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) 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) 163 { 164 int pid, n, status; 165 166 pid = fork(); 167 if(pid == 0) 168 ptrace_child(); 169 170 if(pid < 0) 171 panic("check_ptrace : fork failed, errno = %d", errno); 172 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 173 if(n < 0) 174 panic("check_ptrace : wait failed, errno = %d", errno); 175 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) 176 panic("check_ptrace : expected SIGSTOP, got status = %d", 177 status); 178 179 return(pid); 180 } 181 182 /* When testing for SYSEMU support, if it is one of the broken versions, we must 183 * just avoid using sysemu, not panic, but only if SYSEMU features are broken. 184 * So only for SYSEMU features we test mustpanic, while normal host features 185 * must work anyway!*/ 186 static int stop_ptraced_child(int pid, int exitcode, int mustexit) 187 { 188 int status, n, ret = 0; 189 190 if(ptrace(PTRACE_CONT, pid, 0, 0) < 0) 191 panic("stop_ptraced_child : ptrace failed, errno = %d", errno); 192 CATCH_EINTR(n = waitpid(pid, &status, 0)); 193 if(!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) { 194 int exit_with = WEXITSTATUS(status); 195 if (exit_with == 2) 196 printk("check_ptrace : child exited with status 2. " 197 "Serious trouble happening! Try updating your " 198 "host skas patch!\nDisabling SYSEMU support."); 199 printk("check_ptrace : child exited with exitcode %d, while " 200 "expecting %d; status 0x%x", exit_with, 201 exitcode, status); 202 if (mustexit) 203 panic("\n"); 204 else 205 printk("\n"); 206 ret = -1; 207 } 208 209 return ret; 210 } 211 212 static int force_sysemu_disabled = 0; 213 214 static int __init nosysemu_cmd_param(char *str, int* add) 215 { 216 force_sysemu_disabled = 1; 217 return 0; 218 } 219 220 __uml_setup("nosysemu", nosysemu_cmd_param, 221 "nosysemu\n" 222 " Turns off syscall emulation patch for ptrace (SYSEMU) on.\n" 223 " SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n" 224 " behaviour of ptrace() and helps reducing host context switch rate.\n" 225 " To make it working, you need a kernel patch for your host, too.\n" 226 " See http://perso.wanadoo.fr/laurent.vivier/UML/ for further information.\n\n"); 227 228 static void __init check_sysemu(void) 229 { 230 int pid, syscall, n, status, count=0; 231 232 printk("Checking syscall emulation patch for ptrace..."); 233 sysemu_supported = 0; 234 pid = start_ptraced_child(); 235 236 if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0) 237 goto fail; 238 239 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 240 if (n < 0) 241 panic("check_sysemu : wait failed, errno = %d", errno); 242 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP)) 243 panic("check_sysemu : expected SIGTRAP, " 244 "got status = %d", status); 245 246 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, 247 os_getpid()); 248 if(n < 0) 249 panic("check_sysemu : failed to modify system " 250 "call return, errno = %d", errno); 251 252 if (stop_ptraced_child(pid, 0, 0) < 0) 253 goto fail_stopped; 254 255 sysemu_supported = 1; 256 printk("OK\n"); 257 set_using_sysemu(!force_sysemu_disabled); 258 259 printk("Checking advanced syscall emulation patch for ptrace..."); 260 pid = start_ptraced_child(); 261 while(1){ 262 count++; 263 if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0) 264 goto fail; 265 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 266 if(n < 0) 267 panic("check_ptrace : wait failed, errno = %d", errno); 268 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP)) 269 panic("check_ptrace : expected (SIGTRAP|SYSCALL_TRAP), " 270 "got status = %d", status); 271 272 syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET, 273 0); 274 if(syscall == __NR_getpid){ 275 if (!count) 276 panic("check_ptrace : SYSEMU_SINGLESTEP doesn't singlestep"); 277 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, 278 os_getpid()); 279 if(n < 0) 280 panic("check_sysemu : failed to modify system " 281 "call return, errno = %d", errno); 282 break; 283 } 284 } 285 if (stop_ptraced_child(pid, 0, 0) < 0) 286 goto fail_stopped; 287 288 sysemu_supported = 2; 289 printk("OK\n"); 290 291 if ( !force_sysemu_disabled ) 292 set_using_sysemu(sysemu_supported); 293 return; 294 295 fail: 296 stop_ptraced_child(pid, 1, 0); 297 fail_stopped: 298 printk("missing\n"); 299 } 300 301 void __init check_ptrace(void) 302 { 303 int pid, syscall, n, status; 304 305 printk("Checking that ptrace can change system call numbers..."); 306 pid = start_ptraced_child(); 307 308 if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0) 309 panic("check_ptrace: PTRACE_SETOPTIONS failed, errno = %d", errno); 310 311 while(1){ 312 if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0) 313 panic("check_ptrace : ptrace failed, errno = %d", 314 errno); 315 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 316 if(n < 0) 317 panic("check_ptrace : wait failed, errno = %d", errno); 318 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP + 0x80)) 319 panic("check_ptrace : expected SIGTRAP + 0x80, " 320 "got status = %d", status); 321 322 syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET, 323 0); 324 if(syscall == __NR_getpid){ 325 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET, 326 __NR_getppid); 327 if(n < 0) 328 panic("check_ptrace : failed to modify system " 329 "call, errno = %d", errno); 330 break; 331 } 332 } 333 stop_ptraced_child(pid, 0, 1); 334 printk("OK\n"); 335 check_sysemu(); 336 } 337 338 int run_kernel_thread(int (*fn)(void *), void *arg, void **jmp_ptr) 339 { 340 sigjmp_buf buf; 341 int n; 342 343 *jmp_ptr = &buf; 344 n = sigsetjmp(buf, 1); 345 if(n != 0) 346 return(n); 347 (*fn)(arg); 348 return(0); 349 } 350 351 void forward_pending_sigio(int target) 352 { 353 sigset_t sigs; 354 355 if(sigpending(&sigs)) 356 panic("forward_pending_sigio : sigpending failed"); 357 if(sigismember(&sigs, SIGIO)) 358 kill(target, SIGIO); 359 } 360 361 #ifdef UML_CONFIG_MODE_SKAS 362 static inline int check_skas3_ptrace_support(void) 363 { 364 struct ptrace_faultinfo fi; 365 int pid, n, ret = 1; 366 367 printf("Checking for the skas3 patch in the host..."); 368 pid = start_ptraced_child(); 369 370 n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi); 371 if (n < 0) { 372 if(errno == EIO) 373 printf("not found\n"); 374 else { 375 perror("not found"); 376 } 377 ret = 0; 378 } else { 379 printf("found\n"); 380 } 381 382 init_registers(pid); 383 stop_ptraced_child(pid, 1, 1); 384 385 return(ret); 386 } 387 388 int can_do_skas(void) 389 { 390 int ret = 1; 391 392 printf("Checking for /proc/mm..."); 393 if (os_access("/proc/mm", OS_ACC_W_OK) < 0) { 394 printf("not found\n"); 395 ret = 0; 396 goto out; 397 } else { 398 printf("found\n"); 399 } 400 401 ret = check_skas3_ptrace_support(); 402 out: 403 return ret; 404 } 405 #else 406 int can_do_skas(void) 407 { 408 return(0); 409 } 410 #endif 411