[PATCH v3 net-next 4/4] bpftool: implement cgroup bpf operations

[Roman Gushchin]

This patch adds basic cgroup bpf operations to bpftool:
cgroup list, attach and detach commands.

Usage is described in the corresponding man pages,
and examples are provided.

Syntax:
$ bpftool cgroup list CGROUP
$ bpftool cgroup attach CGROUP ATTACH_TYPE PROG [ATTACH_FLAGS]
$ bpftool cgroup detach CGROUP ATTACH_TYPE PROG

Signed-off-by: Roman Gushchin <guro@xxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: Jakub Kicinski <jakub.kicinski@xxxxxxxxxxxxx>
Cc: Martin KaFai Lau <kafai@xxxxxx>
Cc: Quentin Monnet <quentin.monnet@xxxxxxxxxxxxx>
Reviewed-by: David Ahern <dsahern@xxxxxxxxx>
---
 tools/bpf/bpftool/Documentation/bpftool-cgroup.rst |  92 +++++++
 tools/bpf/bpftool/Documentation/bpftool-map.rst    |   2 +-
 tools/bpf/bpftool/Documentation/bpftool-prog.rst   |   2 +-
 tools/bpf/bpftool/Documentation/bpftool.rst        |   6 +-
 tools/bpf/bpftool/cgroup.c                         | 300 +++++++++++++++++++++
 tools/bpf/bpftool/main.c                           |   3 +-
 tools/bpf/bpftool/main.h                           |   1 +
 7 files changed, 401 insertions(+), 5 deletions(-)
 create mode 100644 tools/bpf/bpftool/Documentation/bpftool-cgroup.rst
 create mode 100644 tools/bpf/bpftool/cgroup.c

diff --git a/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst b/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst
new file mode 100644
index 000000000000..61ded613aee1
--- /dev/null
+++ b/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst
@@ -0,0 +1,92 @@
+================
+bpftool-cgroup
+================
+-------------------------------------------------------------------------------
+tool for inspection and simple manipulation of eBPF progs
+-------------------------------------------------------------------------------
+
+:Manual section: 8
+
+SYNOPSIS
+========
+
+	**bpftool** [*OPTIONS*] **cgroup** *COMMAND*
+
+	*OPTIONS* := { { **-j** | **--json** } [{ **-p** | **--pretty** }] | { **-f** | **--bpffs** } }
+
+	*COMMANDS* :=
+	{ **list** | **attach** | **detach** | **help** }
+
+MAP COMMANDS
+=============
+
+|	**bpftool** **cgroup list** *CGROUP*
+|	**bpftool** **cgroup attach** *CGROUP* *ATTACH_TYPE* *PROG* [*ATTACH_FLAGS*]
+|	**bpftool** **cgroup detach** *CGROUP* *ATTACH_TYPE* *PROG*
+|	**bpftool** **cgroup help**
+|
+|	*PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* }
+
+DESCRIPTION
+===========
+	**bpftool cgroup list** *CGROUP*
+		  List all programs attached to the cgroup *CGROUP*.
+
+		  Output will start with program ID followed by attach type,
+		  attach flags and program name.
+
+	**bpftool cgroup attach** *CGROUP* *ATTACH_TYPE* *PROG* [*ATTACH_FLAGS*]
+		  Attach program *PROG* to the cgroup *CGROUP* with attach type
+		  *ATTACH_TYPE* and optional *ATTACH_FLAGS*.
+
+	**bpftool cgroup detach** *CGROUP* *ATTACH_TYPE* *PROG*
+		  Detach *PROG* from the cgroup *CGROUP* and attach type
+		  *ATTACH_TYPE*.
+
+	**bpftool prog 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**).
+
+	-j, --json
+		  Generate JSON output. For commands that cannot produce JSON, this
+		  option has no effect.
+
+	-p, --pretty
+		  Generate human-readable JSON output. Implies **-j**.
+
+	-f, --bpffs
+		  Show file names of pinned programs.
+
+EXAMPLES
+========
+|
+| **# mount -t bpf none /sys/fs/bpf/**
+| **# mkdir /sys/fs/cgroup/test.slice**
+| **# bpftool prog load ./device_cgroup.o /sys/fs/bpf/prog**
+| **# bpftool cgroup attach /sys/fs/cgroup/test.slice/ device id 1 allow_multi**
+
+**# bpftool cgroup list /sys/fs/cgroup/test.slice/**
+
+::
+
+    ID       AttachType      AttachFlags     Name
+    1        device          allow_multi     bpf_prog1
+
+|
+| **# bpftool cgroup detach /sys/fs/cgroup/test.slice/ device id 1**
+| **# bpftool cgroup list /sys/fs/cgroup/test.slice/**
+
+::
+
+    ID       AttachType      AttachFlags     Name
+
+SEE ALSO
+========
+	**bpftool**\ (8), **bpftool-prog**\ (8), **bpftool-map**\ (8)
diff --git a/tools/bpf/bpftool/Documentation/bpftool-map.rst b/tools/bpf/bpftool/Documentation/bpftool-map.rst
index 9f51a268eb06..421cabc417e6 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-map.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-map.rst
@@ -128,4 +128,4 @@ EXAMPLES
 
