1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2010 The FreeBSD Foundation
5 *
6 * This software was developed by Rui Paulo under sponsorship from the
7 * FreeBSD Foundation.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31 #include <sys/param.h>
32 #include <sys/sysctl.h>
33 #include <sys/user.h>
34
35 #include <assert.h>
36 #include <err.h>
37 #include <fcntl.h>
38 #include <limits.h>
39 #include <stdio.h>
40 #include <stdlib.h>
41 #include <string.h>
42 #include <unistd.h>
43
44 #include <machine/elf.h>
45
46 #include <libelf.h>
47 #include <libproc.h>
48 #include <libprocstat.h>
49 #include <libutil.h>
50
51 #include "rtld_db.h"
52
53 static int _librtld_db_debug = 0;
54 #define DPRINTF(...) do { \
55 if (_librtld_db_debug) { \
56 fprintf(stderr, "librtld_db: DEBUG: "); \
57 fprintf(stderr, __VA_ARGS__); \
58 } \
59 } while (0)
60
61 void
rd_delete(rd_agent_t * rdap)62 rd_delete(rd_agent_t *rdap)
63 {
64
65 if (rdap->rda_procstat != NULL)
66 procstat_close(rdap->rda_procstat);
67 free(rdap);
68 }
69
70 const char *
rd_errstr(rd_err_e rderr)71 rd_errstr(rd_err_e rderr)
72 {
73
74 switch (rderr) {
75 case RD_ERR:
76 return "generic error";
77 case RD_OK:
78 return "no error";
79 case RD_NOCAPAB:
80 return "capability not supported";
81 case RD_DBERR:
82 return "database error";
83 case RD_NOBASE:
84 return "NOBASE";
85 case RD_NOMAPS:
86 return "NOMAPS";
87 default:
88 return "unknown error";
89 }
90 }
91
92 rd_err_e
rd_event_addr(rd_agent_t * rdap,rd_event_e event,rd_notify_t * notify)93 rd_event_addr(rd_agent_t *rdap, rd_event_e event, rd_notify_t *notify)
94 {
95 rd_err_e ret;
96
97 DPRINTF("%s rdap %p event %d notify %p\n", __func__, rdap, event,
98 notify);
99
100 ret = RD_OK;
101 switch (event) {
102 case RD_NONE:
103 break;
104 case RD_PREINIT:
105 notify->type = RD_NOTIFY_BPT;
106 notify->u.bptaddr = rdap->rda_preinit_addr;
107 break;
108 case RD_POSTINIT:
109 notify->type = RD_NOTIFY_BPT;
110 notify->u.bptaddr = rdap->rda_postinit_addr;
111 break;
112 case RD_DLACTIVITY:
113 notify->type = RD_NOTIFY_BPT;
114 notify->u.bptaddr = rdap->rda_dlactivity_addr;
115 break;
116 default:
117 ret = RD_ERR;
118 break;
119 }
120 return (ret);
121 }
122
123 rd_err_e
rd_event_enable(rd_agent_t * rdap __unused,int onoff)124 rd_event_enable(rd_agent_t *rdap __unused, int onoff)
125 {
126 DPRINTF("%s onoff %d\n", __func__, onoff);
127
128 return (RD_OK);
129 }
130
131 rd_err_e
rd_event_getmsg(rd_agent_t * rdap __unused,rd_event_msg_t * msg)132 rd_event_getmsg(rd_agent_t *rdap __unused, rd_event_msg_t *msg)
133 {
134 DPRINTF("%s\n", __func__);
135
136 msg->type = RD_POSTINIT;
137 msg->u.state = RD_CONSISTENT;
138
139 return (RD_OK);
140 }
141
142 rd_err_e
rd_init(int version)143 rd_init(int version)
144 {
145 char *debug = NULL;
146
147 if (version == RD_VERSION) {
148 debug = getenv("LIBRTLD_DB_DEBUG");
149 _librtld_db_debug = debug ? atoi(debug) : 0;
150 return (RD_OK);
151 } else
152 return (RD_NOCAPAB);
153 }
154
155 rd_err_e
rd_loadobj_iter(rd_agent_t * rdap,rl_iter_f * cb,void * clnt_data)156 rd_loadobj_iter(rd_agent_t *rdap, rl_iter_f *cb, void *clnt_data)
157 {
158 struct kinfo_vmentry *kves, *kve;
159 const char *path;
160 uint64_t fileid;
161 rd_loadobj_t rdl;
162 rd_err_e ret;
163 uintptr_t base;
164 uint32_t offset;
165 int cnt, i;
166
167 DPRINTF("%s\n", __func__);
168
169 if ((kves = kinfo_getvmmap(proc_getpid(rdap->rda_php), &cnt)) == NULL) {
170 warn("ERROR: kinfo_getvmmap() failed");
171 return (RD_ERR);
172 }
173
174 base = 0;
175 fileid = 0;
176 path = NULL;
177 ret = RD_OK;
178 for (i = 0; i < cnt; i++) {
179 kve = &kves[i];
180 /*
181 * Cache the base offset of the file mapping. The kve_offset
182 * field gives the file offset of a particular mapping into the
183 * file, but we want the mapping offset relative to the base
184 * mapping.
