From 94c821c74bf5fe0c25e09df5334a16f98608db90 Mon Sep 17 00:00:00 2001 From: Seth David Schoen Date: Wed, 12 May 2021 21:37:49 -0700 Subject: [PATCH 1/2] ip: Treat IPv4 segment's lowest address as unicast Treat only the highest, not the lowest, IPv4 address within a local subnet as a broadcast address. Signed-off-by: Seth David Schoen Suggested-by: John Gilmore Acked-by: Dave Taht Reviewed-by: David Ahern Signed-off-by: David S. Miller --- net/ipv4/fib_frontend.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c index 84bb707bd88d..bfb345c88271 100644 --- a/net/ipv4/fib_frontend.c +++ b/net/ipv4/fib_frontend.c @@ -1122,10 +1122,8 @@ void fib_add_ifaddr(struct in_ifaddr *ifa) prefix, ifa->ifa_prefixlen, prim, ifa->ifa_rt_priority); - /* Add network specific broadcasts, when it takes a sense */ + /* Add the network broadcast address, when it makes sense */ if (ifa->ifa_prefixlen < 31) { - fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix, 32, - prim, 0); fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix | ~mask, 32, prim, 0); } From 6101ca0384e3778cf6ad4f938fbc094a0386ec01 Mon Sep 17 00:00:00 2001 From: Seth David Schoen Date: Wed, 12 May 2021 21:38:25 -0700 Subject: [PATCH 2/2] selftests: Lowest IPv4 address in a subnet is valid Expect the lowest IPv4 address in a subnet to be assignable and addressable as a unicast (non-broadcast) address on a local network segment. Signed-off-by: Seth David Schoen Suggested-by: John Gilmore Acked-by: Dave Taht Reviewed-by: David Ahern Signed-off-by: David S. Miller --- .../testing/selftests/net/unicast_extensions.sh | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/tools/testing/selftests/net/unicast_extensions.sh b/tools/testing/selftests/net/unicast_extensions.sh index dbf0421986df..66354cdd5ce4 100755 --- a/tools/testing/selftests/net/unicast_extensions.sh +++ b/tools/testing/selftests/net/unicast_extensions.sh @@ -189,6 +189,15 @@ segmenttest 255.255.255.1 255.255.255.254 24 "assign and ping inside 255.255.255 route_test 240.5.6.7 240.5.6.1 255.1.2.1 255.1.2.3 24 "route between 240.5.6/24 and 255.1.2/24 (is allowed)" route_test 0.200.6.7 0.200.38.1 245.99.101.1 245.99.200.111 16 "route between 0.200/16 and 245.99/16 (is allowed)" # +# Test support for lowest address ending in .0 +segmenttest 5.10.15.20 5.10.15.0 24 "assign and ping lowest address (/24)" +# +# Test support for lowest address not ending in .0 +segmenttest 192.168.101.192 192.168.101.193 26 "assign and ping lowest address (/26)" +# +# Routing using lowest address as a gateway/endpoint +route_test 192.168.42.1 192.168.42.0 9.8.7.6 9.8.7.0 24 "routing using lowest address" +# # ============================================== # ==== TESTS THAT CURRENTLY EXPECT FAILURE ===== # ============================================== @@ -202,14 +211,6 @@ segmenttest 255.255.255.1 255.255.255.255 16 "assigning 255.255.255.255 (is forb # Currently Linux does not allow this, so this should fail too segmenttest 127.99.4.5 127.99.4.6 16 "assign and ping inside 127/8 (is forbidden)" # -# Test support for lowest address -# Currently Linux does not allow this, so this should fail too -segmenttest 5.10.15.20 5.10.15.0 24 "assign and ping lowest address (is forbidden)" -# -# Routing using lowest address as a gateway/endpoint -# Currently Linux does not allow this, so this should fail too -route_test 192.168.42.1 192.168.42.0 9.8.7.6 9.8.7.0 24 "routing using lowest address (is forbidden)" -# # Test support for unicast use of class D # Currently Linux does not allow this, so this should fail too segmenttest 225.1.2.3 225.1.2.200 24 "assign and ping class D address (is forbidden)"