----- On Sep 21, 2020, at 2:36 PM, David Ahern dsah...@gmail.com wrote: > On 9/18/20 12:17 PM, Mathieu Desnoyers wrote: >> Hi, >> >> Here is an updated series of fixes for ipv4 and ipv6 which which ensure >> the route lookup is performed on the right routing table in VRF >> configurations when sending TTL expired icmp errors (useful for >> traceroute). >> >> It includes tests for both ipv4 and ipv6. >> >> These fixes address specifically address the code paths involved in >> sending TTL expired icmp errors. As detailed in the individual commit >> messages, those fixes do not address similar issues related to network >> namespaces and unreachable / fragmentation needed messages, which appear >> to use different code paths. >> > > New selftests are failing: > TEST: Ping received ICMP frag needed [FAIL] > > Both IPv4 and IPv6 versions are failing.
Indeed, this situation is discussed in each patch commit message: ipv4: [ It has also been pointed out that a similar issue exists with unreachable / fragmentation needed messages, which can be triggered by changing the MTU of eth1 in r1 to 1400 and running: ip netns exec h1 ping -s 1450 -Mdo -c1 172.16.2.2 Some investigation points to raw_icmp_error() and raw_err() as being involved in this last scenario. The focus of this patch is TTL expired ICMP messages, which go through icmp_route_lookup. Investigation of failure modes related to raw_icmp_error() is beyond this investigation's scope. ] ipv6: [ Testing shows that similar issues exist with ipv6 unreachable / fragmentation needed messages. However, investigation of this additional failure mode is beyond this investigation's scope. ] I do not have the time to investigate further unfortunately, so I thought it best to post what I have. Note that network namespaces also probably have the same problem, but those are not covered by the test cases. Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
