net: Propagate lookup failure in l3mdev_get_saddr to caller

Commands run in a vrf context are not failing as expected on a route lookup:
    root@kenny:~# ip ro ls table vrf-red
    unreachable default

    root@kenny:~# ping -I vrf-red -c1 -w1 10.100.1.254
    ping: Warning: source address might be selected on device other than vrf-red.
    PING 10.100.1.254 (10.100.1.254) from 0.0.0.0 vrf-red: 56(84) bytes of data.

    --- 10.100.1.254 ping statistics ---
    2 packets transmitted, 0 received, 100% packet loss, time 999ms

Since the vrf table does not have a route for 10.100.1.254 the ping
should have failed. The saddr lookup causes a full VRF table lookup.
Propogating a lookup failure to the user allows the command to fail as
expected:

    root@kenny:~# ping -I vrf-red -c1 -w1 10.100.1.254
    connect: No route to host

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c
index 4f97484..0a242b2 100644 (file)
--- a/drivers/net/vrf.c
+++ b/drivers/net/vrf.c
@@ -800,7 +800,7 @@ static struct rtable *vrf_get_rtable(const struct net_device *dev,
 }
 
 /* called under rcu_read_lock */
-static void vrf_get_saddr(struct net_device *dev, struct flowi4 *fl4)
+static int vrf_get_saddr(struct net_device *dev, struct flowi4 *fl4)
 {
        struct fib_result res = { .tclassid = 0 };
        struct net *net = dev_net(dev);
@@ -808,9 +808,10 @@ static void vrf_get_saddr(struct net_device *dev, struct flowi4 *fl4)
        u8 flags = fl4->flowi4_flags;
        u8 scope = fl4->flowi4_scope;
        u8 tos = RT_FL_TOS(fl4);
+       int rc;
 
        if (unlikely(!fl4->daddr))
-               return;
+               return 0;
 
        fl4->flowi4_flags |= FLOWI_FLAG_SKIP_NH_OIF;
        fl4->flowi4_iif = LOOPBACK_IFINDEX;
@@ -818,7 +819,8 @@ static void vrf_get_saddr(struct net_device *dev, struct flowi4 *fl4)
        fl4->flowi4_scope = ((tos & RTO_ONLINK) ?
                             RT_SCOPE_LINK : RT_SCOPE_UNIVERSE);
 
-       if (!fib_lookup(net, fl4, &res, 0)) {
+       rc = fib_lookup(net, fl4, &res, 0);
+       if (!rc) {
                if (res.type == RTN_LOCAL)
                        fl4->saddr = res.fi->fib_prefsrc ? : fl4->daddr;
                else
@@ -828,6 +830,8 @@ static void vrf_get_saddr(struct net_device *dev, struct flowi4 *fl4)
        fl4->flowi4_flags = flags;
        fl4->flowi4_tos = orig_tos;
        fl4->flowi4_scope = scope;
+
+       return rc;
 }
 
 #if IS_ENABLED(CONFIG_IPV6)

diff --git a/include/net/l3mdev.h b/include/net/l3mdev.h
index 774d85b..5689a0c 100644 (file)
--- a/include/net/l3mdev.h
+++ b/include/net/l3mdev.h
@@ -29,7 +29,7 @@ struct l3mdev_ops {
        /* IPv4 ops */
        struct rtable * (*l3mdev_get_rtable)(const struct net_device *dev,
                                             const struct flowi4 *fl4);
-       void            (*l3mdev_get_saddr)(struct net_device *dev,
+       int             (*l3mdev_get_saddr)(struct net_device *dev,
                                            struct flowi4 *fl4);
 
        /* IPv6 ops */
@@ -112,10 +112,11 @@ static inline bool netif_index_is_l3_master(struct net *net, int ifindex)
        return rc;
 }
 
-static inline void l3mdev_get_saddr(struct net *net, int ifindex,
-                                   struct flowi4 *fl4)
+static inline int l3mdev_get_saddr(struct net *net, int ifindex,
+                                  struct flowi4 *fl4)
 {
        struct net_device *dev;
+       int rc = 0;
 
        if (ifindex) {
 
@@ -124,11 +125,13 @@ static inline void l3mdev_get_saddr(struct net *net, int ifindex,
                dev = dev_get_by_index_rcu(net, ifindex);
                if (dev && netif_is_l3_master(dev) &&
                    dev->l3mdev_ops->l3mdev_get_saddr) {
-                       dev->l3mdev_ops->l3mdev_get_saddr(dev, fl4);
+                       rc = dev->l3mdev_ops->l3mdev_get_saddr(dev, fl4);
                }
 
                rcu_read_unlock();
        }
+
+       return rc;
 }
 
 static inline struct dst_entry *l3mdev_get_rt6_dst(const struct net_device *dev,
@@ -200,9 +203,10 @@ static inline bool netif_index_is_l3_master(struct net *net, int ifindex)
        return false;
 }
 
-static inline void l3mdev_get_saddr(struct net *net, int ifindex,
-                                   struct flowi4 *fl4)
+static inline int l3mdev_get_saddr(struct net *net, int ifindex,
+                                  struct flowi4 *fl4)
 {
+       return 0;
 }
 
 static inline

diff --git a/include/net/route.h b/include/net/route.h
index ee81307..a3b9ef7 100644 (file)
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -283,7 +283,12 @@ static inline struct rtable *ip_route_connect(struct flowi4 *fl4,
                              sport, dport, sk);
 
        if (!src && oif) {
-               l3mdev_get_saddr(net, oif, fl4);
+               int rc;
+
+               rc = l3mdev_get_saddr(net, oif, fl4);
+               if (rc < 0)
+                       return ERR_PTR(rc);
+
                src = fl4->saddr;
        }
        if (!dst || !src) {

diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 63e5be0..bc35f18 100644 (file)
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -601,8 +601,11 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
                            (inet->hdrincl ? FLOWI_FLAG_KNOWN_NH : 0),
                           daddr, saddr, 0, 0);
 
-       if (!saddr && ipc.oif)
-               l3mdev_get_saddr(net, ipc.oif, &fl4);
+       if (!saddr && ipc.oif) {
+               err = l3mdev_get_saddr(net, ipc.oif, &fl4);
+               if (err < 0)
+                       goto done;
+       }
 
        if (!inet->hdrincl) {
                rfv.msg = msg;

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 0c7b0e6..c438908 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1025,8 +1025,11 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
                                   flow_flags,
                                   faddr, saddr, dport, inet->inet_sport);
 
-               if (!saddr && ipc.oif)
-                       l3mdev_get_saddr(net, ipc.oif, fl4);
+               if (!saddr && ipc.oif) {
+                       err = l3mdev_get_saddr(net, ipc.oif, fl4);
+                       if (err < 0)
+                               goto out;
+               }
 
                security_sk_classify_flow(sk, flowi4_to_flowi(fl4));
                rt = ip_route_output_flow(net, fl4, sk);