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Commit 2058b383 authored by Roman Gushchin's avatar Roman Gushchin Committed by Daniel Borkmann
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bpftool: introduce cgroup tree command 



This commit introduces a new bpftool command: cgroup tree.
The idea is to iterate over the whole cgroup tree and print
all attached programs.

I was debugging a bpf/systemd issue, and found, that there is
no simple way to listen all bpf programs attached to cgroups.
I did master something in bash, but after some time got tired of it,
and decided, that adding a dedicated bpftool command could be
a better idea.

So, here it is:
  $ sudo ./bpftool cgroup tree
  CgroupPath
  ID       AttachType      AttachFlags     Name
  /sys/fs/cgroup/system.slice/systemd-machined.service
      18       ingress
      17       egress
  /sys/fs/cgroup/system.slice/systemd-logind.service
      20       ingress
      19       egress
  /sys/fs/cgroup/system.slice/systemd-udevd.service
      16       ingress
      15       egress
  /sys/fs/cgroup/system.slice/systemd-journald.service
      14       ingress
      13       egress

Signed-off-by: default avatarRoman Gushchin <guro@fb.com>
Acked-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
Cc: Quentin Monnet <quentin.monnet@netronome.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent ab8565af

tools/bpf/bpftool/cgroup.c

+165 −5
Original line number Diff line number Diff line
@@ -2,7 +2,12 @@ 
// Copyright (C) 2017 Facebook

// Author: Roman Gushchin <guro@fb.com>



#define _XOPEN_SOURCE 500

#include <errno.h>

#include <fcntl.h>

#include <ftw.h>

#include <mntent.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <sys/stat.h>
@@ -53,7 +58,8 @@ static enum bpf_attach_type parse_attach_type(const char *str) 
}



static int show_bpf_prog(int id, const char *attach_type_str,

			 const char *attach_flags_str)

			 const char *attach_flags_str,

			 int level)

{

	struct bpf_prog_info info = {};

	__u32 info_len = sizeof(info);
@@ -78,7 +84,8 @@ static int show_bpf_prog(int id, const char *attach_type_str, 
		jsonw_string_field(json_wtr, "name", info.name);

		jsonw_end_object(json_wtr);

	} else {

		printf("%-8u %-15s %-15s %-15s\n", info.id,

		printf("%s%-8u %-15s %-15s %-15s\n", level ? "    " : "",

		       info.id,

		       attach_type_str,

		       attach_flags_str,

		       info.name);
@@ -88,7 +95,20 @@ static int show_bpf_prog(int id, const char *attach_type_str, 
	return 0;

}



static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type)

static int count_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type)

{

	__u32 prog_cnt = 0;

	int ret;



	ret = bpf_prog_query(cgroup_fd, type, 0, NULL, NULL, &prog_cnt);

	if (ret)

		return -1;



	return prog_cnt;

}



static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type,

				   int level)

{

	__u32 prog_ids[1024] = {0};

	char *attach_flags_str;
@@ -123,7 +143,7 @@ static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type) 


	for (iter = 0; iter < prog_cnt; iter++)

		show_bpf_prog(prog_ids[iter], attach_type_strings[type],

			      attach_flags_str);

			      attach_flags_str, level);



	return 0;

}
@@ -161,7 +181,7 @@ static int do_show(int argc, char **argv) 
		 * If we were able to get the show for at least one

		 * attach type, let's return 0.

		 */

		if (show_attached_bpf_progs(cgroup_fd, type) == 0)

		if (show_attached_bpf_progs(cgroup_fd, type, 0) == 0)

			ret = 0;

	}
@@ -173,6 +193,143 @@ static int do_show(int argc, char **argv) 
	return ret;

}



/*

 * To distinguish nftw() errors and do_show_tree_fn() errors

 * and avoid duplicating error messages, let's return -2

 * from do_show_tree_fn() in case of error.

