linux/tools/bpf/bpftool/link.c
Kui-Feng Lee 6bdb6d6be0 bpftool: Show parameters of BPF task iterators.
Show tid or pid of iterators if giving an argument of tid or pid

For example, the command `bpftool link list` may list following
lines.

1: iter  prog 2  target_name bpf_map
2: iter  prog 3  target_name bpf_prog
33: iter  prog 225  target_name task_file  tid 1644
        pids test_progs(1644)

Link 33 is a task_file iterator with tid 1644.  For now, only targets
of task, task_file and task_vma may be with tid or pid to filter out
tasks other than those belonging to a process (pid) or a thread (tid).

Signed-off-by: Kui-Feng Lee <kuifeng@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/bpf/20220926184957.208194-6-kuifeng@fb.com
2022-09-28 16:30:08 -07:00

496 lines
11 KiB
C

// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
/* Copyright (C) 2020 Facebook */
#include <errno.h>
#include <linux/err.h>
#include <net/if.h>
#include <stdio.h>
#include <unistd.h>
#include <bpf/bpf.h>
#include <bpf/hashmap.h>
#include "json_writer.h"
#include "main.h"
static struct hashmap *link_table;
static int link_parse_fd(int *argc, char ***argv)
{
int fd;
if (is_prefix(**argv, "id")) {
unsigned int id;
char *endptr;
NEXT_ARGP();
id = strtoul(**argv, &endptr, 0);
if (*endptr) {
p_err("can't parse %s as ID", **argv);
return -1;
}
NEXT_ARGP();
fd = bpf_link_get_fd_by_id(id);
if (fd < 0)
p_err("failed to get link with ID %d: %s", id, strerror(errno));
return fd;
} else if (is_prefix(**argv, "pinned")) {
char *path;
NEXT_ARGP();
path = **argv;
NEXT_ARGP();
return open_obj_pinned_any(path, BPF_OBJ_LINK);
}
p_err("expected 'id' or 'pinned', got: '%s'?", **argv);
return -1;
}
static void
show_link_header_json(struct bpf_link_info *info, json_writer_t *wtr)
{
const char *link_type_str;
jsonw_uint_field(wtr, "id", info->id);
link_type_str = libbpf_bpf_link_type_str(info->type);
if (link_type_str)
jsonw_string_field(wtr, "type", link_type_str);
else
jsonw_uint_field(wtr, "type", info->type);
jsonw_uint_field(json_wtr, "prog_id", info->prog_id);
}
static void show_link_attach_type_json(__u32 attach_type, json_writer_t *wtr)
{
const char *attach_type_str;
attach_type_str = libbpf_bpf_attach_type_str(attach_type);
if (attach_type_str)
jsonw_string_field(wtr, "attach_type", attach_type_str);
else
jsonw_uint_field(wtr, "attach_type", attach_type);
}
static bool is_iter_map_target(const char *target_name)
{
return strcmp(target_name, "bpf_map_elem") == 0 ||
strcmp(target_name, "bpf_sk_storage_map") == 0;
}
static bool is_iter_cgroup_target(const char *target_name)
{
return strcmp(target_name, "cgroup") == 0;
}
static const char *cgroup_order_string(__u32 order)
{
switch (order) {
case BPF_CGROUP_ITER_ORDER_UNSPEC:
return "order_unspec";
case BPF_CGROUP_ITER_SELF_ONLY:
return "self_only";
case BPF_CGROUP_ITER_DESCENDANTS_PRE:
return "descendants_pre";
case BPF_CGROUP_ITER_DESCENDANTS_POST:
return "descendants_post";
case BPF_CGROUP_ITER_ANCESTORS_UP:
return "ancestors_up";
default: /* won't happen */
return "unknown";
}
}
static bool is_iter_task_target(const char *target_name)
{
return strcmp(target_name, "task") == 0 ||
strcmp(target_name, "task_file") == 0 ||
strcmp(target_name, "task_vma") == 0;
}
static void show_iter_json(struct bpf_link_info *info, json_writer_t *wtr)
{
const char *target_name = u64_to_ptr(info->iter.target_name);
jsonw_string_field(wtr, "target_name", target_name);
if (is_iter_map_target(target_name))
jsonw_uint_field(wtr, "map_id", info->iter.map.map_id);
else if (is_iter_task_target(target_name)) {
if (info->iter.task.tid)
jsonw_uint_field(wtr, "tid", info->iter.task.tid);
else if (info->iter.task.pid)
jsonw_uint_field(wtr, "pid", info->iter.task.pid);
}
if (is_iter_cgroup_target(target_name)) {
