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, UM_KERN_PAGE_SIZE, 111 PROT_READ | PROT_WRITE | PROT_EXEC, 112 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); 113 if(stack == MAP_FAILED) 114 fatal_perror("check_ptrace : mmap failed"); 115 sp = (unsigned long) stack + UM_KERN_PAGE_SIZE - sizeof(void *); 116 pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL); 117 if(pid < 0) 118 fatal_perror("start_ptraced_child : clone failed"); 119 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 120 if(n < 0) 121 fatal_perror("check_ptrace : clone failed"); 122 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) 123 fatal("check_ptrace : expected SIGSTOP, got status = %d", 124 status); 125 126 *stack_out = stack; 127 return pid; 128 } 129 130 /* When testing for SYSEMU support, if it is one of the broken versions, we 131 * must just avoid using sysemu, not panic, but only if SYSEMU features are 132 * broken. 133 * So only for SYSEMU features we test mustpanic, while normal host features 134 * must work anyway! 135 */ 136 static int stop_ptraced_child(int pid, void *stack, int exitcode, 137 int mustexit) 138 { 139 int status, n, ret = 0; 140 141 if(ptrace(PTRACE_CONT, pid, 0, 0) < 0) 142 fatal_perror("stop_ptraced_child : ptrace failed"); 143 CATCH_EINTR(n = waitpid(pid, &status, 0)); 144 if(!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) { 145 int exit_with = WEXITSTATUS(status); 146 if (exit_with == 2) 147 non_fatal("check_ptrace : child exited with status 2. " 148 "\nDisabling SYSEMU support.\n"); 149 non_fatal("check_ptrace : child exited with exitcode %d, while " 150 "expecting %d; status 0x%x\n", exit_with, 151 exitcode, status); 152 if (mustexit) 153 exit(1); 154 ret = -1; 155 } 156 157 if(munmap(stack, UM_KERN_PAGE_SIZE) < 0) 158 fatal_perror("check_ptrace : munmap failed"); 159 return ret; 160 } 161 162 /* Changed only during early boot */ 163 int ptrace_faultinfo = 1; 164 int ptrace_ldt = 1; 165 int proc_mm = 1; 166 int skas_needs_stub = 0; 167 168 static int __init skas0_cmd_param(char *str, int* add) 169 { 170 ptrace_faultinfo = proc_mm = 0; 171 return 0; 172 } 173 174 /* The two __uml_setup would conflict, without this stupid alias. */ 175 176 static int __init mode_skas0_cmd_param(char *str, int* add) 177 __attribute__((alias("skas0_cmd_param"))); 178 179 __uml_setup("skas0", skas0_cmd_param, 180 "skas0\n" 181 " Disables SKAS3 usage, so that SKAS0 is used, unless \n" 182 " you specify mode=tt.\n\n"); 183 184 __uml_setup("mode=skas0", mode_skas0_cmd_param, 185 "mode=skas0\n" 186 " Disables SKAS3 usage, so that SKAS0 is used, unless you \n" 187 " specify mode=tt. Note that this was recently added - on \n" 188 " older kernels you must use simply \"skas0\".\n\n"); 189 190 /* Changed only during early boot */ 191 static int force_sysemu_disabled = 0; 192 193 static int __init nosysemu_cmd_param(char *str, int* add) 194 { 195 force_sysemu_disabled = 1; 196 return 0; 197 } 198 199 __uml_setup("nosysemu", nosysemu_cmd_param, 200 "nosysemu\n" 201 " Turns off syscall emulation patch for ptrace (SYSEMU) on.\n" 202 " SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n" 203 " behaviour of ptrace() and helps reducing host context switch rate.\n" 204 " To make it working, you need a kernel patch for your host, too.\n" 205 " See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n" 206 " information.