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 | */ |
31 | static __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 | */ |
63 | static __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: &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 | |
103 | static 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, license: "GPL" , insns, insn_cnt: insns_cnt, opts: &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 | |
205 | int 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(ret: -EINVAL); |
216 | |
217 | ret = probe_prog_load(prog_type, insns, insns_cnt: insn_cnt, NULL, log_buf_sz: 0); |
218 | return libbpf_err(ret); |
219 | } |
220 | |
221 | int libbpf__load_raw_btf(const char *raw_types, size_t types_len, |
222 | const char *str_sec, size_t str_len, |
223 | int token_fd) |
224 | { |
225 | struct btf_header hdr = { |
226 | .magic = BTF_MAGIC, |
227 | .version = BTF_VERSION, |
228 | .hdr_len = sizeof(struct btf_header), |
229 | .type_len = types_len, |
230 | .str_off = types_len, |
231 | .str_len = str_len, |
232 | }; |
233 | LIBBPF_OPTS(bpf_btf_load_opts, opts, |
234 | .token_fd = token_fd, |
235 | .btf_flags = token_fd ? BPF_F_TOKEN_FD : 0, |
236 | ); |
237 | int btf_fd, btf_len; |
238 | __u8 *raw_btf; |
239 | |
240 | btf_len = hdr.hdr_len + hdr.type_len + hdr.str_len; |
241 | raw_btf = malloc(btf_len); |
242 | if (!raw_btf) |
243 | return -ENOMEM; |
244 | |
245 | memcpy(raw_btf, &hdr, sizeof(hdr)); |
246 | memcpy(raw_btf + hdr.hdr_len, raw_types, hdr.type_len); |
247 | memcpy(raw_btf + hdr.hdr_len + hdr.type_len, str_sec, hdr.str_len); |
248 | |
249 | btf_fd = bpf_btf_load(btf_data: raw_btf, btf_size: btf_len, opts: &opts); |
250 | |
251 | free(raw_btf); |
252 | return btf_fd; |
253 | } |
254 | |
255 | static int load_local_storage_btf(void) |
256 | { |
257 | const char strs[] = "\0bpf_spin_lock\0val\0cnt\0l" ; |
258 | /* struct bpf_spin_lock { |
259 | * int val; |
260 | * }; |
261 | * struct val { |
262 | * int cnt; |
263 | * struct bpf_spin_lock l; |
264 | * }; |
265 | */ |
266 | __u32 types[] = { |
267 | /* int */ |
268 | BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */ |
269 | /* struct bpf_spin_lock */ /* [2] */ |
270 | BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 1), 4), |
271 | BTF_MEMBER_ENC(15, 1, 0), /* int val; */ |
272 | /* struct val */ /* [3] */ |
273 | BTF_TYPE_ENC(15, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 8), |
274 | BTF_MEMBER_ENC(19, 1, 0), /* int cnt; */ |
275 | BTF_MEMBER_ENC(23, 2, 32),/* struct bpf_spin_lock l; */ |
276 | }; |
277 | |
278 | return libbpf__load_raw_btf(raw_types: (char *)types, types_len: sizeof(types), |
279 | str_sec: strs, str_len: sizeof(strs), token_fd: 0); |
280 | } |
281 | |
282 | static int probe_map_create(enum bpf_map_type map_type) |
283 | { |
284 | LIBBPF_OPTS(bpf_map_create_opts, opts); |
285 | int key_size, value_size, max_entries; |
286 | __u32 btf_key_type_id = 0, btf_value_type_id = 0; |
