1 /* 2 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) 3 * Licensed under the GPL 4 */ 5 6 #include <stdio.h> 7 #include <stdlib.h> 8 #include <stdarg.h> 9 #include <unistd.h> 10 #include <errno.h> 11 #include <fcntl.h> 12 #include <sched.h> 13 #include <signal.h> 14 #include <string.h> 15 #include <sys/mman.h> 16 #include <sys/ptrace.h> 17 #include <sys/stat.h> 18 #include <sys/wait.h> 19 #include <asm/unistd.h> 20 #include "init.h" 21 #include "kern_constants.h" 22 #include "os.h" 23 #include "mem_user.h" 24 #include "ptrace_user.h" 25 #include "registers.h" 26 #include "skas_ptrace.h" 27 28 static int ptrace_child(void) 29 { 30 int ret; 31 /* Calling os_getpid because some libcs cached getpid incorrectly */ 32 int pid = os_getpid(), ppid = getppid(); 33 int sc_result; 34 35 change_sig(SIGWINCH, 0); 36 if (ptrace(PTRACE_TRACEME, 0, 0, 0) < 0) { 37 perror("ptrace"); 38 kill(pid, SIGKILL); 39 } 40 kill(pid, SIGSTOP); 41 42 /* 43 * This syscall will be intercepted by the parent. Don't call more than 44 * once, please. 45 */ 46 sc_result = os_getpid(); 47 48 if (sc_result == pid) 49 /* Nothing modified by the parent, we are running normally. */ 50 ret = 1; 51 else if (sc_result == ppid) 52 /* 53 * Expected in check_ptrace and check_sysemu when they succeed 54 * in modifying the stack frame 55 */ 56 ret = 0; 57 else 58 /* Serious trouble! This could be caused by a bug in host 2.6 59 * SKAS3/2.6 patch before release -V6, together with a bug in 60 * the UML code itself. 61 */ 62 ret = 2; 63 _exit(ret); 64 } 65 66 static void fatal_perror(const char *str) 67 { 68 perror(str); 69 exit(1); 70 } 71 72 static void fatal(char *fmt, ...) 73 { 74 va_list list; 75 76 va_start(list, fmt); 77 vprintf(fmt, list); 78 va_end(list); 79 fflush(stdout); 80 81 exit(1); 82 } 83 84 static void non_fatal(char *fmt, ...) 85 { 86 va_list list; 87 88 va_start(list, fmt); 89 vprintf(fmt, list); 90 va_end(list); 91 fflush(stdout); 92 } 93 94 static int start_ptraced_child(void) 95 { 96 int pid, n, status; 97 98 pid = fork(); 99 if (pid == 0) 100 ptrace_child(); 101 else if (pid < 0) 102 fatal_perror("start_ptraced_child : fork failed"); 103 104 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 105 if (n < 0) 106 fatal_perror("check_ptrace : waitpid failed"); 107 if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) 108 fatal("check_ptrace : expected SIGSTOP, got status = %d", 109 status); 110 111 return pid; 112 } 113 114 /* When testing for SYSEMU support, if it is one of the broken versions, we 115 * must just avoid using sysemu, not panic, but only if SYSEMU features are 116 * broken. 117 * So only for SYSEMU features we test mustpanic, while normal host features 118 * must work anyway! 119 */ 120 static int stop_ptraced_child(int pid, int exitcode, int mustexit) 121 { 122 int status, n, ret = 0; 123 124 if (ptrace(PTRACE_CONT, pid, 0, 0) < 0) 125 fatal_perror("stop_ptraced_child : ptrace failed"); 126 CATCH_EINTR(n = waitpid(pid, &status, 0)); 127 if (!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) { 128 int exit_with = WEXITSTATUS(status); 129 if (exit_with == 2) 130 non_fatal("check_ptrace : child exited with status 2. " 131 "\nDisabling SYSEMU support.