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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#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(const char *raw_types, size_t types_len,
222 const char *str_sec, size_t str_len)
223{
224 struct btf_header hdr = {
225 .magic = BTF_MAGIC,
226 .version = BTF_VERSION,
227 .hdr_len = sizeof(struct btf_header),
228 .type_len = types_len,
229 .str_off = types_len,
230 .str_len = str_len,
231 };
232 int btf_fd, btf_len;
233 __u8 *raw_btf;
234
235 btf_len = hdr.hdr_len + hdr.type_len + hdr.str_len;
236 raw_btf = malloc(btf_len);
237 if (!raw_btf)
238 return -ENOMEM;
239
240 memcpy(raw_btf, &hdr, sizeof(hdr));
241 memcpy(raw_btf + hdr.hdr_len, raw_types, hdr.type_len);
242 memcpy(raw_btf + hdr.hdr_len + hdr.type_len, str_sec, hdr.str_len);
243
244 btf_fd = bpf_btf_load(raw_btf, btf_len, NULL);
245
246 free(raw_btf);
247 return btf_fd;
248}
249
250static int load_local_storage_btf(void)
251{
252 const char strs[] = "\0bpf_spin_lock\0val\0cnt\0l";
253 /* struct bpf_spin_lock {
254 * int val;
255 * };
256 * struct val {
257 * int cnt;
258 * struct bpf_spin_lock l;
259 * };
260 */
261 __u32 types[] = {
262 /* int */
263 BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
264 /* struct bpf_spin_lock */ /* [2] */
265 BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 1), 4),
266 BTF_MEMBER_ENC(15, 1, 0), /* int val; */
267 /* struct val */ /* [3] */
268 BTF_TYPE_ENC(15, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 8),
269 BTF_MEMBER_ENC(19, 1, 0), /* int cnt; */
270 BTF_MEMBER_ENC(23, 2, 32),/* struct bpf_spin_lock l; */
271 };
272
273 return libbpf__load_raw_btf((char *)types, sizeof(types),
274 strs, sizeof(strs));
275}
276
277static int probe_map_create(enum bpf_map_type map_type)
278{
279 LIBBPF_OPTS(bpf_map_create_opts, opts);
280 int key_size, value_size, max_entries;
281 __u32 btf_key_type_id = 0, btf_value_type_id = 0;
282 int fd = -1, btf_fd = -1, fd_inner = -1, exp_err = 0, err = 0;
283
284 key_size = sizeof(__u32);
285 value_size = sizeof(__u32);
286 max_entries = 1;
287
288 switch (map_type) {
289 case BPF_MAP_TYPE_STACK_TRACE:
290 value_size = sizeof(__u64);
291 break;
292 case BPF_MAP_TYPE_LPM_TRIE:
293 key_size = sizeof(__u64);
294 value_size = sizeof(__u64);
295 opts.map_flags = BPF_F_NO_PREALLOC;
296 break;
297 case BPF_MAP_TYPE_CGROUP_STORAGE:
298 case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE:
299 key_size = sizeof(struct bpf_cgroup_storage_key);
300 value_size = sizeof(__u64);
301 max_entries = 0;
302 break;
303 case BPF_MAP_TYPE_QUEUE:
304 case BPF_MAP_TYPE_STACK:
305 key_size = 0;
306 break;
307 case BPF_MAP_TYPE_SK_STORAGE:
308 case BPF_MAP_TYPE_INODE_STORAGE:
309 case BPF_MAP_TYPE_TASK_STORAGE:
310 case BPF_MAP_TYPE_CGRP_STORAGE:
311 btf_key_type_id = 1;
312 btf_value_type_id = 3;
313 value_size = 8;
314 max_entries = 0;
315 opts.map_flags = BPF_F_NO_PREALLOC;
316 btf_fd = load_local_storage_btf();
317 if (btf_fd < 0)
318 return btf_fd;
319 break;
320 case BPF_MAP_TYPE_RINGBUF:
321 case BPF_MAP_TYPE_USER_RINGBUF:
322 key_size = 0;
323 value_size = 0;
324 max_entries = sysconf(_SC_PAGE_SIZE);
325 break;
326 case BPF_MAP_TYPE_STRUCT_OPS:
327 /* we'll get -ENOTSUPP for invalid BTF type ID for struct_ops */
328 opts.btf_vmlinux_value_type_id = 1;
329 exp_err = -524; /* -ENOTSUPP */
330 break;
331 case BPF_MAP_TYPE_BLOOM_FILTER:
332 key_size = 0;
333 max_entries = 1;
334 break;
335 case BPF_MAP_TYPE_HASH:
