[PATCH v6 bpf-next 0/2] security: Propagate caller information in bpf hooks

Blaise Boscaccy
2025-03-08T01:33:39Z

Hello,

While trying to implement an eBPF gatekeeper program, we ran into an
issue whereas the LSM hooks are missing some relevant data.

Certain subcommands passed to the bpf() syscall can be invoked from
either the kernel or userspace. Additionally, some fields in the
bpf_attr struct contain pointers, and depending on where the
subcommand was invoked, they could point to either user or kernel
memory. One example of this is the bpf_prog_load subcommand and its
fd_array. This data is made available and used by the verifier but not
made available to the LSM subsystem. This patchset simply exposes that
information to applicable LSM hooks.

Change list:
- v5 -> v6
- fix regression caused by is_kernel renaming
- simplify test logic
- v4 -> v5
- merge v4 selftest breakout patch back into a single patch
- change "is_kernel" to "kernel"
- add selftest using new kernel flag
- v3 -> v4
- split out selftest changes into a separate patch
- v2 -> v3
- reorder params so that the new boolean flag is the last param
- fixup function signatures in bpf selftests
- v1 -> v2
- Pass a boolean flag in lieu of bpfptr_t

Revisions:
- v5
https://lore.kernel.org/bpf/20250307213651.3065714-1-bboscaccy@linux.microsoft.com/
- v4
https://lore.kernel.org/bpf/20250304203123.3935371-1-bboscaccy@linux.microsoft.com/
- v3
https://lore.kernel.org/bpf/20250303222416.3909228-1-bboscaccy@linux.microsoft.com/
- v2
https://lore.kernel.org/bpf/20250228165322.3121535-1-bboscaccy@linux.microsoft.com/
- v1
https://lore.kernel.org/bpf/20250226003055.1654837-1-bboscaccy@linux.microsoft.com/

Blaise Boscaccy (2):
security: Propagate caller information in bpf hooks
selftests/bpf: Add a kernel flag test for LSM bpf hook

include/linux/lsm_hook_defs.h | 6 +--
include/linux/security.h | 12 +++---
kernel/bpf/syscall.c | 10 ++---
security/security.c | 15 ++++---
security/selinux/hooks.c | 6 +--
.../selftests/bpf/prog_tests/kernel_flag.c | 43 +++++++++++++++++++
.../selftests/bpf/progs/rcu_read_lock.c | 3 +-
.../bpf/progs/test_cgroup1_hierarchy.c | 4 +-
.../selftests/bpf/progs/test_kernel_flag.c | 28 ++++++++++++
.../bpf/progs/test_kfunc_dynptr_param.c | 6 +--
.../selftests/bpf/progs/test_lookup_key.c | 2 +-
.../selftests/bpf/progs/test_ptr_untrusted.c | 2 +-
.../bpf/progs/test_task_under_cgroup.c | 2 +-
.../bpf/progs/test_verify_pkcs7_sig.c | 2 +-
14 files changed, 108 insertions(+), 33 deletions(-)
create mode 100644 tools/testing/selftests/bpf/prog_tests/kernel_flag.c
create mode 100644 tools/testing/selftests/bpf/progs/test_kernel_flag.c

--
2.48.1