// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
/* Copyright (c) 2019 Netronome Systems, Inc. */
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <net/if.h>
#ifdef USE_LIBCAP
#include <sys/capability.h>
#endif
#include <sys/utsname.h>
#include <sys/vfs.h>
#include <linux/filter.h>
#include <linux/limits.h>
#include <bpf/bpf.h>
#include <bpf/libbpf.h>
#include <zlib.h>
#include "main.h"
#ifndef PROC_SUPER_MAGIC
# define PROC_SUPER_MAGIC 0x9fa0
#endif
enum probe_component {
COMPONENT_UNSPEC,
COMPONENT_KERNEL,
COMPONENT_DEVICE,
};
#define BPF_HELPER_MAKE_ENTRY(name) [BPF_FUNC_ ## name] = "bpf_" # name
static const char * const helper_name[] = {
__BPF_FUNC_MAPPER(BPF_HELPER_MAKE_ENTRY)
};
#undef BPF_HELPER_MAKE_ENTRY
static bool full_mode;
#ifdef USE_LIBCAP
static bool run_as_unprivileged;
#endif
/* Miscellaneous utility functions */
static bool grep(const char *buffer, const char *pattern)
{
return !!strstr(buffer, pattern);
}
static bool check_procfs(void)
{
struct statfs st_fs;
if (statfs("/proc", &st_fs) < 0)
return false;
if ((unsigned long)st_fs.f_type != PROC_SUPER_MAGIC)
return false;
return true;
}
static void uppercase(char *str, size_t len)
{
size_t i;
for (i = 0; i < len && str[i] != '\0'; i++)
str[i] = toupper(str[i]);
}
/* Printing utility functions */
static void
print_bool_feature(const char *feat_name, const char *plain_name,
const char *define_name, bool res, const char *define_prefix)
{
if (json_output)
jsonw_bool_field(json_wtr, feat_name, res);
else if (define_prefix)
printf("#define %s%sHAVE_%s\n", define_prefix,
res ? "" : "NO_", define_name);
else
printf("%s is %savailable\n", plain_name, res ? "" : "NOT ");
}
static void print_kernel_option(const char *name, const char *value,
const char *define_prefix)
{
char *endptr;
int res;
if (json_output) {
if (!value) {
jsonw_null_field(json_wtr, name);
return;
}
errno = 0;
res = strtol(value, &endptr, 0);
if (!errno && *endptr == '\n')
jsonw_int_field(json_wtr, name, res);
else
jsonw_string_field(json_wtr, name, value);
} else if (define_prefix) {
if (value)
printf("#define %s%s %s\n", define_prefix,
name, value);
else
printf("/* %s%s is not set */\n", define_prefix, name);
} else {
if (value)
printf("%s is set to %s\n", name, value);
else
printf("%s is not set\n", name);
}
}
static void
print_start_section(const char *json_title, const char *plain_title,
const char *define_comment, const char *define_prefix)
{
if (json_output) {
jsonw_name(json_wtr, json_title);
jsonw_start_object(json_wtr);
} else if (define_prefix) {
printf("%s\n", define_comment);
} else {
printf("%s\n", plain_title);
}
}
static void print_end_section(void)
{
if (json_output)
jsonw_end_object(json_wtr);
else
printf("\n");
}
/* Probing functions */
static int get_vendor_id(int ifindex)
{
char ifname[IF_NAMESIZE], path[64], buf[8];
ssize_t len;
int fd;
if (!if_indextoname(ifindex, ifname))
return -1;
snprintf(path, sizeof(path), "/sys/class/net/%s/device/vendor", ifname);
fd = open(path, O_RDONLY | O_CLOEXEC);
if (fd < 0)
return -1;
len = read(fd, buf, sizeof(buf));
close(fd);
if (len < 0)
return -1;
if (len >= (ssize_t)sizeof(buf))
return -1;
buf[len] = '\0';
return strtol(buf, NULL, 0);
}
static long read_procfs(const char *path)
{
char *endptr, *line = NULL;
size_t len = 0;
FILE *fd;
long res;
fd = fopen(path, "r");
if (!fd)
return -1;
res = getline(&line, &len, fd);
fclose(fd);
if (res < 0)
return -1;
errno = 0;
res = strtol(line, &endptr, 10);
if (errno || *line == '\0' || *endptr != '\n')
res = -1;
free(line);
return res;
}
static void probe_unprivileged_disabled(void)
{
long res;
/* No support for C-style output */
res = read_procfs("/proc/sys/kernel/unprivileged_bpf_disabled");
if (json_output) {
