linux-kernel - Re: [PATCH v5 bpf 0/4] lwt: fix return values of BPF ops

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Date:   Wed, 16 Aug 2023 16:27:14 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Yan Zhai <yan@...udflare.com>, bpf@...r.kernel.org
Cc:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        David Ahern <dsahern@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        Song Liu <song@...nel.org>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Stanislav Fomichev <sdf@...gle.com>,
        Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
        Mykola Lysenko <mykolal@...com>, Shuah Khan <shuah@...nel.org>,
        Thomas Graf <tgraf@...g.ch>,
        Jordan Griege <jgriege@...udflare.com>,
        Dan Carpenter <dan.carpenter@...aro.org>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        linux-kselftest@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v5 bpf 0/4] lwt: fix return values of BPF ops

Hi Yan,

On 8/16/23 4:54 AM, Yan Zhai wrote:
> lwt xmit hook does not expect positive return values in function
> ip_finish_output2 and ip6_finish_output. However, BPF programs can
> directly return positive statuses such like NET_XMIT_DROP, NET_RX_DROP,
> and etc to the caller. Such return values would make the kernel continue
> processing already freed skbs and eventually panic.
> 
> This set fixes the return values from BPF ops to unexpected continue
> processing, and checks strictly on the correct continue condition for
> future proof. In addition, add missing selftests for BPF_REDIRECT
> and BPF_REROUTE cases for BPF-CI.
> 
> v4: https://lore.kernel.org/bpf/ZMD1sFTW8SFiex+x@debian.debian/T/
> v3: https://lore.kernel.org/bpf/cover.1690255889.git.yan@cloudflare.com/
> v2: https://lore.kernel.org/netdev/ZLdY6JkWRccunvu0@debian.debian/
> v1: https://lore.kernel.org/bpf/ZLbYdpWC8zt9EJtq@debian.debian/
> 
> changes since v4:
>   * fixed same error on BPF_REROUTE path
>   * re-implemented selftests under BPF-CI requirement

BPF CI failed: https://github.com/kernel-patches/bpf/actions/runs/5874202507/job/15929012788

Looks like due to dummy device issue. Either you might need to add this to
the tools/testing/selftests/bpf/config* or perhaps just use veth instead for
link_err dev.

Error from the above link:

