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1da177e4 LT |
1 | /* |
2 | * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com) | |
3 | * Licensed under the GPL | |
4 | */ | |
5 | ||
6 | #include <stdio.h> | |
7 | #include <unistd.h> | |
8 | #include <signal.h> | |
9 | #include <sched.h> | |
10 | #include <errno.h> | |
11 | #include <stdarg.h> | |
12 | #include <stdlib.h> | |
13 | #include <setjmp.h> | |
14 | #include <sys/time.h> | |
15 | #include <sys/wait.h> | |
16 | #include <sys/mman.h> | |
17 | #include <asm/unistd.h> | |
18 | #include <asm/page.h> | |
19 | #include "user_util.h" | |
20 | #include "kern_util.h" | |
21 | #include "user.h" | |
22 | #include "process.h" | |
23 | #include "signal_kern.h" | |
24 | #include "signal_user.h" | |
25 | #include "sysdep/ptrace.h" | |
26 | #include "sysdep/sigcontext.h" | |
27 | #include "irq_user.h" | |
28 | #include "ptrace_user.h" | |
29 | #include "time_user.h" | |
30 | #include "init.h" | |
31 | #include "os.h" | |
32 | #include "uml-config.h" | |
33 | #include "ptrace_user.h" | |
34 | #include "choose-mode.h" | |
35 | #include "mode.h" | |
36 | #ifdef UML_CONFIG_MODE_SKAS | |
37 | #include "skas.h" | |
38 | #include "skas_ptrace.h" | |
39 | #include "registers.h" | |
40 | #endif | |
41 | ||
42 | void init_new_thread_stack(void *sig_stack, void (*usr1_handler)(int)) | |
43 | { | |
44 | int flags = 0, pages; | |
45 | ||
46 | if(sig_stack != NULL){ | |
47 | pages = (1 << UML_CONFIG_KERNEL_STACK_ORDER); | |
48 | set_sigstack(sig_stack, pages * page_size()); | |
49 | flags = SA_ONSTACK; | |
50 | } | |
51 | if(usr1_handler) set_handler(SIGUSR1, usr1_handler, flags, -1); | |
52 | } | |
53 | ||
54 | void init_new_thread_signals(int altstack) | |
55 | { | |
56 | int flags = altstack ? SA_ONSTACK : 0; | |
57 | ||
58 | set_handler(SIGSEGV, (__sighandler_t) sig_handler, flags, | |
59 | SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1); | |
60 | set_handler(SIGTRAP, (__sighandler_t) sig_handler, flags, | |
61 | SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1); | |
62 | set_handler(SIGFPE, (__sighandler_t) sig_handler, flags, | |
63 | SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1); | |
64 | set_handler(SIGILL, (__sighandler_t) sig_handler, flags, | |
65 | SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1); | |
66 | set_handler(SIGBUS, (__sighandler_t) sig_handler, flags, | |
67 | SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1); | |
68 | set_handler(SIGWINCH, (__sighandler_t) sig_handler, flags, | |
69 | SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1); | |
70 | set_handler(SIGUSR2, (__sighandler_t) sig_handler, | |
71 | flags, SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1); | |
72 | signal(SIGHUP, SIG_IGN); | |
73 | ||
74 | init_irq_signals(altstack); | |
75 | } | |
76 | ||
77 | struct tramp { | |
78 | int (*tramp)(void *); | |
79 | void *tramp_data; | |
80 | unsigned long temp_stack; | |
81 | int flags; | |
82 | int pid; | |
83 | }; | |
84 | ||
85 | /* See above for why sigkill is here */ | |
86 | ||
87 | int sigkill = SIGKILL; | |
88 | ||
89 | int outer_tramp(void *arg) | |
90 | { | |
91 | struct tramp *t; | |
92 | int sig = sigkill; | |
93 | ||
94 | t = arg; | |
95 | t->pid = clone(t->tramp, (void *) t->temp_stack + page_size()/2, | |
96 | t->flags, t->tramp_data); | |
97 | if(t->pid > 0) wait_for_stop(t->pid, SIGSTOP, PTRACE_CONT, NULL); | |
98 | kill(os_getpid(), sig); | |
99 | _exit(0); | |
100 | } | |
101 | ||
102 | int start_fork_tramp(void *thread_arg, unsigned long temp_stack, | |
103 | int clone_flags, int (*tramp)(void *)) | |
104 | { | |
105 | struct tramp arg; | |