jsonw_int_field(json_wtr, "unprivileged_bpf_disabled", res);
} else {
switch (res) {
case 0:
printf("bpf() syscall for unprivileged users is enabled\n");
break;
case 1:
printf("bpf() syscall restricted to privileged users (without recovery)\n");
break;
case 2:
printf("bpf() syscall restricted to privileged users (admin can change)\n");
break;
case -1:
printf("Unable to retrieve required privileges for bpf() syscall\n");
break;
default:
printf("bpf() syscall restriction has unknown value %ld\n", res);
}
}
}
static void probe_jit_enable(void)
{
long res;
/* No support for C-style output */
res = read_procfs("/proc/sys/net/core/bpf_jit_enable");
if (json_output) {
jsonw_int_field(json_wtr, "bpf_jit_enable", res);
} else {
switch (res) {
case 0:
printf("JIT compiler is disabled\n");
break;
case 1:
printf("JIT compiler is enabled\n");
break;
case 2:
printf("JIT compiler is enabled with debugging traces in kernel logs\n");
break;
case -1:
printf("Unable to retrieve JIT-compiler status\n");
break;
default:
printf("JIT-compiler status has unknown value %ld\n",
res);
}
}
}
static void probe_jit_harden(void)
{
long res;
/* No support for C-style output */
res = read_procfs("/proc/sys/net/core/bpf_jit_harden");
if (json_output) {
jsonw_int_field(json_wtr, "bpf_jit_harden", res);
} else {
switch (res) {
case 0:
printf("JIT compiler hardening is disabled\n");
break;
case 1:
printf("JIT compiler hardening is enabled for unprivileged users\n");
break;
case 2:
printf("JIT compiler hardening is enabled for all users\n");
break;
case -1:
printf("Unable to retrieve JIT hardening status\n");
break;
default:
printf("JIT hardening status has unknown value %ld\n",
res);
}
}
}
static void probe_jit_kallsyms(void)
{
long res;
/* No support for C-style output */
res = read_procfs("/proc/sys/net/core/bpf_jit_kallsyms");
if (json_output) {
jsonw_int_field(json_wtr, "bpf_jit_kallsyms", res);
} else {
switch (res) {
case 0:
printf("JIT compiler kallsyms exports are disabled\n");
break;
case 1:
printf("JIT compiler kallsyms exports are enabled for root\n");
break;
case -1:
printf("Unable to retrieve JIT kallsyms export status\n");
break;
default:
printf("JIT kallsyms exports status has unknown value %ld\n", res);
}
}
}
static void probe_jit_limit(void)
{
long res;
/* No support for C-style output */
res = read_procfs("/proc/sys/net/core/bpf_jit_limit");
if (json_output) {
jsonw_int_field(json_wtr, "bpf_jit_limit", res);
} else {
switch (res) {
case -1:
printf("Unable to retrieve global memory limit for JIT compiler for unprivileged users\n");
break;
default:
printf("Global memory limit for JIT compiler for unprivileged users is %ld bytes\n", res);
}
}
}
static bool read_next_kernel_config_option(gzFile file, char *buf, size_t n,
char **value)
{
char *sep;
while (gzgets(file, buf, n)) {
if (strncmp(buf, "CONFIG_", 7))
continue;
sep = strchr(buf, '=');
if (!sep)
continue;
/* Trim ending '\n' */
buf[strlen(buf) - 1] = '\0';
/* Split on '=' and ensure that a value is present. */
*sep = '\0';
if (!sep[1])
continue;
*value = sep + 1;
return true;
}
return false;
}
static void probe_kernel_image_config(const char *define_prefix)
{
static const struct {
const char * const name;
bool macro_dump;
} options[] = {
/* Enable BPF */
{ "CONFIG_BPF", },
/* Enable bpf() syscall */
{ "CONFIG_BPF_SYSCALL", },
/* Does selected architecture support eBPF JIT compiler */
{ "CONFIG_HAVE_EBPF_JIT", },
/* Compile eBPF JIT compiler */
{ "CONFIG_BPF_JIT", },
/* Avoid compiling eBPF interpreter (use JIT only) */
{ "CONFIG_BPF_JIT_ALWAYS_ON", },
/* Kernel BTF debug information available */
{ "CONFIG_DEBUG_INFO_BTF", },
/* Kernel module BTF debug information available */
{ "CONFIG_DEBUG_INFO_BTF_MODULES", },
