aboutsummaryrefslogtreecommitdiffstats
path: root/arch/um/os-Linux/start_up.c
blob: 5178eba9afa54fa779ab3af327e82259768d7fbf (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
/*
 * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
 * Licensed under the GPL
 */

#include <pty.h>
#include <stdio.h>
#include <stddef.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <sched.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <sys/mman.h>
#include <asm/unistd.h>
#include <asm/page.h>
#include <sys/types.h>
#include "user_util.h"
#include "kern_util.h"
#include "user.h"
#include "signal_kern.h"
#include "sysdep/ptrace.h"
#include "sysdep/sigcontext.h"
#include "irq_user.h"
#include "ptrace_user.h"
#include "mem_user.h"
#include "init.h"
#include "os.h"
#include "uml-config.h"
#include "choose-mode.h"
#include "mode.h"
#include "tempfile.h"
#include "kern_constants.h"

#ifdef UML_CONFIG_MODE_SKAS
#include "skas.h"
#include "skas_ptrace.h"
#include "registers.h"
#endif

static int ptrace_child(void *arg)
{
	int ret;
	int pid = os_getpid(), ppid = getppid();
	int sc_result;

	change_sig(SIGWINCH, 0);
	if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0){
		perror("ptrace");
		os_kill_process(pid, 0);
	}
	kill(pid, SIGSTOP);

	/*This syscall will be intercepted by the parent. Don't call more than
	 * once, please.*/
	sc_result = os_getpid();

	if (sc_result == pid)
		ret = 1; /*Nothing modified by the parent, we are running
			   normally.*/
	else if (sc_result == ppid)
		ret = 0; /*Expected in check_ptrace and check_sysemu when they
			   succeed in modifying the stack frame*/
	else
		ret = 2; /*Serious trouble! This could be caused by a bug in
			   host 2.6 SKAS3/2.6 patch before release -V6, together
			   with a bug in the UML code itself.*/
	_exit(ret);
}

static void fatal_perror(char *str)
{
	perror(str);
	exit(1);
}

static void fatal(char *fmt, ...)
{
	va_list list;

	va_start(list, fmt);
	vprintf(fmt, list);
	va_end(list);
	fflush(stdout);

	exit(1);
}

static void non_fatal(char *fmt, ...)
{
	va_list list;

	va_start(list, fmt);
	vprintf(fmt, list);
	va_end(list);
	fflush(stdout);
}

static int start_ptraced_child(void **stack_out)
{
	void *stack;
	unsigned long sp;
	int pid, n, status;

	stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,
		     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
	if(stack == MAP_FAILED)
		fatal_perror("check_ptrace : mmap failed");
	sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *);
	pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL);
	if(pid < 0)
		fatal_perror("start_ptraced_child : clone failed");
	CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
	if(n < 0)
		fatal_perror("check_ptrace : clone failed");
	if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
		fatal("check_ptrace : expected SIGSTOP, got status = %d",
		      status);

	*stack_out = stack;
	return pid;
}

/* When testing for SYSEMU support, if it is one of the broken versions, we
 * must just avoid using sysemu, not panic, but only if SYSEMU features are
 * broken.
 * So only for SYSEMU features we test mustpanic, while normal host features
 * must work anyway!
 */
static int stop_ptraced_child(int pid, void *stack, int exitcode,
			      int mustexit)
{
	int status, n, ret = 0;

	if(ptrace(PTRACE_CONT, pid, 0, 0) < 0)
		fatal_perror("stop_ptraced_child : ptrace failed");
	CATCH_EINTR(n = waitpid(pid, &status, 0));
	if(!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {
		int exit_with = WEXITSTATUS(status);
		if (exit_with == 2)
			non_fatal("check_ptrace : child exited with status 2. "
				  "Serious trouble happening! Try updating "
				  "your host skas patch!\nDisabling SYSEMU "
				  "support.");
		non_fatal("check_ptrace : child exited with exitcode %d, while "
			  "expecting %d; status 0x%x\n", exit_with,
			  exitcode, status);
		if (mustexit)
			exit(1);
		ret = -1;
	}

	if(munmap(stack, PAGE_SIZE) < 0)
		fatal_perror("check_ptrace : munmap failed");
	return ret;
}

/* Changed only during early boot */
int ptrace_faultinfo = 1;
int ptrace_ldt = 1;
int proc_mm = 1;
int skas_needs_stub = 0;

static int __init skas0_cmd_param(char *str, int* add)
{
	ptrace_faultinfo = proc_mm = 0;
	return 0;
}

