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ipvs: Complete IPv6 fragment handling for IPVS

Browse source 
IPVS now supports fragmented packets, with support from nf_conntrack_reasm.c

Based on patch from: Hans Schillstrom.

IPVS do like conntrack i.e. use the skb->nfct_reasm
(i.e. when all fragments is collected, nf_ct_frag6_output()
starts a "re-play" of all fragments into the interrupted
PREROUTING chain at prio -399 (NF_IP6_PRI_CONNTRACK_DEFRAG+1)
with nfct_reasm pointing to the assembled packet.)

Notice, module nf_defrag_ipv6 must be loaded for this to work.
Report unhandled fragments, and recommend user to load nf_defrag_ipv6.

To handle fw-mark for fragments.  Add a new IPVS hook into prerouting
chain at prio -99 (NF_IP6_PRI_NAT_DST+1) to catch fragments, and copy
fw-mark info from the first packet with an upper layer header.

IPv6 fragment handling should be the last thing on the IPVS IPv6
missing support list.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Hans Schillstrom <hans@schillstrom.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
This commit is contained in:
Jesper Dangaard Brouer 2012-09-26 14:06:59 +02:00 committed by Simon Horman
parent 63dca2c0b0
commit 2f74713d14
5 changed files with 164 additions and 36 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

39
include/net/ip_vs.h
View file

@ -109,6 +109,7 @@ 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;
@ -116,6 +117,35 @@ 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)
{
@ -141,12 +171,19 @@ 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 */
/* ipv6_find_hdr() updates len, flags, thoff_reasm */
iphdr->thoff_reasm = 0;
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
{

6
net/netfilter/ipvs/Kconfig
View file

@ -30,11 +30,9 @@ config IP_VS_IPV6
depends on IPV6 = y || IP_VS = IPV6
select IP6_NF_IPTABLES
---help---
Add IPv6 support to IPVS. This is incomplete and might be dangerous.
Add IPv6 support to IPVS.
See http://www.mindbasket.com/ipvs for more information.
Say N if unsure.
Say Y if unsure.
config IP_VS_DEBUG
bool "IP virtual server debugging"

2
net/netfilter/ipvs/ip_vs_conn.c
View file

@ -314,7 +314,7 @@ ip_vs_conn_fill_param_proto(int af, const struct sk_buff *skb,
__be16 _ports[2], *pptr;
struct net *net = skb_net(skb);
pptr = skb_header_pointer(skb, proto_off, sizeof(_ports), _ports);
pptr = frag_safe_skb_hp(skb, proto_off, sizeof(_ports), _ports, iph);
if (pptr == NULL)
return 1;

