// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
/* Copyright (c) 2019 Netronome Systems, Inc. */
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <net/if.h>
#include <sys/utsname.h>
#include <linux/btf.h>
#include <linux/filter.h>
#include <linux/kernel.h>
#include <linux/version.h>
#include "bpf.h"
#include "libbpf.h"
#include "libbpf_internal.h"
/* On Ubuntu LINUX_VERSION_CODE doesn't correspond to info.release,
* but Ubuntu provides /proc/version_signature file, as described at
* https://ubuntu.com/kernel, with an example contents below, which we
* can use to get a proper LINUX_VERSION_CODE.
*
* Ubuntu 5.4.0-12.15-generic 5.4.8
*
* In the above, 5.4.8 is what kernel is actually expecting, while
* uname() call will return 5.4.0 in info.release.
*/
static __u32 get_ubuntu_kernel_version(void)
{
const char *ubuntu_kver_file = "/proc/version_signature";
__u32 major, minor, patch;
int ret;
FILE *f;
if (faccessat(AT_FDCWD, ubuntu_kver_file, R_OK, AT_EACCESS) != 0)
return 0;
f = fopen(ubuntu_kver_file, "re");
if (!f)
return 0;
ret = fscanf(f, "%*s %*s %u.%u.%u\n", &major, &minor, &patch);
fclose(f);
if (ret != 3)
return 0;
return KERNEL_VERSION(major, minor, patch);
}
/* On Debian LINUX_VERSION_CODE doesn't correspond to info.release.
* Instead, it is provided in info.version. An example content of
* Debian 10 looks like the below.
*
* utsname::release 4.19.0-22-amd64
* utsname::version #1 SMP Debian 4.19.260-1 (2022-09-29)
*
* In the above, 4.19.260 is what kernel is actually expecting, while
* uname() call will return 4.19.0 in info.release.
*/
static __u32 get_debian_kernel_version(struct utsname *info)
{
__u32 major, minor, patch;
char *p;
p = strstr(info->version, "Debian ");
if (!p) {
/* This is not a Debian kernel. */
return 0;
}
if (sscanf(p, "Debian %u.%u.%u", &major, &minor, &patch) != 3)
return 0;
return KERNEL_VERSION(major, minor, patch);
}
__u32 get_kernel_version(void)
{
__u32 major, minor, patch, version;
struct utsname info;
/* Check if this is an Ubuntu kernel. */
version = get_ubuntu_kernel_version();
if (version != 0)
return version;
uname(&info);
/* Check if this is a Debian kernel. */
version = get_debian_kernel_version(&info);
if (version != 0)
return version;
if (sscanf(info.release, "%u.%u.%u", &major, &minor, &patch) != 3)
return 0;
return KERNEL_VERSION(major, minor, patch);
}
static int probe_prog_load(enum bpf_prog_type prog_type,
const struct bpf_insn *insns, size_t insns_cnt,
char *log_buf, size_t log_buf_sz)
{
LIBBPF_OPTS(bpf_prog_load_opts, opts,
.log_buf = log_buf,
.log_size = log_buf_sz,
.log_level = log_buf ? 1 : 0,
);
int fd, err, exp_err = 0;
const char *exp_msg = NULL;
char buf[4096];
switch (prog_type) {
case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
opts.expected_attach_type = BPF_CGROUP_INET4_CONNECT;
break;
case BPF_PROG_TYPE_CGROUP_SOCKOPT:
opts.expected_attach_type = BPF_CGROUP_GETSOCKOPT;
