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(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 static int __init nosysemu_cmd_param(char *str, int* add) 223 { 224 force_sysemu_disabled = 1; 225 return 0; 226 } 227 228 __uml_setup("nosysemu", nosysemu_cmd_param, 229 "nosysemu\n" 230 " Turns off syscall emulation patch for ptrace (SYSEMU) on.\n" 231 " SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n" 232 " behaviour of ptrace() and helps reducing host context switch rate.\n" 233 " To make it working, you need a kernel patch for your host, too.\n" 234 " See http://perso.wanadoo.fr/laurent.vivier/UML/ for further information.\n\n"); 235 236 static void __init check_sysemu(void) 237 { 238 void *stack; 239 int pid, syscall, n, status, count=0; 240 241 printk("Checking syscall emulation patch for ptrace..."); 242 sysemu_supported = 0; 243 pid = start_ptraced_child(&stack); 244 245 if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0) 246 goto fail; 247 248 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 249 if (n < 0) 250 panic("check_sysemu : wait failed, errno = %d", errno); 251 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP)) 252 panic("check_sysemu : expected SIGTRAP, " 253 "got status = %d", status); 254 255 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, 256 os_getpid()); 257 if(n < 0) 258 panic("check_sysemu : failed to modify system " 259 "call return, errno = %d", errno); 260 261 if (stop_ptraced_child(pid, stack, 0, 0) < 0) 262 goto fail_stopped; 263 264 sysemu_supported = 1; 265 printk("OK\n"); 266 set_using_sysemu(!force_sysemu_disabled); 267 268 printk("Checking advanced syscall emulation patch for ptrace..."); 269 pid = start_ptraced_child(&stack); 270 while(1){ 271 count++; 272 if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0) 273 goto fail; 274 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 275 if(n < 0) 276 panic("check_ptrace : wait failed, errno = %d", errno); 277 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP)) 278 panic("check_ptrace : expected (SIGTRAP|SYSCALL_TRAP), " 279 "got status = %d", status); 280 281 syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET, 282 0); 283 if(syscall == __NR_getpid){ 284 if (!count) 285 panic("check_ptrace : SYSEMU_SINGLESTEP doesn't singlestep"); 286 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, 287 os_getpid()); 288 if(n < 0) 289 panic("check_sysemu : failed to modify system " 290 "call return, errno = %d", errno); 291 break; 292 } 293 } 294 if (stop_ptraced_child(pid, stack, 0, 0) < 0) 295 goto fail_stopped; 296 297 sysemu_supported = 2; 298 printk("OK\n"); 299 300 if ( !force_sysemu_disabled ) 301 set_using_sysemu(sysemu_supported); 302 return; 303 304 fail: 305 stop_ptraced_child(pid, stack, 1, 0); 306 fail_stopped: 307 printk("missing\n"); 308 } 309 310 void __init check_ptrace(void) 311 { 312 void *stack; 313 int pid, syscall, n, status; 314 315 printk("Checking that ptrace can change system call numbers..."); 316 pid = start_ptraced_child(&stack); 317 318 if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0) 319 panic("check_ptrace: PTRACE_SETOPTIONS failed, errno = %d", errno); 320 321 while(1){ 322 if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0) 323 panic("check_ptrace : ptrace failed, errno = %d", 324 errno); 325 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 326 if(n < 0) 327 panic("check_ptrace : wait failed, errno = %d", errno); 328 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP + 0x80)) 329 panic("check_ptrace : expected SIGTRAP + 0x80, " 330 "got status = %d", status); 331 332 syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET, 333 0); 334 if(syscall == __NR_getpid){ 335 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET, 336 __NR_getppid); 337 if(n < 0) 338 panic("check_ptrace : failed to modify system " 339 "call, errno = %d", errno); 340 break; 341 } 342 } 343 stop_ptraced_child(pid, stack, 0, 1); 344 printk("OK\n"); 345 check_sysemu(); 346 } 347 348 int run_kernel_thread(int (*fn)(void *), void *arg, void **jmp_ptr) 349 { 350 sigjmp_buf buf; 351 int n; 352 353 *jmp_ptr = &buf; 354 n = sigsetjmp(buf, 1); 355 if(n != 0) 356 return(n); 357 (*fn)(arg); 358 return(0); 359 } 360 361 void forward_pending_sigio(int target) 362 { 363 sigset_t sigs; 364 365 if(sigpending(&sigs)) 366 panic("forward_pending_sigio : sigpending failed"); 367 if(sigismember(&sigs, SIGIO)) 368 kill(target, SIGIO); 369 } 370 371 #ifdef UML_CONFIG_MODE_SKAS 372 static inline int check_skas3_ptrace_support(void) 373 { 374 struct ptrace_faultinfo fi; 375 void *stack; 376 int pid, n, ret = 1; 377 378 printf("Checking for the skas3 patch in the host..."); 379 pid = start_ptraced_child(&stack); 380 381 n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi); 382 if (n < 0) { 383 if(errno == EIO) 384 printf("not found\n"); 385 else { 386 perror("not found"); 387 } 388 ret = 0; 389 } else { 390 printf("found\n"); 391 } 392 393 init_registers(pid); 394 stop_ptraced_child(pid, stack, 1, 1); 395 396 return(ret); 397 } 398 399 int can_do_skas(void) 400 { 401 int ret = 1; 402 403 printf("Checking for /proc/mm..."); 404 if (os_access("/proc/mm", OS_ACC_W_OK) < 0) { 405 printf("not found\n"); 406 ret = 0; 407 goto out; 408 } else { 409 printf("found\n"); 410 } 411 412 ret = check_skas3_ptrace_support(); 413 out: 414 return ret; 415 } 416 #else 417 int can_do_skas(void) 418 { 419 return(0); 420 } 421 #endif 422