1 /*
2 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3 * Licensed under the GPL
4 */
5
6 #include <stdio.h>
7 #include <stdlib.h>
8 #include <stdarg.h>
9 #include <unistd.h>
10 #include <errno.h>
11 #include <fcntl.h>
12 #include <sched.h>
13 #include <signal.h>
14 #include <string.h>
15 #include <sys/mman.h>
16 #include <sys/ptrace.h>
17 #include <sys/stat.h>
18 #include <sys/wait.h>
19 #include <asm/unistd.h>
20 #include "init.h"
21 #include "kern_constants.h"
22 #include "os.h"
23 #include "mem_user.h"
24 #include "ptrace_user.h"
25 #include "registers.h"
26 #include "skas.h"
27 #include "skas_ptrace.h"
28
ptrace_child(void)29 static void ptrace_child(void)
30 {
31 int ret;
32 /* Calling os_getpid because some libcs cached getpid incorrectly */
33 int pid = os_getpid(), ppid = getppid();
34 int sc_result;
35
36 if (change_sig(SIGWINCH, 0) < 0 ||
37 ptrace(PTRACE_TRACEME, 0, 0, 0) < 0) {
38 perror("ptrace");
39 kill(pid, SIGKILL);
40 }
41 kill(pid, SIGSTOP);
42
43 /*
44 * This syscall will be intercepted by the parent. Don't call more than
45 * once, please.
46 */
47 sc_result = os_getpid();
48
49 if (sc_result == pid)
50 /* Nothing modified by the parent, we are running normally. */
51 ret = 1;
52 else if (sc_result == ppid)
53 /*
54 * Expected in check_ptrace and check_sysemu when they succeed
55 * in modifying the stack frame
56 */
57 ret = 0;
58 else
59 /* Serious trouble! This could be caused by a bug in host 2.6
60 * SKAS3/2.6 patch before release -V6, together with a bug in
61 * the UML code itself.
62 */
63 ret = 2;
64
65 exit(ret);
66 }
67
fatal_perror(const char * str)68 static void fatal_perror(const char *str)
69 {
70 perror(str);
71 exit(1);
72 }
73
fatal(char * fmt,...)74 static void fatal(char *fmt, ...)
75 {
76 va_list list;
77
78 va_start(list, fmt);
79 vfprintf(stderr, fmt, list);
80 va_end(list);
81
82 exit(1);
83 }
84
non_fatal(char * fmt,...)85 static void non_fatal(char *fmt, ...)
86 {
87 va_list list;
88
89 va_start(list, fmt);
90 vfprintf(stderr, fmt, list);
91 va_end(list);
92 }
93
start_ptraced_child(void)94 static int start_ptraced_child(void)
95 {
96 int pid, n, status;
97
98 pid = fork();
99 if (pid == 0)
100 ptrace_child();
101 else if (pid < 0)
102 fatal_perror("start_ptraced_child : fork failed");
103
104 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
105 if (n < 0)
106 fatal_perror("check_ptrace : waitpid failed");
107 if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
108 fatal("check_ptrace : expected SIGSTOP, got status = %d",
109 status);
110
111 return pid;
112 }
113
114 /* When testing for SYSEMU support, if it is one of the broken versions, we
115 * must just avoid using sysemu, not panic, but only if SYSEMU features are
116 * broken.
117 * So only for SYSEMU features we test mustpanic, while normal host features
118 * must work anyway!
