Commit de248a75 authored by Pavel Emelyanov's avatar Pavel Emelyanov Committed by David S. Miller
Browse files

tcp repair: Fix unaligned access when repairing options (v2) 



Don't pick __u8/__u16 values directly from raw pointers, but instead use
an array of structures of code:value pairs. This is OK, since the buffer
we take options from is not an skb memory, but a user-to-kernel one.

For those options which don't require any value now, require this to be
zero (for potential future extension of this API).

v2: Changed tcp_repair_opt to use two __u32-s as spotted by David Laight.

Signed-off-by: default avatarPavel Emelyanov <xemul@parallels.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2d319508

include/linux/tcp.h

+5 −0
Original line number Diff line number Diff line
@@ -111,6 +111,11 @@ enum { 
#define TCP_QUEUE_SEQ		21

#define TCP_REPAIR_OPTIONS	22



struct tcp_repair_opt {

	__u32	opt_code;

	__u32	opt_val;

};



enum {

	TCP_NO_QUEUE,

	TCP_RECV_QUEUE,

net/ipv4/tcp.c

+21 −39
Original line number Diff line number Diff line
@@ -2283,60 +2283,40 @@ static inline int tcp_can_repair_sock(struct sock *sk) 
		((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_ESTABLISHED));

}



static int tcp_repair_options_est(struct tcp_sock *tp, char __user *optbuf, unsigned int len)

static int tcp_repair_options_est(struct tcp_sock *tp,

		struct tcp_repair_opt __user *optbuf, unsigned int len)

{

	/*

	 * Options are stored in CODE:VALUE form where CODE is 8bit and VALUE

	 * fits the respective TCPOLEN_ size

	 */



	while (len > 0) {

		u8 opcode;

	struct tcp_repair_opt opt;



		if (get_user(opcode, optbuf))

	while (len >= sizeof(opt)) {

		if (copy_from_user(&opt, optbuf, sizeof(opt)))

			return -EFAULT;



		optbuf++;

		len--;

		len -= sizeof(opt);



		switch (opcode) {

		case TCPOPT_MSS: {

			u16 in_mss;



			if (len < sizeof(in_mss))

				return -ENODATA;

			if (get_user(in_mss, optbuf))

				return -EFAULT;



			tp->rx_opt.mss_clamp = in_mss;



			optbuf += sizeof(in_mss);

			len -= sizeof(in_mss);

		switch (opt.opt_code) {

		case TCPOPT_MSS:

			tp->rx_opt.mss_clamp = opt.opt_val;

			break;

		}

		case TCPOPT_WINDOW: {

			u8 wscale;



			if (len < sizeof(wscale))

				return -ENODATA;

			if (get_user(wscale, optbuf))

				return -EFAULT;



			if (wscale > 14)

		case TCPOPT_WINDOW:

			if (opt.opt_val > 14)

				return -EFBIG;



			tp->rx_opt.snd_wscale = wscale;



			optbuf += sizeof(wscale);

			len -= sizeof(wscale);

			tp->rx_opt.snd_wscale = opt.opt_val;

			break;

		}

		case TCPOPT_SACK_PERM:

			if (opt.opt_val != 0)

				return -EINVAL;



			tp->rx_opt.sack_ok |= TCP_SACK_SEEN;

			if (sysctl_tcp_fack)

				tcp_enable_fack(tp);

			break;

		case TCPOPT_TIMESTAMP:

			if (opt.opt_val != 0)

				return -EINVAL;



			tp->rx_opt.tstamp_ok = 1;

			break;

		}
@@ -2557,7 +2537,9 @@ static int do_tcp_setsockopt(struct sock *sk, int level, 
		if (!tp->repair)

			err = -EINVAL;

		else if (sk->sk_state == TCP_ESTABLISHED)

			err = tcp_repair_options_est(tp, optval, optlen);

			err = tcp_repair_options_est(tp,

					(struct tcp_repair_opt __user *)optval,

					optlen);

		else

			err = -EPERM;

		break;

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