[PATCH 3.10 25/58] netfilter: push reasm skb through instead of original frag skbs

Greg Kroah-Hartman
2013-12-06T22:15:07Z

From: Jiri Pirko <jiri@resnulli.us>

[ Upstream commit 6aafeef03b9d9ecf255f3a80ed85ee070260e1ae ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/skbuff.h | 32 --------------
include/net/ip_vs.h | 32 --------------
include/net/netfilter/ipv6/nf_defrag_ipv6.h | 5 --
net/core/skbuff.c | 3 -
net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c | 54 ------------------------
net/ipv6/netfilter/nf_conntrack_reasm.c | 19 --------
net/ipv6/netfilter/nf_defrag_ipv6_hooks.c | 7 ++-
net/netfilter/ipvs/ip_vs_core.c | 55 -------------------------
net/netfilter/ipvs/ip_vs_pe_sip.c | 8 ---
9 files changed, 13 insertions(+), 202 deletions(-)

--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -331,11 +331,6 @@ typedef unsigned int sk_buff_data_t;
typedef unsigned char *sk_buff_data_t;
#endif

-#if defined(CONFIG_NF_DEFRAG_IPV4) || defined(CONFIG_NF_DEFRAG_IPV4_MODULE) || \
- defined(CONFIG_NF_DEFRAG_IPV6) || defined(CONFIG_NF_DEFRAG_IPV6_MODULE)
-#define NET_SKBUFF_NF_DEFRAG_NEEDED 1
-#endif
-
/**
* struct sk_buff - socket buffer
* @next: Next buffer in list
@@ -368,7 +363,6 @@ typedef unsigned char *sk_buff_data_t;
* @protocol: Packet protocol from driver
* @destructor: Destruct function
* @nfct: Associated connection, if any
- * @nfct_reasm: netfilter conntrack re-assembly pointer
* @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
* @skb_iif: ifindex of device we arrived on
* @tc_index: Traffic control index
@@ -455,9 +449,6 @@ struct sk_buff {
#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
struct nf_conntrack *nfct;
#endif
-#ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
- struct sk_buff *nfct_reasm;
-#endif
#ifdef CONFIG_BRIDGE_NETFILTER
struct nf_bridge_info *nf_bridge;
#endif
@@ -2700,18 +2691,6 @@ static inline void nf_conntrack_get(stru
atomic_inc(&nfct->use);
}
#endif
-#ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
-static inline void nf_conntrack_get_reasm(struct sk_buff *skb)
-{
- if (skb)
- atomic_inc(&skb->users);
-}
-static inline void nf_conntrack_put_reasm(struct sk_buff *skb)
-{
- if (skb)
- kfree_skb(skb);
-}
-#endif
#ifdef CONFIG_BRIDGE_NETFILTER
static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
{
@@ -2730,10 +2709,6 @@ static inline void nf_reset(struct sk_bu
nf_conntrack_put(skb->nfct);
skb->nfct = NULL;
#endif
-#ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
- nf_conntrack_put_reasm(skb->nfct_reasm);
- skb->nfct_reasm = NULL;
-#endif
#ifdef CONFIG_BRIDGE_NETFILTER
nf_bridge_put(skb->nf_bridge);
skb->nf_bridge = NULL;
@@ -2755,10 +2730,6 @@ static inline void __nf_copy(struct sk_b
nf_conntrack_get(src->nfct);
dst->nfctinfo = src->nfctinfo;
#endif
-#ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
- dst->nfct_reasm = src->nfct_reasm;
- nf_conntrack_get_reasm(src->nfct_reasm);
-#endif
#ifdef CONFIG_BRIDGE_NETFILTER
dst->nf_bridge = src->nf_bridge;
nf_bridge_get(src->nf_bridge);
@@ -2770,9 +2741,6 @@ static inline void nf_copy(struct sk_buf
#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
nf_conntrack_put(dst->nfct);
#endif
-#ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
- nf_conntrack_put_reasm(dst->nfct_reasm);
-#endif
#ifdef CONFIG_BRIDGE_NETFILTER
nf_bridge_put(dst->nf_bridge);
#endif
--- a/include/net/ip_vs.h
+++ b/include/net/ip_vs.h
@@ -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
(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
{
--- a/include/net/netfilter/ipv6/nf_defrag_ipv6.h
+++ b/include/net/netfilter/ipv6/nf_defrag_ipv6.h
@@ -6,10 +6,7 @@ extern void nf_defrag_ipv6_enable(void);
extern int nf_ct_frag6_init(void);
extern void nf_ct_frag6_cleanup(void);
extern struct sk_buff *nf_ct_frag6_gather(struct sk_buff *skb, u32 user);
-extern 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 *));
+extern void nf_ct_frag6_consume_orig(struct sk_buff *skb);

struct inet_frags_ctl;

