3.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
[ Upstream commit afc154e978de1eb11c555bc8bcec1552f75ebc43 ]
This is a follow-up patch to 3630d40067a21d4dfbadc6002bb469ce26ac5d52
("ipv6: rt6_check_neigh should successfully verify neigh if no NUD
information are available").
Since the removal of rt->n in rt6_info we can end up with a dst ==
NULL in rt6_check_neigh. In case the kernel is not compiled with
CONFIG_IPV6_ROUTER_PREF we should also select a route with unkown
NUD state but we must not avoid doing round robin selection on routes
with the same target. So introduce and pass down a boolean ``do_rr'' to
indicate when we should update rt->rr_ptr. As soon as no route is valid
we do backtracking and do a lookup on a higher level in the fib trie.
v2:
a) Improved rt6_check_neigh logic (no need to create neighbour there)
and documented return values.
v3:
a) Introduce enum rt6_nud_state to get rid of the magic numbers
(thanks to David Miller).
b) Update and shorten commit message a bit to actualy reflect
the source.
Reported-by: Pierre Emeriaud <petrus.lt@xxxxxxxxx>
Cc: YOSHIFUJI Hideaki <yoshfuji@xxxxxxxxxxxxxx>
Signed-off-by: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv6/route.c | 63 ++++++++++++++++++++++++++++++++++---------------------
1 file changed, 40 insertions(+), 23 deletions(-)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -65,6 +65,12 @@
#include <linux/sysctl.h>
#endif
+enum rt6_nud_state {
+ RT6_NUD_FAIL_HARD = -2,
+ RT6_NUD_FAIL_SOFT = -1,
+ RT6_NUD_SUCCEED = 1
+};
+
static struct rt6_info *ip6_rt_copy(struct rt6_info *ort,
const struct in6_addr *dest);
static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie);
@@ -527,28 +533,29 @@ static inline int rt6_check_dev(struct r
return 0;
}
-static inline bool rt6_check_neigh(struct rt6_info *rt)
+static inline enum rt6_nud_state rt6_check_neigh(struct rt6_info *rt)
{
struct neighbour *neigh;
- bool ret = false;
+ enum rt6_nud_state ret = RT6_NUD_FAIL_HARD;
if (rt->rt6i_flags & RTF_NONEXTHOP ||
!(rt->rt6i_flags & RTF_GATEWAY))
- return true;
+ return RT6_NUD_SUCCEED;
rcu_read_lock_bh();
neigh = __ipv6_neigh_lookup_noref(rt->dst.dev, &rt->rt6i_gateway);
if (neigh) {
read_lock(&neigh->lock);
if (neigh->nud_state & NUD_VALID)
- ret = true;
+ ret = RT6_NUD_SUCCEED;
#ifdef CONFIG_IPV6_ROUTER_PREF
else if (!(neigh->nud_state & NUD_FAILED))
- ret = true;
+ ret = RT6_NUD_SUCCEED;
#endif
read_unlock(&neigh->lock);
- } else if (IS_ENABLED(CONFIG_IPV6_ROUTER_PREF)) {
- ret = true;
+ } else {
+ ret = IS_ENABLED(CONFIG_IPV6_ROUTER_PREF) ?
+ RT6_NUD_SUCCEED : RT6_NUD_FAIL_SOFT;
}
rcu_read_unlock_bh();
@@ -562,43 +569,52 @@ static int rt6_score_route(struct rt6_in
m = rt6_check_dev(rt, oif);
if (!m && (strict & RT6_LOOKUP_F_IFACE))
- return -1;
+ return RT6_NUD_FAIL_HARD;
#ifdef CONFIG_IPV6_ROUTER_PREF
m |= IPV6_DECODE_PREF(IPV6_EXTRACT_PREF(rt->rt6i_flags)) << 2;
#endif
- if (!rt6_check_neigh(rt) && (strict & RT6_LOOKUP_F_REACHABLE))
- return -1;
+ if (strict & RT6_LOOKUP_F_REACHABLE) {
+ int n = rt6_check_neigh(rt);
+ if (n < 0)
+ return n;
+ }
return m;
}
static struct rt6_info *find_match(struct rt6_info *rt, int oif, int strict,
- int *mpri, struct rt6_info *match)
+ int *mpri, struct rt6_info *match,
+ bool *do_rr)
{
int m;
+ bool match_do_rr = false;
if (rt6_check_expired(rt))
goto out;
m = rt6_score_route(rt, oif, strict);
- if (m < 0)
+ if (m == RT6_NUD_FAIL_SOFT && !IS_ENABLED(CONFIG_IPV6_ROUTER_PREF)) {
+ match_do_rr = true;
+ m = 0; /* lowest valid score */
+ } else if (m < 0) {
goto out;
+ }
+
+ if (strict & RT6_LOOKUP_F_REACHABLE)
+ rt6_probe(rt);
if (m > *mpri) {
- if (strict & RT6_LOOKUP_F_REACHABLE)
- rt6_probe(match);
+ *do_rr = match_do_rr;
*mpri = m;
match = rt;
- } else if (strict & RT6_LOOKUP_F_REACHABLE) {
- rt6_probe(rt);
}
-
out:
return match;
}
static struct rt6_info *find_rr_leaf(struct fib6_node *fn,
struct rt6_info *rr_head,
- u32 metric, int oif, int strict)
+ u32 metric, int oif, int strict,
+ bool *do_rr)
{
struct rt6_info *rt, *match;
int mpri = -1;
@@ -606,10 +622,10 @@ static struct rt6_info *find_rr_leaf(str
match = NULL;
for (rt = rr_head; rt && rt->rt6i_metric == metric;
rt = rt->dst.rt6_next)
- match = find_match(rt, oif, strict, &mpri, match);
+ match = find_match(rt, oif, strict, &mpri, match, do_rr);
for (rt = fn->leaf; rt && rt != rr_head && rt->rt6i_metric == metric;
rt = rt->dst.rt6_next)
- match = find_match(rt, oif, strict, &mpri, match);
+ match = find_match(rt, oif, strict, &mpri, match, do_rr);
return match;
}
@@ -618,15 +634,16 @@ static struct rt6_info *rt6_select(struc
{
struct rt6_info *match, *rt0;
struct net *net;
+ bool do_rr = false;
rt0 = fn->rr_ptr;
if (!rt0)
fn->rr_ptr = rt0 = fn->leaf;
- match = find_rr_leaf(fn, rt0, rt0->rt6i_metric, oif, strict);
+ match = find_rr_leaf(fn, rt0, rt0->rt6i_metric, oif, strict,
+ &do_rr);
- if (!match &&
- (strict & RT6_LOOKUP_F_REACHABLE)) {
+ if (do_rr) {
struct rt6_info *next = rt0->dst.rt6_next;
/* no entries matched; do round-robin */
--
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