// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
/* Copyright (C) 2020 Facebook */
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include <linux/err.h>
#include <bpf/bpf.h>
#include <bpf/btf.h>
#include <bpf/libbpf.h>
#include "json_writer.h"
#include "main.h"
#define STRUCT_OPS_VALUE_PREFIX "bpf_struct_ops_"
static const struct btf_type *map_info_type;
static __u32 map_info_alloc_len;
static struct btf *btf_vmlinux;
static __s32 map_info_type_id;
struct res {
unsigned int nr_maps;
unsigned int nr_errs;
};
static const struct btf *get_btf_vmlinux(void)
{
if (btf_vmlinux)
return btf_vmlinux;
btf_vmlinux = libbpf_find_kernel_btf();
if (!btf_vmlinux)
p_err("struct_ops requires kernel CONFIG_DEBUG_INFO_BTF=y");
return btf_vmlinux;
}
static const char *get_kern_struct_ops_name(const struct bpf_map_info *info)
{
const struct btf *kern_btf;
const struct btf_type *t;
const char *st_ops_name;
kern_btf = get_btf_vmlinux();
if (!kern_btf)
return "<btf_vmlinux_not_found>";
t = btf__type_by_id(kern_btf, info->btf_vmlinux_value_type_id);
st_ops_name = btf__name_by_offset(kern_btf, t->name_off);
st_ops_name += strlen(STRUCT_OPS_VALUE_PREFIX);
return st_ops_name;
}
static __s32 get_map_info_type_id(void)
{
const struct btf *kern_btf;
if (map_info_type_id)
return map_info_type_id;
kern_btf = get_btf_vmlinux();
if (!kern_btf)
return 0;
map_info_type_id = btf__find_by_name_kind(kern_btf, "bpf_map_info",
BTF_KIND_STRUCT);
if (map_info_type_id < 0) {
p_err("can't find bpf_map_info from btf_vmlinux");
return map_info_type_id;
}
map_info_type = btf__type_by_id(kern_btf, map_info_type_id);
/* Ensure map_info_alloc() has at least what the bpftool needs */
map_info_alloc_len = map_info_type->size;
if (map_info_alloc_len < sizeof(struct bpf_map_info))
map_info_alloc_len = sizeof(struct bpf_map_info);
return map_info_type_id;
}
/* If the subcmd needs to print out the bpf_map_info,
* it should always call map_info_alloc to allocate
* a bpf_map_info object instead of allocating it
* on the stack.
*
* map_info_alloc() will take the running kernel's btf
* into account. i.e. it will consider the
* sizeof(struct bpf_map_info) of the running kernel.
*
* It will enable the "struct_ops" cmd to print the latest
* "struct bpf_map_info".
*
* [ Recall that "struct_ops" requires the kernel's btf to
* be available ]
*/
static struct bpf_map_info *map_info_alloc(__u32 *alloc_len)
{
struct bpf_map_info *info;
if (get_map_info_type_id() < 0)
return NULL;
info = calloc(1, map_info_alloc_len);
if (!info)
p_err("mem alloc failed");
else
*alloc_len = map_info_alloc_len;
return info;
}
/* It iterates all struct_ops maps of the system.
* It returns the fd in "*res_fd" and map_info in "*info".
* In the very first iteration, info->id should be 0.
* An optional map "*name" filter can be specified.
* The filter can be made more flexible in the future.
* e.g. filter by kernel-struct-ops-name, regex-name, glob-name, ...etc.
*
* Return value:
* 1: A struct_ops map found. It is returned in "*res_fd" and "*info".
* The caller can continue to call get_next in the future.
* 0: No struct_ops map is returned.
* All struct_ops map has been found.
* -1: Error and the caller should abort the iteration.
