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linux: backport IPv6 SAS fixes for source-specific routes
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Signed-off-by: Steven Barth <steven@midlink.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@45699 3c298f89-4303-0410-b956-a3cf2f4a3e73
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cyrus committed May 19, 2015
1 parent 20cc83f commit 5168c9a
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98 changes: 98 additions & 0 deletions ...et/linux/generic/patches-3.18/667-ipv6-Fixed-source-specific-default-route-handling.patch
View file
@@ -0,0 +1,98 @@
From e16e888b525503be05b3aea64190e8b3bdef44d0 Mon Sep 17 00:00:00 2001
From: Markus Stenberg <markus.stenberg@iki.fi>
Date: Tue, 5 May 2015 13:36:59 +0300
Subject: [PATCH] ipv6: Fixed source specific default route handling.

If there are only IPv6 source specific default routes present, the
host gets -ENETUNREACH on e.g. connect() because ip6_dst_lookup_tail
calls ip6_route_output first, and given source address any, it fails,
and ip6_route_get_saddr is never called.

The change is to use the ip6_route_get_saddr, even if the initial
ip6_route_output fails, and then doing ip6_route_output _again_ after
we have appropriate source address available.

Note that this is '99% fix' to the problem; a correct fix would be to
do route lookups only within addrconf.c when picking a source address,
and never call ip6_route_output before source address has been
populated.

Signed-off-by: Markus Stenberg <markus.stenberg@iki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/ipv6/ip6_output.c | 39 +++++++++++++++++++++++++++++++--------
net/ipv6/route.c | 5 +++--
2 files changed, 34 insertions(+), 10 deletions(-)

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 7fde1f2..c217775 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -897,21 +897,45 @@ static int ip6_dst_lookup_tail(struct so
#endif
int err;

- if (*dst == NULL)
- *dst = ip6_route_output(net, sk, fl6);
-
- if ((err = (*dst)->error))
- goto out_err_release;
+ /* The correct way to handle this would be to do
+ * ip6_route_get_saddr, and then ip6_route_output; however,
+ * the route-specific preferred source forces the
+ * ip6_route_output call _before_ ip6_route_get_saddr.
+ *
+ * In source specific routing (no src=any default route),
+ * ip6_route_output will fail given src=any saddr, though, so
+ * that's why we try it again later.
+ */
+ if (ipv6_addr_any(&fl6->saddr) && (!*dst || !(*dst)->error)) {
+ struct rt6_info *rt;
+ bool had_dst = *dst != NULL;

- if (ipv6_addr_any(&fl6->saddr)) {
- struct rt6_info *rt = (struct rt6_info *) *dst;
+ if (!had_dst)
+ *dst = ip6_route_output(net, sk, fl6);
+ rt = (*dst)->error ? NULL : (struct rt6_info *)*dst;
err = ip6_route_get_saddr(net, rt, &fl6->daddr,
sk ? inet6_sk(sk)->srcprefs : 0,
&fl6->saddr);
if (err)
goto out_err_release;
+
+ /* If we had an erroneous initial result, pretend it
+ * never existed and let the SA-enabled version take
+ * over.
+ */
+ if (!had_dst && (*dst)->error) {
+ dst_release(*dst);
+ *dst = NULL;
+ }
}

+ if (!*dst)
+ *dst = ip6_route_output(net, sk, fl6);
+
+ err = (*dst)->error;
+ if (err)
+ goto out_err_release;
+
#ifdef CONFIG_IPV6_OPTIMISTIC_DAD
/*
* Here if the dst entry we've looked up
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2215,9 +2215,10 @@ int ip6_route_get_saddr(struct net *net,
unsigned int prefs,
struct in6_addr *saddr)
{
- struct inet6_dev *idev = ip6_dst_idev((struct dst_entry *)rt);
+ struct inet6_dev *idev =
+ rt ? ip6_dst_idev((struct dst_entry *)rt) : NULL;
int err = 0;
- if (rt->rt6i_prefsrc.plen)
+ if (rt && rt->rt6i_prefsrc.plen)
*saddr = rt->rt6i_prefsrc.addr;
else
err = ipv6_dev_get_saddr(net, idev ? idev->dev : NULL,
104 changes: 104 additions & 0 deletions target/linux/generic/patches-4.0/667-ipv6-Fixed-source-specific-default-route-handling.patch
View file
@@ -0,0 +1,104 @@
From e16e888b525503be05b3aea64190e8b3bdef44d0 Mon Sep 17 00:00:00 2001
From: Markus Stenberg <markus.stenberg@iki.fi>
Date: Tue, 5 May 2015 13:36:59 +0300
Subject: [PATCH] ipv6: Fixed source specific default route handling.