/* cgroups */
{ "CONFIG_CGROUPS", },
/* BPF programs attached to cgroups */
{ "CONFIG_CGROUP_BPF", },
/* bpf_get_cgroup_classid() helper */
{ "CONFIG_CGROUP_NET_CLASSID", },
/* bpf_skb_{,ancestor_}cgroup_id() helpers */
{ "CONFIG_SOCK_CGROUP_DATA", },
/* Tracing: attach BPF to kprobes, tracepoints, etc. */
{ "CONFIG_BPF_EVENTS", },
/* Kprobes */
{ "CONFIG_KPROBE_EVENTS", },
/* Uprobes */
{ "CONFIG_UPROBE_EVENTS", },
/* Tracepoints */
{ "CONFIG_TRACING", },
/* Syscall tracepoints */
{ "CONFIG_FTRACE_SYSCALLS", },
/* bpf_override_return() helper support for selected arch */
{ "CONFIG_FUNCTION_ERROR_INJECTION", },
/* bpf_override_return() helper */
{ "CONFIG_BPF_KPROBE_OVERRIDE", },
/* Network */
{ "CONFIG_NET", },
/* AF_XDP sockets */
{ "CONFIG_XDP_SOCKETS", },
/* BPF_PROG_TYPE_LWT_* and related helpers */
{ "CONFIG_LWTUNNEL_BPF", },
/* BPF_PROG_TYPE_SCHED_ACT, TC (traffic control) actions */
{ "CONFIG_NET_ACT_BPF", },
/* BPF_PROG_TYPE_SCHED_CLS, TC filters */
{ "CONFIG_NET_CLS_BPF", },
/* TC clsact qdisc */
{ "CONFIG_NET_CLS_ACT", },
/* Ingress filtering with TC */
{ "CONFIG_NET_SCH_INGRESS", },
/* bpf_skb_get_xfrm_state() helper */
{ "CONFIG_XFRM", },
/* bpf_get_route_realm() helper */
{ "CONFIG_IP_ROUTE_CLASSID", },
/* BPF_PROG_TYPE_LWT_SEG6_LOCAL and related helpers */
{ "CONFIG_IPV6_SEG6_BPF", },
/* BPF_PROG_TYPE_LIRC_MODE2 and related helpers */
{ "CONFIG_BPF_LIRC_MODE2", },
/* BPF stream parser and BPF socket maps */
{ "CONFIG_BPF_STREAM_PARSER", },
/* xt_bpf module for passing BPF programs to netfilter */
{ "CONFIG_NETFILTER_XT_MATCH_BPF", },
/* test_bpf module for BPF tests */
{ "CONFIG_TEST_BPF", },
/* Misc configs useful in BPF C programs */
/* jiffies <-> sec conversion for bpf_jiffies64() helper */
{ "CONFIG_HZ", true, }
};
char *values[ARRAY_SIZE(options)] = { };
struct utsname utsn;
char path[PATH_MAX];
gzFile file = NULL;
char buf[4096];
char *value;
size_t i;
if (!uname(&utsn)) {
snprintf(path, sizeof(path), "/boot/config-%s", utsn.release);
/* gzopen also accepts uncompressed files. */
file = gzopen(path, "r");
}
if (!file) {
/* Some distributions build with CONFIG_IKCONFIG=y and put the
* config file at /proc/config.gz.
*/
file = gzopen("/proc/config.gz", "r");
}
if (!file) {
p_info("skipping kernel config, can't open file: %s",
strerror(errno));
goto end_parse;
}
/* Sanity checks */
if (!gzgets(file, buf, sizeof(buf)) ||
!gzgets(file, buf, sizeof(buf))) {
p_info("skipping kernel config, can't read from file: %s",
strerror(errno));
goto end_parse;
}
if (strcmp(buf, "# Automatically generated file; DO NOT EDIT.\n")) {
p_info("skipping kernel config, can't find correct file");
goto end_parse;
}
while (read_next_kernel_config_option(file, buf, sizeof(buf), &value)) {
for (i = 0; i < ARRAY_SIZE(options); i++) {
if ((define_prefix && !options[i].macro_dump) ||
values[i] || strcmp(buf, options[i].name))
continue;
values[i] = strdup(value);
}
}
for (i = 0; i < ARRAY_SIZE(options); i++) {
if (define_prefix && !options[i].macro_dump)
continue;
print_kernel_option(options[i].name, values[i], define_prefix);
free(values[i]);
}
end_parse:
if (file)
gzclose(file);
}
static bool probe_bpf_syscall(const char *define_prefix)
{
bool res;
bpf_prog_load(BPF_PROG_TYPE_UNSPEC, NULL, NULL, NULL, 0, NULL);
res = (errno != ENOSYS);
print_bool_feature("have_bpf_syscall",
"bpf() syscall",
"BPF_SYSCALL",
res, define_prefix);
return res;
}
static bool
probe_prog_load_ifindex(enum bpf_prog_type prog_type,
const struct bpf_insn *insns, size_t insns_cnt,
char *log_buf, size_t log_buf_sz,
__u32 ifindex)
{
LIBBPF_OPTS(bpf_prog_load_opts, opts,
.log_buf = log_buf,
.log_size = log_buf_sz,
.log_level = log_buf ? 1 : 0,
.prog_ifindex = ifindex,
);
int fd;
errno = 0;
