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1#include <stdio.h>
2#include <sys/types.h>
3#include <sys/stat.h>
4#include <fcntl.h>
5#include <libelf.h>
6#include <gelf.h>
7#include <errno.h>
8#include <unistd.h>
9#include <string.h>
10#include <stdbool.h>
11#include <stdlib.h>
12#include <linux/bpf.h>
13#include <linux/filter.h>
14#include <linux/perf_event.h>
15#include <sys/syscall.h>
16#include <sys/ioctl.h>
17#include <sys/mman.h>
18#include <poll.h>
19#include <ctype.h>
20#include "libbpf.h"
21#include "bpf_helpers.h"
22#include "bpf_load.h"
23
24#define DEBUGFS "/sys/kernel/debug/tracing/"
25
26static char license[128];
27static int kern_version;
28static bool processed_sec[128];
29int map_fd[MAX_MAPS];
30int prog_fd[MAX_PROGS];
31int event_fd[MAX_PROGS];
32int prog_cnt;
33int prog_array_fd = -1;
34
35static int populate_prog_array(const char *event, int prog_fd)
36{
37 int ind = atoi(event), err;
38
39 err = bpf_update_elem(prog_array_fd, &ind, &prog_fd, BPF_ANY);
40 if (err < 0) {
41 printf("failed to store prog_fd in prog_array\n");
42 return -1;
43 }
44 return 0;
45}
46
47static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
48{
49 bool is_socket = strncmp(event, "socket", 6) == 0;
50 bool is_kprobe = strncmp(event, "kprobe/", 7) == 0;
51 bool is_kretprobe = strncmp(event, "kretprobe/", 10) == 0;
52 enum bpf_prog_type prog_type;
53 char buf[256];
54 int fd, efd, err, id;
55 struct perf_event_attr attr = {};
56
57 attr.type = PERF_TYPE_TRACEPOINT;
58 attr.sample_type = PERF_SAMPLE_RAW;
59 attr.sample_period = 1;
60 attr.wakeup_events = 1;
61
62 if (is_socket) {
63 prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
64 } else if (is_kprobe || is_kretprobe) {
65 prog_type = BPF_PROG_TYPE_KPROBE;
66 } else {
67 printf("Unknown event '%s'\n", event);
68 return -1;
69 }
70
71 fd = bpf_prog_load(prog_type, prog, size, license, kern_version);
72 if (fd < 0) {
73 printf("bpf_prog_load() err=%d\n%s", errno, bpf_log_buf);
74 return -1;
75 }
76
77 prog_fd[prog_cnt++] = fd;
78
79 if (is_socket) {
80 event += 6;
81 if (*event != '/')
82 return 0;
83 event++;
84 if (!isdigit(*event)) {
85 printf("invalid prog number\n");
86 return -1;
87 }
88 return populate_prog_array(event, fd);
89 }
90
91 if (is_kprobe || is_kretprobe) {
92 if (is_kprobe)
93 event += 7;
94 else
95 event += 10;
96
97 if (*event == 0) {
98 printf("event name cannot be empty\n");
99 return -1;
100 }
101
102 if (isdigit(*event))
103 return populate_prog_array(event, fd);
104
105 snprintf(buf, sizeof(buf),
106 "echo '%c:%s %s' >> /sys/kernel/debug/tracing/kprobe_events",
107 is_kprobe ? 'p' : 'r', event, event);
108 err = system(buf);
109 if (err < 0) {
110 printf("failed to create kprobe '%s' error '%s'\n",
111 event, strerror(errno));
112 return -1;
113 }
114 }
115
116 strcpy(buf, DEBUGFS);
117 strcat(buf, "events/kprobes/");
118 strcat(buf, event);
119 strcat(buf, "/id");
120
121 efd = open(buf, O_RDONLY, 0);
122 if (efd < 0) {
123 printf("failed to open event %s\n", event);
124 return -1;
125 }
126
127 err = read(efd, buf, sizeof(buf));
128 if (err < 0 || err >= sizeof(buf)) {
129 printf("read from '%s' failed '%s'\n", event, strerror(errno));
130 return -1;
131 }
132
133 close(efd);
134
135 buf[err] = 0;
136 id = atoi(buf);
