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52 lines
1.2 KiB
52 lines
1.2 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Minimal BPF assembler |
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* |
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* Instead of libpcap high-level filter expressions, it can be quite |
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* useful to define filters in low-level BPF assembler (that is kept |
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* close to Steven McCanne and Van Jacobson's original BPF paper). |
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* In particular for BPF JIT implementors, JIT security auditors, or |
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* just for defining BPF expressions that contain extensions which are |
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* not supported by compilers. |
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* |
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* How to get into it: |
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* |
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* 1) read Documentation/networking/filter.rst |
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* 2) Run `bpf_asm [-c] <filter-prog file>` to translate into binary |
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* blob that is loadable with xt_bpf, cls_bpf et al. Note: -c will |
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* pretty print a C-like construct. |
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* |
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* Copyright 2013 Daniel Borkmann <[email protected]> |
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*/ |
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#include <stdbool.h> |
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#include <stdio.h> |
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#include <string.h> |
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extern void bpf_asm_compile(FILE *fp, bool cstyle); |
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int main(int argc, char **argv) |
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{ |
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FILE *fp = stdin; |
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bool cstyle = false; |
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int i; |
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for (i = 1; i < argc; i++) { |
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if (!strncmp("-c", argv[i], 2)) { |
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cstyle = true; |
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continue; |
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} |
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fp = fopen(argv[i], "r"); |
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if (!fp) { |
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fp = stdin; |
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continue; |
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} |
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break; |
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} |
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bpf_asm_compile(fp, cstyle); |
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return 0; |
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}
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