Line data Source code
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 :
28 4 : static void ptrace_child(void)
29 : {
30 : int ret;
31 : /* Calling os_getpid because some libcs cached getpid incorrectly */
32 4 : int pid = os_getpid(), ppid = getppid();
33 : int sc_result;
34 :
35 8 : if (change_sig(SIGWINCH, 0) < 0 ||
36 4 : ptrace(PTRACE_TRACEME, 0, 0, 0) < 0) {
37 0 : perror("ptrace");
38 0 : kill(pid, SIGKILL);
39 : }
40 4 : kill(pid, SIGSTOP);
41 :
42 : /*
43 : * This syscall will be intercepted by the parent. Don't call more than
44 : * once, please.
45 : */
46 4 : sc_result = os_getpid();
47 :
48 4 : if (sc_result == pid)
49 : /* Nothing modified by the parent, we are running normally. */
50 : ret = 1;
51 3 : 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 0 : ret = 2;
63 :
64 4 : exit(ret);
65 : }
66 :
67 0 : static void fatal_perror(const char *str)
68 : {
69 0 : perror(str);
70 0 : exit(1);
71 : }
72 :
73 0 : static void fatal(char *fmt, ...)
74 : {
75 : va_list list;
76 :
77 0 : va_start(list, fmt);
78 0 : vfprintf(stderr, fmt, list);
79 0 : va_end(list);
80 :
81 0 : exit(1);
82 : }
83 :
84 0 : static void non_fatal(char *fmt, ...)
85 : {
86 : va_list list;
87 :
88 0 : va_start(list, fmt);
89 0 : vfprintf(stderr, fmt, list);
90 0 : va_end(list);
91 0 : }
92 :
93 14 : static int start_ptraced_child(void)
94 : {
95 : int pid, n, status;
96 :
97 14 : fflush(stdout);
98 :
99 14 : pid = fork();
100 14 : if (pid == 0)
101 4 : ptrace_child();
102 10 : else if (pid < 0)
103 0 : fatal_perror("start_ptraced_child : fork failed");
104 :
105 10 : CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
106 10 : if (n < 0)
107 0 : fatal_perror("check_ptrace : waitpid failed");
108 10 : if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
109 0 : fatal("check_ptrace : expected SIGSTOP, got status = %d",
110 : status);
111 :
112 10 : return pid;
113 : }
114 :
115 : /* When testing for SYSEMU support, if it is one of the broken versions, we
116 : * must just avoid using sysemu, not panic, but only if SYSEMU features are
117 : * broken.
118 : * So only for SYSEMU features we test mustpanic, while normal host features
119 : * must work anyway!
120 : */
121 10 : static int stop_ptraced_child(int pid, int exitcode, int mustexit)
122 : {
123 10 : int status, n, ret = 0;
124 :
125 10 : if (ptrace(PTRACE_CONT, pid, 0, 0) < 0) {
126 0 : perror("stop_ptraced_child : ptrace failed");
127 0 : return -1;
128 : }
129 10 : CATCH_EINTR(n = waitpid(pid, &status, 0));
130 10 : if (!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {
131 0 : int exit_with = WEXITSTATUS(status);
132 0 : if (exit_with == 2)
133 0 : non_fatal("check_ptrace : child exited with status 2. "
134 : "\nDisabling SYSEMU support.\n");
135 0 : non_fatal("check_ptrace : child exited with exitcode %d, while "
136 : "expecting %d; status 0x%x\n", exit_with,
137 : exitcode, status);
138 0 : if (mustexit)
139 0 : exit(1);
140 : ret = -1;
141 : }
142 :
143 : return ret;
144 : }
145 :
146 : /* Changed only during early boot */
147 : static int force_sysemu_disabled = 0;
148 :
149 0 : static int __init nosysemu_cmd_param(char *str, int* add)
150 : {
151 0 : force_sysemu_disabled = 1;
152 0 : return 0;
153 : }
154 :
155 : __uml_setup("nosysemu", nosysemu_cmd_param,
156 : "nosysemu\n"
157 : " Turns off syscall emulation patch for ptrace (SYSEMU).\n"
158 : " SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n"
159 : " behaviour of ptrace() and helps reduce host context switch rates.\n"
160 : " To make it work, you need a kernel patch for your host, too.\n"
161 : " See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n"
162 : " information.\n\n");
163 :
164 4 : static void __init check_sysemu(void)
