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 "choose-mode.h" 34 #include "mode.h" 35 #include "tempfile.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(SIGUSR2, (__sighandler_t) sig_handler, 69 flags, SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1); 70 signal(SIGHUP, SIG_IGN); 71 72 init_irq_signals(altstack); 73 } 74 75 struct tramp { 76 int (*tramp)(void *); 77 void *tramp_data; 78 unsigned long temp_stack; 79 int flags; 80 int pid; 81 }; 82 83 /* See above for why sigkill is here */ 84 85 int sigkill = SIGKILL; 86 87 int outer_tramp(void *arg) 88 { 89 struct tramp *t; 90 int sig = sigkill; 91 92 t = arg; 93 t->pid = clone(t->tramp, (void *) t->temp_stack + page_size()/2, 94 t->flags, t->tramp_data); 95 if(t->pid > 0) wait_for_stop(t->pid, SIGSTOP, PTRACE_CONT, NULL); 96 kill(os_getpid(), sig); 97 _exit(0); 98 } 99 100 int start_fork_tramp(void *thread_arg, unsigned long temp_stack, 101 int clone_flags, int (*tramp)(void *)) 102 { 103 struct tramp arg; 104 unsigned long sp; 105 int new_pid, status, err; 106 107 /* The trampoline will run on the temporary stack */ 108 sp = stack_sp(temp_stack); 109 110 clone_flags |= CLONE_FILES | SIGCHLD; 111 112 arg.tramp = tramp; 113 arg.tramp_data = thread_arg; 114 arg.temp_stack = temp_stack; 115 arg.flags = clone_flags; 116 117 /* Start the process and wait for it to kill itself */ 118 new_pid = clone(outer_tramp, (void *) sp, clone_flags, &arg); 119 if(new_pid < 0) 120 return(new_pid); 121 122 CATCH_EINTR(err = waitpid(new_pid, &status, 0)); 123 if(err < 0) 124 panic("Waiting for outer trampoline failed - errno = %d", 125 errno); 126 127 if(!WIFSIGNALED(status) || (WTERMSIG(status) != SIGKILL)) 128 panic("outer trampoline didn't exit with SIGKILL, " 129 "status = %d", status); 130 131 return(arg.pid); 132 } 133 134 static int ptrace_child(void *arg) 135 { 136 int ret; 137 int pid = os_getpid(), ppid = getppid(); 138 int sc_result; 139 140 if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0){ 141 perror("ptrace"); 142 os_kill_process(pid, 0); 143 } 144 os_stop_process(pid); 145 146 /*This syscall will be intercepted by the parent. Don't call more than 147 * once, please.*/ 148 sc_result = os_getpid(); 149 150 if (sc_result == pid) 151 ret = 1; /*Nothing modified by the parent, we are running 152 normally.*/ 153 else if (sc_result == ppid) 154 ret = 0; /*Expected in check_ptrace and check_sysemu when they 155 succeed in modifying the stack frame*/ 156 else 157 ret = 2; /*Serious trouble! This could be caused by a bug in 158 host 2.6 SKAS3/2.6 patch before release -V6, together 159 with a bug in the UML code itself.*/ 160 _exit(ret); 161 } 162 163 static int start_ptraced_child(void **stack_out) 164 { 165 void *stack; 166 unsigned long sp; 167 int pid, n, status; 168 169 stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC, 170 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); 171 if(stack == MAP_FAILED) 172 panic("check_ptrace : mmap failed, errno = %d", errno); 173 sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *); 174 pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL); 175 if(pid < 0) 176 panic("check_ptrace : clone failed, errno = %d", errno); 177 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 178 if(n < 0) 179 panic("check_ptrace : wait failed, errno = %d", errno); 180 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) 181 panic("check_ptrace : expected SIGSTOP, got status = %d", 182 status); 183 184 *stack_out = stack; 185 return(pid); 186 } 187 188 /* When testing for SYSEMU support, if it is one of the broken versions, we must 189 * just avoid using sysemu, not panic, but only if SYSEMU features are broken. 