If there are only IPv6 source specific default routes present, the
host gets -ENETUNREACH on e.g. connect() because ip6_dst_lookup_tail
calls ip6_route_output first, and given source address any, it fails,
and ip6_route_get_saddr is never called.

The change is to use the ip6_route_get_saddr, even if the initial
ip6_route_output fails, and then doing ip6_route_output _again_ after
we have appropriate source address available.

Note that this is '99% fix' to the problem; a correct fix would be to
do route lookups only within addrconf.c when picking a source address,
and never call ip6_route_output before source address has been
populated.

Signed-off-by: Markus Stenberg <markus.stenberg@iki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/ipv6/ip6_output.c | 39 +++++++++++++++++++++++++++++++--------
net/ipv6/route.c | 5 +++--
2 files changed, 34 insertions(+), 10 deletions(-)

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 7fde1f2..c217775 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -886,22 +886,45 @@ static int ip6_dst_lookup_tail(struct sock *sk,
#endif
int err;

- if (!*dst)
- *dst = ip6_route_output(net, sk, fl6);
-
- err = (*dst)->error;
- if (err)
- goto out_err_release;
+ /* The correct way to handle this would be to do
+ * ip6_route_get_saddr, and then ip6_route_output; however,
+ * the route-specific preferred source forces the
+ * ip6_route_output call _before_ ip6_route_get_saddr.
+ *
+ * In source specific routing (no src=any default route),
+ * ip6_route_output will fail given src=any saddr, though, so
+ * that's why we try it again later.
+ */
+ if (ipv6_addr_any(&fl6->saddr) && (!*dst || !(*dst)->error)) {
+ struct rt6_info *rt;
+ bool had_dst = *dst != NULL;

- if (ipv6_addr_any(&fl6->saddr)) {
- struct rt6_info *rt = (struct rt6_info *) *dst;
+ if (!had_dst)
+ *dst = ip6_route_output(net, sk, fl6);
+ rt = (*dst)->error ? NULL : (struct rt6_info *)*dst;
err = ip6_route_get_saddr(net, rt, &fl6->daddr,
sk ? inet6_sk(sk)->srcprefs : 0,
&fl6->saddr);
if (err)
goto out_err_release;
+
+ /* If we had an erroneous initial result, pretend it
+ * never existed and let the SA-enabled version take
+ * over.
+ */
+ if (!had_dst && (*dst)->error) {
+ dst_release(*dst);
+ *dst = NULL;
+ }
}

+ if (!*dst)
+ *dst = ip6_route_output(net, sk, fl6);
+
+ err = (*dst)->error;
+ if (err)
+ goto out_err_release;
+
#ifdef CONFIG_IPV6_OPTIMISTIC_DAD
/*
* Here if the dst entry we've looked up
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 5c48293..d358888 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2245,9 +2245,10 @@ int ip6_route_get_saddr(struct net *net,
unsigned int prefs,
struct in6_addr *saddr)
{
- struct inet6_dev *idev = ip6_dst_idev((struct dst_entry *)rt);
+ struct inet6_dev *idev =
+ rt ? ip6_dst_idev((struct dst_entry *)rt) : NULL;
int err = 0;
- if (rt->rt6i_prefsrc.plen)
+ if (rt && rt->rt6i_prefsrc.plen)
*saddr = rt->rt6i_prefsrc.addr;
else
err = ipv6_dev_get_saddr(net, idev ? idev->dev : NULL,
--
2.1.4

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