On Fri, Jul 22, 2022 at 10:19 AM Roberto Sassu <roberto.sassu@xxxxxxxxxx> wrote:
>
> Introduce bpf_map_get_fd_by_id_opts(), to let the caller pass a
> bpf_get_fd_opts structure with flags set to the permissions necessary to
> perform the operations on the obtained file descriptor.
>
> Don't check FEAT_GET_FD_BY_ID_OPEN_FLAGS, as current kernels already take
> open_flags as last bpf_attr field for this request.
>
> Keep the existing bpf_map_get_fd_by_id(), and call
> bpf_map_get_fd_by_id_opts() with NULL as opts argument, to request
> read-write permissions.
>
> Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
> ---
> tools/lib/bpf/bpf.c | 12 +++++++++++-
> tools/lib/bpf/bpf.h | 2 ++
> tools/lib/bpf/libbpf.map | 1 +
> 3 files changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
> index 9014a61bca83..4b574ad046f3 100644
> --- a/tools/lib/bpf/bpf.c
> +++ b/tools/lib/bpf/bpf.c
> @@ -957,18 +957,28 @@ int bpf_prog_get_fd_by_id(__u32 id)
> return bpf_prog_get_fd_by_id_opts(id, NULL);
> }
>
> -int bpf_map_get_fd_by_id(__u32 id)
> +int bpf_map_get_fd_by_id_opts(__u32 id,
> + const struct bpf_get_fd_opts *opts)
> {
> union bpf_attr attr;
> int fd;
>
> + if (!OPTS_VALID(opts, bpf_get_fd_opts))
> + return libbpf_err(-EINVAL);
> +
> memset(&attr, 0, sizeof(attr));
> attr.map_id = id;
> + attr.open_flags = OPTS_GET(opts, flags, 0);
>
> fd = sys_bpf_fd(BPF_MAP_GET_FD_BY_ID, &attr, sizeof(attr));
> return libbpf_err_errno(fd);
> }
>
> +int bpf_map_get_fd_by_id(__u32 id)
> +{
> + return bpf_map_get_fd_by_id_opts(id, NULL);
> +}
> +
> int bpf_btf_get_fd_by_id(__u32 id)
> {
> union bpf_attr attr;
> diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
> index bc241343a0f9..d4b84d3f7e16 100644
> --- a/tools/lib/bpf/bpf.h
> +++ b/tools/lib/bpf/bpf.h
> @@ -366,6 +366,8 @@ LIBBPF_API int bpf_link_get_next_id(__u32 start_id, __u32 *next_id);
> LIBBPF_API int bpf_prog_get_fd_by_id_opts(__u32 id,
> const struct bpf_get_fd_opts *opts);
> LIBBPF_API int bpf_prog_get_fd_by_id(__u32 id);
> +LIBBPF_API int bpf_map_get_fd_by_id_opts(__u32 id,
> + const struct bpf_get_fd_opts *opts);
> LIBBPF_API int bpf_map_get_fd_by_id(__u32 id);
> LIBBPF_API int bpf_btf_get_fd_by_id(__u32 id);
> LIBBPF_API int bpf_link_get_fd_by_id(__u32 id);
> diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
> index ab818612a585..83dc18b5e5cf 100644
> --- a/tools/lib/bpf/libbpf.map
> +++ b/tools/lib/bpf/libbpf.map
> @@ -365,4 +365,5 @@ LIBBPF_1.0.0 {
> libbpf_bpf_prog_type_str;
> perf_buffer__buffer;
> bpf_prog_get_fd_by_id_opts;
> + bpf_map_get_fd_by_id_opts;
keep in mind that this list is alphabetically sorted
> };
> --
> 2.25.1
>
