Messages in this thread | | | Subject | Re: [PATCH v2 bpf] bpf, test_run: fix &xdp_frame misplacement for LIVE_FRAMES | From | Daniel Borkmann <> | Date | Tue, 14 Feb 2023 16:24:10 +0100 |
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On 2/13/23 3:27 PM, Alexander Lobakin wrote: > &xdp_buff and &xdp_frame are bound in a way that > > xdp_buff->data_hard_start == xdp_frame > > It's always the case and e.g. xdp_convert_buff_to_frame() relies on > this. > IOW, the following: > > for (u32 i = 0; i < 0xdead; i++) { > xdpf = xdp_convert_buff_to_frame(&xdp); > xdp_convert_frame_to_buff(xdpf, &xdp); > } > > shouldn't ever modify @xdpf's contents or the pointer itself. > However, "live packet" code wrongly treats &xdp_frame as part of its > context placed *before* the data_hard_start. With such flow, > data_hard_start is sizeof(*xdpf) off to the right and no longer points > to the XDP frame. > > Instead of replacing `sizeof(ctx)` with `offsetof(ctx, xdpf)` in several > places and praying that there are no more miscalcs left somewhere in the > code, unionize ::frm with ::data in a flex array, so that both starts > pointing to the actual data_hard_start and the XDP frame actually starts > being a part of it, i.e. a part of the headroom, not the context. > A nice side effect is that the maximum frame size for this mode gets > increased by 40 bytes, as xdp_buff::frame_sz includes everything from > data_hard_start (-> includes xdpf already) to the end of XDP/skb shared > info. > > Minor: align `&head->data` with how `head->frm` is assigned for > consistency. > Minor #2: rename 'frm' to 'frame' in &xdp_page_head while at it for > clarity. > > (was found while testing XDP traffic generator on ice, which calls > xdp_convert_frame_to_buff() for each XDP frame) > > Fixes: b530e9e1063e ("bpf: Add "live packet" mode for XDP in BPF_PROG_RUN") > Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Could you double check BPF CI? Looks like a number of XDP related tests are failing on your patch which I'm not seeing on other patches where runs are green, for example test_progs on several archs report the below:
https://github.com/kernel-patches/bpf/actions/runs/4164593416/jobs/7207290499
[...] test_xdp_do_redirect:PASS:prog_run 0 nsec test_xdp_do_redirect:PASS:pkt_count_xdp 0 nsec test_xdp_do_redirect:PASS:pkt_count_zero 0 nsec test_xdp_do_redirect:PASS:pkt_count_tc 0 nsec test_max_pkt_size:PASS:prog_run_max_size 0 nsec test_max_pkt_size:FAIL:prog_run_too_big unexpected prog_run_too_big: actual -28 != expected -22 close_netns:PASS:setns 0 nsec #275 xdp_do_redirect:FAIL Summary: 273/1581 PASSED, 21 SKIPPED, 2 FAILED
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