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1// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
2/* Copyright (c) 2019 Netronome Systems, Inc. */
3
4#include <errno.h>
5#include <fcntl.h>
6#include <string.h>
7#include <stdlib.h>
8#include <unistd.h>
9#include <net/if.h>
10#include <sys/utsname.h>
11
12#include <linux/btf.h>
13#include <linux/filter.h>
14#include <linux/kernel.h>
15
16#include "bpf.h"
17#include "libbpf.h"
18#include "libbpf_internal.h"
19
20static int probe_prog_load(enum bpf_prog_type prog_type,
21 const struct bpf_insn *insns, size_t insns_cnt,
22 char *log_buf, size_t log_buf_sz)
23{
24 LIBBPF_OPTS(bpf_prog_load_opts, opts,
25 .log_buf = log_buf,
26 .log_size = log_buf_sz,
27 .log_level = log_buf ? 1 : 0,
28 );
29 int fd, err, exp_err = 0;
30 const char *exp_msg = NULL;
31 char buf[4096];
32
33 switch (prog_type) {
34 case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
35 opts.expected_attach_type = BPF_CGROUP_INET4_CONNECT;
36 break;
37 case BPF_PROG_TYPE_CGROUP_SOCKOPT:
38 opts.expected_attach_type = BPF_CGROUP_GETSOCKOPT;
39 break;
40 case BPF_PROG_TYPE_SK_LOOKUP:
41 opts.expected_attach_type = BPF_SK_LOOKUP;
42 break;
43 case BPF_PROG_TYPE_KPROBE:
44 opts.kern_version = get_kernel_version();
45 break;
46 case BPF_PROG_TYPE_LIRC_MODE2:
47 opts.expected_attach_type = BPF_LIRC_MODE2;
48 break;
49 case BPF_PROG_TYPE_TRACING:
50 case BPF_PROG_TYPE_LSM:
51 opts.log_buf = buf;
52 opts.log_size = sizeof(buf);
53 opts.log_level = 1;
54 if (prog_type == BPF_PROG_TYPE_TRACING)
55 opts.expected_attach_type = BPF_TRACE_FENTRY;
56 else
57 opts.expected_attach_type = BPF_MODIFY_RETURN;
58 opts.attach_btf_id = 1;
59
60 exp_err = -EINVAL;
61 exp_msg = "attach_btf_id 1 is not a function";
62 break;
63 case BPF_PROG_TYPE_EXT:
64 opts.log_buf = buf;
65 opts.log_size = sizeof(buf);
66 opts.log_level = 1;
67 opts.attach_btf_id = 1;
68
69 exp_err = -EINVAL;
70 exp_msg = "Cannot replace kernel functions";
71 break;
72 case BPF_PROG_TYPE_SYSCALL:
73 opts.prog_flags = BPF_F_SLEEPABLE;
74 break;
75 case BPF_PROG_TYPE_STRUCT_OPS:
76 exp_err = -524; /* -ENOTSUPP */
77 break;
78 case BPF_PROG_TYPE_UNSPEC:
79 case BPF_PROG_TYPE_SOCKET_FILTER:
80 case BPF_PROG_TYPE_SCHED_CLS:
81 case BPF_PROG_TYPE_SCHED_ACT:
82 case BPF_PROG_TYPE_TRACEPOINT:
83 case BPF_PROG_TYPE_XDP:
84 case BPF_PROG_TYPE_PERF_EVENT:
85 case BPF_PROG_TYPE_CGROUP_SKB:
86 case BPF_PROG_TYPE_CGROUP_SOCK:
87 case BPF_PROG_TYPE_LWT_IN:
88 case BPF_PROG_TYPE_LWT_OUT:
89 case BPF_PROG_TYPE_LWT_XMIT:
90 case BPF_PROG_TYPE_SOCK_OPS:
91 case BPF_PROG_TYPE_SK_SKB:
92 case BPF_PROG_TYPE_CGROUP_DEVICE:
93 case BPF_PROG_TYPE_SK_MSG:
94 case BPF_PROG_TYPE_RAW_TRACEPOINT:
95 case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
96 case BPF_PROG_TYPE_LWT_SEG6LOCAL:
97 case BPF_PROG_TYPE_SK_REUSEPORT:
98 case BPF_PROG_TYPE_FLOW_DISSECTOR:
99 case BPF_PROG_TYPE_CGROUP_SYSCTL:
100 break;
101 default:
102 return -EOPNOTSUPP;
103 }
104
105 fd = bpf_prog_load(prog_type, NULL, "GPL", insns, insns_cnt, &opts);
106 err = -errno;
107 if (fd >= 0)
108 close(fd);
109 if (exp_err) {
110 if (fd >= 0 || err != exp_err)
111 return 0;
112 if (exp_msg && !strstr(buf, exp_msg))
113 return 0;
114 return 1;
115 }
116 return fd >= 0 ? 1 : 0;
117}
118
119int libbpf_probe_bpf_prog_type(enum bpf_prog_type prog_type, const void *opts)
120{
121 struct bpf_insn insns[] = {
122 BPF_MOV64_IMM(BPF_REG_0, 0),
123 BPF_EXIT_INSN()
124 };
125 const size_t insn_cnt = ARRAY_SIZE(insns);
