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Revision 78c906e430b13d30a8cfbdef4ccbbe1686841a9e authored by Vlad Buslov on 31 August 2020, 13:17:29 UTC, committed by Saeed Mahameed on 05 November 2020, 20:17:05 UTC 
net/mlx5e: Protect encap route dev from concurrent release
 
In functions mlx5e_route_lookup_ipv{4|6}() route_dev can be arbitrary net
device and not necessary mlx5 eswitch port representor. As such, in order
to ensure that route_dev is not destroyed concurrent the code needs either
explicitly take reference to the device before releasing reference to
rtable instance or ensure that caller holds rtnl lock. First approach is
chosen as a fix since rtnl lock dependency was intentionally removed from
mlx5 TC layer.

To prevent unprotected usage of route_dev in encap code take a reference to
the device before releasing rt. Don't save direct pointer to the device in
mlx5_encap_entry structure and use ifindex instead. Modify users of
route_dev pointer to properly obtain the net device instance from its
ifindex.

Fixes: 61086f391044 ("net/mlx5e: Protect encap hash table with mutex")
Fixes: 6707f74be862 ("net/mlx5e: Update hw flows when encap source mac changed")
Signed-off-by: Vlad Buslov <vladbu@nvidia.com>
Reviewed-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
1 parent e68e28b
Raw File
netfilter.c 
/*
 * IPv4 specific functions of netfilter core
 *
 * Rusty Russell (C) 2000 -- This code is GPL.
 * Patrick McHardy (C) 2006-2012
 */
#include <linux/kernel.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <linux/ip.h>
#include <linux/skbuff.h>
#include <linux/gfp.h>
#include <linux/export.h>
#include <net/route.h>
#include <net/xfrm.h>
#include <net/ip.h>
#include <net/netfilter/nf_queue.h>

/* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
int ip_route_me_harder(struct net *net, struct sock *sk, struct sk_buff *skb, unsigned int addr_type)
{
	const struct iphdr *iph = ip_hdr(skb);
	struct rtable *rt;
	struct flowi4 fl4 = {};
	__be32 saddr = iph->saddr;
	__u8 flags;
	struct net_device *dev = skb_dst(skb)->dev;
	unsigned int hh_len;

	sk = sk_to_full_sk(sk);
	flags = sk ? inet_sk_flowi_flags(sk) : 0;

	if (addr_type == RTN_UNSPEC)
		addr_type = inet_addr_type_dev_table(net, dev, saddr);
	if (addr_type == RTN_LOCAL || addr_type == RTN_UNICAST)
		flags |= FLOWI_FLAG_ANYSRC;
	else
		saddr = 0;

	/* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
	 * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook.
	 */
	fl4.daddr = iph->daddr;
	fl4.saddr = saddr;
	fl4.flowi4_tos = RT_TOS(iph->tos);
	fl4.flowi4_oif = sk ? sk->sk_bound_dev_if : 0;
	if (!fl4.flowi4_oif)
		fl4.flowi4_oif = l3mdev_master_ifindex(dev);
	fl4.flowi4_mark = skb->mark;
	fl4.flowi4_flags = flags;
	rt = ip_route_output_key(net, &fl4);
	if (IS_ERR(rt))
		return PTR_ERR(rt);

	/* Drop old route. */
	skb_dst_drop(skb);
	skb_dst_set(skb, &rt->dst);

	if (skb_dst(skb)->error)
		return skb_dst(skb)->error;

#ifdef CONFIG_XFRM
	if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
	    xfrm_decode_session(skb, flowi4_to_flowi(&fl4), AF_INET) == 0) {
		struct dst_entry *dst = skb_dst(skb);
		skb_dst_set(skb, NULL);
		dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), sk, 0);
		if (IS_ERR(dst))
			return PTR_ERR(dst);
		skb_dst_set(skb, dst);
	}
#endif

	/* Change in oif may mean change in hh_len. */
	hh_len = skb_dst(skb)->dev->hard_header_len;
	if (skb_headroom(skb) < hh_len &&
	    pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),
				0, GFP_ATOMIC))
		return -ENOMEM;

	return 0;
}
EXPORT_SYMBOL(ip_route_me_harder);

int nf_ip_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
		bool strict __always_unused)
{
	struct rtable *rt = ip_route_output_key(net, &fl->u.ip4);
	if (IS_ERR(rt))
		return PTR_ERR(rt);
	*dst = &rt->dst;
	return 0;
}
EXPORT_SYMBOL_GPL(nf_ip_route);
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