
	} v;

	unsigned int lv = sizeof(int);
	int len;

	if (get_user(len, optlen))
		return -EFAULT;
	if (len < 0)
		return -EINVAL;

	v.val = 0;

	switch(optname) {
	case SO_DEBUG:
		v.val = sock_flag(sk, SOCK_DBG);
		break;

	case SO_DONTROUTE:
		v.val = sock_flag(sk, SOCK_LOCALROUTE);
		break;

	case SO_BROADCAST:
		v.val = !!sock_flag(sk, SOCK_BROADCAST);
		break;

	case SO_SNDBUF:
		v.val = sk->sk_sndbuf;
		break;

	case SO_RCVBUF:
		v.val = sk->sk_rcvbuf;
		break;

	case SO_REUSEADDR:
		v.val = sk->sk_reuse;
		break;

	case SO_KEEPALIVE:
		v.val = !!sock_flag(sk, SOCK_KEEPOPEN);
		break;

	case SO_TYPE:
		v.val = sk->sk_type;
		break;

	case SO_ERROR:
		v.val = -sock_error(sk);
		if (v.val==0)
			v.val = xchg(&sk->sk_err_soft, 0);
		break;

	case SO_OOBINLINE:
		v.val = !!sock_flag(sk, SOCK_URGINLINE);
		break;

	case SO_NO_CHECK:
		v.val = sk->sk_no_check;
		break;

	case SO_PRIORITY:
		v.val = sk->sk_priority;
		break;

	case SO_LINGER:
		lv		= sizeof(v.ling);
		v.ling.l_onoff	= !!sock_flag(sk, SOCK_LINGER);
		v.ling.l_linger	= sk->sk_lingertime / HZ;
		break;

	case SO_BSDCOMPAT:
		sock_warn_obsolete_bsdism("getsockopt");
		break;

	case SO_TIMESTAMP:
		v.val = sock_flag(sk, SOCK_RCVTSTAMP) &&
				!sock_flag(sk, SOCK_RCVTSTAMPNS);
		break;

	case SO_TIMESTAMPNS:
		v.val = sock_flag(sk, SOCK_RCVTSTAMPNS);
		break;

	case SO_RCVTIMEO:
		lv=sizeof(struct timeval);
		if (sk->sk_rcvtimeo == MAX_SCHEDULE_TIMEOUT) {
			v.tm.tv_sec = 0;
			v.tm.tv_usec = 0;
		} else {
			v.tm.tv_sec = sk->sk_rcvtimeo / HZ;
			v.tm.tv_usec = ((sk->sk_rcvtimeo % HZ) * 1000000) / HZ;
		}
		break;

	case SO_SNDTIMEO:
		lv=sizeof(struct timeval);
		if (sk->sk_sndtimeo == MAX_SCHEDULE_TIMEOUT) {
			v.tm.tv_sec = 0;
			v.tm.tv_usec = 0;
		} else {
			v.tm.tv_sec = sk->sk_sndtimeo / HZ;
			v.tm.tv_usec = ((sk->sk_sndtimeo % HZ) * 1000000) / HZ;
		}
		break;

	case SO_RCVLOWAT:
		v.val = sk->sk_rcvlowat;
		break;

	case SO_SNDLOWAT:
		v.val=1;
		break;

	case SO_PASSCRED:
		v.val = test_bit(SOCK_PASSCRED, &sock->flags) ? 1 : 0;
		break;

	case SO_PEERCRED:
		if (len > sizeof(sk->sk_peercred))
			len = sizeof(sk->sk_peercred);
		if (copy_to_user(optval, &sk->sk_peercred, len))
			return -EFAULT;
		goto lenout;

	case SO_PEERNAME:
	{
		char address[128];

		if (sock->ops->getname(sock, (struct sockaddr *)address, &lv, 2))
			return -ENOTCONN;
		if (lv < len)
			return -EINVAL;
		if (copy_to_user(optval, address, len))
			return -EFAULT;
		goto lenout;
	}

	/* Dubious BSD thing... Probably nobody even uses it, but
	 * the UNIX standard wants it for whatever reason... -DaveM
	 */
	case SO_ACCEPTCONN:
		v.val = sk->sk_state == TCP_LISTEN;
		break;

	case SO_PASSSEC:
		v.val = test_bit(SOCK_PASSSEC, &sock->flags) ? 1 : 0;
		break;

	case SO_PEERSEC:
		return security_socket_getpeersec_stream(sock, optval, optlen, len);

	case SO_MARK:
		v.val = sk->sk_mark;
		break;

	default:
		return -ENOPROTOOPT;
	}

	if (len > lv)
		len = lv;
	if (copy_to_user(optval, &v, len))
		return -EFAULT;
lenout:
	if (put_user(len, optlen))
		return -EFAULT;
	return 0;
}