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 "libbpf.h"
20 #include "bpf_helpers.h"
21 #include "bpf_load.h"
22
23 #define DEBUGFS "/sys/kernel/debug/tracing/"
24
25 static char license[128];
26 static int kern_version;
27 static bool processed_sec[128];
28 int map_fd[MAX_MAPS];
29 int prog_fd[MAX_PROGS];
30 int event_fd[MAX_PROGS];
31 int prog_cnt;
32
load_and_attach(const char * event,struct bpf_insn * prog,int size)33 static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
34 {
35 bool is_socket = strncmp(event, "socket", 6) == 0;
36 bool is_kprobe = strncmp(event, "kprobe/", 7) == 0;
37 bool is_kretprobe = strncmp(event, "kretprobe/", 10) == 0;
38 enum bpf_prog_type prog_type;
39 char buf[256];
40 int fd, efd, err, id;
41 struct perf_event_attr attr = {};
42
43 attr.type = PERF_TYPE_TRACEPOINT;
44 attr.sample_type = PERF_SAMPLE_RAW;
45 attr.sample_period = 1;
46 attr.wakeup_events = 1;
47
48 if (is_socket) {
49 prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
50 } else if (is_kprobe || is_kretprobe) {
51 prog_type = BPF_PROG_TYPE_KPROBE;
52 } else {
53 printf("Unknown event '%s'\n", event);
54 return -1;
55 }
56
57 if (is_kprobe || is_kretprobe) {
58 if (is_kprobe)
59 event += 7;
60 else
61 event += 10;
62
63 snprintf(buf, sizeof(buf),
64 "echo '%c:%s %s' >> /sys/kernel/debug/tracing/kprobe_events",
65 is_kprobe ? 'p' : 'r', event, event);
66 err = system(buf);
67 if (err < 0) {
68 printf("failed to create kprobe '%s' error '%s'\n",
69 event, strerror(errno));
70 return -1;
71 }
72 }
73
74 fd = bpf_prog_load(prog_type, prog, size, license, kern_version);
75
76 if (fd < 0) {
77 printf("bpf_prog_load() err=%d\n%s", errno, bpf_log_buf);
78 return -1;
79 }
80
81 prog_fd[prog_cnt++] = fd;
82
83 if (is_socket)
84 return 0;
85
86 strcpy(buf, DEBUGFS);
87 strcat(buf, "events/kprobes/");
88 strcat(buf, event);
89 strcat(buf, "/id");
90
91 efd = open(buf, O_RDONLY, 0);
92 if (efd < 0) {
93 printf("failed to open event %s\n", event);
94 return -1;
95 }
96
97 err = read(efd, buf, sizeof(buf));
98 if (err < 0 || err >= sizeof(buf)) {
99 printf("read from '%s' failed '%s'\n", event, strerror(errno));
100 return -1;
101 }
102
103 close(efd);
104
105 buf[err] = 0;
106 id = atoi(buf);
107 attr.config = id;
108
109 efd = perf_event_open(&attr, -1/*pid*/, 0/*cpu*/, -1/*group_fd*/, 0);
110 if (efd < 0) {
111 printf("event %d fd %d err %s\n", id, efd, strerror(errno));
112 return -1;
113 }
114 event_fd[prog_cnt - 1] = efd;
115 ioctl(efd, PERF_EVENT_IOC_ENABLE, 0);
116 ioctl(efd, PERF_EVENT_IOC_SET_BPF, fd);
117
118 return 0;
119 }
120
load_maps(struct bpf_map_def * maps,int len)121 static int load_maps(struct bpf_map_def *maps, int len)
122 {
123 int i;
124
125 for (i = 0; i < len / sizeof(struct bpf_map_def); i++) {
126
127 map_fd[i] = bpf_create_map(maps[i].type,
128 maps[i].key_size,
129 maps[i].value_size,
130 maps[i].max_entries);
131 if (map_fd[i] < 0)
132 return 1;
133 }
134 return 0;
135 }
136
get_sec(Elf * elf,int i,GElf_Ehdr * ehdr,char ** shname,GElf_Shdr * shdr,Elf_Data ** data)137 static int get_sec(Elf *elf, int i, GElf_Ehdr *ehdr, char **shname,
138 GElf_Shdr *shdr, Elf_Data **data)
139 {
140 Elf_Scn *scn;
141
142 scn = elf_getscn(elf, i);
143 if (!scn)
144 return 1;
145
146 if (gelf_getshdr(scn, shdr) != shdr)
147 return 2;
148
149 *shname = elf_strptr(elf, ehdr->e_shstrndx, shdr->sh_name);
150 if (!*shname || !shdr->sh_size)
151 return 3;
152
153 *data = elf_getdata(scn, 0);
154 if (!*data || elf_getdata(scn, *data) != NULL)
155 return 4;
156
157 return 0;
158 }
159
parse_relo_and_apply(Elf_Data * data,Elf_Data * symbols,GElf_Shdr * shdr,struct bpf_insn * insn)160 static int parse_relo_and_apply(Elf_Data *data, Elf_Data *symbols,
161 GElf_Shdr *shdr, struct bpf_insn *insn)
162 {
163 int i, nrels;
164