287 | int fd = -1, btf_fd = -1, fd_inner = -1, exp_err = 0, err = 0; |
288 | |
289 | key_size = sizeof(__u32); |
290 | value_size = sizeof(__u32); |
291 | max_entries = 1; |
292 | |
293 | switch (map_type) { |
294 | case BPF_MAP_TYPE_STACK_TRACE: |
295 | value_size = sizeof(__u64); |
296 | break; |
297 | case BPF_MAP_TYPE_LPM_TRIE: |
298 | key_size = sizeof(__u64); |
299 | value_size = sizeof(__u64); |
300 | opts.map_flags = BPF_F_NO_PREALLOC; |
301 | break; |
302 | case BPF_MAP_TYPE_CGROUP_STORAGE: |
303 | case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE: |
304 | key_size = sizeof(struct bpf_cgroup_storage_key); |
305 | value_size = sizeof(__u64); |
306 | max_entries = 0; |
307 | break; |
308 | case BPF_MAP_TYPE_QUEUE: |
309 | case BPF_MAP_TYPE_STACK: |
310 | key_size = 0; |
311 | break; |
312 | case BPF_MAP_TYPE_SK_STORAGE: |
313 | case BPF_MAP_TYPE_INODE_STORAGE: |
314 | case BPF_MAP_TYPE_TASK_STORAGE: |
315 | case BPF_MAP_TYPE_CGRP_STORAGE: |
316 | btf_key_type_id = 1; |
317 | btf_value_type_id = 3; |
318 | value_size = 8; |
319 | max_entries = 0; |
320 | opts.map_flags = BPF_F_NO_PREALLOC; |
321 | btf_fd = load_local_storage_btf(); |
322 | if (btf_fd < 0) |
323 | return btf_fd; |
324 | break; |
325 | case BPF_MAP_TYPE_RINGBUF: |
326 | case BPF_MAP_TYPE_USER_RINGBUF: |
327 | key_size = 0; |
328 | value_size = 0; |
329 | max_entries = sysconf(_SC_PAGE_SIZE); |
330 | break; |
331 | case BPF_MAP_TYPE_STRUCT_OPS: |
332 | /* we'll get -ENOTSUPP for invalid BTF type ID for struct_ops */ |
333 | opts.btf_vmlinux_value_type_id = 1; |
334 | opts.value_type_btf_obj_fd = -1; |
335 | exp_err = -524; /* -ENOTSUPP */ |
336 | break; |
337 | case BPF_MAP_TYPE_BLOOM_FILTER: |
338 | key_size = 0; |
339 | max_entries = 1; |
340 | break; |
341 | case BPF_MAP_TYPE_ARENA: |
342 | key_size = 0; |
343 | value_size = 0; |
344 | max_entries = 1; /* one page */ |
345 | opts.map_extra = 0; /* can mmap() at any address */ |
346 | opts.map_flags = BPF_F_MMAPABLE; |
347 | break; |
348 | case BPF_MAP_TYPE_HASH: |
349 | case BPF_MAP_TYPE_ARRAY: |
350 | case BPF_MAP_TYPE_PROG_ARRAY: |
351 | case BPF_MAP_TYPE_PERF_EVENT_ARRAY: |
352 | case BPF_MAP_TYPE_PERCPU_HASH: |
353 | case BPF_MAP_TYPE_PERCPU_ARRAY: |
354 | case BPF_MAP_TYPE_CGROUP_ARRAY: |
355 | case BPF_MAP_TYPE_LRU_HASH: |
356 | case BPF_MAP_TYPE_LRU_PERCPU_HASH: |
357 | case BPF_MAP_TYPE_ARRAY_OF_MAPS: |
358 | case BPF_MAP_TYPE_HASH_OF_MAPS: |
359 | case BPF_MAP_TYPE_DEVMAP: |
360 | case BPF_MAP_TYPE_DEVMAP_HASH: |
361 | case BPF_MAP_TYPE_SOCKMAP: |
362 | case BPF_MAP_TYPE_CPUMAP: |
363 | case BPF_MAP_TYPE_XSKMAP: |
364 | case BPF_MAP_TYPE_SOCKHASH: |
365 | case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY: |
366 | break; |
367 | case BPF_MAP_TYPE_UNSPEC: |
368 | default: |
369 | return -EOPNOTSUPP; |
370 | } |
371 | |
372 | if (map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS || |
373 | map_type == BPF_MAP_TYPE_HASH_OF_MAPS) { |
374 | fd_inner = bpf_map_create(map_type: BPF_MAP_TYPE_HASH, NULL, |
