From c8d7b98bec43faaa6583c3135030be5eb4693acb Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Fri, 26 Sep 2014 14:35:15 +0200 Subject: [PATCH] netfilter: move nf_send_resetX() code to nf_reject_ipvX modules Move nf_send_reset() and nf_send_reset6() to nf_reject_ipv4 and nf_reject_ipv6 respectively. This code is shared by x_tables and nf_tables. Signed-off-by: Pablo Neira Ayuso --- include/net/netfilter/ipv4/nf_reject.h | 118 +----------------- net/ipv4/netfilter/Kconfig | 6 + net/ipv4/netfilter/Makefile | 3 + net/ipv4/netfilter/nf_reject_ipv4.c | 127 +++++++++++++++++++ net/ipv6/netfilter/Kconfig | 6 + net/ipv6/netfilter/Makefile | 3 + net/ipv6/netfilter/nf_reject_ipv6.c | 163 +++++++++++++++++++++++++ 7 files changed, 309 insertions(+), 117 deletions(-) create mode 100644 net/ipv4/netfilter/nf_reject_ipv4.c create mode 100644 net/ipv6/netfilter/nf_reject_ipv6.c diff --git a/include/net/netfilter/ipv4/nf_reject.h b/include/net/netfilter/ipv4/nf_reject.h index 8ce06385a552..e8427193c777 100644 --- a/include/net/netfilter/ipv4/nf_reject.h +++ b/include/net/netfilter/ipv4/nf_reject.h @@ -1,10 +1,6 @@ #ifndef _IPV4_NF_REJECT_H #define _IPV4_NF_REJECT_H -#include -#include -#include -#include #include static inline void nf_send_unreach(struct sk_buff *skb_in, int code) @@ -12,118 +8,6 @@ static inline void nf_send_unreach(struct sk_buff *skb_in, int code) icmp_send(skb_in, ICMP_DEST_UNREACH, code, 0); } -/* Send RST reply */ -static void nf_send_reset(struct sk_buff *oldskb, int hook) -{ - struct sk_buff *nskb; - const struct iphdr *oiph; - struct iphdr *niph; - const struct tcphdr *oth; - struct tcphdr _otcph, *tcph; - - /* IP header checks: fragment. */ - if (ip_hdr(oldskb)->frag_off & htons(IP_OFFSET)) - return; - - oth = skb_header_pointer(oldskb, ip_hdrlen(oldskb), - sizeof(_otcph), &_otcph); - if (oth == NULL) - return; - - /* No RST for RST. */ - if (oth->rst) - return; - - if (skb_rtable(oldskb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) - return; - - /* Check checksum */ - if (nf_ip_checksum(oldskb, hook, ip_hdrlen(oldskb), IPPROTO_TCP)) - return; - oiph = ip_hdr(oldskb); - - nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct tcphdr) + - LL_MAX_HEADER, GFP_ATOMIC); - if (!nskb) - return; - - skb_reserve(nskb, LL_MAX_HEADER); - - skb_reset_network_header(nskb); - niph = (struct iphdr *)skb_put(nskb, sizeof(struct iphdr)); - niph->version = 4; - niph->ihl = sizeof(struct iphdr) / 4; - niph->tos = 0; - niph->id = 0; - niph->frag_off = htons(IP_DF); - niph->protocol = IPPROTO_TCP; - niph->check = 0; - niph->saddr = oiph->daddr; - niph->daddr = oiph->saddr; - - skb_reset_transport_header(nskb); - tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr)); - memset(tcph, 0, sizeof(*tcph)); - tcph->source = oth->dest; - tcph->dest = oth->source; - tcph->doff = sizeof(struct tcphdr) / 4; - - if (oth->ack) - tcph->seq = oth->ack_seq; - else { - tcph->ack_seq = htonl(ntohl(oth->seq) + oth->syn + oth->fin + - oldskb->len - ip_hdrlen(oldskb) - - (oth->doff << 2)); - tcph->ack = 1; - } - - tcph->rst = 1; - tcph->check = ~tcp_v4_check(sizeof(struct tcphdr), niph->saddr, - niph->daddr, 0); - nskb->ip_summed = CHECKSUM_PARTIAL; - nskb->csum_start = (unsigned char *)tcph - nskb->head; - nskb->csum_offset = offsetof(struct tcphdr, check); - - /* ip_route_me_harder expects skb->dst to be set */ - skb_dst_set_noref(nskb, skb_dst(oldskb)); - - nskb->protocol = htons(ETH_P_IP); - if (ip_route_me_harder(nskb, RTN_UNSPEC)) - goto free_nskb; - - niph->ttl = ip4_dst_hoplimit(skb_dst(nskb)); - - /* "Never happens" */ - if (nskb->len > dst_mtu(skb_dst(nskb))) - goto free_nskb; - - nf_ct_attach(nskb, oldskb); - -#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) - /* If we use ip_local_out for bridged traffic, the MAC source on - * the RST will be ours, instead of the destination's. This confuses - * some routers/firewalls, and they drop the packet. So we need to - * build the eth header using the original destination's MAC as the - * source, and send the RST packet directly. - */ - if (oldskb->nf_bridge) { - struct ethhdr *oeth = eth_hdr(oldskb); - nskb->dev = oldskb->nf_bridge->physindev; - niph->tot_len = htons(nskb->len); - ip_send_check(niph); - if (dev_hard_header(nskb, nskb->dev, ntohs(nskb->protocol), - oeth->h_source, oeth->h_dest, nskb->len) < 0) - goto free_nskb; - dev_queue_xmit(nskb); - } else -#endif - ip_local_out(nskb); - - return; - - free_nskb: - kfree_skb(nskb); -} - +void nf_send_reset(struct sk_buff *oldskb, int hook); #endif /* _IPV4_NF_REJECT_H */ diff --git a/net/ipv4/netfilter/Kconfig b/net/ipv4/netfilter/Kconfig index 345242a79db6..4c019d5c3f57 100644 --- a/net/ipv4/netfilter/Kconfig +++ b/net/ipv4/netfilter/Kconfig @@ -61,8 +61,13 @@ config NFT_CHAIN_ROUTE_IPV4 fields such as the source, destination, type of service and the packet mark. +config NF_REJECT_IPV4 + tristate "IPv4 packet rejection" + default m if NETFILTER_ADVANCED=n + config NFT_REJECT_IPV4 depends on NF_TABLES_IPV4 + select NF_REJECT_IPV4 default NFT_REJECT tristate @@ -208,6 +213,7 @@ config IP_NF_FILTER config IP_NF_TARGET_REJECT tristate "REJECT target support" depends on IP_NF_FILTER + select NF_REJECT_IPV4 default m if NETFILTER_ADVANCED=n help The REJECT target allows a filtering rule to specify that an ICMP diff --git a/net/ipv4/netfilter/Makefile b/net/ipv4/netfilter/Makefile index 14488cc5fd2c..f4cef5af0969 100644 --- a/net/ipv4/netfilter/Makefile +++ b/net/ipv4/netfilter/Makefile @@ -23,6 +23,9 @@ obj-$(CONFIG_NF_DEFRAG_IPV4) += nf_defrag_ipv4.o obj-$(CONFIG_NF_LOG_ARP) += nf_log_arp.o obj-$(CONFIG_NF_LOG_IPV4) += nf_log_ipv4.o +# reject +obj-$(CONFIG_NF_REJECT_IPV4) += nf_reject_ipv4.o + # NAT helpers (nf_conntrack) obj-$(CONFIG_NF_NAT_H323) += nf_nat_h323.o obj-$(CONFIG_NF_NAT_PPTP) += nf_nat_pptp.o diff --git a/net/ipv4/netfilter/nf_reject_ipv4.c b/net/ipv4/netfilter/nf_reject_ipv4.c new file mode 100644 index 000000000000..b023b4eb1a96 --- /dev/null +++ b/net/ipv4/netfilter/nf_reject_ipv4.c @@ -0,0 +1,127 @@ +/* (C) 1999-2001 Paul `Rusty' Russell + * (C) 2002-2004 Netfilter Core Team + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include +#include +#include +#include +#include + +/* Send RST reply */ +void nf_send_reset(struct sk_buff *oldskb, int hook) +{ + struct sk_buff *nskb; + const struct iphdr *oiph; + struct iphdr *niph; + const struct tcphdr *oth; + struct tcphdr _otcph, *tcph; + + /* IP header checks: fragment. */ + if (ip_hdr(oldskb)->frag_off & htons(IP_OFFSET)) + return; + + oth = skb_header_pointer(oldskb, ip_hdrlen(oldskb), + sizeof(_otcph), &_otcph); + if (oth == NULL) + return; + + /* No RST for RST. */ + if (oth->rst) + return; + + if (skb_rtable(oldskb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST)) + return; + + /* Check checksum */ + if (nf_ip_checksum(oldskb, hook, ip_hdrlen(oldskb), IPPROTO_TCP)) + return; + oiph = ip_hdr(oldskb); + + nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct tcphdr) + + LL_MAX_HEADER, GFP_ATOMIC); + if (!nskb) + return; + + skb_reserve(nskb, LL_MAX_HEADER); + + skb_reset_network_header(nskb); + niph = (struct iphdr *)skb_put(nskb, sizeof(struct iphdr)); + niph->version = 4; + niph->ihl = sizeof(struct iphdr) / 4; + niph->tos = 0; + niph->id = 0; + niph->frag_off = htons(IP_DF); + niph->protocol = IPPROTO_TCP; + niph->check = 0; + niph->saddr = oiph->daddr; + niph->daddr = oiph->saddr; + + skb_reset_transport_header(nskb); + tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr)); + memset(tcph, 0, sizeof(*tcph)); + tcph->source = oth->dest; + tcph->dest = oth->source; + tcph->doff = sizeof(struct tcphdr) / 4; + + if (oth->ack) + tcph->seq = oth->ack_seq; + else { + tcph->ack_seq = htonl(ntohl(oth->seq) + oth->syn + oth->fin + + oldskb->len - ip_hdrlen(oldskb) - + (oth->doff << 2)); + tcph->ack = 1; + } + + tcph->rst = 1; + tcph->check = ~tcp_v4_check(sizeof(struct tcphdr), niph->saddr, + niph->daddr, 0); + nskb->ip_summed = CHECKSUM_PARTIAL; + nskb->csum_start = (unsigned char *)tcph - nskb->head; + nskb->csum_offset = offsetof(struct tcphdr, check); + + /* ip_route_me_harder expects skb->dst to be set */ + skb_dst_set_noref(nskb, skb_dst(oldskb)); + + nskb->protocol = htons(ETH_P_IP); + if (ip_route_me_harder(nskb, RTN_UNSPEC)) + goto free_nskb; + + niph->ttl = ip4_dst_hoplimit(skb_dst(nskb)); + + /* "Never happens" */ + if (nskb->len > dst_mtu(skb_dst(nskb))) + goto free_nskb; + + nf_ct_attach(nskb, oldskb); + +#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) + /* If we use ip_local_out for bridged traffic, the MAC source on + * the RST will be ours, instead of the destination's. This confuses + * some routers/firewalls, and they drop the packet. So we need to + * build the eth header using the original destination's MAC as the + * source, and send the RST packet directly. + */ + if (oldskb->nf_bridge) { + struct ethhdr *oeth = eth_hdr(oldskb); + nskb->dev = oldskb->nf_bridge->physindev; + niph->tot_len = htons(nskb->len); + ip_send_check(niph); + if (dev_hard_header(nskb, nskb->dev, ntohs(nskb->protocol), + oeth->h_source, oeth->h_dest, nskb->len) < 0) + goto free_nskb; + dev_queue_xmit(nskb); + } else +#endif + ip_local_out(nskb); + + return; + + free_nskb: + kfree_skb(nskb); +} +EXPORT_SYMBOL_GPL(nf_send_reset); diff --git a/net/ipv6/netfilter/Kconfig b/net/ipv6/netfilter/Kconfig index bb1a40db7be1..6af874fc187f 100644 --- a/net/ipv6/netfilter/Kconfig +++ b/net/ipv6/netfilter/Kconfig @@ -40,8 +40,13 @@ config NFT_CHAIN_ROUTE_IPV6 fields such as the source, destination, flowlabel, hop-limit and the packet mark. +config NF_REJECT_IPV6 + tristate "IPv6 packet rejection" + default m if NETFILTER_ADVANCED=n + config NFT_REJECT_IPV6 depends on NF_TABLES_IPV6 + select NF_REJECT_IPV6 default NFT_REJECT tristate @@ -208,6 +213,7 @@ config IP6_NF_FILTER config IP6_NF_TARGET_REJECT tristate "REJECT target support" depends on IP6_NF_FILTER + select NF_REJECT_IPV6 default m if NETFILTER_ADVANCED=n help The REJECT target allows a filtering rule to specify that an ICMPv6 diff --git a/net/ipv6/netfilter/Makefile b/net/ipv6/netfilter/Makefile index 0f7e5b3f328d..fbb25f01143c 100644 --- a/net/ipv6/netfilter/Makefile +++ b/net/ipv6/netfilter/Makefile @@ -27,6 +27,9 @@ obj-$(CONFIG_NF_DEFRAG_IPV6) += nf_defrag_ipv6.o # logging obj-$(CONFIG_NF_LOG_IPV6) += nf_log_ipv6.o +# reject +obj-$(CONFIG_NF_REJECT_IPV6) += nf_reject_ipv6.o + # nf_tables obj-$(CONFIG_NF_TABLES_IPV6) += nf_tables_ipv6.o obj-$(CONFIG_NFT_CHAIN_ROUTE_IPV6) += nft_chain_route_ipv6.o diff --git a/net/ipv6/netfilter/nf_reject_ipv6.c b/net/ipv6/netfilter/nf_reject_ipv6.c new file mode 100644 index 000000000000..5f5f0438d74d --- /dev/null +++ b/net/ipv6/netfilter/nf_reject_ipv6.c @@ -0,0 +1,163 @@ +/* (C) 1999-2001 Paul `Rusty' Russell + * (C) 2002-2004 Netfilter Core Team + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ +#include +#include +#include +#include +#include + +void nf_send_reset6(struct net *net, struct sk_buff *oldskb, int hook) +{ + struct sk_buff *nskb; + struct tcphdr otcph, *tcph; + unsigned int otcplen, hh_len; + int tcphoff, needs_ack; + const struct ipv6hdr *oip6h = ipv6_hdr(oldskb); + struct ipv6hdr *ip6h; +#define DEFAULT_TOS_VALUE 0x0U + const __u8 tclass = DEFAULT_TOS_VALUE; + struct dst_entry *dst = NULL; + u8 proto; + __be16 frag_off; + struct flowi6 fl6; + + if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) || + (!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) { + pr_debug("addr is not unicast.\n"); + return; + } + + proto = oip6h->nexthdr; + tcphoff = ipv6_skip_exthdr(oldskb, ((u8*)(oip6h+1) - oldskb->data), &proto, &frag_off); + + if ((tcphoff < 0) || (tcphoff > oldskb->len)) { + pr_debug("Cannot get TCP header.