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icmp: introduce helper for nat'd source address in network device context 

This introduces a helper function to be called only by network drivers
that wraps calls to icmp[v6]_send in a conntrack transformation, in case
NAT has been used. We don't want to pollute the non-driver path, though,
so we introduce this as a helper to be called by places that actually
make use of this, as suggested by Florian.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jason A. Donenfeld 2020-02-11 20:47:05 +01:00 committed by David S. Miller
parent 07134cf696
commit 0b41713b60
4 changed files with 79 additions and 0 deletions
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6
include/linux/icmpv6.h
View File

@ -31,6 +31,12 @@ static inline void icmpv6_send(struct sk_buff *skb,
}
#endif
#if IS_ENABLED(CONFIG_NF_NAT)
void icmpv6_ndo_send(struct sk_buff *skb_in, u8 type, u8 code, __u32 info);
#else
#define icmpv6_ndo_send icmpv6_send
#endif
extern int icmpv6_init(void);
extern int icmpv6_err_convert(u8 type, u8 code,
int *err);

6
include/net/icmp.h
View File

@ -43,6 +43,12 @@ static inline void icmp_send(struct sk_buff *skb_in, int type, int code, __be32
__icmp_send(skb_in, type, code, info, &IPCB(skb_in)->opt);
}
#if IS_ENABLED(CONFIG_NF_NAT)
void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info);
#else
#define icmp_ndo_send icmp_send
#endif
int icmp_rcv(struct sk_buff *skb);
int icmp_err(struct sk_buff *skb, u32 info);
int icmp_init(void);

33
net/ipv4/icmp.c
View File

@ -748,6 +748,39 @@ out:;
}
EXPORT_SYMBOL(__icmp_send);
#if IS_ENABLED(CONFIG_NF_NAT)
#include <net/netfilter/nf_conntrack.h>
void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info)
{
struct sk_buff *cloned_skb = NULL;
enum ip_conntrack_info ctinfo;
struct nf_conn *ct;
__be32 orig_ip;
ct = nf_ct_get(skb_in, &ctinfo);
if (!ct || !(ct->status & IPS_SRC_NAT)) {
icmp_send(skb_in, type, code, info);
return;
}
if (skb_shared(skb_in))
skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC);
if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head ||
(skb_network_header(skb_in) + sizeof(struct iphdr)) >
skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in,
skb_network_offset(skb_in) + sizeof(struct iphdr))))
goto out;
orig_ip = ip_hdr(skb_in)->saddr;
ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip;
icmp_send(skb_in, type, code, info);
ip_hdr(skb_in)->saddr = orig_ip;
out:
consume_skb(cloned_skb);
}
EXPORT_SYMBOL(icmp_ndo_send);
#endif
static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
{

34
net/ipv6/ip6_icmp.c
View File

@ -45,4 +45,38 @@ void icmpv6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info)
rcu_read_unlock();
}
EXPORT_SYMBOL(icmpv6_send);
#if IS_ENABLED(CONFIG_NF_NAT)
#include <net/netfilter/nf_conntrack.h>
void icmpv6_ndo_send(struct sk_buff *skb_in, u8 type, u8 code, __u32 info)
{
struct sk_buff *cloned_skb = NULL;
enum ip_conntrack_info ctinfo;
struct in6_addr orig_ip;
struct nf_conn *ct;
ct = nf_ct_get(skb_in, &ctinfo);
if (!ct || !(ct->status & IPS_SRC_NAT)) {
icmpv6_send(skb_in, type, code, info);
return;
}
if (skb_shared(skb_in))
skb_in = cloned_skb = skb_clone(skb_in, GFP_ATOMIC);
if (unlikely(!skb_in || skb_network_header(skb_in) < skb_in->head ||
(skb_network_header(skb_in) + sizeof(struct ipv6hdr)) >
skb_tail_pointer(skb_in) || skb_ensure_writable(skb_in,
skb_network_offset(skb_in) + sizeof(struct ipv6hdr))))
goto out;
orig_ip = ipv6_hdr(skb_in)->saddr;
ipv6_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.in6;
icmpv6_send(skb_in, type, code, info);
ipv6_hdr(skb_in)->saddr = orig_ip;
out:
consume_skb(cloned_skb);
}
EXPORT_SYMBOL(icmpv6_ndo_send);
#endif
#endif