[PATCH bpf-next v1 16/19] tools/bpftool: add bpf_iter support for bptool

Yonghong Song
2020-04-27T20:13:18Z

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.

Signed-off-by: Yonghong Song <yhs@fb.com>
---
.../bpftool/Documentation/bpftool-iter.rst | 71 ++++++++++++++++
tools/bpf/bpftool/bash-completion/bpftool | 13 +++
tools/bpf/bpftool/iter.c | 84 +++++++++++++++++++
tools/bpf/bpftool/main.c | 3 +-
tools/bpf/bpftool/main.h | 1 +
5 files changed, 171 insertions(+), 1 deletion(-)
create mode 100644 tools/bpf/bpftool/Documentation/bpftool-iter.rst
create mode 100644 tools/bpf/bpftool/iter.c

diff --git a/tools/bpf/bpftool/Documentation/bpftool-iter.rst b/tools/bpf/bpftool/Documentation/bpftool-iter.rst
new file mode 100644
index 000000000000..1997a6bac4a0
--- /dev/null
+++ b/tools/bpf/bpftool/Documentation/bpftool-iter.rst
@@ -0,0 +1,71 @@
+============
+bpftool-iter
+============
+-------------------------------------------------------------------------------
+tool to create BPF iterators
+-------------------------------------------------------------------------------
+
+:Manual section: 8
+
+SYNOPSIS
+========
+
+ **bpftool** [*OPTIONS*] **iter** *COMMAND*
+
+ *COMMANDS* := { **pin** | **help** }
+
+STRUCT_OPS COMMANDS
+===================
+
+| **bpftool** **iter pin** *OBJ* *PATH*
+| **bpftool** **struct_ops help**
+|
+| *OBJ* := /a/file/of/bpf_iter_target.o
+
+
+DESCRIPTION
+===========
+ **bpftool iter pin** *OBJ* *PATH*
+ Create a bpf iterator from *OBJ*, and pin it to
+ *PATH*. The *PATH* should be located in *bpffs* mount.
+
+ **bpftool struct_ops 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-cgroup**\ (8),
+ **bpftool-feature**\ (8),
+ **bpftool-net**\ (8),
+ **bpftool-perf**\ (8),
+ **bpftool-btf**\ (8)
+ **bpftool-gen**\ (8)
+ **bpftool-struct_ops**\ (8)
diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool
index 45ee99b159e2..17a81695da0f 100644
--- a/tools/bpf/bpftool/bash-completion/bpftool
+++ b/tools/bpf/bpftool/bash-completion/bpftool
@@ -604,6 +604,19 @@ _bpftool()
;;
esac
;;
+ iter)
+ case $command in
+ pin)
+ _filedir
+ return 0
+ ;;
+ *)
+ [[ $prev == $object ]] && \
+ COMPREPLY=( $( compgen -W 'help' \
+ -- "$cur" ) )
+ ;;
+ esac
+ ;;
map)
local MAP_TYPE='id pinned name'
case $command in
diff --git a/tools/bpf/bpftool/iter.c b/tools/bpf/bpftool/iter.c
new file mode 100644
index 000000000000..db9fae6be716
--- /dev/null
+++ b/tools/bpf/bpftool/iter.c
@@ -0,0 +1,84 @@
+// 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_OR_NULL(obj)) {
+ p_err("can't open objfile %s", objfile);
+ return -1;
+ }
+
+ err = bpf_object__load(obj);
+ if (err < 0) {
+ err = -1;
+ p_err("can't load objfile %s", objfile);
+ goto close_obj;
+ }
+
+ prog = bpf_program__next(NULL, obj);
+ link = bpf_program__attach_iter(prog, NULL);
+ if (IS_ERR(link)) {
+ err = -1;
+ p_err("attach_iter failed for program %s",
+ bpf_program__name(prog));
+ goto close_obj;
+ }
+
+ err = bpf_link__pin(link, path);
+ if (err) {
+ err = -1;
+ p_err("pin_iter failed for program %s to path %s",
+ bpf_program__name(prog), path);
+ goto close_link;
+ }
+
+ err = 0;
+
+close_link:
+ bpf_link__disconnect(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);
+}
diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
index 466c269eabdd..6805b77789cb 100644
--- a/tools/bpf/bpftool/main.c
+++ b/tools/bpf/bpftool/main.c
@@ -58,7 +58,7 @@ static int do_help(int argc, char **argv)
" %s batch file FILE\n"
" %s version\n"
"\n"
- " OBJECT := { prog | map | cgroup | perf | net | feature | btf | gen | struct_ops }\n"
+ " OBJECT := { prog | map | cgroup | perf | net | feature | btf | gen | struct_ops | iter }\n"
" " HELP_SPEC_OPTIONS "\n"
"",
bin_name, bin_name, bin_name);
@@ -222,6 +222,7 @@ static const struct cmd cmds[] = {
{ "btf", do_btf },
{ "gen", do_gen },
{ "struct_ops", do_struct_ops },
+ { "iter", do_iter },
{ "version", do_version },
{ 0 }
};
diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index 86f14ce26fd7..2b5d4a616b48 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -162,6 +162,7 @@ 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);
--
2.24.1