linux/tools/bpf/bpftool/link.c
Quentin Monnet d6699f8e0f bpftool: Switch to libbpf's hashmap for PIDs/names references
In order to show PIDs and names for processes holding references to BPF
programs, maps, links, or BTF objects, bpftool creates hash maps to
store all relevant information. This commit is part of a set that
transitions from the kernel's hash map implementation to the one coming
with libbpf.

The motivation is to make bpftool less dependent of kernel headers, to
ease the path to a potential out-of-tree mirror, like libbpf has.

This is the third and final step of the transition, in which we convert
the hash maps used for storing the information about the processes
holding references to BPF objects (programs, maps, links, BTF), and at
last we drop the inclusion of tools/include/linux/hashtable.h.

Note: Checkpatch complains about the use of __weak declarations, and the
missing empty lines after the bunch of empty function declarations when
compiling without the BPF skeletons (none of these were introduced in
this patch). We want to keep things as they are, and the reports should
be safe to ignore.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211023205154.6710-6-quentin@isovalent.com
2021-10-25 17:31:39 -07:00

436 lines
9.4 KiB
C

// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
/* Copyright (C) 2020 Facebook */
#include <errno.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 const char * const link_type_name[] = {
[BPF_LINK_TYPE_UNSPEC] = "unspec",
[BPF_LINK_TYPE_RAW_TRACEPOINT] = "raw_tracepoint",
[BPF_LINK_TYPE_TRACING] = "tracing",
[BPF_LINK_TYPE_CGROUP] = "cgroup",
[BPF_LINK_TYPE_ITER] = "iter",
[BPF_LINK_TYPE_NETNS] = "netns",
};
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)
{
jsonw_uint_field(wtr, "id", info->id);
if (info->type < ARRAY_SIZE(link_type_name))
jsonw_string_field(wtr, "type", link_type_name[info->type]);
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)
{
if (attach_type < ARRAY_SIZE(attach_type_name))
jsonw_string_field(wtr, "attach_type",
attach_type_name[attach_type]);
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 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);
}
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;
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;
if (prog_info.type < prog_type_name_size)
jsonw_string_field(json_wtr, "prog_type",
prog_type_name[prog_info.type]);
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)
{
printf("%u: ", info->id);
if (info->type < ARRAY_SIZE(link_type_name))
printf("%s ", link_type_name[info->type]);
else
printf("type %u ", info->type);
printf("prog %u ", info->prog_id);
}
static void show_link_attach_type_plain(__u32 attach_type)
{
if (attach_type < ARRAY_SIZE(attach_type_name))
printf("attach_type %s ", attach_type_name[attach_type]);
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);
}
static int show_link_close_plain(int fd, struct bpf_link_info *info)
{
struct bpf_prog_info prog_info;
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;
if (prog_info.type < prog_type_name_size)
printf("\n\tprog_type %s ",
prog_type_name[prog_info.type]);
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 (!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);
}