arch/um/os-Linux/start_up.c

   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 <setjmp.h>
  18 #include <sys/time.h>
  19 #include <sys/wait.h>
  20 #include <sys/mman.h>
  21 #include <asm/unistd.h>
  22 #include <asm/page.h>
  23 #include <sys/types.h>
  24 #include "user_util.h"
  25 #include "kern_util.h"
  26 #include "user.h"
  27 #include "signal_kern.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 "init.h"
  34 #include "os.h"
  35 #include "uml-config.h"
  36 #include "choose-mode.h"
  37 #include "mode.h"
  38 #include "tempfile.h"
  39 #include "kern_constants.h"
  40
  41 #ifdef UML_CONFIG_MODE_SKAS
  42 #include "skas.h"
  43 #include "skas_ptrace.h"
  44 #include "registers.h"
  45 #endif
  46
  47 static int ptrace_child(void *arg)
  48 {
  49         int ret;
  50         int pid = os_getpid(), ppid = getppid();
  51         int sc_result;
  52
  53         change_sig(SIGWINCH, 0);
  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                         printf("check_ptrace : child exited with status 2. "
 120                                "Serious trouble happening! Try updating your "
 121                                "host skas patch!\nDisabling SYSEMU support.");
 122                 printf("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                         printf("\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         printf("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         printf("OK\n");
 211         set_using_sysemu(!force_sysemu_disabled);
 212
 213         printf("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         printf("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         printf("missing\n");
 259 }
 260
 261 static void __init check_ptrace(void)
 262 {
 263         void *stack;
 264         int pid, syscall, n, status;
 265
 266         printf("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         printf("OK\n");
 296         check_sysemu();
 297 }
 298
 299 extern void check_tmpexec(void);
 300
 301 void os_early_checks(void)
 302 {
 303         check_ptrace();
 304
 305         /* Need to check this early because mmapping happens before the
 306          * kernel is running.
 307          */
 308         check_tmpexec();
 309 }
 310
 311 static int __init noprocmm_cmd_param(char *str, int* add)
 312 {
 313         proc_mm = 0;
 314         return 0;
 315 }
 316
 317 __uml_setup("noprocmm", noprocmm_cmd_param,
 318 "noprocmm\n"
 319 "    Turns off usage of /proc/mm, even if host supports it.\n"
 320 "    To support /proc/mm, the host needs to be patched using\n"
 321 "    the current skas3 patch.\n\n");
 322
 323 static int __init noptracefaultinfo_cmd_param(char *str, int* add)
 324 {
 325         ptrace_faultinfo = 0;
 326         return 0;
 327 }
 328
 329 __uml_setup("noptracefaultinfo", noptracefaultinfo_cmd_param,
 330 "noptracefaultinfo\n"
 331 "    Turns off usage of PTRACE_FAULTINFO, even if host supports\n"
 332 "    it. To support PTRACE_FAULTINFO, the host needs to be patched\n"
 333 "    using the current skas3 patch.\n\n");
 334
 335 static int __init noptraceldt_cmd_param(char *str, int* add)
 336 {
 337         ptrace_ldt = 0;
 338         return 0;
 339 }
 340
 341 __uml_setup("noptraceldt", noptraceldt_cmd_param,
 342 "noptraceldt\n"
 343 "    Turns off usage of PTRACE_LDT, even if host supports it.\n"
 344 "    To support PTRACE_LDT, the host needs to be patched using\n"
 345 "    the current skas3 patch.\n\n");
 346
 347 #ifdef UML_CONFIG_MODE_SKAS
 348 static inline void check_skas3_ptrace_faultinfo(void)
 349 {
 350         struct ptrace_faultinfo fi;
 351         void *stack;
 352         int pid, n;
 353
 354         printf("  - PTRACE_FAULTINFO...");
 355         pid = start_ptraced_child(&stack);
 356
 357         n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
 358         if (n < 0) {
 359                 ptrace_faultinfo = 0;
 360                 if(errno == EIO)
 361                         printf("not found\n");
 362                 else
 363                         perror("not found");
 364         }
 365         else {
 366                 if (!ptrace_faultinfo)
