1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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 <sys/time.h>
19#include <sys/resource.h>
20#include <asm/unistd.h>
21#include <init.h>
22#include <os.h>
23#include <mem_user.h>
24#include <ptrace_user.h>
25#include <registers.h>
26#include <skas.h>
27
28static void ptrace_child(void)
29{
30	int ret;
31	/* Calling os_getpid because some libcs cached getpid incorrectly */
32	int pid = os_getpid(), ppid = getppid();
33	int sc_result;
34
35	if (change_sig(SIGWINCH, 0) < 0 ||
36	    ptrace(PTRACE_TRACEME, 0, 0, 0) < 0) {
37		perror("ptrace");
38		kill(pid, SIGKILL);
39	}
40	kill(pid, SIGSTOP);
41
42	/*
43	 * This syscall will be intercepted by the parent. Don't call more than
44	 * once, please.
45	 */
46	sc_result = os_getpid();
47
48	if (sc_result == pid)
49		/* Nothing modified by the parent, we are running normally. */
50		ret = 1;
51	else if (sc_result == ppid)
52		/*
53		 * Expected in check_ptrace and check_sysemu when they succeed
54		 * in modifying the stack frame
55		 */
56		ret = 0;
57	else
58		/* Serious trouble! This could be caused by a bug in host 2.6
59		 * SKAS3/2.6 patch before release -V6, together with a bug in
60		 * the UML code itself.
61		 */
62		ret = 2;
63
64	exit(ret);
65}
66
67static void fatal_perror(const char *str)
68{
69	perror(str);
70	exit(1);
71}
72
73static void fatal(char *fmt, ...)
74{
75	va_list list;
76
77	va_start(list, fmt);
78	vfprintf(stderr, fmt, list);
79	va_end(list);
80
81	exit(1);
82}
83
84static void non_fatal(char *fmt, ...)
85{
86	va_list list;
87
88	va_start(list, fmt);
89	vfprintf(stderr, fmt, list);
90	va_end(list);
91}
92
93static int start_ptraced_child(void)
94{
95	int pid, n, status;
96
97	fflush(stdout);
98
99	pid = fork();
100	if (pid == 0)
101		ptrace_child();
102	else if (pid < 0)
103		fatal_perror("start_ptraced_child : fork failed");
104
105	CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
106	if (n < 0)
107		fatal_perror("check_ptrace : waitpid failed");
108	if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
109		fatal("check_ptrace : expected SIGSTOP, got status = %d",
110		      status);
111
112	return pid;
113}
114
115static void stop_ptraced_child(int pid, int exitcode)
116{
117	int status, n;
118
119	if (ptrace(PTRACE_CONT, pid, 0, 0) < 0)
120		fatal_perror("stop_ptraced_child : ptrace failed");
121
122	CATCH_EINTR(n = waitpid(pid, &status, 0));
123	if (!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {
124		int exit_with = WEXITSTATUS(status);
125		fatal("stop_ptraced_child : child exited with exitcode %d, "
126		      "while expecting %d; status 0x%x\n", exit_with,
127		      exitcode, status);
128	}
129}
130
131static void __init check_sysemu(void)
132{
133	int pid, n, status, count=0;
134
135	os_info("Checking syscall emulation for ptrace...");
136	pid = start_ptraced_child();
137
138	if ((ptrace(PTRACE_SETOPTIONS, pid, 0,
139		   (void *) PTRACE_O_TRACESYSGOOD) < 0))
140		fatal_perror("check_sysemu: PTRACE_SETOPTIONS failed");
141
142	while (1) {
143		count++;
144		if (ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
145			goto fail;
146		CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
147		if (n < 0)
148			fatal_perror("check_sysemu: wait failed");
149
150		if (WIFSTOPPED(status) &&
151		    (WSTOPSIG(status) == (SIGTRAP|0x80))) {
152			if (!count) {
153				non_fatal("check_sysemu: SYSEMU_SINGLESTEP "
154					  "doesn't singlestep");
155				goto fail;
156			}
157			n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_RET_OFFSET,
158				   os_getpid());
159			if (n < 0)
160				fatal_perror("check_sysemu : failed to modify "
161					     "system call return");
162			break;
163		}
164		else if (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP))
165			count++;
166		else {
167			non_fatal("check_sysemu: expected SIGTRAP or "
168				  "(SIGTRAP | 0x80), got status = %d\n",
169				  status);
170			goto fail;
171		}
172	}
173	stop_ptraced_child(pid, 0);
174
175	os_info("OK\n");
176
177	return;
178
179fail:
180	stop_ptraced_child(pid, 1);
181	fatal("missing\n");
