ipv6: Consolidate route lookup sequences.

Route lookups follow a general pattern in the ipv6 code wherein
we first find the non-IPSEC route, potentially override the
flow destination address due to ipv6 options settings, and then
finally make an IPSEC search using either xfrm_lookup() or
__xfrm_lookup().

__xfrm_lookup() is used when we want to generate a blackhole route
if the key manager needs to resolve the IPSEC rules (in this case
-EREMOTE is returned and the original 'dst' is left unchanged).

Otherwise plain xfrm_lookup() is used and when asynchronous IPSEC
resolution is necessary, we simply fail the lookup completely.

All of these cases are encapsulated into two routines,
ip6_dst_lookup_flow and ip6_sk_dst_lookup_flow.  The latter of which
handles unconnected UDP datagram sockets.

Signed-off-by: David S. Miller <davem@davemloft.net>

8 files changed, 114 insertions, 117 deletions

diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 3194aa909872..a88b2e9d25f1 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -644,9 +644,8 @@ EXPORT_SYMBOL(inet6_unregister_protosw);
 
 int inet6_sk_rebuild_header(struct sock *sk)
 {
-        int err;
-        struct dst_entry *dst;
         struct ipv6_pinfo *np = inet6_sk(sk);
+        struct dst_entry *dst;
 
         dst = __sk_dst_check(sk, np->dst_cookie);
 
@@ -668,17 +667,11 @@ int inet6_sk_rebuild_header(struct sock *sk)
 
                 final_p = fl6_update_dst(&fl, np->opt, &final);
 
-                err = ip6_dst_lookup(sk, &dst, &fl);
-                if (err) {
+                dst = ip6_dst_lookup_flow(sk, &fl, final_p, false);
+                if (IS_ERR(dst)) {
                         sk->sk_route_caps = 0;
-                        return err;
-                }
-                if (final_p)
-                        ipv6_addr_copy(&fl.fl6_dst, final_p);
-
-                if ((err = xfrm_lookup(sock_net(sk), &dst, &fl, sk, 0)) < 0) {
-                        sk->sk_err_soft = -err;
-                        return err;
+                        sk->sk_err_soft = -PTR_ERR(dst);
+                        return PTR_ERR(dst);
                 }
 
                 __ip6_dst_store(sk, dst, NULL, NULL);
diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
index 320bdb877eed..be3a781c0085 100644
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -162,18 +162,11 @@ ipv4_connected:
         opt = flowlabel ? flowlabel->opt : np->opt;
         final_p = fl6_update_dst(&fl, opt, &final);
 
-        err = ip6_dst_lookup(sk, &dst, &fl);
-        if (err)
+        dst = ip6_dst_lookup_flow(sk, &fl, final_p, true);
+        err = 0;
+        if (IS_ERR(dst)) {
+                err = PTR_ERR(dst);
                 goto out;
-        if (final_p)
-                ipv6_addr_copy(&fl.fl6_dst, final_p);
-
-        err = __xfrm_lookup(sock_net(sk), &dst, &fl, sk, XFRM_LOOKUP_WAIT);
-        if (err < 0) {
-                if (err == -EREMOTE)
-                        err = ip6_dst_blackhole(sk, &dst, &fl);
-                if (err < 0)
-                        goto out;
         }
 
         /* source address lookup done in ip6_dst_lookup */
diff --git a/net/ipv6/inet6_connection_sock.c b/net/ipv6/inet6_connection_sock.c
index d144e629d2b4..d687e1397333 100644
--- a/net/ipv6/inet6_connection_sock.c
+++ b/net/ipv6/inet6_connection_sock.c
@@ -74,13 +74,8 @@ struct dst_entry *inet6_csk_route_req(struct sock *sk,
         fl.fl_ip_sport = inet_rsk(req)->loc_port;
         security_req_classify_flow(req, &fl);
 