137 attr.config = id;
138
139 efd = perf_event_open(&attr, -1/*pid*/, 0/*cpu*/, -1/*group_fd*/, 0);
140 if (efd < 0) {
141 printf("event %d fd %d err %s\n", id, efd, strerror(errno));
142 return -1;
143 }
144 event_fd[prog_cnt - 1] = efd;
145 ioctl(efd, PERF_EVENT_IOC_ENABLE, 0);
146 ioctl(efd, PERF_EVENT_IOC_SET_BPF, fd);
147
148 return 0;
149}
150
151static int load_maps(struct bpf_map_def *maps, int len)
152{
153 int i;
154
155 for (i = 0; i < len / sizeof(struct bpf_map_def); i++) {
156
157 map_fd[i] = bpf_create_map(maps[i].type,
158 maps[i].key_size,
159 maps[i].value_size,
160 maps[i].max_entries,
161 maps[i].map_flags);
162 if (map_fd[i] < 0) {
163 printf("failed to create a map: %d %s\n",
164 errno, strerror(errno));
165 return 1;
166 }
167
168 if (maps[i].type == BPF_MAP_TYPE_PROG_ARRAY)
169 prog_array_fd = map_fd[i];
170 }
171 return 0;
172}
173
174static int get_sec(Elf *elf, int i, GElf_Ehdr *ehdr, char **shname,
175 GElf_Shdr *shdr, Elf_Data **data)
176{
177 Elf_Scn *scn;
178
179 scn = elf_getscn(elf, i);
180 if (!scn)
181 return 1;
182
183 if (gelf_getshdr(scn, shdr) != shdr)
184 return 2;
185
186 *shname = elf_strptr(elf, ehdr->e_shstrndx, shdr->sh_name);
187 if (!*shname || !shdr->sh_size)
188 return 3;
189
190 *data = elf_getdata(scn, 0);
191 if (!*data || elf_getdata(scn, *data) != NULL)
192 return 4;
193
194 return 0;
195}
196
197static int parse_relo_and_apply(Elf_Data *data, Elf_Data *symbols,
198 GElf_Shdr *shdr, struct bpf_insn *insn)
199{
200 int i, nrels;
201
202 nrels = shdr->sh_size / shdr->sh_entsize;
203
204 for (i = 0; i < nrels; i++) {
205 GElf_Sym sym;
206 GElf_Rel rel;
207 unsigned int insn_idx;
208
209 gelf_getrel(data, i, &rel);
210
211 insn_idx = rel.r_offset / sizeof(struct bpf_insn);
212
213 gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym);
214
215 if (insn[insn_idx].code != (BPF_LD | BPF_IMM | BPF_DW)) {
216 printf("invalid relo for insn[%d].code 0x%x\n",
217 insn_idx, insn[insn_idx].code);
218 return 1;
219 }
220 insn[insn_idx].src_reg = BPF_PSEUDO_MAP_FD;
221 insn[insn_idx].imm = map_fd[sym.st_value / sizeof(struct bpf_map_def)];
222 }
223
224 return 0;
225}
226
227int load_bpf_file(char *path)
228{
229 int fd, i;
230 Elf *elf;
231 GElf_Ehdr ehdr;
232 GElf_Shdr shdr, shdr_prog;
233 Elf_Data *data, *data_prog, *symbols = NULL;
234 char *shname, *shname_prog;
235
236 if (elf_version(EV_CURRENT) == EV_NONE)
237 return 1;
238
239 fd = open(path, O_RDONLY, 0);
240 if (fd < 0)
241 return 1;
242
243 elf = elf_begin(fd, ELF_C_READ, NULL);
244
245 if (!elf)
246 return 1;
247
248 if (gelf_getehdr(elf, &ehdr) != &ehdr)
249 return 1;
250
251 /* clear all kprobes */
252 i = system("echo \"\" > /sys/kernel/debug/tracing/kprobe_events");
253
254 /* scan over all elf sections to get license and map info */
255 for (i = 1; i < ehdr.e_shnum; i++) {
256
257 if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
258 continue;
259
260 if (0) /* helpful for llvm debugging */
261 printf("section %d:%s data %p size %zd link %d flags %d\n",
262 i, shname, data->d_buf, data->d_size,
263 shdr.sh_link, (int) shdr.sh_flags);
264
265 if (strcmp(shname, "license") == 0) {
266 processed_sec[i] = true;
267 memcpy(license, data->d_buf, data->d_size);
268 } else if (strcmp(shname, "version") == 0) {