117
net/netfilter/ipvs/ip_vs_core.c
View file

@ -402,8 +402,12 @@ ip_vs_schedule(struct ip_vs_service *svc, struct sk_buff *skb,
unsigned int flags;
*ignored = 1;
/*
* IPv6 frags, only the first hit here.
*/
ip_vs_fill_iph_skb(svc->af, skb, &iph);
pptr = skb_header_pointer(skb, iph.len, sizeof(_ports), _ports);
pptr = frag_safe_skb_hp(skb, iph.len, sizeof(_ports), _ports, &iph);
if (pptr == NULL)
return NULL;
@ -507,8 +511,7 @@ int ip_vs_leave(struct ip_vs_service *svc, struct sk_buff *skb,
#endif
ip_vs_fill_iph_skb(svc->af, skb, &iph);
pptr = skb_header_pointer(skb, iph.len, sizeof(_ports), _ports);
pptr = frag_safe_skb_hp(skb, iph.len, sizeof(_ports), _ports, &iph);
if (pptr == NULL) {
ip_vs_service_put(svc);
return NF_DROP;
@ -654,14 +657,6 @@ static inline int ip_vs_gather_frags(struct sk_buff *skb, u_int32_t user)
return err;
}
#ifdef CONFIG_IP_VS_IPV6
static inline int ip_vs_gather_frags_v6(struct sk_buff *skb, u_int32_t user)
{
/* TODO IPv6: Find out what to do here for IPv6 */
return 0;
}
#endif
static int ip_vs_route_me_harder(int af, struct sk_buff *skb)
{
#ifdef CONFIG_IP_VS_IPV6
@ -939,8 +934,7 @@ static int ip_vs_out_icmp_v6(struct sk_buff *skb, int *related,
ip_vs_fill_iph_skb(AF_INET6, skb, ipvsh);
*related = 1;
ic = skb_header_pointer(skb, ipvsh->len, sizeof(_icmph), &_icmph);
ic = frag_safe_skb_hp(skb, ipvsh->len, sizeof(_icmph), &_icmph, ipvsh);
if (ic == NULL)
return NF_DROP;
@ -955,6 +949,11 @@ static int ip_vs_out_icmp_v6(struct sk_buff *skb, int *related,
*related = 0;
return NF_ACCEPT;
}
/* Fragment header that is before ICMP header tells us that:
* it's not an error message since they can't be fragmented.
*/
if (ipvsh->flags & IP6T_FH_F_FRAG)
return NF_DROP;
IP_VS_DBG(8, "Outgoing ICMPv6 (%d,%d) %pI6c->%pI6c\n",
ic->icmp6_type, ntohs(icmpv6_id(ic)),
@ -1117,6 +1116,12 @@ ip_vs_out(unsigned int hooknum, struct sk_buff *skb, int af)
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,
@ -1124,7 +1129,6 @@ ip_vs_out(unsigned int hooknum, struct sk_buff *skb, int af)
if (related)
return verdict;
ip_vs_fill_iph_skb(af, skb, &iph);
}
} else
#endif
@ -1134,7 +1138,6 @@ ip_vs_out(unsigned int hooknum, struct sk_buff *skb, int af)
if (related)
return verdict;
ip_vs_fill_ip4hdr(skb_network_header(skb), &iph);
}
pd = ip_vs_proto_data_get(net, iph.protocol);
@ -1167,8 +1170,8 @@ ip_vs_out(unsigned int hooknum, struct sk_buff *skb, int af)
pp->protocol == IPPROTO_SCTP)) {
__be16 _ports[2], *pptr;
pptr = skb_header_pointer(skb, iph.len,
sizeof(_ports), _ports);
pptr = frag_safe_skb_hp(skb, iph.len,
sizeof(_ports), _ports, &iph);
if (pptr == NULL)
return NF_ACCEPT; /* Not for me */
if (ip_vs_lookup_real_service(net, af, iph.protocol,
@ -1468,7 +1471,7 @@ ip_vs_in_icmp_v6(struct sk_buff *skb, int *related, unsigned int hooknum)
*related = 1;
ic = skb_header_pointer(skb, iph->len, sizeof(_icmph), &_icmph);
ic = frag_safe_skb_hp(skb, iph->len, sizeof(_icmph), &_icmph, iph);
if (ic == NULL)
return NF_DROP;
@ -1483,6 +1486,11 @@ ip_vs_in_icmp_v6(struct sk_buff *skb, int *related, unsigned int hooknum)
*related = 0;
return NF_ACCEPT;
}
/* Fragment header that is before ICMP header tells us that:
* it's not an error message since they can't be fragmented.
*/
if (iph->flags & IP6T_FH_F_FRAG)
return NF_DROP;
IP_VS_DBG(8, "Incoming ICMPv6 (%d,%d) %pI6c->%pI6c\n",
ic->icmp6_type, ntohs(icmpv6_id(ic)),
@ -1514,10 +1522,20 @@ ip_vs_in_icmp_v6(struct sk_buff *skb, int *related, unsigned int hooknum)
IP_VS_DBG_PKT(11, AF_INET6, pp, skb, offs_ciph,
"Checking incoming ICMPv6 for");
/* The embedded headers contain source and dest in reverse order */
cp = pp->conn_in_get(AF_INET6, skb, &ciph, ciph.len, 1);
/* The embedded headers contain source and dest in reverse order
* if not from localhost
*/
cp = pp->conn_in_get(AF_INET6, skb, &ciph, ciph.len,
(hooknum == NF_INET_LOCAL_OUT) ? 0 : 1);
if (!cp)
return NF_ACCEPT;
/* VS/TUN, VS/DR and LOCALNODE just let it go */
if ((hooknum == NF_INET_LOCAL_OUT) &&
(IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ)) {
__ip_vs_conn_put(cp);
return NF_ACCEPT;
}
/* do the statistics and put it back */
ip_vs_in_stats(cp, skb);
@ -1590,6 +1608,12 @@ ip_vs_in(unsigned int hooknum, struct sk_buff *skb, int af)
#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);
@ -1614,13 +1638,16 @@ ip_vs_in(unsigned int hooknum, struct sk_buff *skb, int af)
pp = pd->pp;
/*
* Check if the packet belongs to an existing connection entry
* Only sched first IPv6 fragment.
*/
cp = pp->conn_in_get(af, skb, &iph, iph.len, 0);
if (unlikely(!cp) && !iph.fragoffs) {
/* No (second) fragments need to enter here, as nf_defrag_ipv6
* replayed fragment zero will already have created the cp
*/
int v;
/* Schedule and create new connection entry into &cp */
if (!pp->conn_schedule(af, skb, pd, &v, &cp))
return v;
}
@ -1629,6 +1656,14 @@ ip_vs_in(unsigned int hooknum, struct sk_buff *skb, int af)
/* 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)) {
/* 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");
IP_VS_DBG_PKT(7, af, pp, skb, 0, "unhandled fragment");
}
return NF_ACCEPT;
}
@ -1712,6 +1747,38 @@ ip_vs_local_request4(unsigned int hooknum, struct sk_buff *skb,
#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
@ -1851,6 +1918,14 @@ static struct nf_hook_ops ip_vs_ops[] __read_mostly = {
.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,

