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 <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 "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 os_stop_process(pid); 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 int start_ptraced_child(void **stack_out) 77 { 78 void *stack; 79 unsigned long sp; 80 int pid, n, status; 81 82 stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC, 83 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); 84 if(stack == MAP_FAILED) 85 panic("check_ptrace : mmap failed, errno = %d", errno); 86 sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *); 87 pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL); 88 if(pid < 0) 89 panic("start_ptraced_child : clone failed, errno = %d", errno); 90 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 91 if(n < 0) 92 panic("check_ptrace : clone failed, errno = %d", errno); 93 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) 94 panic("check_ptrace : expected SIGSTOP, got status = %d", 95 status); 96 97 *stack_out = stack; 98 return pid; 99 } 100 101 /* When testing for SYSEMU support, if it is one of the broken versions, we 102 * must just avoid using sysemu, not panic, but only if SYSEMU features are 103 * broken. 104 * So only for SYSEMU features we test mustpanic, while normal host features 105 * must work anyway! 106 */ 107 static int stop_ptraced_child(int pid, void *stack, int exitcode, 108 int mustpanic) 109 { 110 int status, n, ret = 0; 111 112 if(ptrace(PTRACE_CONT, pid, 0, 0) < 0) 113 panic("check_ptrace : ptrace failed, errno = %d", errno); 114 CATCH_EINTR(n = waitpid(pid, &status, 0)); 115 if(!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) { 116 int exit_with = WEXITSTATUS(status); 117 if (exit_with == 2) 118 printf("check_ptrace : child exited with status 2. " 119 "Serious trouble happening! Try updating your " 120 "host skas patch!\nDisabling SYSEMU support."); 121 printf("check_ptrace : child exited with exitcode %d, while " 122 "expecting %d; status 0x%x", exit_with, 123 exitcode, status); 124 if (mustpanic) 125 panic("\n"); 126 else 127 printf("\n"); 128 ret = -1; 129 } 130 131 if(munmap(stack, PAGE_SIZE) < 0) 132 panic("check_ptrace : munmap failed, errno = %d", errno); 133 return ret; 134 } 135 136 /* Changed only during early boot */ 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 /* Changed only during early boot */ 165 static int force_sysemu_disabled = 0; 166 167 static int __init nosysemu_cmd_param(char *str, int* add) 168 { 169 force_sysemu_disabled = 1; 170 return 0; 171 } 172 173 __uml_setup("nosysemu", nosysemu_cmd_param, 174 "nosysemu\n" 175 " Turns off syscall emulation patch for ptrace (SYSEMU) on.\n" 176 " SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n" 177 " behaviour of ptrace() and helps reducing host context switch rate.\n" 178 " To make it working, you need a kernel patch for your host, too.\n" 179 " See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n" 180 " information.\n\n"); 181 182 static void __init check_sysemu(void) 183 { 184 void *stack; 185 int pid, n, status, count=0; 186 187 printf("Checking syscall emulation patch for ptrace..."); 188 sysemu_supported = 0; 189 pid = start_ptraced_child(&stack); 190 191 if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0) 192 goto fail; 193 194 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 195 if (n < 0) 196 panic("check_sysemu : wait failed, errno = %d", errno); 197 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP)) 198 panic("check_sysemu : expected SIGTRAP, " 199 "got status = %d", status); 200 