364 lines
9.2 KiB
C
364 lines
9.2 KiB
C
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// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
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/* Copyright (c) 2019 Netronome Systems, Inc. */
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#include <errno.h>
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#include <fcntl.h>
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#include <string.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <net/if.h>
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#include <sys/utsname.h>
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#include <linux/btf.h>
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#include <linux/filter.h>
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#include <linux/kernel.h>
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#include "bpf.h"
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#include "libbpf.h"
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#include "libbpf_internal.h"
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static int probe_prog_load(enum bpf_prog_type prog_type,
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const struct bpf_insn *insns, size_t insns_cnt,
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char *log_buf, size_t log_buf_sz)
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{
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LIBBPF_OPTS(bpf_prog_load_opts, opts,
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.log_buf = log_buf,
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.log_size = log_buf_sz,
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.log_level = log_buf ? 1 : 0,
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);
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int fd, err, exp_err = 0;
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const char *exp_msg = NULL;
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char buf[4096];
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switch (prog_type) {
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case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
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opts.expected_attach_type = BPF_CGROUP_INET4_CONNECT;
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break;
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case BPF_PROG_TYPE_CGROUP_SOCKOPT:
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opts.expected_attach_type = BPF_CGROUP_GETSOCKOPT;
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break;
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case BPF_PROG_TYPE_SK_LOOKUP:
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opts.expected_attach_type = BPF_SK_LOOKUP;
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break;
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case BPF_PROG_TYPE_KPROBE:
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opts.kern_version = get_kernel_version();
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break;
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case BPF_PROG_TYPE_LIRC_MODE2:
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opts.expected_attach_type = BPF_LIRC_MODE2;
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break;
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case BPF_PROG_TYPE_TRACING:
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case BPF_PROG_TYPE_LSM:
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opts.log_buf = buf;
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opts.log_size = sizeof(buf);
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opts.log_level = 1;
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if (prog_type == BPF_PROG_TYPE_TRACING)
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opts.expected_attach_type = BPF_TRACE_FENTRY;
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else
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opts.expected_attach_type = BPF_MODIFY_RETURN;
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opts.attach_btf_id = 1;
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exp_err = -EINVAL;
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exp_msg = "attach_btf_id 1 is not a function";
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break;
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case BPF_PROG_TYPE_EXT:
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opts.log_buf = buf;
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opts.log_size = sizeof(buf);
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opts.log_level = 1;
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opts.attach_btf_id = 1;
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exp_err = -EINVAL;
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exp_msg = "Cannot replace kernel functions";
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break;
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case BPF_PROG_TYPE_SYSCALL:
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opts.prog_flags = BPF_F_SLEEPABLE;
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break;
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case BPF_PROG_TYPE_STRUCT_OPS:
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exp_err = -524; /* -ENOTSUPP */
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break;
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case BPF_PROG_TYPE_UNSPEC:
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case BPF_PROG_TYPE_SOCKET_FILTER:
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case BPF_PROG_TYPE_SCHED_CLS:
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case BPF_PROG_TYPE_SCHED_ACT:
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case BPF_PROG_TYPE_TRACEPOINT:
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case BPF_PROG_TYPE_XDP:
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case BPF_PROG_TYPE_PERF_EVENT:
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case BPF_PROG_TYPE_CGROUP_SKB:
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case BPF_PROG_TYPE_CGROUP_SOCK:
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case BPF_PROG_TYPE_LWT_IN:
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case BPF_PROG_TYPE_LWT_OUT:
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case BPF_PROG_TYPE_LWT_XMIT:
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case BPF_PROG_TYPE_SOCK_OPS:
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case BPF_PROG_TYPE_SK_SKB:
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case BPF_PROG_TYPE_CGROUP_DEVICE:
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case BPF_PROG_TYPE_SK_MSG:
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case BPF_PROG_TYPE_RAW_TRACEPOINT:
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case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
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case BPF_PROG_TYPE_LWT_SEG6LOCAL:
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case BPF_PROG_TYPE_SK_REUSEPORT:
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case BPF_PROG_TYPE_FLOW_DISSECTOR:
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case BPF_PROG_TYPE_CGROUP_SYSCTL:
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break;
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default:
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return -EOPNOTSUPP;
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}
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fd = bpf_prog_load(prog_type, NULL, "GPL", insns, insns_cnt, &opts);
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err = -errno;
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if (fd >= 0)
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close(fd);
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if (exp_err) {
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if (fd >= 0 || err != exp_err)
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return 0;
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if (exp_msg && !strstr(buf, exp_msg))
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return 0;
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return 1;
