Commit 9406b485 authored by Yonghong Song's avatar Yonghong Song Committed by Alexei Starovoitov

tools/bpftool: Add bpf_iter support for bptool

Currently, only one command is supported
  bpftool iter pin <bpf_prog.o> <path>

It will pin the trace/iter bpf program in
the object file <bpf_prog.o> to the <path>
where <path> should be on a bpffs mount.

For example,
  $ bpftool iter pin ./bpf_iter_ipv6_route.o \
    /sys/fs/bpf/my_route
User can then do a `cat` to print out the results:
  $ cat /sys/fs/bpf/my_route
    fe800000000000000000000000000000 40 00000000000000000000000000000000 ...
    00000000000000000000000000000000 00 00000000000000000000000000000000 ...
    00000000000000000000000000000001 80 00000000000000000000000000000000 ...
    fe800000000000008c0162fffebdfd57 80 00000000000000000000000000000000 ...
    ff000000000000000000000000000000 08 00000000000000000000000000000000 ...
    00000000000000000000000000000000 00 00000000000000000000000000000000 ...

The implementation for ipv6_route iterator is in one of subsequent
patches.

This patch also added BPF_LINK_TYPE_ITER to link query.

In the future, we may add additional parameters to pin command
by parameterizing the bpf iterator. For example, a map_id or pid
may be added to let bpf program only traverses a single map or task,
similar to kernel seq_file single_open().

We may also add introspection command for targets/iterators by
leveraging the bpf_iter itself.
Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200509175920.2477247-1-yhs@fb.com
parent 5fbc2208
============
bpftool-iter
============
-------------------------------------------------------------------------------
tool to create BPF iterators
-------------------------------------------------------------------------------
:Manual section: 8
SYNOPSIS
========
**bpftool** [*OPTIONS*] **iter** *COMMAND*
*COMMANDS* := { **pin** | **help** }
ITER COMMANDS
===================
| **bpftool** **iter pin** *OBJ* *PATH*
| **bpftool** **iter help**
|
| *OBJ* := /a/file/of/bpf_iter_target.o
DESCRIPTION
===========
**bpftool iter pin** *OBJ* *PATH*
A bpf iterator combines a kernel iterating of
particular kernel data (e.g., tasks, bpf_maps, etc.)
and a bpf program called for each kernel data object
(e.g., one task, one bpf_map, etc.). User space can
*read* kernel iterator output through *read()* syscall.
The *pin* command creates a bpf iterator from *OBJ*,
and pin it to *PATH*. The *PATH* should be located
in *bpffs* mount. It must not contain a dot
character ('.'), which is reserved for future extensions
of *bpffs*.
User can then *cat PATH* to see the bpf iterator output.
**bpftool iter help**
Print short help message.
OPTIONS
=======
-h, --help
Print short generic help message (similar to **bpftool help**).
-V, --version
Print version number (similar to **bpftool version**).
-d, --debug
Print all logs available, even debug-level information. This
includes logs from libbpf as well as from the verifier, when
attempting to load programs.
EXAMPLES
========
**# bpftool iter pin bpf_iter_netlink.o /sys/fs/bpf/my_netlink**
::
Create a file-based bpf iterator from bpf_iter_netlink.o and pin it
to /sys/fs/bpf/my_netlink
SEE ALSO
========
**bpf**\ (2),
**bpf-helpers**\ (7),
**bpftool**\ (8),
**bpftool-prog**\ (8),
**bpftool-map**\ (8),
**bpftool-link**\ (8),
**bpftool-cgroup**\ (8),
**bpftool-feature**\ (8),
**bpftool-net**\ (8),
**bpftool-perf**\ (8),
**bpftool-btf**\ (8)
**bpftool-gen**\ (8)
**bpftool-struct_ops**\ (8)
......@@ -610,6 +610,19 @@ _bpftool()
;;
esac
;;
iter)
case $command in
pin)
_filedir
return 0
;;
*)
[[ $prev == $object ]] && \
COMPREPLY=( $( compgen -W 'pin help' \
-- "$cur" ) )
;;
esac
;;
map)
local MAP_TYPE='id pinned name'
case $command in
......
// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
// Copyright (C) 2020 Facebook
#define _GNU_SOURCE
#include <linux/err.h>
#include <bpf/libbpf.h>
#include "main.h"
static int do_pin(int argc, char **argv)
{
const char *objfile, *path;
struct bpf_program *prog;
struct bpf_object *obj;
struct bpf_link *link;
int err;
if (!REQ_ARGS(2))
usage();
objfile = GET_ARG();
path = GET_ARG();
obj = bpf_object__open(objfile);
if (IS_ERR(obj)) {
p_err("can't open objfile %s", objfile);
return -1;
}
err = bpf_object__load(obj);
if (err) {
p_err("can't load objfile %s", objfile);
goto close_obj;
}
prog = bpf_program__next(NULL, obj);
if (!prog) {
p_err("can't find bpf program in objfile %s", objfile);
goto close_obj;
}
link = bpf_program__attach_iter(prog, NULL);
if (IS_ERR(link)) {
err = PTR_ERR(link);
p_err("attach_iter failed for program %s",
bpf_program__name(prog));
goto close_obj;
}
err = mount_bpffs_for_pin(path);
if (err)
goto close_link;
err = bpf_link__pin(link, path);
if (err) {
p_err("pin_iter failed for program %s to path %s",
bpf_program__name(prog), path);
goto close_link;
}
close_link:
bpf_link__destroy(link);
close_obj:
bpf_object__close(obj);
return err;
}
static int do_help(int argc, char **argv)
{
fprintf(stderr,
"Usage: %s %s pin OBJ PATH\n"
" %s %s help\n"
"\n",
bin_name, argv[-2], bin_name, argv[-2]);
return 0;
}
static const struct cmd cmds[] = {
{ "help", do_help },
{ "pin", do_pin },
{ 0 }
};
int do_iter(int argc, char **argv)
{
return cmd_select(cmds, argc, argv, do_help);
}
......@@ -16,6 +16,7 @@ static const char * const link_type_name[] = {
[BPF_LINK_TYPE_RAW_TRACEPOINT] = "raw_tracepoint",
[BPF_LINK_TYPE_TRACING] = "tracing",
[BPF_LINK_TYPE_CGROUP] = "cgroup",
[BPF_LINK_TYPE_ITER] = "iter",
};
static int link_parse_fd(int *argc, char ***argv)
......
......@@ -59,7 +59,7 @@ static int do_help(int argc, char **argv)
" %s batch file FILE\n"
" %s version\n"
"\n"
" OBJECT := { prog | map | link | cgroup | perf | net | feature | btf | gen | struct_ops }\n"
" OBJECT := { prog | map | link | cgroup | perf | net | feature | btf | gen | struct_ops | iter }\n"
" " HELP_SPEC_OPTIONS "\n"
"",
bin_name, bin_name, bin_name);
......@@ -224,6 +224,7 @@ static const struct cmd cmds[] = {
{ "btf", do_btf },
{ "gen", do_gen },
{ "struct_ops", do_struct_ops },
{ "iter", do_iter },
{ "version", do_version },
{ 0 }
};
......
......@@ -199,6 +199,7 @@ int do_feature(int argc, char **argv);
int do_btf(int argc, char **argv);
int do_gen(int argc, char **argv);
int do_struct_ops(int argc, char **argv);
int do_iter(int argc, char **argv);
int parse_u32_arg(int *argc, char ***argv, __u32 *val, const char *what);
int prog_parse_fd(int *argc, char ***argv);
......
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