Re: [PATCH v2] ipv6: do not free rt if FIB_LOOKUP_NOREF is set on suppress rule

[David Ahern]

On 9/24/19 8:01 AM, Jason A. Donenfeld wrote:
> Commit 7d9e5f422150 removed references from certain dsts, but accounting
> for this never translated down into the fib6 suppression code. This bug
> was triggered by WireGuard users who use wg-quick(8), which uses the
> "suppress-prefix" directive to ip-rule(8) for routing all of their
> internet traffic without routing loops. The test case added here
> causes the reference underflow by causing packets to evaluate a suppress
> rule.
> 
> Cc: sta...@vger.kernel.org
> Fixes: 7d9e5f422150 ("ipv6: convert major tx path to use 
> RT6_LOOKUP_F_DST_NOREF")
> Signed-off-by: Jason A. Donenfeld 
> ---
>  net/ipv6/fib6_rules.c|  3 ++-
>  tools/testing/selftests/net/fib_tests.sh | 17 -
>  2 files changed, 18 insertions(+), 2 deletions(-)

Thanks for adding the test case.

Reviewed-by: David Ahern 

Re: [PATCH v2] ipv6: do not free rt if FIB_LOOKUP_NOREF is set on suppress rule

[David Miller]

From: "Jason A. Donenfeld" 
Date: Tue, 24 Sep 2019 16:01:28 +0200

> Commit 7d9e5f422150 removed references from certain dsts, but accounting
> for this never translated down into the fib6 suppression code. This bug
> was triggered by WireGuard users who use wg-quick(8), which uses the
> "suppress-prefix" directive to ip-rule(8) for routing all of their
> internet traffic without routing loops. The test case added here
> causes the reference underflow by causing packets to evaluate a suppress
> rule.
> 
> Cc: sta...@vger.kernel.org

Please don't CC: stable for networking fixes, I handle these manually as per
the netdev FAQ.

> Fixes: 7d9e5f422150 ("ipv6: convert major tx path to use 
> RT6_LOOKUP_F_DST_NOREF")
> Signed-off-by: Jason A. Donenfeld 

Applied and queued up for -stable, thanks.

Re: [PATCH v2] ipv6: do not free rt if FIB_LOOKUP_NOREF is set on suppress rule

[Wei Wang]

On Tue, Sep 24, 2019 at 7:01 AM Jason A. Donenfeld  wrote:
>
> Commit 7d9e5f422150 removed references from certain dsts, but accounting
> for this never translated down into the fib6 suppression code. This bug
> was triggered by WireGuard users who use wg-quick(8), which uses the
> "suppress-prefix" directive to ip-rule(8) for routing all of their
> internet traffic without routing loops. The test case added here
> causes the reference underflow by causing packets to evaluate a suppress
> rule.
>
> Cc: sta...@vger.kernel.org
> Fixes: 7d9e5f422150 ("ipv6: convert major tx path to use 
> RT6_LOOKUP_F_DST_NOREF")
> Signed-off-by: Jason A. Donenfeld 
> ---
Acked-by: Wei Wang 

Good catch. Thanks for the fix.

>  net/ipv6/fib6_rules.c|  3 ++-
>  tools/testing/selftests/net/fib_tests.sh | 17 -
>  2 files changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/net/ipv6/fib6_rules.c b/net/ipv6/fib6_rules.c
> index d22b6c140f23..f9e8fe3ff0c5 100644
> --- a/net/ipv6/fib6_rules.c
> +++ b/net/ipv6/fib6_rules.c
> @@ -287,7 +287,8 @@ static bool fib6_rule_suppress(struct fib_rule *rule, 
> struct fib_lookup_arg *arg
> return false;
>
>  suppress_route:
> -   ip6_rt_put(rt);
> +   if (!(arg->flags & FIB_LOOKUP_NOREF))
> +   ip6_rt_put(rt);
> return true;
>  }
>
> diff --git a/tools/testing/selftests/net/fib_tests.sh 
> b/tools/testing/selftests/net/fib_tests.sh
> index 4465fc2dae14..c2c5f2bf0f95 100755
> --- a/tools/testing/selftests/net/fib_tests.sh
> +++ b/tools/testing/selftests/net/fib_tests.sh
> @@ -9,7 +9,7 @@ ret=0
>  ksft_skip=4
>
>  # all tests in this script. Can be overridden with -t option
> -TESTS="unregister down carrier nexthop ipv6_rt ipv4_rt ipv6_addr_metric 
> ipv4_addr_metric ipv6_route_metrics ipv4_route_metrics ipv4_route_v6_gw 
> rp_filter"
> +TESTS="unregister down carrier nexthop suppress ipv6_rt ipv4_rt 
> ipv6_addr_metric ipv4_addr_metric ipv6_route_metrics ipv4_route_metrics 
> ipv4_route_v6_gw rp_filter"
>
>  VERBOSE=0
>  PAUSE_ON_FAIL=no
> @@ -614,6 +614,20 @@ fib_nexthop_test()
> cleanup
>  }
>
> +fib_suppress_test()
> +{
> +   $IP link add dummy1 type dummy
> +   $IP link set dummy1 up
> +   $IP -6 route add default dev dummy1
> +   $IP -6 rule add table main suppress_prefixlength 0
> +   ping -f -c 1000 -W 1 1234::1 || true
> +   $IP -6 rule del table main suppress_prefixlength 0
> +   $IP link del dummy1
> +
> +   # If we got here without crashing, we're good.
> +   return 0
> +}
> +
>  
> 
>  # Tests on route add and replace
>
> @@ -1591,6 +1605,7 @@ do
> fib_carrier_test|carrier)   fib_carrier_test;;
> fib_rp_filter_test|rp_filter)   fib_rp_filter_test;;
> fib_nexthop_test|nexthop)   fib_nexthop_test;;
> +   fib_suppress_test|suppress) fib_suppress_test;;
> ipv6_route_test|ipv6_rt)ipv6_route_test;;
> ipv4_route_test|ipv4_rt)ipv4_route_test;;
> ipv6_addr_metric)   ipv6_addr_metric_test;;
> --
> 2.21.0
>

