Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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#include <linux/version.h>
16
17#include "bpf.h"
18#include "libbpf.h"
19#include "libbpf_internal.h"
20
21/* On Ubuntu LINUX_VERSION_CODE doesn't correspond to info.release,
22 * but Ubuntu provides /proc/version_signature file, as described at
23 * https://ubuntu.com/kernel, with an example contents below, which we
24 * can use to get a proper LINUX_VERSION_CODE.
25 *
26 * Ubuntu 5.4.0-12.15-generic 5.4.8
27 *
28 * In the above, 5.4.8 is what kernel is actually expecting, while
29 * uname() call will return 5.4.0 in info.release.
30 */
31static __u32 get_ubuntu_kernel_version(void)
32{
33 const char *ubuntu_kver_file = "/proc/version_signature";
34 __u32 major, minor, patch;
35 int ret;
36 FILE *f;
37
38 if (faccessat(AT_FDCWD, ubuntu_kver_file, R_OK, AT_EACCESS) != 0)
39 return 0;
40
41 f = fopen(ubuntu_kver_file, "re");
42 if (!f)
43 return 0;
44
45 ret = fscanf(f, "%*s %*s %u.%u.%u\n", &major, &minor, &patch);
46 fclose(f);
47 if (ret != 3)
48 return 0;
49
50 return KERNEL_VERSION(major, minor, patch);
51}
52
53/* On Debian LINUX_VERSION_CODE doesn't correspond to info.release.
54 * Instead, it is provided in info.version. An example content of
55 * Debian 10 looks like the below.
56 *
57 * utsname::release 4.19.0-22-amd64
58 * utsname::version #1 SMP Debian 4.19.260-1 (2022-09-29)
59 *
60 * In the above, 4.19.260 is what kernel is actually expecting, while
61 * uname() call will return 4.19.0 in info.release.
62 */
63static __u32 get_debian_kernel_version(struct utsname *info)
64{
65 __u32 major, minor, patch;
66 char *p;
67
68 p = strstr(info->version, "Debian ");
69 if (!p) {
70 /* This is not a Debian kernel. */
71 return 0;
72 }
73
74 if (sscanf(p, "Debian %u.%u.%u", &major, &minor, &patch) != 3)
75 return 0;
76
77 return KERNEL_VERSION(major, minor, patch);
78}
79
80__u32 get_kernel_version(void)
81{
82 __u32 major, minor, patch, version;
83 struct utsname info;
84
85 /* Check if this is an Ubuntu kernel. */
86 version = get_ubuntu_kernel_version();
87 if (version != 0)
88 return version;
89
90 uname(&info);
91
92 /* Check if this is a Debian kernel. */
93 version = get_debian_kernel_version(&info);
94 if (version != 0)
95 return version;
96
97 if (sscanf(info.release, "%u.%u.%u", &major, &minor, &patch) != 3)
98 return 0;
99
100 return KERNEL_VERSION(major, minor, patch);
101}
102
103static int probe_prog_load(enum bpf_prog_type prog_type,
104 const struct bpf_insn *insns, size_t insns_cnt,
105 char *log_buf, size_t log_buf_sz)
106{
107 LIBBPF_OPTS(bpf_prog_load_opts, opts,
108 .log_buf = log_buf,
109 .log_size = log_buf_sz,
110 .log_level = log_buf ? 1 : 0,
111 );
112 int fd, err, exp_err = 0;
113 const char *exp_msg = NULL;
114 char buf[4096];
115
116 switch (prog_type) {
117 case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
118 opts.expected_attach_type = BPF_CGROUP_INET4_CONNECT;
119 break;
120 case BPF_PROG_TYPE_CGROUP_SOCKOPT:
121 opts.expected_attach_type = BPF_CGROUP_GETSOCKOPT;
122 break;
123 case BPF_PROG_TYPE_SK_LOOKUP:
124 opts.expected_attach_type = BPF_SK_LOOKUP;
125 break;
126 case BPF_PROG_TYPE_KPROBE:
127 opts.kern_version = get_kernel_version();
128 break;
129 case BPF_PROG_TYPE_LIRC_MODE2:
130 opts.expected_attach_type = BPF_LIRC_MODE2;
131 break;
132 case BPF_PROG_TYPE_TRACING:
133 case BPF_PROG_TYPE_LSM:
