1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2010 The FreeBSD Foundation
5 * All rights reserved.
6 *
7 * This software was developed by Rui Paulo under sponsorship from the
8 * FreeBSD Foundation.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
34
35 #include <sys/param.h>
36 #include <sys/sysctl.h>
37 #include <sys/user.h>
38
39 #include <assert.h>
40 #include <err.h>
41 #include <fcntl.h>
42 #include <limits.h>
43 #include <stdio.h>
44 #include <stdlib.h>
45 #include <string.h>
46 #include <unistd.h>
47
48 #include <machine/elf.h>
49
50 #include <libelf.h>
51 #include <libproc.h>
52 #include <libprocstat.h>
53 #include <libutil.h>
54
55 #include "rtld_db.h"
56
57 static int _librtld_db_debug = 0;
58 #define DPRINTF(...) do { \
59 if (_librtld_db_debug) { \
60 fprintf(stderr, "librtld_db: DEBUG: "); \
61 fprintf(stderr, __VA_ARGS__); \
62 } \
63 } while (0)
64
65 void
rd_delete(rd_agent_t * rdap)66 rd_delete(rd_agent_t *rdap)
67 {
68
69 if (rdap->rda_procstat != NULL)
70 procstat_close(rdap->rda_procstat);
71 free(rdap);
72 }
73
74 const char *
rd_errstr(rd_err_e rderr)75 rd_errstr(rd_err_e rderr)
76 {
77
78 switch (rderr) {
79 case RD_ERR:
80 return "generic error";
81 case RD_OK:
82 return "no error";
83 case RD_NOCAPAB:
84 return "capability not supported";
85 case RD_DBERR:
86 return "database error";
87 case RD_NOBASE:
88 return "NOBASE";
89 case RD_NOMAPS:
90 return "NOMAPS";
91 default:
92 return "unknown error";
93 }
94 }
95
96 rd_err_e
rd_event_addr(rd_agent_t * rdap,rd_event_e event,rd_notify_t * notify)97 rd_event_addr(rd_agent_t *rdap, rd_event_e event, rd_notify_t *notify)
98 {
99 rd_err_e ret;
100
101 DPRINTF("%s rdap %p event %d notify %p\n", __func__, rdap, event,
102 notify);
103
104 ret = RD_OK;
105 switch (event) {
106 case RD_NONE:
107 break;
108 case RD_PREINIT:
109 notify->type = RD_NOTIFY_BPT;
110 notify->u.bptaddr = rdap->rda_preinit_addr;
111 break;
112 case RD_POSTINIT:
113 notify->type = RD_NOTIFY_BPT;
114 notify->u.bptaddr = rdap->rda_postinit_addr;
115 break;
116 case RD_DLACTIVITY:
117 notify->type = RD_NOTIFY_BPT;
118 notify->u.bptaddr = rdap->rda_dlactivity_addr;
119 break;
120 default:
121 ret = RD_ERR;
122 break;
123 }
124 return (ret);
125 }
126
127 rd_err_e
rd_event_enable(rd_agent_t * rdap __unused,int onoff)128 rd_event_enable(rd_agent_t *rdap __unused, int onoff)
129 {
130 DPRINTF("%s onoff %d\n", __func__, onoff);
131
132 return (RD_OK);
133 }
134
135 rd_err_e
rd_event_getmsg(rd_agent_t * rdap __unused,rd_event_msg_t * msg)136 rd_event_getmsg(rd_agent_t *rdap __unused, rd_event_msg_t *msg)
137 {
138 DPRINTF("%s\n", __func__);
139
140 msg->type = RD_POSTINIT;
141 msg->u.state = RD_CONSISTENT;
142
143 return (RD_OK);
144 }
145
146 rd_err_e
rd_init(int version)147 rd_init(int version)
148 {
149 char *debug = NULL;
150
151 if (version == RD_VERSION) {
152 debug = getenv("LIBRTLD_DB_DEBUG");
153 _librtld_db_debug = debug ? atoi(debug) : 0;
154 return (RD_OK);
155 } else
156 return (RD_NOCAPAB);
157 }
158
159 rd_err_e
rd_loadobj_iter(rd_agent_t * rdap,rl_iter_f * cb,void * clnt_data)160 rd_loadobj_iter(rd_agent_t *rdap, rl_iter_f *cb, void *clnt_data)
161 {
162 struct kinfo_vmentry *kves, *kve;
163 const char *path;
164 uint64_t fileid;
165 rd_loadobj_t rdl;
166 rd_err_e ret;
167 uintptr_t base;
168 uint32_t offset;
169 int cnt, i;
170
171 DPRINTF("%s\n", __func__);
172
173 if ((kves = kinfo_getvmmap(proc_getpid(rdap->rda_php), &cnt)) == NULL) {
174 warn("ERROR: kinfo_getvmmap() failed");
175 return (RD_ERR);
176 }
177
178 base = 0;
179 fileid = 0;
180 path = NULL;
181 ret = RD_OK;
182 for (i = 0; i < cnt; i++) {
183 kve = &kves[i];
184 /*
185 * Cache the base offset of the file mapping. The kve_offset
186 * field gives the file offset of a particular mapping into the
187 * file, but we want the mapping offset relative to the base
188 * mapping.
