From e110861f86094cd78cc85593b873970092deb43a Mon Sep 17 00:00:00 2001 From: Lorenzo Colitti Date: Tue, 13 May 2014 10:17:33 -0700 Subject: [PATCH] net: add a sysctl to reflect the fwmark on replies Kernel-originated IP packets that have no user socket associated with them (e.g., ICMP errors and echo replies, TCP RSTs, etc.) are emitted with a mark of zero. Add a sysctl to make them have the same mark as the packet they are replying to. This allows an administrator that wishes to do so to use mark-based routing, firewalling, etc. for these replies by marking the original packets inbound. Tested using user-mode linux: - ICMP/ICMPv6 echo replies and errors. - TCP RST packets (IPv4 and IPv6). Signed-off-by: Lorenzo Colitti Signed-off-by: David S. Miller --- include/net/ip.h | 3 +++ include/net/ipv6.h | 3 +++ include/net/netns/ipv4.h | 2 ++ include/net/netns/ipv6.h | 1 + net/ipv4/icmp.c | 11 +++++++++-- net/ipv4/ip_output.c | 3 ++- net/ipv4/sysctl_net_ipv4.c | 7 +++++++ net/ipv6/icmp.c | 6 ++++++ net/ipv6/sysctl_net_ipv6.c | 7 +++++++ net/ipv6/tcp_ipv6.c | 1 + 10 files changed, 41 insertions(+), 3 deletions(-) diff --git a/include/net/ip.h b/include/net/ip.h index 55752985c144..14c50a1650ef 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -231,6 +231,9 @@ void ipfrag_init(void); void ip_static_sysctl_init(void); +#define IP4_REPLY_MARK(net, mark) \ + ((net)->ipv4.sysctl_fwmark_reflect ? (mark) : 0) + static inline bool ip_is_fragment(const struct iphdr *iph) { return (iph->frag_off & htons(IP_MF | IP_OFFSET)) != 0; diff --git a/include/net/ipv6.h b/include/net/ipv6.h index 5b40ad297b8c..ba810d0546bc 100644 --- a/include/net/ipv6.h +++ b/include/net/ipv6.h @@ -113,6 +113,9 @@ struct frag_hdr { #define IP6_MF 0x0001 #define IP6_OFFSET 0xFFF8 +#define IP6_REPLY_MARK(net, mark) \ + ((net)->ipv6.sysctl.fwmark_reflect ? (mark) : 0) + #include /* sysctls */ diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h index b2704fd0ec80..a32fc4d705da 100644 --- a/include/net/netns/ipv4.h +++ b/include/net/netns/ipv4.h @@ -77,6 +77,8 @@ struct netns_ipv4 { int sysctl_ip_no_pmtu_disc; int sysctl_ip_fwd_use_pmtu; + int sysctl_fwmark_reflect; + struct ping_group_range ping_group_range; atomic_t dev_addr_genid; diff --git a/include/net/netns/ipv6.h b/include/net/netns/ipv6.h index 21edaf1f7916..19d3446e59d2 100644 --- a/include/net/netns/ipv6.h +++ b/include/net/netns/ipv6.h @@ -30,6 +30,7 @@ struct netns_sysctl_ipv6 { int flowlabel_consistency; int icmpv6_time; int anycast_src_echo_reply; + int fwmark_reflect; }; struct netns_ipv6 { diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c index fe52666dc43c..79c3d947a481 100644 --- a/net/ipv4/icmp.c +++ b/net/ipv4/icmp.c @@ -337,6 +337,7 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) struct sock *sk; struct inet_sock *inet; __be32 daddr, saddr; + u32 mark = IP4_REPLY_MARK(net, skb->mark); if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb)) return; @@ -349,6 +350,7 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) icmp_param->data.icmph.checksum = 0; inet->tos = ip_hdr(skb)->tos; + sk->sk_mark = mark; daddr = ipc.addr = ip_hdr(skb)->saddr; saddr = fib_compute_spec_dst(skb); ipc.opt = NULL; @@ -364,6 +366,7 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) memset(&fl4, 0, sizeof(fl4)); fl4.daddr = daddr; fl4.saddr = saddr; + fl4.flowi4_mark = mark; fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos); fl4.flowi4_proto = IPPROTO_ICMP; security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); @@ -382,7 +385,7 @@ static struct rtable *icmp_route_lookup(struct net *net, struct flowi4 *fl4, struct sk_buff *skb_in, const struct iphdr *iph, - __be32 saddr, u8 tos, + __be32 saddr, u8 tos, u32 mark, int type, int code, struct icmp_bxm *param) { @@ -394,6 +397,7 @@ static struct rtable *icmp_route_lookup(struct net *net, fl4->daddr = (param->replyopts.opt.opt.srr ? param->replyopts.opt.opt.faddr : iph->saddr); fl4->saddr = saddr; + fl4->flowi4_mark = mark; fl4->flowi4_tos = RT_TOS(tos); fl4->flowi4_proto = IPPROTO_ICMP; fl4->fl4_icmp_type = type; @@ -491,6 +495,7 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info) struct