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}
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return fd >= 0 ? 1 : 0;
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}
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int libbpf_probe_bpf_prog_type(enum bpf_prog_type prog_type, const void *opts)
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{
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struct bpf_insn insns[] = {
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BPF_MOV64_IMM(BPF_REG_0, 0),
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BPF_EXIT_INSN()
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};
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const size_t insn_cnt = ARRAY_SIZE(insns);
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int ret;
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if (opts)
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return libbpf_err(-EINVAL);
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ret = probe_prog_load(prog_type, insns, insn_cnt, NULL, 0);
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return libbpf_err(ret);
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}
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int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
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const char *str_sec, size_t str_len)
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{
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struct btf_header hdr = {
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.magic = BTF_MAGIC,
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.version = BTF_VERSION,
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.hdr_len = sizeof(struct btf_header),
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.type_len = types_len,
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.str_off = types_len,
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.str_len = str_len,
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};
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int btf_fd, btf_len;
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__u8 *raw_btf;
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btf_len = hdr.hdr_len + hdr.type_len + hdr.str_len;
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raw_btf = malloc(btf_len);
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if (!raw_btf)
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return -ENOMEM;
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memcpy(raw_btf, &hdr, sizeof(hdr));
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memcpy(raw_btf + hdr.hdr_len, raw_types, hdr.type_len);
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memcpy(raw_btf + hdr.hdr_len + hdr.type_len, str_sec, hdr.str_len);
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btf_fd = bpf_btf_load(raw_btf, btf_len, NULL);
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free(raw_btf);
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return btf_fd;
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}
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static int load_local_storage_btf(void)
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{
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const char strs[] = "\0bpf_spin_lock\0val\0cnt\0l";
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/* struct bpf_spin_lock {
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* int val;
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* };
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* struct val {
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* int cnt;
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* struct bpf_spin_lock l;
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* };
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*/
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__u32 types[] = {
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/* int */
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BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
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/* struct bpf_spin_lock */ /* [2] */
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BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 1), 4),
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BTF_MEMBER_ENC(15, 1, 0), /* int val; */
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/* struct val */ /* [3] */
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BTF_TYPE_ENC(15, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 8),
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BTF_MEMBER_ENC(19, 1, 0), /* int cnt; */
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BTF_MEMBER_ENC(23, 2, 32),/* struct bpf_spin_lock l; */
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};
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return libbpf__load_raw_btf((char *)types, sizeof(types),
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strs, sizeof(strs));
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}
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static int probe_map_create(enum bpf_map_type map_type)
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{
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LIBBPF_OPTS(bpf_map_create_opts, opts);
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int key_size, value_size, max_entries;
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__u32 btf_key_type_id = 0, btf_value_type_id = 0;
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int fd = -1, btf_fd = -1, fd_inner = -1, exp_err = 0, err = 0;
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key_size = sizeof(__u32);
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value_size = sizeof(__u32);
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max_entries = 1;
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switch (map_type) {
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case BPF_MAP_TYPE_STACK_TRACE:
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value_size = sizeof(__u64);
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break;
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case BPF_MAP_TYPE_LPM_TRIE:
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key_size = sizeof(__u64);
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value_size = sizeof(__u64);
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opts.map_flags = BPF_F_NO_PREALLOC;
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break;
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case BPF_MAP_TYPE_CGROUP_STORAGE:
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case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE:
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key_size = sizeof(struct bpf_cgroup_storage_key);
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value_size = sizeof(__u64);
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max_entries = 0;
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break;
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case BPF_MAP_TYPE_QUEUE:
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case BPF_MAP_TYPE_STACK:
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key_size = 0;
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break;
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case BPF_MAP_TYPE_SK_STORAGE:
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case BPF_MAP_TYPE_INODE_STORAGE:
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case BPF_MAP_TYPE_TASK_STORAGE:
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btf_key_type_id = 1;
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btf_value_type_id = 3;
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value_size = 8;
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max_entries = 0;
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opts.map_flags = BPF_F_NO_PREALLOC;
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btf_fd = load_local_storage_btf();
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if (btf_fd < 0)
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return btf_fd;
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break;