--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -585,9 +585,6 @@ static void skb_release_head_state(struc
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
nf_conntrack_put(skb->nfct);
#endif
-#ifdef NET_SKBUFF_NF_DEFRAG_NEEDED
- nf_conntrack_put_reasm(skb->nfct_reasm);
-#endif
#ifdef CONFIG_BRIDGE_NETFILTER
nf_bridge_put(skb->nf_bridge);
#endif
--- a/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
+++ b/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
@@ -172,63 +172,13 @@ out:
return nf_conntrack_confirm(skb);
}

-static unsigned int __ipv6_conntrack_in(struct net *net,
- unsigned int hooknum,
- struct sk_buff *skb,
- const struct net_device *in,
- const struct net_device *out,
- int (*okfn)(struct sk_buff *))
-{
- struct sk_buff *reasm = skb->nfct_reasm;
- const struct nf_conn_help *help;
- struct nf_conn *ct;
- enum ip_conntrack_info ctinfo;
-
- /* This packet is fragmented and has reassembled packet. */
- if (reasm) {
- /* Reassembled packet isn't parsed yet ? */
- if (!reasm->nfct) {
- unsigned int ret;
-
- ret = nf_conntrack_in(net, PF_INET6, hooknum, reasm);
- if (ret != NF_ACCEPT)
- return ret;
- }
-
- /* Conntrack helpers need the entire reassembled packet in the
- * POST_ROUTING hook. In case of unconfirmed connections NAT
- * might reassign a helper, so the entire packet is also
- * required.
- */
- ct = nf_ct_get(reasm, &ctinfo);
- if (ct != NULL && !nf_ct_is_untracked(ct)) {
- help = nfct_help(ct);
- if ((help && help->helper) || !nf_ct_is_confirmed(ct)) {
- nf_conntrack_get_reasm(reasm);
- NF_HOOK_THRESH(NFPROTO_IPV6, hooknum, reasm,
- (struct net_device *)in,
- (struct net_device *)out,
- okfn, NF_IP6_PRI_CONNTRACK + 1);
- return NF_DROP_ERR(-ECANCELED);
- }
- }
-
- nf_conntrack_get(reasm->nfct);
- skb->nfct = reasm->nfct;
- skb->nfctinfo = reasm->nfctinfo;
- return NF_ACCEPT;
- }
-
- return nf_conntrack_in(net, PF_INET6, hooknum, skb);
-}
-
static unsigned int ipv6_conntrack_in(unsigned int hooknum,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
- return __ipv6_conntrack_in(dev_net(in), hooknum, skb, in, out, okfn);
+ return nf_conntrack_in(dev_net(in), PF_INET6, hooknum, skb);
}

static unsigned int ipv6_conntrack_local(unsigned int hooknum,
@@ -242,7 +192,7 @@ static unsigned int ipv6_conntrack_local
net_notice_ratelimited("ipv6_conntrack_local: packet too short\n");
return NF_ACCEPT;
}
- return __ipv6_conntrack_in(dev_net(out), hooknum, skb, in, out, okfn);
+ return nf_conntrack_in(dev_net(out), PF_INET6, hooknum, skb);
}

static struct nf_hook_ops ipv6_conntrack_ops[] __read_mostly = {
--- a/net/ipv6/netfilter/nf_conntrack_reasm.c
+++ b/net/ipv6/netfilter/nf_conntrack_reasm.c
@@ -621,31 +621,16 @@ ret_orig:
return skb;
}

-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 sk_buff *s, *s2;
- unsigned int ret = 0;

for (s = NFCT_FRAG6_CB(skb)->orig; s;) {
- nf_conntrack_put_reasm(s->nfct_reasm);
- nf_conntrack_get_reasm(skb);
- s->nfct_reasm = skb;
-
s2 = s->next;
s->next = NULL;
-
- if (ret != -ECANCELED)
- ret = NF_HOOK_THRESH(NFPROTO_IPV6, hooknum, s,
- in, out, okfn,
- NF_IP6_PRI_CONNTRACK_DEFRAG + 1);
- else
- kfree_skb(s);
-
+ consume_skb(s);
s = s2;
}
- nf_conntrack_put_reasm(skb);
}

static int nf_ct_net_init(struct net *net)
--- a/net/ipv6/netfilter/nf_defrag_ipv6_hooks.c
+++ b/net/ipv6/netfilter/nf_defrag_ipv6_hooks.c
@@ -75,8 +75,11 @@ static unsigned int ipv6_defrag(unsigned
if (reasm == skb)
return NF_ACCEPT;

- nf_ct_frag6_output(hooknum, reasm, (struct net_device *)in,
- (struct net_device *)out, okfn);
+ nf_ct_frag6_consume_orig(reasm);
+
+ NF_HOOK_THRESH(NFPROTO_IPV6, hooknum, reasm,
+ (struct net_device *) in, (struct net_device *) out,
+ okfn, NF_IP6_PRI_CONNTRACK_DEFRAG + 1);

return NF_STOLEN;
}
--- a/net/netfilter/ipvs/ip_vs_core.c
+++ b/net/netfilter/ipvs/ip_vs_core.c
@@ -1131,12 +1131,6 @@ ip_vs_out(unsigned int hooknum, struct s
ip_vs_fill_iph_skb(af, skb, &iph);
#ifdef CONFIG_IP_VS_IPV6
if (af == AF_INET6) {
- if (!iph.fragoffs && skb_nfct_reasm(skb)) {
- struct sk_buff *reasm = skb_nfct_reasm(skb);
- /* Save fw mark for coming frags */
- reasm->ipvs_property = 1;
- reasm->mark = skb->mark;
- }
if (unlikely(iph.protocol == IPPROTO_ICMPV6)) {
int related;
int verdict = ip_vs_out_icmp_v6(skb, &related,
@@ -1606,12 +1600,6 @@ ip_vs_in(unsigned int hooknum, struct sk

