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bridge_netfilter: No ICMP packet on IPv4 fragmentation error

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When bridge netfilter re-fragments an IP packet for output, all
packets that can not be re-fragmented to their original input size
should be silently discarded.

However, current bridge netfilter output path generates an ICMP packet
with 'size exceeded MTU' message for such packets, this is a bug.

This patch refactors the ip_fragment() API to allow two separate
use cases. The bridge netfilter user case will not
send ICMP, the routing output will, as before.

Signed-off-by: Andy Zhou <azhou@nicira.com>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Andy Zhou 2015-05-15 14:15:37 -07:00 committed by David S. Miller
parent 8bc04864ac
commit 49d16b23cd
3 changed files with 50 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/net/ip.h
View File

@ -108,7 +108,7 @@ int ip_local_deliver(struct sk_buff *skb);
int ip_mr_input(struct sk_buff *skb);
int ip_output(struct sock *sk, struct sk_buff *skb);
int ip_mc_output(struct sock *sk, struct sk_buff *skb);
int ip_fragment(struct sock *sk, struct sk_buff *skb,
int ip_do_fragment(struct sock *sk, struct sk_buff *skb,
int (*output)(struct sock *, struct sk_buff *));
int ip_do_nat(struct sk_buff *skb);
void ip_send_check(struct iphdr *ip);

21
net/bridge/br_netfilter.c
View File

@ -853,6 +853,25 @@ static int br_nf_push_frag_xmit(struct sock *sk, struct sk_buff *skb)
return br_dev_queue_push_xmit(sk, skb);
}
static int br_nf_ip_fragment(struct sock *sk, struct sk_buff *skb,
int (*output)(struct sock *, struct sk_buff *))
{
unsigned int mtu = ip_skb_dst_mtu(skb);
struct iphdr *iph = ip_hdr(skb);
struct rtable *rt = skb_rtable(skb);
struct net_device *dev = rt->dst.dev;
if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) ||
(IPCB(skb)->frag_max_size &&
IPCB(skb)->frag_max_size > mtu))) {
IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
kfree_skb(skb);
return -EMSGSIZE;
}
return ip_do_fragment(sk, skb, output);
}
static int br_nf_dev_queue_xmit(struct sock *sk, struct sk_buff *skb)
{
int ret;
@ -886,7 +905,7 @@ static int br_nf_dev_queue_xmit(struct sock *sk, struct sk_buff *skb)
skb_copy_from_linear_data_offset(skb, -data->size, data->mac,
data->size);
ret = ip_fragment(sk, skb, br_nf_push_frag_xmit);
ret = br_nf_ip_fragment(sk, skb, br_nf_push_frag_xmit);
} else {
nf_bridge_info_free(skb);
ret = br_dev_queue_push_xmit(sk, skb);

38
net/ipv4/ip_output.c
View File

@ -83,6 +83,9 @@
int sysctl_ip_default_ttl __read_mostly = IPDEFTTL;
EXPORT_SYMBOL(sysctl_ip_default_ttl);
static int ip_fragment(struct sock *sk, struct sk_buff *skb,
int (*output)(struct sock *, struct sk_buff *));
/* Generate a checksum for an outgoing IP datagram. */
void ip_send_check(struct iphdr *iph)
{
@ -478,6 +481,28 @@ static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
skb_copy_secmark(to, from);
}
static int ip_fragment(struct sock *sk, struct sk_buff *skb,
int (*output)(struct sock *, struct sk_buff *))
{
struct iphdr *iph = ip_hdr(skb);
unsigned int mtu = ip_skb_dst_mtu(skb);
if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) ||
(IPCB(skb)->frag_max_size &&
IPCB(skb)->frag_max_size > mtu))) {
struct rtable *rt = skb_rtable(skb);
struct net_device *dev = rt->dst.dev;
IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
htonl(mtu));
kfree_skb(skb);
return -EMSGSIZE;
}
return ip_do_fragment(sk, skb, output);
}
/*
* This IP datagram is too large to be sent in one piece. Break it up into
* smaller pieces (each of size equal to IP header plus
@ -485,7 +510,7 @@ static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
* single device frame, and queue such a frame for sending.
*/
int ip_fragment(struct sock *sk, struct sk_buff *skb,
int ip_do_fragment(struct sock *sk, struct sk_buff *skb,
int (*output)(struct sock *, struct sk_buff *))
{
struct iphdr *iph;
@ -507,15 +532,6 @@ int ip_fragment(struct sock *sk, struct sk_buff *skb,
iph = ip_hdr(skb);
mtu = ip_skb_dst_mtu(skb);
if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) ||
(IPCB(skb)->frag_max_size &&
IPCB(skb)->frag_max_size > mtu))) {
IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
htonl(mtu));
kfree_skb(skb);
return -EMSGSIZE;
}
/*
* Setup starting values.
@ -751,7 +767,7 @@ fail:
IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
return err;
}
EXPORT_SYMBOL(ip_fragment);
EXPORT_SYMBOL(ip_do_fragment);
int
ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)