1 /* 2 * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com) 3 * Licensed under the GPL 4 */ 5 6 #include <pty.h> 7 #include <stdio.h> 8 #include <stddef.h> 9 #include <stdarg.h> 10 #include <stdlib.h> 11 #include <string.h> 12 #include <unistd.h> 13 #include <signal.h> 14 #include <sched.h> 15 #include <fcntl.h> 16 #include <errno.h> 17 #include <sys/time.h> 18 #include <sys/wait.h> 19 #include <sys/mman.h> 20 #include <sys/resource.h> 21 #include <asm/unistd.h> 22 #include <asm/page.h> 23 #include <sys/types.h> 24 #include "kern_util.h" 25 #include "user.h" 26 #include "signal_kern.h" 27 #include "sysdep/ptrace.h" 28 #include "sysdep/sigcontext.h" 29 #include "irq_user.h" 30 #include "ptrace_user.h" 31 #include "mem_user.h" 32 #include "init.h" 33 #include "os.h" 34 #include "uml-config.h" 35 #include "choose-mode.h" 36 #include "mode.h" 37 #include "tempfile.h" 38 #include "kern_constants.h" 39 40 #ifdef UML_CONFIG_MODE_SKAS 41 #include "skas.h" 42 #include "skas_ptrace.h" 43 #include "registers.h" 44 #endif 45 46 static int ptrace_child(void *arg) 47 { 48 int ret; 49 int pid = os_getpid(), ppid = getppid(); 50 int sc_result; 51 52 change_sig(SIGWINCH, 0); 53 if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0){ 54 perror("ptrace"); 55 os_kill_process(pid, 0); 56 } 57 kill(pid, SIGSTOP); 58 59 /*This syscall will be intercepted by the parent. Don't call more than 60 * once, please.*/ 61 sc_result = os_getpid(); 62 63 if (sc_result == pid) 64 ret = 1; /*Nothing modified by the parent, we are running 65 normally.*/ 66 else if (sc_result == ppid) 67 ret = 0; /*Expected in check_ptrace and check_sysemu when they 68 succeed in modifying the stack frame*/ 69 else 70 ret = 2; /*Serious trouble! This could be caused by a bug in 71 host 2.6 SKAS3/2.6 patch before release -V6, together 72 with a bug in the UML code itself.*/ 73 _exit(ret); 74 } 75 76 static void fatal_perror(char *str) 77 { 78 perror(str); 79 exit(1); 80 } 81 82 static void fatal(char *fmt, ...) 83 { 84 va_list list; 85 86 va_start(list, fmt); 87 vprintf(fmt, list); 88 va_end(list); 89 fflush(stdout); 90 91 exit(1); 92 } 93 94 static void non_fatal(char *fmt, ...) 95 { 96 va_list list; 97 98 va_start(list, fmt); 99 vprintf(fmt, list); 100 va_end(list); 101 fflush(stdout); 102 } 103 104 static int start_ptraced_child(void **stack_out) 105 { 106 void *stack; 107 unsigned long sp; 108 int pid, n, status; 109 110 stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC, 111 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); 112 if(stack == MAP_FAILED) 113 fatal_perror("check_ptrace : mmap failed"); 114 sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *); 115 pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL); 116 if(pid < 0) 117 fatal_perror("start_ptraced_child : clone failed"); 118 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 119 if(n < 0) 120 fatal_perror("check_ptrace : clone failed"); 121 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) 122 fatal("check_ptrace : expected SIGSTOP, got status = %d", 123 status); 124 125 *stack_out = stack; 126 return pid; 127 } 128 129 /* When testing for SYSEMU support, if it is one of the broken versions, we 130 * must just avoid using sysemu, not panic, but only if SYSEMU features are 131 * broken. 132 * So only for SYSEMU features we test mustpanic, while normal host features 133 * must work anyway! 134 */ 135 static int stop_ptraced_child(int pid, void *stack, int exitcode, 136 int mustexit) 137 { 138 int status, n, ret = 0; 139 140 if(ptrace(PTRACE_CONT, pid, 0, 0) < 0) 141 fatal_perror("stop_ptraced_child : ptrace failed"); 142 CATCH_EINTR(n = waitpid(pid, &status, 0)); 143 if(!