jsonw_lluint_field(wtr, "cgroup_id", info->iter.cgroup.cgroup_id);
jsonw_string_field(wtr, "order",
cgroup_order_string(info->iter.cgroup.order));
}
}
static int get_prog_info(int prog_id, struct bpf_prog_info *info)
{
__u32 len = sizeof(*info);
int err, prog_fd;
prog_fd = bpf_prog_get_fd_by_id(prog_id);
if (prog_fd < 0)
return prog_fd;
memset(info, 0, sizeof(*info));
err = bpf_obj_get_info_by_fd(prog_fd, info, &len);
if (err)
p_err("can't get prog info: %s", strerror(errno));
close(prog_fd);
return err;
}
static int show_link_close_json(int fd, struct bpf_link_info *info)
{
struct bpf_prog_info prog_info;
const char *prog_type_str;
int err;
jsonw_start_object(json_wtr);
show_link_header_json(info, json_wtr);
switch (info->type) {
case BPF_LINK_TYPE_RAW_TRACEPOINT:
jsonw_string_field(json_wtr, "tp_name",
u64_to_ptr(info->raw_tracepoint.tp_name));
break;
case BPF_LINK_TYPE_TRACING:
err = get_prog_info(info->prog_id, &prog_info);
if (err)
return err;
prog_type_str = libbpf_bpf_prog_type_str(prog_info.type);
/* libbpf will return NULL for variants unknown to it. */
if (prog_type_str)
jsonw_string_field(json_wtr, "prog_type", prog_type_str);
else
jsonw_uint_field(json_wtr, "prog_type", prog_info.type);
show_link_attach_type_json(info->tracing.attach_type,
json_wtr);
break;
case BPF_LINK_TYPE_CGROUP:
jsonw_lluint_field(json_wtr, "cgroup_id",
info->cgroup.cgroup_id);
show_link_attach_type_json(info->cgroup.attach_type, json_wtr);
break;
case BPF_LINK_TYPE_ITER:
show_iter_json(info, json_wtr);
break;
case BPF_LINK_TYPE_NETNS:
jsonw_uint_field(json_wtr, "netns_ino",
info->netns.netns_ino);
show_link_attach_type_json(info->netns.attach_type, json_wtr);
break;
default:
break;
}
if (!hashmap__empty(link_table)) {
struct hashmap_entry *entry;
jsonw_name(json_wtr, "pinned");
jsonw_start_array(json_wtr);
hashmap__for_each_key_entry(link_table, entry,
u32_as_hash_field(info->id))
jsonw_string(json_wtr, entry->value);
jsonw_end_array(json_wtr);
}
emit_obj_refs_json(refs_table, info->id, json_wtr);
jsonw_end_object(json_wtr);
return 0;
}
static void show_link_header_plain(struct bpf_link_info *info)
{
const char *link_type_str;
printf("%u: ", info->id);
link_type_str = libbpf_bpf_link_type_str(info->type);
if (link_type_str)
printf("%s ", link_type_str);
else
printf("type %u ", info->type);
printf("prog %u ", info->prog_id);
}
static void show_link_attach_type_plain(__u32 attach_type)
{
const char *attach_type_str;
attach_type_str = libbpf_bpf_attach_type_str(attach_type);
if (attach_type_str)
printf("attach_type %s ", attach_type_str);
else
printf("attach_type %u ", attach_type);
}
static void show_iter_plain(struct bpf_link_info *info)
{
const char *target_name = u64_to_ptr(info->iter.target_name);
printf("target_name %s ", target_name);
if (is_iter_map_target(target_name))
printf("map_id %u ", info->iter.map.map_id);
else if (is_iter_task_target(target_name)) {
if (info->iter.task.tid)
printf("tid %u ", info->iter.task.tid);
else if (info->iter.task.pid)
printf("pid %u ", info->iter.task.pid);
}
if (is_iter_cgroup_target(target_name)) {
printf("cgroup_id %llu ", info->iter.cgroup.cgroup_id);
printf("order %s ",
cgroup_order_string(info->iter.cgroup.order));
}
}
static int show_link_close_plain(int fd, struct bpf_link_info *info)
{
struct bpf_prog_info prog_info;
const char *prog_type_str;
int err;
show_link_header_plain(info);
switch (info->type) {
case BPF_LINK_TYPE_RAW_TRACEPOINT:
printf("\n\ttp '%s' ",
(const char *)u64_to_ptr(info->raw_tracepoint.tp_name));
break;
case BPF_LINK_TYPE_TRACING:
err = get_prog_info(info->prog_id, &prog_info);
if (err)
return err;
prog_type_str = libbpf_bpf_prog_type_str(prog_info.type);
/* libbpf will return NULL for variants unknown to it. */
if (prog_type_str)