*/
static int get_next_struct_ops_map(const char *name, int *res_fd,
struct bpf_map_info *info, __u32 info_len)
{
__u32 id = info->id;
int err, fd;
while (true) {
err = bpf_map_get_next_id(id, &id);
if (err) {
if (errno == ENOENT)
return 0;
p_err("can't get next map: %s", strerror(errno));
return -1;
}
fd = bpf_map_get_fd_by_id(id);
if (fd < 0) {
if (errno == ENOENT)
continue;
p_err("can't get map by id (%u): %s",
id, strerror(errno));
return -1;
}
err = bpf_map_get_info_by_fd(fd, info, &info_len);
if (err) {
p_err("can't get map info: %s", strerror(errno));
close(fd);
return -1;
}
if (info->type == BPF_MAP_TYPE_STRUCT_OPS &&
(!name || !strcmp(name, info->name))) {
*res_fd = fd;
return 1;
}
close(fd);
}
}
static int cmd_retval(const struct res *res, bool must_have_one_map)
{
if (res->nr_errs || (!res->nr_maps && must_have_one_map))
return -1;
return 0;
}
/* "data" is the work_func private storage */
typedef int (*work_func)(int fd, const struct bpf_map_info *info, void *data,
struct json_writer *wtr);
/* Find all struct_ops map in the system.
* Filter out by "name" (if specified).
* Then call "func(fd, info, data, wtr)" on each struct_ops map found.
*/
static struct res do_search(const char *name, work_func func, void *data,
struct json_writer *wtr)
{
struct bpf_map_info *info;
struct res res = {};
__u32 info_len;
int fd, err;
info = map_info_alloc(&info_len);
if (!info) {
res.nr_errs++;
return res;
}
if (wtr)
jsonw_start_array(wtr);
while ((err = get_next_struct_ops_map(name, &fd, info, info_len)) == 1) {
res.nr_maps++;
err = func(fd, info, data, wtr);
if (err)
res.nr_errs++;
close(fd);
}
if (wtr)
jsonw_end_array(wtr);
if (err)
res.nr_errs++;
if (!wtr && name && !res.nr_errs && !res.nr_maps)
/* It is not printing empty [].
* Thus, needs to specifically say nothing found
* for "name" here.
*/
p_err("no struct_ops found for %s", name);
else if (!wtr && json_output && !res.nr_errs)
/* The "func()" above is not writing any json (i.e. !wtr
* test here).
*
* However, "-j" is enabled and there is no errs here,
* so call json_null() as the current convention of
* other cmds.
*/
jsonw_null(json_wtr);
free(info);
return res;
}
static struct res do_one_id(const char *id_str, work_func func, void *data,
struct json_writer *wtr)
{
struct bpf_map_info *info;
struct res res = {};
unsigned long id;
__u32 info_len;
char *endptr;
int fd;
id = strtoul(id_str, &endptr, 0);
if (*endptr || !id || id > UINT32_MAX) {
p_err("invalid id %s", id_str);
res.nr_errs++;
return res;
}
fd = bpf_map_get_fd_by_id(id);
if (fd < 0) {
p_err("can't get map by id (%lu): %s", id, strerror(errno));
res.nr_errs++;
return res;
}
info = map_info_alloc(&info_len);
if (!info) {
res.nr_errs++;
goto done;
}
if (bpf_map_get_info_by_fd(fd, info, &info_len)) {
p_err("can't get map info: %s", strerror(errno));
res.nr_errs++;
goto done;
}
if (info->type != BPF_MAP_TYPE_STRUCT_OPS) {
p_err("%s id %u is not a struct_ops map", info->name, info->id);
res.nr_errs++;
goto done;
}
res.nr_maps++;
if (wtr)
jsonw_start_array(wtr);
if (func(fd, info, data, wtr))
res.nr_errs++;
else if (!wtr && json_output)
/* The "func()" above is not writing any json (i.e. !wtr
* test here).
*
* However, "-j" is enabled and there is no errs here,
* so call json_null() as the current convention of
* other cmds.
