[PATCH bpf-next v4 0/3] Add skb + xdp dynptrs

Joanne Koong
2022-08-22T23:57:25Z

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/20220523210712.3641569-1-joannelkoong@gmail.com/

--
Changelog:

v3 = https://lore.kernel.org/bpf/20220822193442.657638-1-joannelkoong@gmail.com/
v3 -> v4
* Forgot to commit --amend the kernel test robot error fixups

v2 = https://lore.kernel.org/bpf/20220811230501.2632393-1-joannelkoong@gmail.com/
v2 -> v3
* Fix kernel test robot build test errors

v1 = https://lore.kernel.org/bpf/20220726184706.954822-1-joannelkoong@gmail.com/
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 | 87 +-
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, 2693 insertions(+), 115 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

--
2.30.2