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 int ptrace_faultinfo = 1; 137 int ptrace_ldt = 1; 138 int proc_mm = 1; 139 int skas_needs_stub = 0; 140 141 static int __init skas0_cmd_param(char *str, int* add) 142 { 143 ptrace_faultinfo = proc_mm = 0; 144 return 0; 145 } 146 147 /* The two __uml_setup would conflict, without this stupid alias. */ 148 149 static int __init mode_skas0_cmd_param(char *str, int* add) 150 __attribute__((alias("skas0_cmd_param"))); 151 152 __uml_setup("skas0", skas0_cmd_param, 153 "skas0\n" 154 " Disables SKAS3 usage, so that SKAS0 is used, unless \n" 155 " you specify mode=tt.\n\n"); 156 157 __uml_setup("mode=skas0", mode_skas0_cmd_param, 158 "mode=skas0\n" 159 " Disables SKAS3 usage, so that SKAS0 is used, unless you \n" 160 " specify mode=tt. Note that this was recently added - on \n" 161 " older kernels you must use simply \"skas0\".\n\n"); 162 163 static int force_sysemu_disabled = 0; 164 165 static int __init nosysemu_cmd_param(char *str, int* add) 166 { 167 force_sysemu_disabled = 1; 168 return 0; 169 } 170 171 __uml_setup("nosysemu", nosysemu_cmd_param, 172 "nosysemu\n" 173 " Turns off syscall emulation patch for ptrace (SYSEMU) on.\n" 174 " SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n" 175 " behaviour of ptrace() and helps reducing host context switch rate.\n" 176 " To make it working, you need a kernel patch for your host, too.\n" 177 " See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n" 178 " information.\n\n"); 179 180 static void __init check_sysemu(void) 181 { 182 void *stack; 183 int pid, n, status, count=0; 184 185 printf("Checking syscall emulation patch for ptrace..."); 186 sysemu_supported = 0; 187 pid = start_ptraced_child(&stack); 188 189 if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0) 190 goto fail; 191 192 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 193 if (n < 0) 194 panic("check_sysemu : wait failed, errno = %d", errno); 195 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP)) 196 panic("check_sysemu : expected SIGTRAP, " 197 "got status = %d", status); 198 199 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, 200 os_getpid()); 201 if(n < 0) 202 panic("check_sysemu : failed to modify system " 203 "call return, errno = %d", errno); 204 205 if (stop_ptraced_child(pid, stack, 0, 0) < 0) 206 goto fail_stopped; 207 208 sysemu_supported = 1; 209 printf("OK\n"); 210 set_using_sysemu(!force_sysemu_disabled); 211 212 printf("Checking advanced syscall emulation patch for ptrace..."); 213 pid = start_ptraced_child(&stack); 214 215 if(ptrace(PTRACE_OLDSETOPTIONS, pid, 0, 216 (void *) PTRACE_O_TRACESYSGOOD) < 0) 217 panic("check_ptrace: PTRACE_OLDSETOPTIONS failed, errno = %d", 218 errno); 219 220 while(1){ 221 count++; 222 if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0) 223 goto fail; 224 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 225 if(n < 0) 226 panic("check_ptrace : wait failed, errno = %d", errno); 227 if(WIFSTOPPED(status) && (WSTOPSIG(status) == (SIGTRAP|0x80))){ 228 if (!count) 229 panic("check_ptrace : SYSEMU_SINGLESTEP " 230 "doesn't singlestep"); 231 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, 232 os_getpid()); 233 if(n < 0) 234 panic("check_sysemu : failed to modify system " 235 "call return, errno = %d", errno); 236 break; 237 } 238 else if(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP)) 239 count++; 240 else 241 panic("check_ptrace : expected SIGTRAP or " 242 "(SIGTRAP|0x80), got status = %d", status); 243 } 244 if (stop_ptraced_child(pid, stack, 0, 0) < 0) 245 goto fail_stopped; 246 247 sysemu_supported = 2; 248 printf("OK\n"); 249 250 if ( !force_sysemu_disabled ) 251 set_using_sysemu(sysemu_supported); 252 return; 253 254 fail: 255 stop_ptraced_child(pid, stack, 1, 0); 256 fail_stopped: 257 printf("missing\n"); 258 } 259 260 static void __init check_ptrace(void) 261 { 262 void *stack; 263 int pid, syscall, n, status; 264 265 printf("Checking that ptrace can change system call numbers..."); 266 pid = start_ptraced_child(&stack); 267 268 if(ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0) 269 panic("check_ptrace: PTRACE_OLDSETOPTIONS failed, errno = %d", errno); 270 271 while(1){ 272 if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0) 273 panic("check_ptrace : ptrace failed, errno = %d", 274 errno); 275 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); 276 if(n < 0) 277 panic("check_ptrace : wait failed, errno = %d", errno); 278 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != (SIGTRAP|0x80))) 279 panic("check_ptrace : expected (SIGTRAP|0x80), " 280 "got status = %d", status); 281 282 syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET, 283 0); 284 if(syscall == __NR_getpid){ 285 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET, 286 __NR_getppid); 287 if(n < 0) 288 panic("check_ptrace : failed to modify system " 289 "call, errno = %d", errno); 290 break; 291 } 292 } 293 stop_ptraced_child(pid, stack, 0, 1); 294 printf("OK\n"); 295 check_sysemu(); 296 } 297 298 extern void check_tmpexec(void); 299 300 void os_early_checks(void) 301 { 302 check_ptrace(); 303 304 /* Need to check this early because mmapping happens before the 305 * kernel is running. 306 */ 307 check_tmpexec(); 308 } 309 310 static int __init noprocmm_cmd_param(char *str, int* add) 311 { 312 proc_mm = 0; 313 return 0; 314 } 315 316 __uml_setup("noprocmm", noprocmm_cmd_param, 317 "noprocmm\n" 318 " Turns off usage of /proc/mm, even if host supports it.\n" 319 " To support /proc/mm, the host needs to be patched using\n" 320 " the current skas3 patch.\n\n"); 321 322 static int __init noptracefaultinfo_cmd_param(char *str, int* add) 323 { 324 ptrace_faultinfo = 0; 325 return 0; 326 } 327 328 __uml_setup("noptracefaultinfo", noptracefaultinfo_cmd_param, 329 "noptracefaultinfo\n" 330 " Turns off usage of PTRACE_FAULTINFO, even if host supports\n" 331 " it. To support PTRACE_FAULTINFO, the host needs to be patched\n" 332 " using the current skas3 patch.\n\n"); 333 334 static int __init noptraceldt_cmd_param(char *str, int* add) 335 { 336 ptrace_ldt = 0; 337 return 0; 338 } 339 340 __uml_setup("noptraceldt", noptraceldt_cmd_param, 341 "noptraceldt\n" 342 " Turns off usage of PTRACE_LDT, even if host supports it.\n" 343 " To support PTRACE_LDT, the host needs to be patched using\n" 344 " the current skas3 patch.\n\n"); 345 346 #ifdef UML_CONFIG_MODE_SKAS 347 static inline void check_skas3_ptrace_faultinfo(void) 348 { 349 struct ptrace_faultinfo fi; 350 void *stack; 351 int pid, n; 352 353 printf(" - PTRACE_FAULTINFO..."); 354 pid = start_ptraced_child(&stack); 355 356 n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi); 357 if (n < 0) { 358 ptrace_faultinfo = 0; 359 if(errno == EIO) 360 printf("not found\n"); 361 else 362 perror("not found"); 363 } 364 else { 365 if (!ptrace_faultinfo) 366 printf("found but disabled on command line\n"); 367 else 368 printf("found\n"); 369 } 370 371 init_registers(pid); 372 stop_ptraced_child(pid, stack, 1, 1); 373 } 374 375 static inline void check_skas3_ptrace_ldt(void) 376 { 377 #ifdef PTRACE_LDT 378 void *stack; 379 int pid, n; 380 unsigned char ldtbuf[40]; 381 struct ptrace_ldt ldt_op = (struct ptrace_ldt) { 382 .func = 2, /* read default ldt */ 383 .ptr = ldtbuf, 384 .bytecount = sizeof(ldtbuf)}; 385 386 printf(" - PTRACE_LDT..."); 387 pid = start_ptraced_child(&stack); 388 389 n = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op); 390 if (n < 0) { 391 if(errno == EIO) 392 printf("not found\n"); 393 else { 394 perror("not found"); 395 } 396 ptrace_ldt = 0; 397 } 398 else { 399 if(ptrace_ldt) 400 printf("found\n"); 401 else 402 printf("found, but use is disabled\n"); 403 } 404 405 stop_ptraced_child(pid, stack, 1, 1); 406 #else 407 /* PTRACE_LDT might be disabled via cmdline option. 408 * We want to override this, else we might use the stub 409 * without real need 410 */ 411 ptrace_ldt = 1; 412 #endif 413 } 414 415 static inline void check_skas3_proc_mm(void) 416 { 417 printf(" - /proc/mm..."); 418 if (os_access("/proc/mm", OS_ACC_W_OK) < 0) { 419 proc_mm = 0; 420 printf("not found\n"); 421 } 422 else { 423 if (!proc_mm) 424 printf("found but disabled on command line\n"); 425 else 426 printf("found\n"); 427 } 428 } 429 430 int can_do_skas(void) 431 { 432 printf("Checking for the skas3 patch in the host:\n"); 433 434 check_skas3_proc_mm(); 435 check_skas3_ptrace_faultinfo(); 436 check_skas3_ptrace_ldt(); 437 438 if(!proc_mm || !ptrace_faultinfo || !ptrace_ldt) 439 skas_needs_stub = 1; 440 441 return 1; 442 } 443 #else 444 int can_do_skas(void) 445 { 