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