break;
case BPF_PROG_TYPE_SK_LOOKUP:
opts.expected_attach_type = BPF_SK_LOOKUP;
break;
case BPF_PROG_TYPE_KPROBE:
opts.kern_version = get_kernel_version();
break;
case BPF_PROG_TYPE_LIRC_MODE2:
opts.expected_attach_type = BPF_LIRC_MODE2;
break;
case BPF_PROG_TYPE_TRACING:
case BPF_PROG_TYPE_LSM:
opts.log_buf = buf;
opts.log_size = sizeof(buf);
opts.log_level = 1;
if (prog_type == BPF_PROG_TYPE_TRACING)
opts.expected_attach_type = BPF_TRACE_FENTRY;
else
opts.expected_attach_type = BPF_MODIFY_RETURN;
opts.attach_btf_id = 1;
exp_err = -EINVAL;
exp_msg = "attach_btf_id 1 is not a function";
break;
case BPF_PROG_TYPE_EXT:
opts.log_buf = buf;
opts.log_size = sizeof(buf);
opts.log_level = 1;
opts.attach_btf_id = 1;
exp_err = -EINVAL;
exp_msg = "Cannot replace kernel functions";
break;
case BPF_PROG_TYPE_SYSCALL:
opts.prog_flags = BPF_F_SLEEPABLE;
break;
case BPF_PROG_TYPE_STRUCT_OPS:
exp_err = -524; /* -ENOTSUPP */
break;
case BPF_PROG_TYPE_UNSPEC:
case BPF_PROG_TYPE_SOCKET_FILTER:
case BPF_PROG_TYPE_SCHED_CLS:
case BPF_PROG_TYPE_SCHED_ACT:
case BPF_PROG_TYPE_TRACEPOINT:
case BPF_PROG_TYPE_XDP:
case BPF_PROG_TYPE_PERF_EVENT:
case BPF_PROG_TYPE_CGROUP_SKB:
case BPF_PROG_TYPE_CGROUP_SOCK:
case BPF_PROG_TYPE_LWT_IN:
case BPF_PROG_TYPE_LWT_OUT:
case BPF_PROG_TYPE_LWT_XMIT:
case BPF_PROG_TYPE_SOCK_OPS:
case BPF_PROG_TYPE_SK_SKB:
case BPF_PROG_TYPE_CGROUP_DEVICE:
case BPF_PROG_TYPE_SK_MSG:
case BPF_PROG_TYPE_RAW_TRACEPOINT:
case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
case BPF_PROG_TYPE_LWT_SEG6LOCAL:
case BPF_PROG_TYPE_SK_REUSEPORT:
case BPF_PROG_TYPE_FLOW_DISSECTOR:
case BPF_PROG_TYPE_CGROUP_SYSCTL:
break;
case BPF_PROG_TYPE_NETFILTER:
opts.expected_attach_type = BPF_NETFILTER;
break;
default:
return -EOPNOTSUPP;
}
fd = bpf_prog_load(prog_type, NULL, "GPL", insns, insns_cnt, &opts);
err = -errno;
if (fd >= 0)
close(fd);
if (exp_err) {
if (fd >= 0 || err != exp_err)
return 0;
if (exp_msg && !strstr(buf, exp_msg))
return 0;
return 1;
}
return fd >= 0 ? 1 : 0;
}
int libbpf_probe_bpf_prog_type(enum bpf_prog_type prog_type, const void *opts)
{
struct bpf_insn insns[] = {
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN()
};
const size_t insn_cnt = ARRAY_SIZE(insns);
int ret;
if (opts)
return libbpf_err(-EINVAL);
ret = probe_prog_load(prog_type, insns, insn_cnt, NULL, 0);
return libbpf_err(ret);
}
int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
const char *str_sec, size_t str_len,
int token_fd)
{
struct btf_header hdr = {
.magic = BTF_MAGIC,
.version = BTF_VERSION,
.hdr_len = sizeof(struct btf_header),
.type_len = types_len,
.str_off = types_len,
.str_len = str_len,
};
LIBBPF_OPTS(bpf_btf_load_opts, opts,
.token_fd = token_fd,
.btf_flags = token_fd ? BPF_F_TOKEN_FD : 0,
);
int btf_fd, btf_len;
__u8 *raw_btf;
btf_len = hdr.hdr_len + hdr.type_len + hdr.str_len;
raw_btf = malloc(btf_len);
if (!raw_btf)
return -ENOMEM;