 367                         printf("found but disabled on command line\n");
 368                 else
 369                         printf("found\n");
 370         }
 371
 372         init_registers(pid);
 373         stop_ptraced_child(pid, stack, 1, 1);
 374 }
 375
 376 static inline void check_skas3_ptrace_ldt(void)
 377 {
 378 #ifdef PTRACE_LDT
 379         void *stack;
 380         int pid, n;
 381         unsigned char ldtbuf[40];
 382         struct ptrace_ldt ldt_op = (struct ptrace_ldt) {
 383                 .func = 2, /* read default ldt */
 384                 .ptr = ldtbuf,
 385                 .bytecount = sizeof(ldtbuf)};
 386
 387         printf("  - PTRACE_LDT...");
 388         pid = start_ptraced_child(&stack);
 389
 390         n = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op);
 391         if (n < 0) {
 392                 if(errno == EIO)
 393                         printf("not found\n");
 394                 else {
 395                         perror("not found");
 396                 }
 397                 ptrace_ldt = 0;
 398         }
 399         else {
 400                 if(ptrace_ldt)
 401                         printf("found\n");
 402                 else
 403                         printf("found, but use is disabled\n");
 404         }
 405
 406         stop_ptraced_child(pid, stack, 1, 1);
 407 #else
 408         /* PTRACE_LDT might be disabled via cmdline option.
 409          * We want to override this, else we might use the stub
 410          * without real need
 411          */
 412         ptrace_ldt = 1;
 413 #endif
 414 }
 415
 416 static inline void check_skas3_proc_mm(void)
 417 {
 418         printf("  - /proc/mm...");
 419         if (os_access("/proc/mm", OS_ACC_W_OK) < 0) {
 420                 proc_mm = 0;
 421                 printf("not found\n");
 422         }
 423         else {
 424                 if (!proc_mm)
 425                         printf("found but disabled on command line\n");
 426                 else
 427                         printf("found\n");
 428         }
 429 }
 430
 431 int can_do_skas(void)
 432 {
 433         printf("Checking for the skas3 patch in the host:\n");
 434
 435         check_skas3_proc_mm();
 436         check_skas3_ptrace_faultinfo();
 437         check_skas3_ptrace_ldt();
 438
 439         if(!proc_mm || !ptrace_faultinfo || !ptrace_ldt)
 440                 skas_needs_stub = 1;
 441
 442         return 1;
 443 }
 444 #else
 445 int can_do_skas(void)
 446 {
 447         return(0);
 448 }
 449 #endif
 450
 451 int __init parse_iomem(char *str, int *add)
 452 {
 453         struct iomem_region *new;
 454         struct uml_stat buf;
 455         char *file, *driver;
 456         int fd, err, size;
 457
 458         driver = str;
 459         file = strchr(str,',');
 460         if(file == NULL){
 461                 printf("parse_iomem : failed to parse iomem\n");
 462                 goto out;
 463         }
 464         *file = '\0';
 465         file++;
 466         fd = os_open_file(file, of_rdwr(OPENFLAGS()), 0);
 467         if(fd < 0){
 468                 os_print_error(fd, "parse_iomem - Couldn't open io file");
 469                 goto out;
 470         }
 471
 472         err = os_stat_fd(fd, &buf);
 473         if(err < 0){
 474                 os_print_error(err, "parse_iomem - cannot stat_fd file");
 475                 goto out_close;
 476         }
 477
 478         new = malloc(sizeof(*new));
 479         if(new == NULL){
 480                 perror("Couldn't allocate iomem_region struct");
 481                 goto out_close;
 482         }
 483
 484         size = (buf.ust_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1);
 485
 486         *new = ((struct iomem_region) { .next           = iomem_regions,
 487                                         .driver         = driver,
 488                                         .fd             = fd,
 489                                         .size           = size,
 490                                         .phys           = 0,
 491                                         .virt           = 0 });