\n"); 132 non_fatal("check_ptrace : child exited with exitcode %d, while " 133 "expecting %d; status 0x%x\n", exit_with, 134 exitcode, status); 135 if (mustexit) 136 exit(1); 137 ret = -1; 138 } 139 140 return ret; 141 } 142 143 /* Changed only during early boot */ 144 int ptrace_faultinfo = 1; 145 int ptrace_ldt = 1; 146 int proc_mm = 1; 147 int skas_needs_stub = 0; 148 149 static int __init skas0_cmd_param(char *str, int* add) 150 { 151 ptrace_faultinfo = proc_mm = 0; 152 return 0; 153 } 154 155 /* The two __uml_setup would conflict, without this stupid alias. */ 156 157 static int __init mode_skas0_cmd_param(char *str, int* add) 158 __attribute__((alias("skas0_cmd_param"))); 159 160 __uml_setup("skas0", skas0_cmd_param, 161 "skas0\n" 162 " Disables SKAS3 usage, so that SKAS0 is used, unless \n" 163 " you specify mode=tt.\n\n"); 164 165 __uml_setup("mode=skas0", mode_skas0_cmd_param, 166 "mode=skas0\n" 167 " Disables SKAS3 usage, so that SKAS0 is used, unless you \n" 168 " specify mode=tt. Note that this was recently added - on \n" 169 " older kernels you must use simply \"skas0\".\n\n"); 170 171 /* Changed only during early boot */ 172 static int force_sysemu_disabled = 0; 173 174 static int __init nosysemu_cmd_param(char *str, int* add) 175 { 176 force_sysemu_disabled = 1; 177 return 0; 178 } 179 180 __uml_setup("nosysemu", nosysemu_cmd_param, 181 "nosysemu\n" 182 " Turns off syscall emulation patch for ptrace (SYSEMU) on.\n" 183 " SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n" 184 " behaviour of ptrace() and helps reducing host context switch rate.\n" 185 " To make it working, you need a kernel patch for your host, too.\n" 186 " See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n" 187 " information.\n\n"); 188 189 static void __init check_sysemu(void) 190 { 191 unsigned long regs[MAX_REG_NR]; 192 int pid, n, status, count=0; 193 194 non_fatal("Checking syscall emulation patch for ptrace..."); 195 sysemu_supported = 0; 196 pid = start_ptraced_child(); 197 198 if (ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0) 199 goto fail; 200 201 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 202 if (n < 0) 203 fatal_perror("check_sysemu : wait failed"); 204 if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP)) 205 fatal("check_sysemu : expected SIGTRAP, got status = %d", 206 status); 207 208 if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0) 209 fatal_perror("check_sysemu : PTRACE_GETREGS failed"); 210 if (PT_SYSCALL_NR(regs) != __NR_getpid) { 211 non_fatal("check_sysemu got system call number %d, " 212 "expected %d...", PT_SYSCALL_NR(regs), __NR_getpid); 213 goto fail; 214 } 215 216 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, os_getpid()); 217 if (n < 0) { 218 non_fatal("check_sysemu : failed to modify system call " 219 "return"); 220 goto fail; 221 } 222 223 if (stop_ptraced_child(pid, 0, 0) < 0) 224 goto fail_stopped; 225 226 sysemu_supported = 1; 227 non_fatal("OK\n"); 228 set_using_sysemu(!force_sysemu_disabled); 229 230 non_fatal("Checking advanced syscall emulation patch for ptrace..."); 231 pid = start_ptraced_child(); 232 233 if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0, 234 (void *) PTRACE_O_TRACESYSGOOD) < 0)) 235 fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed"); 236 237 while (1) { 238 count++; 239 if (ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0) 240 goto fail; 241 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 242 if (n < 0) 243 fatal_perror("check_ptrace : wait failed"); 244 245 if (WIFSTOPPED(status) && 246 (WSTOPSIG(status) == (SIGTRAP|0x80))) { 247 if (!count) 248 fatal("check_ptrace : SYSEMU_SINGLESTEP " 249 "doesn't singlestep"); 250 