linux/tools/bpf/bpftool/cgroup.c
Roman Gushchin 2058b38371 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: Roman Gushchin <guro@fb.com>
Acked-by: Jakub 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: Daniel Borkmann <daniel@iogearbox.net>
2018-07-07 01:38:38 +02:00

480 lines
9.8 KiB
C

// SPDX-License-Identifier: GPL-2.0+
// 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>
#include <sys/types.h>
#include <unistd.h>
#include <bpf.h>
#include "main.h"
#define HELP_SPEC_ATTACH_FLAGS \
"ATTACH_FLAGS := { multi | override }"
#define HELP_SPEC_ATTACH_TYPES \
" ATTACH_TYPE := { ingress | egress | sock_create |\n" \
" sock_ops | device | bind4 | bind6 |\n" \
" post_bind4 | post_bind6 | connect4 |\n" \
" connect6 | sendmsg4 | sendmsg6 }"
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",
[BPF_CGROUP_INET4_BIND] = "bind4",
[BPF_CGROUP_INET6_BIND] = "bind6",
[BPF_CGROUP_INET4_CONNECT] = "connect4",
[BPF_CGROUP_INET6_CONNECT] = "connect6",
[BPF_CGROUP_INET4_POST_BIND] = "post_bind4",
[BPF_CGROUP_INET6_POST_BIND] = "post_bind6",
[BPF_CGROUP_UDP4_SENDMSG] = "sendmsg4",
[BPF_CGROUP_UDP6_SENDMSG] = "sendmsg6",
[__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 show_bpf_prog(int id, const char *attach_type_str,
const char *attach_flags_str,
int level)
{
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("%s%-8u %-15s %-15s %-15s\n", level ? " " : "",
info.id,
attach_type_str,
attach_flags_str,
info.name);
}
close(prog_fd);
return 0;
}
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;
__u32 prog_cnt, iter;
__u32 attach_flags;
char buf[32];
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 = "multi";
break;
case BPF_F_ALLOW_OVERRIDE:
attach_flags_str = "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++)
show_bpf_prog(prog_ids[iter], attach_type_strings[type],
attach_flags_str, level);
return 0;
}
static int do_show(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 show");
goto exit;
} else if (argc > 1) {
p_err("too many parameters for cgroup show");
goto exit;
}
cgroup_fd = open(argv[0], O_RDONLY);
if (cgroup_fd < 0) {
p_err("can't open cgroup %s", 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 show for at least one
* attach type, let's return 0.
*/
if (show_attached_bpf_progs(cgroup_fd, type, 0) == 0)
ret = 0;
}
if (json_output)
jsonw_end_array(json_wtr);
close(cgroup_fd);
exit:
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;
int cgroup_fd, prog_fd;
int attach_flags = 0;
int ret = -1;
int i;
if (argc < 4) {
p_err("too few parameters for cgroup attach");
goto exit;
}
cgroup_fd = open(argv[0], O_RDONLY);
if (cgroup_fd < 0) {
p_err("can't open cgroup %s", 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;
for (i = 0; i < argc; i++) {
if (is_prefix(argv[i], "multi")) {
attach_flags |= BPF_F_ALLOW_MULTI;
} else if (is_prefix(argv[i], "override")) {
attach_flags |= BPF_F_ALLOW_OVERRIDE;
} else {
p_err("unknown option: %s", 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)
{
enum bpf_attach_type attach_type;
int prog_fd, cgroup_fd;
int ret = -1;
if (argc < 4) {
p_err("too few parameters for cgroup detach");
goto exit;
}
cgroup_fd = open(argv[0], O_RDONLY);
if (cgroup_fd < 0) {
p_err("can't open cgroup %s", 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 { 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"
"\n"
HELP_SPEC_ATTACH_TYPES "\n"
" " HELP_SPEC_ATTACH_FLAGS "\n"
" " 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]);
return 0;
}
static const struct cmd cmds[] = {
{ "show", do_show },
{ "list", do_show },
{ "tree", do_show_tree },
{ "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);
}