 492         iomem_regions = new;
 493         iomem_size += new->size + UM_KERN_PAGE_SIZE;
 494
 495         return(0);
 496  out_close:
 497         os_close_file(fd);
 498  out:
 499         return(1);
 500 }
 501
 502
 503 /* Changed during early boot */
 504 int pty_output_sigio = 0;
 505 int pty_close_sigio = 0;
 506
 507 /* Used as a flag during SIGIO testing early in boot */
 508 static volatile int got_sigio = 0;
 509
 510 static void __init handler(int sig)
 511 {
 512         got_sigio = 1;
 513 }
 514
 515 struct openpty_arg {
 516         int master;
 517         int slave;
 518         int err;
 519 };
 520
 521 static void openpty_cb(void *arg)
 522 {
 523         struct openpty_arg *info = arg;
 524
 525         info->err = 0;
 526         if(openpty(&info->master, &info->slave, NULL, NULL, NULL))
 527                 info->err = -errno;
 528 }
 529
 530 static void __init check_one_sigio(void (*proc)(int, int))
 531 {
 532         struct sigaction old, new;
 533         struct openpty_arg pty = { .master = -1, .slave = -1 };
 534         int master, slave, err;
 535
 536         initial_thread_cb(openpty_cb, &pty);
 537         if(pty.err){
 538                 printk("openpty failed, errno = %d\n", -pty.err);
 539                 return;
 540         }
 541
 542         master = pty.master;
 543         slave = pty.slave;
 544
 545         if((master == -1) || (slave == -1)){
 546                 printk("openpty failed to allocate a pty\n");
 547                 return;
 548         }
 549
 550         /* Not now, but complain so we now where we failed. */
 551         err = raw(master);
 552         if (err < 0)
 553                 panic("check_sigio : __raw failed, errno = %d\n", -err);
 554
 555         err = os_sigio_async(master, slave);
 556         if(err < 0)
 557                 panic("tty_fds : sigio_async failed, err = %d\n", -err);
 558
 559         if(sigaction(SIGIO, NULL, &old) < 0)
 560                 panic("check_sigio : sigaction 1 failed, errno = %d\n", errno);
 561         new = old;
 562         new.sa_handler = handler;
 563         if(sigaction(SIGIO, &new, NULL) < 0)
 564                 panic("check_sigio : sigaction 2 failed, errno = %d\n", errno);
 565
 566         got_sigio = 0;
 567         (*proc)(master, slave);
 568
 569         close(master);
 570         close(slave);
 571
 572         if(sigaction(SIGIO, &old, NULL) < 0)
 573                 panic("check_sigio : sigaction 3 failed, errno = %d\n", errno);
 574 }
 575
 576 static void tty_output(int master, int slave)
 577 {
 578         int n;
 579         char buf[512];
 580
 581         printk("Checking that host ptys support output SIGIO...");
 582
 583         memset(buf, 0, sizeof(buf));
 584
 585         while(os_write_file(master, buf, sizeof(buf)) > 0) ;
 586         if(errno != EAGAIN)
 587                 panic("check_sigio : write failed, errno = %d\n", errno);
 588         while(((n = os_read_file(slave, buf, sizeof(buf))) > 0) && !got_sigio) ;
 589
 590         if(got_sigio){
 591                 printk("Yes\n");
 592                 pty_output_sigio = 1;
 593         }
 594         else if(n == -EAGAIN) printk("No, enabling workaround\n");
 595         else panic("check_sigio : read failed, err = %d\n", n);
 596 }
 597
 598 static void tty_close(int master, int slave)
 599 {
 600         printk("Checking that host ptys support SIGIO on close...");
 601
 602         close(slave);
 603         if(got_sigio){
 604                 printk("Yes\n");
 605                 pty_close_sigio = 1;
 606         }
 607         else printk("No, enabling workaround\n");
 608 }
 609
 610 void __init check_sigio(void)
 611 {
 612         if((os_access("/dev/ptmx", OS_ACC_R_OK) < 0) &&
 613            (os_access("/dev/ptyp0", OS_ACC_R_OK) < 0)){
 614                 printk("No pseudo-terminals available - skipping pty SIGIO "
 615                        "check\n");
 616                 return;
 617         }
 618         check_one_sigio(tty_output);
 619         check_one_sigio(tty_close);
 620 }
 621
 622 void os_check_bugs(void)
 623 {
 624         check_ptrace();
 625         check_sigio();
 626 }
 627