linux-morello September 2023

linux-morello@op-lists.linaro.org

7 participants
13 discussions

[PATCH 0/2] Refactoring capability stack manipulation in binfmt_elf

by Kevin Brodsky

Hi, This short series refactors the way pointers to the stack are manipulated in binfmt_elf. The changes are generic and arguably improve binfmt_elf, but the main objective is to eliminate unnecessary creation of capabilities in PCuABI (through calls to uaddr_to_user_ptr_safe()). This is done by using an actual user pointer to keep track of the current position on the stack, and writing all data through that pointer, instead of using an addresss and creating a new user pointer for every access. This is what patch 1 does. Patch 2 simplifies the elf_stack_put_user* macros we previously introduced, as we do not need them to do something special in PCuABI any more. This series should help with further work on restricting initial capabilities [1]. It does not have any user-visible effect itself however. The new "root stack capability" is still unrestricted, but the fact that all capabilities to the stack are derived from it means that any later narrowing of its bounds or permissions will automatically propagate. Note that these changes are mostly orthogonal to Téo's series [2] that partially addresses [1]; it just means that using uaddr_to_user_ptr_safe() is no longer necessary to derive the argv / envp capabilities. Review branch: https://git.morello-project.org/kbrodsky-arm/linux/-/commits/morello/binfmt… Thanks, Kevin [1] https://git.morello-project.org/morello/kernel/linux/-/issues/19 [2] https://op-lists.linaro.org/archives/list/linux-morello@op-lists.linaro.org… Kevin Brodsky (2): fs/binfmt_elf: Improve SP manipulation in PCuABI fs/binfmt_elf: Simplify elf_stack_put_user* fs/binfmt_elf.c | 85 +++++++++++++++++++++++------------------- fs/compat_binfmt_elf.c | 9 +---- include/linux/elf.h | 12 +----- 3 files changed, 48 insertions(+), 58 deletions(-) -- 2.38.1

7 months, 4 weeks

[PATCH 00/10] update bpf syscall for PCuABI/compat64

by Zachary Leaf

Hi, After getting side tracked by eBPF libraries/tools (libbpf/bpftool) and kselftest cross-compilation, here's the core kernel changes following on from the RFC[1] posted late last year. The bpf syscall is updated to propagate user pointers as capabilities in the pure-capability kernel-user ABI (PCuABI). It also includes an approach to support the existing aarch64 ABI as a compatibility layer (compat64). One complication here is from the fact this syscall supports many multiplexed sub-commands, some of which are themselves multiplexed with a number of nested multiplexed options. A further complication is that the existing syscall uses a trick of storing user pointers as u64 to avoid needing a compat handler for 32-bit systems (see patch 3). To retain compatibility with the aarch64 ABI and add Morello support, a compat layer is added here only for the compat64 case, guarded by #ifdef CONFIG_COMPAT64. Normal compat32 operation is therefore unchanged. Compared to the original RFC, inbound (userspace->kernel) conversion between compat64/native struct layouts is now handled upfront. This minimises changes to subcommand handlers. Some subcommands require conversion back out to userspace and that is by necessity handled where it occurs. Patch 1 is not essential to this series but it's a nice debug feature to have and works[2]. It enables BPF_PROG_TYPE_TRACEPOINT which many eBPF kselftests use. Patch 2 is required setup for the rest of the patches. Patches 3-8 implement the core compat64 handling. Each commit compiles cleanly but relevant parts will be broken inbetween. They're split mainly to make review here easier. Patch 9 fixes a check to also check configs passed in via compat64. Patch 10 finally enables capabilities in the kernel. Testing wise, see associated LTP changes below which will be posted to linux-morello-ltp mailing list. The eBPF LTP tests are fairly minimal and test only a small part of the changes here. There's a new test to test patch 9. The kernel kselftests contain much more extensive eBPF tests. The kselftests have been used to test many parts of the compat64 handling but overall more work needs to be done here: a) enable cross-compilation for purecap as well as x86->aarch64 b) replace ptr_to_u64() with casts to uintptr_t in tests b) general libbpf/bpftool enablement and fixes since many tests rely on this c) CONFIG_DEBUG_INFO_BTF required for many tests but this requires the build system to have a recent version of pahole tool Next steps once we have the core kernel support is porting libbpf and bpftool for purecap plus work on enabling kselftests as above. Kernel branch available at: https://git.morello-project.org/zdleaf/linux/-/tree/morello/bpf Associated LTP test/changes at: https://git.morello-project.org/zdleaf/morello-linux-test-project/-/tree/mo… Thanks, Zach [1] [RFC PATCH 0/9] update bpf syscall for PCuABI/compat64 https://op-lists.linaro.org/archives/list/linux-morello@op-lists.linaro.org… [2] [PATCH v3 0/5] Restore syscall tracing on Morello https://op-lists.linaro.org/archives/list/linux-morello@op-lists.linaro.org… Zachary Leaf (10): arm64: morello: enable syscall tracing bpf/net: copy ptrs from user with bpf/sockptr_t bpf: compat64: add handler and convert bpf_attr in bpf: compat64: bpf_attr convert out bpf: compat64: handle bpf_btf_info bpf: compat64: handle bpf_prog_info bpf: compat64: handle bpf_map_info bpf: compat64: handle bpf_link_info bpf: compat64: support CHECK_ATTR macro bpf: use user pointer types in uAPI structs .../morello_transitional_pcuabi_defconfig | 2 +- arch/arm64/kernel/sys_compat64.c | 4 + drivers/media/rc/bpf-lirc.c | 7 +- include/linux/bpf_compat.h | 413 ++++++ include/linux/bpfptr.h | 18 +- include/linux/sockptr.h | 9 + include/uapi/linux/bpf.h | 94 +- kernel/bpf/bpf_iter.c | 2 +- kernel/bpf/btf.c | 97 +- kernel/bpf/cgroup.c | 10 +- kernel/bpf/hashtab.c | 13 +- kernel/bpf/net_namespace.c | 7 +- kernel/bpf/offload.c | 2 +- kernel/bpf/syscall.c | 1136 +++++++++++++---- kernel/bpf/verifier.c | 2 +- kernel/trace/bpf_trace.c | 6 +- net/bpf/bpf_dummy_struct_ops.c | 3 +- net/bpf/test_run.c | 32 +- net/core/sock_map.c | 7 +- 19 files changed, 1534 insertions(+), 330 deletions(-) create mode 100644 include/linux/bpf_compat.h -- 2.34.1