106 | unsigned long sp; | |
107 | int new_pid, status, err; | |
108 | ||
109 | /* The trampoline will run on the temporary stack */ | |
110 | sp = stack_sp(temp_stack); | |
111 | ||
112 | clone_flags |= CLONE_FILES | SIGCHLD; | |
113 | ||
114 | arg.tramp = tramp; | |
115 | arg.tramp_data = thread_arg; | |
116 | arg.temp_stack = temp_stack; | |
117 | arg.flags = clone_flags; | |
118 | ||
119 | /* Start the process and wait for it to kill itself */ | |
120 | new_pid = clone(outer_tramp, (void *) sp, clone_flags, &arg); | |
121 | if(new_pid < 0) | |
122 | return(new_pid); | |
123 | ||
124 | CATCH_EINTR(err = waitpid(new_pid, &status, 0)); | |
125 | if(err < 0) | |
126 | panic("Waiting for outer trampoline failed - errno = %d", | |
127 | errno); | |
128 | ||
129 | if(!WIFSIGNALED(status) || (WTERMSIG(status) != SIGKILL)) | |
130 | panic("outer trampoline didn't exit with SIGKILL, " | |
131 | "status = %d", status); | |
132 | ||
133 | return(arg.pid); | |
134 | } | |
135 | ||
136 | static int ptrace_child(void *arg) | |
137 | { | |
138 | int ret; | |
139 | int pid = os_getpid(), ppid = getppid(); | |
140 | int sc_result; | |
141 | ||
142 | if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0){ | |
143 | perror("ptrace"); | |
144 | os_kill_process(pid, 0); | |
145 | } | |
146 | os_stop_process(pid); | |
147 | ||
148 | /*This syscall will be intercepted by the parent. Don't call more than | |
149 | * once, please.*/ | |
150 | sc_result = os_getpid(); | |
151 | ||
152 | if (sc_result == pid) | |
153 | ret = 1; /*Nothing modified by the parent, we are running | |
154 | normally.*/ | |
155 | else if (sc_result == ppid) | |
156 | ret = 0; /*Expected in check_ptrace and check_sysemu when they | |
157 | succeed in modifying the stack frame*/ | |
158 | else | |
159 | ret = 2; /*Serious trouble! This could be caused by a bug in | |
160 | host 2.6 SKAS3/2.6 patch before release -V6, together | |
161 | with a bug in the UML code itself.*/ | |
162 | _exit(ret); | |
163 | } | |
164 | ||
165 | static int start_ptraced_child(void **stack_out) | |
166 | { | |
167 | void *stack; | |
168 | unsigned long sp; | |
169 | int pid, n, status; | |
170 | ||
171 | stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC, | |
172 | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); | |
173 | if(stack == MAP_FAILED) | |
174 | panic("check_ptrace : mmap failed, errno = %d", errno); | |
175 | sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *); | |
176 | pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL); | |
177 | if(pid < 0) | |
178 | panic("check_ptrace : clone failed, errno = %d", errno); | |
179 | CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); | |
180 | if(n < 0) | |
181 | panic("check_ptrace : wait failed, errno = %d", errno); | |
182 | if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) | |
183 | panic("check_ptrace : expected SIGSTOP, got status = %d", | |
184 | status); | |
185 | ||
186 | *stack_out = stack; | |
187 | return(pid); | |
188 | } | |
189 | ||
190 | /* When testing for SYSEMU support, if it is one of the broken versions, we must | |
191 | * just avoid using sysemu, not panic, but only if SYSEMU features are broken. | |
192 | * So only for SYSEMU features we test mustpanic, while normal host features | |
193 | * must work anyway!*/ | |
194 | static int stop_ptraced_child(int pid, void *stack, int exitcode, int mustpanic) | |
195 | { | |
196 | int status, n, ret = 0; | |
197 | ||
198 | if(ptrace(PTRACE_CONT, pid, 0, 0) < 0) | |
199 | panic("check_ptrace : ptrace failed, errno = %d", errno); | |
200 | CATCH_EINTR(n = waitpid(pid, &status, 0)); | |