165 nrels = shdr->sh_size / shdr->sh_entsize;
166
167 for (i = 0; i < nrels; i++) {
168 GElf_Sym sym;
169 GElf_Rel rel;
170 unsigned int insn_idx;
171
172 gelf_getrel(data, i, &rel);
173
174 insn_idx = rel.r_offset / sizeof(struct bpf_insn);
175
176 gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym);
177
178 if (insn[insn_idx].code != (BPF_LD | BPF_IMM | BPF_DW)) {
179 printf("invalid relo for insn[%d].code 0x%x\n",
180 insn_idx, insn[insn_idx].code);
181 return 1;
182 }
183 insn[insn_idx].src_reg = BPF_PSEUDO_MAP_FD;
184 insn[insn_idx].imm = map_fd[sym.st_value / sizeof(struct bpf_map_def)];
185 }
186
187 return 0;
188 }
189
load_bpf_file(char * path)190 int load_bpf_file(char *path)
191 {
192 int fd, i;
193 Elf *elf;
194 GElf_Ehdr ehdr;
195 GElf_Shdr shdr, shdr_prog;
196 Elf_Data *data, *data_prog, *symbols = NULL;
197 char *shname, *shname_prog;
198
199 if (elf_version(EV_CURRENT) == EV_NONE)
200 return 1;
201
202 fd = open(path, O_RDONLY, 0);
203 if (fd < 0)
204 return 1;
205
206 elf = elf_begin(fd, ELF_C_READ, NULL);
207
208 if (!elf)
209 return 1;
210
211 if (gelf_getehdr(elf, &ehdr) != &ehdr)
212 return 1;
213
214 /* clear all kprobes */
215 i = system("echo \"\" > /sys/kernel/debug/tracing/kprobe_events");
216
217 /* scan over all elf sections to get license and map info */
218 for (i = 1; i < ehdr.e_shnum; i++) {
219
220 if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
221 continue;
222
223 if (0) /* helpful for llvm debugging */
224 printf("section %d:%s data %p size %zd link %d flags %d\n",
225 i, shname, data->d_buf, data->d_size,
226 shdr.sh_link, (int) shdr.sh_flags);
227
228 if (strcmp(shname, "license") == 0) {
229 processed_sec[i] = true;
230 memcpy(license, data->d_buf, data->d_size);
231 } else if (strcmp(shname, "version") == 0) {
232 processed_sec[i] = true;
233 if (data->d_size != sizeof(int)) {
234 printf("invalid size of version section %zd\n",
235 data->d_size);
236 return 1;
237 }
238 memcpy(&kern_version, data->d_buf, sizeof(int));
239 } else if (strcmp(shname, "maps") == 0) {
240 processed_sec[i] = true;
241 if (load_maps(data->d_buf, data->d_size))
242 return 1;
243 } else if (shdr.sh_type == SHT_SYMTAB) {
244 symbols = data;
245 }
246 }
247
248 /* load programs that need map fixup (relocations) */
249 for (i = 1; i < ehdr.e_shnum; i++) {
250
251 if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
252 continue;
253 if (shdr.sh_type == SHT_REL) {
254 struct bpf_insn *insns;
255
256 if (get_sec(elf, shdr.sh_info, &ehdr, &shname_prog,
257 &shdr_prog, &data_prog))
258 continue;
259
260 insns = (struct bpf_insn *) data_prog->d_buf;
261
262 processed_sec[shdr.sh_info] = true;
263 processed_sec[i] = true;
264
265 if (parse_relo_and_apply(data, symbols, &shdr, insns))
266 continue;
267
268 if (memcmp(shname_prog, "kprobe/", 7) == 0 ||
269 memcmp(shname_prog, "kretprobe/", 10) == 0 ||
270 memcmp(shname_prog, "socket", 6) == 0)
271 load_and_attach(shname_prog, insns, data_prog->d_size);
272 }
273 }
274
275 /* load programs that don't use maps */
276 for (i = 1; i < ehdr.e_shnum; i++) {
277
278 if (processed_sec[i])
279 continue;
280
281 if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
282 continue;
283
284 if (memcmp(shname, "kprobe/", 7) == 0 ||
285 memcmp(shname, "kretprobe/", 10) == 0 ||
286 memcmp(shname, "socket", 6) == 0)
287 load_and_attach(shname, data->d_buf, data->d_size);
288 }
289
290 close(fd);
291 return 0;
292 }
293
read_trace_pipe(void)294 void read_trace_pipe(void)
295 {
296 int trace_fd;
297
298 trace_fd = open(DEBUGFS "trace_pipe", O_RDONLY, 0);
299 if (trace_fd < 0)
300 return;
301
302 while (1) {
303 static char buf[4096];
304 ssize_t sz;
305
306 sz = read(trace_fd, buf, sizeof(buf));
307 if (sz > 0) {
308 buf[sz] = 0;
309 puts(buf);
310 }
311 }
312 }
313