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authorPablo Neira Ayuso <pablo@netfilter.org>2014-09-26 14:35:15 +0200
committerPablo Neira Ayuso <pablo@netfilter.org>2014-10-02 18:30:49 +0200
commitc8d7b98bec43faaa6583c3135030be5eb4693acb (patch)
treef7a8eaf696632ec402b61bbefd534d66d2b48c33 /net/ipv4
parent51b0a5d8c21a91801bbef9bcc8639dc0b206c6cd (diff)
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 <pablo@netfilter.org>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/netfilter/Kconfig6
-rw-r--r--net/ipv4/netfilter/Makefile3
-rw-r--r--net/ipv4/netfilter/nf_reject_ipv4.c127
3 files changed, 136 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/Kconfig b/net/ipv4/netfilter/Kconfig
index 345242a79db..4c019d5c3f5 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 14488cc5fd2..f4cef5af096 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 00000000000..b023b4eb1a9
--- /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 <coreteam@netfilter.org>
+ *
+ * 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 <net/ip.h>
+#include <net/tcp.h>
+#include <net/route.h>
+#include <net/dst.h>
+#include <linux/netfilter_ipv4.h>
+
+/* 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);