Notice: Success: 370/3177, Skipped: 21, Failed: 2
Error: #131 lwt_redirect
   Error: #131 lwt_redirect
   test_lwt_redirect:PASS:pthread_create 0 nsec
Error: #131/1 lwt_redirect/lwt_redirect_normal
   Error: #131/1 lwt_redirect/lwt_redirect_normal
   test_lwt_redirect_run:PASS:netns_create 0 nsec
   open_netns:PASS:malloc token 0 nsec
   open_netns:PASS:open /proc/self/ns/net 0 nsec
   open_netns:PASS:open netns fd 0 nsec
   open_netns:PASS:setns 0 nsec
   test_lwt_redirect_run:PASS:setns 0 nsec
   open_tuntap:PASS:open(/dev/net/tun) 0 nsec
   open_tuntap:PASS:ioctl(TUNSETIFF) 0 nsec
   open_tuntap:PASS:fcntl(O_NONBLOCK) 0 nsec
   setup_redirect_target:PASS:open_tuntap 0 nsec
   setup_redirect_target:PASS:if_nametoindex 0 nsec
   setup_redirect_target:FAIL:ip link add link_err type dummy unexpected error: 512 (errno 0)
   test_lwt_redirect_normal:FAIL:setup_redirect_target unexpected setup_redirect_target: actual -1 < expected 0
   close_netns:PASS:setns 0 nsec
Error: #131/2 lwt_redirect/lwt_redirect_normal_nomac
   Error: #131/2 lwt_redirect/lwt_redirect_normal_nomac
   test_lwt_redirect_run:PASS:netns_create 0 nsec
   open_netns:PASS:malloc token 0 nsec
   open_netns:PASS:open /proc/self/ns/net 0 nsec
   open_netns:PASS:open netns fd 0 nsec
   open_netns:PASS:setns 0 nsec
   test_lwt_redirect_run:PASS:setns 0 nsec
   open_tuntap:PASS:open(/dev/net/tun) 0 nsec
   open_tuntap:PASS:ioctl(TUNSETIFF) 0 nsec
   open_tuntap:PASS:fcntl(O_NONBLOCK) 0 nsec
   setup_redirect_target:PASS:open_tuntap 0 nsec
   setup_redirect_target:PASS:if_nametoindex 0 nsec
   setup_redirect_target:FAIL:ip link add link_err type dummy unexpected error: 512 (errno 0)
   test_lwt_redirect_normal_nomac:FAIL:setup_redirect_target unexpected setup_redirect_target: actual -1 < expected 0
   close_netns:PASS:setns 0 nsec
Error: #131/3 lwt_redirect/lwt_redirect_dev_down
   Error: #131/3 lwt_redirect/lwt_redirect_dev_down
   test_lwt_redirect_run:PASS:netns_create 0 nsec
   open_netns:PASS:malloc token 0 nsec
   open_netns:PASS:open /proc/self/ns/net 0 nsec
   open_netns:PASS:open netns fd 0 nsec
   open_netns:PASS:setns 0 nsec
   test_lwt_redirect_run:PASS:setns 0 nsec
   open_tuntap:PASS:open(/dev/net/tun) 0 nsec
   open_tuntap:PASS:ioctl(TUNSETIFF) 0 nsec
   open_tuntap:PASS:fcntl(O_NONBLOCK) 0 nsec
   setup_redirect_target:PASS:open_tuntap 0 nsec
   setup_redirect_target:PASS:if_nametoindex 0 nsec
   setup_redirect_target:FAIL:ip link add link_err type dummy unexpected error: 512 (errno 0)
   __test_lwt_redirect_dev_down:FAIL:setup_redirect_target unexpected setup_redirect_target: actual -1 < expected 0
   close_netns:PASS:setns 0 nsec
Error: #131/4 lwt_redirect/lwt_redirect_dev_down_nomac
   Error: #131/4 lwt_redirect/lwt_redirect_dev_down_nomac
   test_lwt_redirect_run:PASS:netns_create 0 nsec
   open_netns:PASS:malloc token 0 nsec
   open_netns:PASS:open /proc/self/ns/net 0 nsec
   open_netns:PASS:open netns fd 0 nsec
   open_netns:PASS:setns 0 nsec
   test_lwt_redirect_run:PASS:setns 0 nsec
   open_tuntap:PASS:open(/dev/net/tun) 0 nsec
   open_tuntap:PASS:ioctl(TUNSETIFF) 0 nsec
   open_tuntap:PASS:fcntl(O_NONBLOCK) 0 nsec
   setup_redirect_target:PASS:open_tuntap 0 nsec
   setup_redirect_target:PASS:if_nametoindex 0 nsec
   setup_redirect_target:FAIL:ip link add link_err type dummy unexpected error: 512 (errno 0)
   __test_lwt_redirect_dev_down:FAIL:setup_redirect_target unexpected setup_redirect_target: actual -1 < expected 0
   close_netns:PASS:setns 0 nsec
Error: #131/5 lwt_redirect/lwt_redirect_dev_carrier_down
   Error: #131/5 lwt_redirect/lwt_redirect_dev_carrier_down
   test_lwt_redirect_run:PASS:netns_create 0 nsec
   open_netns:PASS:malloc token 0 nsec
   open_netns:PASS:open /proc/self/ns/net 0 nsec
   open_netns:PASS:open netns fd 0 nsec
   open_netns:PASS:setns 0 nsec
   test_lwt_redirect_run:PASS:setns 0 nsec
   open_tuntap:PASS:open(/dev/net/tun) 0 nsec
   open_tuntap:PASS:ioctl(TUNSETIFF) 0 nsec
   open_tuntap:PASS:fcntl(O_NONBLOCK) 0 nsec
   setup_redirect_target:PASS:open_tuntap 0 nsec
   setup_redirect_target:PASS:if_nametoindex 0 nsec
   setup_redirect_target:FAIL:ip link add link_err type dummy unexpected error: 512 (errno 0)
   test_lwt_redirect_dev_carrier_down:FAIL:setup_redirect_target unexpected setup_redirect_target: actual -1 < expected 0
   close_netns:PASS:setns 0 nsec
   test_lwt_redirect:PASS:pthread_join 0 nsec
Error: #132 lwt_reroute
   Error: #132 lwt_reroute
   test_lwt_reroute:PASS:pthread_create 0 nsec
Error: #132/1 lwt_reroute/lwt_reroute_normal_xmit
   Error: #132/1 lwt_reroute/lwt_reroute_normal_xmit
   test_lwt_reroute_run:PASS:netns_create 0 nsec
   open_netns:PASS:malloc token 0 nsec
   open_netns:PASS:open /proc/self/ns/net 0 nsec
   open_netns:PASS:open netns fd 0 nsec
   open_netns:PASS:setns 0 nsec
   test_lwt_reroute_run:PASS:setns 0 nsec
   open_tuntap:PASS:open(/dev/net/tun) 0 nsec
   open_tuntap:PASS:ioctl(TUNSETIFF) 0 nsec
   open_tuntap:PASS:fcntl(O_NONBLOCK) 0 nsec
   setup:PASS:open_tun 0 nsec
   setup:PASS:if_nametoindex 0 nsec
   setup:FAIL:ip link add link_err type dummy unexpected error: 512 (errno 0)
   test_lwt_reroute_normal_xmit:FAIL:setup_reroute unexpected setup_reroute: actual -1 < expected 0
   close_netns:PASS:setns 0 nsec
Error: #132/2 lwt_reroute/lwt_reroute_qdisc_dropped
   Error: #132/2 lwt_reroute/lwt_reroute_qdisc_dropped
   test_lwt_reroute_run:PASS:netns_create 0 nsec
   open_netns:PASS:malloc token 0 nsec
   open_netns:PASS:open /proc/self/ns/net 0 nsec
   open_netns:PASS:open netns fd 0 nsec
   open_netns:PASS:setns 0 nsec
   test_lwt_reroute_run:PASS:setns 0 nsec
   open_tuntap:PASS:open(/dev/net/tun) 0 nsec
   open_tuntap:PASS:ioctl(TUNSETIFF) 0 nsec
   open_tuntap:PASS:fcntl(O_NONBLOCK) 0 nsec
   setup:PASS:open_tun 0 nsec
   setup:PASS:if_nametoindex 0 nsec
   setup:FAIL:ip link add link_err type dummy unexpected error: 512 (errno 0)
   test_lwt_reroute_qdisc_dropped:FAIL:setup_reroute unexpected setup_reroute: actual -1 < expected 0
   close_netns:PASS:setns 0 nsec
   test_lwt_reroute:PASS:pthread_join 0 nsec
Test Results:
              bpftool: PASS
           test_progs: FAIL (returned 1)
             shutdown: CLEAN
Error: Process completed with exit code 1.

Thanks,
Daniel