-        if (ip6_dst_lookup(sk, &dst, &fl))
-                return NULL;
-
-        if (final_p)
-                ipv6_addr_copy(&fl.fl6_dst, final_p);
-
-        if ((xfrm_lookup(sock_net(sk), &dst, &fl, sk, 0)) < 0)
+        dst = ip6_dst_lookup_flow(sk, &fl, final_p, false);
+        if (IS_ERR(dst))
                 return NULL;
 
         return dst;
@@ -234,21 +229,13 @@ int inet6_csk_xmit(struct sk_buff *skb)
         dst = __inet6_csk_dst_check(sk, np->dst_cookie);
 
         if (dst == NULL) {
-                int err = ip6_dst_lookup(sk, &dst, &fl);
-
-                if (err) {
-                        sk->sk_err_soft = -err;
-                        kfree_skb(skb);
-                        return err;
-                }
-
-                if (final_p)
-                        ipv6_addr_copy(&fl.fl6_dst, final_p);
+                dst = ip6_dst_lookup_flow(sk, &fl, final_p, false);
 
-                if ((err = xfrm_lookup(sock_net(sk), &dst, &fl, sk, 0)) < 0) {
+                if (IS_ERR(dst)) {
+                        sk->sk_err_soft = -PTR_ERR(dst);
                         sk->sk_route_caps = 0;
                         kfree_skb(skb);
-                        return err;
+                        return PTR_ERR(dst);
                 }
 
                 __inet6_csk_dst_store(sk, dst, NULL, NULL);
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 5c618f20523e..28209b2d254d 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1002,29 +1002,87 @@ int ip6_dst_lookup(struct sock *sk, struct dst_entry **dst, struct flowi *fl)
 EXPORT_SYMBOL_GPL(ip6_dst_lookup);
 
 /**
- *      ip6_sk_dst_lookup - perform socket cached route lookup on flow
+ *      ip6_dst_lookup_flow - perform route lookup on flow with ipsec
+ *      @sk: socket which provides route info
+ *      @fl: flow to lookup
+ *      @final_dst: final destination address for ipsec lookup
+ *      @want_blackhole: IPSEC blackhole handling desired
+ *
+ *      This function performs a route lookup on the given flow.
+ *
+ *      It returns a valid dst pointer on success, or a pointer encoded
+ *      error code.
+ */
+struct dst_entry *ip6_dst_lookup_flow(struct sock *sk, struct flowi *fl,
+                                      const struct in6_addr *final_dst,
+                                      bool want_blackhole)
+{
+        struct dst_entry *dst = NULL;
+        int err;
+
+        err = ip6_dst_lookup_tail(sk, &dst, fl);
+        if (err)
+                return ERR_PTR(err);
+        if (final_dst)
+                ipv6_addr_copy(&fl->fl6_dst, final_dst);
+        if (want_blackhole) {
+                err = __xfrm_lookup(sock_net(sk), &dst, fl, sk, XFRM_LOOKUP_WAIT);
+                if (err == -EREMOTE)
+                        err = ip6_dst_blackhole(sk, &dst, fl);
+                if (err)
+                        return ERR_PTR(err);
+        } else {
+                err = xfrm_lookup(sock_net(sk), &dst, fl, sk, 0);
+                if (err)
+                        return ERR_PTR(err);
+        }
+        return dst;
+}
+EXPORT_SYMBOL_GPL(ip6_dst_lookup_flow);
+
+/**
+ *      ip6_sk_dst_lookup_flow - perform socket cached route lookup on flow
  *      @sk: socket which provides the dst cache and route info
- *      @dst: pointer to dst_entry * for result
  *      @fl: flow to lookup
+ *      @final_dst: final destination address for ipsec lookup
+ *      @want_blackhole: IPSEC blackhole handling desired
  *
  *      This function performs a route lookup on the given flow with the
  *      possibility of using the cached route in the socket if it is valid.
  *      It will take the socket dst lock when operating on the dst cache.
  *      As a result, this function can only be used in process context.
  *
- *      It returns zero on success, or a standard errno code on error.
+ *      It returns a valid dst pointer on success, or a pointer encoded
+ *      error code.
  */
-int ip6_sk_dst_lookup(struct sock *sk, struct dst_entry **dst, struct flowi *fl)
+struct dst_entry *ip6_sk_dst_lookup_flow(struct sock *sk, struct flowi *fl,
+                                         const struct in6_addr *final_dst,
+                                         bool want_blackhole)
 {
-        *dst = NULL;
-        if (sk) {
-                *dst = sk_dst_check(sk, inet6_sk(sk)->dst_cookie);
-                *dst = ip6_sk_dst_check(sk, *dst, fl);
-        }
+        struct dst_entry *dst = sk_dst_check(sk, inet6_sk(sk)->dst_cookie);
+        int err;
 
