From 73f51d151e6c760d74d7d4bde75337ebe5693b3e Mon Sep 17 00:00:00 2001 From: Stefano Brivio Date: Mon, 27 May 2019 19:42:23 +0200 Subject: [PATCH] selftests: pmtu: Fix encapsulating device in pmtu_vti6_link_change_mtu In the pmtu_vti6_link_change_mtu test, both local and remote addresses for the vti6 tunnel are assigned to the same address given to the dummy interface that we use as encapsulating device with a known MTU. This works as long as the dummy interface is actually selected, via rt6_lookup(), as encapsulating device. But if the remote address of the tunnel is a local address too, the loopback interface could also be selected, and there's nothing wrong with it. This is what some older -stable kernels do (3.18.z, at least), and nothing prevents us from subtly changing FIB implementation to revert back to that behaviour in the future. Define an IPv6 prefix instead, and use two separate addresses as local and remote for vti6, so that the encapsulating device can't be a loopback interface. Reported-by: Xiumei Mu Fixes: 1fad59ea1c34 ("selftests: pmtu: Add pmtu_vti6_link_change_mtu test") Signed-off-by: Stefano Brivio Signed-off-by: David S. Miller --- tools/testing/selftests/net/pmtu.sh | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/tools/testing/selftests/net/pmtu.sh b/tools/testing/selftests/net/pmtu.sh index b9171a7b3aaa..317dafcd605d 100755 --- a/tools/testing/selftests/net/pmtu.sh +++ b/tools/testing/selftests/net/pmtu.sh @@ -208,8 +208,8 @@ tunnel6_a_addr="fd00:2::a" tunnel6_b_addr="fd00:2::b" tunnel6_mask="64" -dummy6_0_addr="fc00:1000::0" -dummy6_1_addr="fc00:1001::0" +dummy6_0_prefix="fc00:1000::" +dummy6_1_prefix="fc00:1001::" dummy6_mask="64" cleanup_done=1 @@ -1005,13 +1005,13 @@ test_pmtu_vti6_link_change_mtu() { run_cmd ${ns_a} ip link set dummy0 up run_cmd ${ns_a} ip link set dummy1 up - run_cmd ${ns_a} ip addr add ${dummy6_0_addr}/${dummy6_mask} dev dummy0 - run_cmd ${ns_a} ip addr add ${dummy6_1_addr}/${dummy6_mask} dev dummy1 + run_cmd ${ns_a} ip addr add ${dummy6_0_prefix}1/${dummy6_mask} dev dummy0 + run_cmd ${ns_a} ip addr add ${dummy6_1_prefix}1/${dummy6_mask} dev dummy1 fail=0 # Create vti6 interface bound to device, passing MTU, check it - run_cmd ${ns_a} ip link add vti6_a mtu 1300 type vti6 remote ${dummy6_0_addr} local ${dummy6_0_addr} + run_cmd ${ns_a} ip link add vti6_a mtu 1300 type vti6 remote ${dummy6_0_prefix}2 local ${dummy6_0_prefix}1 mtu="$(link_get_mtu "${ns_a}" vti6_a)" if [ ${mtu} -ne 1300 ]; then err " vti6 MTU ${mtu} doesn't match configured value 1300" @@ -1020,7 +1020,7 @@ test_pmtu_vti6_link_change_mtu() { # Move to another device with different MTU, without passing MTU, check # MTU is adjusted - run_cmd ${ns_a} ip link set vti6_a type vti6 remote ${dummy6_1_addr} local ${dummy6_1_addr} + run_cmd ${ns_a} ip link set vti6_a type vti6 remote ${dummy6_1_prefix}2 local ${dummy6_1_prefix}1 mtu="$(link_get_mtu "${ns_a}" vti6_a)" if [ ${mtu} -ne $((3000 - 40)) ]; then err " vti MTU ${mtu} is not dummy MTU 3000 minus IPv6 header length" @@ -1028,7 +1028,7 @@ test_pmtu_vti6_link_change_mtu() { fi # Move it back, passing MTU, check MTU is not overridden - run_cmd ${ns_a} ip link set vti6_a mtu 1280 type vti6 remote ${dummy6_0_addr} local ${dummy6_0_addr} + run_cmd ${ns_a} ip link set vti6_a mtu 1280 type vti6 remote ${dummy6_0_prefix}2 local ${dummy6_0_prefix}1 mtu="$(link_get_mtu "${ns_a}" vti6_a)" if [ ${mtu} -ne 1280 ]; then err " vti6 MTU ${mtu} doesn't match configured value 1280" -- GitLab