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, 251 os_getpid()); 252 if (n < 0) 253 fatal_perror("check_sysemu : failed to modify " 254 "system call return"); 255 break; 256 } 257 else if (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP)) 258 count++; 259 else 260 fatal("check_ptrace : expected SIGTRAP or " 261 "(SIGTRAP | 0x80), got status = %d", status); 262 } 263 if (stop_ptraced_child(pid, 0, 0) < 0) 264 goto fail_stopped; 265 266 sysemu_supported = 2; 267 non_fatal("OK\n"); 268 269 if (!force_sysemu_disabled) 270 set_using_sysemu(sysemu_supported); 271 return; 272 273 fail: 274 stop_ptraced_child(pid, 1, 0); 275 fail_stopped: 276 non_fatal("missing\n"); 277 } 278 279 static void __init check_ptrace(void) 280 { 281 int pid, syscall, n, status; 282 283 non_fatal("Checking that ptrace can change system call numbers..."); 284 pid = start_ptraced_child(); 285 286 if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0, 287 (void *) PTRACE_O_TRACESYSGOOD) < 0)) 288 fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed"); 289 290 while (1) { 291 if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0) 292 fatal_perror("check_ptrace : ptrace failed"); 293 294 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 295 if (n < 0) 296 fatal_perror("check_ptrace : wait failed"); 297 298 if (!WIFSTOPPED(status) || 299 (WSTOPSIG(status) != (SIGTRAP | 0x80))) 300 fatal("check_ptrace : expected (SIGTRAP|0x80), " 301 "got status = %d", status); 302 303 syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET, 304 0); 305 if (syscall == __NR_getpid) { 306 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET, 307 __NR_getppid); 308 if (n < 0) 309 fatal_perror("check_ptrace : failed to modify " 310 "system call"); 311 break; 312 } 313 } 314 stop_ptraced_child(pid, 0, 1); 315 non_fatal("OK\n"); 316 check_sysemu(); 317 } 318 319 extern void check_tmpexec(void); 320 321 static void __init check_coredump_limit(void) 322 { 323 struct rlimit lim; 324 int err = getrlimit(RLIMIT_CORE, &lim); 325 326 if (err) { 327 perror("Getting core dump limit"); 328 return; 329 } 330 331 printf("Core dump limits :\n\tsoft - "); 332 if (lim.rlim_cur == RLIM_INFINITY) 333 printf("NONE\n"); 334 else printf("%lu\n", lim.rlim_cur); 335 336 printf("\thard - "); 337 if (lim.rlim_max == RLIM_INFINITY) 338 printf("NONE\n"); 339 else printf("%lu\n", lim.rlim_max); 340 } 341 342 void __init os_early_checks(void) 343 { 344 /* Print out the core dump limits early */ 345 check_coredump_limit(); 346 347 check_ptrace(); 348 349 /* Need to check this early because mmapping happens before the 350 * kernel is running. 351 */ 352 check_tmpexec(); 353 } 354 355 static int __init noprocmm_cmd_param(char *str, int* add) 356 { 357 proc_mm = 0; 358 return 0; 359 } 360 361 __uml_setup("noprocmm", noprocmm_cmd_param, 362 "noprocmm\n" 363 " Turns off usage of /proc/mm, even if host supports it.\n" 364 " To support /proc/mm, the host needs to be patched using\n" 365 " the current skas3 patch.\n\n"); 366 367 static int __init noptracefaultinfo_cmd_param(char *str, int* add) 368 { 369 ptrace_faultinfo = 0; 370 return 0; 371 } 372 373 __uml_setup("noptracefaultinfo", noptracefaultinfo_cmd_param, 374 "noptracefaultinfo\n" 375 " Turns off usage of PTRACE_FAULTINFO, even if host supports\n" 376 " it. To support PTRACE_FAULTINFO, the host needs to be patched\n" 377 " using the current skas3 patch.