Commit 27b3f705 authored by Quentin Monnet's avatar Quentin Monnet Committed by Daniel Borkmann
Browse files

bpftool: Add feature list (prog/map/link/attach types, helpers) 



Add a "bpftool feature list" subcommand to list BPF "features".
Contrarily to "bpftool feature probe", this is not about the features
available on the system. Instead, it lists all features known to bpftool
from compilation time; in other words, all program, map, attach, link
types known to the libbpf version in use, and all helpers found in the
UAPI BPF header.

The first use case for this feature is bash completion: running the
command provides a list of types that can be used to produce the list of
candidate map types, for example.

Now that bpftool uses "standard" names provided by libbpf for the
program, map, link, and attach types, having the ability to list these
types and helpers could also be useful in scripts to loop over existing
items.

Sample output:

    # bpftool feature list prog_types | grep -vw unspec | head -n 6
    socket_filter
    kprobe
    sched_cls
    sched_act
    tracepoint
    xdp

    # bpftool -p feature list map_types | jq '.[1]'
    "hash"

    # bpftool feature list attach_types | grep '^cgroup_'
    cgroup_inet_ingress
    cgroup_inet_egress
    [...]
    cgroup_inet_sock_release

    # bpftool feature list helpers | grep -vw bpf_unspec | wc -l
    207

The "unspec" types and helpers are not filtered out by bpftool, so as to
remain closer to the enums, and to preserve the indices in the JSON
arrays (e.g. "hash" at index 1 == BPF_MAP_TYPE_HASH in map types list).

Signed-off-by: default avatarQuentin Monnet <quentin@isovalent.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarDaniel Müller <deso@posteo.net>
Link: https://lore.kernel.org/bpf/20220629203637.138944-2-quentin@isovalent.com
parent b0cbd615

tools/bpf/bpftool/Documentation/bpftool-feature.rst

+12 −0
Original line number Diff line number Diff line
@@ -24,9 +24,11 @@ FEATURE COMMANDS 
================



|	**bpftool** **feature probe** [*COMPONENT*] [**full**] [**unprivileged**] [**macros** [**prefix** *PREFIX*]]

|	**bpftool** **feature list** *GROUP*

|	**bpftool** **feature help**

|

|	*COMPONENT* := { **kernel** | **dev** *NAME* }

|	*GROUP* := { **prog_types** | **map_types** | **attach_types** | **link_types** | **helpers** }



DESCRIPTION

===========
@@ -70,6 +72,16 @@ DESCRIPTION 
		  The keywords **full**, **macros** and **prefix** have the

		  same role as when probing the kernel.



	**bpftool feature list** *GROUP*

		  List items known to bpftool. These can be BPF program types

		  (**prog_types**), BPF map types (**map_types**), attach types

		  (**attach_types**), link types (**link_types**), or BPF helper

		  functions (**helpers**). The command does not probe the system, but

		  simply lists the elements that bpftool knows from compilation time,

		  as provided from libbpf (for all object types) or from the BPF UAPI

		  header (list of helpers). This can be used in scripts to iterate over

		  BPF types or helpers.



	**bpftool feature help**

		  Print short help message.

tools/bpf/bpftool/bash-completion/bpftool

+6 −1
Original line number Diff line number Diff line
@@ -1175,9 +1175,14 @@ _bpftool() 
                    _bpftool_once_attr 'full unprivileged'

                    return 0

                    ;;

                list)

                    [[ $prev != "$command" ]] && return 0

                    COMPREPLY=( $( compgen -W 'prog_types map_types \

                        attach_types link_types helpers' -- "$cur" ) )

                    ;;

                *)

                    [[ $prev == $object ]] && \

                        COMPREPLY=( $( compgen -W 'help probe' -- "$cur" ) )

                        COMPREPLY=( $( compgen -W 'help list probe' -- "$cur" ) )

                    ;;

            esac

            ;;

tools/bpf/bpftool/feature.c

+55 −0
Original line number Diff line number Diff line
@@ -1258,6 +1258,58 @@ static int do_probe(int argc, char **argv) 
	return 0;

}



static const char *get_helper_name(unsigned int id)

{

	if (id >= ARRAY_SIZE(helper_name))

		return NULL;



	return helper_name[id];

}



static int do_list(int argc, char **argv)

{

	const char *(*get_name)(unsigned int id);

	unsigned int id = 0;



	if (argc < 1)

		usage();



	if (is_prefix(*argv, "prog_types")) {

		get_name = (const char *(*)(unsigned int))libbpf_bpf_prog_type_str;

	} else if (is_prefix(*argv, "map_types")) {

		get_name = (const char *(*)(unsigned int))libbpf_bpf_map_type_str;

	} else if (is_prefix(*argv, "attach_types")) {

		get_name = (const char *(*)(unsigned int))libbpf_bpf_attach_type_str;

	} else if (is_prefix(*argv, "link_types")) {

		get_name = (const char *(*)(unsigned int))libbpf_bpf_link_type_str;

	} else if (is_prefix(*argv, "helpers")) {

		get_name = get_helper_name;

	} else {

		p_err("expected 'prog_types', 'map_types', 'attach_types', 'link_types' or 'helpers', got: %s", *argv);

		return -1;

	}



	if (json_output)

		jsonw_start_array(json_wtr);	/* root array */



	while (true) {

		const char *name;



		name = get_name(id++);

		if (!name)

			break;

		if (json_output)

			jsonw_string(json_wtr, name);

		else

			printf("%s\n", name);

	}



	if (json_output)

		jsonw_end_array(json_wtr);	/* root array */



	return 0;

}



static int do_help(int argc, char **argv)

{

	if (json_output) {
@@ -1267,9 +1319,11 @@ static int do_help(int argc, char **argv) 


	fprintf(stderr,

		"Usage: %1$s %2$s probe [COMPONENT] [full] [unprivileged] [macros [prefix PREFIX]]\n"

		"       %1$s %2$s list GROUP\n"

		"       %1$s %2$s help\n"

		"\n"

		"       COMPONENT := { kernel | dev NAME }\n"

		"       GROUP := { prog_types | map_types | attach_types | link_types | helpers }\n"

		"       " HELP_SPEC_OPTIONS " }\n"

		"",

		bin_name, argv[-2]);
@@ -1279,6 +1333,7 @@ static int do_help(int argc, char **argv) 


static const struct cmd cmds[] = {

	{ "probe",	do_probe },

	{ "list",	do_list },

	{ "help",	do_help },

	{ 0 }

};