pwru: Add --output-skb-metadata and --output-xdp-metadata#509
Merged
brb merged 2 commits intocilium:mainfrom Apr 11, 2025
Merged
pwru: Add --output-skb-metadata and --output-xdp-metadata#509brb merged 2 commits intocilium:mainfrom
brb merged 2 commits intocilium:mainfrom
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Yep, this feature makes sense 👍 Mind updating the PR? |
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I will update the PR later. |
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Because the `filter_pcap_*` subprogs use its own stack memory, it is unnecessary to reserved 80B stack memory. Therefore, `filter_pcap_*` subprogs can use the whole stack memory. Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
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It's really useful to output specified metadatas of skb instead of outputing the whole skb btf data. However, it's not easy to `--output-skb-metadata 'skb->mark'` because the metadata is provided by users. Here're the steps to achieve it: 1. Parse the text to C AST. 2. Convert the C AST to bpf insns with `skb` btf type info. 3. Inject the `set_skb_metadata` stub with the generated insns. 4. Output the metadata with the provided field's btf type info. e.g. ```bash $ sudo ./pwru --filter-func 'icmp_rcv' --output-skb-metadata 'skb->hash' --output-skb-metadata 'skb->sw_hash' --output-skb-metadata 'skb->l4_hash' --filter-trace-xdp --output-xdp-metadata 'xdp->rxq->queue_index' host 1.1.1.1 2025/04/07 15:55:11 Attaching xdp progs... 2025/04/07 15:55:11 Attaching kprobes (via kprobe-multi)... 1 / 1 [----------------------------------------------------------------------------------------------------------------------------------------] 100.00% ? p/s 2025/04/07 15:55:11 Attached (ignored 0) 2025/04/07 15:55:11 Listening for events.. 2025/04/07 15:55:11 Failed to retrieve all ifaces from all network namespaces: open /proc/559446/ns/net: no such file or directory. Some iface names might be not shown. SKB CPU PROCESS NETNS MARK/x IFACE PROTO MTU LEN TUPLE FUNC 0xffffa64a81e67a38 6 ~wru/pwru:746016 4026531840 0 ens33:2 0x0000 1500 98 1.1.1.1:0->192.168.241.133:0(icmp) bpf_prog_3b185187f1855c4c_dummy[bpf](xdp) queue_index=0 0xffff991e4b8d5d00 6 ~wru/pwru:746016 4026531840 0 ens33:2 0x0800 65536 64 1.1.1.1:0->192.168.241.133:0(icmp) icmp_rcv hash=0 sw_hash=0 l4_hash=0 ^C2025/04/07 15:55:46 Received signal, exiting program.. 2025/04/07 15:55:46 Detaching kprobes... 1 / 1 [----------------------------------------------------------------------------------------------------------------------------------------] 100.00% ? p/s ``` Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
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jschwinger233
approved these changes
Apr 11, 2025
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Fixes #502
I'm porting such feature from bpfsnoop's
--output-arg 'skb->hash'.It's really useful to output specified metadatas of skb instead of outputing the whole skb btf data.
However, it's not easy to
--output-skb-metadata 'skb->mark'because the metadata is provided by users.Here're the steps to achieve it:
skbbtf type info.set_skb_metadatastub with the generated insns.e.g.