linux/tools/lib/bpf/btf.c

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// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
/* Copyright (c) 2018 Facebook */
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <linux/err.h>
#include <linux/btf.h>
#include "btf.h"
#include "bpf.h"
#define elog(fmt, ...) { if (err_log) err_log(fmt, ##__VA_ARGS__); }
#define max(a, b) ((a) > (b) ? (a) : (b))
#define min(a, b) ((a) < (b) ? (a) : (b))
#define BTF_MAX_NR_TYPES 65535
#define IS_MODIFIER(k) (((k) == BTF_KIND_TYPEDEF) || \
((k) == BTF_KIND_VOLATILE) || \
((k) == BTF_KIND_CONST) || \
((k) == BTF_KIND_RESTRICT))
static struct btf_type btf_void;
struct btf {
union {
struct btf_header *hdr;
void *data;
};
struct btf_type **types;
const char *strings;
void *nohdr_data;
__u32 nr_types;
__u32 types_size;
__u32 data_size;
int fd;
};
struct btf_ext {
void *func_info;
__u32 func_info_rec_size;
__u32 func_info_len;
};
/* The minimum bpf_func_info checked by the loader */
struct bpf_func_info_min {
__u32 insn_offset;
__u32 type_id;
};
static inline __u64 ptr_to_u64(const void *ptr)
{
return (__u64) (unsigned long) ptr;
}
static int btf_add_type(struct btf *btf, struct btf_type *t)
{
if (btf->types_size - btf->nr_types < 2) {
struct btf_type **new_types;
__u32 expand_by, new_size;
if (btf->types_size == BTF_MAX_NR_TYPES)
return -E2BIG;
expand_by = max(btf->types_size >> 2, 16);
new_size = min(BTF_MAX_NR_TYPES, btf->types_size + expand_by);
new_types = realloc(btf->types, sizeof(*new_types) * new_size);
if (!new_types)
return -ENOMEM;
if (btf->nr_types == 0)
new_types[0] = &btf_void;
btf->types = new_types;
btf->types_size = new_size;
}
btf->types[++(btf->nr_types)] = t;
return 0;
}
static int btf_parse_hdr(struct btf *btf, btf_print_fn_t err_log)
{
const struct btf_header *hdr = btf->hdr;
__u32 meta_left;
if (btf->data_size < sizeof(struct btf_header)) {
elog("BTF header not found\n");
return -EINVAL;
}
if (hdr->magic != BTF_MAGIC) {
elog("Invalid BTF magic:%x\n", hdr->magic);
return -EINVAL;
}
if (hdr->version != BTF_VERSION) {
elog("Unsupported BTF version:%u\n", hdr->version);
return -ENOTSUP;
}
if (hdr->flags) {
elog("Unsupported BTF flags:%x\n", hdr->flags);
return -ENOTSUP;
}
meta_left = btf->data_size - sizeof(*hdr);
if (!meta_left) {
elog("BTF has no data\n");
return -EINVAL;
}
if (meta_left < hdr->type_off) {
elog("Invalid BTF type section offset:%u\n", hdr->type_off);
return -EINVAL;
}
if (meta_left < hdr->str_off) {
elog("Invalid BTF string section offset:%u\n", hdr->str_off);
return -EINVAL;
}
if (hdr->type_off >= hdr->str_off) {
elog("BTF type section offset >= string section offset. No type?\n");
return -EINVAL;
}
if (hdr->type_off & 0x02) {
elog("BTF type section is not aligned to 4 bytes\n");