*/
jsonw_null(json_wtr);
if (wtr)
jsonw_end_array(wtr);
done:
free(info);
close(fd);
return res;
}
static struct res do_work_on_struct_ops(const char *search_type,
const char *search_term,
work_func func, void *data,
struct json_writer *wtr)
{
if (search_type) {
if (is_prefix(search_type, "id"))
return do_one_id(search_term, func, data, wtr);
else if (!is_prefix(search_type, "name"))
usage();
}
return do_search(search_term, func, data, wtr);
}
static int __do_show(int fd, const struct bpf_map_info *info, void *data,
struct json_writer *wtr)
{
if (wtr) {
jsonw_start_object(wtr);
jsonw_uint_field(wtr, "id", info->id);
jsonw_string_field(wtr, "name", info->name);
jsonw_string_field(wtr, "kernel_struct_ops",
get_kern_struct_ops_name(info));
jsonw_end_object(wtr);
} else {
printf("%u: %-15s %-32s\n", info->id, info->name,
get_kern_struct_ops_name(info));
}
return 0;
}
static int do_show(int argc, char **argv)
{
const char *search_type = NULL, *search_term = NULL;
struct res res;
if (argc && argc != 2)
usage();
if (argc == 2) {
search_type = GET_ARG();
search_term = GET_ARG();
}
res = do_work_on_struct_ops(search_type, search_term, __do_show,
NULL, json_wtr);
return cmd_retval(&res, !!search_term);
}
static int __do_dump(int fd, const struct bpf_map_info *info, void *data,
struct json_writer *wtr)
{
struct btf_dumper *d = (struct btf_dumper *)data;
const struct btf_type *struct_ops_type;
const struct btf *kern_btf = d->btf;
const char *struct_ops_name;
int zero = 0;
void *value;
/* note: d->jw == wtr */
kern_btf = d->btf;
/* The kernel supporting BPF_MAP_TYPE_STRUCT_OPS must have
* btf_vmlinux_value_type_id.
*/
struct_ops_type = btf__type_by_id(kern_btf,
info->btf_vmlinux_value_type_id);
struct_ops_name = btf__name_by_offset(kern_btf,
struct_ops_type->name_off);
value = calloc(1, info->value_size);
if (!value) {
p_err("mem alloc failed");
return -1;
}
if (bpf_map_lookup_elem(fd, &zero, value)) {
p_err("can't lookup struct_ops map %s id %u",
info->name, info->id);
free(value);
return -1;
}
jsonw_start_object(wtr);
jsonw_name(wtr, "bpf_map_info");
btf_dumper_type(d, map_info_type_id, (void *)info);
jsonw_end_object(wtr);
jsonw_start_object(wtr);
jsonw_name(wtr, struct_ops_name);
btf_dumper_type(d, info->btf_vmlinux_value_type_id, value);
jsonw_end_object(wtr);
free(value);
return 0;
}
static int do_dump(int argc, char **argv)
{
const char *search_type = NULL, *search_term = NULL;
json_writer_t *wtr = json_wtr;
const struct btf *kern_btf;
struct btf_dumper d = {};
struct res res;
if (argc && argc != 2)
usage();
if (argc == 2) {
search_type = GET_ARG();
search_term = GET_ARG();
}
kern_btf = get_btf_vmlinux();
if (!kern_btf)
return -1;
if (!json_output) {
wtr = jsonw_new(stdout);
if (!wtr) {
p_err("can't create json writer");
return -1;
}
jsonw_pretty(wtr, true);
}
d.btf = kern_btf;
d.jw = wtr;
d.is_plain_text = !json_output;
d.prog_id_as_func_ptr = true;
res = do_work_on_struct_ops(search_type, search_term, __do_dump, &d,
wtr);
if (!json_output)
jsonw_destroy(&wtr);
return cmd_retval(&res, !!search_term);
}
static int __do_unregister(int fd, const struct bpf_map_info *info, void *data,
struct json_writer *wtr)
{
int zero = 0;
if (bpf_map_delete_elem(fd, &zero)) {
p_err("can't unload %s %s id %u: %s",
get_kern_struct_ops_name(info), info->name,
info->id, strerror(errno));
return -1;
}
p_info("Unregistered %s %s id %u",
get_kern_struct_ops_name(info), info->name,
info->id);
return 0;