-        return ip6_dst_lookup_tail(sk, dst, fl);
+        dst = ip6_sk_dst_check(sk, dst, fl);
+
+        err = ip6_dst_lookup_tail(sk, &dst, fl);
+        if (err)
+                return ERR_PTR(err);
+        if (final_dst)
+                ipv6_addr_copy(&fl->fl6_dst, final_dst);
+        if (want_blackhole) {
+                err = __xfrm_lookup(sock_net(sk), &dst, fl, sk, XFRM_LOOKUP_WAIT);
+                if (err == -EREMOTE)
+                        err = ip6_dst_blackhole(sk, &dst, fl);
+                if (err)
+                        return ERR_PTR(err);
+        } else {
+                err = xfrm_lookup(sock_net(sk), &dst, fl, sk, 0);
+                if (err)
+                        return ERR_PTR(err);
+        }
+        return dst;
 }
-EXPORT_SYMBOL_GPL(ip6_sk_dst_lookup);
+EXPORT_SYMBOL_GPL(ip6_sk_dst_lookup_flow);
 
 static inline int ip6_ufo_append_data(struct sock *sk,
                         int getfrag(void *from, char *to, int offset, int len,
diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index 364e86683388..dc29b07caf42 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -856,20 +856,11 @@ static int rawv6_sendmsg(struct kiocb *iocb, struct sock *sk,
                 fl.oif = np->mcast_oif;
         security_sk_classify_flow(sk, &fl);
 
-        err = ip6_dst_lookup(sk, &dst, &fl);
-        if (err)
+        dst = ip6_dst_lookup_flow(sk, &fl, final_p, true);
+        if (IS_ERR(dst)) {
+                err = PTR_ERR(dst);
                 goto out;
-        if (final_p)
-                ipv6_addr_copy(&fl.fl6_dst, final_p);
-
-        err = __xfrm_lookup(sock_net(sk), &dst, &fl, sk, XFRM_LOOKUP_WAIT);
-        if (err < 0) {
-                if (err == -EREMOTE)
-                        err = ip6_dst_blackhole(sk, &dst, &fl);
-                if (err < 0)
-                        goto out;
         }
-
         if (hlimit < 0) {
                 if (ipv6_addr_is_multicast(&fl.fl6_dst))
                         hlimit = np->mcast_hops;
diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index 09fd34f0dbf2..0b4cf350631b 100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -243,12 +243,9 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
                 fl.fl_ip_dport = inet_rsk(req)->rmt_port;
                 fl.fl_ip_sport = inet_sk(sk)->inet_sport;
                 security_req_classify_flow(req, &fl);
-                if (ip6_dst_lookup(sk, &dst, &fl))
-                        goto out_free;
 
-                if (final_p)
-                        ipv6_addr_copy(&fl.fl6_dst, final_p);
-                if ((xfrm_lookup(sock_net(sk), &dst, &fl, sk, 0)) < 0)
+                dst = ip6_dst_lookup_flow(sk, &fl, final_p, false);
+                if (IS_ERR(dst))
                         goto out_free;
         }
 
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 1d0ab5570904..e59a31c48baf 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -255,18 +255,10 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
 
         security_sk_classify_flow(sk, &fl);
 
-        err = ip6_dst_lookup(sk, &dst, &fl);
-        if (err)
+        dst = ip6_dst_lookup_flow(sk, &fl, final_p, true);
+        if (IS_ERR(dst)) {
+                err = PTR_ERR(dst);
                 goto failure;
-        if (final_p)
-                ipv6_addr_copy(&fl.fl6_dst, final_p);
-
-        err = __xfrm_lookup(sock_net(sk), &dst, &fl, sk, XFRM_LOOKUP_WAIT);
-        if (err < 0) {
-                if (err == -EREMOTE)
-                        err = ip6_dst_blackhole(sk, &dst, &fl);
-                if (err < 0)
-                        goto failure;
         }
 
         if (saddr == NULL) {
@@ -385,7 +377,7 @@ static void tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
         np = inet6_sk(sk);
 
         if (type == ICMPV6_PKT_TOOBIG) {
-                struct dst_entry *dst = NULL;
+                struct dst_entry *dst;
 
                 if (sock_owned_by_user(sk))
                         goto out;
@@ -413,13 +405,9 @@ static void tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
                         fl.fl_ip_sport = inet->inet_sport;
                         security_skb_classify_flow(skb, &fl);
 