/* The two __uml_setup would conflict, without this stupid alias. */

static int __init mode_skas0_cmd_param(char *str, int* add)
	__attribute__((alias("skas0_cmd_param")));

__uml_setup("skas0", skas0_cmd_param,
		"skas0\n"
		"    Disables SKAS3 usage, so that SKAS0 is used, unless \n"
	        "    you specify mode=tt.\n\n");

__uml_setup("mode=skas0", mode_skas0_cmd_param,
		"mode=skas0\n"
		"    Disables SKAS3 usage, so that SKAS0 is used, unless you \n"
		"    specify mode=tt. Note that this was recently added - on \n"
		"    older kernels you must use simply \"skas0\".\n\n");

/* Changed only during early boot */
static int force_sysemu_disabled = 0;

static int __init nosysemu_cmd_param(char *str, int* add)
{
	force_sysemu_disabled = 1;
	return 0;
}

__uml_setup("nosysemu", nosysemu_cmd_param,
"nosysemu\n"
"    Turns off syscall emulation patch for ptrace (SYSEMU) on.\n"
"    SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n"
"    behaviour of ptrace() and helps reducing host context switch rate.\n"
"    To make it working, you need a kernel patch for your host, too.\n"
"    See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n"
"    information.\n\n");

static void __init check_sysemu(void)
{
	void *stack;
	int pid, n, status, count=0;

	non_fatal("Checking syscall emulation patch for ptrace...");
	sysemu_supported = 0;
	pid = start_ptraced_child(&stack);

	if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0)
		goto fail;

	CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
	if (n < 0)
		fatal_perror("check_sysemu : wait failed");
	if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
		fatal("check_sysemu : expected SIGTRAP, got status = %d",
		      status);

	n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
		   os_getpid());
	if(n < 0)
		fatal_perror("check_sysemu : failed to modify system call "
			     "return");

	if (stop_ptraced_child(pid, stack, 0, 0) < 0)
		goto fail_stopped;

	sysemu_supported = 1;
	non_fatal("OK\n");
	set_using_sysemu(!force_sysemu_disabled);

	non_fatal("Checking advanced syscall emulation patch for ptrace...");
	pid = start_ptraced_child(&stack);

	if((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
		   (void *) PTRACE_O_TRACESYSGOOD) < 0))
		fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed");

	while(1){
		count++;
		if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
			goto fail;
		CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
		if(n < 0)
			fatal_perror("check_ptrace : wait failed");

		if(WIFSTOPPED(status) && (WSTOPSIG(status) == (SIGTRAP|0x80))){
			if (!count)
				fatal("check_ptrace : SYSEMU_SINGLESTEP "
				      "doesn't singlestep");
			n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
				   os_getpid());
			if(n < 0)
				fatal_perror("check_sysemu : failed to modify "
					     "system call return");
			break;
		}
		else if(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP))
			count++;
		else
			fatal("check_ptrace : expected SIGTRAP or "
			      "(SIGTRAP | 0x80), got status = %d", status);
	}
	if (stop_ptraced_child(pid, stack, 0, 0) < 0)
		goto fail_stopped;

	sysemu_supported = 2;
	non_fatal("OK\n");

	if ( !force_sysemu_disabled )
		set_using_sysemu(sysemu_supported);
	return;

fail:
	stop_ptraced_child(pid, stack, 1, 0);
fail_stopped:
	non_fatal("missing\n");
}

static void __init check_ptrace(void)
{
	void *stack;
	int pid, syscall, n, status;

	non_fatal("Checking that ptrace can change system call numbers...");
	pid = start_ptraced_child(&stack);

	if((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
		   (void *) PTRACE_O_TRACESYSGOOD) < 0))
		fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed");

	while(1){
		if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
			fatal_perror("check_ptrace : ptrace failed");

		CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
		if(n < 0)
			fatal_perror("check_ptrace : wait failed");

		if(!WIFSTOPPED(status) ||
		   (WSTOPSIG(status) != (SIGTRAP | 0x80)))
			fatal("check_ptrace : expected (SIGTRAP|0x80), "
			       "got status = %d", status);

		syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET,
				 0);
		if(syscall == __NR_getpid){
			n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
				   __NR_getppid);
			if(n < 0)
				fatal_perror("check_ptrace : failed to modify "
					     "system call");
			break;
		}
	}
	stop_ptraced_child(pid, stack, 0, 1);
	non_fatal("OK\n");
	check_sysemu();
}

extern void check_tmpexec(void);

void os_early_checks(void)
{
	check_ptrace();

