On Mon, Dec 10, 2018 at 11:06:43AM -0800, Song Liu wrote:
> This patch adds nr_prog_tags and prog_tags to bpf_prog_info. This is a
> reliable way for user space to get tags of all sub programs. Before this
> patch, user space need to find sub program tags via kallsyms.
>
> This feature will be used in BPF introspection, where user space queries
> information about BPF programs via sys_bpf.
>
> Signed-off-by: Song Liu <songliubrav...@fb.com>
> ---
> include/uapi/linux/bpf.h | 2 ++
> kernel/bpf/syscall.c | 27 +++++++++++++++++++++++++++
> 2 files changed, 29 insertions(+)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 1bee1135866a..368d185aa32f 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -2703,6 +2703,8 @@ struct bpf_prog_info {
> __u32 jited_line_info_cnt;
> __u32 line_info_rec_size;
> __u32 jited_line_info_rec_size;
> + __u32 nr_prog_tags;
> + __aligned_u64 prog_tags;
> } __attribute__((aligned(8)));
>
> struct bpf_map_info {
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 19c88cff7880..df7b1822d585 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -2322,6 +2322,33 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog
> *prog,
> }
> }
>
> + ulen = info.nr_prog_tags;
> + info.nr_prog_tags = prog->aux->func_cnt ? : 1;
> + if (ulen) {
> + if (bpf_dump_raw_ok()) {
> + __u8 __user (*user_prog_tags)[BPF_TAG_SIZE];
> + u32 i;
> +
> + user_prog_tags = u64_to_user_ptr(info.prog_tags);
> + ulen = min_t(u32, info.nr_prog_tags, ulen);
> + if (prog->aux->func_cnt) {
> + for (i = 0; i < ulen; i++) {
> + if (copy_to_user(
> + user_prog_tags[i],
> + prog->aux->func[i]->tag,
> + BPF_TAG_SIZE))
> + return -EFAULT;
> + }
> + } else {
> + if (copy_to_user(user_prog_tags[0],
> + prog->tag, BPF_TAG_SIZE))
> + return -EFAULT;
> + }
> + } else {
> + info.nr_prog_tags = 0;
should be
info.prog_tags = 0;
> + }
> + }
> +
> done:
> if (copy_to_user(uinfo, &info, info_len) ||
> put_user(info_len, &uattr->info.info_len))
> --
> 2.17.1
>
