1/*
2 * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
3 * Licensed under the GPL
4 */
5
6#include <pty.h>
7#include <stdio.h>
8#include <stddef.h>
9#include <stdarg.h>
10#include <stdlib.h>
11#include <string.h>
12#include <unistd.h>
13#include <signal.h>
14#include <sched.h>
15#include <fcntl.h>
16#include <errno.h>
17#include <sys/time.h>
18#include <sys/wait.h>
19#include <sys/mman.h>
20#include <sys/resource.h>
21#include <asm/unistd.h>
22#include <asm/page.h>
23#include <sys/types.h>
24#include "kern_util.h"
25#include "user.h"
26#include "signal_kern.h"
27#include "sysdep/ptrace.h"
28#include "sysdep/sigcontext.h"
29#include "irq_user.h"
30#include "ptrace_user.h"
31#include "mem_user.h"
32#include "init.h"
33#include "os.h"
34#include "uml-config.h"
35#include "choose-mode.h"
36#include "mode.h"
37#include "tempfile.h"
38#include "kern_constants.h"
39
40#ifdef UML_CONFIG_MODE_SKAS
41#include "skas.h"
42#include "skas_ptrace.h"
43#include "registers.h"
44#endif
45
46static int ptrace_child(void *arg)
47{
48	int ret;
49	int pid = os_getpid(), ppid = getppid();
50	int sc_result;
51
52	change_sig(SIGWINCH, 0);
53	if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0){
54		perror("ptrace");
55		os_kill_process(pid, 0);
56	}
57	kill(pid, SIGSTOP);
58
59	/*This syscall will be intercepted by the parent. Don't call more than
60	 * once, please.*/
61	sc_result = os_getpid();
62
63	if (sc_result == pid)
64		ret = 1; /*Nothing modified by the parent, we are running
65			   normally.*/
66	else if (sc_result == ppid)
67		ret = 0; /*Expected in check_ptrace and check_sysemu when they
68			   succeed in modifying the stack frame*/
69	else
70		ret = 2; /*Serious trouble! This could be caused by a bug in
71			   host 2.6 SKAS3/2.6 patch before release -V6, together
72			   with a bug in the UML code itself.*/
73	_exit(ret);
74}
75
76static void fatal_perror(char *str)
77{
78	perror(str);
79	exit(1);
80}
81
82static void fatal(char *fmt, ...)
83{
84	va_list list;
85
86	va_start(list, fmt);
87	vprintf(fmt, list);
88	va_end(list);
89	fflush(stdout);
90
91	exit(1);
92}
93
94static void non_fatal(char *fmt, ...)
95{
96	va_list list;
97
98	va_start(list, fmt);
99	vprintf(fmt, list);
100	va_end(list);
101	fflush(stdout);
102}
103
104static int start_ptraced_child(void **stack_out)
105{
106	void *stack;
107	unsigned long sp;
108	int pid, n, status;
109
110	stack = mmap(NULL, UM_KERN_PAGE_SIZE,
111		     PROT_READ | PROT_WRITE | PROT_EXEC,
112		     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
113	if(stack == MAP_FAILED)
114		fatal_perror("check_ptrace : mmap failed");
115	sp = (unsigned long) stack + UM_KERN_PAGE_SIZE - sizeof(void *);
116	pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL);
117	if(pid < 0)
118		fatal_perror("start_ptraced_child : clone failed");
119	CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
120	if(n < 0)
121		fatal_perror("check_ptrace : clone failed");
122	if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
123		fatal("check_ptrace : expected SIGSTOP, got status = %d",
124		      status);
125
126	*stack_out = stack;
127	return pid;
128}
129
130/* When testing for SYSEMU support, if it is one of the broken versions, we
131 * must just avoid using sysemu, not panic, but only if SYSEMU features are
132 * broken.
133 * So only for SYSEMU features we test mustpanic, while normal host features
134 * must work anyway!