189 */
190 if (kve->kve_type == KVME_TYPE_VNODE) {
191 if (kve->kve_vn_fileid != fileid) {
192 base = kve->kve_start;
193 fileid = kve->kve_vn_fileid;
194 }
195 path = kve->kve_path;
196 offset = kve->kve_start - base;
197 } else {
198 path = NULL;
199 offset = 0;
200 }
201 memset(&rdl, 0, sizeof(rdl));
202 /*
203 * Map the kinfo_vmentry struct to the rd_loadobj structure.
204 */
205 rdl.rdl_saddr = kve->kve_start;
206 rdl.rdl_eaddr = kve->kve_end;
207 rdl.rdl_offset = offset;
208 if (kve->kve_protection & KVME_PROT_READ)
209 rdl.rdl_prot |= RD_RDL_R;
210 if (kve->kve_protection & KVME_PROT_WRITE)
211 rdl.rdl_prot |= RD_RDL_W;
212 if (kve->kve_protection & KVME_PROT_EXEC)
213 rdl.rdl_prot |= RD_RDL_X;
214 if (path != NULL)
215 strlcpy(rdl.rdl_path, path, sizeof(rdl.rdl_path));
216 if ((*cb)(&rdl, clnt_data) != 0) {
217 ret = RD_ERR;
218 break;
219 }
220 }
221 free(kves);
222 return (ret);
223 }
224
225 void
rd_log(const int onoff)226 rd_log(const int onoff)
227 {
228 DPRINTF("%s\n", __func__);
229
230 (void)onoff;
231 }
232
233 rd_agent_t *
rd_new(struct proc_handle * php)234 rd_new(struct proc_handle *php)
235 {
236 rd_agent_t *rdap;
237
238 rdap = malloc(sizeof(*rdap));
239 if (rdap == NULL)
240 return (NULL);
241
242 memset(rdap, 0, sizeof(rd_agent_t));
243 rdap->rda_php = php;
244 rdap->rda_procstat = procstat_open_sysctl();
245
246 if (rd_reset(rdap) != RD_OK) {
247 rd_delete(rdap);
248 rdap = NULL;
249 }
250 return (rdap);
251 }
252
253 rd_err_e
rd_objpad_enable(rd_agent_t * rdap,size_t padsize)254 rd_objpad_enable(rd_agent_t *rdap, size_t padsize)
255 {
256 DPRINTF("%s\n", __func__);
257
258 (void)rdap;
259 (void)padsize;
260
261 return (RD_ERR);
262 }
263
264 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)265 rd_plt_resolution(rd_agent_t *rdap, uintptr_t pc, struct proc *proc,
266 uintptr_t plt_base, rd_plt_info_t *rpi)
267 {
268 DPRINTF("%s\n", __func__);
269
270 (void)rdap;
271 (void)pc;
272 (void)proc;
273 (void)plt_base;
274 (void)rpi;
275
276 return (RD_ERR);
277 }
278
279 static int
rtld_syms(rd_agent_t * rdap,const char * rtldpath,u_long base)280 rtld_syms(rd_agent_t *rdap, const char *rtldpath, u_long base)
281 {
282 GElf_Shdr shdr;
283 GElf_Sym sym;
284 Elf *e;
285 Elf_Data *data;
286 Elf_Scn *scn;
287 const char *symname;
288 Elf64_Word strscnidx;
289 int fd, i, ret;
290
291 ret = 1;
292 e = NULL;
293
294 fd = open(rtldpath, O_RDONLY);
295 if (fd < 0)
296 goto err;
297
298 if (elf_version(EV_CURRENT) == EV_NONE)
299 goto err;