201 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, 202 os_getpid()); 203 if(n < 0) 204 panic("check_sysemu : failed to modify system " 205 "call return, errno = %d", errno); 206 207 if (stop_ptraced_child(pid, stack, 0, 0) < 0) 208 goto fail_stopped; 209 210 sysemu_supported = 1; 211 printf("OK\n"); 212 set_using_sysemu(!force_sysemu_disabled); 213 214 printf("Checking advanced syscall emulation patch for ptrace..."); 215 pid = start_ptraced_child(&stack); 216 217 if(ptrace(PTRACE_OLDSETOPTIONS, pid, 0, 218 (void *) PTRACE_O_TRACESYSGOOD) < 0) 219 panic("check_ptrace: PTRACE_OLDSETOPTIONS failed, errno = %d", 220 errno); 221 222 while(1){ 223 count++; 224 if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0) 225 goto fail; 226 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 227 if(n < 0) 228 panic("check_ptrace : wait failed, errno = %d", errno); 229 if(WIFSTOPPED(status) && (WSTOPSIG(status) == (SIGTRAP|0x80))){ 230 if (!count) 231 panic("check_ptrace : SYSEMU_SINGLESTEP " 232 "doesn't singlestep"); 233 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, 234 os_getpid()); 235 if(n < 0) 236 panic("check_sysemu : failed to modify system " 237 "call return, errno = %d", errno); 238 break; 239 } 240 else if(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP)) 241 count++; 242 else 243 panic("check_ptrace : expected SIGTRAP or " 244 "(SIGTRAP|0x80), got status = %d", status); 245 } 246 if (stop_ptraced_child(pid, stack, 0, 0) < 0) 247 goto fail_stopped; 248 249 sysemu_supported = 2; 250 printf("OK\n"); 251 252 if ( !force_sysemu_disabled ) 253 set_using_sysemu(sysemu_supported); 254 return; 255 256 fail: 257 stop_ptraced_child(pid, stack, 1, 0); 258 fail_stopped: 259 printf("missing\n"); 260 } 261 262 static void __init check_ptrace(void) 263 { 264 void *stack; 265 int pid, syscall, n, status; 266 267 printf("Checking that ptrace can change system call numbers..."); 268 pid = start_ptraced_child(&stack); 269 270 if(ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0) 271 panic("check_ptrace: PTRACE_OLDSETOPTIONS failed, errno = %d", errno); 272 273 while(1){ 274 if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0) 275 panic("check_ptrace : ptrace failed, errno = %d", 276 errno); 277 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 278 if(n < 0) 279 panic("check_ptrace : wait failed, errno = %d", errno); 280 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != (SIGTRAP|0x80))) 281 panic("check_ptrace : expected (SIGTRAP|0x80), " 282 "got status = %d", status); 283 284 syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET, 285 0); 286 if(syscall == __NR_getpid){ 287 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET, 288 __NR_getppid); 289 if(n < 0) 290 panic("check_ptrace : failed to modify system " 291 "call, errno = %d", errno); 292 break; 293 } 294 } 295 stop_ptraced_child(pid, stack, 0, 1); 296 printf("OK\n"); 297 check_sysemu(); 298 } 299 300 extern void check_tmpexec(void); 301 302 void os_early_checks(void) 303 { 304 check_ptrace(); 305 306 /* Need to check this early because mmapping happens before the 307 * kernel is running. 308 */ 309 check_tmpexec(); 310 } 311 312 static int __init noprocmm_cmd_param(char *str, int* add) 313 { 314 proc_mm = 0; 315 return 0; 316 } 317 318 __uml_setup("noprocmm", noprocmm_cmd_param, 319 "noprocmm\n" 320 " Turns off usage of /proc/mm, even if host supports it.\n" 321 " To support /proc/mm, the host needs to be patched using\n" 322 " the current skas3 patch.