 */

#define NFTW_ERR		-1

#define SHOW_TREE_FN_ERR	-2

static int do_show_tree_fn(const char *fpath, const struct stat *sb,

			   int typeflag, struct FTW *ftw)

{

	enum bpf_attach_type type;

	bool skip = true;

	int cgroup_fd;



	if (typeflag != FTW_D)

		return 0;



	cgroup_fd = open(fpath, O_RDONLY);

	if (cgroup_fd < 0) {

		p_err("can't open cgroup %s: %s", fpath, strerror(errno));

		return SHOW_TREE_FN_ERR;

	}



	for (type = 0; type < __MAX_BPF_ATTACH_TYPE; type++) {

		int count = count_attached_bpf_progs(cgroup_fd, type);



		if (count < 0 && errno != EINVAL) {

			p_err("can't query bpf programs attached to %s: %s",

			      fpath, strerror(errno));

			close(cgroup_fd);

			return SHOW_TREE_FN_ERR;

		}

		if (count > 0) {

			skip = false;

			break;

		}

	}



	if (skip) {

		close(cgroup_fd);

		return 0;

	}



	if (json_output) {

		jsonw_start_object(json_wtr);

		jsonw_string_field(json_wtr, "cgroup", fpath);

		jsonw_name(json_wtr, "programs");

		jsonw_start_array(json_wtr);

	} else {

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

	}



	for (type = 0; type < __MAX_BPF_ATTACH_TYPE; type++)

		show_attached_bpf_progs(cgroup_fd, type, ftw->level);



	if (json_output) {

		jsonw_end_array(json_wtr);

		jsonw_end_object(json_wtr);

	}



	close(cgroup_fd);



	return 0;

}



static char *find_cgroup_root(void)

{

	struct mntent *mnt;

	FILE *f;



	f = fopen("/proc/mounts", "r");

	if (f == NULL)

		return NULL;



	while ((mnt = getmntent(f))) {

		if (strcmp(mnt->mnt_type, "cgroup2") == 0) {

			fclose(f);

			return strdup(mnt->mnt_dir);

		}

	}



	fclose(f);

	return NULL;

}



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

{

	char *cgroup_root;

	int ret;



	switch (argc) {

	case 0:

		cgroup_root = find_cgroup_root();

		if (!cgroup_root) {

			p_err("cgroup v2 isn't mounted");

			return -1;

		}

		break;

	case 1:

		cgroup_root = argv[0];

		break;

	default:

		p_err("too many parameters for cgroup tree");

		return -1;

	}





	if (json_output)

		jsonw_start_array(json_wtr);

	else

		printf("%s\n"

		       "%-8s %-15s %-15s %-15s\n",

		       "CgroupPath",

		       "ID", "AttachType", "AttachFlags", "Name");



	switch (nftw(cgroup_root, do_show_tree_fn, 1024, FTW_MOUNT)) {

	case NFTW_ERR:

		p_err("can't iterate over %s: %s", cgroup_root,

		      strerror(errno));

		ret = -1;

		break;

	case SHOW_TREE_FN_ERR:

		ret = -1;

		break;

	default:

		ret = 0;

	}



	if (json_output)

		jsonw_end_array(json_wtr);



	if (argc == 0)

		free(cgroup_root);



	return ret;

}



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

{

	enum bpf_attach_type attach_type;
@@ -289,6 +446,7 @@ static int do_help(int argc, char **argv) 


	fprintf(stderr,

		"Usage: %s %s { show | list } CGROUP\n"

		"       %s %s tree [CGROUP_ROOT]\n"

		"       %s %s attach CGROUP ATTACH_TYPE PROG [ATTACH_FLAGS]\n"

		"       %s %s detach CGROUP ATTACH_TYPE PROG\n"

		"       %s %s help\n"
@@ -298,6 +456,7 @@ static int do_help(int argc, char **argv) 
		"       " HELP_SPEC_PROGRAM "\n"

		"       " HELP_SPEC_OPTIONS "\n"

		"",

		bin_name, argv[-2],

		bin_name, argv[-2], bin_name, argv[-2],

		bin_name, argv[-2], bin_name, argv[-2]);
@@ -307,6 +466,7 @@ static int do_help(int argc, char **argv) 
static const struct cmd cmds[] = {

	{ "show",	do_show },

	{ "list",	do_show },

	{ "tree",       do_show_tree },

	{ "attach",	do_attach },

	{ "detach",	do_detach },

	{ "help",	do_help },