-                        if ((err = ip6_dst_lookup(sk, &dst, &fl))) {
-                                sk->sk_err_soft = -err;
-                                goto out;
-                        }
-
-                        if ((err = xfrm_lookup(net, &dst, &fl, sk, 0)) < 0) {
-                                sk->sk_err_soft = -err;
+                        dst = ip6_dst_lookup_flow(sk, &fl, NULL, false);
+                        if (IS_ERR(dst)) {
+                                sk->sk_err_soft = -PTR_ERR(dst);
                                 goto out;
                         }
 
@@ -496,7 +484,7 @@ static int tcp_v6_send_synack(struct sock *sk, struct request_sock *req,
         struct in6_addr * final_p, final;
         struct flowi fl;
         struct dst_entry *dst;
-        int err = -1;
+        int err;
 
         memset(&fl, 0, sizeof(fl));
         fl.proto = IPPROTO_TCP;
@@ -512,15 +500,13 @@ static int tcp_v6_send_synack(struct sock *sk, struct request_sock *req,
         opt = np->opt;
         final_p = fl6_update_dst(&fl, opt, &final);
 
-        err = ip6_dst_lookup(sk, &dst, &fl);
-        if (err)
+        dst = ip6_dst_lookup_flow(sk, &fl, final_p, false);
+        if (IS_ERR(dst)) {
+                err = PTR_ERR(dst);
                 goto done;
-        if (final_p)
-                ipv6_addr_copy(&fl.fl6_dst, final_p);
-        if ((err = xfrm_lookup(sock_net(sk), &dst, &fl, sk, 0)) < 0)
-                goto done;
-
+        }
         skb = tcp_make_synack(sk, dst, req, rvp);
+        err = -ENOMEM;
         if (skb) {
                 __tcp_v6_send_check(skb, &treq->loc_addr, &treq->rmt_addr);
 
@@ -1079,15 +1065,14 @@ static void tcp_v6_send_response(struct sk_buff *skb, u32 seq, u32 ack, u32 win,
          * Underlying function will use this to retrieve the network
          * namespace
          */
-        if (!ip6_dst_lookup(ctl_sk, &dst, &fl)) {
-                if (xfrm_lookup(net, &dst, &fl, NULL, 0) >= 0) {
-                        skb_dst_set(buff, dst);
-                        ip6_xmit(ctl_sk, buff, &fl, NULL);
-                        TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
-                        if (rst)
-                                TCP_INC_STATS_BH(net, TCP_MIB_OUTRSTS);
-                        return;
-                }
+        dst = ip6_dst_lookup_flow(ctl_sk, &fl, NULL, false);
+        if (!IS_ERR(dst)) {
+                skb_dst_set(buff, dst);
+                ip6_xmit(ctl_sk, buff, &fl, NULL);
+                TCP_INC_STATS_BH(net, TCP_MIB_OUTSEGS);
+                if (rst)
+                        TCP_INC_STATS_BH(net, TCP_MIB_OUTRSTS);
+                return;
         }
 
         kfree_skb(buff);
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index a419a787eb69..d86d7f67a597 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1125,18 +1125,11 @@ do_udp_sendmsg:
 
         security_sk_classify_flow(sk, &fl);
 
-        err = ip6_sk_dst_lookup(sk, &dst, &fl);
-        if (err)
+        dst = ip6_sk_dst_lookup_flow(sk, &fl, final_p, true);
+        if (IS_ERR(dst)) {
+                err = PTR_ERR(dst);
+                dst = NULL;
                 goto out;
-        if (final_p)
-                ipv6_addr_copy(&fl.fl6_dst, final_p);
-
-        err = __xfrm_lookup(sock_net(sk), &dst, &fl, sk, XFRM_LOOKUP_WAIT);
-        if (err < 0) {
-                if (err == -EREMOTE)
-                        err = ip6_dst_blackhole(sk, &dst, &fl);
-                if (err < 0)
-                        goto out;
         }
 
         if (hlimit < 0) {