336 case BPF_MAP_TYPE_ARRAY:
337 case BPF_MAP_TYPE_PROG_ARRAY:
338 case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
339 case BPF_MAP_TYPE_PERCPU_HASH:
340 case BPF_MAP_TYPE_PERCPU_ARRAY:
341 case BPF_MAP_TYPE_CGROUP_ARRAY:
342 case BPF_MAP_TYPE_LRU_HASH:
343 case BPF_MAP_TYPE_LRU_PERCPU_HASH:
344 case BPF_MAP_TYPE_ARRAY_OF_MAPS:
345 case BPF_MAP_TYPE_HASH_OF_MAPS:
346 case BPF_MAP_TYPE_DEVMAP:
347 case BPF_MAP_TYPE_DEVMAP_HASH:
348 case BPF_MAP_TYPE_SOCKMAP:
349 case BPF_MAP_TYPE_CPUMAP:
350 case BPF_MAP_TYPE_XSKMAP:
351 case BPF_MAP_TYPE_SOCKHASH:
352 case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
353 break;
354 case BPF_MAP_TYPE_UNSPEC:
355 default:
356 return -EOPNOTSUPP;
357 }
358
359 if (map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
360 map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
361 fd_inner = bpf_map_create(BPF_MAP_TYPE_HASH, NULL,
362 sizeof(__u32), sizeof(__u32), 1, NULL);
363 if (fd_inner < 0)
364 goto cleanup;
365
366 opts.inner_map_fd = fd_inner;
367 }
368
369 if (btf_fd >= 0) {
370 opts.btf_fd = btf_fd;
371 opts.btf_key_type_id = btf_key_type_id;
372 opts.btf_value_type_id = btf_value_type_id;
373 }
374
375 fd = bpf_map_create(map_type, NULL, key_size, value_size, max_entries, &opts);
376 err = -errno;
377
378cleanup:
379 if (fd >= 0)
380 close(fd);
381 if (fd_inner >= 0)
382 close(fd_inner);
383 if (btf_fd >= 0)
384 close(btf_fd);
385
386 if (exp_err)
387 return fd < 0 && err == exp_err ? 1 : 0;
388 else
389 return fd >= 0 ? 1 : 0;
390}
391
392int libbpf_probe_bpf_map_type(enum bpf_map_type map_type, const void *opts)
393{
394 int ret;
395
396 if (opts)
397 return libbpf_err(-EINVAL);
398
399 ret = probe_map_create(map_type);
400 return libbpf_err(ret);
401}
402
403int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type, enum bpf_func_id helper_id,
404 const void *opts)
405{
406 struct bpf_insn insns[] = {
407 BPF_EMIT_CALL((__u32)helper_id),
408 BPF_EXIT_INSN(),
409 };
410 const size_t insn_cnt = ARRAY_SIZE(insns);
411 char buf[4096];
412 int ret;
413
414 if (opts)
415 return libbpf_err(-EINVAL);
416
417 /* we can't successfully load all prog types to check for BPF helper
418 * support, so bail out with -EOPNOTSUPP error
419 */
420 switch (prog_type) {
421 case BPF_PROG_TYPE_TRACING:
422 case BPF_PROG_TYPE_EXT:
423 case BPF_PROG_TYPE_LSM:
424 case BPF_PROG_TYPE_STRUCT_OPS:
425 return -EOPNOTSUPP;
426 default:
427 break;
428 }
429
430 buf[0] = '\0';
431 ret = probe_prog_load(prog_type, insns, insn_cnt, buf, sizeof(buf));
432 if (ret < 0)
433 return libbpf_err(ret);
434
435 /* If BPF verifier doesn't recognize BPF helper ID (enum bpf_func_id)
436 * at all, it will emit something like "invalid func unknown#181".
437 * If BPF verifier recognizes BPF helper but it's not supported for
438 * given BPF program type, it will emit "unknown func bpf_sys_bpf#166".
439 * In both cases, provided combination of BPF program type and BPF
440 * helper is not supported by the kernel.
441 * In all other cases, probe_prog_load() above will either succeed (e.g.,
442 * because BPF helper happens to accept no input arguments or it
443 * accepts one input argument and initial PTR_TO_CTX is fine for
444 * that), or we'll get some more specific BPF verifier error about
445 * some unsatisfied conditions.
446 */
447 if (ret == 0 && (strstr(buf, "invalid func ") || strstr(buf, "unknown func ")))
448 return 0;
449 return 1; /* assume supported */
450}