 SEE ALSO
 ========
-	**bpftool**\ (8), **bpftool-prog**\ (8)
+	**bpftool**\ (8), **bpftool-prog**\ (8), **bpftool-cgroup**\ (8)
diff --git a/tools/bpf/bpftool/Documentation/bpftool-prog.rst b/tools/bpf/bpftool/Documentation/bpftool-prog.rst
index ffdb20e8280f..81c97c0e9b67 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-prog.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-prog.rst
@@ -155,4 +155,4 @@ EXAMPLES
 
 SEE ALSO
 ========
-	**bpftool**\ (8), **bpftool-map**\ (8)
+	**bpftool**\ (8), **bpftool-map**\ (8), **bpftool-cgroup**\ (8)
diff --git a/tools/bpf/bpftool/Documentation/bpftool.rst b/tools/bpf/bpftool/Documentation/bpftool.rst
index f547a0c0aa34..6732a5a617e4 100644
--- a/tools/bpf/bpftool/Documentation/bpftool.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool.rst
@@ -16,7 +16,7 @@ SYNOPSIS
 
 	**bpftool** **version**
 
-	*OBJECT* := { **map** | **program** }
+	*OBJECT* := { **map** | **program** | **cgroup** }
 
 	*OPTIONS* := { { **-V** | **--version** } | { **-h** | **--help** }
 	| { **-j** | **--json** } [{ **-p** | **--pretty** }] }
@@ -28,6 +28,8 @@ SYNOPSIS
 	*PROG-COMMANDS* := { **show** | **dump jited** | **dump xlated** | **pin**
 	| **load** | **help** }
 
+	*CGROUP-COMMANDS* := { **list** | **attach** | **detach** | **help** }
+
 DESCRIPTION
 ===========
 	*bpftool* allows for inspection and simple modification of BPF objects
@@ -53,4 +55,4 @@ OPTIONS
 
