On Fri, Dec 13, 2024 at 5:08 AM Anton Protopopov <aspsk@xxxxxxxxxxxxx> wrote:
>
> The fd_array attribute of the BPF_PROG_LOAD syscall may contain a set
> of file descriptors: maps or btfs. This field was introduced as a
> sparse array. Introduce a new attribute, fd_array_cnt, which, if
> present, indicates that the fd_array is a continuous array of the
> corresponding length.
>
> If fd_array_cnt is non-zero, then every map in the fd_array will be
> bound to the program, as if it was used by the program. This
> functionality is similar to the BPF_PROG_BIND_MAP syscall, but such
> maps can be used by the verifier during the program load.
>
> Signed-off-by: Anton Protopopov <aspsk@xxxxxxxxxxxxx>
> ---
> include/uapi/linux/bpf.h | 10 ++++
> kernel/bpf/syscall.c | 2 +-
> kernel/bpf/verifier.c | 106 ++++++++++++++++++++++++++++-----
> tools/include/uapi/linux/bpf.h | 10 ++++
> 4 files changed, 112 insertions(+), 16 deletions(-)
>
[...]
> int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u32 uattr_size)
> {
> u64 start_time = ktime_get_ns();
> @@ -22881,7 +22954,6 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u3
> env->insn_aux_data[i].orig_idx = i;
> env->prog = *prog;
> env->ops = bpf_verifier_ops[env->prog->type];
> - env->fd_array = make_bpfptr(attr->fd_array, uattr.is_kernel);
>
> env->allow_ptr_leaks = bpf_allow_ptr_leaks(env->prog->aux->token);
> env->allow_uninit_stack = bpf_allow_uninit_stack(env->prog->aux->token);
> @@ -22904,6 +22976,10 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u3
> if (ret)
> goto err_unlock;
>
> + ret = process_fd_array(env, attr, uattr);
> + if (ret)
> + goto err_release_maps;
I think this should be goto skip_full_check, so that we can finalize
verifier log (you do log an error if fd_array FD is invalid, right?)
If this is the only issue, this can probably be just patched up while applying.
> +
> mark_verifier_state_clean(env);
>
> if (IS_ERR(btf_vmlinux)) {
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index 4162afc6b5d0..2acf9b336371 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -1573,6 +1573,16 @@ union bpf_attr {
> * If provided, prog_flags should have BPF_F_TOKEN_FD flag set.
> */
> __s32 prog_token_fd;
> + /* The fd_array_cnt can be used to pass the length of the
> + * fd_array array. In this case all the [map] file descriptors
> + * passed in this array will be bound to the program, even if
> + * the maps are not referenced directly. The functionality is
> + * similar to the BPF_PROG_BIND_MAP syscall, but maps can be
> + * used by the verifier during the program load. If provided,
> + * then the fd_array[0,...,fd_array_cnt-1] is expected to be
> + * continuous.
> + */
> + __u32 fd_array_cnt;
> };
>
> struct { /* anonymous struct used by BPF_OBJ_* commands */
> --
> 2.34.1
>
>