flowi4 fl4; __be32 saddr; u8 tos; + u32 mark; struct net *net; struct sock *sk; @@ -592,6 +597,7 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info) tos = icmp_pointers[type].error ? ((iph->tos & IPTOS_TOS_MASK) | IPTOS_PREC_INTERNETCONTROL) : iph->tos; + mark = IP4_REPLY_MARK(net, skb_in->mark); if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb_in)) goto out_unlock; @@ -608,13 +614,14 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info) icmp_param->skb = skb_in; icmp_param->offset = skb_network_offset(skb_in); inet_sk(sk)->tos = tos; + sk->sk_mark = mark; ipc.addr = iph->saddr; ipc.opt = &icmp_param->replyopts.opt; ipc.tx_flags = 0; ipc.ttl = 0; ipc.tos = -1; - rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, + rt = icmp_route_lookup(net, &fl4, skb_in, iph, saddr, tos, mark, type, code, icmp_param); if (IS_ERR(rt)) goto out_unlock; diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 6aa4380fde1a..6e231ab58d65 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -1546,7 +1546,8 @@ void ip_send_unicast_reply(struct net *net, struct sk_buff *skb, __be32 daddr, daddr = replyopts.opt.opt.faddr; } - flowi4_init_output(&fl4, arg->bound_dev_if, 0, + flowi4_init_output(&fl4, arg->bound_dev_if, + IP4_REPLY_MARK(net, skb->mark), RT_TOS(arg->tos), RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol, ip_reply_arg_flowi_flags(arg), diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c index 5cde8f263d40..f50d51850285 100644 --- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -838,6 +838,13 @@ static struct ctl_table ipv4_net_table[] = { .mode = 0644, .proc_handler = proc_dointvec, }, + { + .procname = "fwmark_reflect", + .data = &init_net.ipv4.sysctl_fwmark_reflect, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec, + }, { } }; diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c index 8d3952796d39..f6c84a6eb238 100644 --- a/net/ipv6/icmp.c +++ b/net/ipv6/icmp.c @@ -400,6 +400,7 @@ static void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info) int len; int hlimit; int err = 0; + u32 mark = IP6_REPLY_MARK(net, skb->mark); if ((u8 *)hdr < skb->head || (skb_network_header(skb) + sizeof(*hdr)) > skb_tail_pointer(skb)) @@ -466,6 +467,7 @@ static void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info) fl6.daddr = hdr->saddr; if (saddr) fl6.saddr = *saddr; + fl6.flowi6_mark = mark; fl6.flowi6_oif = iif; fl6.fl6_icmp_type = type; fl6.fl6_icmp_code = code; @@ -474,6 +476,7 @@ static void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info) sk = icmpv6_xmit_lock(net); if (sk == NULL) return; + sk->sk_mark = mark; np = inet6_sk(sk); if (!icmpv6_xrlim_allow(sk, type, &fl6)) @@ -551,6 +554,7 @@ static void icmpv6_echo_reply(struct sk_buff *skb) int err = 0; int hlimit; u8 tclass; + u32 mark = IP6_REPLY_MARK(net, skb->mark); saddr = &ipv6_hdr(skb)->daddr; @@ -569,11 +573,13 @@ static void icmpv6_echo_reply(struct sk_buff *skb) fl6.saddr = *saddr; fl6.flowi6_oif = skb->dev->ifindex; fl6.fl6_icmp_type = ICMPV6_ECHO_REPLY; + fl6.flowi6_mark = mark; security_skb_classify_flow(skb, flowi6_to_flowi(&fl6)); sk = icmpv6_xmit_lock(net); if (sk == NULL) return; + sk->sk_mark = mark; np = inet6_sk(sk); if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr)) diff --git a/net/ipv6/sysctl_net_ipv6.c b/net/ipv6/sysctl_net_ipv6.c index 7f405a168822..058f3eca2e53 100644 --- a/net/ipv6/sysctl_net_ipv6.c +++ b/net/ipv6/sysctl_net_ipv6.c @@ -38,6 +38,13 @@ static struct ctl_table ipv6_table_template[] = { .mode = 0644, .proc_handler = proc_dointvec }, + { + .procname = "fwmark_reflect", + .data = &init_net.ipv6.sysctl.fwmark_reflect, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec + }, { } }; diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 3a267bf14f2f..c54976a44425 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -812,6 +812,7 @@ static void tcp_v6_send_response(struct sk_buff *skb, u32 seq, u32 ack, u32 win, fl6.flowi6_oif = inet6_iif(skb); else fl6.flowi6_oif = oif; + fl6.flowi6_mark = IP6_REPLY_MARK(net, skb->mark); fl6.fl6_dport = t1->dest; fl6.fl6_sport = t1->source; security_skb_classify_flow(skb, flowi6_to_flowi(&fl6)); -- 2.20.1