From 961b3f81cb56d4f57954d4415ddd12da6ae09de9 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Tue, 11 Feb 2020 20:47:05 +0100 Subject: [PATCH] [10/11] icmp: introduce helper for nat'd source address in network device context Origin: https://git.zx2c4.com/wireguard-linux/commit?id=dece343674f61484816a13784d716f1d7098fa05 Bug-Debian: https://bugs.debian.org/953569 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 Cc: Florian Westphal Signed-off-by: David S. Miller [bwh: commits 0b41713b606694257b90d61ba7e2712d8457648b and a8e41f6033a0c5633d55d6e35993c9e2005d872f "icmp: allow icmpv6_ndo_send to work with CONFIG_IPV6=n" upstream] Gbp-Pq: Topic features/all/wireguard Gbp-Pq: Name 0010-icmp-introduce-helper-for-nat-d-source-address-in-ne.patch --- include/linux/icmpv6.h | 10 ++++++++++ include/net/icmp.h | 6 ++++++ net/ipv4/icmp.c | 33 +++++++++++++++++++++++++++++++++ net/ipv6/ip6_icmp.c | 34 ++++++++++++++++++++++++++++++++++ 4 files changed, 83 insertions(+) diff --git a/include/linux/icmpv6.h b/include/linux/icmpv6.h index ef1cbb5f454..33d37960231 100644 --- a/include/linux/icmpv6.h +++ b/include/linux/icmpv6.h @@ -22,12 +22,22 @@ extern int inet6_unregister_icmp_sender(ip6_icmp_send_t *fn); int ip6_err_gen_icmpv6_unreach(struct sk_buff *skb, int nhs, int type, unsigned int data_len); +#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 + #else static inline void icmpv6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info) { +} +static inline void icmpv6_ndo_send(struct sk_buff *skb, + u8 type, u8 code, __u32 info) +{ } #endif diff --git a/include/net/icmp.h b/include/net/icmp.h index 5d4bfdba9ad..9ac2d2672a9 100644 --- a/include/net/icmp.h +++ b/include/net/icmp.h @@ -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); diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c index 18068ed42f2..f369e7ce685 100644 --- a/net/ipv4/icmp.c +++ b/net/ipv4/icmp.c @@ -748,6 +748,39 @@ out:; } EXPORT_SYMBOL(__icmp_send); +#if IS_ENABLED(CONFIG_NF_NAT) +#include +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) { diff --git a/net/ipv6/ip6_icmp.c b/net/ipv6/ip6_icmp.c index 02045494c24..e0086758b6e 100644 --- a/net/ipv6/ip6_icmp.c +++ b/net/ipv6/ip6_icmp.c @@ -45,4 +45,38 @@ out: rcu_read_unlock(); } EXPORT_SYMBOL(icmpv6_send); + +#if IS_ENABLED(CONFIG_NF_NAT) +#include +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 -- 2.30.2