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) { 144 int exit_with = WEXITSTATUS(status); 145 if (exit_with == 2) 146 non_fatal("check_ptrace : child exited with status 2. " 147 "Serious trouble happening! Try updating " 148 "your host skas patch!\nDisabling SYSEMU " 149 "support."); 150 non_fatal("check_ptrace : child exited with exitcode %d, while " 151 "expecting %d; status 0x%x\n", exit_with, 152 exitcode, status); 153 if (mustexit) 154 exit(1); 155 ret = -1; 156 } 157 158 if(munmap(stack, PAGE_SIZE) < 0) 159 fatal_perror("check_ptrace : munmap failed"); 160 return ret; 161 } 162 163 /* Changed only during early boot */ 164 int ptrace_faultinfo = 1; 165 int ptrace_ldt = 1; 166 int proc_mm = 1; 167 int skas_needs_stub = 0; 168 169 static int __init skas0_cmd_param(char *str, int* add) 170 { 171 ptrace_faultinfo = proc_mm = 0; 172 return 0; 173 } 174 175 /* The two __uml_setup would conflict, without this stupid alias. */ 176 177 static int __init mode_skas0_cmd_param(char *str, int* add) 178 __attribute__((alias("skas0_cmd_param"))); 179 180 __uml_setup("skas0", skas0_cmd_param, 181 "skas0\n" 182 " Disables SKAS3 usage, so that SKAS0 is used, unless \n" 183 " you specify mode=tt.\n\n"); 184 185 __uml_setup("mode=skas0", mode_skas0_cmd_param, 186 "mode=skas0\n" 187 " Disables SKAS3 usage, so that SKAS0 is used, unless you \n" 188 " specify mode=tt. Note that this was recently added - on \n" 189 " older kernels you must use simply \"skas0\".\n\n"); 190 191 /* Changed only during early boot */ 192 static int force_sysemu_disabled = 0; 193 194 static int __init nosysemu_cmd_param(char *str, int* add) 195 { 196 force_sysemu_disabled = 1; 197 return 0; 198 } 199 200 __uml_setup("nosysemu", nosysemu_cmd_param, 201 "nosysemu\n" 202 " Turns off syscall emulation patch for ptrace (SYSEMU) on.\n" 203 " SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n" 204 " behaviour of ptrace() and helps reducing host context switch rate.\n" 205 " To make it working, you need a kernel patch for your host, too.\n" 206 " See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n" 207 " information.\n\n"); 208 209 static void __init check_sysemu(void) 210 { 211 void *stack; 212 int pid, n, status, count=0; 213 214 non_fatal("Checking syscall emulation patch for ptrace..."); 215 sysemu_supported = 0; 216 pid = start_ptraced_child(&stack); 217 218 if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0) 219 goto fail; 220 221 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 222 if (n < 0) 223 fatal_perror("check_sysemu : wait failed"); 224 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP)) 225 fatal("check_sysemu : expected SIGTRAP, got status = %d", 226 status); 227 228 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, 229 os_getpid()); 230 if(n < 0) 231 fatal_perror("check_sysemu : failed to modify system call " 232 "return"); 233 234 if (stop_ptraced_child(pid, stack, 0, 0) < 0) 235 goto fail_stopped; 236 237 sysemu_supported = 1; 238 non_fatal("OK\n"); 239 set_using_sysemu(!force_sysemu_disabled); 240 241 non_fatal("Checking advanced syscall emulation patch for ptrace..."); 242 pid = start_ptraced_child(&stack); 243 244 if((ptrace(PTRACE_OLDSETOPTIONS, pid, 0, 245 (void *) PTRACE_O_TRACESYSGOOD) < 0)) 246 fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed"); 247 248 while(1){ 249 count++; 250 if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0) 251 goto fail; 252 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 253 if(n < 0) 254 fatal_perror("check_ptrace : wait failed"); 255 256 