Commit 374edea4 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'ip6_gre-Fixes-in-headroom-handling' 



Petr Machata says:

====================
net: ip6_gre: Fixes in headroom handling

This series mends some problems in headroom management in ip6_gre
module. The current code base has the following three closely-related
problems:

- ip6gretap tunnels neglect to ensure there's enough writable headroom
  before pushing GRE headers.

- ip6erspan does this, but assumes that dev->needed_headroom is primed.
  But that doesn't happen until ip6_tnl_xmit() is called later. Thus for
  the first packet, ip6erspan actually behaves like ip6gretap above.

- ip6erspan shares some of the code with ip6gretap, including
  calculations of needed header length. While there is custom
  ERSPAN-specific code for calculating the headroom, the computed
  values are overwritten by the ip6gretap code.

The first two issues lead to a kernel panic in situations where a packet
is mirrored from a veth device to the device in question. They are
fixed, respectively, in patches #1 and #2, which include the full panic
trace and a reproducer.

The rest of the patchset deals with the last issue. In patches #3 to #6,
several functions are split up into reusable parts. Finally in patch #7
these blocks are used to compose ERSPAN-specific callbacks where
necessary to fix the hlen calculation.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 02f99df1 2d665034

net/ipv6/ip6_gre.c

+145 −39
Original line number Diff line number Diff line
@@ -81,6 +81,7 @@ static int ip6gre_tunnel_init(struct net_device *dev); 
static void ip6gre_tunnel_setup(struct net_device *dev);

static void ip6gre_tunnel_link(struct ip6gre_net *ign, struct ip6_tnl *t);

static void ip6gre_tnl_link_config(struct ip6_tnl *t, int set_mtu);

static void ip6erspan_tnl_link_config(struct ip6_tnl *t, int set_mtu);



/* Tunnel hash table */
@@ -698,6 +699,9 @@ static netdev_tx_t __gre6_xmit(struct sk_buff *skb, 
	else

		fl6->daddr = tunnel->parms.raddr;



	if (skb_cow_head(skb, dev->needed_headroom ?: tunnel->hlen))

		return -ENOMEM;



	/* Push GRE header. */

	protocol = (dev->type == ARPHRD_ETHER) ? htons(ETH_P_TEB) : proto;
@@ -908,7 +912,7 @@ static netdev_tx_t ip6erspan_tunnel_xmit(struct sk_buff *skb, 
		truncate = true;

	}



	if (skb_cow_head(skb, dev->needed_headroom))

	if (skb_cow_head(skb, dev->needed_headroom ?: t->hlen))

		goto tx_err;



	t->parms.o_flags &= ~TUNNEL_KEY;
@@ -1022,12 +1026,11 @@ tx_err: 
	return NETDEV_TX_OK;

}



static void ip6gre_tnl_link_config(struct ip6_tnl *t, int set_mtu)

static void ip6gre_tnl_link_config_common(struct ip6_tnl *t)

{

	struct net_device *dev = t->dev;

	struct __ip6_tnl_parm *p = &t->parms;

	struct flowi6 *fl6 = &t->fl.u.ip6;

	int t_hlen;



	if (dev->type != ARPHRD_ETHER) {

		memcpy(dev->dev_addr, &p->laddr, sizeof(struct in6_addr));
@@ -1054,12 +1057,13 @@ static void ip6gre_tnl_link_config(struct ip6_tnl *t, int set_mtu) 
		dev->flags |= IFF_POINTOPOINT;

	else

		dev->flags &= ~IFF_POINTOPOINT;

}



	t->tun_hlen = gre_calc_hlen(t->parms.o_flags);



	t->hlen = t->encap_hlen + t->tun_hlen;



	t_hlen = t->hlen + sizeof(struct ipv6hdr);

static void ip6gre_tnl_link_config_route(struct ip6_tnl *t, int set_mtu,

					 int t_hlen)

{

	const struct __ip6_tnl_parm *p = &t->parms;

	struct net_device *dev = t->dev;



	if (p->flags & IP6_TNL_F_CAP_XMIT) {

		int strict = (ipv6_addr_type(&p->raddr) &
@@ -1091,8 +1095,26 @@ static void ip6gre_tnl_link_config(struct ip6_tnl *t, int set_mtu) 
	}

}



static int ip6gre_tnl_change(struct ip6_tnl *t,

	const struct __ip6_tnl_parm *p, int set_mtu)

static int ip6gre_calc_hlen(struct ip6_tnl *tunnel)

{

	int t_hlen;



	tunnel->tun_hlen = gre_calc_hlen(tunnel->parms.o_flags);

	tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen;



	t_hlen = tunnel->hlen + sizeof(struct ipv6hdr);

	tunnel->dev->hard_header_len = LL_MAX_HEADER + t_hlen;

	return t_hlen;

}



static void ip6gre_tnl_link_config(struct ip6_tnl *t, int set_mtu)