135 */
136static int stop_ptraced_child(int pid, void *stack, int exitcode,
137			      int mustexit)
138{
139	int status, n, ret = 0;
140
141	if(ptrace(PTRACE_CONT, pid, 0, 0) < 0)
142		fatal_perror("stop_ptraced_child : ptrace failed");
143	CATCH_EINTR(n = waitpid(pid, &status, 0));
144	if(!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {
145		int exit_with = WEXITSTATUS(status);
146		if (exit_with == 2)
147			non_fatal("check_ptrace : child exited with status 2. "
148				  "\nDisabling SYSEMU support.\n");
149		non_fatal("check_ptrace : child exited with exitcode %d, while "
150			  "expecting %d; status 0x%x\n", exit_with,
151			  exitcode, status);
152		if (mustexit)
153			exit(1);
154		ret = -1;
155	}
156
157	if(munmap(stack, UM_KERN_PAGE_SIZE) < 0)
158		fatal_perror("check_ptrace : munmap failed");
159	return ret;
160}
161
162/* Changed only during early boot */
163int ptrace_faultinfo = 1;
164int ptrace_ldt = 1;
165int proc_mm = 1;
166int skas_needs_stub = 0;
167
168static int __init skas0_cmd_param(char *str, int* add)
169{
170	ptrace_faultinfo = proc_mm = 0;
171	return 0;
172}
173
174/* The two __uml_setup would conflict, without this stupid alias. */
175
176static int __init mode_skas0_cmd_param(char *str, int* add)
177	__attribute__((alias("skas0_cmd_param")));
178
179__uml_setup("skas0", skas0_cmd_param,
180		"skas0\n"
181		"    Disables SKAS3 usage, so that SKAS0 is used, unless \n"
182	        "    you specify mode=tt.\n\n");
183
184__uml_setup("mode=skas0", mode_skas0_cmd_param,
185		"mode=skas0\n"
186		"    Disables SKAS3 usage, so that SKAS0 is used, unless you \n"
187		"    specify mode=tt. Note that this was recently added - on \n"
188		"    older kernels you must use simply \"skas0\".\n\n");
189
190/* Changed only during early boot */
191static int force_sysemu_disabled = 0;
192
193static int __init nosysemu_cmd_param(char *str, int* add)
194{
195	force_sysemu_disabled = 1;
196	return 0;
197}
198
199__uml_setup("nosysemu", nosysemu_cmd_param,
200"nosysemu\n"
201"    Turns off syscall emulation patch for ptrace (SYSEMU) on.\n"
202"    SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n"
203"    behaviour of ptrace() and helps reducing host context switch rate.\n"
204"    To make it working, you need a kernel patch for your host, too.\n"
205"    See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n"
206"    information.\n\n");
207
208static void __init check_sysemu(void)
209{
210	void *stack;
211	unsigned long regs[MAX_REG_NR];
212	int pid, n, status, count=0;
213
214	non_fatal("Checking syscall emulation patch for ptrace...");
215	sysemu_supported = 0;
216	pid = start_ptraced_child(&stack);
217
218	if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0)
219		goto fail;
220
221	CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
222	if (n < 0)
223		fatal_perror("check_sysemu : wait failed");
224	if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
225		fatal("check_sysemu : expected SIGTRAP, got status = %d",
226		      status);
227
228	if(ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
229		fatal_perror("check_sysemu : PTRACE_GETREGS failed");
230	if(PT_SYSCALL_NR(regs) != __NR_getpid){
231		non_fatal("check_sysemu got system call number %d, "
232			  "expected %d...", PT_SYSCALL_NR(regs), __NR_getpid);
233		goto fail;
234	}
235
236	n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, os_getpid());
237	if(n < 0){
238		non_fatal("check_sysemu : failed to modify system call "
239			  "return");
240		goto fail;
241	}
242
243	if (stop_ptraced_child(pid, stack, 0, 0) < 0)
244		goto fail_stopped;
245
246	sysemu_supported = 1;
247	non_fatal("OK\n");
248	set_using_sysemu(!force_sysemu_disabled);
249
250	non_fatal("Checking advanced syscall emulation patch for ptrace...");
251	pid = start_ptraced_child(&stack);
252
253	if((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
