[PATCH v2 bpf-next 00/14] bpf: cgroup local storage

Roman Gushchin
2018-07-05T20:56:15Z

This patchset implements cgroup local storage for bpf programs.
The main idea is to provide a fast accessible memory for storing
various per-cgroup data, e.g. number of transmitted packets.

Cgroup local storage looks as a special type of map for userspace,
and is accessible using generic bpf maps API for reading and
updating of the data. The (cgroup inode id, attachment type) pair
is used as a map key.

A user can't create new entries or destroy existing entries;
it happens automatically when a user attaches/detaches a bpf program
to a cgroup.

From a bpf program's point of view, cgroup storage is accessible
without lookup using the special get_local_storage() helper function.
It takes a map fd as an argument. It always returns a valid pointer
to the corresponding memory area.
To implement such a lookup-free access a pointer to the cgroup
storage is saved for an attachment of a bpf program to a cgroup,
if required by the program. Before running the program, it's saved
in a special global per-cpu variable, which is accessible from the
get_local_storage() helper.

This patchset implement only cgroup local storage, however the API
is intentionally made extensible to support other local storage types
further: e.g. thread local storage, socket local storage, etc.

Patch (1) adds an ability to charge bpf maps for consuming memory
dynamically.
Patch (2) introduces cgroup storage maps.
Patch (3) implements a mechanism to pass cgroup storage pointer
to a bpf program.
Patch (4) implements allocation/releasing of cgroup local storage
on attaching/detaching of a bpf program to/from a cgroup.
Patch (5) extends bpf_prog_array to store cgroup storage pointers.
Patch (6) introduces BPF_PTR_TO_MAP_VALUE, required to skip
non-necessary NULL-check in bpf programs.
Patch (7) disables creation of maps of cgroup storage maps.
Patch (8) introduces the get_local_storage() helper.
Patch (9) syncs bpf.h to tools/.
Patch (10) adds cgroup storage maps support to bpftool.
Patch (11) adds support for testing programs which are using
cgroup storage without actually attaching them to cgroups.
Patches (12), (13) and (14) are adding necessary tests.

Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Martin KaFai Lau <kafai@fb.com>

v2->v1:
- fixed build issues
- removed explicit rlimit calls in patch 14
- rebased to bpf-next

Roman Gushchin (14):
bpf: add ability to charge bpf maps memory dynamically
bpf: introduce cgroup storage maps
bpf: pass a pointer to a cgroup storage using pcpu variable
bpf: allocate cgroup storage entries on attaching bpf programs
bpf: extend bpf_prog_array to store pointers to the cgroup storage
bpf/verifier: introduce BPF_PTR_TO_MAP_VALUE
bpf: don't allow create maps of cgroup local storages
bpf: introduce the bpf_get_local_storage() helper function
bpf: sync bpf.h to tools/
bpftool: add support for CGROUP_STORAGE maps
bpf/test_run: support cgroup local storage
selftests/bpf: add verifier cgroup storage tests
selftests/bpf: add a cgroup storage test
samples/bpf: extend test_cgrp2_attach2 test to use cgroup storage

include/linux/bpf-cgroup.h | 54 ++++
include/linux/bpf.h | 25 +-
include/linux/bpf_types.h | 3 +
include/uapi/linux/bpf.h | 19 +-
kernel/bpf/Makefile | 1 +
kernel/bpf/cgroup.c | 54 +++-
kernel/bpf/core.c | 77 ++---
kernel/bpf/helpers.c | 20 ++
kernel/bpf/local_storage.c | 369 ++++++++++++++++++++++
kernel/bpf/map_in_map.c | 3 +-
kernel/bpf/syscall.c | 53 +++-
kernel/bpf/verifier.c | 38 ++-
net/bpf/test_run.c | 13 +-
net/core/filter.c | 23 +-
samples/bpf/test_cgrp2_attach2.c | 21 +-
tools/bpf/bpftool/map.c | 1 +
tools/include/uapi/linux/bpf.h | 9 +-
tools/testing/selftests/bpf/Makefile | 4 +-
tools/testing/selftests/bpf/bpf_helpers.h | 2 +
tools/testing/selftests/bpf/test_cgroup_storage.c | 130 ++++++++
tools/testing/selftests/bpf/test_verifier.c | 123 +++++++-
21 files changed, 961 insertions(+), 81 deletions(-)
create mode 100644 kernel/bpf/local_storage.c
create mode 100644 tools/testing/selftests/bpf/test_cgroup_storage.c

--
2.14.4