Commit dbc2b5e9 authored by Xin Long's avatar Xin Long Committed by David S. Miller

sctp: fix src address selection if using secondary addresses for ipv6

Commit 0ca50d12 ("sctp: fix src address selection if using secondary
addresses") has fixed a src address selection issue when using secondary
addresses for ipv4.

Now sctp ipv6 also has the similar issue. When using a secondary address,
sctp_v6_get_dst tries to choose the saddr which has the most same bits
with the daddr by sctp_v6_addr_match_len. It may make some cases not work
as expected.

  [1] fd21:356b:459a:cf10::11 (eth1)
  [2] fd21:356b:459a:cf20::11 (eth2)

  [a] fd21:356b:459a:cf30::2  (eth1)
  [b] fd21:356b:459a:cf40::2  (eth2)

route from hostA to hostB:
  fd21:356b:459a:cf30::/64 dev eth1  metric 1024  mtu 1500

The expected path should be:
  fd21:356b:459a:cf10::11 <-> fd21:356b:459a:cf30::2
But addr[2] matches addr[a] more bits than addr[1] does, according to
sctp_v6_addr_match_len. It causes the path to be:
  fd21:356b:459a:cf20::11 <-> fd21:356b:459a:cf30::2

This patch is to fix it with the same way as Marcelo's fix for sctp ipv4.
As no ip_dev_find for ipv6, this patch is to use ipv6_chk_addr to check
if the saddr is in a dev instead.

Note that for backwards compatibility, it will still do the addr_match_len
check here when no optimal is found.
Reported-by: default avatarPatrick Talbert <>
Signed-off-by: default avatarXin Long <>
Signed-off-by: default avatarDavid S. Miller <>
parent df0c8d91
......@@ -240,12 +240,10 @@ static void sctp_v6_get_dst(struct sctp_transport *t, union sctp_addr *saddr,
struct sctp_bind_addr *bp;
struct ipv6_pinfo *np = inet6_sk(sk);
struct sctp_sockaddr_entry *laddr;
union sctp_addr *baddr = NULL;
union sctp_addr *daddr = &t->ipaddr;
union sctp_addr dst_saddr;
struct in6_addr *final_p, final;
__u8 matchlen = 0;
__u8 bmatchlen;
sctp_scope_t scope;
memset(fl6, 0, sizeof(struct flowi6));
......@@ -312,23 +310,37 @@ static void sctp_v6_get_dst(struct sctp_transport *t, union sctp_addr *saddr,
list_for_each_entry_rcu(laddr, &bp->address_list, list) {
if (!laddr->valid)
struct dst_entry *bdst;
__u8 bmatchlen;
if (!laddr->valid ||
laddr->state != SCTP_ADDR_SRC ||
laddr-> != AF_INET6 ||
scope > sctp_scope(&laddr->a))
if ((laddr->state == SCTP_ADDR_SRC) &&
(laddr-> == AF_INET6) &&
(scope <= sctp_scope(&laddr->a))) {
bmatchlen = sctp_v6_addr_match_len(daddr, &laddr->a);
if (!baddr || (matchlen < bmatchlen)) {
baddr = &laddr->a;
matchlen = bmatchlen;
if (baddr) {
fl6->saddr = baddr->v6.sin6_addr;
fl6->fl6_sport = baddr->v6.sin6_port;
fl6->saddr = laddr->a.v6.sin6_addr;
fl6->fl6_sport = laddr->a.v6.sin6_port;
final_p = fl6_update_dst(fl6, rcu_dereference(np->opt), &final);
dst = ip6_dst_lookup_flow(sk, fl6, final_p);
bdst = ip6_dst_lookup_flow(sk, fl6, final_p);
if (!IS_ERR(bdst) &&
&laddr->a.v6.sin6_addr, bdst->dev, 1)) {
if (!IS_ERR_OR_NULL(dst))
dst = bdst;
bmatchlen = sctp_v6_addr_match_len(daddr, &laddr->a);
if (matchlen > bmatchlen)
if (!IS_ERR_OR_NULL(dst))
dst = bdst;
matchlen = bmatchlen;
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