126 int ret;
127
128 if (opts)
129 return libbpf_err(-EINVAL);
130
131 ret = probe_prog_load(prog_type, insns, insn_cnt, NULL, 0);
132 return libbpf_err(ret);
133}
134
135int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
136 const char *str_sec, size_t str_len)
137{
138 struct btf_header hdr = {
139 .magic = BTF_MAGIC,
140 .version = BTF_VERSION,
141 .hdr_len = sizeof(struct btf_header),
142 .type_len = types_len,
143 .str_off = types_len,
144 .str_len = str_len,
145 };
146 int btf_fd, btf_len;
147 __u8 *raw_btf;
148
149 btf_len = hdr.hdr_len + hdr.type_len + hdr.str_len;
150 raw_btf = malloc(btf_len);
151 if (!raw_btf)
152 return -ENOMEM;
153
154 memcpy(raw_btf, &hdr, sizeof(hdr));
155 memcpy(raw_btf + hdr.hdr_len, raw_types, hdr.type_len);
156 memcpy(raw_btf + hdr.hdr_len + hdr.type_len, str_sec, hdr.str_len);
157
158 btf_fd = bpf_btf_load(raw_btf, btf_len, NULL);
159
160 free(raw_btf);
161 return btf_fd;
162}
163
164static int load_local_storage_btf(void)
165{
166 const char strs[] = "\0bpf_spin_lock\0val\0cnt\0l";
167 /* struct bpf_spin_lock {
168 * int val;
169 * };
170 * struct val {
171 * int cnt;
172 * struct bpf_spin_lock l;
173 * };
174 */
175 __u32 types[] = {
176 /* int */
177 BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
178 /* struct bpf_spin_lock */ /* [2] */
179 BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 1), 4),
180 BTF_MEMBER_ENC(15, 1, 0), /* int val; */
181 /* struct val */ /* [3] */
182 BTF_TYPE_ENC(15, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 8),
183 BTF_MEMBER_ENC(19, 1, 0), /* int cnt; */
184 BTF_MEMBER_ENC(23, 2, 32),/* struct bpf_spin_lock l; */
185 };
186
187 return libbpf__load_raw_btf((char *)types, sizeof(types),
188 strs, sizeof(strs));
189}
190
191static int probe_map_create(enum bpf_map_type map_type)
192{
193 LIBBPF_OPTS(bpf_map_create_opts, opts);
194 int key_size, value_size, max_entries;
195 __u32 btf_key_type_id = 0, btf_value_type_id = 0;
196 int fd = -1, btf_fd = -1, fd_inner = -1, exp_err = 0, err = 0;
197
198 key_size = sizeof(__u32);
199 value_size = sizeof(__u32);
200 max_entries = 1;
201
202 switch (map_type) {
203 case BPF_MAP_TYPE_STACK_TRACE:
204 value_size = sizeof(__u64);
205 break;
206 case BPF_MAP_TYPE_LPM_TRIE:
207 key_size = sizeof(__u64);
208 value_size = sizeof(__u64);
209 opts.map_flags = BPF_F_NO_PREALLOC;
210 break;
211 case BPF_MAP_TYPE_CGROUP_STORAGE:
212 case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE:
213 key_size = sizeof(struct bpf_cgroup_storage_key);
214 value_size = sizeof(__u64);
215 max_entries = 0;
216 break;
217 case BPF_MAP_TYPE_QUEUE:
218 case BPF_MAP_TYPE_STACK:
219 key_size = 0;
220 break;
221 case BPF_MAP_TYPE_SK_STORAGE:
222 case BPF_MAP_TYPE_INODE_STORAGE:
223 case BPF_MAP_TYPE_TASK_STORAGE:
224 case BPF_MAP_TYPE_CGRP_STORAGE:
225 btf_key_type_id = 1;
226 btf_value_type_id = 3;
227 value_size = 8;
228 max_entries = 0;
229 opts.map_flags = BPF_F_NO_PREALLOC;
230 btf_fd = load_local_storage_btf();
231 if (btf_fd < 0)
232 return btf_fd;
233 break;
234 case BPF_MAP_TYPE_RINGBUF:
235 case BPF_MAP_TYPE_USER_RINGBUF:
236 key_size = 0;
237 value_size = 0;
238 max_entries = sysconf(_SC_PAGE_SIZE);
239 break;
240 case BPF_MAP_TYPE_STRUCT_OPS:
241 /* we'll get -ENOTSUPP for invalid BTF type ID for struct_ops */
242 opts.btf_vmlinux_value_type_id = 1;
243 exp_err = -524; /* -ENOTSUPP */
244 break;
245 case BPF_MAP_TYPE_BLOOM_FILTER:
246 key_size = 0;
247 max_entries = 1;
248 break;