185 */
186 if (kve->kve_type == KVME_TYPE_VNODE) {
187 if (kve->kve_vn_fileid != fileid) {
188 base = kve->kve_start;
189 fileid = kve->kve_vn_fileid;
190 }
191 path = kve->kve_path;
192 offset = kve->kve_start - base;
193 } else {
194 path = NULL;
195 offset = 0;
196 }
197 memset(&rdl, 0, sizeof(rdl));
198 /*
199 * Map the kinfo_vmentry struct to the rd_loadobj structure.
200 */
201 rdl.rdl_saddr = kve->kve_start;
202 rdl.rdl_eaddr = kve->kve_end;
203 rdl.rdl_offset = offset;
204 if (kve->kve_protection & KVME_PROT_READ)
205 rdl.rdl_prot |= RD_RDL_R;
206 if (kve->kve_protection & KVME_PROT_WRITE)
207 rdl.rdl_prot |= RD_RDL_W;
208 if (kve->kve_protection & KVME_PROT_EXEC)
209 rdl.rdl_prot |= RD_RDL_X;
210 if (path != NULL)
211 strlcpy(rdl.rdl_path, path, sizeof(rdl.rdl_path));
212 if ((*cb)(&rdl, clnt_data) != 0) {
213 ret = RD_ERR;
214 break;
215 }
216 }
217 free(kves);
218 return (ret);
219 }
220
221 void
rd_log(const int onoff)222 rd_log(const int onoff)
223 {
224 DPRINTF("%s\n", __func__);
225
226 (void)onoff;
227 }
228
229 rd_agent_t *
rd_new(struct proc_handle * php)230 rd_new(struct proc_handle *php)
231 {
232 rd_agent_t *rdap;
233
234 rdap = malloc(sizeof(*rdap));
235 if (rdap == NULL)
236 return (NULL);
237
238 memset(rdap, 0, sizeof(rd_agent_t));
239 rdap->rda_php = php;
240 rdap->rda_procstat = procstat_open_sysctl();
241
242 if (rd_reset(rdap) != RD_OK) {
243 rd_delete(rdap);
244 rdap = NULL;
245 }
246 return (rdap);
247 }
248
249 rd_err_e
rd_objpad_enable(rd_agent_t * rdap,size_t padsize)250 rd_objpad_enable(rd_agent_t *rdap, size_t padsize)
251 {
252 DPRINTF("%s\n", __func__);
253
254 (void)rdap;
255 (void)padsize;
256
257 return (RD_ERR);
258 }
259
260 rd_err_e
rd_plt_resolution(rd_agent_t * rdap,uintptr_t pc,struct proc * proc,uintptr_t plt_base,rd_plt_info_t * rpi)261 rd_plt_resolution(rd_agent_t *rdap, uintptr_t pc, struct proc *proc,
262 uintptr_t plt_base, rd_plt_info_t *rpi)
263 {
264 DPRINTF("%s\n", __func__);
265
266 (void)rdap;
267 (void)pc;
268 (void)proc;
269 (void)plt_base;
270 (void)rpi;
271
272 return (RD_ERR);
273 }
274
275 static int
rtld_syms(rd_agent_t * rdap,const char * rtldpath,u_long base)276 rtld_syms(rd_agent_t *rdap, const char *rtldpath, u_long base)
277 {
278 GElf_Shdr shdr;
279 GElf_Sym sym;
280 Elf *e;
281 Elf_Data *data;
282 Elf_Scn *scn;
283 const char *symname;
284 Elf64_Word strscnidx;
285 int fd, i, ret;
286
287 ret = 1;
288 e = NULL;
289
290 fd = open(rtldpath, O_RDONLY);
291 if (fd < 0)
292 goto err;
293
294 if (elf_version(EV_CURRENT) == EV_NONE)
