[v9,bpf-next,0/5] Add skb + xdp dynptrs

Message

Joanne Koong Jan. 27, 2023, 7:16 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, there is no noticeable difference. Patch 5 contains more
details as well as examples of how to use skb and xdp dynptrs.

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

--
Changelog:

v8 = https://lore.kernel.org/bpf/[e-mail]/
v8 -> v9:
    * Fix dynptr_get_type() to check non-stack dynptrs 

v7 = https://lore.kernel.org/bpf/[e-mail]/
v7 -> v8:
    * Change helpers to kfuncs
    * Add 2 new patches (1/5 and 2/5)

v6 = https://lore.kernel.org/bpf/[e-mail]/
v6 -> v7
    * Change bpf_dynptr_data() to return read-only data slices if the skb prog
      is read-only (Martin)
    * Add test "skb_invalid_write" to test that writes to rd-only data slices
      are rejected

v5 = https://lore.kernel.org/bpf/[e-mail]/
v5 -> v6
    * Address kernel test robot errors by static inlining

v4 = https://lore.kernel.org/bpf/[e-mail]/
v4 -> v5
    * Address kernel test robot errors for configs w/out CONFIG_NET set
    * For data slices, return PTR_TO_MEM instead of PTR_TO_PACKET (Kumar)
    * Split selftests into subtests (Andrii)
    * Remove insn patching. Use rdonly and rdwr protos for dynptr skb
      construction (Andrii)
    * bpf_dynptr_data() returns NULL for rd-only dynptrs. There will be a
      separate bpf_dynptr_data_rdonly() added later (Andrii and Kumar)

v3 = https://lore.kernel.org/bpf/[e-mail]/
v3 -> v4
    * Forgot to commit --amend the kernel test robot error fixups

v2 = https://lore.kernel.org/bpf/[e-mail]/
v2 -> v3
    * Fix kernel test robot build test errors

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 (5):
  bpf: Allow "sk_buff" and "xdp_buff" as valid kfunc arg types
  bpf: Allow initializing dynptrs in kfuncs
  bpf: Add skb dynptrs
  bpf: Add xdp dynptrs
  selftests/bpf: tests for using dynptrs to parse skb and xdp buffers

 include/linux/bpf.h                           |  88 +-
 include/linux/bpf_verifier.h                  |   3 -
 include/linux/filter.h                        |  38 +
 include/uapi/linux/bpf.h                      |  41 +-
 kernel/bpf/btf.c                              |  22 +
 kernel/bpf/helpers.c                          | 107 +-
 kernel/bpf/verifier.c                         | 325 +++---
 net/core/filter.c                             | 104 +-
 tools/include/uapi/linux/bpf.h                |  41 +-
 .../selftests/bpf/prog_tests/cls_redirect.c   |  25 +
 .../testing/selftests/bpf/prog_tests/dynptr.c |  63 +-
 .../selftests/bpf/prog_tests/l4lb_all.c       |   2 +
 .../bpf/prog_tests/parse_tcp_hdr_opt.c        |  93 ++
 .../selftests/bpf/prog_tests/xdp_attach.c     |  11 +-
 .../testing/selftests/bpf/progs/dynptr_fail.c | 124 +++
 .../selftests/bpf/progs/dynptr_success.c      |  28 +
 .../bpf/progs/test_cls_redirect_dynptr.c      | 973 ++++++++++++++++++
 .../bpf/progs/test_l4lb_noinline_dynptr.c     | 474 +++++++++
 .../bpf/progs/test_parse_tcp_hdr_opt.c        | 119 +++
 .../bpf/progs/test_parse_tcp_hdr_opt_dynptr.c | 112 ++
 .../selftests/bpf/progs/test_xdp_dynptr.c     | 237 +++++
 .../selftests/bpf/test_tcp_hdr_options.h      |   1 +
 22 files changed, 2827 insertions(+), 204 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