134 opts.log_buf = buf;
135 opts.log_size = sizeof(buf);
136 opts.log_level = 1;
137 if (prog_type == BPF_PROG_TYPE_TRACING)
138 opts.expected_attach_type = BPF_TRACE_FENTRY;
139 else
140 opts.expected_attach_type = BPF_MODIFY_RETURN;
141 opts.attach_btf_id = 1;
142
143 exp_err = -EINVAL;
144 exp_msg = "attach_btf_id 1 is not a function";
145 break;
146 case BPF_PROG_TYPE_EXT:
147 opts.log_buf = buf;
148 opts.log_size = sizeof(buf);
149 opts.log_level = 1;
150 opts.attach_btf_id = 1;
151
152 exp_err = -EINVAL;
153 exp_msg = "Cannot replace kernel functions";
154 break;
155 case BPF_PROG_TYPE_SYSCALL:
156 opts.prog_flags = BPF_F_SLEEPABLE;
157 break;
158 case BPF_PROG_TYPE_STRUCT_OPS:
159 exp_err = -524; /* -ENOTSUPP */
160 break;
161 case BPF_PROG_TYPE_UNSPEC:
162 case BPF_PROG_TYPE_SOCKET_FILTER:
163 case BPF_PROG_TYPE_SCHED_CLS:
164 case BPF_PROG_TYPE_SCHED_ACT:
165 case BPF_PROG_TYPE_TRACEPOINT:
166 case BPF_PROG_TYPE_XDP:
167 case BPF_PROG_TYPE_PERF_EVENT:
168 case BPF_PROG_TYPE_CGROUP_SKB:
169 case BPF_PROG_TYPE_CGROUP_SOCK:
170 case BPF_PROG_TYPE_LWT_IN:
171 case BPF_PROG_TYPE_LWT_OUT:
172 case BPF_PROG_TYPE_LWT_XMIT:
173 case BPF_PROG_TYPE_SOCK_OPS:
174 case BPF_PROG_TYPE_SK_SKB:
175 case BPF_PROG_TYPE_CGROUP_DEVICE:
176 case BPF_PROG_TYPE_SK_MSG:
177 case BPF_PROG_TYPE_RAW_TRACEPOINT:
178 case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
179 case BPF_PROG_TYPE_LWT_SEG6LOCAL:
180 case BPF_PROG_TYPE_SK_REUSEPORT:
181 case BPF_PROG_TYPE_FLOW_DISSECTOR:
182 case BPF_PROG_TYPE_CGROUP_SYSCTL:
183 break;
184 case BPF_PROG_TYPE_NETFILTER:
185 opts.expected_attach_type = BPF_NETFILTER;
186 break;
187 default:
188 return -EOPNOTSUPP;
189 }
190
191 fd = bpf_prog_load(prog_type, NULL, "GPL", insns, insns_cnt, &opts);
192 err = -errno;
193 if (fd >= 0)
194 close(fd);
195 if (exp_err) {
196 if (fd >= 0 || err != exp_err)
197 return 0;
198 if (exp_msg && !strstr(buf, exp_msg))
199 return 0;
200 return 1;
201 }
202 return fd >= 0 ? 1 : 0;
203}
204
205int libbpf_probe_bpf_prog_type(enum bpf_prog_type prog_type, const void *opts)
206{
207 struct bpf_insn insns[] = {
208 BPF_MOV64_IMM(BPF_REG_0, 0),
209 BPF_EXIT_INSN()
210 };
211 const size_t insn_cnt = ARRAY_SIZE(insns);
212 int ret;
213
214 if (opts)
215 return libbpf_err(-EINVAL);
216
217 ret = probe_prog_load(prog_type, insns, insn_cnt, NULL, 0);
218 return libbpf_err(ret);
219}
220
221int libbpf__load_raw_btf_hdr(const struct btf_header *hdr, const char *raw_types,
222 const char *str_sec, const char *layout_sec,
223 int token_fd)
224{
225 LIBBPF_OPTS(bpf_btf_load_opts, opts,
226 .token_fd = token_fd,
227 .btf_flags = token_fd ? BPF_F_TOKEN_FD : 0,
228 );
229 int btf_fd, btf_len;
230 __u8 *raw_btf;
231
232 btf_len = hdr->hdr_len + hdr->type_off + hdr->type_len + hdr->str_len + hdr->layout_len;
233 raw_btf = malloc(btf_len);
234 if (!raw_btf)
235 return -ENOMEM;
236
237 memcpy(raw_btf, hdr, sizeof(*hdr));
238 memcpy(raw_btf + hdr->hdr_len + hdr->type_off, raw_types, hdr->type_len);
239 memcpy(raw_btf + hdr->hdr_len + hdr->str_off, str_sec, hdr->str_len);
240 if (layout_sec)
241 memcpy(raw_btf + hdr->hdr_len + hdr->layout_off, layout_sec, hdr->layout_len);
242
243 btf_fd = bpf_btf_load(raw_btf, btf_len, &opts);
244
245 free(raw_btf);
246 return btf_fd;
247}
248
249int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
250 const char *str_sec, size_t str_len,
251 int token_fd)