446 return(0); 447 } 448 #endif 449 450 int __init parse_iomem(char *str, int *add) 451 { 452 struct iomem_region *new; 453 struct uml_stat buf; 454 char *file, *driver; 455 int fd, err, size; 456 457 driver = str; 458 file = strchr(str,','); 459 if(file == NULL){ 460 printf("parse_iomem : failed to parse iomem\n"); 461 goto out; 462 } 463 *file = '\0'; 464 file++; 465 fd = os_open_file(file, of_rdwr(OPENFLAGS()), 0); 466 if(fd < 0){ 467 os_print_error(fd, "parse_iomem - Couldn't open io file"); 468 goto out; 469 } 470 471 err = os_stat_fd(fd, &buf); 472 if(err < 0){ 473 os_print_error(err, "parse_iomem - cannot stat_fd file"); 474 goto out_close; 475 } 476 477 new = malloc(sizeof(*new)); 478 if(new == NULL){ 479 perror("Couldn't allocate iomem_region struct"); 480 goto out_close; 481 } 482 483 size = (buf.ust_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1); 484 485 *new = ((struct iomem_region) { .next = iomem_regions, 486 .driver = driver, 487 .fd = fd, 488 .size = size, 489 .phys = 0, 490 .virt = 0 }); 491 iomem_regions = new; 492 iomem_size += new->size + UM_KERN_PAGE_SIZE; 493 494 return(0); 495 out_close: 496 os_close_file(fd); 497 out: 498 return(1); 499 } 500 501 502 /* Changed during early boot */ 503 int pty_output_sigio = 0; 504 int pty_close_sigio = 0; 505 506 /* Used as a flag during SIGIO testing early in boot */ 507 static volatile int got_sigio = 0; 508 509 static void __init handler(int sig) 510 { 511 got_sigio = 1; 512 } 513 514 struct openpty_arg { 515 int master; 516 int slave; 517 int err; 518 }; 519 520 static void openpty_cb(void *arg) 521 { 522 struct openpty_arg *info = arg; 523 524 info->err = 0; 525 if(openpty(&info->master, &info->slave, NULL, NULL, NULL)) 526 info->err = -errno; 527 } 528 529 static void __init check_one_sigio(void (*proc)(int, int)) 530 { 531 struct sigaction old, new; 532 struct openpty_arg pty = { .master = -1, .slave = -1 }; 533 int master, slave, err; 534 535 initial_thread_cb(openpty_cb, &pty); 536 if(pty.err){ 537 printk("openpty failed, errno = %d\n", -pty.err); 538 return; 539 } 540 541 master = pty.master; 542 slave = pty.slave; 543 544 if((master == -1) || (slave == -1)){ 545 printk("openpty failed to allocate a pty\n"); 546 return; 547 } 548 549 /* Not now, but complain so we now where we failed. */ 550 err = raw(master); 551 if (err < 0) 552 panic("check_sigio : __raw failed, errno = %d\n", -err); 553 554 err = os_sigio_async(master, slave); 555 if(err < 0) 556 panic("tty_fds : sigio_async failed, err = %d\n", -err); 557 558 if(sigaction(SIGIO, NULL, &old) < 0) 559 panic("check_sigio : sigaction 1 failed, errno = %d\n", errno); 560 new = old; 561 new.sa_handler = handler; 562 if(sigaction(SIGIO, &new, NULL) < 0) 563 panic("check_sigio : sigaction 2 failed, errno = %d\n", errno); 564 565 got_sigio = 0; 566 (*proc)(master, slave); 567 568 close(master); 569 close(slave); 570 571 if(sigaction(SIGIO, &old, NULL) < 0) 572 panic("check_sigio : sigaction 3 failed, errno = %d\n", errno); 573 } 574 575 static void tty_output(int master, int slave) 576 { 577 int n; 578 char buf[512]; 579 580 printk("Checking that host ptys support output SIGIO..."); 581 582 memset(buf, 0, sizeof(buf)); 583 584 while(os_write_file(master, buf, sizeof(buf)) > 0) ; 585 if(errno != EAGAIN) 586 panic("check_sigio : write failed, errno = %d\n", errno); 587 while(((n = os_read_file(slave, buf, sizeof(buf))) > 0) && !got_sigio) ; 588 589 if(got_sigio){ 590 printk("Yes\n"); 591 pty_output_sigio = 1; 592 } 593 else if(n == -EAGAIN) printk("No, enabling workaround\n"); 594 else panic("check_sigio : read failed, err = %d\n", n); 595 } 596 597 static void tty_close(int master, int slave) 598 { 599 printk("Checking that host ptys support SIGIO on close..."); 600 601 close(slave); 602 if(got_sigio){ 603 printk("Yes\n"); 604 pty_close_sigio = 1; 605 } 606 else printk("No, enabling workaround\n"); 607 } 608 609 void __init check_sigio(void) 610 { 611 if((os_access("/dev/ptmx", OS_ACC_R_OK) < 0) && 612 (os_access("/dev/ptyp0", OS_ACC_R_OK) < 0)){ 613 printk("No pseudo-terminals available - skipping pty SIGIO " 614 "check\n"); 615 return; 616 } 617 check_one_sigio(tty_output); 618 check_one_sigio(tty_close); 619 } 620 621 void os_check_bugs(void) 622 { 623 check_ptrace(); 624 check_sigio(); 625 } 626 627