if(WIFSTOPPED(status) && (WSTOPSIG(status) == (SIGTRAP|0x80))){ 257 if (!count) 258 fatal("check_ptrace : SYSEMU_SINGLESTEP " 259 "doesn't singlestep"); 260 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, 261 os_getpid()); 262 if(n < 0) 263 fatal_perror("check_sysemu : failed to modify " 264 "system call return"); 265 break; 266 } 267 else if(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP)) 268 count++; 269 else 270 fatal("check_ptrace : expected SIGTRAP or " 271 "(SIGTRAP | 0x80), got status = %d", status); 272 } 273 if (stop_ptraced_child(pid, stack, 0, 0) < 0) 274 goto fail_stopped; 275 276 sysemu_supported = 2; 277 non_fatal("OK\n"); 278 279 if ( !force_sysemu_disabled ) 280 set_using_sysemu(sysemu_supported); 281 return; 282 283 fail: 284 stop_ptraced_child(pid, stack, 1, 0); 285 fail_stopped: 286 non_fatal("missing\n"); 287 } 288 289 static void __init check_ptrace(void) 290 { 291 void *stack; 292 int pid, syscall, n, status; 293 294 non_fatal("Checking that ptrace can change system call numbers..."); 295 pid = start_ptraced_child(&stack); 296 297 if((ptrace(PTRACE_OLDSETOPTIONS, pid, 0, 298 (void *) PTRACE_O_TRACESYSGOOD) < 0)) 299 fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed"); 300 301 while(1){ 302 if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0) 303 fatal_perror("check_ptrace : ptrace failed"); 304 305 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 306 if(n < 0) 307 fatal_perror("check_ptrace : wait failed"); 308 309 if(!WIFSTOPPED(status) || 310 (WSTOPSIG(status) != (SIGTRAP | 0x80))) 311 fatal("check_ptrace : expected (SIGTRAP|0x80), " 312 "got status = %d", status); 313 314 syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET, 315 0); 316 if(syscall == __NR_getpid){ 317 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET, 318 __NR_getppid); 319 if(n < 0) 320 fatal_perror("check_ptrace : failed to modify " 321 "system call"); 322 break; 323 } 324 } 325 stop_ptraced_child(pid, stack, 0, 1); 326 non_fatal("OK\n"); 327 check_sysemu(); 328 } 329 330 extern void check_tmpexec(void); 331 332 static void __init check_coredump_limit(void) 333 { 334 struct rlimit lim; 335 int err = getrlimit(RLIMIT_CORE, &lim); 336 337 if(err){ 338 perror("Getting core dump limit"); 339 return; 340 } 341 342 printf("Core dump limits :\n\tsoft - "); 343 if(lim.rlim_cur == RLIM_INFINITY) 344 printf("NONE\n"); 345 else printf("%lu\n", lim.rlim_cur); 346 347 printf("\thard - "); 348 if(lim.rlim_max == RLIM_INFINITY) 349 printf("NONE\n"); 350 else printf("%lu\n", lim.rlim_max); 351 } 352 353 void __init os_early_checks(void) 354 { 355 /* Print out the core dump limits early */ 356 check_coredump_limit(); 357 358 check_ptrace(); 359 360 /* Need to check this early because mmapping happens before the 361 * kernel is running. 362 */ 363 check_tmpexec(); 364 } 365 366 static int __init noprocmm_cmd_param(char *str, int* add) 367 { 368 proc_mm = 0; 369 return 0; 370 } 371 372 __uml_setup("noprocmm", noprocmm_cmd_param, 373 "noprocmm\n" 374 " Turns off usage of /proc/mm, even if host supports it.\n" 375 " To support /proc/mm, the host needs to be patched using\n" 376 " the current skas3 patch.\n\n"); 377 378 static int __init noptracefaultinfo_cmd_param(char *str, int* add) 379 { 380 ptrace_faultinfo = 0; 381 return 0; 382 } 383 384 __uml_setup("noptracefaultinfo", noptracefaultinfo_cmd_param, 385 "noptracefaultinfo\n" 386 " Turns off usage of PTRACE_FAULTINFO, even if host supports\n" 387 " it. To support PTRACE_FAULTINFO, the host needs to be patched\n" 388 " using the current skas3 patch.