memcpy(raw_btf, &hdr, sizeof(hdr));
memcpy(raw_btf + hdr.hdr_len, raw_types, hdr.type_len);
memcpy(raw_btf + hdr.hdr_len + hdr.type_len, str_sec, hdr.str_len);
btf_fd = bpf_btf_load(raw_btf, btf_len, &opts);
free(raw_btf);
return btf_fd;
}
static int load_local_storage_btf(void)
{
const char strs[] = "\0bpf_spin_lock\0val\0cnt\0l";
/* struct bpf_spin_lock {
* int val;
* };
* struct val {
* int cnt;
* struct bpf_spin_lock l;
* };
*/
__u32 types[] = {
/* int */
BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
/* struct bpf_spin_lock */ /* [2] */
BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 1), 4),
BTF_MEMBER_ENC(15, 1, 0), /* int val; */
/* struct val */ /* [3] */
BTF_TYPE_ENC(15, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 8),
BTF_MEMBER_ENC(19, 1, 0), /* int cnt; */
BTF_MEMBER_ENC(23, 2, 32),/* struct bpf_spin_lock l; */
};
return libbpf__load_raw_btf((char *)types, sizeof(types),
strs, sizeof(strs), 0);
}
static int probe_map_create(enum bpf_map_type map_type)
{
LIBBPF_OPTS(bpf_map_create_opts, opts);
int key_size, value_size, max_entries;
__u32 btf_key_type_id = 0, btf_value_type_id = 0;
int fd = -1, btf_fd = -1, fd_inner = -1, exp_err = 0, err = 0;
key_size = sizeof(__u32);
value_size = sizeof(__u32);
max_entries = 1;
switch (map_type) {
case BPF_MAP_TYPE_STACK_TRACE:
value_size = sizeof(__u64);
break;
case BPF_MAP_TYPE_LPM_TRIE:
key_size = sizeof(__u64);
value_size = sizeof(__u64);
opts.map_flags = BPF_F_NO_PREALLOC;
break;
case BPF_MAP_TYPE_CGROUP_STORAGE:
case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE:
key_size = sizeof(struct bpf_cgroup_storage_key);
value_size = sizeof(__u64);
max_entries = 0;
break;
case BPF_MAP_TYPE_QUEUE:
case BPF_MAP_TYPE_STACK:
key_size = 0;
break;
case BPF_MAP_TYPE_SK_STORAGE:
case BPF_MAP_TYPE_INODE_STORAGE:
case BPF_MAP_TYPE_TASK_STORAGE:
case BPF_MAP_TYPE_CGRP_STORAGE:
btf_key_type_id = 1;
btf_value_type_id = 3;
value_size = 8;
max_entries = 0;
opts.map_flags = BPF_F_NO_PREALLOC;
btf_fd = load_local_storage_btf();
if (btf_fd < 0)
return btf_fd;
break;
case BPF_MAP_TYPE_RINGBUF:
case BPF_MAP_TYPE_USER_RINGBUF:
key_size = 0;
value_size = 0;
max_entries = sysconf(_SC_PAGE_SIZE);
break;
case BPF_MAP_TYPE_STRUCT_OPS:
/* we'll get -ENOTSUPP for invalid BTF type ID for struct_ops */
opts.btf_vmlinux_value_type_id = 1;
opts.value_type_btf_obj_fd = -1;
exp_err = -524; /* -ENOTSUPP */
break;
case BPF_MAP_TYPE_BLOOM_FILTER:
key_size = 0;
max_entries = 1;
break;
case BPF_MAP_TYPE_ARENA:
key_size = 0;
value_size = 0;
max_entries = 1; /* one page */
opts.map_extra = 0; /* can mmap() at any address */
opts.map_flags = BPF_F_MMAPABLE;
break;
case BPF_MAP_TYPE_HASH:
case BPF_MAP_TYPE_ARRAY:
case BPF_MAP_TYPE_PROG_ARRAY:
case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
case BPF_MAP_TYPE_PERCPU_HASH:
case BPF_MAP_TYPE_PERCPU_ARRAY:
case BPF_MAP_TYPE_CGROUP_ARRAY:
