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From: YiFei Zhu <zhuyifei1999@gmail.com>
To: bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Stanislav Fomichev <sdf@google.com>,
	Mahesh Bandewar <maheshb@google.com>,
	YiFei Zhu <zhuyifei@google.com>
Subject: [PATCH bpf-next 0/5] Allow storage of flexible metadata information for eBPF programs
Date: Thu, 20 Aug 2020 04:42:06 -0500	[thread overview]
Message-ID: <cover.1597915265.git.zhuyifei@google.com> (raw)

From: YiFei Zhu <zhuyifei@google.com>

Currently, if a user wants to store arbitrary metadata for an eBPF
program, for example, the program build commit hash or version, they
could store it in a map, and conveniently libbpf uses .data section to
populate an internal map. However, if the program does not actually
reference the map, then the map would be de-refcounted and freed.

This patch set introduces a new syscall BPF_PROG_BIND_MAP to add a map
to a program's used_maps, even if the program instructions does not
reference the map. libbpf is extended to recognize the .metadata section
and load it as an internal map, and use the new syscall to ensure the
map is bound. bpftool is also extended to have a new flag to prog
subcommand, "--metadata" to dump the contents of the metadata section
without a separate map dump call.

An example use of this would be BPF C file declaring:

  char commit_hash[] SEC(".metadata") = "abcdef123456";

and bpftool would emit:

  $ bpftool prog --metadata
  [...]
  	metadata:
  		commit_hash = "abcdef123456"

Patch 1 protects the used_maps array and count with a mutex.

Patch 2 implements the new syscall.

Patch 3 extends libbpf to have a wrapper around the syscall, probe the
kernel for support of this new syscall, and use it on .metadata section
if supported and the section exists.

Patch 4 extends bpftool so that it is able to dump metadata from prog
show.

Patch 5 adds a test to check the metadata loading and dumping.

Changes since RFC:
* Fixed a few missing unlocks, and missing close while iterating map fds.
* Move mutex initialization to right after prog aux allocation, and mutex
  destroy to right after prog aux free.
* s/ADD_MAP/BIND_MAP/
* Use mutex only instead of RCU to protect the used_map array & count.

YiFei Zhu (5):
  bpf: Mutex protect used_maps array and count
  bpf: Add BPF_PROG_BIND_MAP syscall
  libbpf: Add BPF_PROG_BIND_MAP syscall and use it on .metadata section
  bpftool: support dumping metadata
  selftests/bpf: Test bpftool loading and dumping metadata

 .../net/ethernet/netronome/nfp/bpf/offload.c  |  18 ++-
 include/linux/bpf.h                           |   1 +
 include/uapi/linux/bpf.h                      |   7 +
 kernel/bpf/core.c                             |  15 +-
 kernel/bpf/syscall.c                          |  81 ++++++++++-
 net/core/dev.c                                |  11 +-
 tools/bpf/bpftool/json_writer.c               |   6 +
 tools/bpf/bpftool/json_writer.h               |   3 +
 tools/bpf/bpftool/main.c                      |  10 ++
 tools/bpf/bpftool/main.h                      |   1 +
 tools/bpf/bpftool/prog.c                      | 135 ++++++++++++++++++
 tools/include/uapi/linux/bpf.h                |   7 +
 tools/lib/bpf/bpf.c                           |  11 ++
 tools/lib/bpf/bpf.h                           |   1 +
 tools/lib/bpf/libbpf.c                        | 100 ++++++++++++-
 tools/lib/bpf/libbpf.map                      |   1 +
 tools/testing/selftests/bpf/Makefile          |   3 +-
 .../selftests/bpf/progs/metadata_unused.c     |  15 ++
 .../selftests/bpf/progs/metadata_used.c       |  15 ++
 .../selftests/bpf/test_bpftool_metadata.sh    |  82 +++++++++++
 20 files changed, 504 insertions(+), 19 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/progs/metadata_unused.c
 create mode 100644 tools/testing/selftests/bpf/progs/metadata_used.c
 create mode 100755 tools/testing/selftests/bpf/test_bpftool_metadata.sh

-- 
2.28.0


             reply	other threads:[~2020-08-20  9:43 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-20  9:42 YiFei Zhu [this message]
2020-08-20  9:42 ` [PATCH bpf-next 1/5] bpf: Mutex protect used_maps array and count YiFei Zhu
2020-08-20 21:18   ` Yonghong Song
2020-08-20  9:42 ` [PATCH bpf-next 2/5] bpf: Add BPF_PROG_BIND_MAP syscall YiFei Zhu
2020-08-20 21:23   ` Yonghong Song
2020-08-20  9:42 ` [PATCH bpf-next 3/5] libbpf: Add BPF_PROG_BIND_MAP syscall and use it on .metadata section YiFei Zhu
2020-08-20 20:38   ` Yonghong Song
2020-08-21  7:52     ` YiFei Zhu
2020-08-21 15:14       ` Yonghong Song
2020-08-25 20:45   ` Andrey Ignatov
2020-08-26  4:02   ` Andrii Nakryiko
2020-08-20  9:42 ` [PATCH bpf-next 4/5] bpftool: support dumping metadata YiFei Zhu
2020-08-20 21:11   ` Yonghong Song
2020-08-21  8:58     ` Toke Høiland-Jørgensen
2020-08-21 20:10       ` YiFei Zhu
2020-08-23 18:36         ` Toke Høiland-Jørgensen
2020-08-28 17:00           ` sdf
2020-08-28 20:55             ` Toke Høiland-Jørgensen
2020-08-26  5:36   ` Andrii Nakryiko
2020-08-28 16:59     ` sdf
2020-09-03  5:18       ` Andrii Nakryiko
2020-08-20  9:42 ` [PATCH bpf-next 5/5] selftests/bpf: Test bpftool loading and " YiFei Zhu
2020-08-20 21:15   ` Yonghong Song
2020-08-26  4:00     ` Andrii Nakryiko

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