\n\n"); 207 208 static void __init check_sysemu(void) 209 { 210 void *stack; 211 unsigned long regs[MAX_REG_NR]; 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 if(ptrace(PTRACE_GETREGS, pid, 0, regs) < 0) 229 fatal_perror("check_sysemu : PTRACE_GETREGS failed"); 230 if(PT_SYSCALL_NR(regs) != __NR_getpid){ 231 non_fatal("check_sysemu got system call number %d, " 232 "expected %d...", PT_SYSCALL_NR(regs), __NR_getpid); 233 goto fail; 234 } 235 236 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, os_getpid()); 237 if(n < 0){ 238 non_fatal("check_sysemu : failed to modify system call " 239 "return"); 240 goto fail; 241 } 242 243 if (stop_ptraced_child(pid, stack, 0, 0) < 0) 244 goto fail_stopped; 245 246 sysemu_supported = 1; 247 non_fatal("OK\n"); 248 set_using_sysemu(!force_sysemu_disabled); 249 250 non_fatal("Checking advanced syscall emulation patch for ptrace..."); 251 pid = start_ptraced_child(&stack); 252 253 if((ptrace(PTRACE_OLDSETOPTIONS, pid, 0, 254 (void *) PTRACE_O_TRACESYSGOOD) < 0)) 255 fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed"); 256 257 while(1){ 258 count++; 259 if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0) 260 goto fail; 261 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 262 if(n < 0) 263 fatal_perror("check_ptrace : wait failed"); 264 265 if(WIFSTOPPED(status) && (WSTOPSIG(status) == (SIGTRAP|0x80))){ 266 if (!count) 267 fatal("check_ptrace : SYSEMU_SINGLESTEP " 268 "doesn't singlestep"); 269 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, 270 os_getpid()); 271 if(n < 0) 272 fatal_perror("check_sysemu : failed to modify " 273 "system call return"); 274 break; 275 } 276 else if(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP)) 277 count++; 278 else 279 fatal("check_ptrace : expected SIGTRAP or " 280 "(SIGTRAP | 0x80), got status = %d", status); 281 } 282 if (stop_ptraced_child(pid, stack, 0, 0) < 0) 283 goto fail_stopped; 284 285 sysemu_supported = 2; 286 non_fatal("OK\n"); 287 288 if ( !force_sysemu_disabled ) 289 set_using_sysemu(sysemu_supported); 290 return; 291 292 fail: 293 stop_ptraced_child(pid, stack, 1, 0); 294 fail_stopped: 295 non_fatal("missing\n"); 296 } 297 298 static void __init check_ptrace(void) 299 { 300 void *stack; 301 int pid, syscall, n, status; 302 303 non_fatal("Checking that ptrace can change system call numbers..."); 304 pid = start_ptraced_child(&stack); 305 306 if((ptrace(PTRACE_OLDSETOPTIONS, pid, 0, 307 (void *) PTRACE_O_TRACESYSGOOD) < 0)) 308 fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed"); 309 310 while(1){ 311 if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0) 312 fatal_perror("check_ptrace : ptrace failed"); 313 314 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 315 if(n < 0) 316 fatal_perror("check_ptrace : wait failed"); 317 318 if(!WIFSTOPPED(status) || 319 (WSTOPSIG(status) != (SIGTRAP | 0x80))) 320 fatal("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 fatal_perror("check_ptrace : failed to modify " 330 "system call"); 331 break; 332 } 333 } 334 stop_ptraced_child(pid, stack, 0, 1); 335 non_fatal("OK\n"); 336 check_sysemu(); 337 } 338 339 extern void check_tmpexec(void); 340 341 static void __init check_coredump_limit(void) 342 { 343 struct rlimit lim; 344 int err = getrlimit(RLIMIT_CORE, &lim); 345 346 if(err){ 347 perror("Getting core dump limit"); 348 return; 349 } 350 351 printf("Core dump limits :\n\tsoft - "); 352 if(lim.rlim_cur == RLIM_INFINITY) 353 printf("NONE\n"); 354 else printf("%lu\n", lim.rlim_cur); 355 356 printf("\thard - "); 357 if(lim.rlim_max == RLIM_INFINITY) 358 printf("NONE\n"); 359 else printf("%lu\n", lim.rlim_max); 360 } 361 362 void __init os_early_checks(void) 363 { 364 /* Print out the core dump limits early */ 365 check_coredump_limit(); 366 367 check_ptrace(); 368 369 /* Need to check this early because mmapping happens before the 370 * kernel is running. 371 */ 372 check_tmpexec(); 373 } 374 375 static int __init noprocmm_cmd_param(char *str, int* add) 376 { 377 proc_mm = 0; 378 return 0; 379 } 380 381 __uml_setup("noprocmm", noprocmm_cmd_param, 382 "noprocmm\n" 383 " Turns off usage of /proc/mm, even if host supports it.\n" 384 " To support /proc/mm, the host needs to be patched using\n" 385 " the current skas3 patch.