}
static int do_unregister(int argc, char **argv)
{
const char *search_type, *search_term;
struct res res;
if (argc != 2)
usage();
search_type = GET_ARG();
search_term = GET_ARG();
res = do_work_on_struct_ops(search_type, search_term,
__do_unregister, NULL, NULL);
return cmd_retval(&res, true);
}
static int pin_link(struct bpf_link *link, const char *pindir,
const char *name)
{
char pinfile[PATH_MAX];
int err;
err = pathname_concat(pinfile, sizeof(pinfile), pindir, name);
if (err)
return -1;
return bpf_link__pin(link, pinfile);
}
static int do_register(int argc, char **argv)
{
LIBBPF_OPTS(bpf_object_open_opts, open_opts);
__u32 link_info_len = sizeof(struct bpf_link_info);
struct bpf_link_info link_info = {};
struct bpf_map_info info = {};
__u32 info_len = sizeof(info);
int nr_errs = 0, nr_maps = 0;
const char *linkdir = NULL;
struct bpf_object *obj;
struct bpf_link *link;
struct bpf_map *map;
const char *file;
if (argc != 1 && argc != 2)
usage();
file = GET_ARG();
if (argc == 1)
linkdir = GET_ARG();
if (linkdir && create_and_mount_bpffs_dir(linkdir)) {
p_err("can't mount bpffs for pinning");
return -1;
}
if (verifier_logs)
/* log_level1 + log_level2 + stats, but not stable UAPI */
open_opts.kernel_log_level = 1 + 2 + 4;
obj = bpf_object__open_file(file, &open_opts);
if (!obj)
return -1;
set_max_rlimit();
if (bpf_object__load(obj)) {
bpf_object__close(obj);
return -1;
}
bpf_object__for_each_map(map, obj) {
if (bpf_map__type(map) != BPF_MAP_TYPE_STRUCT_OPS)
continue;
link = bpf_map__attach_struct_ops(map);
if (!link) {
p_err("can't register struct_ops %s: %s",
bpf_map__name(map), strerror(errno));
nr_errs++;
continue;
}
nr_maps++;
if (bpf_map_get_info_by_fd(bpf_map__fd(map), &info,
&info_len)) {
/* Not p_err. The struct_ops was attached
* successfully.
*/
p_info("Registered %s but can't find id: %s",
bpf_map__name(map), strerror(errno));
goto clean_link;
}
if (!(bpf_map__map_flags(map) & BPF_F_LINK)) {
p_info("Registered %s %s id %u",
get_kern_struct_ops_name(&info),
info.name,
info.id);
goto clean_link;
}
if (bpf_link_get_info_by_fd(bpf_link__fd(link),
&link_info,
&link_info_len)) {
p_err("Registered %s but can't find link id: %s",
bpf_map__name(map), strerror(errno));
nr_errs++;
goto clean_link;
}
if (linkdir && pin_link(link, linkdir, info.name)) {
p_err("can't pin link %u for %s: %s",
link_info.id, info.name,
strerror(errno));
nr_errs++;
goto clean_link;
}
p_info("Registered %s %s map id %u link id %u",
get_kern_struct_ops_name(&info),
info.name, info.id, link_info.id);
clean_link:
bpf_link__disconnect(link);
bpf_link__destroy(link);
}
bpf_object__close(obj);
if (nr_errs)
return -1;
if (!nr_maps) {
p_err("no struct_ops found in %s", file);
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 } [STRUCT_OPS_MAP]\n"
" %1$s %2$s dump [STRUCT_OPS_MAP]\n"
" %1$s %2$s register OBJ [LINK_DIR]\n"
" %1$s %2$s unregister STRUCT_OPS_MAP\n"
" %1$s %2$s help\n"
"\n"
" STRUCT_OPS_MAP := [ id STRUCT_OPS_MAP_ID | name STRUCT_OPS_MAP_NAME ]\n"
" " HELP_SPEC_OPTIONS " }\n"
"",
bin_name, argv[-2]);
return 0;
}
static const struct cmd cmds[] = {
{ "show", do_show },
{ "list", do_show },
{ "register", do_register },
{ "unregister", do_unregister },
{ "dump", do_dump },
{ "help", do_help },
{ 0 }
};
int do_struct_ops(int argc, char **argv)
{
int err;
err = cmd_select(cmds, argc, argv, do_help);
btf__free(btf_vmlinux);
return err;
}
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