\n"); + return; + } + + otcplen = oldskb->len - tcphoff; + + /* IP header checks: fragment, too short. */ + if (proto != IPPROTO_TCP || otcplen < sizeof(struct tcphdr)) { + pr_debug("proto(%d) != IPPROTO_TCP, " + "or too short. otcplen = %d\n", + proto, otcplen); + return; + } + + if (skb_copy_bits(oldskb, tcphoff, &otcph, sizeof(struct tcphdr))) + BUG(); + + /* No RST for RST. */ + if (otcph.rst) { + pr_debug("RST is set\n"); + return; + } + + /* Check checksum. */ + if (nf_ip6_checksum(oldskb, hook, tcphoff, IPPROTO_TCP)) { + pr_debug("TCP checksum is invalid\n"); + return; + } + + memset(&fl6, 0, sizeof(fl6)); + fl6.flowi6_proto = IPPROTO_TCP; + fl6.saddr = oip6h->daddr; + fl6.daddr = oip6h->saddr; + fl6.fl6_sport = otcph.dest; + fl6.fl6_dport = otcph.source; + security_skb_classify_flow(oldskb, flowi6_to_flowi(&fl6)); + dst = ip6_route_output(net, NULL, &fl6); + if (dst == NULL || dst->error) { + dst_release(dst); + return; + } + dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0); + if (IS_ERR(dst)) + return; + + hh_len = (dst->dev->hard_header_len + 15)&~15; + nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr) + + sizeof(struct tcphdr) + dst->trailer_len, + GFP_ATOMIC); + + if (!nskb) { + net_dbg_ratelimited("cannot alloc skb\n"); + dst_release(dst); + return; + } + + skb_dst_set(nskb, dst); + + skb_reserve(nskb, hh_len + dst->header_len); + + skb_put(nskb, sizeof(struct ipv6hdr)); + skb_reset_network_header(nskb); + ip6h = ipv6_hdr(nskb); + ip6_flow_hdr(ip6h, tclass, 0); + ip6h->hop_limit = ip6_dst_hoplimit(dst); + ip6h->nexthdr = IPPROTO_TCP; + ip6h->saddr = oip6h->daddr; + ip6h->daddr = oip6h->saddr; + + skb_reset_transport_header(nskb); + tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr)); + /* Truncate to length (no data) */ + tcph->doff = sizeof(struct tcphdr)/4; + tcph->source = otcph.dest; + tcph->dest = otcph.source; + + if (otcph.ack) { + needs_ack = 0; + tcph->seq = otcph.ack_seq; + tcph->ack_seq = 0; + } else { + needs_ack = 1; + tcph->ack_seq = htonl(ntohl(otcph.seq) + otcph.syn + otcph.fin + + otcplen - (otcph.doff<<2)); + tcph->seq = 0; + } + + /* Reset flags */ + ((u_int8_t *)tcph)[13] = 0; + tcph->rst = 1; + tcph->ack = needs_ack; + tcph->window = 0; + tcph->urg_ptr = 0; + tcph->check = 0; + + /* Adjust TCP checksum */ + tcph->check = csum_ipv6_magic(&ipv6_hdr(nskb)->saddr, + &ipv6_hdr(nskb)->daddr, + sizeof(struct tcphdr), IPPROTO_TCP, + csum_partial(tcph, + sizeof(struct tcphdr), 0)); + + nf_ct_attach(nskb, oldskb); + +#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) + /* If we use ip6_local_out for bridged traffic, the MAC source on + * the RST will be ours, instead of the destination's. This confuses + * some routers/firewalls, and they drop the packet. So we need to + * build the eth header using the original destination's MAC as the + * source, and send the RST packet directly. + */ + if (oldskb->nf_bridge) { + struct ethhdr *oeth = eth_hdr(oldskb); + nskb->dev = oldskb->nf_bridge->physindev; + nskb->protocol = htons(ETH_P_IPV6); + ip6h->payload_len = htons(sizeof(struct tcphdr)); + if (dev_hard_header(nskb, nskb->dev, ntohs(nskb->protocol), + oeth->h_source, oeth->h_dest, nskb->len) < 0) + return; + dev_queue_xmit(nskb); + } else +#endif + ip6_local_out(nskb); +} +EXPORT_SYMBOL_GPL(nf_send_reset6); -- 2.20.1