Commit 723a0043 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'l2tp-mtu' 



Guillaume Nault says:

====================
l2tp: sanitise MTU handling on sessions

Most of the code handling sessions' MTU has no effect. The ->mtu field
in struct l2tp_session might be used at session creation time, but
neither PPP nor Ethernet pseudo-wires take updates into account.

L2TP sessions don't have a concept of MTU, which is the reason why
->mtu is mostly ignored. MTU should remain a network device thing.
Therefore this patch set does not try to propagate/update ->mtu to/from
the device. That would complicate the code unnecessarily. Instead this
field and the associated ioctl commands and netlink attributes are
removed.

Patch #1 defines l2tp_tunnel_dst_mtu() in order to simplify the
following patches. Then patches #2 and #3 remove MTU handling from PPP
and Ethernet pseudo-wires respectively.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents f3184645 e9697e2e

include/uapi/linux/l2tp.h

+1 −1
Original line number Diff line number Diff line
@@ -119,7 +119,7 @@ enum { 
	L2TP_ATTR_IP_DADDR,		/* u32 */

	L2TP_ATTR_UDP_SPORT,		/* u16 */

	L2TP_ATTR_UDP_DPORT,		/* u16 */

	L2TP_ATTR_MTU,			/* u16 */

	L2TP_ATTR_MTU,			/* u16 (not used) */

	L2TP_ATTR_MRU,			/* u16 (not used) */

	L2TP_ATTR_STATS,		/* nested */

	L2TP_ATTR_IP6_SADDR,		/* struct in6_addr */

net/l2tp/l2tp_core.c

+0 −1
Original line number Diff line number Diff line
@@ -1674,7 +1674,6 @@ struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunn 
		if (cfg) {

			session->pwtype = cfg->pw_type;

			session->debug = cfg->debug;

			session->mtu = cfg->mtu;

			session->send_seq = cfg->send_seq;

			session->recv_seq = cfg->recv_seq;

			session->lns_mode = cfg->lns_mode;

net/l2tp/l2tp_core.h

+18 −2
Original line number Diff line number Diff line
@@ -12,6 +12,9 @@ 
#ifndef _L2TP_CORE_H_

#define _L2TP_CORE_H_



#include <net/dst.h>

#include <net/sock.h>



/* Just some random numbers */

#define L2TP_TUNNEL_MAGIC	0x42114DDA

#define L2TP_SESSION_MAGIC	0x0C04EB7D
@@ -61,7 +64,6 @@ struct l2tp_session_cfg { 
	int			peer_cookie_len; /* 0, 4 or 8 bytes */

	int			reorder_timeout; /* configured reorder timeout

						  * (in jiffies) */

	int			mtu;

	char			*ifname;

};
@@ -105,7 +107,6 @@ struct l2tp_session { 
	int			reorder_timeout; /* configured reorder timeout

						  * (in jiffies) */

	int			reorder_skip;	/* set if skip to next nr */

	int			mtu;

	enum l2tp_pwtype	pwtype;

	struct l2tp_stats	stats;

	struct hlist_node	global_hlist;	/* Global hash list node */
@@ -268,6 +269,21 @@ static inline int l2tp_get_l2specific_len(struct l2tp_session *session) 
	}

}



static inline u32 l2tp_tunnel_dst_mtu(const struct l2tp_tunnel *tunnel)

{

	struct dst_entry *dst;

	u32 mtu;



	dst = sk_dst_get(tunnel->sock);

	if (!dst)

		return 0;



	mtu = dst_mtu(dst);

	dst_release(dst);



	return mtu;

}



#define l2tp_printk(ptr, type, func, fmt, ...)				\

do {									\

	if (((ptr)->debug) & (type))					\

net/l2tp/l2tp_debugfs.c

+1 −2
Original line number Diff line number Diff line
@@ -191,8 +191,7 @@ static void l2tp_dfs_seq_session_show(struct seq_file *m, void *v) 
	if (session->send_seq || session->recv_seq)

		seq_printf(m, "   nr %hu, ns %hu\n", session->nr, session->ns);

	seq_printf(m, "   refcnt %d\n", refcount_read(&session->ref_count));

	seq_printf(m, "   config %d/0/%c/%c/-/%s %08x %u\n",

		   session->mtu,

	seq_printf(m, "   config 0/0/%c/%c/-/%s %08x %u\n",

		   session->recv_seq ? 'R' : '-',

		   session->send_seq ? 'S' : '-',

		   session->lns_mode ? "LNS" : "LAC",

net/l2tp/l2tp_eth.c

+8 −17
Original line number Diff line number Diff line
@@ -226,22 +226,19 @@ static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel, 
				struct net_device *dev)

{

	unsigned int overhead = 0;

	struct dst_entry *dst;

	u32 l3_overhead = 0;

	u32 mtu;



	/* if the encap is UDP, account for UDP header size */

	if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {

		overhead += sizeof(struct udphdr);

		dev->needed_headroom += sizeof(struct udphdr);

	}

	if (session->mtu != 0) {

		dev->mtu = session->mtu;

		dev->needed_headroom += session->hdr_len;

		return;

	}



	lock_sock(tunnel->sock);

	l3_overhead = kernel_sock_ip_overhead(tunnel->sock);

	release_sock(tunnel->sock);



	if (l3_overhead == 0) {

		/* L3 Overhead couldn't be identified, this could be

		 * because tunnel->sock was NULL or the socket's
@@ -255,18 +252,12 @@ static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel, 
	 */

	overhead += session->hdr_len + ETH_HLEN + l3_overhead;



	/* If PMTU discovery was enabled, use discovered MTU on L2TP device */

	dst = sk_dst_get(tunnel->sock);

	if (dst) {

		/* dst_mtu will use PMTU if found, else fallback to intf MTU */

		u32 pmtu = dst_mtu(dst);

	mtu = l2tp_tunnel_dst_mtu(tunnel) - overhead;

	if (mtu < dev->min_mtu || mtu > dev->max_mtu)

		dev->mtu = ETH_DATA_LEN - overhead;

	else

		dev->mtu = mtu;



		if (pmtu != 0)

			dev->mtu = pmtu;

		dst_release(dst);

	}

	session->mtu = dev->mtu - overhead;

	dev->mtu = session->mtu;

	dev->needed_headroom += session->hdr_len;

}

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