119 */
stop_ptraced_child(int pid,int exitcode,int mustexit)120 static int stop_ptraced_child(int pid, int exitcode, int mustexit)
121 {
122 int status, n, ret = 0;
123
124 if (ptrace(PTRACE_CONT, pid, 0, 0) < 0) {
125 perror("stop_ptraced_child : ptrace failed");
126 return -1;
127 }
128 CATCH_EINTR(n = waitpid(pid, &status, 0));
129 if (!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {
130 int exit_with = WEXITSTATUS(status);
131 if (exit_with == 2)
132 non_fatal("check_ptrace : child exited with status 2. "
133 "\nDisabling SYSEMU support.\n");
134 non_fatal("check_ptrace : child exited with exitcode %d, while "
135 "expecting %d; status 0x%x\n", exit_with,
136 exitcode, status);
137 if (mustexit)
138 exit(1);
139 ret = -1;
140 }
141
142 return ret;
143 }
144
145 /* Changed only during early boot */
146 int ptrace_faultinfo;
147 static int disable_ptrace_faultinfo;
148
149 int ptrace_ldt;
150 static int disable_ptrace_ldt;
151
152 int proc_mm;
153 static int disable_proc_mm;
154
155 int have_switch_mm;
156 static int disable_switch_mm;
157
158 int skas_needs_stub;
159
skas0_cmd_param(char * str,int * add)160 static int __init skas0_cmd_param(char *str, int* add)
161 {
162 disable_ptrace_faultinfo = 1;
163 disable_ptrace_ldt = 1;
164 disable_proc_mm = 1;
165 disable_switch_mm = 1;
166
167 return 0;
168 }
169
170 /* The two __uml_setup would conflict, without this stupid alias. */
171
172 static int __init mode_skas0_cmd_param(char *str, int* add)
173 __attribute__((alias("skas0_cmd_param")));
174
175 __uml_setup("skas0", skas0_cmd_param,
176 "skas0\n"
177 " Disables SKAS3 and SKAS4 usage, so that SKAS0 is used\n\n");
178
179 __uml_setup("mode=skas0", mode_skas0_cmd_param,
180 "mode=skas0\n"
181 " Disables SKAS3 and SKAS4 usage, so that SKAS0 is used.\n\n");
182
183 /* Changed only during early boot */
184 static int force_sysemu_disabled = 0;
185
nosysemu_cmd_param(char * str,int * add)186 static int __init nosysemu_cmd_param(char *str, int* add)
187 {
188 force_sysemu_disabled = 1;
189 return 0;
190 }
191
192 __uml_setup("nosysemu", nosysemu_cmd_param,
193 "nosysemu\n"
194 " Turns off syscall emulation patch for ptrace (SYSEMU) on.\n"
195 " SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n"
196 " behaviour of ptrace() and helps reducing host context switch rate.\n"
197 " To make it working, you need a kernel patch for your host, too.\n"
198 " See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n"
199 " information.\n\n");
200
check_sysemu(void)201 static void __init check_sysemu(void)
202 {
203 unsigned long regs[MAX_REG_NR];
204 int pid, n, status, count=0;
205
206 non_fatal("Checking syscall emulation patch for ptrace...");
207 sysemu_supported = 0;
208 pid = start_ptraced_child();
209
210 if (ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0)
211 goto fail;
212
213 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
214 if (n < 0)
215 fatal_perror("check_sysemu : wait failed");
216 if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
217 fatal("check_sysemu : expected SIGTRAP, got status = %d\n",
218 status);
219
220 if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
221 fatal_perror("check_sysemu : PTRACE_GETREGS failed");
222 if (PT_SYSCALL_NR(regs) != __NR_getpid) {
223 non_fatal("check_sysemu got system call number %d, "
224 "expected %d...", PT_SYSCALL_NR(regs), __NR_getpid);
225 goto fail;
226 }
227
228 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, os_getpid());
229 if (n < 0) {
230 non_fatal("check_sysemu : failed to modify system call "
231 "return");
232 goto fail;
233 }
234
235 if (stop_ptraced_child(pid, 0, 0) < 0)
236 goto fail_stopped;
237
238 sysemu_supported = 1;
239 non_fatal("OK\n");
240 set_using_sysemu(!force_sysemu_disabled);
241
242 non_fatal("Checking advanced syscall emulation patch for ptrace...");
243 pid = start_ptraced_child();
244
245 if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