201 | if(!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) { | |
202 | int exit_with = WEXITSTATUS(status); | |
203 | if (exit_with == 2) | |
204 | printk("check_ptrace : child exited with status 2. " | |
205 | "Serious trouble happening! Try updating your " | |
206 | "host skas patch!\nDisabling SYSEMU support."); | |
207 | printk("check_ptrace : child exited with exitcode %d, while " | |
208 | "expecting %d; status 0x%x", exit_with, | |
209 | exitcode, status); | |
210 | if (mustpanic) | |
211 | panic("\n"); | |
212 | else | |
213 | printk("\n"); | |
214 | ret = -1; | |
215 | } | |
216 | ||
217 | if(munmap(stack, PAGE_SIZE) < 0) | |
218 | panic("check_ptrace : munmap failed, errno = %d", errno); | |
219 | return ret; | |
220 | } | |
221 | ||
222 | static int force_sysemu_disabled = 0; | |
223 | ||
224 | static int __init nosysemu_cmd_param(char *str, int* add) | |
225 | { | |
226 | force_sysemu_disabled = 1; | |
227 | return 0; | |
228 | } | |
229 | ||
230 | __uml_setup("nosysemu", nosysemu_cmd_param, | |
231 | "nosysemu\n" | |
232 | " Turns off syscall emulation patch for ptrace (SYSEMU) on.\n" | |
233 | " SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n" | |
234 | " behaviour of ptrace() and helps reducing host context switch rate.\n" | |
235 | " To make it working, you need a kernel patch for your host, too.\n" | |
236 | " See http://perso.wanadoo.fr/laurent.vivier/UML/ for further information.\n\n"); | |
237 | ||
238 | static void __init check_sysemu(void) | |
239 | { | |
240 | void *stack; | |
241 | int pid, syscall, n, status, count=0; | |
242 | ||
243 | printk("Checking syscall emulation patch for ptrace..."); | |
244 | sysemu_supported = 0; | |
245 | pid = start_ptraced_child(&stack); | |
246 | ||
247 | if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0) | |
248 | goto fail; | |
249 | ||
250 | CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); | |
251 | if (n < 0) | |
252 | panic("check_sysemu : wait failed, errno = %d", errno); | |
253 | if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP)) | |
254 | panic("check_sysemu : expected SIGTRAP, " | |
255 | "got status = %d", status); | |
256 | ||
257 | n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, | |
258 | os_getpid()); | |
259 | if(n < 0) | |
260 | panic("check_sysemu : failed to modify system " | |
261 | "call return, errno = %d", errno); | |
262 | ||
263 | if (stop_ptraced_child(pid, stack, 0, 0) < 0) | |
264 | goto fail_stopped; | |
265 | ||
266 | sysemu_supported = 1; | |
267 | printk("OK\n"); | |
268 | set_using_sysemu(!force_sysemu_disabled); | |
269 | ||
270 | printk("Checking advanced syscall emulation patch for ptrace..."); | |
271 | pid = start_ptraced_child(&stack); | |
272 | while(1){ | |
273 | count++; | |
274 | if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0) | |
275 | goto fail; | |
276 | CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); | |
277 | if(n < 0) | |
278 | panic("check_ptrace : wait failed, errno = %d", errno); | |
279 | if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP)) | |
280 | panic("check_ptrace : expected (SIGTRAP|SYSCALL_TRAP), " | |
281 | "got status = %d", status); | |
282 | ||
283 | syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET, | |
284 | 0); | |
285 | if(syscall == __NR_getpid){ | |
286 | if (!count) | |
287 | panic("check_ptrace : SYSEMU_SINGLESTEP doesn't singlestep"); | |
288 | n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, | |
289 | os_getpid()); | |
290 | if(n < 0) | |
291 | panic("check_sysemu : failed to modify system " | |
292 | "call return, errno = %d", errno); | |
293 | break; | |
294 | } | |
295 | } | |
296 | if (stop_ptraced_child(pid, stack, 0, 0) < 0) | |