fd = bpf_prog_load(prog_type, NULL, "GPL", insns, insns_cnt, &opts);
if (fd >= 0)
close(fd);
return fd >= 0 && errno != EINVAL && errno != EOPNOTSUPP;
}
static bool probe_prog_type_ifindex(enum bpf_prog_type prog_type, __u32 ifindex)
{
/* nfp returns -EINVAL on exit(0) with TC offload */
struct bpf_insn insns[2] = {
BPF_MOV64_IMM(BPF_REG_0, 2),
BPF_EXIT_INSN()
};
return probe_prog_load_ifindex(prog_type, insns, ARRAY_SIZE(insns),
NULL, 0, ifindex);
}
static void
probe_prog_type(enum bpf_prog_type prog_type, const char *prog_type_str,
bool *supported_types, const char *define_prefix, __u32 ifindex)
{
char feat_name[128], plain_desc[128], define_name[128];
const char *plain_comment = "eBPF program_type ";
size_t maxlen;
bool res;
if (ifindex) {
switch (prog_type) {
case BPF_PROG_TYPE_SCHED_CLS:
case BPF_PROG_TYPE_XDP:
break;
default:
return;
}
res = probe_prog_type_ifindex(prog_type, ifindex);
} else {
res = libbpf_probe_bpf_prog_type(prog_type, NULL) > 0;
}
#ifdef USE_LIBCAP
/* Probe may succeed even if program load fails, for unprivileged users
* check that we did not fail because of insufficient permissions
*/
if (run_as_unprivileged && errno == EPERM)
res = false;
#endif
supported_types[prog_type] |= res;
maxlen = sizeof(plain_desc) - strlen(plain_comment) - 1;
if (strlen(prog_type_str) > maxlen) {
p_info("program type name too long");
return;
}
sprintf(feat_name, "have_%s_prog_type", prog_type_str);
sprintf(define_name, "%s_prog_type", prog_type_str);
uppercase(define_name, sizeof(define_name));
sprintf(plain_desc, "%s%s", plain_comment, prog_type_str);
print_bool_feature(feat_name, plain_desc, define_name, res,
define_prefix);
}
static bool probe_map_type_ifindex(enum bpf_map_type map_type, __u32 ifindex)
{
LIBBPF_OPTS(bpf_map_create_opts, opts);
int key_size, value_size, max_entries;
int fd;
opts.map_ifindex = ifindex;
key_size = sizeof(__u32);
value_size = sizeof(__u32);
max_entries = 1;
fd = bpf_map_create(map_type, NULL, key_size, value_size, max_entries,
&opts);
if (fd >= 0)
close(fd);
return fd >= 0;
}
static void
probe_map_type(enum bpf_map_type map_type, char const *map_type_str,
const char *define_prefix, __u32 ifindex)
{
char feat_name[128], plain_desc[128], define_name[128];
const char *plain_comment = "eBPF map_type ";
size_t maxlen;
bool res;
if (ifindex) {
switch (map_type) {
case BPF_MAP_TYPE_HASH:
case BPF_MAP_TYPE_ARRAY:
break;
default:
return;
}
res = probe_map_type_ifindex(map_type, ifindex);
} else {
res = libbpf_probe_bpf_map_type(map_type, NULL) > 0;
}
/* Probe result depends on the success of map creation, no additional
* check required for unprivileged users
*/
maxlen = sizeof(plain_desc) - strlen(plain_comment) - 1;
if (strlen(map_type_str) > maxlen) {
p_info("map type name too long");
return;
}
sprintf(feat_name, "have_%s_map_type", map_type_str);
sprintf(define_name, "%s_map_type", map_type_str);
uppercase(define_name, sizeof(define_name));
sprintf(plain_desc, "%s%s", plain_comment, map_type_str);
print_bool_feature(feat_name, plain_desc, define_name, res,
define_prefix);
}
static bool
probe_helper_ifindex(enum bpf_func_id id, enum bpf_prog_type prog_type,
__u32 ifindex)
{
struct bpf_insn insns[2] = {
BPF_EMIT_CALL(id),
BPF_EXIT_INSN()
};
char buf[4096] = {};
bool res;
probe_prog_load_ifindex(prog_type, insns, ARRAY_SIZE(insns), buf,
sizeof(buf), ifindex);
res = !grep(buf, "invalid func ") && !grep(buf, "unknown func ") &&
!grep(buf, "program of this type cannot use helper ");
switch (get_vendor_id(ifindex)) {
case 0x19ee: /* Netronome specific */
res = res && !grep(buf, "not supported by FW") &&
!grep(buf, "unsupported function id");
break;
default:
break;
}
return res;
}
static bool