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case BPF_MAP_TYPE_RINGBUF:
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case BPF_MAP_TYPE_USER_RINGBUF:
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key_size = 0;
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value_size = 0;
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max_entries = sysconf(_SC_PAGE_SIZE);
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break;
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case BPF_MAP_TYPE_STRUCT_OPS:
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/* we'll get -ENOTSUPP for invalid BTF type ID for struct_ops */
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opts.btf_vmlinux_value_type_id = 1;
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exp_err = -524; /* -ENOTSUPP */
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break;
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case BPF_MAP_TYPE_BLOOM_FILTER:
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key_size = 0;
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max_entries = 1;
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break;
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case BPF_MAP_TYPE_HASH:
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case BPF_MAP_TYPE_ARRAY:
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case BPF_MAP_TYPE_PROG_ARRAY:
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case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
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case BPF_MAP_TYPE_PERCPU_HASH:
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case BPF_MAP_TYPE_PERCPU_ARRAY:
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case BPF_MAP_TYPE_CGROUP_ARRAY:
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case BPF_MAP_TYPE_LRU_HASH:
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case BPF_MAP_TYPE_LRU_PERCPU_HASH:
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case BPF_MAP_TYPE_ARRAY_OF_MAPS:
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case BPF_MAP_TYPE_HASH_OF_MAPS:
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case BPF_MAP_TYPE_DEVMAP:
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case BPF_MAP_TYPE_DEVMAP_HASH:
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case BPF_MAP_TYPE_SOCKMAP:
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case BPF_MAP_TYPE_CPUMAP:
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case BPF_MAP_TYPE_XSKMAP:
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case BPF_MAP_TYPE_SOCKHASH:
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case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
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break;
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case BPF_MAP_TYPE_UNSPEC:
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default:
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return -EOPNOTSUPP;
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}
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if (map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
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map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
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fd_inner = bpf_map_create(BPF_MAP_TYPE_HASH, NULL,
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sizeof(__u32), sizeof(__u32), 1, NULL);
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if (fd_inner < 0)
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goto cleanup;
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opts.inner_map_fd = fd_inner;
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}
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if (btf_fd >= 0) {
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opts.btf_fd = btf_fd;
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opts.btf_key_type_id = btf_key_type_id;
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opts.btf_value_type_id = btf_value_type_id;
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}
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fd = bpf_map_create(map_type, NULL, key_size, value_size, max_entries, &opts);
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err = -errno;
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cleanup:
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if (fd >= 0)
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close(fd);
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if (fd_inner >= 0)
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close(fd_inner);
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if (btf_fd >= 0)
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close(btf_fd);
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if (exp_err)
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return fd < 0 && err == exp_err ? 1 : 0;
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else
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return fd >= 0 ? 1 : 0;
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}
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int libbpf_probe_bpf_map_type(enum bpf_map_type map_type, const void *opts)
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{
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int ret;
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if (opts)
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return libbpf_err(-EINVAL);
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ret = probe_map_create(map_type);
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return libbpf_err(ret);
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}
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int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type, enum bpf_func_id helper_id,
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const void *opts)
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{
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struct bpf_insn insns[] = {
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BPF_EMIT_CALL((__u32)helper_id),
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BPF_EXIT_INSN(),
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};
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const size_t insn_cnt = ARRAY_SIZE(insns);
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char buf[4096];
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int ret;
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if (opts)
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return libbpf_err(-EINVAL);
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/* we can't successfully load all prog types to check for BPF helper
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* support, so bail out with -EOPNOTSUPP error
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*/
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switch (prog_type) {
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case BPF_PROG_TYPE_TRACING:
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case BPF_PROG_TYPE_EXT:
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case BPF_PROG_TYPE_LSM:
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case BPF_PROG_TYPE_STRUCT_OPS:
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return -EOPNOTSUPP;
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default:
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break;
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}
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buf[0] = '\0';
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ret = probe_prog_load(prog_type, insns, insn_cnt, buf, sizeof(buf));
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if (ret < 0)
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return libbpf_err(ret);
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/* If BPF verifier doesn't recognize BPF helper ID (enum bpf_func_id)
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* 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".
|
||
|
|
* 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 ")))
|
||
|
|
return 0;
|
||
|
|
return 1; /* assume supported */
|
||
|
|
}
|