1. 09 3月, 2018 6 次提交
  2. 30 12月, 2017 1 次提交
  3. 05 10月, 2017 2 次提交
  4. 16 11月, 2015 1 次提交
  5. 12 3月, 2014 1 次提交
  6. 12 12月, 2013 2 次提交
    • D
      filter: bpf_asm: add minimal bpf asm tool · 3f356385
      Daniel Borkmann 提交于
      There are a couple of valid use cases for a minimal low-level bpf asm
      like tool, for example, using/linking to libpcap is not an option, the
      required BPF filters use Linux extensions that are not supported by
      libpcap's compiler, a filter might be more complex and not cleanly
      implementable with libpcap's compiler, particular filter codes should
      be optimized differently than libpcap's internal BPF compiler does,
      or for security audits of emitted BPF JIT code for prepared set of BPF
      instructions resp. BPF JIT compiler development in general.
      
      Then, in such cases writing such a filter in low-level syntax can be
      an good alternative, for example, xt_bpf and cls_bpf users might have
      requirements that could result in more complex filter code, or one that
      cannot be expressed with libpcap (e.g. different return codes in
      cls_bpf for flowids on various BPF code paths).
      
      Moreover, BPF JIT implementors may wish to manually write test cases
      in order to verify the resulting JIT image, and thus need low-level
      access to BPF code generation as well. Therefore, complete the available
      toolchain for BPF with this small bpf_asm helper tool for the tools/net/
      directory. These 3 complementary minimal helper tools round up and
      facilitate BPF development.
      Signed-off-by: NDaniel Borkmann <dborkman@redhat.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      3f356385
    • D
      filter: bpf_dbg: add minimal bpf debugger · fd981e3c
      Daniel Borkmann 提交于
      This patch adds a minimal BPF debugger that "emulates" the kernel's
      BPF engine (w/o extensions) and allows for single stepping (forwards
      and backwards through BPF code) or running with >=1 breakpoints through
      selected or all packets from a pcap file with a provided user filter
      in order to facilitate verification of a BPF program. When a breakpoint
      is being hit, it dumps all register contents, decoded instructions and
      in case of branches both decoded branch targets as well as other useful
      information.
      
      Having this facility is in particular useful to verify BPF programs
      against given test traffic *before* attaching to a live system.
      
      With the general availability of cls_bpf, xt_bpf, socket filters,
      team driver and e.g. PTP code, all BPF users, quite often a single
      more complex BPF program is being used. Reasons for a more complex
      BPF program are primarily to optimize execution time for making a
      verdict when multiple simple BPF programs are combined into one in
      order to prevent parsing same headers multiple times. In particular,
      for cls_bpf that can have various return paths for encoding flowids,
      and xt_bpf to come to a fw verdict this can be the case.
      
      Therefore, as this can result in more complex and harder to debug
      code, it would be very useful to have this minimal tool for testing
      purposes. It can also be of help for BPF JIT developers as filters
      are "test attached" to the kernel on a temporary socket thus
      triggering a JIT image dump when enabled. The tool uses an interactive
      libreadline shell with auto-completion and history support.
      Signed-off-by: NDaniel Borkmann <dborkman@redhat.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      fd981e3c
  7. 21 3月, 2013 1 次提交
    • D
      filter: add minimal BPF JIT image disassembler · e306e2c1
      Daniel Borkmann 提交于
      This is a minimal stand-alone user space helper, that allows for debugging or
      verification of emitted BPF JIT images. This is in particular useful for
      emitted opcode debugging, since minor bugs in the JIT compiler can be fatal.
      The disassembler is architecture generic and uses libopcodes and libbfd.
      
      How to get to the disassembly, example:
      
        1) `echo 2 > /proc/sys/net/core/bpf_jit_enable`
        2) Load a BPF filter (e.g. `tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24`)
        3) Run e.g. `bpf_jit_disasm -o` to disassemble the most recent JIT code output
      
      `bpf_jit_disasm -o` will display the related opcodes to a particular instruction
      as well. Example for x86_64:
      
      $ ./bpf_jit_disasm
      94 bytes emitted from JIT compiler (pass:3, flen:9)
      ffffffffa0356000 + <x>:
         0:	push   %rbp
         1:	mov    %rsp,%rbp
         4:	sub    $0x60,%rsp
         8:	mov    %rbx,-0x8(%rbp)
         c:	mov    0x68(%rdi),%r9d
        10:	sub    0x6c(%rdi),%r9d
        14:	mov    0xe0(%rdi),%r8
        1b:	mov    $0xc,%esi
        20:	callq  0xffffffffe0d01b71
        25:	cmp    $0x86dd,%eax
        2a:	jne    0x000000000000003d
        2c:	mov    $0x14,%esi
        31:	callq  0xffffffffe0d01b8d
        36:	cmp    $0x6,%eax
      [...]
        5c:	leaveq
        5d:	retq
      
      $ ./bpf_jit_disasm -o
      94 bytes emitted from JIT compiler (pass:3, flen:9)
      ffffffffa0356000 + <x>:
         0:	push   %rbp
      	55
         1:	mov    %rsp,%rbp
      	48 89 e5
         4:	sub    $0x60,%rsp
      	48 83 ec 60
         8:	mov    %rbx,-0x8(%rbp)
      	48 89 5d f8
         c:	mov    0x68(%rdi),%r9d
      	44 8b 4f 68
        10:	sub    0x6c(%rdi),%r9d
      	44 2b 4f 6c
      [...]
        5c:	leaveq
      	c9
        5d:	retq
      	c3
      Signed-off-by: NDaniel Borkmann <dborkman@redhat.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      e306e2c1