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) 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) 164 { 165 int pid, n, status; 166 167 pid = fork(); 168 if(pid == 0) 169 ptrace_child(); 170 171 if(pid < 0) 172 panic("check_ptrace : fork failed, errno = %d", errno); 173 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 174 if(n < 0) 175 panic("check_ptrace : wait failed, errno = %d", errno); 176 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) 177 panic("check_ptrace : expected SIGSTOP, got status = %d", 178 status); 179 180 return(pid); 181 } 182 183 /* When testing for SYSEMU support, if it is one of the broken versions, we must 184 * just avoid using sysemu, not panic, but only if SYSEMU features are broken. 185 * So only for SYSEMU features we test mustpanic, while normal host features 186 * must work anyway!*/ 187 static int stop_ptraced_child(int pid, int exitcode, int mustexit) 188 { 189 int status, n, ret = 0; 190 191 if(ptrace(PTRACE_CONT, pid, 0, 0) < 0) 192 panic("stop_ptraced_child : ptrace failed, errno = %d", errno); 193 CATCH_EINTR(n = waitpid(pid, &status, 0)); 194 if(!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) { 195 int exit_with = WEXITSTATUS(status); 196 if (exit_with == 2) 197 printk("check_ptrace : child exited with status 2. " 198 "Serious trouble happening! Try updating your " 199 "host skas patch!\nDisabling SYSEMU support."); 200 printk("check_ptrace : child exited with exitcode %d, while " 201 "expecting %d; status 0x%x", exit_with, 202 exitcode, status); 203 if (mustexit) 204 panic("\n"); 205 else 206 printk("\n"); 207 ret = -1; 208 } 209 210 return ret; 211 } 212 213 static int force_sysemu_disabled = 0; 214 215 static int __init nosysemu_cmd_param(char *str, int* add) 216 { 217 force_sysemu_disabled = 1; 218 return 0; 219 } 220 221 __uml_setup("nosysemu", nosysemu_cmd_param, 222 "nosysemu\n" 223 " Turns off syscall emulation patch for ptrace (SYSEMU) on.\n" 224 " SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n" 225 " behaviour of ptrace() and helps reducing host context switch rate.\n" 226 " To make it working, you need a kernel patch for your host, too.\n" 227 " See http://perso.wanadoo.fr/laurent.vivier/UML/ for further information.\n\n"); 228 229 static void __init check_sysemu(void) 230 { 231 int pid, syscall, n, status, count=0; 232 233 printk("Checking syscall emulation patch for ptrace..."); 234 sysemu_supported = 0; 235 pid = start_ptraced_child(); 236 237 if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0) 238 goto fail; 239 240 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 241 if (n < 0) 242 panic("check_sysemu : wait failed, errno = %d", errno); 243 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP)) 244 panic("check_sysemu : expected SIGTRAP, " 245 "got status = %d", status); 246 247 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, 248 os_getpid()); 249 if(n < 0) 250 panic("check_sysemu : failed to modify system " 251 "call return, errno = %d", errno); 252 253 if (stop_ptraced_child(pid, 0, 0) < 0) 254 goto fail_stopped; 255 256 sysemu_supported = 1; 257 printk("OK\n"); 258 set_using_sysemu(!force_sysemu_disabled); 259 260 printk("Checking advanced syscall emulation patch for ptrace..."); 261 pid = start_ptraced_child(); 262 while(1){ 263 count++; 264 if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0) 265 goto fail; 266 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 267 if(n < 0) 268 panic("check_ptrace : wait failed, errno = %d", errno); 269 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP)) 270 panic("check_ptrace : expected (SIGTRAP|SYSCALL_TRAP), " 271 "got status = %d", status); 272 273 syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET, 274 0); 275 if(syscall == __NR_getpid){ 276 if (!count) 277 panic("check_ptrace : SYSEMU_SINGLESTEP doesn't singlestep"); 278 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, 279 os_getpid()); 280 if(n < 0) 281 panic("check_sysemu : failed to modify system " 282 "call return, errno = %d", errno); 283 break; 284 } 285 } 286 if (stop_ptraced_child(pid, 0, 0) < 0) 287 goto fail_stopped; 288 289 sysemu_supported = 2; 290 printk("OK\n"); 291 292 if ( !force_sysemu_disabled ) 293 set_using_sysemu(sysemu_supported); 294 return; 295 296 fail: 297 stop_ptraced_child(pid, 1, 0); 298 fail_stopped: 299 printk("missing\n"); 300 } 301 302 void __init check_ptrace(void) 303 { 304 int pid, syscall, n, status; 305 306 printk("Checking that ptrace can change system call numbers..."); 307 pid = start_ptraced_child(); 308 309 if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0) 310 panic("check_ptrace: PTRACE_SETOPTIONS failed, errno = %d", errno); 311 312 while(1){ 313 if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0) 314 panic("check_ptrace : ptrace failed, errno = %d", 315 errno); 316 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 317 if(n < 0) 318 panic("check_ptrace : wait failed, errno = %d", errno); 319 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP + 0x80)) 320 panic("check_ptrace : expected SIGTRAP + 0x80, " 321 "got status = %d", status); 322 323 syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET, 324 0); 325 if(syscall == __NR_getpid){ 326 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET, 327 __NR_getppid); 328 if(n < 0) 329 panic("check_ptrace : failed to modify system " 330 "call, errno = %d", errno); 331 break; 332 } 333 } 334 stop_ptraced_child(pid, 0, 1); 335 printk("OK\n"); 336 check_sysemu(); 337 } 338 339 int run_kernel_thread(int (*fn)(void *), void *arg, void **jmp_ptr) 340 { 341 sigjmp_buf buf; 342 int n; 343 344 *jmp_ptr = &buf; 345 n = sigsetjmp(buf, 1); 346 if(n != 0) 347 return(n); 348 (*fn)(arg); 349 return(0); 350 } 351 352 void forward_pending_sigio(int target) 353 { 354 sigset_t sigs; 355 356 if(sigpending(&sigs)) 357 panic("forward_pending_sigio : sigpending failed"); 358 if(sigismember(&sigs, SIGIO)) 359 kill(target, SIGIO); 360 } 361 362 int ptrace_faultinfo = 0; 363 int proc_mm = 1; 364 365 extern void *__syscall_stub_start, __syscall_stub_end; 366 367 #ifdef UML_CONFIG_MODE_SKAS 368 static inline void check_skas3_ptrace_support(void) 369 { 370 struct ptrace_faultinfo fi; 371 int pid, n; 372 373 printf("Checking for the skas3 patch in the host..."); 374 pid = start_ptraced_child(); 375 376 n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi); 377 if (n < 0) { 378 if(errno == EIO) 379 printf("not found\n"); 380 else { 381 perror("not found"); 382 } 383 } 384 else { 385 ptrace_faultinfo = 1; 386 printf("found\n"); 387 } 388 389 init_registers(pid); 390 stop_ptraced_child(pid, 1, 1); 391 } 392 393 int can_do_skas(void) 394 { 395 printf("Checking for /proc/mm..."); 396 if (os_access("/proc/mm", OS_ACC_W_OK) < 0) { 397 proc_mm = 0; 398 printf("not found\n"); 399 goto out; 400 } 401 else { 402 printf("found\n"); 403 } 404 405 out: 406 check_skas3_ptrace_support(); 407 return 1; 408 } 409 #else 410 int can_do_skas(void) 411 { 412 return(0); 413 } 414 #endif 415