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Commit d228b897 authored by Nicolas Dichtel's avatar Nicolas Dichtel Committed by Greg Kroah-Hartman
Browse files

ip: fix triggering of 'icmp redirect' 



commit eb55dc09b5dd040232d5de32812cc83001a23da6 upstream.

__mkroute_input() uses fib_validate_source() to trigger an icmp redirect.
My understanding is that fib_validate_source() is used to know if the src
address and the gateway address are on the same link. For that,
fib_validate_source() returns 1 (same link) or 0 (not the same network).
__mkroute_input() is the only user of these positive values, all other
callers only look if the returned value is negative.

Since the below patch, fib_validate_source() didn't return anymore 1 when
both addresses are on the same network, because the route lookup returns
RT_SCOPE_LINK instead of RT_SCOPE_HOST. But this is, in fact, right.
Let's adapat the test to return 1 again when both addresses are on the same
link.

CC: stable@vger.kernel.org
Fixes: 747c14307214 ("ip: fix dflt addr selection for connected nexthop")
Reported-by: default avatarkernel test robot <yujie.liu@intel.com>
Reported-by: default avatarHeng Qi <hengqi@linux.alibaba.com>
Signed-off-by: default avatarNicolas Dichtel <nicolas.dichtel@6wind.com>
Reviewed-by: default avatarDavid Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20220829100121.3821-1-nicolas.dichtel@6wind.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 66689c5c

net/ipv4/fib_frontend.c

+2 −2
Original line number Diff line number Diff line
@@ -399,7 +399,7 @@ static int __fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst, 
	dev_match = dev_match || (res.type == RTN_LOCAL &&

				  dev == net->loopback_dev);

	if (dev_match) {

		ret = FIB_RES_NHC(res)->nhc_scope >= RT_SCOPE_HOST;

		ret = FIB_RES_NHC(res)->nhc_scope >= RT_SCOPE_LINK;

		return ret;

	}

	if (no_addr)
@@ -411,7 +411,7 @@ static int __fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst, 
	ret = 0;

	if (fib_lookup(net, &fl4, &res, FIB_LOOKUP_IGNORE_LINKSTATE) == 0) {

		if (res.type == RTN_UNICAST)

			ret = FIB_RES_NHC(res)->nhc_scope >= RT_SCOPE_HOST;

			ret = FIB_RES_NHC(res)->nhc_scope >= RT_SCOPE_LINK;

	}

	return ret;