252{
253 struct btf_header hdr = {
254 .magic = BTF_MAGIC,
255 .version = BTF_VERSION,
256 .hdr_len = sizeof(struct btf_header),
257 .type_len = types_len,
258 .str_off = types_len,
259 .str_len = str_len,
260 };
261
262 return libbpf__load_raw_btf_hdr(&hdr, raw_types, str_sec, NULL, token_fd);
263}
264
265static int load_local_storage_btf(void)
266{
267 const char strs[] = "\0bpf_spin_lock\0val\0cnt\0l";
268 /* struct bpf_spin_lock {
269 * int val;
270 * };
271 * struct val {
272 * int cnt;
273 * struct bpf_spin_lock l;
274 * };
275 */
276 __u32 types[] = {
277 /* int */
278 BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
279 /* struct bpf_spin_lock */ /* [2] */
280 BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 1), 4),
281 BTF_MEMBER_ENC(15, 1, 0), /* int val; */
282 /* struct val */ /* [3] */
283 BTF_TYPE_ENC(15, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 8),
284 BTF_MEMBER_ENC(19, 1, 0), /* int cnt; */
285 BTF_MEMBER_ENC(23, 2, 32),/* struct bpf_spin_lock l; */
286 };
287
288 return libbpf__load_raw_btf((char *)types, sizeof(types),
289 strs, sizeof(strs), 0);
290}
291
292static int probe_map_create(enum bpf_map_type map_type)
293{
294 LIBBPF_OPTS(bpf_map_create_opts, opts);
295 int key_size, value_size, max_entries;
296 __u32 btf_key_type_id = 0, btf_value_type_id = 0;
297 int fd = -1, btf_fd = -1, fd_inner = -1, exp_err = 0, err = 0;
298
299 key_size = sizeof(__u32);
300 value_size = sizeof(__u32);
301 max_entries = 1;
302
303 switch (map_type) {
304 case BPF_MAP_TYPE_STACK_TRACE:
305 value_size = sizeof(__u64);
306 break;
307 case BPF_MAP_TYPE_LPM_TRIE:
308 key_size = sizeof(__u64);
309 value_size = sizeof(__u64);
310 opts.map_flags = BPF_F_NO_PREALLOC;
311 break;
312 case BPF_MAP_TYPE_CGROUP_STORAGE:
313 case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE:
314 key_size = sizeof(struct bpf_cgroup_storage_key);
315 value_size = sizeof(__u64);
316 max_entries = 0;
317 break;
318 case BPF_MAP_TYPE_QUEUE:
319 case BPF_MAP_TYPE_STACK:
320 key_size = 0;
321 break;
322 case BPF_MAP_TYPE_SK_STORAGE:
323 case BPF_MAP_TYPE_INODE_STORAGE:
324 case BPF_MAP_TYPE_TASK_STORAGE:
325 case BPF_MAP_TYPE_CGRP_STORAGE:
326 btf_key_type_id = 1;
327 btf_value_type_id = 3;
328 value_size = 8;
329 max_entries = 0;
330 opts.map_flags = BPF_F_NO_PREALLOC;
331 btf_fd = load_local_storage_btf();
332 if (btf_fd < 0)
333 return btf_fd;
334 break;
335 case BPF_MAP_TYPE_RINGBUF:
336 case BPF_MAP_TYPE_USER_RINGBUF:
337 key_size = 0;
338 value_size = 0;
339 max_entries = sysconf(_SC_PAGE_SIZE);
340 break;
341 case BPF_MAP_TYPE_STRUCT_OPS:
342 /* we'll get -ENOTSUPP for invalid BTF type ID for struct_ops */
343 opts.btf_vmlinux_value_type_id = 1;
344 opts.value_type_btf_obj_fd = -1;
345 exp_err = -524; /* -ENOTSUPP */
346 break;
347 case BPF_MAP_TYPE_BLOOM_FILTER:
348 key_size = 0;
349 max_entries = 1;
350 break;
351 case BPF_MAP_TYPE_ARENA:
352 key_size = 0;
353 value_size = 0;
354 max_entries = 1; /* one page */
355 opts.map_extra = 0; /* can mmap() at any address */
356 opts.map_flags = BPF_F_MMAPABLE;
357 break;
358 case BPF_MAP_TYPE_HASH:
359 case BPF_MAP_TYPE_ARRAY:
360 case BPF_MAP_TYPE_PROG_ARRAY:
361 case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
362 case BPF_MAP_TYPE_PERCPU_HASH:
363 case BPF_MAP_TYPE_PERCPU_ARRAY:
364 case BPF_MAP_TYPE_CGROUP_ARRAY:
365 case BPF_MAP_TYPE_LRU_HASH:
366 case BPF_MAP_TYPE_LRU_PERCPU_HASH:
