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