\n\n"); 323 324 static int __init noptracefaultinfo_cmd_param(char *str, int* add) 325 { 326 ptrace_faultinfo = 0; 327 return 0; 328 } 329 330 __uml_setup("noptracefaultinfo", noptracefaultinfo_cmd_param, 331 "noptracefaultinfo\n" 332 " Turns off usage of PTRACE_FAULTINFO, even if host supports\n" 333 " it. To support PTRACE_FAULTINFO, the host needs to be patched\n" 334 " using the current skas3 patch.\n\n"); 335 336 static int __init noptraceldt_cmd_param(char *str, int* add) 337 { 338 ptrace_ldt = 0; 339 return 0; 340 } 341 342 __uml_setup("noptraceldt", noptraceldt_cmd_param, 343 "noptraceldt\n" 344 " Turns off usage of PTRACE_LDT, even if host supports it.\n" 345 " To support PTRACE_LDT, the host needs to be patched using\n" 346 " the current skas3 patch.\n\n"); 347 348 #ifdef UML_CONFIG_MODE_SKAS 349 static inline void check_skas3_ptrace_faultinfo(void) 350 { 351 struct ptrace_faultinfo fi; 352 void *stack; 353 int pid, n; 354 355 printf(" - PTRACE_FAULTINFO..."); 356 pid = start_ptraced_child(&stack); 357 358 n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi); 359 if (n < 0) { 360 ptrace_faultinfo = 0; 361 if(errno == EIO) 362 printf("not found\n"); 363 else 364 perror("not found"); 365 } 366 else { 367 if (!ptrace_faultinfo) 368 printf("found but disabled on command line\n"); 369 else 370 printf("found\n"); 371 } 372 373 init_registers(pid); 374 stop_ptraced_child(pid, stack, 1, 1); 375 } 376 377 static inline void check_skas3_ptrace_ldt(void) 378 { 379 #ifdef PTRACE_LDT 380 void *stack; 381 int pid, n; 382 unsigned char ldtbuf[40]; 383 struct ptrace_ldt ldt_op = (struct ptrace_ldt) { 384 .func = 2, /* read default ldt */ 385 .ptr = ldtbuf, 386 .bytecount = sizeof(ldtbuf)}; 387 388 printf(" - PTRACE_LDT..."); 389 pid = start_ptraced_child(&stack); 390 391 n = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op); 392 if (n < 0) { 393 if(errno == EIO) 394 printf("not found\n"); 395 else { 396 perror("not found"); 397 } 398 ptrace_ldt = 0; 399 } 400 else { 401 if(ptrace_ldt) 402 printf("found\n"); 403 else 404 printf("found, but use is disabled\n"); 405 } 406 407 stop_ptraced_child(pid, stack, 1, 1); 408 #else 409 /* PTRACE_LDT might be disabled via cmdline option. 410 * We want to override this, else we might use the stub 411 * without real need 412 */ 413 ptrace_ldt = 1; 414 #endif 415 } 416 417 static inline void check_skas3_proc_mm(void) 418 { 419 printf(" - /proc/mm..."); 420 if (os_access("/proc/mm", OS_ACC_W_OK) < 0) { 421 proc_mm = 0; 422 printf("not found\n"); 423 } 424 else { 425 if (!proc_mm) 426 printf("found but disabled on command line\n"); 427 else 428 printf("found\n"); 429 } 430 } 431 432 int can_do_skas(void) 433 { 434 printf("Checking for the skas3 patch in the host:\n"); 435 436 check_skas3_proc_mm(); 437 check_skas3_ptrace_faultinfo(); 438 check_skas3_ptrace_ldt(); 439 440 if(!proc_mm || !ptrace_faultinfo || !ptrace_ldt) 441 skas_needs_stub = 1; 442 443 return 1; 444 } 445 #else 446 int can_do_skas(void) 447 { 448 return 0; 449 } 450 #endif 451 452 int __init parse_iomem(char *str, int *add) 453 { 454 struct iomem_region *new; 455 struct uml_stat buf; 456 char *file, *driver; 457 int fd, err, size; 458 459 driver = str; 460 file = strchr(str,','); 461 if(file == NULL){ 462 printf("parse_iomem : failed to parse iomem\n"); 463 goto out; 464 } 465 *file = '\0'; 466 file++; 467 fd = os_open_file(file, of_rdwr(OPENFLAGS()), 0); 468 if(fd < 0){ 469 os_print_error(fd, "parse_iomem - Couldn't open io file"); 470 goto out; 471 } 472 473 err = os_stat_fd(fd, &buf); 474 if(err < 0){ 475 os_print_error(err, "parse_iomem - cannot stat_fd file"); 476 goto out_close; 477 } 478 479 new = malloc(sizeof(*new)); 480 