return -EINVAL;
}
btf->nohdr_data = btf->hdr + 1;
return 0;
}
static int btf_parse_str_sec(struct btf *btf, btf_print_fn_t err_log)
{
const struct btf_header *hdr = btf->hdr;
const char *start = btf->nohdr_data + hdr->str_off;
const char *end = start + btf->hdr->str_len;
if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_NAME_OFFSET ||
start[0] || end[-1]) {
elog("Invalid BTF string section\n");
return -EINVAL;
}
btf->strings = start;
return 0;
}
static int btf_parse_type_sec(struct btf *btf, btf_print_fn_t err_log)
{
struct btf_header *hdr = btf->hdr;
void *nohdr_data = btf->nohdr_data;
void *next_type = nohdr_data + hdr->type_off;
void *end_type = nohdr_data + hdr->str_off;
while (next_type < end_type) {
struct btf_type *t = next_type;
__u16 vlen = BTF_INFO_VLEN(t->info);
int err;
next_type += sizeof(*t);
switch (BTF_INFO_KIND(t->info)) {
case BTF_KIND_INT:
next_type += sizeof(int);
break;
case BTF_KIND_ARRAY:
next_type += sizeof(struct btf_array);
break;
case BTF_KIND_STRUCT:
case BTF_KIND_UNION:
next_type += vlen * sizeof(struct btf_member);
break;
case BTF_KIND_ENUM:
next_type += vlen * sizeof(struct btf_enum);
break;
case BTF_KIND_FUNC_PROTO:
next_type += vlen * sizeof(struct btf_param);
break;
case BTF_KIND_FUNC:
case BTF_KIND_TYPEDEF:
case BTF_KIND_PTR:
case BTF_KIND_FWD:
case BTF_KIND_VOLATILE:
case BTF_KIND_CONST:
case BTF_KIND_RESTRICT:
break;
default:
elog("Unsupported BTF_KIND:%u\n",
BTF_INFO_KIND(t->info));
return -EINVAL;
}
err = btf_add_type(btf, t);
if (err)
return err;
}
return 0;
}
const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 type_id)
{
if (type_id > btf->nr_types)
return NULL;
return btf->types[type_id];
}
static bool btf_type_is_void(const struct btf_type *t)
{
return t == &btf_void || BTF_INFO_KIND(t->info) == BTF_KIND_FWD;
}
static bool btf_type_is_void_or_null(const struct btf_type *t)
{
return !t || btf_type_is_void(t);
}
static __s64 btf_type_size(const struct btf_type *t)
{
switch (BTF_INFO_KIND(t->info)) {
case BTF_KIND_INT:
case BTF_KIND_STRUCT:
case BTF_KIND_UNION:
case BTF_KIND_ENUM:
return t->size;
case BTF_KIND_PTR:
return sizeof(void *);
default:
return -EINVAL;
}
}
#define MAX_RESOLVE_DEPTH 32
__s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
{
const struct btf_array *array;
const struct btf_type *t;
__u32 nelems = 1;
__s64 size = -1;
int i;
t = btf__type_by_id(btf, type_id);
for (i = 0; i < MAX_RESOLVE_DEPTH && !btf_type_is_void_or_null(t);
i++) {
size = btf_type_size(t);
if (size >= 0)
break;
switch (BTF_INFO_KIND(t->info)) {
case BTF_KIND_TYPEDEF:
case BTF_KIND_VOLATILE:
case BTF_KIND_CONST:
case BTF_KIND_RESTRICT:
type_id = t->type;
break;
case BTF_KIND_ARRAY:
array = (const struct btf_array *)(t + 1);
if (nelems && array->nelems > UINT32_MAX / nelems)