[PATCH v2] ipv6: do not free rt if FIB_LOOKUP_NOREF is set on suppress rule

[Jason A. Donenfeld]

Commit 7d9e5f422150 removed references from certain dsts, but accounting
for this never translated down into the fib6 suppression code. This bug
was triggered by WireGuard users who use wg-quick(8), which uses the
"suppress-prefix" directive to ip-rule(8) for routing all of their
internet traffic without routing loops. The test case added here
causes the reference underflow by causing packets to evaluate a suppress
rule.

Cc: sta...@vger.kernel.org
Fixes: 7d9e5f422150 ("ipv6: convert major tx path to use 
RT6_LOOKUP_F_DST_NOREF")
Signed-off-by: Jason A. Donenfeld 
---
 net/ipv6/fib6_rules.c|  3 ++-
 tools/testing/selftests/net/fib_tests.sh | 17 -
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/fib6_rules.c b/net/ipv6/fib6_rules.c
index d22b6c140f23..f9e8fe3ff0c5 100644
--- a/net/ipv6/fib6_rules.c
+++ b/net/ipv6/fib6_rules.c
@@ -287,7 +287,8 @@ static bool fib6_rule_suppress(struct fib_rule *rule, 
struct fib_lookup_arg *arg
return false;
 
 suppress_route:
-   ip6_rt_put(rt);
+   if (!(arg->flags & FIB_LOOKUP_NOREF))
+   ip6_rt_put(rt);
return true;
 }
 
diff --git a/tools/testing/selftests/net/fib_tests.sh 
b/tools/testing/selftests/net/fib_tests.sh
index 4465fc2dae14..c2c5f2bf0f95 100755
--- a/tools/testing/selftests/net/fib_tests.sh
+++ b/tools/testing/selftests/net/fib_tests.sh
@@ -9,7 +9,7 @@ ret=0
 ksft_skip=4
 
 # all tests in this script. Can be overridden with -t option
-TESTS="unregister down carrier nexthop ipv6_rt ipv4_rt ipv6_addr_metric 
ipv4_addr_metric ipv6_route_metrics ipv4_route_metrics ipv4_route_v6_gw 
rp_filter"
+TESTS="unregister down carrier nexthop suppress ipv6_rt ipv4_rt 
ipv6_addr_metric ipv4_addr_metric ipv6_route_metrics ipv4_route_metrics 
ipv4_route_v6_gw rp_filter"
 
 VERBOSE=0
 PAUSE_ON_FAIL=no
@@ -614,6 +614,20 @@ fib_nexthop_test()
cleanup
 }
 
+fib_suppress_test()
+{
+   $IP link add dummy1 type dummy
+   $IP link set dummy1 up
+   $IP -6 route add default dev dummy1
+   $IP -6 rule add table main suppress_prefixlength 0
+   ping -f -c 1000 -W 1 1234::1 || true
+   $IP -6 rule del table main suppress_prefixlength 0
+   $IP link del dummy1
+
+   # If we got here without crashing, we're good.
+   return 0
+}
+
 

 # Tests on route add and replace
 
@@ -1591,6 +1605,7 @@ do
fib_carrier_test|carrier)   fib_carrier_test;;
fib_rp_filter_test|rp_filter)   fib_rp_filter_test;;
fib_nexthop_test|nexthop)   fib_nexthop_test;;
+   fib_suppress_test|suppress) fib_suppress_test;;
ipv6_route_test|ipv6_rt)ipv6_route_test;;
ipv4_route_test|ipv4_rt)ipv4_route_test;;
ipv6_addr_metric)   ipv6_addr_metric_test;;
-- 
2.21.0