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linux/kernel/bpf
Andrii Nakryiko 0ba971511d bpf: enforce types for __arg_ctx-tagged arguments in global subprogs
Add enforcement of expected types for context arguments tagged with
arg:ctx (__arg_ctx) tag.

First, any program type will accept generic `void *` context type when
combined with __arg_ctx tag.

Besides accepting "canonical" struct names and `void *`, for a bunch of
program types for which program context is actually a named struct, we
allows a bunch of pragmatic exceptions to match real-world and expected
usage:

  - for both kprobes and perf_event we allow `bpf_user_pt_regs_t *` as
    canonical context argument type, where `bpf_user_pt_regs_t` is a
    *typedef*, not a struct;
  - for kprobes, we also always accept `struct pt_regs *`, as that's what
    actually is passed as a context to any kprobe program;
  - for perf_event, we resolve typedefs (unless it's `bpf_user_pt_regs_t`)
    down to actual struct type and accept `struct pt_regs *`, or
    `struct user_pt_regs *`, or `struct user_regs_struct *`, depending
    on the actual struct type kernel architecture points `bpf_user_pt_regs_t`
    typedef to; otherwise, canonical `struct bpf_perf_event_data *` is
    expected;
  - for raw_tp/raw_tp.w programs, `u64/long *` are accepted, as that's
    what's expected with BPF_PROG() usage; otherwise, canonical
    `struct bpf_raw_tracepoint_args *` is expected;
  - tp_btf supports both `struct bpf_raw_tracepoint_args *` and `u64 *`
    formats, both are coded as expections as tp_btf is actually a TRACING
    program type, which has no canonical context type;
  - iterator programs accept `struct bpf_iter__xxx *` structs, currently
    with no further iterator-type specific enforcement;
  - fentry/fexit/fmod_ret/lsm/struct_ops all accept `u64 *`;
  - classic tracepoint programs, as well as syscall and freplace
    programs allow any user-provided type.

In all other cases kernel will enforce exact match of struct name to
expected canonical type. And if user-provided type doesn't match that
expectation, verifier will emit helpful message with expected type name.

Note a bit unnatural way the check is done after processing all the
arguments. This is done to avoid conflict between bpf and bpf-next
trees. Once trees converge, a small follow up patch will place a simple
btf_validate_prog_ctx_type() check into a proper ARG_PTR_TO_CTX branch
(which bpf-next tree patch refactored already), removing duplicated
arg:ctx detection logic.

Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240118033143.3384355-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-01-17 20:20:06 -08:00
..
preload
arraymap.c Revert BPF token-related functionality 2023-12-19 08:23:03 -08:00
bloom_filter.c
bpf_cgrp_storage.c bpf: Enable bpf_cgrp_storage for cgroup1 non-attach case 2023-12-08 17:08:18 -08:00
bpf_inode_storage.c
bpf_iter.c
bpf_local_storage.c
bpf_lru_list.c
bpf_lru_list.h
bpf_lsm.c Revert BPF token-related functionality 2023-12-19 08:23:03 -08:00
bpf_struct_ops_types.h
bpf_struct_ops.c x86/cfi,bpf: Fix bpf_struct_ops CFI 2023-12-15 16:25:55 -08:00
bpf_task_storage.c
btf.c bpf: enforce types for __arg_ctx-tagged arguments in global subprogs 2024-01-17 20:20:06 -08:00
cgroup_iter.c
cgroup.c Revert BPF token-related functionality 2023-12-19 08:23:03 -08:00
core.c Revert BPF token-related functionality 2023-12-19 08:23:03 -08:00
cpumap.c
cpumask.c bpf: Fix dtor CFI 2023-12-15 16:25:55 -08:00
devmap.c
disasm.c
disasm.h
dispatcher.c bpf: Use arch_bpf_trampoline_size 2023-12-06 17:17:20 -08:00
hashtab.c Networking changes for 6.8. 2024-01-11 10:07:29 -08:00
helpers.c Revert BPF token-related functionality 2023-12-19 08:23:03 -08:00
inode.c bpf: Re-support uid and gid when mounting bpffs 2023-12-21 14:24:30 +01:00
Kconfig
link_iter.c
local_storage.c
log.c bpf: emit more dynptr information in verifier log 2023-12-11 19:21:22 -08:00
lpm_trie.c
Makefile Revert BPF token-related functionality 2023-12-19 08:23:03 -08:00
map_in_map.c bpf: Optimize the free of inner map 2023-12-04 17:50:26 -08:00
map_in_map.h bpf: Add map and need_defer parameters to .map_fd_put_ptr() 2023-12-04 17:50:26 -08:00
map_iter.c
memalloc.c bpf: Remove unnecessary cpu == 0 check in memalloc 2024-01-04 10:18:14 -08:00
mmap_unlock_work.h
mprog.c
net_namespace.c
offload.c
percpu_freelist.c
percpu_freelist.h
prog_iter.c
queue_stack_maps.c
reuseport_array.c
ringbuf.c
stackmap.c
syscall.c bpf: Fix re-attachment branch in bpf_tracing_prog_attach 2024-01-04 20:40:19 -08:00
sysfs_btf.c
task_iter.c bpf: bpf_iter_task_next: use next_task(kit->task) rather than next_task(kit->pos) 2023-11-19 11:43:44 -08:00
tcx.c
tnum.c bpf: simplify tnum output if a fully known constant 2023-12-02 11:36:51 -08:00
trampoline.c bpf: Use arch_bpf_trampoline_size 2023-12-06 17:17:20 -08:00
verifier.c bpf: Reject variable offset alu on PTR_TO_FLOW_KEYS 2024-01-16 17:12:29 +01:00