182}
183
184static void __init check_ptrace(void)
185{
186	int pid, syscall, n, status;
187
188	os_info("Checking that ptrace can change system call numbers...");
189	pid = start_ptraced_child();
190
191	if ((ptrace(PTRACE_SETOPTIONS, pid, 0,
192		   (void *) PTRACE_O_TRACESYSGOOD) < 0))
193		fatal_perror("check_ptrace: PTRACE_SETOPTIONS failed");
194
195	while (1) {
196		if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
197			fatal_perror("check_ptrace : ptrace failed");
198
199		CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
200		if (n < 0)
201			fatal_perror("check_ptrace : wait failed");
202
203		if (!WIFSTOPPED(status) ||
204		   (WSTOPSIG(status) != (SIGTRAP | 0x80)))
205			fatal("check_ptrace : expected (SIGTRAP|0x80), "
206			       "got status = %d", status);
207
208		syscall = ptrace(PTRACE_PEEKUSER, pid, PT_SYSCALL_NR_OFFSET,
209				 0);
210		if (syscall == __NR_getpid) {
211			n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET,
212				   __NR_getppid);
213			if (n < 0)
214				fatal_perror("check_ptrace : failed to modify "
215					     "system call");
216			break;
217		}
218	}
219	stop_ptraced_child(pid, 0);
220	os_info("OK\n");
221	check_sysemu();
222}
223
224extern void check_tmpexec(void);
225
226static void __init check_coredump_limit(void)
227{
228	struct rlimit lim;
229	int err = getrlimit(RLIMIT_CORE, &lim);
230
231	if (err) {
232		perror("Getting core dump limit");
233		return;
234	}
235
236	os_info("Core dump limits :\n\tsoft - ");
237	if (lim.rlim_cur == RLIM_INFINITY)
238		os_info("NONE\n");
239	else
240		os_info("%llu\n", (unsigned long long)lim.rlim_cur);
241
242	os_info("\thard - ");
243	if (lim.rlim_max == RLIM_INFINITY)
244		os_info("NONE\n");
245	else
246		os_info("%llu\n", (unsigned long long)lim.rlim_max);
247}
248
249void  __init get_host_cpu_features(
250		void (*flags_helper_func)(char *line),
251		void (*cache_helper_func)(char *line))
252{
253	FILE *cpuinfo;
254	char *line = NULL;
255	size_t len = 0;
256	int done_parsing = 0;
257
258	cpuinfo = fopen("/proc/cpuinfo", "r");
259	if (cpuinfo == NULL) {
260		os_info("Failed to get host CPU features\n");
261	} else {
262		while ((getline(&line, &len, cpuinfo)) != -1) {
263			if (strstr(line, "flags")) {
264				flags_helper_func(line);
265				done_parsing++;
266			}
267			if (strstr(line, "cache_alignment")) {
268				cache_helper_func(line);
269				done_parsing++;
270			}
271			free(line);
272			line = NULL;
273			if (done_parsing > 1)
274				break;
275		}
276		fclose(cpuinfo);
277	}
278}
279
280
281void __init os_early_checks(void)
282{
283	int pid;
284
285	/* Print out the core dump limits early */
286	check_coredump_limit();
287
288	check_ptrace();
289
290	/* Need to check this early because mmapping happens before the
291	 * kernel is running.
292	 */
293	check_tmpexec();
294
295	pid = start_ptraced_child();
296	if (init_pid_registers(pid))
297		fatal("Failed to initialize default registers");
298	stop_ptraced_child(pid, 1);
299}
300
301int __init parse_iomem(char *str, int *add)
302{
303	struct iomem_region *new;
304	struct stat64 buf;
305	char *file, *driver;
306	int fd, size;
307
308	driver = str;
309	file = strchr(str,',');
310	if (file == NULL) {
311		os_warn("parse_iomem : failed to parse iomem\n");
312		goto out;
313	}
314	*file = '\0';
315	file++;
316	fd = open(file, O_RDWR, 0);
317	if (fd < 0) {
318		perror("parse_iomem - Couldn't open io file");
319		goto out;
320	}
321
322	if (fstat64(fd, &buf) < 0) {
323		perror("parse_iomem - cannot stat_fd file");
324		goto out_close;
325	}
326
327	new = malloc(sizeof(*new));
328	if (new == NULL) {
329		perror("Couldn't allocate iomem_region struct");
330		goto out_close;
331	}
332
333	size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1);
334
335	*new = ((struct iomem_region) { .next		= iomem_regions,
336					.driver		= driver,
337					.fd		= fd,
338					.size		= size,
339					.phys		= 0,
340					.virt		= 0 });
341	iomem_regions = new;
342	iomem_size += new->size + UM_KERN_PAGE_SIZE;
343
344	return 0;
345 out_close:
346	close(fd);
347 out:
348	return 1;
349}
350