net: ipv6: Fix ping to link-local addresses.

ping_v6_sendmsg does not set flowi6_oif in response to
sin6_scope_id or sk_bound_dev_if, so it is not possible to use
these APIs to ping an IPv6 address on a different interface.
Instead, it sets flowi6_iif, which is incorrect but harmless.

Stop setting flowi6_iif, and support various ways of setting oif
in the same priority order used by udpv6_sendmsg.

Tested: https://android-review.googlesource.com/#/c/254470/
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/ping.c b/net/ipv6/ping.c
index fed40d1ec29b1fc331ad04b5a7173b183a116279..0900352c924c163b4e0d945a5a30699628b5abfb 100644 (file)
--- a/net/ipv6/ping.c
+++ b/net/ipv6/ping.c
@@ -55,7 +55,7 @@ static int ping_v6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
        struct icmp6hdr user_icmph;
        int addr_type;
        struct in6_addr *daddr;
-       int iif = 0;
+       int oif = 0;
        struct flowi6 fl6;
        int err;
        struct dst_entry *dst;
@@ -78,25 +78,30 @@ static int ping_v6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
                if (u->sin6_family != AF_INET6) {
                        return -EAFNOSUPPORT;
                }
-               if (sk->sk_bound_dev_if &&
-                   sk->sk_bound_dev_if != u->sin6_scope_id) {
-                       return -EINVAL;
-               }
                daddr = &(u->sin6_addr);
-               iif = u->sin6_scope_id;
+               if (__ipv6_addr_needs_scope_id(ipv6_addr_type(daddr)))
+                       oif = u->sin6_scope_id;
        } else {
                if (sk->sk_state != TCP_ESTABLISHED)
                        return -EDESTADDRREQ;
                daddr = &sk->sk_v6_daddr;
        }
 
-       if (!iif)
-               iif = sk->sk_bound_dev_if;
+       if (!oif)
+               oif = sk->sk_bound_dev_if;
+
+       if (!oif)
+               oif = np->sticky_pktinfo.ipi6_ifindex;
+
+       if (!oif && ipv6_addr_is_multicast(daddr))
+               oif = np->mcast_oif;
+       else if (!oif)
+               oif = np->ucast_oif;
 
        addr_type = ipv6_addr_type(daddr);
-       if (__ipv6_addr_needs_scope_id(addr_type) && !iif)
-               return -EINVAL;
-       if (addr_type & IPV6_ADDR_MAPPED)
+       if ((__ipv6_addr_needs_scope_id(addr_type) && !oif) ||
+           (addr_type & IPV6_ADDR_MAPPED) ||
+           (oif && sk->sk_bound_dev_if && oif != sk->sk_bound_dev_if))
                return -EINVAL;
 
        /* TODO: use ip6_datagram_send_ctl to get options from cmsg */
@@ -106,16 +111,12 @@ static int ping_v6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
        fl6.flowi6_proto = IPPROTO_ICMPV6;
        fl6.saddr = np->saddr;
        fl6.daddr = *daddr;
+       fl6.flowi6_oif = oif;
        fl6.flowi6_mark = sk->sk_mark;
        fl6.fl6_icmp_type = user_icmph.icmp6_type;
        fl6.fl6_icmp_code = user_icmph.icmp6_code;
        security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));
 
-       if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
-               fl6.flowi6_oif = np->mcast_oif;
-       else if (!fl6.flowi6_oif)
-               fl6.flowi6_oif = np->ucast_oif;
-
        ipc6.tclass = np->tclass;
        fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel);