The out_rt functions check to see if the mtu is large enough for the packet
and, if not, send icmp messages (TOOBIG or DEST_UNREACH) to the source and
bail out. We needed the ability to send ICMP from the out_rt_v6 function
and DEST_UNREACH from the out_rt function, so we just pulled it out into a
common function.
Signed-off-by: Alex Gartrell <agartrell@xxxxxx>
---
net/netfilter/ipvs/ip_vs_xmit.c | 77 +++++++++++++++++++++++++++--------------
1 file changed, 51 insertions(+), 26 deletions(-)
diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
index 034a282..fa2fdd7 100644
--- a/net/netfilter/ipvs/ip_vs_xmit.c
+++ b/net/netfilter/ipvs/ip_vs_xmit.c
@@ -213,17 +213,57 @@ static inline void maybe_update_pmtu(int skb_af, struct sk_buff *skb, int mtu)
ort->dst.ops->update_pmtu(&ort->dst, sk, NULL, mtu);
}
+static inline bool ensure_mtu_is_adequate(int skb_af, int rt_mode,
+ struct ip_vs_iphdr *ipvsh,
+ struct sk_buff *skb, int mtu)
+{
+#ifdef CONFIG_IP_VS_IPV6
+ if (skb_af == AF_INET6) {
+ struct net *net = dev_net(skb_dst(skb)->dev);
+
+ if (unlikely(__mtu_check_toobig_v6(skb, mtu))) {
+ if (!skb->dev)
+ skb->dev = net->loopback_dev;
+ /* only send ICMP too big on first fragment */
+ if (!ipvsh->fragoffs)
+ icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
+ IP_VS_DBG(1, "frag needed for %pI6c\n",
+ &ipv6_hdr(skb)->saddr);
+ return false;
+ }
+ } else
+#endif
+ {
+ struct netns_ipvs *ipvs = net_ipvs(skb_net(skb));
+
+ /* If we're going to tunnel the packet and pmtu discovery
+ * is disabled, we'll just fragment it anyway
+ */
+ if ((rt_mode & IP_VS_RT_MODE_TUNNEL) && !sysctl_pmtu_disc(ipvs))
+ return true;
+
+ if (unlikely(ip_hdr(skb)->frag_off & htons(IP_DF) &&
+ skb->len > mtu && !skb_is_gso(skb))) {
+ icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
+ htonl(mtu));
+ IP_VS_DBG(1, "frag needed for %pI4\n",
+ &ip_hdr(skb)->saddr);
+ return false;
+ }
+ }
+
+ return true;
+}
+
/* Get route to destination or remote server */
static int
__ip_vs_get_out_rt(int skb_af, struct sk_buff *skb, struct ip_vs_dest *dest,
- __be32 daddr, int rt_mode, __be32 *ret_saddr)
+ __be32 daddr, int rt_mode, __be32 *ret_saddr,
+ struct ip_vs_iphdr *ipvsh)
{
struct net *net = dev_net(skb_dst(skb)->dev);
- struct netns_ipvs *ipvs = net_ipvs(net);
struct ip_vs_dest_dst *dest_dst;
struct rtable *rt; /* Route to the other host */
- struct iphdr *iph;
- __be16 df;
int mtu;
int local, noref = 1;
@@ -279,7 +319,6 @@ __ip_vs_get_out_rt(int skb_af, struct sk_buff *skb, struct ip_vs_dest *dest,
" daddr=%pI4\n", &dest->addr.ip);
goto err_put;
}
- iph = ip_hdr(skb);
if (unlikely(local)) {
/* skb to local stack, preserve old route */
@@ -290,7 +329,6 @@ __ip_vs_get_out_rt(int skb_af, struct sk_buff *skb, struct ip_vs_dest *dest,
if (likely(!(rt_mode & IP_VS_RT_MODE_TUNNEL))) {