7 months, 4 weeks

[PATCH v5 0/7] Add explicit capability checking

by Luca Vizzarro

Hello! Here is patch series v5 incoming for the explicit capability checking series for issue #7[1]. This patch series can be found on my fork[2]. Kind regards, Luca [1] https://git.morello-project.org/morello/kernel/linux/-/issues/7 [2] https://git.morello-project.org/Sevenarth/linux/-/commits/morello/gup-check… v5: - rephrased commit descriptions - changed explicit checks for the USB code to be performed only when performing DMA transfers v4: - rebased onto morello/next - rephrased commit descriptions and notes left in the code - signature of first_iovec_segment has been updated to return a pointer instead of an address and the appropriate changes have been made - read+write checks have been combined together in the same if statement - unlikely check has been removed where appropriate - the USB User Request Block buffer is now checked against both write and read permissions according to the transfer direction as indicated by is_in - a leftover from v2 at io_uring/rsrc.c:1249 has been reverted back to original v3: - rebased onto morello/next - amended commit description for "gup: Add explicit capability checks" - refactored mm/gup.c - refactored lib/iov_iter.c - removed bpf patch - moved USB Request Block explicit check to proc_do_submiturb - removed explicit check in get_futex_key - changed prototype of io_uring_cmd_import_fixed and io_import_fixed to use a pointer type and adjusted the relevant castings - fixed io_uring_cmd_import_fixed prototype for !defined(CONFIG_IO_URING) - refactored explicit check in io_uring/kbuf.c:io_register_pbuf_ring(..) - removed explicit check from io_uring/kbuf.c:io_add_buffers(..) - rephrased the no explicit check needed note in io_sqe_buffer_register - reverted "struct io_mapped_ubuf" to use u64 - removed explicit check from io_uring_cmd_prep - updated TODO for the NVMe driver Luca Vizzarro (7): gup: Add explicit capability checks iov_iter: Add explicit capability checks usb: core: Fix copy of URB from userspace usb: core: Add explicit capability checks futex: Add explicit capability checks io_uring: Add explicit capability checks nvme: Add TODO for PCuABI implementation drivers/nvme/host/ioctl.c | 1 + drivers/usb/core/devio.c | 10 ++++++++-- include/linux/io_uring.h | 6 +++--- include/linux/pagemap.h | 2 +- io_uring/kbuf.c | 26 +++++++++++++------------- io_uring/net.c | 3 +-- io_uring/rsrc.c | 14 ++++++++++++-- io_uring/rsrc.h | 2 +- io_uring/rw.c | 3 +-- io_uring/uring_cmd.c | 2 +- kernel/futex/core.c | 11 ++++++++--- lib/iov_iter.c | 31 ++++++++++++++++++++++++------- mm/gup.c | 6 ++++-- 13 files changed, 78 insertions(+), 39 deletions(-) -- 2.34.1

8 months, 1 week

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linux-morello September 2023