This series implements new lsm flavor for attaching per-cgroup programs to existing lsm hooks. The cgroup is taken out of 'current', unless the first argument of the hook is 'struct socket'. In this case, the cgroup association is taken out of socket. The attachment looks like a regular per-cgroup attachment: we add new BPF_LSM_CGROUP attach type which, together with attach_btf_id, signals per-cgroup lsm. Behind the scenes, we allocate trampoline shim program and attach to lsm. This program looks up cgroup from current/socket and runs cgroup's effective prog array. The rest of the per-cgroup BPF stays the same: hierarchy, local storage, retval conventions (return 1 == success). Current limitations: * haven't considered sleepable bpf; can be extended later on * not sure the verifier does the right thing with null checks; see latest selftest for details * total of 10 (global) per-cgroup LSM attach points; this bloats bpf_cgroup a bit Cc: ast@xxxxxxxxxx Cc: daniel@xxxxxxxxxxxxx Cc: kafai@xxxxxx Cc: kpsingh@xxxxxxxxxx v3: - add BPF_LSM_CGROUP to bpftool - use simple int instead of refcnt_t (to avoid use-after-free false positive) v2: - addressed build bot failures Stanislav Fomichev (7): bpf: add bpf_func_t and trampoline helpers bpf: per-cgroup lsm flavor bpf: minimize number of allocated lsm slots per program bpf: allow writing to a subset of sock fields from lsm progtype libbpf: add lsm_cgoup_sock type selftests/bpf: lsm_cgroup functional test selftests/bpf: verify lsm_cgroup struct sock access include/linux/bpf-cgroup-defs.h | 8 + include/linux/bpf.h | 24 +- include/linux/bpf_lsm.h | 8 + include/uapi/linux/bpf.h | 1 + kernel/bpf/bpf_lsm.c | 147 ++++++++++++ kernel/bpf/btf.c | 11 + kernel/bpf/cgroup.c | 210 ++++++++++++++++-- kernel/bpf/syscall.c | 10 + kernel/bpf/trampoline.c | 205 ++++++++++++++--- kernel/bpf/verifier.c | 4 +- tools/bpf/bpftool/common.c | 1 + tools/include/uapi/linux/bpf.h | 1 + tools/lib/bpf/libbpf.c | 2 + .../selftests/bpf/prog_tests/lsm_cgroup.c | 158 +++++++++++++ .../testing/selftests/bpf/progs/lsm_cgroup.c | 94 ++++++++ tools/testing/selftests/bpf/test_verifier.c | 54 ++++- .../selftests/bpf/verifier/lsm_cgroup.c | 34 +++ 17 files changed, 914 insertions(+), 58 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/lsm_cgroup.c create mode 100644 tools/testing/selftests/bpf/progs/lsm_cgroup.c create mode 100644 tools/testing/selftests/bpf/verifier/lsm_cgroup.c -- 2.35.1.1178.g4f1659d476-goog