probe_helper_for_progtype(enum bpf_prog_type prog_type, bool supported_type,
const char *define_prefix, unsigned int id,
const char *ptype_name, __u32 ifindex)
{
bool res = false;
if (supported_type) {
if (ifindex)
res = probe_helper_ifindex(id, prog_type, ifindex);
else
res = libbpf_probe_bpf_helper(prog_type, id, NULL) > 0;
#ifdef USE_LIBCAP
/* Probe may succeed even if program load fails, for
* unprivileged users check that we did not fail because of
* insufficient permissions
*/
if (run_as_unprivileged && errno == EPERM)
res = false;
#endif
}
if (json_output) {
if (res)
jsonw_string(json_wtr, helper_name[id]);
} else if (define_prefix) {
printf("#define %sBPF__PROG_TYPE_%s__HELPER_%s %s\n",
define_prefix, ptype_name, helper_name[id],
res ? "1" : "0");
} else {
if (res)
printf("\n\t- %s", helper_name[id]);
}
return res;
}
static void
probe_helpers_for_progtype(enum bpf_prog_type prog_type,
const char *prog_type_str, bool supported_type,
const char *define_prefix, __u32 ifindex)
{
char feat_name[128];
unsigned int id;
bool probe_res = false;
if (ifindex)
/* Only test helpers for offload-able program types */
switch (prog_type) {
case BPF_PROG_TYPE_SCHED_CLS:
case BPF_PROG_TYPE_XDP:
break;
default:
return;
}
if (json_output) {
sprintf(feat_name, "%s_available_helpers", prog_type_str);
jsonw_name(json_wtr, feat_name);
jsonw_start_array(json_wtr);
} else if (!define_prefix) {
printf("eBPF helpers supported for program type %s:",
prog_type_str);
}
for (id = 1; id < ARRAY_SIZE(helper_name); id++) {
/* Skip helper functions which emit dmesg messages when not in
* the full mode.
*/
switch (id) {
case BPF_FUNC_trace_printk:
case BPF_FUNC_trace_vprintk:
case BPF_FUNC_probe_write_user:
if (!full_mode)
continue;
fallthrough;
default:
probe_res |= probe_helper_for_progtype(prog_type, supported_type,
define_prefix, id, prog_type_str,
ifindex);
}
}
if (json_output)
jsonw_end_array(json_wtr);
else if (!define_prefix) {
printf("\n");
if (!probe_res) {
if (!supported_type)
printf("\tProgram type not supported\n");
else
printf("\tCould not determine which helpers are available\n");
}
}
}
static void
probe_misc_feature(struct bpf_insn *insns, size_t len,
const char *define_prefix, __u32 ifindex,
const char *feat_name, const char *plain_name,
const char *define_name)
{
LIBBPF_OPTS(bpf_prog_load_opts, opts,
.prog_ifindex = ifindex,
);
bool res;
int fd;
errno = 0;
fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL",
insns, len, &opts);
res = fd >= 0 || !errno;
if (fd >= 0)
close(fd);
print_bool_feature(feat_name, plain_name, define_name, res,
define_prefix);
}
/*
* Probe for availability of kernel commit (5.3):
*
* c04c0d2b968a ("bpf: increase complexity limit and maximum program size")
*/
static void probe_large_insn_limit(const char *define_prefix, __u32 ifindex)
{
struct bpf_insn insns[BPF_MAXINSNS + 1];
int i;
for (i = 0; i < BPF_MAXINSNS; i++)
insns[i] = BPF_MOV64_IMM(BPF_REG_0, 1);
insns[BPF_MAXINSNS] = BPF_EXIT_INSN();
probe_misc_feature(insns, ARRAY_SIZE(insns),
define_prefix, ifindex,
"have_large_insn_limit",
"Large program size limit",
"LARGE_INSN_LIMIT");
}
/*
* Probe for bounded loop support introduced in commit 2589726d12a1
* ("bpf: introduce bounded loops").
*/
static void
probe_bounded_loops(const char *define_prefix, __u32 ifindex)
{
struct bpf_insn insns[4] = {
BPF_MOV64_IMM(BPF_REG_0, 10),
BPF_ALU64_IMM(BPF_SUB, BPF_REG_0, 1),
BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, -2),
BPF_EXIT_INSN()
};
probe_misc_feature(insns, ARRAY_SIZE(insns),
define_prefix, ifindex,
"have_bounded_loops",
"Bounded loop support",
"BOUNDED_LOOPS");
}
/*
* Probe for the v2 instruction set extension introduced in commit 92b31a9af73b
* ("bpf: add BPF_J{LT,LE,SLT,SLE} instructions").