249 case BPF_MAP_TYPE_HASH:
250 case BPF_MAP_TYPE_ARRAY:
251 case BPF_MAP_TYPE_PROG_ARRAY:
252 case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
253 case BPF_MAP_TYPE_PERCPU_HASH:
254 case BPF_MAP_TYPE_PERCPU_ARRAY:
255 case BPF_MAP_TYPE_CGROUP_ARRAY:
256 case BPF_MAP_TYPE_LRU_HASH:
257 case BPF_MAP_TYPE_LRU_PERCPU_HASH:
258 case BPF_MAP_TYPE_ARRAY_OF_MAPS:
259 case BPF_MAP_TYPE_HASH_OF_MAPS:
260 case BPF_MAP_TYPE_DEVMAP:
261 case BPF_MAP_TYPE_DEVMAP_HASH:
262 case BPF_MAP_TYPE_SOCKMAP:
263 case BPF_MAP_TYPE_CPUMAP:
264 case BPF_MAP_TYPE_XSKMAP:
265 case BPF_MAP_TYPE_SOCKHASH:
266 case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
267 break;
268 case BPF_MAP_TYPE_UNSPEC:
269 default:
270 return -EOPNOTSUPP;
271 }
272
273 if (map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
274 map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
275 fd_inner = bpf_map_create(BPF_MAP_TYPE_HASH, NULL,
276 sizeof(__u32), sizeof(__u32), 1, NULL);
277 if (fd_inner < 0)
278 goto cleanup;
279
280 opts.inner_map_fd = fd_inner;
281 }
282
283 if (btf_fd >= 0) {
284 opts.btf_fd = btf_fd;
285 opts.btf_key_type_id = btf_key_type_id;
286 opts.btf_value_type_id = btf_value_type_id;
287 }
288
289 fd = bpf_map_create(map_type, NULL, key_size, value_size, max_entries, &opts);
290 err = -errno;
291
292cleanup:
293 if (fd >= 0)
294 close(fd);
295 if (fd_inner >= 0)
296 close(fd_inner);
297 if (btf_fd >= 0)
298 close(btf_fd);
299
300 if (exp_err)
301 return fd < 0 && err == exp_err ? 1 : 0;
302 else
303 return fd >= 0 ? 1 : 0;
304}
305
306int libbpf_probe_bpf_map_type(enum bpf_map_type map_type, const void *opts)
307{
308 int ret;
309
310 if (opts)
311 return libbpf_err(-EINVAL);
312
313 ret = probe_map_create(map_type);
314 return libbpf_err(ret);
315}
316
317int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type, enum bpf_func_id helper_id,
318 const void *opts)
319{
320 struct bpf_insn insns[] = {
321 BPF_EMIT_CALL((__u32)helper_id),
322 BPF_EXIT_INSN(),
323 };
324 const size_t insn_cnt = ARRAY_SIZE(insns);
325 char buf[4096];
326 int ret;
327
328 if (opts)
329 return libbpf_err(-EINVAL);
330
331 /* we can't successfully load all prog types to check for BPF helper
332 * support, so bail out with -EOPNOTSUPP error
333 */
334 switch (prog_type) {
335 case BPF_PROG_TYPE_TRACING:
336 case BPF_PROG_TYPE_EXT:
337 case BPF_PROG_TYPE_LSM:
338 case BPF_PROG_TYPE_STRUCT_OPS:
339 return -EOPNOTSUPP;
340 default:
341 break;
342 }
343
344 buf[0] = '\0';
345 ret = probe_prog_load(prog_type, insns, insn_cnt, buf, sizeof(buf));
346 if (ret < 0)
347 return libbpf_err(ret);
348
349 /* If BPF verifier doesn't recognize BPF helper ID (enum bpf_func_id)
350 * at all, it will emit something like "invalid func unknown#181".
351 * If BPF verifier recognizes BPF helper but it's not supported for
352 * given BPF program type, it will emit "unknown func bpf_sys_bpf#166".
353 * In both cases, provided combination of BPF program type and BPF
354 * helper is not supported by the kernel.
355 * In all other cases, probe_prog_load() above will either succeed (e.g.,
356 * because BPF helper happens to accept no input arguments or it
357 * accepts one input argument and initial PTR_TO_CTX is fine for
358 * that), or we'll get some more specific BPF verifier error about
359 * some unsatisfied conditions.
360 */
361 if (ret == 0 && (strstr(buf, "invalid func ") || strstr(buf, "unknown func ")))
362 return 0;
363 return 1; /* assume supported */
364}