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authorPaul Marks <pmarks@google.com>2012-12-03 10:26:54 +0000
committerDavid S. Miller <davem@davemloft.net>2012-12-03 15:34:47 -0500
commita5a81f0b9025867efb999d14a8dfc1907c5a4c3b (patch)
tree4b2de223b5e08e0dcd4604d3619c738ff45eb2d3 /net/ipv6
parent5d097109257c03a71845729f8db6b5770c4bbedc (diff)
ipv6: Fix default route failover when CONFIG_IPV6_ROUTER_PREF=n
I believe this commit from 2008 was incorrect: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=398bcbebb6f721ac308df1e3d658c0029bb74503 When CONFIG_IPV6_ROUTER_PREF is disabled, the kernel should follow RFC4861 section 6.3.6: if no route is NUD_VALID, then traffic should be sprayed across all routers (indirectly triggering NUD) until one of them becomes NUD_VALID. However, the following experiment demonstrates that this does not work: 1) Connect to an IPv6 network. 2) Change the router's MAC (and link-local) address. The kernel will lock onto the first router and never try the new one, even if the first becomes unreachable. This patch fixes the problem by allowing rt6_check_neigh() to return 0; if all routers return 0, then rt6_select() will fall back to round-robin behavior. This patch should have no effect when CONFIG_IPV6_ROUTER_PREF=y. Note that rt6_check_neigh() is only used in a boolean context, so I've changed its return type accordingly. Signed-off-by: Paul Marks <pmarks@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6')
-rw-r--r--net/ipv6/route.c24
1 files changed, 10 insertions, 14 deletions
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 8f124f575116..e229a3bc345d 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -544,35 +544,32 @@ static inline int rt6_check_dev(struct rt6_info *rt, int oif)
return 0;
}
-static inline int rt6_check_neigh(struct rt6_info *rt)
+static inline bool rt6_check_neigh(struct rt6_info *rt)
{
struct neighbour *neigh;
- int m;
+ bool ret = false;
neigh = rt->n;
if (rt->rt6i_flags & RTF_NONEXTHOP ||
!(rt->rt6i_flags & RTF_GATEWAY))
- m = 1;
+ ret = true;
else if (neigh) {
read_lock_bh(&neigh->lock);
if (neigh->nud_state & NUD_VALID)
- m = 2;
+ ret = true;
#ifdef CONFIG_IPV6_ROUTER_PREF
- else if (neigh->nud_state & NUD_FAILED)
- m = 0;
+ else if (!(neigh->nud_state & NUD_FAILED))
+ ret = true;
#endif
- else
- m = 1;
read_unlock_bh(&neigh->lock);
- } else
- m = 0;
- return m;
+ }
+ return ret;
}
static int rt6_score_route(struct rt6_info *rt, int oif,
int strict)
{
- int m, n;
+ int m;
m = rt6_check_dev(rt, oif);
if (!m && (strict & RT6_LOOKUP_F_IFACE))
@@ -580,8 +577,7 @@ static int rt6_score_route(struct rt6_info *rt, int oif,
#ifdef CONFIG_IPV6_ROUTER_PREF
m |= IPV6_DECODE_PREF(IPV6_EXTRACT_PREF(rt->rt6i_flags)) << 2;
#endif
- n = rt6_check_neigh(rt);
- if (!n && (strict & RT6_LOOKUP_F_REACHABLE))
+ if (!rt6_check_neigh(rt) && (strict & RT6_LOOKUP_F_REACHABLE))
return -1;
return m;
}