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/1592901278...

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