*/
static void
probe_v2_isa_extension(const char *define_prefix, __u32 ifindex)
{
struct bpf_insn insns[4] = {
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_JMP_IMM(BPF_JLT, BPF_REG_0, 0, 1),
BPF_MOV64_IMM(BPF_REG_0, 1),
BPF_EXIT_INSN()
};
probe_misc_feature(insns, ARRAY_SIZE(insns),
define_prefix, ifindex,
"have_v2_isa_extension",
"ISA extension v2",
"V2_ISA_EXTENSION");
}
/*
* Probe for the v3 instruction set extension introduced in commit 092ed0968bb6
* ("bpf: verifier support JMP32").
*/
static void
probe_v3_isa_extension(const char *define_prefix, __u32 ifindex)
{
struct bpf_insn insns[4] = {
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_JMP32_IMM(BPF_JLT, BPF_REG_0, 0, 1),
BPF_MOV64_IMM(BPF_REG_0, 1),
BPF_EXIT_INSN()
};
probe_misc_feature(insns, ARRAY_SIZE(insns),
define_prefix, ifindex,
"have_v3_isa_extension",
"ISA extension v3",
"V3_ISA_EXTENSION");
}
static void
section_system_config(enum probe_component target, const char *define_prefix)
{
switch (target) {
case COMPONENT_KERNEL:
case COMPONENT_UNSPEC:
print_start_section("system_config",
"Scanning system configuration...",
"/*** Misc kernel config items ***/",
define_prefix);
if (!define_prefix) {
if (check_procfs()) {
probe_unprivileged_disabled();
probe_jit_enable();
probe_jit_harden();
probe_jit_kallsyms();
probe_jit_limit();
} else {
p_info("/* procfs not mounted, skipping related probes */");
}
}
probe_kernel_image_config(define_prefix);
print_end_section();
break;
default:
break;
}
}
static bool section_syscall_config(const char *define_prefix)
{
bool res;
print_start_section("syscall_config",
"Scanning system call availability...",
"/*** System call availability ***/",
define_prefix);
res = probe_bpf_syscall(define_prefix);
print_end_section();
return res;
}
static void
section_program_types(bool *supported_types, const char *define_prefix,
__u32 ifindex)
{
unsigned int prog_type = BPF_PROG_TYPE_UNSPEC;
const char *prog_type_str;
print_start_section("program_types",
"Scanning eBPF program types...",
"/*** eBPF program types ***/",
define_prefix);
while (true) {
prog_type++;
prog_type_str = libbpf_bpf_prog_type_str(prog_type);
/* libbpf will return NULL for variants unknown to it. */
if (!prog_type_str)
break;
probe_prog_type(prog_type, prog_type_str, supported_types, define_prefix,
ifindex);
}
print_end_section();
}
static void section_map_types(const char *define_prefix, __u32 ifindex)
{
unsigned int map_type = BPF_MAP_TYPE_UNSPEC;
const char *map_type_str;
print_start_section("map_types",
"Scanning eBPF map types...",
"/*** eBPF map types ***/",
define_prefix);
while (true) {
map_type++;
map_type_str = libbpf_bpf_map_type_str(map_type);
/* libbpf will return NULL for variants unknown to it. */
if (!map_type_str)
break;
probe_map_type(map_type, map_type_str, define_prefix, ifindex);
}
print_end_section();
}
static void
section_helpers(bool *supported_types, const char *define_prefix, __u32 ifindex)
{
unsigned int prog_type = BPF_PROG_TYPE_UNSPEC;
const char *prog_type_str;
print_start_section("helpers",
"Scanning eBPF helper functions...",
"/*** eBPF helper functions ***/",
define_prefix);
if (define_prefix)
printf("/*\n"
" * Use %sHAVE_PROG_TYPE_HELPER(prog_type_name, helper_name)\n"
" * to determine if <helper_name> is available for <prog_type_name>,\n"
" * e.g.\n"
" * #if %sHAVE_PROG_TYPE_HELPER(xdp, bpf_redirect)\n"
" * // do stuff with this helper\n"
" * #elif\n"
" * // use a workaround\n"
" * #endif\n"
" */\n"