	/* Need to check this early because mmapping happens before the
	 * kernel is running.
	 */
	check_tmpexec();
}

static int __init noprocmm_cmd_param(char *str, int* add)
{
	proc_mm = 0;
	return 0;
}

__uml_setup("noprocmm", noprocmm_cmd_param,
"noprocmm\n"
"    Turns off usage of /proc/mm, even if host supports it.\n"
"    To support /proc/mm, the host needs to be patched using\n"
"    the current skas3 patch.\n\n");

static int __init noptracefaultinfo_cmd_param(char *str, int* add)
{
	ptrace_faultinfo = 0;
	return 0;
}

__uml_setup("noptracefaultinfo", noptracefaultinfo_cmd_param,
"noptracefaultinfo\n"
"    Turns off usage of PTRACE_FAULTINFO, even if host supports\n"
"    it. To support PTRACE_FAULTINFO, the host needs to be patched\n"
"    using the current skas3 patch.\n\n");

static int __init noptraceldt_cmd_param(char *str, int* add)
{
	ptrace_ldt = 0;
	return 0;
}

__uml_setup("noptraceldt", noptraceldt_cmd_param,
"noptraceldt\n"
"    Turns off usage of PTRACE_LDT, even if host supports it.\n"
"    To support PTRACE_LDT, the host needs to be patched using\n"
"    the current skas3 patch.\n\n");

#ifdef UML_CONFIG_MODE_SKAS
static inline void check_skas3_ptrace_faultinfo(void)
{
	struct ptrace_faultinfo fi;
	void *stack;
	int pid, n;

	non_fatal("  - PTRACE_FAULTINFO...");
	pid = start_ptraced_child(&stack);

	n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
	if (n < 0) {
		ptrace_faultinfo = 0;
		if(errno == EIO)
			non_fatal("not found\n");
		else
			perror("not found");
	}
	else {
		if (!ptrace_faultinfo)
			non_fatal("found but disabled on command line\n");
		else
			non_fatal("found\n");
	}

	init_registers(pid);
	stop_ptraced_child(pid, stack, 1, 1);
}

static inline void check_skas3_ptrace_ldt(void)
{
#ifdef PTRACE_LDT
	void *stack;
	int pid, n;
	unsigned char ldtbuf[40];
	struct ptrace_ldt ldt_op = (struct ptrace_ldt) {
		.func = 2, /* read default ldt */
		.ptr = ldtbuf,
		.bytecount = sizeof(ldtbuf)};

	non_fatal("  - PTRACE_LDT...");
	pid = start_ptraced_child(&stack);

	n = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op);
	if (n < 0) {
		if(errno == EIO)
			non_fatal("not found\n");
		else {
			perror("not found");
		}
		ptrace_ldt = 0;
	}
	else {
		if(ptrace_ldt)
			non_fatal("found\n");
		else
			non_fatal("found, but use is disabled\n");
	}

	stop_ptraced_child(pid, stack, 1, 1);
#else
	/* PTRACE_LDT might be disabled via cmdline option.
	 * We want to override this, else we might use the stub
	 * without real need
	 */
	ptrace_ldt = 1;
#endif
}

static inline void check_skas3_proc_mm(void)
{
	non_fatal("  - /proc/mm...");
	if (access("/proc/mm", W_OK) < 0) {
		proc_mm = 0;
		perror("not found");
	}
	else {
		if (!proc_mm)
			non_fatal("found but disabled on command line\n");
		else
			non_fatal("found\n");
	}
}

int can_do_skas(void)
{
	non_fatal("Checking for the skas3 patch in the host:\n");

	check_skas3_proc_mm();
	check_skas3_ptrace_faultinfo();
	check_skas3_ptrace_ldt();

	if(!proc_mm || !ptrace_faultinfo || !ptrace_ldt)
		skas_needs_stub = 1;

	return 1;
}
#else
int can_do_skas(void)
{
	return 0;
}
#endif

int __init parse_iomem(char *str, int *add)
{
	struct iomem_region *new;
	struct stat64 buf;
	char *file, *driver;
	int fd, size;

	driver = str;
	file = strchr(str,',');
	if(file == NULL){
		printf("parse_iomem : failed to parse iomem\n");
		goto out;
	}
	*file = '\0';
	file++;
	fd = open(file, O_RDWR, 0);
	if(fd < 0){
		os_print_error(fd, "parse_iomem - Couldn't open io file");
		goto out;
	}

	if(fstat64(fd, &buf) < 0){
		perror("parse_iomem - cannot stat_fd file");
		goto out_close;
	}

	new = malloc(sizeof(*new));
	if(new == NULL){
		perror("Couldn't allocate iomem_region struct");
		goto out_close;
	}

	size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1);

