Commit 243e3005 authored by Roberto Sassu's avatar Roberto Sassu Committed by Andrii Nakryiko
Browse files

libbpf: Introduce bpf_get_fd_by_id_opts and bpf_map_get_fd_by_id_opts() 



Define a new data structure called bpf_get_fd_by_id_opts, with the member
open_flags, to be used by callers of the _opts variants of
bpf_*_get_fd_by_id() to specify the permissions needed for the file
descriptor to be obtained.

Also, introduce bpf_map_get_fd_by_id_opts(), to let the caller pass a
bpf_get_fd_by_id_opts structure.

Finally, 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 (current behavior).

Signed-off-by: default avatarRoberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221006110736.84253-3-roberto.sassu@huaweicloud.com
parent 7a366da2

tools/lib/bpf/bpf.c

+11 −1
Original line number Diff line number Diff line
@@ -948,19 +948,29 @@ int bpf_prog_get_fd_by_id(__u32 id) 
	return libbpf_err_errno(fd);

}



int bpf_map_get_fd_by_id(__u32 id)

int bpf_map_get_fd_by_id_opts(__u32 id,

			      const struct bpf_get_fd_by_id_opts *opts)

{

	const size_t attr_sz = offsetofend(union bpf_attr, open_flags);

	union bpf_attr attr;

	int fd;



	if (!OPTS_VALID(opts, bpf_get_fd_by_id_opts))

		return libbpf_err(-EINVAL);



	memset(&attr, 0, attr_sz);

	attr.map_id = id;

	attr.open_flags = OPTS_GET(opts, open_flags, 0);



	fd = sys_bpf_fd(BPF_MAP_GET_FD_BY_ID, &attr, attr_sz);

	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)

{

	const size_t attr_sz = offsetofend(union bpf_attr, open_flags);

tools/lib/bpf/bpf.h

+10 −0
Original line number Diff line number Diff line
@@ -365,8 +365,18 @@ LIBBPF_API int bpf_prog_get_next_id(__u32 start_id, __u32 *next_id); 
LIBBPF_API int bpf_map_get_next_id(__u32 start_id, __u32 *next_id);

LIBBPF_API int bpf_btf_get_next_id(__u32 start_id, __u32 *next_id);

LIBBPF_API int bpf_link_get_next_id(__u32 start_id, __u32 *next_id);



struct bpf_get_fd_by_id_opts {

	size_t sz; /* size of this struct for forward/backward compatibility */

	__u32 open_flags; /* permissions requested for the operation on fd */

	size_t :0;

};

#define bpf_get_fd_by_id_opts__last_field open_flags



LIBBPF_API int bpf_prog_get_fd_by_id(__u32 id);

LIBBPF_API int bpf_map_get_fd_by_id(__u32 id);

LIBBPF_API int bpf_map_get_fd_by_id_opts(__u32 id,

				const struct bpf_get_fd_by_id_opts *opts);

LIBBPF_API int bpf_btf_get_fd_by_id(__u32 id);

LIBBPF_API int bpf_link_get_fd_by_id(__u32 id);

LIBBPF_API int bpf_obj_get_info_by_fd(int bpf_fd, void *info, __u32 *info_len);

tools/lib/bpf/libbpf.map

+1 −0
Original line number Diff line number Diff line
@@ -371,6 +371,7 @@ LIBBPF_1.0.0 { 


LIBBPF_1.1.0 {

	global:

		bpf_map_get_fd_by_id_opts;

		user_ring_buffer__discard;

		user_ring_buffer__free;

		user_ring_buffer__new;