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