mtu = dst_mtu(&rt->dst);
- df = iph->frag_off & htons(IP_DF);
} else {
mtu = dst_mtu(&rt->dst) - sizeof(struct iphdr);
if (mtu < 68) {
@@ -298,16 +336,10 @@ __ip_vs_get_out_rt(int skb_af, struct sk_buff *skb, struct ip_vs_dest *dest,
goto err_put;
}
maybe_update_pmtu(skb_af, skb, mtu);
- /* MTU check allowed? */
- df = sysctl_pmtu_disc(ipvs) ? iph->frag_off & htons(IP_DF) : 0;
}
- /* MTU checking */
- if (unlikely(df && skb->len > mtu && !skb_is_gso(skb))) {
- icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
- IP_VS_DBG(1, "frag needed for %pI4\n", &iph->saddr);
+ if (!ensure_mtu_is_adequate(skb_af, rt_mode, ipvsh, skb, mtu))
goto err_put;
- }
skb_dst_drop(skb);
if (noref) {
@@ -450,15 +482,8 @@ __ip_vs_get_out_rt_v6(int skb_af, struct sk_buff *skb, struct ip_vs_dest *dest,
maybe_update_pmtu(skb_af, skb, mtu);
}
- if (unlikely(__mtu_check_toobig_v6(skb, mtu))) {
- if (!skb->dev)
- skb->dev = net->loopback_dev;
- /* only send ICMP too big on first fragment */
- if (!ipvsh->fragoffs)
- icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
- IP_VS_DBG(1, "frag needed for %pI6c\n", &ipv6_hdr(skb)->saddr);
+ if (!ensure_mtu_is_adequate(skb_af, rt_mode, ipvsh, skb, mtu))
goto err_put;
- }
skb_dst_drop(skb);
if (noref) {
@@ -565,7 +590,7 @@ ip_vs_bypass_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
rcu_read_lock();
if (__ip_vs_get_out_rt(cp->af, skb, NULL, iph->daddr,
- IP_VS_RT_MODE_NON_LOCAL, NULL) < 0)
+ IP_VS_RT_MODE_NON_LOCAL, NULL, ipvsh) < 0)
goto tx_error;
ip_send_check(iph);
@@ -644,7 +669,7 @@ ip_vs_nat_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
local = __ip_vs_get_out_rt(cp->af, skb, cp->dest, cp->daddr.ip,
IP_VS_RT_MODE_LOCAL |
IP_VS_RT_MODE_NON_LOCAL |
- IP_VS_RT_MODE_RDR, NULL);
+ IP_VS_RT_MODE_RDR, NULL, ipvsh);
if (local < 0)
goto tx_error;
rt = skb_rtable(skb);
@@ -841,7 +866,7 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
IP_VS_RT_MODE_LOCAL |
IP_VS_RT_MODE_NON_LOCAL |
IP_VS_RT_MODE_CONNECT |
- IP_VS_RT_MODE_TUNNEL, &saddr);
+ IP_VS_RT_MODE_TUNNEL, &saddr, ipvsh);
if (local < 0)
goto tx_error;
if (local) {
@@ -1032,7 +1057,7 @@ ip_vs_dr_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
local = __ip_vs_get_out_rt(cp->af, skb, cp->dest, cp->daddr.ip,
IP_VS_RT_MODE_LOCAL |
IP_VS_RT_MODE_NON_LOCAL |
- IP_VS_RT_MODE_KNOWN_NH, NULL);
+ IP_VS_RT_MODE_KNOWN_NH, NULL, ipvsh);
if (local < 0)
goto tx_error;
if (local) {
@@ -1137,7 +1162,7 @@ ip_vs_icmp_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
IP_VS_RT_MODE_RDR : IP_VS_RT_MODE_NON_LOCAL;
rcu_read_lock();
local = __ip_vs_get_out_rt(cp->af, skb, cp->dest, cp->daddr.ip, rt_mode,
- NULL);
+ NULL, iph);
if (local < 0)
goto tx_error;
rt = skb_rtable(skb);
--
1.8.1
--
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