367 case BPF_MAP_TYPE_ARRAY_OF_MAPS:
368 case BPF_MAP_TYPE_HASH_OF_MAPS:
369 case BPF_MAP_TYPE_DEVMAP:
370 case BPF_MAP_TYPE_DEVMAP_HASH:
371 case BPF_MAP_TYPE_SOCKMAP:
372 case BPF_MAP_TYPE_CPUMAP:
373 case BPF_MAP_TYPE_XSKMAP:
374 case BPF_MAP_TYPE_SOCKHASH:
375 case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
376 break;
377 case BPF_MAP_TYPE_INSN_ARRAY:
378 key_size = sizeof(__u32);
379 value_size = sizeof(struct bpf_insn_array_value);
380 break;
381 case BPF_MAP_TYPE_UNSPEC:
382 default:
383 return -EOPNOTSUPP;
384 }
385
386 if (map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
387 map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
388 fd_inner = bpf_map_create(BPF_MAP_TYPE_HASH, NULL,
389 sizeof(__u32), sizeof(__u32), 1, NULL);
390 if (fd_inner < 0)
391 goto cleanup;
392
393 opts.inner_map_fd = fd_inner;
394 }
395
396 if (btf_fd >= 0) {
397 opts.btf_fd = btf_fd;
398 opts.btf_key_type_id = btf_key_type_id;
399 opts.btf_value_type_id = btf_value_type_id;
400 }
401
402 fd = bpf_map_create(map_type, NULL, key_size, value_size, max_entries, &opts);
403 err = -errno;
404
405cleanup:
406 if (fd >= 0)
407 close(fd);
408 if (fd_inner >= 0)
409 close(fd_inner);
410 if (btf_fd >= 0)
411 close(btf_fd);
412
413 if (exp_err)
414 return fd < 0 && err == exp_err ? 1 : 0;
415 else
416 return fd >= 0 ? 1 : 0;
417}
418
419int libbpf_probe_bpf_map_type(enum bpf_map_type map_type, const void *opts)
420{
421 int ret;
422
423 if (opts)
424 return libbpf_err(-EINVAL);
425
426 ret = probe_map_create(map_type);
427 return libbpf_err(ret);
428}
429
430int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type, enum bpf_func_id helper_id,
431 const void *opts)
432{
433 struct bpf_insn insns[] = {
434 BPF_EMIT_CALL((__u32)helper_id),
435 BPF_EXIT_INSN(),
436 };
437 const size_t insn_cnt = ARRAY_SIZE(insns);
438 char buf[4096];
439 int ret;
440
441 if (opts)
442 return libbpf_err(-EINVAL);
443
444 /* we can't successfully load all prog types to check for BPF helper
445 * support, so bail out with -EOPNOTSUPP error
446 */
447 switch (prog_type) {
448 case BPF_PROG_TYPE_TRACING:
449 case BPF_PROG_TYPE_EXT:
450 case BPF_PROG_TYPE_LSM:
451 case BPF_PROG_TYPE_STRUCT_OPS:
452 return -EOPNOTSUPP;
453 default:
454 break;
455 }
456
457 buf[0] = '\0';
458 ret = probe_prog_load(prog_type, insns, insn_cnt, buf, sizeof(buf));
459 if (ret < 0)
460 return libbpf_err(ret);
461
462 /* If BPF verifier doesn't recognize BPF helper ID (enum bpf_func_id)
463 * at all, it will emit something like "invalid func unknown#181".
464 * If BPF verifier recognizes BPF helper but it's not supported for
465 * given BPF program type, it will emit "unknown func bpf_sys_bpf#166"
466 * or "program of this type cannot use helper bpf_sys_bpf#166".
467 * In both cases, provided combination of BPF program type and BPF
468 * helper is not supported by the kernel.
469 * In all other cases, probe_prog_load() above will either succeed (e.g.,
470 * because BPF helper happens to accept no input arguments or it
471 * accepts one input argument and initial PTR_TO_CTX is fine for
472 * that), or we'll get some more specific BPF verifier error about
473 * some unsatisfied conditions.
474 */
475 if (ret == 0 && (strstr(buf, "invalid func ") || strstr(buf, "unknown func ") ||
476 strstr(buf, "program of this type cannot use helper ")))
477 return 0;
478 return 1; /* assume supported */
479}