190 * So only for SYSEMU features we test mustpanic, while normal host features 191 * must work anyway!*/ 192 static int stop_ptraced_child(int pid, void *stack, int exitcode, int mustpanic) 193 { 194 int status, n, ret = 0; 195 196 if(ptrace(PTRACE_CONT, pid, 0, 0) < 0) 197 panic("check_ptrace : ptrace failed, errno = %d", errno); 198 CATCH_EINTR(n = waitpid(pid, &status, 0)); 199 if(!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) { 200 int exit_with = WEXITSTATUS(status); 201 if (exit_with == 2) 202 printk("check_ptrace : child exited with status 2. " 203 "Serious trouble happening! Try updating your " 204 "host skas patch!\nDisabling SYSEMU support."); 205 printk("check_ptrace : child exited with exitcode %d, while " 206 "expecting %d; status 0x%x", exit_with, 207 exitcode, status); 208 if (mustpanic) 209 panic("\n"); 210 else 211 printk("\n"); 212 ret = -1; 213 } 214 215 if(munmap(stack, PAGE_SIZE) < 0) 216 panic("check_ptrace : munmap failed, errno = %d", errno); 217 return ret; 218 } 219 220 static int force_sysemu_disabled = 0; 221 222 int ptrace_faultinfo = 1; 223 int proc_mm = 1; 224 225 static int __init skas0_cmd_param(char *str, int* add) 226 { 227 ptrace_faultinfo = proc_mm = 0; 228 return 0; 229 } 230 231 static int __init nosysemu_cmd_param(char *str, int* add) 232 { 233 force_sysemu_disabled = 1; 234 return 0; 235 } 236 237 __uml_setup("skas0", skas0_cmd_param, 238 "skas0\n" 239 " Disables SKAS3 usage, so that SKAS0 is used, unless you \n" 240 " specify mode=tt.\n\n"); 241 242 __uml_setup("nosysemu", nosysemu_cmd_param, 243 "nosysemu\n" 244 " Turns off syscall emulation patch for ptrace (SYSEMU) on.\n" 245 " SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n" 246 " behaviour of ptrace() and helps reducing host context switch rate.\n" 247 " To make it working, you need a kernel patch for your host, too.\n" 248 " See http://perso.wanadoo.fr/laurent.vivier/UML/ for further information.\n\n"); 249 250 static void __init check_sysemu(void) 251 { 252 void *stack; 253 int pid, syscall, n, status, count=0; 254 255 printk("Checking syscall emulation patch for ptrace..."); 256 sysemu_supported = 0; 257 pid = start_ptraced_child(&stack); 258 259 if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0) 260 goto fail; 261 262 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 263 if (n < 0) 264 panic("check_sysemu : wait failed, errno = %d", errno); 265 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP)) 266 panic("check_sysemu : expected SIGTRAP, " 267 "got status = %d", status); 268 269 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, 270 os_getpid()); 271 if(n < 0) 272 panic("check_sysemu : failed to modify system " 273 "call return, errno = %d", errno); 274 275 if (stop_ptraced_child(pid, stack, 0, 0) < 0) 276 goto fail_stopped; 277 278 sysemu_supported = 1; 279 printk("OK\n"); 280 set_using_sysemu(!force_sysemu_disabled); 281 282 printk("Checking advanced syscall emulation patch for ptrace..."); 283 pid = start_ptraced_child(&stack); 284 while(1){ 285 count++; 286 if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0) 287 goto fail; 288 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 289 if(n < 0) 290 panic("check_ptrace : wait failed, errno = %d", errno); 291 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP)) 292 panic("check_ptrace : expected (SIGTRAP|SYSCALL_TRAP), " 293 "got status = %d", status); 294 295 syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET, 296 0); 297 if(syscall == __NR_getpid){ 298 if (!count) 299 panic("check_ptrace : SYSEMU_SINGLESTEP doesn't singlestep"); 300 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, 301 os_getpid()); 302 if(n < 0) 303 panic("check_sysemu : failed to modify system " 304 "call return, errno = %d", errno); 305 break; 306 } 307 } 308 if (stop_ptraced_child(pid, stack, 0, 0) < 0) 309 goto fail_stopped; 310 311 sysemu_supported = 2; 312 printk("OK\n"); 313 314 if ( !force_sysemu_disabled ) 315 set_using_sysemu(sysemu_supported); 316 return; 317 318 fail: 319 stop_ptraced_child(pid, stack, 1, 0); 320 fail_stopped: 321 printk("missing\n"); 322 } 323 324 void __init check_ptrace(void) 325 { 326 void *stack; 327 int pid, syscall, n, status; 328 329 printk("Checking that ptrace can change system call numbers..."); 330 pid = start_ptraced_child(&stack); 331 332 if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0) 333 panic("check_ptrace: PTRACE_SETOPTIONS failed, errno = %d", errno); 334 335 while(1){ 336 if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0) 337 panic("check_ptrace : ptrace failed, errno = %d", 338 errno); 339 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 340 if(n < 0) 341 panic("check_ptrace : wait failed, errno = %d", errno); 342 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP + 0x80)) 343 panic("check_ptrace : expected SIGTRAP + 0x80, " 344 "got status = %d", status); 345 346 syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET, 347 0); 348 if(syscall == __NR_getpid){ 349 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET, 350 __NR_getppid); 351 if(n < 0) 352 panic("check_ptrace : failed to modify system " 353 "call, errno = %d", errno); 354 break; 355 } 356 } 357 stop_ptraced_child(pid, stack, 0, 1); 358 printk("OK\n"); 359 check_sysemu(); 360 } 361 362 int run_kernel_thread(int (*fn)(void *), void *arg, void **jmp_ptr) 363 { 364 sigjmp_buf buf; 365 int n; 366 367 *jmp_ptr = &buf; 368 n = sigsetjmp(buf, 1); 369 if(n != 0) 370 return(n); 371 (*fn)(arg); 372 return(0); 373 } 374 375 void forward_pending_sigio(int target) 376 { 377 sigset_t sigs; 378 379 if(sigpending(&sigs)) 380 panic("forward_pending_sigio : sigpending failed"); 381 if(sigismember(&sigs, SIGIO)) 382 kill(target, SIGIO); 383 } 384 385 extern void *__syscall_stub_start, __syscall_stub_end; 386 387 #ifdef UML_CONFIG_MODE_SKAS 388 389 static inline void check_skas3_ptrace_support(void) 390 { 391 struct ptrace_faultinfo fi; 392 void *stack; 393 int pid, n; 394 395 printf("Checking for the skas3 patch in the host..."); 396 pid = start_ptraced_child(&stack); 397 398 n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi); 399 if (n < 0) { 400 ptrace_faultinfo = 0; 401 if(errno == EIO) 402 printf("not found\n"); 403 else { 404 perror("not found"); 405 } 406 } 407 else { 408 if (!ptrace_faultinfo) 409 printf("found but disabled on command line\n"); 410 else 411 printf("found\n"); 412 } 413 414 init_registers(pid); 415 stop_ptraced_child(pid, stack, 1, 1); 416 } 417 418 int can_do_skas(void) 419 { 420 printf("Checking for /proc/mm..."); 421 if (os_access("/proc/mm", OS_ACC_W_OK) < 0) { 422 proc_mm = 0; 423 printf("not found\n"); 424 } else { 425 if (!proc_mm) 426 printf("found but disabled on command line\n"); 427 else 428 printf("found\n"); 429 } 430 431 check_skas3_ptrace_support(); 432 return 1; 433 } 434 #else 435 int can_do_skas(void) 436 { 437 return(0); 438 } 439 #endif 440