269 processed_sec[i] = true;
270 if (data->d_size != sizeof(int)) {
271 printf("invalid size of version section %zd\n",
272 data->d_size);
273 return 1;
274 }
275 memcpy(&kern_version, data->d_buf, sizeof(int));
276 } else if (strcmp(shname, "maps") == 0) {
277 processed_sec[i] = true;
278 if (load_maps(data->d_buf, data->d_size))
279 return 1;
280 } else if (shdr.sh_type == SHT_SYMTAB) {
281 symbols = data;
282 }
283 }
284
285 /* load programs that need map fixup (relocations) */
286 for (i = 1; i < ehdr.e_shnum; i++) {
287
288 if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
289 continue;
290 if (shdr.sh_type == SHT_REL) {
291 struct bpf_insn *insns;
292
293 if (get_sec(elf, shdr.sh_info, &ehdr, &shname_prog,
294 &shdr_prog, &data_prog))
295 continue;
296
297 insns = (struct bpf_insn *) data_prog->d_buf;
298
299 processed_sec[shdr.sh_info] = true;
300 processed_sec[i] = true;
301
302 if (parse_relo_and_apply(data, symbols, &shdr, insns))
303 continue;
304
305 if (memcmp(shname_prog, "kprobe/", 7) == 0 ||
306 memcmp(shname_prog, "kretprobe/", 10) == 0 ||
307 memcmp(shname_prog, "socket", 6) == 0)
308 load_and_attach(shname_prog, insns, data_prog->d_size);
309 }
310 }
311
312 /* load programs that don't use maps */
313 for (i = 1; i < ehdr.e_shnum; i++) {
314
315 if (processed_sec[i])
316 continue;
317
318 if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
319 continue;
320
321 if (memcmp(shname, "kprobe/", 7) == 0 ||
322 memcmp(shname, "kretprobe/", 10) == 0 ||
323 memcmp(shname, "socket", 6) == 0)
324 load_and_attach(shname, data->d_buf, data->d_size);
325 }
326
327 close(fd);
328 return 0;
329}
330
331void read_trace_pipe(void)
332{
333 int trace_fd;
334
335 trace_fd = open(DEBUGFS "trace_pipe", O_RDONLY, 0);
336 if (trace_fd < 0)
337 return;
338
339 while (1) {
340 static char buf[4096];
341 ssize_t sz;
342
343 sz = read(trace_fd, buf, sizeof(buf));
344 if (sz > 0) {
345 buf[sz] = 0;
346 puts(buf);
347 }
348 }
349}
350
351#define MAX_SYMS 300000
352static struct ksym syms[MAX_SYMS];
353static int sym_cnt;
354
355static int ksym_cmp(const void *p1, const void *p2)
356{
357 return ((struct ksym *)p1)->addr - ((struct ksym *)p2)->addr;
358}
359
360int load_kallsyms(void)
361{
362 FILE *f = fopen("/proc/kallsyms", "r");
363 char func[256], buf[256];
364 char symbol;
365 void *addr;
366 int i = 0;
367
368 if (!f)
369 return -ENOENT;
370
371 while (!feof(f)) {
372 if (!fgets(buf, sizeof(buf), f))
373 break;
374 if (sscanf(buf, "%p %c %s", &addr, &symbol, func) != 3)
375 break;
376 if (!addr)
377 continue;
378 syms[i].addr = (long) addr;
379 syms[i].name = strdup(func);
380 i++;
381 }
382 sym_cnt = i;
383 qsort(syms, sym_cnt, sizeof(struct ksym), ksym_cmp);
384 return 0;
385}
386
387struct ksym *ksym_search(long key)
388{
389 int start = 0, end = sym_cnt;
390 int result;
391
392 while (start < end) {
393 size_t mid = start + (end - start) / 2;
394
395 result = key - syms[mid].addr;
396 if (result < 0)
397 end = mid;
398 else if (result > 0)
399 start = mid + 1;
400 else
401 return &syms[mid];
402 }
403
404 if (start >= 1 && syms[start - 1].addr < key &&
405 key < syms[start].addr)
406 /* valid ksym */
407 return &syms[start - 1];
408
409 /* out of range. return _stext */
410 return &syms[0];
411}