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