36
net/netfilter/ipvs/ip_vs_xmit.c
View file

@ -496,13 +496,15 @@ ip_vs_bypass_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
struct ip_vs_protocol *pp)
{
struct rt6_info *rt; /* Route to the other host */
struct ipv6hdr *iph = ipv6_hdr(skb);
struct ip_vs_iphdr iph;
int mtu;
EnterFunction(10);
ip_vs_fill_iph_skb(cp->af, skb, &iph);
if (!(rt = __ip_vs_get_out_rt_v6(skb, NULL, &iph->daddr, NULL, 0,
IP_VS_RT_MODE_NON_LOCAL)))
rt = __ip_vs_get_out_rt_v6(skb, NULL, &iph.daddr.in6, NULL, 0,
IP_VS_RT_MODE_NON_LOCAL);
if (!rt)
goto tx_error_icmp;
/* MTU checking */
@ -513,7 +515,9 @@ ip_vs_bypass_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
skb->dev = net->loopback_dev;
}
icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
/* only send ICMP too big on first fragment */
if (!iph.fragoffs)
icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
dst_release(&rt->dst);
IP_VS_DBG_RL("%s(): frag needed\n", __func__);
goto tx_error;
@ -685,7 +689,7 @@ ip_vs_nat_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
ip_vs_fill_iph_skb(cp->af, skb, &iph);
/* check if it is a connection of no-client-port */
if (unlikely(cp->flags & IP_VS_CONN_F_NO_CPORT)) {
if (unlikely(cp->flags & IP_VS_CONN_F_NO_CPORT && !iph.fragoffs)) {
__be16 _pt, *p;
p = skb_header_pointer(skb, iph.len, sizeof(_pt), &_pt);
if (p == NULL)
@ -735,7 +739,9 @@ ip_vs_nat_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
skb->dev = net->loopback_dev;
}
icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
/* only send ICMP too big on first fragment */
if (!iph.fragoffs)
icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
IP_VS_DBG_RL_PKT(0, AF_INET6, pp, skb, 0,
"ip_vs_nat_xmit_v6(): frag needed for");
goto tx_error_put;
@ -940,8 +946,10 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
unsigned int max_headroom; /* The extra header space needed */
int mtu;
int ret;
struct ip_vs_iphdr ipvsh;
EnterFunction(10);
ip_vs_fill_iph_skb(cp->af, skb, &ipvsh);
if (!(rt = __ip_vs_get_out_rt_v6(skb, cp->dest, &cp->daddr.in6,
&saddr, 1, (IP_VS_RT_MODE_LOCAL |
@ -970,7 +978,9 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
skb->dev = net->loopback_dev;
}
icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
/* only send ICMP too big on first fragment */
if (!ipvsh.fragoffs)
icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
IP_VS_DBG_RL("%s(): frag needed\n", __func__);
goto tx_error_put;
}
@ -1116,8 +1126,10 @@ ip_vs_dr_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
{
struct rt6_info *rt; /* Route to the other host */
int mtu;
struct ip_vs_iphdr iph;
EnterFunction(10);
ip_vs_fill_iph_skb(cp->af, skb, &iph);
if (!(rt = __ip_vs_get_out_rt_v6(skb, cp->dest, &cp->daddr.in6, NULL,
0, (IP_VS_RT_MODE_LOCAL |
@ -1136,7 +1148,9 @@ ip_vs_dr_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
skb->dev = net->loopback_dev;
}
icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
/* only send ICMP too big on first fragment */
if (!iph.fragoffs)
icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
dst_release(&rt->dst);
IP_VS_DBG_RL("%s(): frag needed\n", __func__);
goto tx_error;
@ -1308,8 +1322,10 @@ ip_vs_icmp_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
int rc;
int local;
int rt_mode;
struct ip_vs_iphdr iph;
EnterFunction(10);
ip_vs_fill_iph_skb(cp->af, skb, &iph);
/* The ICMP packet for VS/TUN, VS/DR and LOCALNODE will be
forwarded directly here, because there is no need to
@ -1372,7 +1388,9 @@ ip_vs_icmp_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
skb->dev = net->loopback_dev;
}
icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
/* only send ICMP too big on first fragment */
if (!iph.fragoffs)
icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
IP_VS_DBG_RL("%s(): frag needed\n", __func__);
goto tx_error_put;
}