> in the below test case, using the source address routing,
> sctp can not work.
> Node-A
> 1)ifconfig eth0 inet6 add 2001:1::1/64
> 2)ip -6 rule add from 2001:1::1 table 100 pref 100
> 3)ip -6 route add 2001:2::1 dev eth0 table 100
> 4)sctp_darn -H 2001:1::1 -P 250 -l &
> Node-B
> 1)ifconfig eth0 inet6 add 2001:2::1/64
> 2)ip -6 rule add from 2001:2::1 table 100 pref 100
> 3)ip -6 route add 2001:1::1 dev eth0 table 100
> 4)sctp_darn -H 2001:2::1 -P 250 -h 2001:1::1 -p 250 -s
>
> root cause:
> Node-A and Node-B use the source address routing, and
> at begining, source address will be NULL,sctp will
> search the routing table by the destination address,
> because using the source address routing table, and
> the result dst_entry will be NULL.
>
> solution:
> walk through the bind address list to get the source
> address and then lookup the routing table again to get
> the correct dst_entry.
>
> Signed-off-by: Weixing Shi <Weixing.Shi@xxxxxxxxxxxxx>
> ---
> net/sctp/ipv6.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
> 1 files changed, 62 insertions(+), 3 deletions(-)
>
> diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
> index 9fb5d37..5c55f98 100644
> --- a/net/sctp/ipv6.c
> +++ b/net/sctp/ipv6.c
> @@ -77,6 +77,10 @@
> #include <net/sctp/sctp.h>
>
> #include <asm/uaccess.h>
> +static void sctp_v6_dst_saddr(union sctp_addr *addr, struct dst_entry *dst,
> + __be16 port);
> +static int sctp_v6_cmp_addr(const union sctp_addr *addr1,
> + const union sctp_addr *addr2);
>
> /* Event handler for inet6 address addition/deletion events.
> * The sctp_local_addr_list needs to be protocted by a spin lock since
> @@ -242,8 +246,12 @@ static struct dst_entry *sctp_v6_get_dst(struct sctp_association *asoc,
> union sctp_addr *daddr,
> union sctp_addr *saddr)
> {
> - struct dst_entry *dst;
> - struct flowi fl;
> + struct dst_entry *dst = NULL;
> + struct flowi fl;
> + struct sctp_bind_addr *bp;
> + struct sctp_sockaddr_entry *laddr;
> + union sctp_addr dst_saddr;
> + sctp_scope_t scope;
>
> memset(&fl, 0, sizeof(fl));
> ipv6_addr_copy(&fl.fl6_dst, &daddr->v6.sin6_addr);
> @@ -259,7 +267,58 @@ static struct dst_entry *sctp_v6_get_dst(struct sctp_association *asoc,
> }
>
> dst = ip6_route_output(&init_net, NULL, &fl);
> - if (!dst->error) {
> + if (!asoc || saddr)
> + goto out;
> +
> + bp = &asoc->base.bind_addr;
> + scope = sctp_scope(daddr);
> +
> + if (dst) {
>
IIRC, this may always be true since dst should not be NULL.
If dst can be NULL, orig code will cause OOPS in if (!dst->error), right?
We should use if (!dst->error) to check whether dst is exists.
> + /* Walk through the bind address list and look for a bind
> + * address that matches the source address of the returned dst.
> + */
> + sctp_v6_dst_saddr(&dst_saddr, dst, htons(bp->port));
> + rcu_read_lock();
> + list_for_each_entry_rcu(laddr, &bp->address_list, list) {
> + if (!laddr->valid)
> + continue;
> + if ((laddr->state == SCTP_ADDR_SRC) &&
> + (laddr->a.sa.sa_family == AF_INET6) &&
> + (scope <= sctp_scope(&laddr->a)) &&
> + (sctp_v6_cmp_addr(&dst_saddr, &laddr->a))){
> + goto out_unlock;
> + }
> + rcu_read_unlock();
> +
> + /* None of the bound addresses match the source address of the
> + * dst. So release it.
> + */
> + dst_release(dst);
> + dst = NULL;
> + }
> + }
> +
> + /* Walk through the bind address list and try to get a dst that
> + * matches a bind address as the source address.
> + */
> + rcu_read_lock();
> + list_for_each_entry_rcu(laddr, &bp->address_list, list) {
> + if (!laddr->valid)
> + continue;
> + if ((laddr->state == SCTP_ADDR_SRC) &&
> + (laddr->a.sa.sa_family == AF_INET6) &&
> + (scope <= sctp_scope(&laddr->a))){
> + ipv6_addr_copy(&fl.fl6_src, &laddr->a.v6.sin6_addr);
> + dst = ip6_route_output(&init_net, NULL, &fl);
> + goto out_unlock;
> + }
> + }
> +
> +out_unlock:
> + rcu_read_unlock();
> +
> +out:
> + if (dst) {
> struct rt6_info *rt;
> rt = (struct rt6_info *)dst;
> SCTP_DEBUG_PRINTK("rt6_dst:%pI6 rt6_src:%pI6\n",
>
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