return -E2BIG;
nelems *= array->nelems;
type_id = array->type;
break;
default:
return -EINVAL;
}
t = btf__type_by_id(btf, type_id);
}
if (size < 0)
return -EINVAL;
if (nelems && size > UINT32_MAX / nelems)
return -E2BIG;
return nelems * size;
}
int btf__resolve_type(const struct btf *btf, __u32 type_id)
{
const struct btf_type *t;
int depth = 0;
t = btf__type_by_id(btf, type_id);
while (depth < MAX_RESOLVE_DEPTH &&
!btf_type_is_void_or_null(t) &&
IS_MODIFIER(BTF_INFO_KIND(t->info))) {
type_id = t->type;
t = btf__type_by_id(btf, type_id);
depth++;
}
if (depth == MAX_RESOLVE_DEPTH || btf_type_is_void_or_null(t))
return -EINVAL;
return type_id;
}
__s32 btf__find_by_name(const struct btf *btf, const char *type_name)
{
__u32 i;
if (!strcmp(type_name, "void"))
return 0;
for (i = 1; i <= btf->nr_types; i++) {
const struct btf_type *t = btf->types[i];
const char *name = btf__name_by_offset(btf, t->name_off);
if (name && !strcmp(type_name, name))
return i;
}
return -ENOENT;
}
void btf__free(struct btf *btf)
{
if (!btf)
return;
if (btf->fd != -1)
close(btf->fd);
free(btf->data);
free(btf->types);
free(btf);
}
struct btf *btf__new(__u8 *data, __u32 size, btf_print_fn_t err_log)
{
__u32 log_buf_size = 0;
char *log_buf = NULL;
struct btf *btf;
int err;
btf = calloc(1, sizeof(struct btf));
if (!btf)
return ERR_PTR(-ENOMEM);
btf->fd = -1;
if (err_log) {
log_buf = malloc(BPF_LOG_BUF_SIZE);
if (!log_buf) {
err = -ENOMEM;
goto done;
}
*log_buf = 0;
log_buf_size = BPF_LOG_BUF_SIZE;
}
btf->data = malloc(size);
if (!btf->data) {
err = -ENOMEM;
goto done;
}
memcpy(btf->data, data, size);
btf->data_size = size;
btf->fd = bpf_load_btf(btf->data, btf->data_size,
log_buf, log_buf_size, false);
if (btf->fd == -1) {
err = -errno;
elog("Error loading BTF: %s(%d)\n", strerror(errno), errno);
if (log_buf && *log_buf)
elog("%s\n", log_buf);
goto done;
}
err = btf_parse_hdr(btf, err_log);
if (err)
goto done;
err = btf_parse_str_sec(btf, err_log);
if (err)
goto done;
err = btf_parse_type_sec(btf, err_log);
done:
free(log_buf);
if (err) {
btf__free(btf);
return ERR_PTR(err);
}
return btf;
}
int btf__fd(const struct btf *btf)
{
return btf->fd;
}
const char *btf__name_by_offset(const struct btf *btf, __u32 offset)
{
if (offset < btf->hdr->str_len)
return &btf->strings[offset];
else
return NULL;
}
int btf__get_from_id(__u32 id, struct btf **btf)
{
struct bpf_btf_info btf_info = { 0 };
__u32 len = sizeof(btf_info);
__u32 last_size;
int btf_fd;
void *ptr;
int err;
err = 0;
*btf = NULL;
btf_fd = bpf_btf_get_fd_by_id(id);
if (btf_fd < 0)
return 0;
/* we won't know btf_size until we call bpf_obj_get_info_by_fd(). so
* let's start with a sane default - 4KiB here - and resize it only if
* bpf_obj_get_info_by_fd() needs a bigger buffer.