165 : {
166 : unsigned long regs[MAX_REG_NR];
167 4 : int pid, n, status, count=0;
168 :
169 4 : os_info("Checking syscall emulation patch for ptrace...");
170 4 : sysemu_supported = 0;
171 4 : pid = start_ptraced_child();
172 :
173 3 : if (ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0)
174 : goto fail;
175 :
176 3 : CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
177 3 : if (n < 0)
178 0 : fatal_perror("check_sysemu : wait failed");
179 3 : if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
180 0 : fatal("check_sysemu : expected SIGTRAP, got status = %d\n",
181 : status);
182 :
183 3 : if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
184 0 : fatal_perror("check_sysemu : PTRACE_GETREGS failed");
185 3 : if (PT_SYSCALL_NR(regs) != __NR_getpid) {
186 0 : non_fatal("check_sysemu got system call number %d, "
187 : "expected %d...", PT_SYSCALL_NR(regs), __NR_getpid);
188 0 : goto fail;
189 : }
190 :
191 3 : n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_RET_OFFSET, os_getpid());
192 3 : if (n < 0) {
193 0 : non_fatal("check_sysemu : failed to modify system call "
194 : "return");
195 0 : goto fail;
196 : }
197 :
198 3 : if (stop_ptraced_child(pid, 0, 0) < 0)
199 : goto fail_stopped;
200 :
201 3 : sysemu_supported = 1;
202 3 : os_info("OK\n");
203 3 : set_using_sysemu(!force_sysemu_disabled);
204 :
205 3 : os_info("Checking advanced syscall emulation patch for ptrace...");
206 3 : pid = start_ptraced_child();
207 :
208 2 : if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
209 : (void *) PTRACE_O_TRACESYSGOOD) < 0))
210 0 : fatal_perror("check_sysemu: PTRACE_OLDSETOPTIONS failed");
211 :
212 : while (1) {
213 54 : count++;
214 54 : if (ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
215 : goto fail;
216 54 : CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
217 54 : if (n < 0)
218 0 : fatal_perror("check_sysemu: wait failed");
219 :
220 108 : if (WIFSTOPPED(status) &&
221 54 : (WSTOPSIG(status) == (SIGTRAP|0x80))) {
222 : if (!count) {
223 : non_fatal("check_sysemu: SYSEMU_SINGLESTEP "
224 : "doesn't singlestep");
225 : goto fail;
226 : }
227 2 : n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_RET_OFFSET,
228 : os_getpid());
229 2 : if (n < 0)
230 0 : fatal_perror("check_sysemu : failed to modify "
231 : "system call return");
232 : break;
233 : }
234 52 : else if (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP))
235 : count++;
236 : else {
237 0 : non_fatal("check_sysemu: expected SIGTRAP or "
238 : "(SIGTRAP | 0x80), got status = %d\n",
239 : status);
240 0 : goto fail;
241 : }
242 : }
243 2 : if (stop_ptraced_child(pid, 0, 0) < 0)
244 : goto fail_stopped;
245 :
246 2 : sysemu_supported = 2;
247 2 : os_info("OK\n");
248 :
249 2 : if (!force_sysemu_disabled)
250 2 : set_using_sysemu(sysemu_supported);
251 2 : return;
252 :
253 : fail:
254 0 : stop_ptraced_child(pid, 1, 0);
255 : fail_stopped:
256 0 : non_fatal("missing\n");
257 : }
258 :
259 5 : static void __init check_ptrace(void)
260 : {
261 : int pid, syscall, n, status;
262 :
263 5 : os_info("Checking that ptrace can change system call numbers...");
264 5 : pid = start_ptraced_child();
265 :
266 4 : if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
267 : (void *) PTRACE_O_TRACESYSGOOD) < 0))
268 0 : fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed");
269 :
270 : while (1) {
271 4 : if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
272 0 : fatal_perror("check_ptrace : ptrace failed");
273 :
274 4 : CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
275 4 : if (n < 0)
276 0 : fatal_perror("check_ptrace : wait failed");
277 :
278 8 : if (!WIFSTOPPED(status) ||
279 4 : (WSTOPSIG(status) != (SIGTRAP | 0x80)))