297 | goto fail_stopped; | |
298 | ||
299 | sysemu_supported = 2; | |
300 | printk("OK\n"); | |
301 | ||
302 | if ( !force_sysemu_disabled ) | |
303 | set_using_sysemu(sysemu_supported); | |
304 | return; | |
305 | ||
306 | fail: | |
307 | stop_ptraced_child(pid, stack, 1, 0); | |
308 | fail_stopped: | |
309 | printk("missing\n"); | |
310 | } | |
311 | ||
312 | void __init check_ptrace(void) | |
313 | { | |
314 | void *stack; | |
315 | int pid, syscall, n, status; | |
316 | ||
317 | printk("Checking that ptrace can change system call numbers..."); | |
318 | pid = start_ptraced_child(&stack); | |
319 | ||
320 | if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0) | |
321 | panic("check_ptrace: PTRACE_SETOPTIONS failed, errno = %d", errno); | |
322 | ||
323 | while(1){ | |
324 | if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0) | |
325 | panic("check_ptrace : ptrace failed, errno = %d", | |
326 | errno); | |
327 | CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); | |
328 | if(n < 0) | |
329 | panic("check_ptrace : wait failed, errno = %d", errno); | |
330 | if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP + 0x80)) | |
331 | panic("check_ptrace : expected SIGTRAP + 0x80, " | |
332 | "got status = %d", status); | |
333 | ||
334 | syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET, | |
335 | 0); | |
336 | if(syscall == __NR_getpid){ | |
337 | n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET, | |
338 | __NR_getppid); | |
339 | if(n < 0) | |
340 | panic("check_ptrace : failed to modify system " | |
341 | "call, errno = %d", errno); | |
342 | break; | |
343 | } | |
344 | } | |
345 | stop_ptraced_child(pid, stack, 0, 1); | |
346 | printk("OK\n"); | |
347 | check_sysemu(); | |
348 | } | |
349 | ||
350 | int run_kernel_thread(int (*fn)(void *), void *arg, void **jmp_ptr) | |
351 | { | |
352 | sigjmp_buf buf; | |
353 | int n; | |
354 | ||
355 | *jmp_ptr = &buf; | |
356 | n = sigsetjmp(buf, 1); | |
357 | if(n != 0) | |
358 | return(n); | |
359 | (*fn)(arg); | |
360 | return(0); | |
361 | } | |
362 | ||
363 | void forward_pending_sigio(int target) | |
364 | { | |
365 | sigset_t sigs; | |
366 | ||
367 | if(sigpending(&sigs)) | |
368 | panic("forward_pending_sigio : sigpending failed"); | |
369 | if(sigismember(&sigs, SIGIO)) | |
370 | kill(target, SIGIO); | |
371 | } | |
372 | ||
373 | #ifdef UML_CONFIG_MODE_SKAS | |
374 | static inline int check_skas3_ptrace_support(void) | |
375 | { | |
376 | struct ptrace_faultinfo fi; | |
377 | void *stack; | |
378 | int pid, n, ret = 1; | |
379 | ||
380 | printf("Checking for the skas3 patch in the host..."); | |
381 | pid = start_ptraced_child(&stack); | |
382 | ||
383 | n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi); | |
384 | if (n < 0) { | |
385 | if(errno == EIO) | |
386 | printf("not found\n"); | |
387 | else { | |
388 | perror("not found"); | |
389 | } | |
390 | ret = 0; | |
391 | } else { | |
392 | printf("found\n"); | |
393 | } | |
394 | ||
395 | init_registers(pid); | |
396 | stop_ptraced_child(pid, stack, 1, 1); | |
397 | ||
398 | return(ret); | |
399 | } | |
400 | ||
401 | int can_do_skas(void) | |
402 | { | |
403 | int ret = 1; | |
404 | ||
405 | printf("Checking for /proc/mm..."); | |
406 | if (os_access("/proc/mm", OS_ACC_W_OK) < 0) { | |
407 | printf("not found\n"); | |
408 | ret = 0; | |
409 | goto out; | |
410 | } else { | |
411 | printf("found\n"); | |
412 | } | |
413 | ||
414 | ret = check_skas3_ptrace_support(); | |
415 | out: | |
416 | return ret; | |
417 | } | |
418 | #else | |
419 | int can_do_skas(void) | |
420 | { | |
421 | return(0); | |
422 | } | |
423 | #endif |