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>

1 files changed, 1 insertions, 117 deletions

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 <net/ip.h>
-#include <net/tcp.h>
-#include <net/route.h>
-#include <net/dst.h>
 #include <net/icmp.h>
 
 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 */