printf("\n\tprog_type %s ", prog_type_str);
else
printf("\n\tprog_type %u ", prog_info.type);
show_link_attach_type_plain(info->tracing.attach_type);
break;
case BPF_LINK_TYPE_CGROUP:
printf("\n\tcgroup_id %zu ", (size_t)info->cgroup.cgroup_id);
show_link_attach_type_plain(info->cgroup.attach_type);
break;
case BPF_LINK_TYPE_ITER:
show_iter_plain(info);
break;
case BPF_LINK_TYPE_NETNS:
printf("\n\tnetns_ino %u ", info->netns.netns_ino);
show_link_attach_type_plain(info->netns.attach_type);
break;
default:
break;
}
if (!hashmap__empty(link_table)) {
struct hashmap_entry *entry;
hashmap__for_each_key_entry(link_table, entry,
u32_as_hash_field(info->id))
printf("\n\tpinned %s", (char *)entry->value);
}
emit_obj_refs_plain(refs_table, info->id, "\n\tpids ");
printf("\n");
return 0;
}
static int do_show_link(int fd)
{
struct bpf_link_info info;
__u32 len = sizeof(info);
char buf[256];
int err;
memset(&info, 0, sizeof(info));
again:
err = bpf_obj_get_info_by_fd(fd, &info, &len);
if (err) {
p_err("can't get link info: %s",
strerror(errno));
close(fd);
return err;
}
if (info.type == BPF_LINK_TYPE_RAW_TRACEPOINT &&
!info.raw_tracepoint.tp_name) {
info.raw_tracepoint.tp_name = (unsigned long)&buf;
info.raw_tracepoint.tp_name_len = sizeof(buf);
goto again;
}
if (info.type == BPF_LINK_TYPE_ITER &&
!info.iter.target_name) {
info.iter.target_name = (unsigned long)&buf;
info.iter.target_name_len = sizeof(buf);
goto again;
}
if (json_output)
show_link_close_json(fd, &info);
else
show_link_close_plain(fd, &info);
close(fd);
return 0;
}
static int do_show(int argc, char **argv)
{
__u32 id = 0;
int err, fd;
if (show_pinned) {
link_table = hashmap__new(hash_fn_for_key_as_id,
equal_fn_for_key_as_id, NULL);
if (IS_ERR(link_table)) {
p_err("failed to create hashmap for pinned paths");
return -1;
}
build_pinned_obj_table(link_table, BPF_OBJ_LINK);
}
build_obj_refs_table(&refs_table, BPF_OBJ_LINK);
if (argc == 2) {
fd = link_parse_fd(&argc, &argv);
if (fd < 0)
return fd;
return do_show_link(fd);
}
if (argc)
return BAD_ARG();
if (json_output)
jsonw_start_array(json_wtr);
while (true) {
err = bpf_link_get_next_id(id, &id);
if (err) {
if (errno == ENOENT)
break;
p_err("can't get next link: %s%s", strerror(errno),
errno == EINVAL ? " -- kernel too old?" : "");
break;
}
fd = bpf_link_get_fd_by_id(id);
if (fd < 0) {
if (errno == ENOENT)
continue;
p_err("can't get link by id (%u): %s",
id, strerror(errno));
break;
}
err = do_show_link(fd);
if (err)
break;
}
if (json_output)
jsonw_end_array(json_wtr);
delete_obj_refs_table(refs_table);
if (show_pinned)
delete_pinned_obj_table(link_table);
return errno == ENOENT ? 0 : -1;
}
static int do_pin(int argc, char **argv)
{
int err;
err = do_pin_any(argc, argv, link_parse_fd);
if (!err && json_output)
jsonw_null(json_wtr);
return err;
}
static int do_detach(int argc, char **argv)
{
int err, fd;
if (argc != 2) {
p_err("link specifier is invalid or missing\n");
return 1;
}
fd = link_parse_fd(&argc, &argv);
if (fd < 0)
return 1;
err = bpf_link_detach(fd);
if (err)
err = -errno;
close(fd);
if (err) {
p_err("failed link detach: %s", strerror(-err));
return 1;
}
if (json_output)
jsonw_null(json_wtr);
return 0;
}
static int do_help(int argc, char **argv)
{
if (json_output) {
jsonw_null(json_wtr);
return 0;
}
fprintf(stderr,
"Usage: %1$s %2$s { show | list } [LINK]\n"
" %1$s %2$s pin LINK FILE\n"
" %1$s %2$s detach LINK\n"
" %1$s %2$s help\n"
"\n"
" " HELP_SPEC_LINK "\n"
" " HELP_SPEC_OPTIONS " |\n"
" {-f|--bpffs} | {-n|--nomount} }\n"
"",
bin_name, argv[-2]);
return 0;
}
static const struct cmd cmds[] = {
{ "show", do_show },
{ "list", do_show },
{ "help", do_help },
{ "pin", do_pin },
{ "detach", do_detach },
{ 0 }
};
int do_link(int argc, char **argv)
{
return cmd_select(cmds, argc, argv, do_help);
}