375 | key_size: sizeof(__u32), value_size: sizeof(__u32), max_entries: 1, NULL); |
376 | if (fd_inner < 0) |
377 | goto cleanup; |
378 | |
379 | opts.inner_map_fd = fd_inner; |
380 | } |
381 | |
382 | if (btf_fd >= 0) { |
383 | opts.btf_fd = btf_fd; |
384 | opts.btf_key_type_id = btf_key_type_id; |
385 | opts.btf_value_type_id = btf_value_type_id; |
386 | } |
387 | |
388 | fd = bpf_map_create(map_type, NULL, key_size, value_size, max_entries, opts: &opts); |
389 | err = -errno; |
390 | |
391 | cleanup: |
392 | if (fd >= 0) |
393 | close(fd); |
394 | if (fd_inner >= 0) |
395 | close(fd_inner); |
396 | if (btf_fd >= 0) |
397 | close(btf_fd); |
398 | |
399 | if (exp_err) |
400 | return fd < 0 && err == exp_err ? 1 : 0; |
401 | else |
402 | return fd >= 0 ? 1 : 0; |
403 | } |
404 | |
405 | int libbpf_probe_bpf_map_type(enum bpf_map_type map_type, const void *opts) |
406 | { |
407 | int ret; |
408 | |
409 | if (opts) |
410 | return libbpf_err(ret: -EINVAL); |
411 | |
412 | ret = probe_map_create(map_type); |
413 | return libbpf_err(ret); |
414 | } |
415 | |
416 | int libbpf_probe_bpf_helper(enum bpf_prog_type prog_type, enum bpf_func_id helper_id, |
417 | const void *opts) |
418 | { |
419 | struct bpf_insn insns[] = { |
420 | BPF_EMIT_CALL((__u32)helper_id), |
421 | BPF_EXIT_INSN(), |
422 | }; |
423 | const size_t insn_cnt = ARRAY_SIZE(insns); |
424 | char buf[4096]; |
425 | int ret; |
426 | |
427 | if (opts) |
428 | return libbpf_err(ret: -EINVAL); |
429 | |
430 | /* we can't successfully load all prog types to check for BPF helper |
431 | * support, so bail out with -EOPNOTSUPP error |
432 | */ |
433 | switch (prog_type) { |
434 | case BPF_PROG_TYPE_TRACING: |
435 | case BPF_PROG_TYPE_EXT: |
436 | case BPF_PROG_TYPE_LSM: |
437 | case BPF_PROG_TYPE_STRUCT_OPS: |
438 | return -EOPNOTSUPP; |
439 | default: |
440 | break; |
441 | } |
442 | |
443 | buf[0] = '\0'; |
444 | ret = probe_prog_load(prog_type, insns, insns_cnt: insn_cnt, log_buf: buf, log_buf_sz: sizeof(buf)); |
445 | if (ret < 0) |
446 | return libbpf_err(ret); |
447 | |
448 | /* If BPF verifier doesn't recognize BPF helper ID (enum bpf_func_id) |
449 | * at all, it will emit something like "invalid func unknown#181". |
450 | * If BPF verifier recognizes BPF helper but it's not supported for |
451 | * given BPF program type, it will emit "unknown func bpf_sys_bpf#166". |
452 | * In both cases, provided combination of BPF program type and BPF |
453 | * helper is not supported by the kernel. |
454 | * In all other cases, probe_prog_load() above will either succeed (e.g., |
455 | * because BPF helper happens to accept no input arguments or it |
456 | * accepts one input argument and initial PTR_TO_CTX is fine for |
457 | * that), or we'll get some more specific BPF verifier error about |
458 | * some unsatisfied conditions. |
459 | */ |
460 | if (ret == 0 && (strstr(buf, "invalid func " ) || strstr(buf, "unknown func " ))) |
461 | return 0; |
462 | return 1; /* assume supported */ |
463 | } |
464 | |