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/ldt.h>
21 #include <asm/unistd.h>
22 #include <init.h>
23 #include <os.h>
24 #include <kern_util.h>
25 #include <mem_user.h>
26 #include <ptrace_user.h>
27 #include <registers.h>
28 #include <skas.h>
29 #include "internal.h"
30
ptrace_child(void)31 static void ptrace_child(void)
32 {
33 int ret;
34 /* Calling os_getpid because some libcs cached getpid incorrectly */
35 int pid = os_getpid(), ppid = getppid();
36 int sc_result;
37
38 if (change_sig(SIGWINCH, 0) < 0 ||
39 ptrace(PTRACE_TRACEME, 0, 0, 0) < 0) {
40 perror("ptrace");
41 kill(pid, SIGKILL);
42 }
43 kill(pid, SIGSTOP);
44
45 /*
46 * This syscall will be intercepted by the parent. Don't call more than
47 * once, please.
48 */
49 sc_result = os_getpid();
50
51 if (sc_result == pid)
52 /* Nothing modified by the parent, we are running normally. */
53 ret = 1;
54 else if (sc_result == ppid)
55 /*
56 * Expected in check_ptrace and check_sysemu when they succeed
57 * in modifying the stack frame
58 */
59 ret = 0;
60 else
61 /* Serious trouble! This could be caused by a bug in host 2.6
62 * SKAS3/2.6 patch before release -V6, together with a bug in
63 * the UML code itself.
64 */
65 ret = 2;
66
67 exit(ret);
68 }
69
fatal_perror(const char * str)70 static void fatal_perror(const char *str)
71 {
72 perror(str);
73 exit(1);
74 }
75
fatal(char * fmt,...)76 static void fatal(char *fmt, ...)
77 {
78 va_list list;
79
80 va_start(list, fmt);
81 vfprintf(stderr, fmt, list);
82 va_end(list);
83
84 exit(1);
85 }
86
non_fatal(char * fmt,...)87 static void non_fatal(char *fmt, ...)
88 {
89 va_list list;
90
91 va_start(list, fmt);
92 vfprintf(stderr, fmt, list);
93 va_end(list);
94 }
95
start_ptraced_child(void)96 static int start_ptraced_child(void)
97 {
98 int pid, n, status;
99
100 fflush(stdout);
101
102 pid = fork();
103 if (pid == 0)
104 ptrace_child();
105 else if (pid < 0)
106 fatal_perror("start_ptraced_child : fork failed");
107
108 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
109 if (n < 0)
110 fatal_perror("check_ptrace : waitpid failed");
111 if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
112 fatal("check_ptrace : expected SIGSTOP, got status = %d",
113 status);
114
115 return pid;
116 }
117
stop_ptraced_child(int pid,int exitcode)118 static void stop_ptraced_child(int pid, int exitcode)
119 {
120 int status, n;
121
122 if (ptrace(PTRACE_CONT, pid, 0, 0) < 0)
123 fatal_perror("stop_ptraced_child : ptrace failed");
124
125 CATCH_EINTR(n = waitpid(pid, &status, 0));
126 if (!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {
127 int exit_with = WEXITSTATUS(status);
128 fatal("stop_ptraced_child : child exited with exitcode %d, "
129 "while expecting %d; status 0x%x\n", exit_with,
130 exitcode, status);
131 }
132 }
133
check_sysemu(void)134 static void __init check_sysemu(void)
135 {
136 int pid, n, status, count=0;
137
138 os_info("Checking syscall emulation for ptrace...");
139 pid = start_ptraced_child();
140
141 if ((ptrace(PTRACE_SETOPTIONS, pid, 0,
142 (void *) PTRACE_O_TRACESYSGOOD) < 0))
143 fatal_perror("check_sysemu: PTRACE_SETOPTIONS failed");
144
145 while (1) {
146 count++;
147 if (ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
148 goto fail;
149 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
150 if (n < 0)
151 fatal_perror("check_sysemu: wait failed");
152
153 if (WIFSTOPPED(status) &&
154 (WSTOPSIG(status) == (SIGTRAP|0x80))) {
155 if (!count) {
156 non_fatal("check_sysemu: SYSEMU_SINGLESTEP "
157 "doesn't singlestep");
158 goto fail;
159 }
160 n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_RET_OFFSET,
161 os_getpid());
162 if (n < 0)
163 fatal_perror("check_sysemu : failed to modify "
164 "system call return");
165 break;
166 }
167 else if (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP))
168 count++;
169 else {
170 non_fatal("check_sysemu: expected SIGTRAP or "
171 "(SIGTRAP | 0x80), got status = %d\n",
172 status);
173 goto fail;
174 }
175 }
176 stop_ptraced_child(pid, 0);
177
178 os_info("OK\n");
179
180 return;
181
182 fail:
183 stop_ptraced_child(pid, 1);
184 fatal("missing\n");