"#define %sHAVE_PROG_TYPE_HELPER(prog_type, helper) \\\n"
" %sBPF__PROG_TYPE_ ## prog_type ## __HELPER_ ## helper\n",
define_prefix, define_prefix, define_prefix,
define_prefix);
while (true) {
prog_type++;
prog_type_str = libbpf_bpf_prog_type_str(prog_type);
/* libbpf will return NULL for variants unknown to it. */
if (!prog_type_str)
break;
probe_helpers_for_progtype(prog_type, prog_type_str,
supported_types[prog_type],
define_prefix,
ifindex);
}
print_end_section();
}
static void section_misc(const char *define_prefix, __u32 ifindex)
{
print_start_section("misc",
"Scanning miscellaneous eBPF features...",
"/*** eBPF misc features ***/",
define_prefix);
probe_large_insn_limit(define_prefix, ifindex);
probe_bounded_loops(define_prefix, ifindex);
probe_v2_isa_extension(define_prefix, ifindex);
probe_v3_isa_extension(define_prefix, ifindex);
print_end_section();
}
#ifdef USE_LIBCAP
#define capability(c) { c, false, #c }
#define capability_msg(a, i) a[i].set ? "" : a[i].name, a[i].set ? "" : ", "
#endif
static int handle_perms(void)
{
#ifdef USE_LIBCAP
struct {
cap_value_t cap;
bool set;
char name[14]; /* strlen("CAP_SYS_ADMIN") */
} bpf_caps[] = {
capability(CAP_SYS_ADMIN),
#ifdef CAP_BPF
capability(CAP_BPF),
capability(CAP_NET_ADMIN),
capability(CAP_PERFMON),
#endif
};
cap_value_t cap_list[ARRAY_SIZE(bpf_caps)];
unsigned int i, nb_bpf_caps = 0;
bool cap_sys_admin_only = true;
cap_flag_value_t val;
int res = -1;
cap_t caps;
caps = cap_get_proc();
if (!caps) {
p_err("failed to get capabilities for process: %s",
strerror(errno));
return -1;
}
#ifdef CAP_BPF
if (CAP_IS_SUPPORTED(CAP_BPF))
cap_sys_admin_only = false;
#endif
for (i = 0; i < ARRAY_SIZE(bpf_caps); i++) {
const char *cap_name = bpf_caps[i].name;
cap_value_t cap = bpf_caps[i].cap;
if (cap_get_flag(caps, cap, CAP_EFFECTIVE, &val)) {
p_err("bug: failed to retrieve %s status: %s", cap_name,
strerror(errno));
goto exit_free;
}
if (val == CAP_SET) {
bpf_caps[i].set = true;
cap_list[nb_bpf_caps++] = cap;
}
if (cap_sys_admin_only)
/* System does not know about CAP_BPF, meaning that
* CAP_SYS_ADMIN is the only capability required. We
* just checked it, break.
*/
break;
}
if ((run_as_unprivileged && !nb_bpf_caps) ||
(!run_as_unprivileged && nb_bpf_caps == ARRAY_SIZE(bpf_caps)) ||
(!run_as_unprivileged && cap_sys_admin_only && nb_bpf_caps)) {
/* We are all good, exit now */
res = 0;
goto exit_free;
}
if (!run_as_unprivileged) {
if (cap_sys_admin_only)
p_err("missing %s, required for full feature probing; run as root or use 'unprivileged'",
bpf_caps[0].name);
else
p_err("missing %s%s%s%s%s%s%s%srequired for full feature probing; run as root or use 'unprivileged'",
capability_msg(bpf_caps, 0),
#ifdef CAP_BPF
capability_msg(bpf_caps, 1),
capability_msg(bpf_caps, 2),
capability_msg(bpf_caps, 3)
#else
"", "", "", "", "", ""
#endif /* CAP_BPF */
);
goto exit_free;
}
/* if (run_as_unprivileged && nb_bpf_caps > 0), drop capabilities. */
if (cap_set_flag(caps, CAP_EFFECTIVE, nb_bpf_caps, cap_list,
CAP_CLEAR)) {
p_err("bug: failed to clear capabilities: %s", strerror(errno));
goto exit_free;
}
if (cap_set_proc(caps)) {
p_err("failed to drop capabilities: %s", strerror(errno));
goto exit_free;
}
res = 0;
exit_free:
if (cap_free(caps) && !res) {
p_err("failed to clear storage object for capabilities: %s",
strerror(errno));
res = -1;
}
return res;
#else
/* Detection assumes user has specific privileges.
* We do not use libcap so let's approximate, and restrict usage to
* root user only.