#ifdef CONFIG_IP_VS_IPV6
if (af == AF_INET6) {
- if (!iph.fragoffs && skb_nfct_reasm(skb)) {
- struct sk_buff *reasm = skb_nfct_reasm(skb);
- /* Save fw mark for coming frags. */
- reasm->ipvs_property = 1;
- reasm->mark = skb->mark;
- }
if (unlikely(iph.protocol == IPPROTO_ICMPV6)) {
int related;
int verdict = ip_vs_in_icmp_v6(skb, &related, hooknum,
@@ -1663,9 +1651,8 @@ ip_vs_in(unsigned int hooknum, struct sk
/* sorry, all this trouble for a no-hit :) */
IP_VS_DBG_PKT(12, af, pp, skb, 0,
"ip_vs_in: packet continues traversal as normal");
- if (iph.fragoffs && !skb_nfct_reasm(skb)) {
+ if (iph.fragoffs) {
/* Fragment that couldn't be mapped to a conn entry
- * and don't have any pointer to a reasm skb
* is missing module nf_defrag_ipv6
*/
IP_VS_DBG_RL("Unhandled frag, load nf_defrag_ipv6\n");
@@ -1748,38 +1735,6 @@ ip_vs_local_request4(unsigned int hooknu
#ifdef CONFIG_IP_VS_IPV6

/*
- * AF_INET6 fragment handling
- * Copy info from first fragment, to the rest of them.
- */
-static unsigned int
-ip_vs_preroute_frag6(unsigned int hooknum, struct sk_buff *skb,
- const struct net_device *in,
- const struct net_device *out,
- int (*okfn)(struct sk_buff *))
-{
- struct sk_buff *reasm = skb_nfct_reasm(skb);
- struct net *net;
-
- /* Skip if not a "replay" from nf_ct_frag6_output or first fragment.
- * ipvs_property is set when checking first fragment
- * in ip_vs_in() and ip_vs_out().
- */
- if (reasm)
- IP_VS_DBG(2, "Fragment recv prop:%d\n", reasm->ipvs_property);
- if (!reasm || !reasm->ipvs_property)
- return NF_ACCEPT;
-
- net = skb_net(skb);
- if (!net_ipvs(net)->enable)
- return NF_ACCEPT;
-
- /* Copy stored fw mark, saved in ip_vs_{in,out} */
- skb->mark = reasm->mark;
-
- return NF_ACCEPT;
-}
-
-/*
* AF_INET6 handler in NF_INET_LOCAL_IN chain
* Schedule and forward packets from remote clients
*/
@@ -1916,14 +1871,6 @@ static struct nf_hook_ops ip_vs_ops[] __
.priority = 100,
},
#ifdef CONFIG_IP_VS_IPV6
- /* After mangle & nat fetch 2:nd fragment and following */
- {
- .hook = ip_vs_preroute_frag6,
- .owner = THIS_MODULE,
- .pf = NFPROTO_IPV6,
- .hooknum = NF_INET_PRE_ROUTING,
- .priority = NF_IP6_PRI_NAT_DST + 1,
- },
/* After packet filtering, change source only for VS/NAT */
{
.hook = ip_vs_reply6,
--- a/net/netfilter/ipvs/ip_vs_pe_sip.c
+++ b/net/netfilter/ipvs/ip_vs_pe_sip.c
@@ -65,7 +65,6 @@ static int get_callid(const char *dptr,
static int
ip_vs_sip_fill_param(struct ip_vs_conn_param *p, struct sk_buff *skb)
{
- struct sk_buff *reasm = skb_nfct_reasm(skb);
struct ip_vs_iphdr iph;
unsigned int dataoff, datalen, matchoff, matchlen;
const char *dptr;
@@ -79,15 +78,10 @@ ip_vs_sip_fill_param(struct ip_vs_conn_p
/* todo: IPv6 fragments:
* I think this only should be done for the first fragment. /HS
*/
- if (reasm) {
- skb = reasm;
- dataoff = iph.thoff_reasm + sizeof(struct udphdr);
- } else
- dataoff = iph.len + sizeof(struct udphdr);
+ dataoff = iph.len + sizeof(struct udphdr);

if (dataoff >= skb->len)
return -EINVAL;
- /* todo: Check if this will mess-up the reasm skb !!! /HS */
retc = skb_linearize(skb);
if (retc < 0)
return retc;