185 }
186
check_ptrace(void)187 static void __init check_ptrace(void)
188 {
189 int pid, syscall, n, status;
190
191 os_info("Checking that ptrace can change system call numbers...");
192 pid = start_ptraced_child();
193
194 if ((ptrace(PTRACE_SETOPTIONS, pid, 0,
195 (void *) PTRACE_O_TRACESYSGOOD) < 0))
196 fatal_perror("check_ptrace: PTRACE_SETOPTIONS failed");
197
198 while (1) {
199 if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
200 fatal_perror("check_ptrace : ptrace failed");
201
202 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
203 if (n < 0)
204 fatal_perror("check_ptrace : wait failed");
205
206 if (!WIFSTOPPED(status) ||
207 (WSTOPSIG(status) != (SIGTRAP | 0x80)))
208 fatal("check_ptrace : expected (SIGTRAP|0x80), "
209 "got status = %d", status);
210
211 syscall = ptrace(PTRACE_PEEKUSER, pid, PT_SYSCALL_NR_OFFSET,
212 0);
213 if (syscall == __NR_getpid) {
214 n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET,
215 __NR_getppid);
216 if (n < 0)
217 fatal_perror("check_ptrace : failed to modify "
218 "system call");
219 break;
220 }
221 }
222 stop_ptraced_child(pid, 0);
223 os_info("OK\n");
224 check_sysemu();
225 }
226
check_coredump_limit(void)227 static void __init check_coredump_limit(void)
228 {
229 struct rlimit lim;
230 int err = getrlimit(RLIMIT_CORE, &lim);
231
232 if (err) {
233 perror("Getting core dump limit");
234 return;
235 }
236
237 os_info("Core dump limits :\n\tsoft - ");
238 if (lim.rlim_cur == RLIM_INFINITY)
239 os_info("NONE\n");
240 else
241 os_info("%llu\n", (unsigned long long)lim.rlim_cur);
242
243 os_info("\thard - ");
244 if (lim.rlim_max == RLIM_INFINITY)
245 os_info("NONE\n");
246 else
247 os_info("%llu\n", (unsigned long long)lim.rlim_max);
248 }
249
get_host_cpu_features(void (* flags_helper_func)(char * line),void (* cache_helper_func)(char * line))250 void __init get_host_cpu_features(
251 void (*flags_helper_func)(char *line),
252 void (*cache_helper_func)(char *line))
253 {
254 FILE *cpuinfo;
255 char *line = NULL;
256 size_t len = 0;
257 int done_parsing = 0;
258
259 cpuinfo = fopen("/proc/cpuinfo", "r");
260 if (cpuinfo == NULL) {
261 os_info("Failed to get host CPU features\n");
262 } else {
263 while ((getline(&line, &len, cpuinfo)) != -1) {
264 if (strstr(line, "flags")) {
265 flags_helper_func(line);
266 done_parsing++;
267 }
268 if (strstr(line, "cache_alignment")) {
269 cache_helper_func(line);
270 done_parsing++;
271 }
272 free(line);
273 line = NULL;
274 if (done_parsing > 1)
275 break;
276 }
277 fclose(cpuinfo);
278 }
279 }
280
281
os_early_checks(void)282 void __init os_early_checks(void)
283 {
284 int pid;
285
286 /* Print out the core dump limits early */
287 check_coredump_limit();
288
289 check_ptrace();
290
291 /* Need to check this early because mmapping happens before the
292 * kernel is running.
293 */
294 check_tmpexec();
295
296 pid = start_ptraced_child();
297 if (init_pid_registers(pid))
298 fatal("Failed to initialize default registers");
299 stop_ptraced_child(pid, 1);
300 }
301
parse_iomem(char * str,int * add)302 int __init parse_iomem(char *str, int *add)
303 {
304 struct iomem_region *new;
305 struct stat64 buf;
306 char *file, *driver;
307 int fd, size;
308
309 driver = str;
310 file = strchr(str,',');
311 if (file == NULL) {
312 os_warn("parse_iomem : failed to parse iomem\n");
313 goto out;
314 }
315 *file = '\0';
316 file++;
317 fd = open(file, O_RDWR, 0);
318 if (fd < 0) {
319 perror("parse_iomem - Couldn't open io file");
320 goto out;
321 }
322
323 if (fstat64(fd, &buf) < 0) {
324 perror("parse_iomem - cannot stat_fd file");
325 goto out_close;
326 }
327
328 new = malloc(sizeof(*new));
329 if (new == NULL) {
330 perror("Couldn't allocate iomem_region struct");
331 goto out_close;
332 }
333
334 size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1);
335
336 *new = ((struct iomem_region) { .next = iomem_regions,
337 .driver = driver,
338 .fd = fd,
339 .size = size,
340 .phys = 0,
341 .virt = 0 });
342 iomem_regions = new;
343 iomem_size += new->size + UM_KERN_PAGE_SIZE;
344
345 return 0;
346 out_close:
347 close(fd);
348 out:
349 return 1;
350 }
351