\n\n"); 389 390 static int __init noptraceldt_cmd_param(char *str, int* add) 391 { 392 ptrace_ldt = 0; 393 return 0; 394 } 395 396 __uml_setup("noptraceldt", noptraceldt_cmd_param, 397 "noptraceldt\n" 398 " Turns off usage of PTRACE_LDT, even if host supports it.\n" 399 " To support PTRACE_LDT, the host needs to be patched using\n" 400 " the current skas3 patch.\n\n"); 401 402 #ifdef UML_CONFIG_MODE_SKAS 403 static inline void check_skas3_ptrace_faultinfo(void) 404 { 405 struct ptrace_faultinfo fi; 406 void *stack; 407 int pid, n; 408 409 non_fatal(" - PTRACE_FAULTINFO..."); 410 pid = start_ptraced_child(&stack); 411 412 n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi); 413 if (n < 0) { 414 ptrace_faultinfo = 0; 415 if(errno == EIO) 416 non_fatal("not found\n"); 417 else 418 perror("not found"); 419 } 420 else { 421 if (!ptrace_faultinfo) 422 non_fatal("found but disabled on command line\n"); 423 else 424 non_fatal("found\n"); 425 } 426 427 init_registers(pid); 428 stop_ptraced_child(pid, stack, 1, 1); 429 } 430 431 static inline void check_skas3_ptrace_ldt(void) 432 { 433 #ifdef PTRACE_LDT 434 void *stack; 435 int pid, n; 436 unsigned char ldtbuf[40]; 437 struct ptrace_ldt ldt_op = (struct ptrace_ldt) { 438 .func = 2, /* read default ldt */ 439 .ptr = ldtbuf, 440 .bytecount = sizeof(ldtbuf)}; 441 442 non_fatal(" - PTRACE_LDT..."); 443 pid = start_ptraced_child(&stack); 444 445 n = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op); 446 if (n < 0) { 447 if(errno == EIO) 448 non_fatal("not found\n"); 449 else { 450 perror("not found"); 451 } 452 ptrace_ldt = 0; 453 } 454 else { 455 if(ptrace_ldt) 456 non_fatal("found\n"); 457 else 458 non_fatal("found, but use is disabled\n"); 459 } 460 461 stop_ptraced_child(pid, stack, 1, 1); 462 #else 463 /* PTRACE_LDT might be disabled via cmdline option. 464 * We want to override this, else we might use the stub 465 * without real need 466 */ 467 ptrace_ldt = 1; 468 #endif 469 } 470 471 static inline void check_skas3_proc_mm(void) 472 { 473 non_fatal(" - /proc/mm..."); 474 if (access("/proc/mm", W_OK) < 0) { 475 proc_mm = 0; 476 perror("not found"); 477 } 478 else { 479 if (!proc_mm) 480 non_fatal("found but disabled on command line\n"); 481 else 482 non_fatal("found\n"); 483 } 484 } 485 486 int can_do_skas(void) 487 { 488 non_fatal("Checking for the skas3 patch in the host:\n"); 489 490 check_skas3_proc_mm(); 491 check_skas3_ptrace_faultinfo(); 492 check_skas3_ptrace_ldt(); 493 494 if(!proc_mm || !ptrace_faultinfo || !ptrace_ldt) 495 skas_needs_stub = 1; 496 497 return 1; 498 } 499 #else 500 int can_do_skas(void) 501 { 502 return 0; 503 } 504 #endif 505 506 int __init parse_iomem(char *str, int *add) 507 { 508 struct iomem_region *new; 509 struct stat64 buf; 510 char *file, *driver; 511 int fd, size; 512 513 driver = str; 514 file = strchr(str,','); 515 if(file == NULL){ 516 printf("parse_iomem : failed to parse iomem\n"); 517 goto out; 518 } 519 *file = '\0'; 520 file++; 521 fd = open(file, O_RDWR, 0); 522 if(fd < 0){ 523 os_print_error(fd, "parse_iomem - Couldn't open io file"); 524 goto out; 525 } 526 527 if(fstat64(fd, &buf) < 0){ 528 perror("parse_iomem - cannot stat_fd file"); 529 goto out_close; 530 } 531 532 new = malloc(sizeof(*new)); 533 if(new == NULL){ 534 perror("Couldn't allocate iomem_region struct"); 535 goto out_close; 536 } 537 538 size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1); 539 540 *new = ((struct iomem_region) { .next = iomem_regions, 541 .driver = driver, 542 .fd = fd, 543 .size = size, 544 .phys = 0, 545 .virt = 0 }); 546 iomem_regions = new; 547 iomem_size += new->size + UM_KERN_PAGE_SIZE; 548 549 return 0; 550 out_close: 551 close(fd); 552 out: 553 return 1; 554 } 555