\n\n"); 386 387 static int __init noptracefaultinfo_cmd_param(char *str, int* add) 388 { 389 ptrace_faultinfo = 0; 390 return 0; 391 } 392 393 __uml_setup("noptracefaultinfo", noptracefaultinfo_cmd_param, 394 "noptracefaultinfo\n" 395 " Turns off usage of PTRACE_FAULTINFO, even if host supports\n" 396 " it. To support PTRACE_FAULTINFO, the host needs to be patched\n" 397 " using the current skas3 patch.\n\n"); 398 399 static int __init noptraceldt_cmd_param(char *str, int* add) 400 { 401 ptrace_ldt = 0; 402 return 0; 403 } 404 405 __uml_setup("noptraceldt", noptraceldt_cmd_param, 406 "noptraceldt\n" 407 " Turns off usage of PTRACE_LDT, even if host supports it.\n" 408 " To support PTRACE_LDT, the host needs to be patched using\n" 409 " the current skas3 patch.\n\n"); 410 411 #ifdef UML_CONFIG_MODE_SKAS 412 static inline void check_skas3_ptrace_faultinfo(void) 413 { 414 struct ptrace_faultinfo fi; 415 void *stack; 416 int pid, n; 417 418 non_fatal(" - PTRACE_FAULTINFO..."); 419 pid = start_ptraced_child(&stack); 420 421 n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi); 422 if (n < 0) { 423 ptrace_faultinfo = 0; 424 if(errno == EIO) 425 non_fatal("not found\n"); 426 else 427 perror("not found"); 428 } 429 else { 430 if (!ptrace_faultinfo) 431 non_fatal("found but disabled on command line\n"); 432 else 433 non_fatal("found\n"); 434 } 435 436 init_registers(pid); 437 stop_ptraced_child(pid, stack, 1, 1); 438 } 439 440 static inline void check_skas3_ptrace_ldt(void) 441 { 442 #ifdef PTRACE_LDT 443 void *stack; 444 int pid, n; 445 unsigned char ldtbuf[40]; 446 struct ptrace_ldt ldt_op = (struct ptrace_ldt) { 447 .func = 2, /* read default ldt */ 448 .ptr = ldtbuf, 449 .bytecount = sizeof(ldtbuf)}; 450 451 non_fatal(" - PTRACE_LDT..."); 452 pid = start_ptraced_child(&stack); 453 454 n = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op); 455 if (n < 0) { 456 if(errno == EIO) 457 non_fatal("not found\n"); 458 else { 459 perror("not found"); 460 } 461 ptrace_ldt = 0; 462 } 463 else { 464 if(ptrace_ldt) 465 non_fatal("found\n"); 466 else 467 non_fatal("found, but use is disabled\n"); 468 } 469 470 stop_ptraced_child(pid, stack, 1, 1); 471 #else 472 /* PTRACE_LDT might be disabled via cmdline option. 473 * We want to override this, else we might use the stub 474 * without real need 475 */ 476 ptrace_ldt = 1; 477 #endif 478 } 479 480 static inline void check_skas3_proc_mm(void) 481 { 482 non_fatal(" - /proc/mm..."); 483 if (access("/proc/mm", W_OK) < 0) { 484 proc_mm = 0; 485 perror("not found"); 486 } 487 else { 488 if (!proc_mm) 489 non_fatal("found but disabled on command line\n"); 490 else 491 non_fatal("found\n"); 492 } 493 } 494 495 int can_do_skas(void) 496 { 497 non_fatal("Checking for the skas3 patch in the host:\n"); 498 499 check_skas3_proc_mm(); 500 check_skas3_ptrace_faultinfo(); 501 check_skas3_ptrace_ldt(); 502 503 if(!proc_mm || !ptrace_faultinfo || !ptrace_ldt) 504 skas_needs_stub = 1; 505 506 return 1; 507 } 508 #else 509 int can_do_skas(void) 510 { 511 return 0; 512 } 513 #endif 514 515 int __init parse_iomem(char *str, int *add) 516 { 517 struct iomem_region *new; 518 struct stat64 buf; 519 char *file, *driver; 520 int fd, size; 521 522 driver = str; 523 file = strchr(str,','); 524 if(file == NULL){ 525 printf("parse_iomem : failed to parse iomem\n"); 526 goto out; 527 } 528 *file = '\0'; 529 file++; 530 fd = open(file, O_RDWR, 0); 531 if(fd < 0){ 532 os_print_error(fd, "parse_iomem - Couldn't open io file"); 533 goto out; 534 } 535 536 if(fstat64(fd, &buf) < 0){ 537 perror("parse_iomem - cannot stat_fd file"); 538 goto out_close; 539 } 540 541 new = malloc(sizeof(*new)); 542 if(new == NULL){ 543 perror("Couldn't allocate iomem_region struct"); 544 goto out_close; 545 } 546 547 size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1); 548 549 *new = ((struct iomem_region) { .next = iomem_regions, 550 .driver = driver, 551 .fd = fd, 552 .size = size, 553 .phys = 0, 554 .virt = 0 }); 555 iomem_regions = new; 556 iomem_size += new->size + UM_KERN_PAGE_SIZE; 557 558 return 0; 559 out_close: 560 close(fd); 561 out: 562 return 1; 563 } 564