4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xin Long <lucien.xin@xxxxxxxxx> [ Upstream commit dbc2b5e9a09e9a6664679a667ff81cff6e5f2641 ] Commit 0ca50d12fe46 ("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. hostA: [1] fd21:356b:459a:cf10::11 (eth1) [2] fd21:356b:459a:cf20::11 (eth2) hostB: [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: Patrick Talbert <ptalbert@xxxxxxxxxx> Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/sctp/ipv6.c | 46 +++++++++++++++++++++++++++++----------------- 1 file changed, 29 insertions(+), 17 deletions(-) --- a/net/sctp/ipv6.c +++ b/net/sctp/ipv6.c @@ -240,12 +240,10 @@ static void sctp_v6_get_dst(struct sctp_ 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_ */ rcu_read_lock(); 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->a.sa.sa_family != AF_INET6 || + scope > sctp_scope(&laddr->a)) continue; - if ((laddr->state == SCTP_ADDR_SRC) && - (laddr->a.sa.sa_family == 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) && + ipv6_chk_addr(dev_net(bdst->dev), + &laddr->a.v6.sin6_addr, bdst->dev, 1)) { + if (!IS_ERR_OR_NULL(dst)) + dst_release(dst); + dst = bdst; + break; + } + + bmatchlen = sctp_v6_addr_match_len(daddr, &laddr->a); + if (matchlen > bmatchlen) + continue; + + if (!IS_ERR_OR_NULL(dst)) + dst_release(dst); + dst = bdst; + matchlen = bmatchlen; } rcu_read_unlock();