\n\n"); 378 379 static int __init noptraceldt_cmd_param(char *str, int* add) 380 { 381 ptrace_ldt = 0; 382 return 0; 383 } 384 385 __uml_setup("noptraceldt", noptraceldt_cmd_param, 386 "noptraceldt\n" 387 " Turns off usage of PTRACE_LDT, even if host supports it.\n" 388 " To support PTRACE_LDT, the host needs to be patched using\n" 389 " the current skas3 patch.\n\n"); 390 391 static inline void check_skas3_ptrace_faultinfo(void) 392 { 393 struct ptrace_faultinfo fi; 394 int pid, n; 395 396 non_fatal(" - PTRACE_FAULTINFO..."); 397 pid = start_ptraced_child(); 398 399 n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi); 400 if (n < 0) { 401 ptrace_faultinfo = 0; 402 if (errno == EIO) 403 non_fatal("not found\n"); 404 else 405 perror("not found"); 406 } 407 else { 408 if (!ptrace_faultinfo) 409 non_fatal("found but disabled on command line\n"); 410 else 411 non_fatal("found\n"); 412 } 413 414 init_registers(pid); 415 stop_ptraced_child(pid, 1, 1); 416 } 417 418 static inline void check_skas3_ptrace_ldt(void) 419 { 420 #ifdef PTRACE_LDT 421 int pid, n; 422 unsigned char ldtbuf[40]; 423 struct ptrace_ldt ldt_op = (struct ptrace_ldt) { 424 .func = 2, /* read default ldt */ 425 .ptr = ldtbuf, 426 .bytecount = sizeof(ldtbuf)}; 427 428 non_fatal(" - PTRACE_LDT..."); 429 pid = start_ptraced_child(); 430 431 n = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op); 432 if (n < 0) { 433 if (errno == EIO) 434 non_fatal("not found\n"); 435 else { 436 perror("not found"); 437 } 438 ptrace_ldt = 0; 439 } 440 else { 441 if (ptrace_ldt) 442 non_fatal("found\n"); 443 else 444 non_fatal("found, but use is disabled\n"); 445 } 446 447 stop_ptraced_child(pid, 1, 1); 448 #else 449 /* PTRACE_LDT might be disabled via cmdline option. 450 * We want to override this, else we might use the stub 451 * without real need 452 */ 453 ptrace_ldt = 1; 454 #endif 455 } 456 457 static inline void check_skas3_proc_mm(void) 458 { 459 non_fatal(" - /proc/mm..."); 460 if (access("/proc/mm", W_OK) < 0) { 461 proc_mm = 0; 462 perror("not found"); 463 } 464 else if (!proc_mm) 465 non_fatal("found but disabled on command line\n"); 466 else non_fatal("found\n"); 467 } 468 469 int can_do_skas(void) 470 { 471 non_fatal("Checking for the skas3 patch in the host:\n"); 472 473 check_skas3_proc_mm(); 474 check_skas3_ptrace_faultinfo(); 475 check_skas3_ptrace_ldt(); 476 477 if (!proc_mm || !ptrace_faultinfo || !ptrace_ldt) 478 skas_needs_stub = 1; 479 480 return 1; 481 } 482 483 int __init parse_iomem(char *str, int *add) 484 { 485 struct iomem_region *new; 486 struct stat64 buf; 487 char *file, *driver; 488 int fd, size; 489 490 driver = str; 491 file = strchr(str,','); 492 if (file == NULL) { 493 printf("parse_iomem : failed to parse iomem\n"); 494 goto out; 495 } 496 *file = '\0'; 497 file++; 498 fd = open(file, O_RDWR, 0); 499 if (fd < 0) { 500 perror("parse_iomem - Couldn't open io file"); 501 goto out; 502 } 503 504 if (fstat64(fd, &buf) < 0) { 505 perror("parse_iomem - cannot stat_fd file"); 506 goto out_close; 507 } 508 509 new = malloc(sizeof(*new)); 510 if (new == NULL) { 511 perror("Couldn't allocate iomem_region struct"); 512 goto out_close; 513 } 514 515 size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1); 516 517 *new = ((struct iomem_region) { .next = iomem_regions, 518 .driver = driver, 519 .fd = fd, 520 .size = size, 521 .phys = 0, 522 .virt = 0 }); 523 iomem_regions = new; 524 iomem_size += new->size + UM_KERN_PAGE_SIZE; 525 526 return 0; 527 out_close: 528 close(fd); 529 out: 530 return 1; 531 } 532