300 e = elf_begin(fd, ELF_C_READ, NULL);
301 if (e == NULL)
302 goto err;
303
304 scn = NULL;
305 while ((scn = elf_nextscn(e, scn)) != NULL) {
306 gelf_getshdr(scn, &shdr);
307 if (shdr.sh_type == SHT_DYNSYM)
308 break;
309 }
310 if (scn == NULL)
311 goto err;
312
313 strscnidx = shdr.sh_link;
314 data = elf_getdata(scn, NULL);
315 if (data == NULL)
316 goto err;
317
318 for (i = 0; gelf_getsym(data, i, &sym) != NULL; i++) {
319 if (GELF_ST_TYPE(sym.st_info) != STT_FUNC ||
320 GELF_ST_BIND(sym.st_info) != STB_GLOBAL)
321 continue;
322 symname = elf_strptr(e, strscnidx, sym.st_name);
323 if (symname == NULL)
324 continue;
325
326 if (strcmp(symname, "r_debug_state") == 0) {
327 rdap->rda_preinit_addr = sym.st_value + base;
328 rdap->rda_dlactivity_addr = sym.st_value + base;
329 } else if (strcmp(symname, "_r_debug_postinit") == 0) {
330 rdap->rda_postinit_addr = sym.st_value + base;
331 }
332 }
333
334 if (rdap->rda_preinit_addr != 0 &&
335 rdap->rda_postinit_addr != 0 &&
336 rdap->rda_dlactivity_addr != 0)
337 ret = 0;
338
339 err:
340 if (e != NULL)
341 (void)elf_end(e);
342 if (fd >= 0)
343 (void)close(fd);
344 return (ret);
345 }
346
347 rd_err_e
rd_reset(rd_agent_t * rdap)348 rd_reset(rd_agent_t *rdap)
349 {
350 struct kinfo_proc *kp;
351 struct kinfo_vmentry *kve;
352 Elf_Auxinfo *auxv;
353 const char *rtldpath;
354 u_long base;
355 rd_err_e rderr;
356 int count, i;
357
358 kp = NULL;
359 auxv = NULL;
360 kve = NULL;
361 rderr = RD_ERR;
362
363 kp = procstat_getprocs(rdap->rda_procstat, KERN_PROC_PID,
364 proc_getpid(rdap->rda_php), &count);
365 if (kp == NULL)
366 return (RD_ERR);
367 assert(count == 1);
368
369 auxv = procstat_getauxv(rdap->rda_procstat, kp, &count);
370 if (auxv == NULL)
371 goto err;
372
373 base = 0;
374 for (i = 0; i < count; i++) {
375 if (auxv[i].a_type == AT_BASE) {
376 base = auxv[i].a_un.a_val;
377 break;
378 }
379 }
380 if (i == count)
381 goto err;
382
383 rtldpath = NULL;
384 kve = procstat_getvmmap(rdap->rda_procstat, kp, &count);
385 if (kve == NULL)
386 goto err;
387 for (i = 0; i < count; i++) {
388 if (kve[i].kve_start == base) {
389 rtldpath = kve[i].kve_path;
390 break;
391 }
392 }
393 if (i == count)
394 goto err;
395
396 if (rtld_syms(rdap, rtldpath, base) != 0)
397 goto err;
398
399 rderr = RD_OK;
400
401 err:
402 if (kve != NULL)
403 procstat_freevmmap(rdap->rda_procstat, kve);
404 if (auxv != NULL)
405 procstat_freeauxv(rdap->rda_procstat, auxv);
406 if (kp != NULL)
407 procstat_freeprocs(rdap->rda_procstat, kp);
408 return (rderr);
409 }
410