	*new = ((struct iomem_region) { .next		= iomem_regions,
					.driver		= driver,
					.fd		= fd,
					.size		= size,
					.phys		= 0,
					.virt		= 0 });
	iomem_regions = new;
	iomem_size += new->size + UM_KERN_PAGE_SIZE;

	return 0;
 out_close:
	close(fd);
 out:
	return 1;
}


/* Changed during early boot */
int pty_output_sigio = 0;
int pty_close_sigio = 0;

/* Used as a flag during SIGIO testing early in boot */
static volatile int got_sigio = 0;

static void __init handler(int sig)
{
	got_sigio = 1;
}

struct openpty_arg {
	int master;
	int slave;
	int err;
};

static void openpty_cb(void *arg)
{
	struct openpty_arg *info = arg;

	info->err = 0;
	if(openpty(&info->master, &info->slave, NULL, NULL, NULL))
		info->err = -errno;
}

static int async_pty(int master, int slave)
{
	int flags;

	flags = fcntl(master, F_GETFL);
	if(flags < 0)
		return -errno;

	if((fcntl(master, F_SETFL, flags | O_NONBLOCK | O_ASYNC) < 0) ||
	   (fcntl(master, F_SETOWN, os_getpid()) < 0))
		return -errno;

	if((fcntl(slave, F_SETFL, flags | O_NONBLOCK) < 0))
		return -errno;

	return(0);
}

static void __init check_one_sigio(void (*proc)(int, int))
{
	struct sigaction old, new;
	struct openpty_arg pty = { .master = -1, .slave = -1 };
	int master, slave, err;

	initial_thread_cb(openpty_cb, &pty);
	if(pty.err){
		printk("openpty failed, errno = %d\n", -pty.err);
		return;
	}

	master = pty.master;
	slave = pty.slave;

	if((master == -1) || (slave == -1)){
		printk("openpty failed to allocate a pty\n");
		return;
	}

	/* Not now, but complain so we now where we failed. */
	err = raw(master);
	if (err < 0)
		panic("check_sigio : __raw failed, errno = %d\n", -err);

	err = async_pty(master, slave);
	if(err < 0)
		panic("tty_fds : sigio_async failed, err = %d\n", -err);

	if(sigaction(SIGIO, NULL, &old) < 0)
		panic("check_sigio : sigaction 1 failed, errno = %d\n", errno);
	new = old;
	new.sa_handler = handler;
	if(sigaction(SIGIO, &new, NULL) < 0)
		panic("check_sigio : sigaction 2 failed, errno = %d\n", errno);

	got_sigio = 0;
	(*proc)(master, slave);

	close(master);
	close(slave);

	if(sigaction(SIGIO, &old, NULL) < 0)
		panic("check_sigio : sigaction 3 failed, errno = %d\n", errno);
}

static void tty_output(int master, int slave)
{
	int n;
	char buf[512];

	printk("Checking that host ptys support output SIGIO...");

	memset(buf, 0, sizeof(buf));

	while(os_write_file(master, buf, sizeof(buf)) > 0) ;
	if(errno != EAGAIN)
		panic("check_sigio : write failed, errno = %d\n", errno);
	while(((n = os_read_file(slave, buf, sizeof(buf))) > 0) && !got_sigio) ;

	if(got_sigio){
		printk("Yes\n");
		pty_output_sigio = 1;
	}
	else if(n == -EAGAIN) printk("No, enabling workaround\n");
	else panic("check_sigio : read failed, err = %d\n", n);
}

static void tty_close(int master, int slave)
{
	printk("Checking that host ptys support SIGIO on close...");

	close(slave);
	if(got_sigio){
		printk("Yes\n");
		pty_close_sigio = 1;
	}
	else printk("No, enabling workaround\n");
}

void __init check_sigio(void)
{
	if((os_access("/dev/ptmx", OS_ACC_R_OK) < 0) &&
	   (os_access("/dev/ptyp0", OS_ACC_R_OK) < 0)){
		printk("No pseudo-terminals available - skipping pty SIGIO "
		       "check\n");
		return;
	}
	check_one_sigio(tty_output);
	check_one_sigio(tty_close);
}

void os_check_bugs(void)
{
	check_ptrace();
	check_sigio();
}