Hi,
On 15/11/2022 09:08, Zachary Leaf wrote:
Hi,
This RFC proposes changes to the bpf syscall to support propagating user pointers as capabilities in the pure-capability kernel-user ABI (PCuABI). It also includes an approach to supporting the existing aarch64 ABI as a COMPAT layer (compat64).
Since the bpf syscall is multiplexed this RFC changes only the BPF_PROG_LOAD option. The idea is to agree on the general approach and get some feedback here before the remaining options are changed to fully support the syscall.
Since the changes are incomplete, functions in this series suffixed with _fixed will eventually replace the original function it is updating. The originals remain in place for now.
Patches 8 and 9 provide two potential solutions to one problem. I don't know enough about LSMs to decide there so any input there appreciated.
Reading both of them the second solution requires a bit more work upfront from us but I feel that it makes the most sense : no need to update the LSMs and the compat/not compat split is handled right where it happens. I haven't looked into it but maybe other parts of the kernel need something similar already ?
A basic LTP test that only does a bare minimal bpf(BPF_PROG_LOAD...) syscall has been created for this RFC to verify these changes. This also tests the new CHECK_ATTR macro implementation.
Kernel branch available at: https://git.morello-project.org/zdleaf/linux/-/commits/rfc/bpf
LTP test at: https://git.morello-project.org/zdleaf/morello-linux-test-project/-/commits/...
Thanks,
Zach
Overall nothing jumped out to me, it looks pretty good and makes sense to me ! It did help to have read Tudor's patches previously as some things are quite similar between the two. Cheers, Téo
Zachary Leaf (9): arm64: morello: enable eBPF and tracing bpf/net: copy ptrs from user with bpf/sockptr_t bpf: extend bpfptr_t to use pointers bpf: use user pointer types for bpf_attr bpf: add compat64 handling of bpf syscall bpf: make CHECK_ATTR support compat temp for RFC: add padding to BPF_PROG_LOAD bpf/security: update bpf lsm API bpf/security: move lsm hook point
.../morello_transitional_pcuabi_defconfig | 15 ++- include/linux/bpfptr.h | 19 ++++ include/linux/sockptr.h | 9 ++ include/uapi/linux/bpf.h | 55 +++++++++-- kernel/bpf/syscall.c | 95 ++++++++++++++++--- kernel/bpf/verifier.c | 10 +- 6 files changed, 176 insertions(+), 27 deletions(-)
-- 2.34.1
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