diff options
author | Paul Marks <pmarks@google.com> | 2012-12-03 10:26:54 +0000 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2012-12-03 15:34:47 -0500 |
commit | a5a81f0b9025867efb999d14a8dfc1907c5a4c3b (patch) | |
tree | 4b2de223b5e08e0dcd4604d3619c738ff45eb2d3 /net | |
parent | 5d097109257c03a71845729f8db6b5770c4bbedc (diff) | |
download | linux-a5a81f0b9025867efb999d14a8dfc1907c5a4c3b.tar.bz2 |
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')
-rw-r--r-- | net/ipv6/route.c | 24 |
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; } |