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 424