{

	ip6gre_tnl_link_config_common(t);

	ip6gre_tnl_link_config_route(t, set_mtu, ip6gre_calc_hlen(t));

}



static void ip6gre_tnl_copy_tnl_parm(struct ip6_tnl *t,

				     const struct __ip6_tnl_parm *p)

{

	t->parms.laddr = p->laddr;

	t->parms.raddr = p->raddr;
@@ -1108,6 +1130,12 @@ static int ip6gre_tnl_change(struct ip6_tnl *t, 
	t->parms.o_flags = p->o_flags;

	t->parms.fwmark = p->fwmark;

	dst_cache_reset(&t->dst_cache);

}



static int ip6gre_tnl_change(struct ip6_tnl *t, const struct __ip6_tnl_parm *p,

			     int set_mtu)

{

	ip6gre_tnl_copy_tnl_parm(t, p);

	ip6gre_tnl_link_config(t, set_mtu);

	return 0;

}
@@ -1384,11 +1412,7 @@ static int ip6gre_tunnel_init_common(struct net_device *dev) 
		return ret;

	}



	tunnel->tun_hlen = gre_calc_hlen(tunnel->parms.o_flags);

	tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen;

	t_hlen = tunnel->hlen + sizeof(struct ipv6hdr);



	dev->hard_header_len = LL_MAX_HEADER + t_hlen;

	t_hlen = ip6gre_calc_hlen(tunnel);

	dev->mtu = ETH_DATA_LEN - t_hlen;

	if (dev->type == ARPHRD_ETHER)

		dev->mtu -= ETH_HLEN;
@@ -1731,6 +1755,19 @@ static const struct net_device_ops ip6gre_tap_netdev_ops = { 
	.ndo_get_iflink = ip6_tnl_get_iflink,

};



static int ip6erspan_calc_hlen(struct ip6_tnl *tunnel)

{

	int t_hlen;



	tunnel->tun_hlen = 8;

	tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen +

		       erspan_hdr_len(tunnel->parms.erspan_ver);



	t_hlen = tunnel->hlen + sizeof(struct ipv6hdr);

	tunnel->dev->hard_header_len = LL_MAX_HEADER + t_hlen;

	return t_hlen;

}



static int ip6erspan_tap_init(struct net_device *dev)

{

	struct ip6_tnl *tunnel;
@@ -1754,12 +1791,7 @@ static int ip6erspan_tap_init(struct net_device *dev) 
		return ret;

	}



	tunnel->tun_hlen = 8;

	tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen +

		       erspan_hdr_len(tunnel->parms.erspan_ver);

	t_hlen = tunnel->hlen + sizeof(struct ipv6hdr);



	dev->hard_header_len = LL_MAX_HEADER + t_hlen;

	t_hlen = ip6erspan_calc_hlen(tunnel);

	dev->mtu = ETH_DATA_LEN - t_hlen;

	if (dev->type == ARPHRD_ETHER)

		dev->mtu -= ETH_HLEN;
@@ -1767,7 +1799,7 @@ static int ip6erspan_tap_init(struct net_device *dev) 
		dev->mtu -= 8;



	dev->priv_flags |= IFF_LIVE_ADDR_CHANGE;

	ip6gre_tnl_link_config(tunnel, 1);

	ip6erspan_tnl_link_config(tunnel, 1);



	return 0;

}
@@ -1838,7 +1870,7 @@ static bool ip6gre_netlink_encap_parms(struct nlattr *data[], 
	return ret;

}



static int ip6gre_newlink(struct net *src_net, struct net_device *dev,

static int ip6gre_newlink_common(struct net *src_net, struct net_device *dev,

				 struct nlattr *tb[], struct nlattr *data[],

				 struct netlink_ext_ack *extack)

{
@@ -1877,49 +1909,76 @@ static int ip6gre_newlink(struct net *src_net, struct net_device *dev, 
	if (err)

		goto out;



	ip6gre_tnl_link_config(nt, !tb[IFLA_MTU]);



	if (tb[IFLA_MTU])

		ip6_tnl_change_mtu(dev, nla_get_u32(tb[IFLA_MTU]));



	dev_hold(dev);

	ip6gre_tunnel_link(ign, nt);



out:

	return err;

}



static int ip6gre_changelink(struct net_device *dev, struct nlattr *tb[],

			     struct nlattr *data[],

static int ip6gre_newlink(struct net *src_net, struct net_device *dev,

			  struct nlattr *tb[], struct nlattr *data[],

			  struct netlink_ext_ack *extack)

{

	int err = ip6gre_newlink_common(src_net, dev, tb, data, extack);

	struct ip6_tnl *nt = netdev_priv(dev);

	struct net *net = dev_net(dev);



	if (!err) {

		ip6gre_tnl_link_config(nt, !tb[IFLA_MTU]);

		ip6gre_tunnel_link(net_generic(net, ip6gre_net_id), nt);

