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netfilter: push reasm skb through instead of original frag skbs

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Pushing original fragments through causes several problems. For example
for matching, frags may not be matched correctly. Take following
example:

<example>
On HOSTA do:
ip6tables -I INPUT -p icmpv6 -j DROP
ip6tables -I INPUT -p icmpv6 -m icmp6 --icmpv6-type 128 -j ACCEPT

and on HOSTB you do:
ping6 HOSTA -s2000    (MTU is 1500)

Incoming echo requests will be filtered out on HOSTA. This issue does
not occur with smaller packets than MTU (where fragmentation does not happen)
</example>

As was discussed previously, the only correct solution seems to be to use
reassembled skb instead of separete frags. Doing this has positive side
effects in reducing sk_buff by one pointer (nfct_reasm) and also the reams
dances in ipvs and conntrack can be removed.

Future plan is to remove net/ipv6/netfilter/nf_conntrack_reasm.c
entirely and use code in net/ipv6/reassembly.c instead.

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Marcelo Ricardo Leitner <mleitner@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jiri Pirko
2013-11-06 17:52:20 +01:00
committed by David S. Miller
parent 9037c3579a
commit 6aafeef03b
9 changed files with 13 additions and 203 deletions
Download Patch File Download Diff File Expand all files Collapse all files

32
include/net/ip_vs.h
View File

@@ -109,7 +109,6 @@ extern int ip_vs_conn_tab_size;
struct ip_vs_iphdr {
__u32 len; /* IPv4 simply where L4 starts
IPv6 where L4 Transport Header starts */
__u32 thoff_reasm; /* Transport Header Offset in nfct_reasm skb */
__u16 fragoffs; /* IPv6 fragment offset, 0 if first frag (or not frag)*/
__s16 protocol;
__s32 flags;
@@ -117,34 +116,12 @@ struct ip_vs_iphdr {
union nf_inet_addr daddr;
};
/* Dependency to module: nf_defrag_ipv6 */
#if defined(CONFIG_NF_DEFRAG_IPV6) || defined(CONFIG_NF_DEFRAG_IPV6_MODULE)
static inline struct sk_buff *skb_nfct_reasm(const struct sk_buff *skb)
{
return skb->nfct_reasm;
}
static inline void *frag_safe_skb_hp(const struct sk_buff *skb, int offset,
int len, void *buffer,
const struct ip_vs_iphdr *ipvsh)
{
if (unlikely(ipvsh->fragoffs && skb_nfct_reasm(skb)))
return skb_header_pointer(skb_nfct_reasm(skb),
ipvsh->thoff_reasm, len, buffer);
return skb_header_pointer(skb, offset, len, buffer);
}
#else
static inline struct sk_buff *skb_nfct_reasm(const struct sk_buff *skb)
{
return NULL;
}
static inline void *frag_safe_skb_hp(const struct sk_buff *skb, int offset,
int len, void *buffer,
const struct ip_vs_iphdr *ipvsh)
{
return skb_header_pointer(skb, offset, len, buffer);
}
#endif
static inline void
ip_vs_fill_ip4hdr(const void *nh, struct ip_vs_iphdr *iphdr)
@@ -171,19 +148,12 @@ ip_vs_fill_iph_skb(int af, const struct sk_buff *skb, struct ip_vs_iphdr *iphdr)
(struct ipv6hdr *)skb_network_header(skb);
iphdr->saddr.in6 = iph->saddr;
iphdr->daddr.in6 = iph->daddr;
/* ipv6_find_hdr() updates len, flags, thoff_reasm */
iphdr->thoff_reasm = 0;
/* ipv6_find_hdr() updates len, flags */
iphdr->len = 0;
iphdr->flags = 0;
iphdr->protocol = ipv6_find_hdr(skb, &iphdr->len, -1,
&iphdr->fragoffs,
&iphdr->flags);
/* get proto from re-assembled packet and it's offset */
if (skb_nfct_reasm(skb))
iphdr->protocol = ipv6_find_hdr(skb_nfct_reasm(skb),
&iphdr->thoff_reasm,
-1, NULL, NULL);
} else
#endif
{

4
include/net/netfilter/ipv6/nf_defrag_ipv6.h
View File

@@ -6,9 +6,7 @@ void nf_defrag_ipv6_enable(void);
int nf_ct_frag6_init(void);
void nf_ct_frag6_cleanup(void);
struct sk_buff *nf_ct_frag6_gather(struct sk_buff *skb, u32 user);
void nf_ct_frag6_output(unsigned int hooknum, struct sk_buff *skb,
struct net_device *in, struct net_device *out,
int (*okfn)(struct sk_buff *));
void nf_ct_frag6_consume_orig(struct sk_buff *skb);
struct inet_frags_ctl;