*/
if (geteuid()) {
p_err("full feature probing requires root privileges");
return -1;
}
return 0;
#endif /* USE_LIBCAP */
}
static int do_probe(int argc, char **argv)
{
enum probe_component target = COMPONENT_UNSPEC;
const char *define_prefix = NULL;
bool supported_types[128] = {};
__u32 ifindex = 0;
char *ifname;
set_max_rlimit();
while (argc) {
if (is_prefix(*argv, "kernel")) {
if (target != COMPONENT_UNSPEC) {
p_err("component to probe already specified");
return -1;
}
target = COMPONENT_KERNEL;
NEXT_ARG();
} else if (is_prefix(*argv, "dev")) {
NEXT_ARG();
if (target != COMPONENT_UNSPEC || ifindex) {
p_err("component to probe already specified");
return -1;
}
if (!REQ_ARGS(1))
return -1;
target = COMPONENT_DEVICE;
ifname = GET_ARG();
ifindex = if_nametoindex(ifname);
if (!ifindex) {
p_err("unrecognized netdevice '%s': %s", ifname,
strerror(errno));
return -1;
}
} else if (is_prefix(*argv, "full")) {
full_mode = true;
NEXT_ARG();
} else if (is_prefix(*argv, "macros") && !define_prefix) {
define_prefix = "";
NEXT_ARG();
} else if (is_prefix(*argv, "prefix")) {
if (!define_prefix) {
p_err("'prefix' argument can only be use after 'macros'");
return -1;
}
if (strcmp(define_prefix, "")) {
p_err("'prefix' already defined");
return -1;
}
NEXT_ARG();
if (!REQ_ARGS(1))
return -1;
define_prefix = GET_ARG();
} else if (is_prefix(*argv, "unprivileged")) {
#ifdef USE_LIBCAP
run_as_unprivileged = true;
NEXT_ARG();
#else
p_err("unprivileged run not supported, recompile bpftool with libcap");
return -1;
#endif
} else {
p_err("expected no more arguments, 'kernel', 'dev', 'macros' or 'prefix', got: '%s'?",
*argv);
return -1;
}
}
/* Full feature detection requires specific privileges.
* Let's approximate, and warn if user is not root.
*/
if (handle_perms())
return -1;
if (json_output) {
define_prefix = NULL;
jsonw_start_object(json_wtr);
}
section_system_config(target, define_prefix);
if (!section_syscall_config(define_prefix))
/* bpf() syscall unavailable, don't probe other BPF features */
goto exit_close_json;
section_program_types(supported_types, define_prefix, ifindex);
section_map_types(define_prefix, ifindex);
section_helpers(supported_types, define_prefix, ifindex);
section_misc(define_prefix, ifindex);
exit_close_json:
if (json_output)
/* End root object */
jsonw_end_object(json_wtr);
return 0;
}
static const char *get_helper_name(unsigned int id)
{
if (id >= ARRAY_SIZE(helper_name))
return NULL;
return helper_name[id];
}
static int do_list_builtins(int argc, char **argv)
{
const char *(*get_name)(unsigned int id);
unsigned int id = 0;
if (argc < 1)
usage();
if (is_prefix(*argv, "prog_types")) {
get_name = (const char *(*)(unsigned int))libbpf_bpf_prog_type_str;
} else if (is_prefix(*argv, "map_types")) {
get_name = (const char *(*)(unsigned int))libbpf_bpf_map_type_str;
} else if (is_prefix(*argv, "attach_types")) {
get_name = (const char *(*)(unsigned int))libbpf_bpf_attach_type_str;
} else if (is_prefix(*argv, "link_types")) {
get_name = (const char *(*)(unsigned int))libbpf_bpf_link_type_str;
} else if (is_prefix(*argv, "helpers")) {
get_name = get_helper_name;
} else {
p_err("expected 'prog_types', 'map_types', 'attach_types', 'link_types' or 'helpers', got: %s", *argv);
return -1;
}
if (json_output)
jsonw_start_array(json_wtr); /* root array */
while (true) {
const char *name;
name = get_name(id++);
if (!name)
break;
if (json_output)
jsonw_string(json_wtr, name);
else
printf("%s\n", name);
}
if (json_output)
jsonw_end_array(json_wtr); /* root array */
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 probe [COMPONENT] [full] [unprivileged] [macros [prefix PREFIX]]\n"
" %1$s %2$s list_builtins GROUP\n"
" %1$s %2$s help\n"
"\n"
" COMPONENT := { kernel | dev NAME }\n"
" GROUP := { prog_types | map_types | attach_types | link_types | helpers }\n"
" " HELP_SPEC_OPTIONS " }\n"
"",
bin_name, argv[-2]);
return 0;
}
static const struct cmd cmds[] = {
{ "probe", do_probe },
{ "list_builtins", do_list_builtins },
{ "help", do_help },
{ 0 }
};
int do_feature(int argc, char **argv)
{
return cmd_select(cmds, argc, argv, do_help);
}
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