	}

	return err;

}



static struct ip6_tnl *

ip6gre_changelink_common(struct net_device *dev, struct nlattr *tb[],

			 struct nlattr *data[], struct __ip6_tnl_parm *p_p,

			 struct netlink_ext_ack *extack)

{

	struct ip6_tnl *t, *nt = netdev_priv(dev);

	struct net *net = nt->net;

	struct ip6gre_net *ign = net_generic(net, ip6gre_net_id);

	struct __ip6_tnl_parm p;

	struct ip_tunnel_encap ipencap;



	if (dev == ign->fb_tunnel_dev)

		return -EINVAL;

		return ERR_PTR(-EINVAL);



	if (ip6gre_netlink_encap_parms(data, &ipencap)) {

		int err = ip6_tnl_encap_setup(nt, &ipencap);



		if (err < 0)

			return err;

			return ERR_PTR(err);

	}



	ip6gre_netlink_parms(data, &p);

	ip6gre_netlink_parms(data, p_p);



	t = ip6gre_tunnel_locate(net, &p, 0);

	t = ip6gre_tunnel_locate(net, p_p, 0);



	if (t) {

		if (t->dev != dev)

			return -EEXIST;

			return ERR_PTR(-EEXIST);

	} else {

		t = nt;

	}



	return t;

}



static int ip6gre_changelink(struct net_device *dev, struct nlattr *tb[],

			     struct nlattr *data[],

			     struct netlink_ext_ack *extack)

{

	struct ip6gre_net *ign = net_generic(dev_net(dev), ip6gre_net_id);

	struct __ip6_tnl_parm p;

	struct ip6_tnl *t;



	t = ip6gre_changelink_common(dev, tb, data, &p, extack);

	if (IS_ERR(t))

		return PTR_ERR(t);



	ip6gre_tunnel_unlink(ign, t);

	ip6gre_tnl_change(t, &p, !tb[IFLA_MTU]);

	ip6gre_tunnel_link(ign, t);
@@ -2071,6 +2130,53 @@ static void ip6erspan_tap_setup(struct net_device *dev) 
	netif_keep_dst(dev);

}



static int ip6erspan_newlink(struct net *src_net, struct net_device *dev,

			     struct nlattr *tb[], struct nlattr *data[],

			     struct netlink_ext_ack *extack)

{

	int err = ip6gre_newlink_common(src_net, dev, tb, data, extack);

	struct ip6_tnl *nt = netdev_priv(dev);

	struct net *net = dev_net(dev);



	if (!err) {

		ip6erspan_tnl_link_config(nt, !tb[IFLA_MTU]);

		ip6gre_tunnel_link(net_generic(net, ip6gre_net_id), nt);

	}

	return err;

}



static void ip6erspan_tnl_link_config(struct ip6_tnl *t, int set_mtu)

{

	ip6gre_tnl_link_config_common(t);

	ip6gre_tnl_link_config_route(t, set_mtu, ip6erspan_calc_hlen(t));

}



static int ip6erspan_tnl_change(struct ip6_tnl *t,

				const struct __ip6_tnl_parm *p, int set_mtu)

{

	ip6gre_tnl_copy_tnl_parm(t, p);

	ip6erspan_tnl_link_config(t, set_mtu);

	return 0;

}



static int ip6erspan_changelink(struct net_device *dev, struct nlattr *tb[],

				struct nlattr *data[],

				struct netlink_ext_ack *extack)

{

	struct ip6gre_net *ign = net_generic(dev_net(dev), ip6gre_net_id);

	struct __ip6_tnl_parm p;

	struct ip6_tnl *t;



	t = ip6gre_changelink_common(dev, tb, data, &p, extack);

	if (IS_ERR(t))

		return PTR_ERR(t);



	ip6gre_tunnel_unlink(ign, t);

	ip6erspan_tnl_change(t, &p, !tb[IFLA_MTU]);

	ip6gre_tunnel_link(ign, t);

	return 0;

}



static struct rtnl_link_ops ip6gre_link_ops __read_mostly = {

	.kind		= "ip6gre",

	.maxtype	= IFLA_GRE_MAX,
@@ -2107,8 +2213,8 @@ static struct rtnl_link_ops ip6erspan_tap_ops __read_mostly = { 
	.priv_size	= sizeof(struct ip6_tnl),

	.setup		= ip6erspan_tap_setup,

	.validate	= ip6erspan_tap_validate,

	.newlink	= ip6gre_newlink,

	.changelink	= ip6gre_changelink,

	.newlink	= ip6erspan_newlink,

	.changelink	= ip6erspan_changelink,

	.get_size	= ip6gre_get_size,

	.fill_info	= ip6gre_fill_info,

	.get_link_net	= ip6_tnl_get_link_net,

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