 SEE ALSO
 ========
-	**bpftool-map**\ (8), **bpftool-prog**\ (8)
+	**bpftool-map**\ (8), **bpftool-prog**\ (8), **bpftool-cgroup**\ (8)
diff --git a/tools/bpf/bpftool/cgroup.c b/tools/bpf/bpftool/cgroup.c
new file mode 100644
index 000000000000..8116d58699af
--- /dev/null
+++ b/tools/bpf/bpftool/cgroup.c
@@ -0,0 +1,300 @@
+// SPDX-License-Identifier: GPL-2.0+
+// Copyright (C) 2017 Facebook
+// Author: Roman Gushchin <guro@xxxxxx>
+
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <bpf.h>
+
+#include "main.h"
+
+static const char * const attach_type_strings[] = {
+	[BPF_CGROUP_INET_INGRESS] = "ingress",
+	[BPF_CGROUP_INET_EGRESS] = "egress",
+	[BPF_CGROUP_INET_SOCK_CREATE] = "sock_create",
+	[BPF_CGROUP_SOCK_OPS] = "sock_ops",
+	[BPF_CGROUP_DEVICE] = "device",
+	[__MAX_BPF_ATTACH_TYPE] = NULL,
+};
+
+static enum bpf_attach_type parse_attach_type(const char *str)
+{
+	enum bpf_attach_type type;
+
+	for (type = 0; type < __MAX_BPF_ATTACH_TYPE; type++) {
+		if (attach_type_strings[type] &&
+		    is_prefix(str, attach_type_strings[type]))
+			return type;
+	}
+
+	return __MAX_BPF_ATTACH_TYPE;
+}
+
+static int list_bpf_prog(int id, const char *attach_type_str,
+			 const char *attach_flags_str)
+{
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
+	int prog_fd;
+
+	prog_fd = bpf_prog_get_fd_by_id(id);
+	if (prog_fd < 0)
+		return -1;
+
+	if (bpf_obj_get_info_by_fd(prog_fd, &info, &info_len)) {
+		close(prog_fd);
+		return -1;
+	}
+
+	if (json_output) {
+		jsonw_start_object(json_wtr);
+		jsonw_uint_field(json_wtr, "id", info.id);
+		jsonw_string_field(json_wtr, "attach_type",
+				   attach_type_str);
+		jsonw_string_field(json_wtr, "attach_flags",
+				   attach_flags_str);
+		jsonw_string_field(json_wtr, "name", info.name);
+		jsonw_end_object(json_wtr);
+	} else {
+		printf("%-8u %-15s %-15s %-15s\n", info.id,
+		       attach_type_str,
+		       attach_flags_str,
+		       info.name);
+	}
+
+	close(prog_fd);
+	return 0;
+}
+
+static int list_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type)
+{
+	__u32 prog_ids[1024] = {0};
+	char *attach_flags_str;
+	__u32 prog_cnt, iter;
+	__u32 attach_flags;
+	char buf[16];
+	int ret;
+
+	prog_cnt = ARRAY_SIZE(prog_ids);
+	ret = bpf_prog_query(cgroup_fd, type, 0, &attach_flags, prog_ids,
+			     &prog_cnt);
+	if (ret)
+		return ret;
+
+	if (prog_cnt == 0)
+		return 0;
+
+	switch (attach_flags) {
+	case BPF_F_ALLOW_MULTI:
+		attach_flags_str = "allow_multi";
+		break;
+	case BPF_F_ALLOW_OVERRIDE:
+		attach_flags_str = "allow_override";
+		break;
+	case 0:
+		attach_flags_str = "";
+		break;
+	default:
+		snprintf(buf, sizeof(buf), "unknown(%x)", attach_flags);
+		attach_flags_str = buf;
+	}
+
+	for (iter = 0; iter < prog_cnt; iter++)
+		list_bpf_prog(prog_ids[iter], attach_type_strings[type],
+			      attach_flags_str);
+
+	return 0;
+}
+
+static int do_list(int argc, char **argv)
+{
+	enum bpf_attach_type type;
+	int cgroup_fd;
+	int ret = -1;
+
+	if (argc < 1) {
+		p_err("too few parameters for cgroup list\n");
+		goto exit;
+	} else if (argc > 1) {
+		p_err("too many parameters for cgroup list\n");
+		goto exit;
+	}
+
+	cgroup_fd = open(argv[0], O_RDONLY);
+	if (cgroup_fd < 0) {
+		p_err("can't open cgroup %s\n", argv[1]);
+		goto exit;
+	}
+
+	if (json_output)
+		jsonw_start_array(json_wtr);
+	else
+		printf("%-8s %-15s %-15s %-15s\n", "ID", "AttachType",
+		       "AttachFlags", "Name");
+
+	for (type = 0; type < __MAX_BPF_ATTACH_TYPE; type++) {
+		/*
+		 * Not all attach types may be supported, so it's expected,
+		 * that some requests will fail.
+		 * If we were able to get the list for at least one
+		 * attach type, let's return 0.
+		 */
+		if (list_attached_bpf_progs(cgroup_fd, type) == 0)
+			ret = 0;
+	}
+
+	if (json_output)
+		jsonw_end_array(json_wtr);
+
+	close(cgroup_fd);
+exit:
+	return ret;
