5 files changed, 49 insertions, 16 deletions

diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index 4b347c0ca094..1687b3de54ff 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -230,6 +230,7 @@ extern struct fib_table *fib_get_table(struct net *net, u32 id);
 /* Exported by fib_frontend.c */
 extern const struct nla_policy rtm_ipv4_policy[];
 extern void             ip_fib_init(void);
+extern __be32 fib_compute_spec_dst(struct sk_buff *skb);
 extern int fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
                                u8 tos, int oif, struct net_device *dev,
                                __be32 *spec_dst, u32 *itag);
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 3854411fa37c..451939b60c54 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -180,6 +180,35 @@ unsigned int inet_dev_addr_type(struct net *net, const struct net_device *dev,
 }
 EXPORT_SYMBOL(inet_dev_addr_type);
 
+__be32 fib_compute_spec_dst(struct sk_buff *skb)
+{
+        struct net_device *dev = skb->dev;
+        struct in_device *in_dev;
+        struct fib_result res;
+        struct flowi4 fl4;
+        struct net *net;
+
+        if (skb->pkt_type != PACKET_BROADCAST &&
+            skb->pkt_type != PACKET_MULTICAST)
+                return ip_hdr(skb)->daddr;
+
+        in_dev = __in_dev_get_rcu(dev);
+        BUG_ON(!in_dev);
+        fl4.flowi4_oif = 0;
+        fl4.flowi4_iif = 0;
+        fl4.daddr = ip_hdr(skb)->saddr;
+        fl4.saddr = ip_hdr(skb)->daddr;
+        fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
+        fl4.flowi4_scope = RT_SCOPE_UNIVERSE;
+        fl4.flowi4_mark = IN_DEV_SRC_VMARK(in_dev) ? skb->mark : 0;
+
+        net = dev_net(dev);
+        if (!fib_lookup(net, &fl4, &res))
+                return FIB_RES_PREFSRC(net, res);
+        else
+                return inet_select_addr(dev, 0, RT_SCOPE_UNIVERSE);
+}
+
 /* Given (packet source, input interface) and optional (dst, oif, tos):
  * - (main) check, that source is valid i.e. not broadcast or our local
  *   address.
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 49a74cc79dc8..4bce5a2830aa 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -95,6 +95,7 @@
 #include <net/checksum.h>
 #include <net/xfrm.h>
 #include <net/inet_common.h>
+#include <net/ip_fib.h>
 
 /*
  *      Build xmit assembly blocks
@@ -333,7 +334,7 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
         struct flowi4 fl4;
         struct sock *sk;
         struct inet_sock *inet;
-        __be32 daddr;
+        __be32 daddr, saddr;
 
         if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb))
                 return;
@@ -347,6 +348,7 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
 
         inet->tos = ip_hdr(skb)->tos;
         daddr = ipc.addr = ip_hdr(skb)->saddr;
+        saddr = fib_compute_spec_dst(skb);
         ipc.opt = NULL;
         ipc.tx_flags = 0;
         if (icmp_param->replyopts.opt.opt.optlen) {
@@ -356,7 +358,7 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
         }
         memset(&fl4, 0, sizeof(fl4));
         fl4.daddr = daddr;
-        fl4.saddr = rt->rt_spec_dst;
+        fl4.saddr = saddr;
         fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
         fl4.flowi4_proto = IPPROTO_ICMP;
         security_skb_classify_flow(skb, flowi4_to_flowi(&fl4));
diff --git a/net/ipv4/ip_options.c b/net/ipv4/ip_options.c
index 708b99494e23..766dfe56885a 100644
--- a/net/ipv4/ip_options.c
+++ b/net/ipv4/ip_options.c
@@ -27,6 +27,7 @@
 #include <net/icmp.h>
 #include <net/route.h>
 #include <net/cipso_ipv4.h>
+#include <net/ip_fib.h>
 
 /*
  * Write options to IP header, record destination address to
@@ -104,7 +105,7 @@ int ip_options_echo(struct ip_options *dopt, struct sk_buff *skb)
         sptr = skb_network_header(skb);
         dptr = dopt->__data;
 
-        daddr = skb_rtable(skb)->rt_spec_dst;
+        daddr = fib_compute_spec_dst(skb);
 
         if (sopt->rr) {
                 optlen  = sptr[sopt->rr+1];
@@ -250,15 +251,14 @@ void ip_options_fragment(struct sk_buff *skb)
 int ip_options_compile(struct net *net,
                        struct ip_options *opt, struct sk_buff *skb)
 {
-        int l;
-        unsigned char *iph;
-        unsigned char *optptr;
-        int optlen;
+        __be32 spec_dst = (__force __be32) 0;
         unsigned char *pp_ptr = NULL;
-        struct rtable *rt = NULL;
+        unsigned char *optptr;
+        unsigned char *iph;
+        int optlen, l;
 
         if (skb != NULL) {
-                rt = skb_rtable(skb);
+                spec_dst = fib_compute_spec_dst(skb);
                 optptr = (unsigned char *)&(ip_hdr(skb)[1]);
         } else
                 optptr = opt->__data;
@@ -330,8 +330,8 @@ int ip_options_compile(struct net *net,
                                         pp_ptr = optptr + 2;
                                         goto error;
                                 }
-                                if (rt) {
-                                        memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4);
+                                if (skb) {
+                                        memcpy(&optptr[optptr[2]-1], &spec_dst, 4);
                                         opt->is_changed = 1;
                                 }
                                 optptr[2] += 4;
@@ -372,8 +372,8 @@ int ip_options_compile(struct net *net,
                                                 goto error;
                                         }
                                         opt->ts = optptr - iph;
-                                        if (rt)  {
-                                                memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4);
+                                        if (skb)  {
+                                                memcpy(&optptr[optptr[2]-1], &spec_dst, 4);
                                                 timeptr = &optptr[optptr[2]+3];
                                         }
                                         opt->ts_needaddr = 1;
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 0d11f234d615..de29f46f68b0 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -40,6 +40,7 @@
 #if IS_ENABLED(CONFIG_IPV6)
 #include <net/transp_v6.h>
 #endif
+#include <net/ip_fib.h>
 
 #include <linux/errqueue.h>
 #include <asm/uaccess.h>
@@ -1019,8 +1020,8 @@ e_inval:
  * @sk: socket
  * @skb: buffer
  *
- * To support IP_CMSG_PKTINFO option, we store rt_iif and rt_spec_dst
- * in skb->cb[] before dst drop.
+ * To support IP_CMSG_PKTINFO option, we store rt_iif and specific
+ * destination in skb->cb[] before dst drop.
  * This way, receiver doesnt make cache line misses to read rtable.
  */
 void ipv4_pktinfo_prepare(struct sk_buff *skb)
@@ -1030,7 +1031,7 @@ void ipv4_pktinfo_prepare(struct sk_buff *skb)
 
         if (rt) {
                 pktinfo->ipi_ifindex = rt->rt_iif;
-                pktinfo->ipi_spec_dst.s_addr = rt->rt_spec_dst;
+                pktinfo->ipi_spec_dst.s_addr = fib_compute_spec_dst(skb);
         } else {
                 pktinfo->ipi_ifindex = 0;
                 pktinfo->ipi_spec_dst.s_addr = 0;