--- /dev/null
+/*
+ * IPv4 specific functions of netfilter core
+ *
+ * Rusty Russell (C) 2000 -- This code is GPL.
+ * Patrick McHardy (C) 2006-2012
+ */
+#include <linux/kernel.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/ip.h>
+#include <linux/skbuff.h>
+#include <linux/gfp.h>
+#include <linux/export.h>
+#include <net/route.h>
+#include <net/xfrm.h>
+#include <net/ip.h>
+#include <net/netfilter/nf_queue.h>
+
+/* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
+int ip_route_me_harder(struct sk_buff *skb, unsigned int addr_type)
+{
+ struct net *net = dev_net(skb_dst(skb)->dev);
+ const struct iphdr *iph = ip_hdr(skb);
+ struct rtable *rt;
+ struct flowi4 fl4 = {};
+ __be32 saddr = iph->saddr;
+ __u8 flags = skb->sk ? inet_sk_flowi_flags(skb->sk) : 0;
+ unsigned int hh_len;
+
+ if (addr_type == RTN_UNSPEC)
+ addr_type = inet_addr_type(net, saddr);
+ if (addr_type == RTN_LOCAL || addr_type == RTN_UNICAST)
+ flags |= FLOWI_FLAG_ANYSRC;
+ else
+ saddr = 0;
+
+ /* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
+ * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook.
+ */
+ fl4.daddr = iph->daddr;
+ fl4.saddr = saddr;
+ fl4.flowi4_tos = RT_TOS(iph->tos);
+ fl4.flowi4_oif = skb->sk ? skb->sk->sk_bound_dev_if : 0;
+ fl4.flowi4_mark = skb->mark;
+ fl4.flowi4_flags = flags;
+ rt = ip_route_output_key(net, &fl4);
+ if (IS_ERR(rt))
+ return PTR_ERR(rt);
+
+ /* Drop old route. */
+ skb_dst_drop(skb);
+ skb_dst_set(skb, &rt->dst);
+
+ if (skb_dst(skb)->error)
+ return skb_dst(skb)->error;
+
+#ifdef CONFIG_XFRM
+ if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
+ xfrm_decode_session(skb, flowi4_to_flowi(&fl4), AF_INET) == 0) {
+ struct dst_entry *dst = skb_dst(skb);
+ skb_dst_set(skb, NULL);
+ dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), skb->sk, 0);
+ if (IS_ERR(dst))
+ return PTR_ERR(dst);
+ skb_dst_set(skb, dst);
+ }
+#endif
+
+ /* Change in oif may mean change in hh_len. */
+ hh_len = skb_dst(skb)->dev->hard_header_len;
+ if (skb_headroom(skb) < hh_len &&
+ pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),
+ 0, GFP_ATOMIC))
+ return -ENOMEM;
+
+ return 0;
+}
+EXPORT_SYMBOL(ip_route_me_harder);
+
+/*
+ * Extra routing may needed on local out, as the QUEUE target never
+ * returns control to the table.
+ */
+
+struct ip_rt_info {
+ __be32 daddr;
+ __be32 saddr;
+ u_int8_t tos;
+ u_int32_t mark;
+};
+
+static void nf_ip_saveroute(const struct sk_buff *skb,
+ struct nf_queue_entry *entry)
+{
+ struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
+
+ if (entry->state.hook == NF_INET_LOCAL_OUT) {
+ const struct iphdr *iph = ip_hdr(skb);
+
+ rt_info->tos = iph->tos;
+ rt_info->daddr = iph->daddr;
+ rt_info->saddr = iph->saddr;
+ rt_info->mark = skb->mark;
+ }
+}
+
+static int nf_ip_reroute(struct sk_buff *skb,
+ const struct nf_queue_entry *entry)
+{
+ const struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
+
+ if (entry->state.hook == NF_INET_LOCAL_OUT) {
+ const struct iphdr *iph = ip_hdr(skb);
+
+ if (!(iph->tos == rt_info->tos &&
+ skb->mark == rt_info->mark &&
+ iph->daddr == rt_info->daddr &&
+ iph->saddr == rt_info->saddr))
+ return ip_route_me_harder(skb, RTN_UNSPEC);
+ }
+ return 0;
+}
+
+__sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
+ unsigned int dataoff, u_int8_t protocol)
+{
+ const struct iphdr *iph = ip_hdr(skb);
+ __sum16 csum = 0;
+
+ switch (skb->ip_summed) {
+ case CHECKSUM_COMPLETE:
+ if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
+ break;
+ if ((protocol == 0 && !csum_fold(skb->csum)) ||
+ !csum_tcpudp_magic(iph->saddr, iph->daddr,
+ skb->len - dataoff, protocol,
+ skb->csum)) {
+ skb->ip_summed = CHECKSUM_UNNECESSARY;
+ break;
+ }
+ /* fall through */
+ case CHECKSUM_NONE:
+ if (protocol == 0)
+ skb->csum = 0;
+ else
+ skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
+ skb->len - dataoff,
+ protocol, 0);
+ csum = __skb_checksum_complete(skb);
+ }
+ return csum;
+}
+EXPORT_SYMBOL(nf_ip_checksum);
+
+static __sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook,
+ unsigned int dataoff, unsigned int len,
+ u_int8_t protocol)
+{
+ const struct iphdr *iph = ip_hdr(skb);
+ __sum16 csum = 0;
+
+ switch (skb->ip_summed) {
+ case CHECKSUM_COMPLETE:
+ if (len == skb->len - dataoff)
+ return nf_ip_checksum(skb, hook, dataoff, protocol);
+ /* fall through */
+ case CHECKSUM_NONE:
+ skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, protocol,
+ skb->len - dataoff, 0);
+ skb->ip_summed = CHECKSUM_NONE;
+ return __skb_checksum_complete_head(skb, dataoff + len);
+ }
+ return csum;
+}
+
+static int nf_ip_route(struct net *net, struct dst_entry **dst,
+ struct flowi *fl, bool strict __always_unused)
+{
+ struct rtable *rt = ip_route_output_key(net, &fl->u.ip4);
+ if (IS_ERR(rt))
+ return PTR_ERR(rt);
+ *dst = &rt->dst;
+ return 0;
+}
+
+static const struct nf_afinfo nf_ip_afinfo = {
+ .family = AF_INET,
+ .checksum = nf_ip_checksum,
+ .checksum_partial = nf_ip_checksum_partial,
+ .route = nf_ip_route,
+ .saveroute = nf_ip_saveroute,
+ .reroute = nf_ip_reroute,
+ .route_key_size = sizeof(struct ip_rt_info),
+};
+
+static int __init ipv4_netfilter_init(void)
+{
+ return nf_register_afinfo(&nf_ip_afinfo);
+}
+
+static void __exit ipv4_netfilter_fini(void)
+{
+ nf_unregister_afinfo(&nf_ip_afinfo);
+}
+
+module_init(ipv4_netfilter_init);
+module_exit(ipv4_netfilter_fini);
Code Review / kvmfornfv.git / blobdiff