+}
+
+static int do_attach(int argc, char **argv)
+{
+	int cgroup_fd, prog_fd;
+	enum bpf_attach_type attach_type;
+	int attach_flags = 0;
+	int i;
+	int ret = -1;
+
+	if (argc < 4) {
+		p_err("too few parameters for cgroup attach\n");
+		goto exit;
+	}
+
+	cgroup_fd = open(argv[0], O_RDONLY);
+	if (cgroup_fd < 0) {
+		p_err("can't open cgroup %s\n", argv[1]);
+		goto exit;
+	}
+
+	attach_type = parse_attach_type(argv[1]);
+	if (attach_type == __MAX_BPF_ATTACH_TYPE) {
+		p_err("invalid attach type\n");
+		goto exit_cgroup;
+	}
+
+	argc -= 2;
+	argv = &argv[2];
+	prog_fd = prog_parse_fd(&argc, &argv);
+	if (prog_fd < 0)
+		goto exit_cgroup;
+
+	for (i = 0; i < argc; i++) {
+		if (strcmp(argv[i], "allow_multi") == 0) {
+			attach_flags |= BPF_F_ALLOW_MULTI;
+		} else if (strcmp(argv[i], "allow_override") == 0) {
+			attach_flags |= BPF_F_ALLOW_OVERRIDE;
+		} else {
+			p_err("unknown option: %s\n", argv[i]);
+			goto exit_cgroup;
+		}
+	}
+
+	if (bpf_prog_attach(prog_fd, cgroup_fd, attach_type, attach_flags)) {
+		p_err("failed to attach program");
+		goto exit_prog;
+	}
+
+	if (json_output)
+		jsonw_null(json_wtr);
+
+	ret = 0;
+
+exit_prog:
+	close(prog_fd);
+exit_cgroup:
+	close(cgroup_fd);
+exit:
+	return ret;
+}
+
+static int do_detach(int argc, char **argv)
+{
+	int prog_fd, cgroup_fd;
+	enum bpf_attach_type attach_type;
+	int ret = -1;
+
+	if (argc < 4) {
+		p_err("too few parameters for cgroup detach\n");
+		goto exit;
+	}
+
+	cgroup_fd = open(argv[0], O_RDONLY);
+	if (cgroup_fd < 0) {
+		p_err("can't open cgroup %s\n", argv[1]);
+		goto exit;
+	}
+
+	attach_type = parse_attach_type(argv[1]);
+	if (attach_type == __MAX_BPF_ATTACH_TYPE) {
+		p_err("invalid attach type");
+		goto exit_cgroup;
+	}
+
+	argc -= 2;
+	argv = &argv[2];
+	prog_fd = prog_parse_fd(&argc, &argv);
+	if (prog_fd < 0)
+		goto exit_cgroup;
+
+	if (bpf_prog_detach2(prog_fd, cgroup_fd, attach_type)) {
+		p_err("failed to detach program");
+		goto exit_prog;
+	}
+
+	if (json_output)
+		jsonw_null(json_wtr);
+
+	ret = 0;
+
+exit_prog:
+	close(prog_fd);
+exit_cgroup:
+	close(cgroup_fd);
+exit:
+	return ret;
+}
+
+static int do_help(int argc, char **argv)
+{
+	if (json_output) {
+		jsonw_null(json_wtr);
+		return 0;
+	}
+
+	fprintf(stderr,
+		"Usage: %s %s list CGROUP\n"
+		"       %s %s attach CGROUP TYPE PROG [ATTACH_FLAGS]\n"
+		"       %s %s detach CGROUP TYPE PROG\n"
+		"       %s %s help\n"
+		"\n"
+		"       ATTACH_FLAGS := { allow_multi | allow_override }"
+		"       " HELP_SPEC_PROGRAM "\n"
+		"       " HELP_SPEC_OPTIONS "\n"
+		"",
+		bin_name, argv[-2], bin_name, argv[-2],
+		bin_name, argv[-2], bin_name, argv[-2]);
+
+	return 0;
+}
+
+static const struct cmd cmds[] = {
+	{ "list",	do_list },
+	{ "attach",	do_attach },
+	{ "detach",	do_detach },
+	{ "help",	do_help },
+	{ 0 }
+};
+
+int do_cgroup(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 d294bc8168be..ecd53ccf1239 100644
--- a/tools/bpf/bpftool/main.c
+++ b/tools/bpf/bpftool/main.c
@@ -85,7 +85,7 @@ static int do_help(int argc, char **argv)
 		"       %s batch file FILE\n"
 		"       %s version\n"
 		"\n"
-		"       OBJECT := { prog | map }\n"
+		"       OBJECT := { prog | map | cgroup }\n"
 		"       " HELP_SPEC_OPTIONS "\n"
 		"",
 		bin_name, bin_name, bin_name);
@@ -173,6 +173,7 @@ static const struct cmd cmds[] = {
 	{ "batch",	do_batch },
 	{ "prog",	do_prog },
 	{ "map",	do_map },
+	{ "cgroup",	do_cgroup },
 	{ "version",	do_version },
 	{ 0 }
 };
diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index bec1ccbb49c7..8f6d3cac0347 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -115,6 +115,7 @@ int do_pin_fd(int fd, const char *name);
 
 int do_prog(int argc, char **arg);
 int do_map(int argc, char **arg);
+int do_cgroup(int argc, char **arg);
 
 int prog_parse_fd(int *argc, char ***argv);
 
-- 
2.14.3