246 (void *) PTRACE_O_TRACESYSGOOD) < 0))
247 fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed");
248
249 while (1) {
250 count++;
251 if (ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
252 goto fail;
253 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
254 if (n < 0)
255 fatal_perror("check_ptrace : wait failed");
256
257 if (WIFSTOPPED(status) &&
258 (WSTOPSIG(status) == (SIGTRAP|0x80))) {
259 if (!count) {
260 non_fatal("check_ptrace : SYSEMU_SINGLESTEP "
261 "doesn't singlestep");
262 goto fail;
263 }
264 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
265 os_getpid());
266 if (n < 0)
267 fatal_perror("check_sysemu : failed to modify "
268 "system call return");
269 break;
270 }
271 else if (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP))
272 count++;
273 else {
274 non_fatal("check_ptrace : expected SIGTRAP or "
275 "(SIGTRAP | 0x80), got status = %d\n",
276 status);
277 goto fail;
278 }
279 }
280 if (stop_ptraced_child(pid, 0, 0) < 0)
281 goto fail_stopped;
282
283 sysemu_supported = 2;
284 non_fatal("OK\n");
285
286 if (!force_sysemu_disabled)
287 set_using_sysemu(sysemu_supported);
288 return;
289
290 fail:
291 stop_ptraced_child(pid, 1, 0);
292 fail_stopped:
293 non_fatal("missing\n");
294 }
295
check_ptrace(void)296 static void __init check_ptrace(void)
297 {
298 int pid, syscall, n, status;
299
300 non_fatal("Checking that ptrace can change system call numbers...");
301 pid = start_ptraced_child();
302
303 if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
304 (void *) PTRACE_O_TRACESYSGOOD) < 0))
305 fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed");
306
307 while (1) {
308 if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
309 fatal_perror("check_ptrace : ptrace failed");
310
311 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
312 if (n < 0)
313 fatal_perror("check_ptrace : wait failed");
314
315 if (!WIFSTOPPED(status) ||
316 (WSTOPSIG(status) != (SIGTRAP | 0x80)))
317 fatal("check_ptrace : expected (SIGTRAP|0x80), "
318 "got status = %d", status);
319
320 syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET,
321 0);
322 if (syscall == __NR_getpid) {
323 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
324 __NR_getppid);
325 if (n < 0)
326 fatal_perror("check_ptrace : failed to modify "
327 "system call");
328 break;
329 }
330 }
331 stop_ptraced_child(pid, 0, 1);
332 non_fatal("OK\n");
333 check_sysemu();
334 }
335
336 extern void check_tmpexec(void);
337
check_coredump_limit(void)338 static void __init check_coredump_limit(void)
339 {
340 struct rlimit lim;
341 int err = getrlimit(RLIMIT_CORE, &lim);
342
343 if (err) {
344 perror("Getting core dump limit");
345 return;
346 }
347
348 printf("Core dump limits :\n\tsoft - ");
349 if (lim.rlim_cur == RLIM_INFINITY)
350 printf("NONE\n");
351 else printf("%lu\n", lim.rlim_cur);
352
353 printf("\thard - ");
354 if (lim.rlim_max == RLIM_INFINITY)
355 printf("NONE\n");
356 else printf("%lu\n", lim.rlim_max);
357 }
358
os_early_checks(void)359 void __init os_early_checks(void)
360 {
361 int pid;
362
363 /* Print out the core dump limits early */
364 check_coredump_limit();
365
366 check_ptrace();
367
368 /* Need to check this early because mmapping happens before the
369 * kernel is running.
370 */
371 check_tmpexec();
372
373 pid = start_ptraced_child();
374 if (init_registers(pid))
375 fatal("Failed to initialize default registers");
376 stop_ptraced_child(pid, 1, 1);
377 }
378
noprocmm_cmd_param(char * str,int * add)379 static int __init noprocmm_cmd_param(char *str, int* add)
380 {
381 disable_proc_mm = 1;
382 return 0;
383 }
384
385 __uml_setup("noprocmm", noprocmm_cmd_param,
386 "noprocmm\n"
387 " Turns off usage of /proc/mm, even if host supports it.\n"
388 " To support /proc/mm, the host needs to be patched using\n"
389 " the current skas3 patch.\n\n");
390
