[bpf-next,v2,0/3] Add skb + xdp dynptrs

Message

Joanne Koong Aug. 11, 2022, 11:04 p.m. UTC

This patchset is the 2nd in the dynptr series. The 1st can be found here [0].

This patchset adds skb and xdp type dynptrs, which have two main benefits for
packet parsing:
    * allowing operations on sizes that are not statically known at
      compile-time (eg variable-sized accesses).
    * more ergonomic and less brittle iteration through data (eg does not need
      manual if checking for being within bounds of data_end)

When comparing the differences in runtime for packet parsing without dynptrs
vs. with dynptrs for the more simple cases, there is no noticeable difference.
For the more complex cases where lengths are non-statically known at compile
time, there can be a significant speed-up when using dynptrs (eg a 2x speed up
for cls redirection). Patch 3 contains more details as well as examples of how
to use skb and xdp dynptrs.

[0] https://lore.kernel.org/bpf/[e-mail]/

--
Changelog:

v1 = https://lore.kernel.org/bpf/[e-mail]/
v1 -> v2
  * Return data slices to rd-only skb dynptrs (Martin)
  * bpf_dynptr_write allows writes to frags for skb dynptrs, but always
    invalidates associated data slices (Martin)
  * Use switch casing instead of ifs (Andrii)
  * Use 0xFD for experimental kind number in the selftest (Zvi)
  * Put selftest conversions w/ dynptrs into new files (Alexei)
  * Add new selftest "test_cls_redirect_dynptr.c" 


Joanne Koong (3):
  bpf: Add skb dynptrs
  bpf: Add xdp dynptrs
  selftests/bpf: tests for using dynptrs to parse skb and xdp buffers

 include/linux/bpf.h                           |  14 +-
 include/linux/filter.h                        |   7 +
 include/uapi/linux/bpf.h                      |  59 +-
 kernel/bpf/helpers.c                          |  93 +-
 kernel/bpf/verifier.c                         | 105 +-
 net/core/filter.c                             |  99 +-
 tools/include/uapi/linux/bpf.h                |  59 +-
 .../selftests/bpf/prog_tests/cls_redirect.c   |  25 +
 .../testing/selftests/bpf/prog_tests/dynptr.c | 132 ++-
 .../selftests/bpf/prog_tests/l4lb_all.c       |   2 +
 .../bpf/prog_tests/parse_tcp_hdr_opt.c        |  85 ++
 .../selftests/bpf/prog_tests/xdp_attach.c     |   9 +-
 .../testing/selftests/bpf/progs/dynptr_fail.c | 111 ++
 .../selftests/bpf/progs/dynptr_success.c      |  29 +
 .../bpf/progs/test_cls_redirect_dynptr.c      | 968 ++++++++++++++++++
 .../bpf/progs/test_l4lb_noinline_dynptr.c     | 468 +++++++++
 .../bpf/progs/test_parse_tcp_hdr_opt.c        | 119 +++
 .../bpf/progs/test_parse_tcp_hdr_opt_dynptr.c | 110 ++
 .../selftests/bpf/progs/test_xdp_dynptr.c     | 240 +++++
 .../selftests/bpf/test_tcp_hdr_options.h      |   1 +
 20 files changed, 2649 insertions(+), 86 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/parse_tcp_hdr_opt.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_cls_redirect_dynptr.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_l4lb_noinline_dynptr.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_parse_tcp_hdr_opt.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_parse_tcp_hdr_opt_dynptr.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_dynptr.c