linux/net/ipv4/netfilter.c
David Ahern 6d8b49c3a3 netfilter: Update ip_route_me_harder to consider L3 domain
ip_route_me_harder is not considering the L3 domain and sending lookups
to the wrong table. For example consider the following output rule:

iptables -I OUTPUT -p tcp --dport 12345 -j REJECT --reject-with tcp-reset

using perf to analyze lookups via the fib_table_lookup tracepoint shows:

vrf-test  1187 [001] 46887.295927: fib:fib_table_lookup: table 255 oif 0 iif 0 src 0.0.0.0 dst 10.100.1.254 tos 0 scope 0 flags 0
        ffffffff8143922c perf_trace_fib_table_lookup ([kernel.kallsyms])
        ffffffff81493aac fib_table_lookup ([kernel.kallsyms])
        ffffffff8148dda3 __inet_dev_addr_type ([kernel.kallsyms])
        ffffffff8148ddf6 inet_addr_type ([kernel.kallsyms])
        ffffffff8149e344 ip_route_me_harder ([kernel.kallsyms])

and

vrf-test  1187 [001] 46887.295933: fib:fib_table_lookup: table 255 oif 0 iif 1 src 10.100.1.254 dst 10.100.1.2 tos 0 scope 0 flags
        ffffffff8143922c perf_trace_fib_table_lookup ([kernel.kallsyms])
        ffffffff81493aac fib_table_lookup ([kernel.kallsyms])
        ffffffff814998ff fib4_rule_action ([kernel.kallsyms])
        ffffffff81437f35 fib_rules_lookup ([kernel.kallsyms])
        ffffffff81499758 __fib_lookup ([kernel.kallsyms])
        ffffffff8144f010 fib_lookup.constprop.34 ([kernel.kallsyms])
        ffffffff8144f759 __ip_route_output_key_hash ([kernel.kallsyms])
        ffffffff8144fc6a ip_route_output_flow ([kernel.kallsyms])
        ffffffff8149e39b ip_route_me_harder ([kernel.kallsyms])

In both cases the lookups are directed to table 255 rather than the
table associated with the device via the L3 domain. Update both
lookups to pull the L3 domain from the dst currently attached to the
skb.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2016-11-24 12:44:36 +01:00

203 lines
5.3 KiB
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 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 = skb->sk ? inet_sk_flowi_flags(skb->sk) : 0;
struct net_device *dev = skb_dst(skb)->dev;
unsigned int hh_len;
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 = skb->sk ? skb->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), skb->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);
/*
* Extra routing may needed on local out, as the QUEUE target never
* returns control to the table.
*/
struct ip_rt_info {
__be32 daddr;
__be32 saddr;
u_int8_t tos;
u_int32_t mark;
};
static void nf_ip_saveroute(const struct sk_buff *skb,
struct nf_queue_entry *entry)
{
struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
if (entry->state.hook == NF_INET_LOCAL_OUT) {
const struct iphdr *iph = ip_hdr(skb);
rt_info->tos = iph->tos;
rt_info->daddr = iph->daddr;
rt_info->saddr = iph->saddr;
rt_info->mark = skb->mark;
}
}
static int nf_ip_reroute(struct net *net, struct sk_buff *skb,
const struct nf_queue_entry *entry)
{
const struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
if (entry->state.hook == NF_INET_LOCAL_OUT) {
const struct iphdr *iph = ip_hdr(skb);
if (!(iph->tos == rt_info->tos &&
skb->mark == rt_info->mark &&
iph->daddr == rt_info->daddr &&
iph->saddr == rt_info->saddr))
return ip_route_me_harder(net, skb, RTN_UNSPEC);
}
return 0;
}
__sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
unsigned int dataoff, u_int8_t protocol)
{
const struct iphdr *iph = ip_hdr(skb);
__sum16 csum = 0;
switch (skb->ip_summed) {
case CHECKSUM_COMPLETE:
if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
break;
if ((protocol == 0 && !csum_fold(skb->csum)) ||
!csum_tcpudp_magic(iph->saddr, iph->daddr,
skb->len - dataoff, protocol,
skb->csum)) {
skb->ip_summed = CHECKSUM_UNNECESSARY;
break;
}
/* fall through */
case CHECKSUM_NONE:
if (protocol == 0)
skb->csum = 0;
else
skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
skb->len - dataoff,
protocol, 0);
csum = __skb_checksum_complete(skb);
}
return csum;
}
EXPORT_SYMBOL(nf_ip_checksum);
static __sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook,
unsigned int dataoff, unsigned int len,
u_int8_t protocol)
{
const struct iphdr *iph = ip_hdr(skb);
__sum16 csum = 0;
switch (skb->ip_summed) {
case CHECKSUM_COMPLETE:
if (len == skb->len - dataoff)
return nf_ip_checksum(skb, hook, dataoff, protocol);
/* fall through */
case CHECKSUM_NONE:
skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, protocol,
skb->len - dataoff, 0);
skb->ip_summed = CHECKSUM_NONE;
return __skb_checksum_complete_head(skb, dataoff + len);
}
return csum;
}
static 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;
}
static const struct nf_afinfo nf_ip_afinfo = {
.family = AF_INET,
.checksum = nf_ip_checksum,
.checksum_partial = nf_ip_checksum_partial,
.route = nf_ip_route,
.saveroute = nf_ip_saveroute,
.reroute = nf_ip_reroute,
.route_key_size = sizeof(struct ip_rt_info),
};
static int __init ipv4_netfilter_init(void)
{
return nf_register_afinfo(&nf_ip_afinfo);
}
subsys_initcall(ipv4_netfilter_init);