254		   (void *) PTRACE_O_TRACESYSGOOD) < 0))
255		fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed");
256
257	while(1){
258		count++;
259		if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
260			goto fail;
261		CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
262		if(n < 0)
263			fatal_perror("check_ptrace : wait failed");
264
265		if(WIFSTOPPED(status) && (WSTOPSIG(status) == (SIGTRAP|0x80))){
266			if (!count)
267				fatal("check_ptrace : SYSEMU_SINGLESTEP "
268				      "doesn't singlestep");
269			n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
270				   os_getpid());
271			if(n < 0)
272				fatal_perror("check_sysemu : failed to modify "
273					     "system call return");
274			break;
275		}
276		else if(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP))
277			count++;
278		else
279			fatal("check_ptrace : expected SIGTRAP or "
280			      "(SIGTRAP | 0x80), got status = %d", status);
281	}
282	if (stop_ptraced_child(pid, stack, 0, 0) < 0)
283		goto fail_stopped;
284
285	sysemu_supported = 2;
286	non_fatal("OK\n");
287
288	if ( !force_sysemu_disabled )
289		set_using_sysemu(sysemu_supported);
290	return;
291
292fail:
293	stop_ptraced_child(pid, stack, 1, 0);
294fail_stopped:
295	non_fatal("missing\n");
296}
297
298static void __init check_ptrace(void)
299{
300	void *stack;
301	int pid, syscall, n, status;
302
303	non_fatal("Checking that ptrace can change system call numbers...");
304	pid = start_ptraced_child(&stack);
305
306	if((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
307		   (void *) PTRACE_O_TRACESYSGOOD) < 0))
308		fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed");
309
310	while(1){
311		if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
312			fatal_perror("check_ptrace : ptrace failed");
313
314		CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
315		if(n < 0)
316			fatal_perror("check_ptrace : wait failed");
317
318		if(!WIFSTOPPED(status) ||
319		   (WSTOPSIG(status) != (SIGTRAP | 0x80)))
320			fatal("check_ptrace : expected (SIGTRAP|0x80), "
321			       "got status = %d", status);
322
323		syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET,
324				 0);
325		if(syscall == __NR_getpid){
326			n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
327				   __NR_getppid);
328			if(n < 0)
329				fatal_perror("check_ptrace : failed to modify "
330					     "system call");
331			break;
332		}
333	}
334	stop_ptraced_child(pid, stack, 0, 1);
335	non_fatal("OK\n");
336	check_sysemu();
337}
338
339extern void check_tmpexec(void);
340
341static void __init check_coredump_limit(void)
342{
343	struct rlimit lim;
344	int err = getrlimit(RLIMIT_CORE, &lim);
345
346	if(err){
347		perror("Getting core dump limit");
348		return;
349	}
350
351	printf("Core dump limits :\n\tsoft - ");
352	if(lim.rlim_cur == RLIM_INFINITY)
353		printf("NONE\n");
354	else printf("%lu\n", lim.rlim_cur);
355
356	printf("\thard - ");
357	if(lim.rlim_max == RLIM_INFINITY)
358		printf("NONE\n");
359	else printf("%lu\n", lim.rlim_max);
360}
361
362void __init os_early_checks(void)
363{
364	/* Print out the core dump limits early */
365	check_coredump_limit();
366
367	check_ptrace();
368
369	/* Need to check this early because mmapping happens before the
370	 * kernel is running.
371	 */
372	check_tmpexec();
373}
374
375static int __init noprocmm_cmd_param(char *str, int* add)
376{
377	proc_mm = 0;
378	return 0;
379}
380
381__uml_setup("noprocmm", noprocmm_cmd_param,
382"noprocmm\n"
383"    Turns off usage of /proc/mm, even if host supports it.\n"
384"    To support /proc/mm, the host needs to be patched using\n"
385"    the current skas3 patch.\n\n");
386
387static int __init noptracefaultinfo_cmd_param(char *str, int* add)
388{
389	ptrace_faultinfo = 0;
390	return 0;
391}
392
393__uml_setup("noptracefaultinfo", noptracefaultinfo_cmd_param,
394"noptracefaultinfo\n"
395"    Turns off usage of PTRACE_FAULTINFO, even if host supports\n"