case BPF_MAP_TYPE_LRU_HASH:
case BPF_MAP_TYPE_LRU_PERCPU_HASH:
case BPF_MAP_TYPE_ARRAY_OF_MAPS:
case BPF_MAP_TYPE_HASH_OF_MAPS:
case BPF_MAP_TYPE_DEVMAP:
case BPF_MAP_TYPE_DEVMAP_HASH:
case BPF_MAP_TYPE_SOCKMAP:
case BPF_MAP_TYPE_CPUMAP:
case BPF_MAP_TYPE_XSKMAP:
case BPF_MAP_TYPE_SOCKHASH:
case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
break;
case BPF_MAP_TYPE_UNSPEC:
default:
return -EOPNOTSUPP;
}
if (map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
fd_inner = bpf_map_create(BPF_MAP_TYPE_HASH, NULL,
sizeof(__u32), sizeof(__u32), 1, NULL);
if (fd_inner < 0)
goto cleanup;
opts.inner_map_fd = fd_inner;
}
if (btf_fd >= 0) {
opts.btf_fd = btf_fd;
opts.btf_key_type_id = btf_key_type_id;
opts.btf_value_type_id = btf_value_type_id;
}
fd = bpf_map_create(map_type, NULL, key_size, value_size, max_entries, &opts);
err = -errno;
cleanup:
if (fd >= 0)
close(fd);
if (fd_inner >= 0)
close(fd_inner);
if (btf_fd >= 0)
close(btf_fd);
if (exp_err)
return fd < 0 && err == exp_err ? 1 : 0;
else
return fd >= 0 ? 1 : 0;
}
int libbpf_probe_bpf_map_type(enum bpf_map_type map_type, const void *opts)
{
int ret;
if (opts)
return libbpf_err(-EINVAL);
ret = probe_map_create(map_type);
return libbpf_err(ret);
}
int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type, enum bpf_func_id helper_id,
const void *opts)
{
struct bpf_insn insns[] = {
BPF_EMIT_CALL((__u32)helper_id),
BPF_EXIT_INSN(),
};
const size_t insn_cnt = ARRAY_SIZE(insns);
char buf[4096];
int ret;
if (opts)
return libbpf_err(-EINVAL);
/* we can't successfully load all prog types to check for BPF helper
* support, so bail out with -EOPNOTSUPP error
*/
switch (prog_type) {
case BPF_PROG_TYPE_TRACING:
case BPF_PROG_TYPE_EXT:
case BPF_PROG_TYPE_LSM:
case BPF_PROG_TYPE_STRUCT_OPS:
return -EOPNOTSUPP;
default:
break;
}
buf[0] = '\0';
ret = probe_prog_load(prog_type, insns, insn_cnt, buf, sizeof(buf));
if (ret < 0)
return libbpf_err(ret);
/* If BPF verifier doesn't recognize BPF helper ID (enum bpf_func_id)
* at all, it will emit something like "invalid func unknown#181".
* If BPF verifier recognizes BPF helper but it's not supported for
* given BPF program type, it will emit "unknown func bpf_sys_bpf#166"
* or "program of this type cannot use helper bpf_sys_bpf#166".
* In both cases, provided combination of BPF program type and BPF
* helper is not supported by the kernel.
* In all other cases, probe_prog_load() above will either succeed (e.g.,
* because BPF helper happens to accept no input arguments or it
* accepts one input argument and initial PTR_TO_CTX is fine for
* that), or we'll get some more specific BPF verifier error about
* some unsatisfied conditions.
*/
if (ret == 0 && (strstr(buf, "invalid func ") || strstr(buf, "unknown func ") ||
strstr(buf, "program of this type cannot use helper ")))
return 0;
return 1; /* assume supported */
}
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