[PATCH 3.12 48/91] netfilter: ipt_rpfilter: remove the nh_scope test in rpfilter_lookup_reverse

From: Jiri Slaby
Date: Tue Jan 05 2016 - 12:55:10 EST


From: lucien <lucien.xin@xxxxxxxxx>

3.12-stable review patch. If anyone has any objections, please let me know.

===============

commit cc4998febd567d1c671684abce5595344bd4e8b2 upstream.

--accept-local option works for res.type == RTN_LOCAL, which should be
from the local table, but there, the fib_info's nh->nh_scope =
RT_SCOPE_NOWHERE ( > RT_SCOPE_HOST). in fib_create_info().

if (cfg->fc_scope == RT_SCOPE_HOST) {
struct fib_nh *nh = fi->fib_nh;

/* Local address is added. */
if (nhs != 1 || nh->nh_gw)
goto err_inval;
nh->nh_scope = RT_SCOPE_NOWHERE; <===
nh->nh_dev = dev_get_by_index(net, fi->fib_nh->nh_oif);
err = -ENODEV;
if (!nh->nh_dev)
goto failure;

but in our rpfilter_lookup_reverse():

if (dev_match || flags & XT_RPFILTER_LOOSE)
return FIB_RES_NH(res).nh_scope <= RT_SCOPE_HOST;

if nh->nh_scope > RT_SCOPE_HOST, it will fail. --accept-local option
will never be passed.

it seems the test is bogus and can be removed to fix this issue.

if (dev_match || flags & XT_RPFILTER_LOOSE)
return FIB_RES_NH(res).nh_scope <= RT_SCOPE_HOST;

ipv6 does not have this issue.

Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
Acked-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
net/ipv4/netfilter/ipt_rpfilter.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/net/ipv4/netfilter/ipt_rpfilter.c b/net/ipv4/netfilter/ipt_rpfilter.c
index c49dcd0284a0..56dd8ac6d28b 100644
--- a/net/ipv4/netfilter/ipt_rpfilter.c
+++ b/net/ipv4/netfilter/ipt_rpfilter.c
@@ -61,9 +61,7 @@ static bool rpfilter_lookup_reverse(struct flowi4 *fl4,
if (FIB_RES_DEV(res) == dev)
dev_match = true;
#endif
- if (dev_match || flags & XT_RPFILTER_LOOSE)
- return FIB_RES_NH(res).nh_scope <= RT_SCOPE_HOST;
- return dev_match;
+ return dev_match || flags & XT_RPFILTER_LOOSE;
}

static bool rpfilter_is_local(const struct sk_buff *skb)
--
2.6.4

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