295 goto err;
296 e = elf_begin(fd, ELF_C_READ, NULL);
297 if (e == NULL)
298 goto err;
299
300 scn = NULL;
301 while ((scn = elf_nextscn(e, scn)) != NULL) {
302 gelf_getshdr(scn, &shdr);
303 if (shdr.sh_type == SHT_DYNSYM)
304 break;
305 }
306 if (scn == NULL)
307 goto err;
308
309 strscnidx = shdr.sh_link;
310 data = elf_getdata(scn, NULL);
311 if (data == NULL)
312 goto err;
313
314 for (i = 0; gelf_getsym(data, i, &sym) != NULL; i++) {
315 if (GELF_ST_TYPE(sym.st_info) != STT_FUNC ||
316 GELF_ST_BIND(sym.st_info) != STB_GLOBAL)
317 continue;
318 symname = elf_strptr(e, strscnidx, sym.st_name);
319 if (symname == NULL)
320 continue;
321
322 if (strcmp(symname, "r_debug_state") == 0) {
323 rdap->rda_preinit_addr = sym.st_value + base;
324 rdap->rda_dlactivity_addr = sym.st_value + base;
325 } else if (strcmp(symname, "_r_debug_postinit") == 0) {
326 rdap->rda_postinit_addr = sym.st_value + base;
327 }
328 }
329
330 if (rdap->rda_preinit_addr != 0 &&
331 rdap->rda_postinit_addr != 0 &&
332 rdap->rda_dlactivity_addr != 0)
333 ret = 0;
334
335 err:
336 if (e != NULL)
337 (void)elf_end(e);
338 if (fd >= 0)
339 (void)close(fd);
340 return (ret);
341 }
342
343 rd_err_e
rd_reset(rd_agent_t * rdap)344 rd_reset(rd_agent_t *rdap)
345 {
346 struct kinfo_proc *kp;
347 struct kinfo_vmentry *kve;
348 Elf_Auxinfo *auxv;
349 const char *rtldpath;
350 u_long base;
351 rd_err_e rderr;
352 int count, i;
353
354 kp = NULL;
355 auxv = NULL;
356 kve = NULL;
357 rderr = RD_ERR;
358
359 kp = procstat_getprocs(rdap->rda_procstat, KERN_PROC_PID,
360 proc_getpid(rdap->rda_php), &count);
361 if (kp == NULL)
362 return (RD_ERR);
363 assert(count == 1);
364
365 auxv = procstat_getauxv(rdap->rda_procstat, kp, &count);
366 if (auxv == NULL)
367 goto err;
368
369 base = 0;
370 for (i = 0; i < count; i++) {
371 if (auxv[i].a_type == AT_BASE) {
372 base = auxv[i].a_un.a_val;
373 break;
374 }
375 }
376 if (i == count)
377 goto err;
378
379 rtldpath = NULL;
380 kve = procstat_getvmmap(rdap->rda_procstat, kp, &count);
381 if (kve == NULL)
382 goto err;
383 for (i = 0; i < count; i++) {
384 if (kve[i].kve_start == base) {
385 rtldpath = kve[i].kve_path;
386 break;
387 }
388 }
389 if (i == count)
390 goto err;
391
392 if (rtld_syms(rdap, rtldpath, base) != 0)
393 goto err;
394
395 rderr = RD_OK;
396
397 err:
398 if (kve != NULL)
399 procstat_freevmmap(rdap->rda_procstat, kve);
400 if (auxv != NULL)
401 procstat_freeauxv(rdap->rda_procstat, auxv);
402 if (kp != NULL)
403 procstat_freeprocs(rdap->rda_procstat, kp);
404 return (rderr);
405 }
406