*/
btf_info.btf_size = 4096;
last_size = btf_info.btf_size;
ptr = malloc(last_size);
if (!ptr) {
err = -ENOMEM;
goto exit_free;
}
bzero(ptr, last_size);
btf_info.btf = ptr_to_u64(ptr);
err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
if (!err && btf_info.btf_size > last_size) {
void *temp_ptr;
last_size = btf_info.btf_size;
temp_ptr = realloc(ptr, last_size);
if (!temp_ptr) {
err = -ENOMEM;
goto exit_free;
}
ptr = temp_ptr;
bzero(ptr, last_size);
btf_info.btf = ptr_to_u64(ptr);
err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
}
if (err || btf_info.btf_size > last_size) {
err = errno;
goto exit_free;
}
*btf = btf__new((__u8 *)btf_info.btf, btf_info.btf_size, NULL);
if (IS_ERR(*btf)) {
err = PTR_ERR(*btf);
*btf = NULL;
}
exit_free:
close(btf_fd);
free(ptr);
return err;
}
static int btf_ext_validate_func_info(const void *finfo, __u32 size,
btf_print_fn_t err_log)
{
int sec_hdrlen = sizeof(struct btf_sec_func_info);
__u32 size_left, num_records, record_size;
const struct btf_sec_func_info *sinfo;
__u64 total_record_size;
/* At least a func_info record size */
if (size < sizeof(__u32)) {
elog("BTF.ext func_info record size not found");
return -EINVAL;
}
/* The record size needs to meet below minimum standard */
record_size = *(__u32 *)finfo;
if (record_size < sizeof(struct bpf_func_info_min) ||
record_size % sizeof(__u32)) {
elog("BTF.ext func_info invalid record size");
return -EINVAL;
}
sinfo = finfo + sizeof(__u32);
size_left = size - sizeof(__u32);
/* If no func_info records, return failure now so .BTF.ext
* won't be used.
*/
if (!size_left) {
elog("BTF.ext no func info records");
return -EINVAL;
}
while (size_left) {
if (size_left < sec_hdrlen) {
elog("BTF.ext func_info header not found");
return -EINVAL;
}
num_records = sinfo->num_func_info;
if (num_records == 0) {
elog("incorrect BTF.ext num_func_info");
return -EINVAL;
}
total_record_size = sec_hdrlen +
(__u64)num_records * record_size;
if (size_left < total_record_size) {
elog("incorrect BTF.ext num_func_info");
return -EINVAL;
}
size_left -= total_record_size;
sinfo = (void *)sinfo + total_record_size;
}
return 0;
}
static int btf_ext_parse_hdr(__u8 *data, __u32 data_size,
btf_print_fn_t err_log)
{
const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
__u32 meta_left, last_func_info_pos;
void *finfo;
if (data_size < offsetof(struct btf_ext_header, func_info_off) ||
data_size < hdr->hdr_len) {
elog("BTF.ext header not found");
return -EINVAL;
}
if (hdr->magic != BTF_MAGIC) {
elog("Invalid BTF.ext magic:%x\n", hdr->magic);
return -EINVAL;
}
if (hdr->version != BTF_VERSION) {
elog("Unsupported BTF.ext version:%u\n", hdr->version);
return -ENOTSUP;
}
if (hdr->flags) {
elog("Unsupported BTF.ext flags:%x\n", hdr->flags);
return -ENOTSUP;
}
meta_left = data_size - hdr->hdr_len;
if (!meta_left) {
elog("BTF.ext has no data\n");
return -EINVAL;
}
if (meta_left < hdr->func_info_off) {
elog("Invalid BTF.ext func_info section offset:%u\n",
hdr->func_info_off);
return -EINVAL;
}
if (hdr->func_info_off & 0x03) {
elog("BTF.ext func_info section is not aligned to 4 bytes\n");
return -EINVAL;
}
last_func_info_pos = hdr->hdr_len + hdr->func_info_off +
hdr->func_info_len;
if (last_func_info_pos > data_size) {
elog("Invalid BTF.ext func_info section size:%u\n",
hdr->func_info_len);
return -EINVAL;
}
finfo = data + hdr->hdr_len + hdr->func_info_off;
return btf_ext_validate_func_info(finfo, hdr->func_info_len,
err_log);
}
void btf_ext__free(struct btf_ext *btf_ext)
{
if (!btf_ext)
return;