396"    it. To support PTRACE_FAULTINFO, the host needs to be patched\n"
397"    using the current skas3 patch.\n\n");
398
399static int __init noptraceldt_cmd_param(char *str, int* add)
400{
401	ptrace_ldt = 0;
402	return 0;
403}
404
405__uml_setup("noptraceldt", noptraceldt_cmd_param,
406"noptraceldt\n"
407"    Turns off usage of PTRACE_LDT, even if host supports it.\n"
408"    To support PTRACE_LDT, the host needs to be patched using\n"
409"    the current skas3 patch.\n\n");
410
411#ifdef UML_CONFIG_MODE_SKAS
412static inline void check_skas3_ptrace_faultinfo(void)
413{
414	struct ptrace_faultinfo fi;
415	void *stack;
416	int pid, n;
417
418	non_fatal("  - PTRACE_FAULTINFO...");
419	pid = start_ptraced_child(&stack);
420
421	n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
422	if (n < 0) {
423		ptrace_faultinfo = 0;
424		if(errno == EIO)
425			non_fatal("not found\n");
426		else
427			perror("not found");
428	}
429	else {
430		if (!ptrace_faultinfo)
431			non_fatal("found but disabled on command line\n");
432		else
433			non_fatal("found\n");
434	}
435
436	init_registers(pid);
437	stop_ptraced_child(pid, stack, 1, 1);
438}
439
440static inline void check_skas3_ptrace_ldt(void)
441{
442#ifdef PTRACE_LDT
443	void *stack;
444	int pid, n;
445	unsigned char ldtbuf[40];
446	struct ptrace_ldt ldt_op = (struct ptrace_ldt) {
447		.func = 2, /* read default ldt */
448		.ptr = ldtbuf,
449		.bytecount = sizeof(ldtbuf)};
450
451	non_fatal("  - PTRACE_LDT...");
452	pid = start_ptraced_child(&stack);
453
454	n = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op);
455	if (n < 0) {
456		if(errno == EIO)
457			non_fatal("not found\n");
458		else {
459			perror("not found");
460		}
461		ptrace_ldt = 0;
462	}
463	else {
464		if(ptrace_ldt)
465			non_fatal("found\n");
466		else
467			non_fatal("found, but use is disabled\n");
468	}
469
470	stop_ptraced_child(pid, stack, 1, 1);
471#else
472	/* PTRACE_LDT might be disabled via cmdline option.
473	 * We want to override this, else we might use the stub
474	 * without real need
475	 */
476	ptrace_ldt = 1;
477#endif
478}
479
480static inline void check_skas3_proc_mm(void)
481{
482	non_fatal("  - /proc/mm...");
483	if (access("/proc/mm", W_OK) < 0) {
484		proc_mm = 0;
485		perror("not found");
486	}
487	else {
488		if (!proc_mm)
489			non_fatal("found but disabled on command line\n");
490		else
491			non_fatal("found\n");
492	}
493}
494
495int can_do_skas(void)
496{
497	non_fatal("Checking for the skas3 patch in the host:\n");
498
499	check_skas3_proc_mm();
500	check_skas3_ptrace_faultinfo();
501	check_skas3_ptrace_ldt();
502
503	if(!proc_mm || !ptrace_faultinfo || !ptrace_ldt)
504		skas_needs_stub = 1;
505
506	return 1;
507}
508#else
509int can_do_skas(void)
510{
511	return 0;
512}
513#endif
514
515int __init parse_iomem(char *str, int *add)
516{
517	struct iomem_region *new;
518	struct stat64 buf;
519	char *file, *driver;
520	int fd, size;
521
522	driver = str;
523	file = strchr(str,',');
524	if(file == NULL){
525		printf("parse_iomem : failed to parse iomem\n");
526		goto out;
527	}
528	*file = '\0';
529	file++;
530	fd = open(file, O_RDWR, 0);
531	if(fd < 0){
532		os_print_error(fd, "parse_iomem - Couldn't open io file");
533		goto out;
534	}
535
536	if(fstat64(fd, &buf) < 0){
537		perror("parse_iomem - cannot stat_fd file");
538		goto out_close;
539	}
540
541	new = malloc(sizeof(*new));
542	if(new == NULL){
543		perror("Couldn't allocate iomem_region struct");
544		goto out_close;
545	}
546
547	size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1);
548
549	*new = ((struct iomem_region) { .next		= iomem_regions,
550					.driver		= driver,
551					.fd		= fd,
552					.size		= size,
553					.phys		= 0,
554					.virt		= 0 });
555	iomem_regions = new;
556	iomem_size += new->size + UM_KERN_PAGE_SIZE;
557
558	return 0;
559 out_close:
560	close(fd);
561 out:
562	return 1;
563}
564