if(new == NULL){ 481 perror("Couldn't allocate iomem_region struct"); 482 goto out_close; 483 } 484 485 size = (buf.ust_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1); 486 487 *new = ((struct iomem_region) { .next = iomem_regions, 488 .driver = driver, 489 .fd = fd, 490 .size = size, 491 .phys = 0, 492 .virt = 0 }); 493 iomem_regions = new; 494 iomem_size += new->size + UM_KERN_PAGE_SIZE; 495 496 return 0; 497 out_close: 498 os_close_file(fd); 499 out: 500 return 1; 501 } 502 503 504 /* Changed during early boot */ 505 int pty_output_sigio = 0; 506 int pty_close_sigio = 0; 507 508 /* Used as a flag during SIGIO testing early in boot */ 509 static volatile int got_sigio = 0; 510 511 static void __init handler(int sig) 512 { 513 got_sigio = 1; 514 } 515 516 struct openpty_arg { 517 int master; 518 int slave; 519 int err; 520 }; 521 522 static void openpty_cb(void *arg) 523 { 524 struct openpty_arg *info = arg; 525 526 info->err = 0; 527 if(openpty(&info->master, &info->slave, NULL, NULL, NULL)) 528 info->err = -errno; 529 } 530 531 static void __init check_one_sigio(void (*proc)(int, int)) 532 { 533 struct sigaction old, new; 534 struct openpty_arg pty = { .master = -1, .slave = -1 }; 535 int master, slave, err; 536 537 initial_thread_cb(openpty_cb, &pty); 538 if(pty.err){ 539 printk("openpty failed, errno = %d\n", -pty.err); 540 return; 541 } 542 543 master = pty.master; 544 slave = pty.slave; 545 546 if((master == -1) || (slave == -1)){ 547 printk("openpty failed to allocate a pty\n"); 548 return; 549 } 550 551 /* Not now, but complain so we now where we failed. */ 552 err = raw(master); 553 if (err < 0) 554 panic("check_sigio : __raw failed, errno = %d\n", -err); 555 556 err = os_sigio_async(master, slave); 557 if(err < 0) 558 panic("tty_fds : sigio_async failed, err = %d\n", -err); 559 560 if(sigaction(SIGIO, NULL, &old) < 0) 561 panic("check_sigio : sigaction 1 failed, errno = %d\n", errno); 562 new = old; 563 new.sa_handler = handler; 564 if(sigaction(SIGIO, &new, NULL) < 0) 565 panic("check_sigio : sigaction 2 failed, errno = %d\n", errno); 566 567 got_sigio = 0; 568 (*proc)(master, slave); 569 570 close(master); 571 close(slave); 572 573 if(sigaction(SIGIO, &old, NULL) < 0) 574 panic("check_sigio : sigaction 3 failed, errno = %d\n", errno); 575 } 576 577 static void tty_output(int master, int slave) 578 { 579 int n; 580 char buf[512]; 581 582 printk("Checking that host ptys support output SIGIO..."); 583 584 memset(buf, 0, sizeof(buf)); 585 586 while(os_write_file(master, buf, sizeof(buf)) > 0) ; 587 if(errno != EAGAIN) 588 panic("check_sigio : write failed, errno = %d\n", errno); 589 while(((n = os_read_file(slave, buf, sizeof(buf))) > 0) && !got_sigio) ; 590 591 if(got_sigio){ 592 printk("Yes\n"); 593 pty_output_sigio = 1; 594 } 595 else if(n == -EAGAIN) printk("No, enabling workaround\n"); 596 else panic("check_sigio : read failed, err = %d\n", n); 597 } 598 599 static void tty_close(int master, int slave) 600 { 601 printk("Checking that host ptys support SIGIO on close..."); 602 603 close(slave); 604 if(got_sigio){ 605 printk("Yes\n"); 606 pty_close_sigio = 1; 607 } 608 else printk("No, enabling workaround\n"); 609 } 610 611 void __init check_sigio(void) 612 { 613 if((os_access("/dev/ptmx", OS_ACC_R_OK) < 0) && 614 (os_access("/dev/ptyp0", OS_ACC_R_OK) < 0)){ 615 printk("No pseudo-terminals available - skipping pty SIGIO " 616 "check\n"); 617 return; 618 } 619 check_one_sigio(tty_output); 620 check_one_sigio(tty_close); 621 } 622 623 void os_check_bugs(void) 624 { 625 check_ptrace(); 626 check_sigio(); 627 } 628 629