280 0 : fatal("check_ptrace : expected (SIGTRAP|0x80), "
281 : "got status = %d", status);
282 :
283 4 : syscall = ptrace(PTRACE_PEEKUSER, pid, PT_SYSCALL_NR_OFFSET,
284 : 0);
285 4 : if (syscall == __NR_getpid) {
286 4 : n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET,
287 : __NR_getppid);
288 4 : if (n < 0)
289 0 : fatal_perror("check_ptrace : failed to modify "
290 : "system call");
291 : break;
292 : }
293 : }
294 4 : stop_ptraced_child(pid, 0, 1);
295 4 : os_info("OK\n");
296 4 : check_sysemu();
297 2 : }
298 :
299 : extern void check_tmpexec(void);
300 :
301 5 : static void __init check_coredump_limit(void)
302 : {
303 : struct rlimit lim;
304 5 : int err = getrlimit(RLIMIT_CORE, &lim);
305 :
306 5 : if (err) {
307 0 : perror("Getting core dump limit");
308 0 : return;
309 : }
310 :
311 5 : os_info("Core dump limits :\n\tsoft - ");
312 5 : if (lim.rlim_cur == RLIM_INFINITY)
313 0 : os_info("NONE\n");
314 : else
315 5 : os_info("%llu\n", (unsigned long long)lim.rlim_cur);
316 :
317 5 : os_info("\thard - ");
318 5 : if (lim.rlim_max == RLIM_INFINITY)
319 5 : os_info("NONE\n");
320 : else
321 0 : os_info("%llu\n", (unsigned long long)lim.rlim_max);
322 : }
323 :
324 1 : void __init get_host_cpu_features(
325 : void (*flags_helper_func)(char *line),
326 : void (*cache_helper_func)(char *line))
327 : {
328 : FILE *cpuinfo;
329 1 : char *line = NULL;
330 1 : size_t len = 0;
331 1 : int done_parsing = 0;
332 :
333 1 : cpuinfo = fopen("/proc/cpuinfo", "r");
334 1 : if (cpuinfo == NULL) {
335 0 : os_info("Failed to get host CPU features\n");
336 : } else {
337 21 : while ((getline(&line, &len, cpuinfo)) != -1) {
338 21 : if (strstr(line, "flags")) {
339 2 : flags_helper_func(line);
340 2 : done_parsing++;
341 : }
342 21 : if (strstr(line, "cache_alignment")) {
343 0 : cache_helper_func(line);
344 0 : done_parsing++;
345 : }
346 21 : free(line);
347 21 : line = NULL;
348 21 : if (done_parsing > 1)
349 : break;
350 : }
351 1 : fclose(cpuinfo);
352 : }
353 1 : }
354 :
355 :
356 5 : void __init os_early_checks(void)
357 : {
358 : int pid;
359 :
360 : /* Print out the core dump limits early */
361 5 : check_coredump_limit();
362 :
363 5 : check_ptrace();
364 :
365 : /* Need to check this early because mmapping happens before the
366 : * kernel is running.
367 : */
368 2 : check_tmpexec();
369 :
370 2 : pid = start_ptraced_child();
371 1 : if (init_pid_registers(pid))
372 0 : fatal("Failed to initialize default registers");
373 1 : stop_ptraced_child(pid, 1, 1);
374 1 : }
375 :
376 0 : int __init parse_iomem(char *str, int *add)
377 : {
378 : struct iomem_region *new;
379 : struct stat64 buf;
380 : char *file, *driver;
381 : int fd, size;
382 :
383 0 : driver = str;
384 0 : file = strchr(str,',');
385 0 : if (file == NULL) {
386 0 : os_warn("parse_iomem : failed to parse iomem\n");
387 0 : goto out;
388 : }
389 0 : *file = '\0';
390 0 : file++;
391 0 : fd = open(file, O_RDWR, 0);
392 0 : if (fd < 0) {
393 0 : perror("parse_iomem - Couldn't open io file");
394 0 : goto out;
395 : }
396 :
397 0 : if (fstat64(fd, &buf) < 0) {
398 0 : perror("parse_iomem - cannot stat_fd file");
399 0 : goto out_close;
400 : }
401 :
402 0 : new = malloc(sizeof(*new));
403 0 : if (new == NULL) {
404 0 : perror("Couldn't allocate iomem_region struct");
405 0 : goto out_close;
406 : }
407 :
408 0 : size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1);
409 :
410 0 : *new = ((struct iomem_region) { .next = iomem_regions,
411 : .driver = driver,
412 : .fd = fd,
413 : .size = size,
414 : .phys = 0,
415 : .virt = 0 });
416 0 : iomem_regions = new;
417 0 : iomem_size += new->size + UM_KERN_PAGE_SIZE;
418 :
419 0 : return 0;
420 : out_close:
421 0 : close(fd);
422 : out:
423 : return 1;
424 : }
|