noptracefaultinfo_cmd_param(char * str,int * add)391 static int __init noptracefaultinfo_cmd_param(char *str, int* add)
392 {
393 disable_ptrace_faultinfo = 1;
394 return 0;
395 }
396
397 __uml_setup("noptracefaultinfo", noptracefaultinfo_cmd_param,
398 "noptracefaultinfo\n"
399 " Turns off usage of PTRACE_FAULTINFO, even if host supports\n"
400 " it. To support PTRACE_FAULTINFO, the host needs to be patched\n"
401 " using the current skas3 patch.\n\n");
402
noptraceldt_cmd_param(char * str,int * add)403 static int __init noptraceldt_cmd_param(char *str, int* add)
404 {
405 disable_ptrace_ldt = 1;
406 return 0;
407 }
408
409 __uml_setup("noptraceldt", noptraceldt_cmd_param,
410 "noptraceldt\n"
411 " Turns off usage of PTRACE_LDT, even if host supports it.\n"
412 " To support PTRACE_LDT, the host needs to be patched using\n"
413 " the current skas3 patch.\n\n");
414
check_skas3_ptrace_faultinfo(void)415 static inline void check_skas3_ptrace_faultinfo(void)
416 {
417 struct ptrace_faultinfo fi;
418 int pid, n;
419
420 non_fatal(" - PTRACE_FAULTINFO...");
421 pid = start_ptraced_child();
422
423 n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
424 if (n < 0) {
425 if (errno == EIO)
426 non_fatal("not found\n");
427 else
428 perror("not found");
429 } else if (disable_ptrace_faultinfo)
430 non_fatal("found but disabled on command line\n");
431 else {
432 ptrace_faultinfo = 1;
433 non_fatal("found\n");
434 }
435
436 stop_ptraced_child(pid, 1, 1);
437 }
438
check_skas3_ptrace_ldt(void)439 static inline void check_skas3_ptrace_ldt(void)
440 {
441 #ifdef PTRACE_LDT
442 int pid, n;
443 unsigned char ldtbuf[40];
444 struct ptrace_ldt ldt_op = (struct ptrace_ldt) {
445 .func = 2, /* read default ldt */
446 .ptr = ldtbuf,
447 .bytecount = sizeof(ldtbuf)};
448
449 non_fatal(" - PTRACE_LDT...");
450 pid = start_ptraced_child();
451
452 n = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op);
453 if (n < 0) {
454 if (errno == EIO)
455 non_fatal("not found\n");
456 else
457 perror("not found");
458 } else if (disable_ptrace_ldt)
459 non_fatal("found, but use is disabled\n");
460 else {
461 ptrace_ldt = 1;
462 non_fatal("found\n");
463 }
464
465 stop_ptraced_child(pid, 1, 1);
466 #endif
467 }
468
check_skas3_proc_mm(void)469 static inline void check_skas3_proc_mm(void)
470 {
471 non_fatal(" - /proc/mm...");
472 if (access("/proc/mm", W_OK) < 0)
473 perror("not found");
474 else if (disable_proc_mm)
475 non_fatal("found but disabled on command line\n");
476 else {
477 proc_mm = 1;
478 non_fatal("found\n");
479 }
480 }
481
can_do_skas(void)482 void can_do_skas(void)
483 {
484 non_fatal("Checking for the skas3 patch in the host:\n");
485
486 check_skas3_proc_mm();
487 check_skas3_ptrace_faultinfo();
488 check_skas3_ptrace_ldt();
489
490 if (!proc_mm || !ptrace_faultinfo || !ptrace_ldt)
491 skas_needs_stub = 1;
492 }
493
parse_iomem(char * str,int * add)494 int __init parse_iomem(char *str, int *add)
495 {
496 struct iomem_region *new;
497 struct stat64 buf;
498 char *file, *driver;
499 int fd, size;
500
501 driver = str;
502 file = strchr(str,',');
503 if (file == NULL) {
504 fprintf(stderr, "parse_iomem : failed to parse iomem\n");
505 goto out;
506 }
507 *file = '\0';
508 file++;
509 fd = open(file, O_RDWR, 0);
510 if (fd < 0) {
511 perror("parse_iomem - Couldn't open io file");
512 goto out;
513 }
514
515 if (fstat64(fd, &buf) < 0) {
516 perror("parse_iomem - cannot stat_fd file");
517 goto out_close;
518 }
519
520 new = malloc(sizeof(*new));
521 if (new == NULL) {
522 perror("Couldn't allocate iomem_region struct");
523 goto out_close;
524 }
525
526 size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1);
527
528 *new = ((struct iomem_region) { .next = iomem_regions,
529 .driver = driver,
530 .fd = fd,
531 .size = size,
532 .phys = 0,
533 .virt = 0 });
534 iomem_regions = new;
535 iomem_size += new->size + UM_KERN_PAGE_SIZE;
536
537 return 0;
538 out_close:
539 close(fd);
540 out:
541 return 1;
542 }
543