free(btf_ext->func_info);
free(btf_ext);
}
struct btf_ext *btf_ext__new(__u8 *data, __u32 size, btf_print_fn_t err_log)
{
const struct btf_ext_header *hdr;
struct btf_ext *btf_ext;
void *org_fdata, *fdata;
__u32 hdrlen, size_u32;
int err;
err = btf_ext_parse_hdr(data, size, err_log);
if (err)
return ERR_PTR(err);
btf_ext = calloc(1, sizeof(struct btf_ext));
if (!btf_ext)
return ERR_PTR(-ENOMEM);
hdr = (const struct btf_ext_header *)data;
hdrlen = hdr->hdr_len;
size_u32 = sizeof(__u32);
fdata = malloc(hdr->func_info_len - size_u32);
if (!fdata) {
free(btf_ext);
return ERR_PTR(-ENOMEM);
}
/* remember record size and copy rest of func_info data */
org_fdata = data + hdrlen + hdr->func_info_off;
btf_ext->func_info_rec_size = *(__u32 *)org_fdata;
memcpy(fdata, org_fdata + size_u32, hdr->func_info_len - size_u32);
btf_ext->func_info = fdata;
btf_ext->func_info_len = hdr->func_info_len - size_u32;
return btf_ext;
}
int btf_ext__reloc_init(struct btf *btf, struct btf_ext *btf_ext,
const char *sec_name, void **func_info,
__u32 *func_info_rec_size, __u32 *func_info_len)
{
__u32 sec_hdrlen = sizeof(struct btf_sec_func_info);
__u32 i, record_size, records_len;
struct btf_sec_func_info *sinfo;
const char *info_sec_name;
__s64 remain_len;
void *data;
record_size = btf_ext->func_info_rec_size;
sinfo = btf_ext->func_info;
remain_len = btf_ext->func_info_len;
while (remain_len > 0) {
records_len = sinfo->num_func_info * record_size;
info_sec_name = btf__name_by_offset(btf, sinfo->sec_name_off);
if (strcmp(info_sec_name, sec_name)) {
remain_len -= sec_hdrlen + records_len;
sinfo = (void *)sinfo + sec_hdrlen + records_len;
continue;
}
data = malloc(records_len);
if (!data)
return -ENOMEM;
memcpy(data, sinfo->data, records_len);
/* adjust the insn_offset, the data in .BTF.ext is
* the actual byte offset, and the kernel expects
* the offset in term of bpf_insn.
*
* adjust the insn offset only, the rest data will
* be passed to kernel.
*/
for (i = 0; i < sinfo->num_func_info; i++) {
struct bpf_func_info_min *record;
record = data + i * record_size;
record->insn_offset /= sizeof(struct bpf_insn);
}
*func_info = data;
*func_info_len = records_len;
*func_info_rec_size = record_size;
return 0;
}
return -EINVAL;
}
int btf_ext__reloc(struct btf *btf, struct btf_ext *btf_ext,
const char *sec_name, __u32 insns_cnt,
void **func_info, __u32 *func_info_len)
{
__u32 sec_hdrlen = sizeof(struct btf_sec_func_info);
__u32 i, record_size, existing_flen, records_len;
struct btf_sec_func_info *sinfo;
const char *info_sec_name;
__u64 remain_len;
void *data;
record_size = btf_ext->func_info_rec_size;
sinfo = btf_ext->func_info;
remain_len = btf_ext->func_info_len;
while (remain_len > 0) {
records_len = sinfo->num_func_info * record_size;
info_sec_name = btf__name_by_offset(btf, sinfo->sec_name_off);
if (strcmp(info_sec_name, sec_name)) {
remain_len -= sec_hdrlen + records_len;
sinfo = (void *)sinfo + sec_hdrlen + records_len;
continue;
}
existing_flen = *func_info_len;
data = realloc(*func_info, existing_flen + records_len);
if (!data)
return -ENOMEM;
memcpy(data + existing_flen, sinfo->data, records_len);
/* adjust insn_offset only, the rest data will be passed
* to the kernel.
*/
for (i = 0; i < sinfo->num_func_info; i++) {
struct bpf_func_info_min *record;
record = data + existing_flen + i * record_size;
record->insn_offset =
record->insn_offset / sizeof(struct bpf_insn) +
insns_cnt;
}
*func_info = data;
*func_info_len = existing_flen + records_len;
return 0;
}
return -EINVAL;
}