diff options
Diffstat (limited to 'tools/bpf/bpftool/feature.c')
| -rw-r--r-- | tools/bpf/bpftool/feature.c | 1019 |
1 files changed, 1019 insertions, 0 deletions
diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c new file mode 100644 index 000000000..5f0b13977 --- /dev/null +++ b/tools/bpf/bpftool/feature.c @@ -0,0 +1,1019 @@ +// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +/* Copyright (c) 2019 Netronome Systems, Inc. */ + +#include <ctype.h> +#include <errno.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 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 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 ouptut */ + + 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\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 ouptut */ + + 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 ouptut */ + + 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 ouptut */ + + 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 ouptut */ + + 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", }, + + /* 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", }, + /* bpfilter back-end for iptables */ + { "CONFIG_BPFILTER", }, + /* bpftilter module with "user mode helper" */ + { "CONFIG_BPFILTER_UMH", }, + + /* 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); + } + } + +end_parse: + if (file) + gzclose(file); + + 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]); + } +} + +static bool probe_bpf_syscall(const char *define_prefix) +{ + bool res; + + bpf_load_program(BPF_PROG_TYPE_UNSPEC, NULL, 0, NULL, 0, NULL, 0); + res = (errno != ENOSYS); + + print_bool_feature("have_bpf_syscall", + "bpf() syscall", + "BPF_SYSCALL", + res, define_prefix); + + return res; +} + +static void +probe_prog_type(enum bpf_prog_type prog_type, 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) + /* Only test offload-able program types */ + switch (prog_type) { + case BPF_PROG_TYPE_SCHED_CLS: + case BPF_PROG_TYPE_XDP: + break; + default: + return; + } + + res = bpf_probe_prog_type(prog_type, ifindex); +#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; + + if (!prog_type_name[prog_type]) { + p_info("program type name not found (type %d)", prog_type); + return; + } + maxlen = sizeof(plain_desc) - strlen(plain_comment) - 1; + if (strlen(prog_type_name[prog_type]) > maxlen) { + p_info("program type name too long"); + return; + } + + sprintf(feat_name, "have_%s_prog_type", prog_type_name[prog_type]); + sprintf(define_name, "%s_prog_type", prog_type_name[prog_type]); + uppercase(define_name, sizeof(define_name)); + sprintf(plain_desc, "%s%s", plain_comment, prog_type_name[prog_type]); + print_bool_feature(feat_name, plain_desc, define_name, res, + define_prefix); +} + +static void +probe_map_type(enum bpf_map_type map_type, 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; + + res = bpf_probe_map_type(map_type, ifindex); + + /* Probe result depends on the success of map creation, no additional + * check required for unprivileged users + */ + + if (!map_type_name[map_type]) { + p_info("map type name not found (type %d)", map_type); + return; + } + maxlen = sizeof(plain_desc) - strlen(plain_comment) - 1; + if (strlen(map_type_name[map_type]) > maxlen) { + p_info("map type name too long"); + return; + } + + sprintf(feat_name, "have_%s_map_type", map_type_name[map_type]); + sprintf(define_name, "%s_map_type", map_type_name[map_type]); + uppercase(define_name, sizeof(define_name)); + sprintf(plain_desc, "%s%s", plain_comment, map_type_name[map_type]); + print_bool_feature(feat_name, plain_desc, define_name, res, + define_prefix); +} + +static void +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) { + res = bpf_probe_helper(id, prog_type, ifindex); +#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]); + } +} + +static void +probe_helpers_for_progtype(enum bpf_prog_type prog_type, bool supported_type, + const char *define_prefix, __u32 ifindex) +{ + const char *ptype_name = prog_type_name[prog_type]; + char feat_name[128]; + unsigned int id; + + 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", ptype_name); + jsonw_name(json_wtr, feat_name); + jsonw_start_array(json_wtr); + } else if (!define_prefix) { + printf("eBPF helpers supported for program type %s:", + ptype_name); + } + + 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_probe_write_user: + if (!full_mode) + continue; + /* fallthrough */ + default: + probe_helper_for_progtype(prog_type, supported_type, + define_prefix, id, ptype_name, + ifindex); + } + } + + if (json_output) + jsonw_end_array(json_wtr); + else if (!define_prefix) + printf("\n"); +} + +static void +probe_large_insn_limit(const char *define_prefix, __u32 ifindex) +{ + bool res; + + res = bpf_probe_large_insn_limit(ifindex); + print_bool_feature("have_large_insn_limit", + "Large program size limit", + "LARGE_INSN_LIMIT", + res, define_prefix); +} + +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 i; + + print_start_section("program_types", + "Scanning eBPF program types...", + "/*** eBPF program types ***/", + define_prefix); + + for (i = BPF_PROG_TYPE_UNSPEC + 1; i < prog_type_name_size; i++) + probe_prog_type(i, supported_types, define_prefix, ifindex); + + print_end_section(); +} + +static void section_map_types(const char *define_prefix, __u32 ifindex) +{ + unsigned int i; + + print_start_section("map_types", + "Scanning eBPF map types...", + "/*** eBPF map types ***/", + define_prefix); + + for (i = BPF_MAP_TYPE_UNSPEC + 1; i < map_type_name_size; i++) + probe_map_type(i, define_prefix, ifindex); + + print_end_section(); +} + +static void +section_helpers(bool *supported_types, const char *define_prefix, __u32 ifindex) +{ + unsigned int i; + + 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); + for (i = BPF_PROG_TYPE_UNSPEC + 1; i < prog_type_name_size; i++) + probe_helpers_for_progtype(i, supported_types[i], 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); + 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 libpcap 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 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 help\n" + "\n" + " COMPONENT := { kernel | dev NAME }\n" + "", + bin_name, argv[-2]); + + return 0; +} + +static const struct cmd cmds[] = { + { "probe", do_probe }, + { "help", do_help }, + { 0 } +}; + +int do_feature(int argc, char **argv) +{ + return cmd_select(cmds, argc, argv, do_help); +} |