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[IPV6]: ROUTE: Ensure to accept redirects from nexthop for the target.

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It is possible to get redirects from nexthop of "more-specific"
routes.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
YOSHIFUJI Hideaki 2006-03-20 17:07:49 -08:00 committed by David S. Miller
parent 09c884d4c3
commit e843b9e1be
1 changed files with 47 additions and 43 deletions
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90
net/ipv6/route.c
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@ -1144,59 +1144,63 @@ static int ip6_route_del(struct in6_rtmsg *rtmsg, struct nlmsghdr *nlh, void *_r
void rt6_redirect(struct in6_addr *dest, struct in6_addr *saddr,
struct neighbour *neigh, u8 *lladdr, int on_link)
{
struct rt6_info *rt, *nrt;
/* Locate old route to this destination. */
rt = rt6_lookup(dest, NULL, neigh->dev->ifindex, 1);
if (rt == NULL)
return;
if (neigh->dev != rt->rt6i_dev)
goto out;
struct rt6_info *rt, *nrt = NULL;
int strict;
struct fib6_node *fn;
/*
* Current route is on-link; redirect is always invalid.
*
* Seems, previous statement is not true. It could
* be node, which looks for us as on-link (f.e. proxy ndisc)
* But then router serving it might decide, that we should
* know truth 8)8) --ANK (980726).
* Get the "current" route for this destination and
* check if the redirect has come from approriate router.
*
* RFC 2461 specifies that redirects should only be
* accepted if they come from the nexthop to the target.
* Due to the way the routes are chosen, this notion
* is a bit fuzzy and one might need to check all possible
* routes.
*/
if (!(rt->rt6i_flags&RTF_GATEWAY))
goto out;
strict = ipv6_addr_type(dest) & (IPV6_ADDR_MULTICAST | IPV6_ADDR_LINKLOCAL);
/*
* RFC 2461 specifies that redirects should only be
* accepted if they come from the nexthop to the target.
* Due to the way default routers are chosen, this notion
* is a bit fuzzy and one might need to check all default
* routers.
*/
if (!ipv6_addr_equal(saddr, &rt->rt6i_gateway)) {
if (rt->rt6i_flags & RTF_DEFAULT) {
struct rt6_info *rt1;
read_lock(&rt6_lock);
for (rt1 = ip6_routing_table.leaf; rt1; rt1 = rt1->u.next) {
if (ipv6_addr_equal(saddr, &rt1->rt6i_gateway)) {
dst_hold(&rt1->u.dst);
dst_release(&rt->u.dst);
read_unlock(&rt6_lock);
rt = rt1;
goto source_ok;
}
}
read_unlock(&rt6_lock);
read_lock_bh(&rt6_lock);
fn = fib6_lookup(&ip6_routing_table, dest, NULL);
restart:
for (rt = fn->leaf; rt; rt = rt->u.next) {
/*
* Current route is on-link; redirect is always invalid.
*
* Seems, previous statement is not true. It could
* be node, which looks for us as on-link (f.e. proxy ndisc)
* But then router serving it might decide, that we should
* know truth 8)8) --ANK (980726).
*/
if (rt6_check_expired(rt))
continue;
if (!(rt->rt6i_flags & RTF_GATEWAY))
continue;
if (neigh->dev != rt->rt6i_dev)
continue;
if (!ipv6_addr_equal(saddr, &rt->rt6i_gateway))
continue;
break;
}
if (rt)
dst_hold(&rt->u.dst);
else if (strict) {
while ((fn = fn->parent) != NULL) {
if (fn->fn_flags & RTN_ROOT)
break;
if (fn->fn_flags & RTN_RTINFO)
goto restart;
}
}
read_unlock_bh(&rt6_lock);
if (!rt) {
if (net_ratelimit())
printk(KERN_DEBUG "rt6_redirect: source isn't a valid nexthop "
"for redirect target\n");
goto out;
return;
}
source_ok:
/*
* We have finally decided to accept it.
*/