[PATCH net] sctp: do not check port in sctp_inet6_cmp_addr

[Xin Long]

pf->cmp_addr() is called before binding a v6 address to the sock. It
should not check ports, like in sctp_inet_cmp_addr.

But sctp_inet6_cmp_addr checks the addr by invoking af(6)->cmp_addr,
sctp_v6_cmp_addr where it also compares the ports.

This would cause that setsockopt(SCTP_SOCKOPT_BINDX_ADD) could bind
multiple duplicated IPv6 addresses after Commit 40b4f0fd74e4 ("sctp:
lack the check for ports in sctp_v6_cmp_addr").

This patch is to remove af->cmp_addr called in sctp_inet6_cmp_addr,
but do the proper check for both v6 addrs and v4mapped addrs.

Fixes: 40b4f0fd74e4 ("sctp: lack the check for ports in sctp_v6_cmp_addr")
Reported-by: Jianwen Ji <j...@redhat.com>
Signed-off-by: Xin Long <lucien....@gmail.com>
---
 net/sctp/ipv6.c | 27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
index f1fc48e..be4b72c 100644
--- a/net/sctp/ipv6.c
+++ b/net/sctp/ipv6.c
@@ -846,8 +846,8 @@ static int sctp_inet6_cmp_addr(const union sctp_addr *addr1,
                               const union sctp_addr *addr2,
                               struct sctp_sock *opt)
 {
-       struct sctp_af *af1, *af2;
        struct sock *sk = sctp_opt2sk(opt);
+       struct sctp_af *af1, *af2;
 
        af1 = sctp_get_af_specific(addr1->sa.sa_family);
        af2 = sctp_get_af_specific(addr2->sa.sa_family);
@@ -863,10 +863,31 @@ static int sctp_inet6_cmp_addr(const union sctp_addr 
*addr1,
        if (sctp_is_any(sk, addr1) || sctp_is_any(sk, addr2))
                return 1;
 
-       if (addr1->sa.sa_family != addr2->sa.sa_family)
+       if (addr1->sa.sa_family != addr2->sa.sa_family) {
+               if (addr1->sa.sa_family == AF_INET &&
+                   addr2->sa.sa_family == AF_INET6 &&
+                   ipv6_addr_v4mapped(&addr2->v6.sin6_addr))
+                       if (addr2->v6.sin6_addr.s6_addr32[3] ==
+                           addr1->v4.sin_addr.s_addr)
+                               return 1;
+               if (addr2->sa.sa_family == AF_INET &&
+                   addr1->sa.sa_family == AF_INET6 &&
+                   ipv6_addr_v4mapped(&addr1->v6.sin6_addr))
+                       if (addr1->v6.sin6_addr.s6_addr32[3] ==
+                           addr2->v4.sin_addr.s_addr)
+                               return 1;
+               return 0;
+       }
+
+       if (!ipv6_addr_equal(&addr1->v6.sin6_addr, &addr2->v6.sin6_addr))
+               return 0;
+
+       if ((ipv6_addr_type(&addr1->v6.sin6_addr) & IPV6_ADDR_LINKLOCAL) &&
+           addr1->v6.sin6_scope_id && addr2->v6.sin6_scope_id &&
+           addr1->v6.sin6_scope_id != addr2->v6.sin6_scope_id)
                return 0;
 
-       return af1->cmp_addr(addr1, addr2);
+       return 1;
 }
 
 /* Verify that the provided sockaddr looks bindable.   Common verification,
-- 
2.1.0