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 <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
  39 #ifdef UML_CONFIG_MODE_SKAS
  40 #include "skas.h"
  41 #include "skas_ptrace.h"
  42 #include "registers.h"
  43 #endif
  44
  45 static int ptrace_child(void *arg)
  46 {
  47         int ret;
  48         int pid = os_getpid(), ppid = getppid();
  49         int sc_result;
  50
  51         change_sig(SIGWINCH, 0);
  52         if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0){
  53                 perror("ptrace");
  54                 os_kill_process(pid, 0);
  55         }
  56         kill(pid, SIGSTOP);
  57
  58         /*This syscall will be intercepted by the parent. Don't call more than
  59          * once, please.*/
  60         sc_result = os_getpid();
  61
  62         if (sc_result == pid)
  63                 ret = 1; /*Nothing modified by the parent, we are running
  64                            normally.*/
  65         else if (sc_result == ppid)
  66                 ret = 0; /*Expected in check_ptrace and check_sysemu when they
  67                            succeed in modifying the stack frame*/
  68         else
  69                 ret = 2; /*Serious trouble! This could be caused by a bug in
  70                            host 2.6 SKAS3/2.6 patch before release -V6, together
  71                            with a bug in the UML code itself.*/
  72         _exit(ret);
  73 }
  74
  75 static void fatal_perror(char *str)
  76 {
  77         perror(str);
  78         exit(1);
  79 }
  80
  81 static void fatal(char *fmt, ...)
  82 {
  83         va_list list;
  84
  85         va_start(list, fmt);
  86         vprintf(fmt, list);
  87         va_end(list);
  88         fflush(stdout);
  89
  90         exit(1);
  91 }
  92
  93 static void non_fatal(char *fmt, ...)
  94 {
  95         va_list list;
  96
  97         va_start(list, fmt);
  98         vprintf(fmt, list);
  99         va_end(list);
 100         fflush(stdout);
 101 }
 102
 103 static int start_ptraced_child(void **stack_out)
 104 {
 105         void *stack;
 106         unsigned long sp;
 107         int pid, n, status;
 108
 109         stack = mmap(NULL, UM_KERN_PAGE_SIZE,
 110                      PROT_READ | PROT_WRITE | PROT_EXEC,
 111                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 112         if(stack == MAP_FAILED)
 113                 fatal_perror("check_ptrace : mmap failed");
 114         sp = (unsigned long) stack + UM_KERN_PAGE_SIZE - sizeof(void *);
 115         pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL);
 116         if(pid < 0)
 117                 fatal_perror("start_ptraced_child : clone failed");
 118         CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
 119         if(n < 0)
 120                 fatal_perror("check_ptrace : clone failed");
 121         if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
 122                 fatal("check_ptrace : expected SIGSTOP, got status = %d",
 123                       status);
 124
 125         *stack_out = stack;
 126         return pid;
 127 }
 128
 129 /* When testing for SYSEMU support, if it is one of the broken versions, we
 130  * must just avoid using sysemu, not panic, but only if SYSEMU features are
 131  * broken.
 132  * So only for SYSEMU features we test mustpanic, while normal host features
 133  * must work anyway!
 134  */
 135 static int stop_ptraced_child(int pid, void *stack, int exitcode,
 136                               int mustexit)
 137 {
 138         int status, n, ret = 0;
 139
 140         if(ptrace(PTRACE_CONT, pid, 0, 0) < 0)
 141                 fatal_perror("stop_ptraced_child : ptrace failed");
 142         CATCH_EINTR(n = waitpid(pid, &status, 0));
 143         if(!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {
 144                 int exit_with = WEXITSTATUS(status);
 145                 if (exit_with == 2)
 146                         non_fatal("check_ptrace : child exited with status 2. "
 147                                   "\nDisabling SYSEMU support.\n");
 148                 non_fatal("check_ptrace : child exited with exitcode %d, while "
 149                           "expecting %d; status 0x%x\n", exit_with,
 150                           exitcode, status);
 151                 if (mustexit)
 152                         exit(1);
 153                 ret = -1;
 154         }
 155
 156         if(munmap(stack, UM_KERN_PAGE_SIZE) < 0)
 157                 fatal_perror("check_ptrace : munmap failed");
 158         return ret;
 159 }
 160
 161 /* Changed only during early boot */
 162 int ptrace_faultinfo = 1;
 163 int ptrace_ldt = 1;
 164 int proc_mm = 1;
 165 int skas_needs_stub = 0;
 166
 167 static int __init skas0_cmd_param(char *str, int* add)
 168 {
 169         ptrace_faultinfo = proc_mm = 0;
 170         return 0;
 171 }
 172
 173 /* The two __uml_setup would conflict, without this stupid alias. */
 174
 175 static int __init mode_skas0_cmd_param(char *str, int* add)
 176         __attribute__((alias("skas0_cmd_param")));
 177
 178 __uml_setup("skas0", skas0_cmd_param,
 179                 "skas0\n"
 180                 "    Disables SKAS3 usage, so that SKAS0 is used, unless \n"
 181                 "    you specify mode=tt.\n\n");
 182
 183 __uml_setup("mode=skas0", mode_skas0_cmd_param,
 184                 "mode=skas0\n"
 185                 "    Disables SKAS3 usage, so that SKAS0 is used, unless you \n"
 186                 "    specify mode=tt. Note that this was recently added - on \n"
 187                 "    older kernels you must use simply \"skas0\".\n\n");
 188
 189 /* Changed only during early boot */
 190 static int force_sysemu_disabled = 0;
 191
 192 static int __init nosysemu_cmd_param(char *str, int* add)
 193 {
 194         force_sysemu_disabled = 1;
 195         return 0;
 196 }
 197
 198 __uml_setup("nosysemu", nosysemu_cmd_param,
 199 "nosysemu\n"
 200 "    Turns off syscall emulation patch for ptrace (SYSEMU) on.\n"
 201 "    SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n"
 202 "    behaviour of ptrace() and helps reducing host context switch rate.\n"
 203 "    To make it working, you need a kernel patch for your host, too.\n"
 204 "    See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n"
 205 "    information.\n\n");
 206
 207 static void __init check_sysemu(void)
 208 {
 209         void *stack;
 210         unsigned long regs[MAX_REG_NR];
 211         int pid, n, status, count=0;
 212
 213         non_fatal("Checking syscall emulation patch for ptrace...");
 214         sysemu_supported = 0;
 215         pid = start_ptraced_child(&stack);
 216
 217         if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0)
 218                 goto fail;
 219
 220         CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
 221         if (n < 0)
 222                 fatal_perror("check_sysemu : wait failed");
 223         if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
 224                 fatal("check_sysemu : expected SIGTRAP, got status = %d",
 225                       status);
 226
 227         if(ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
 228                 fatal_perror("check_sysemu : PTRACE_GETREGS failed");
 229         if(PT_SYSCALL_NR(regs) != __NR_getpid){
 230                 non_fatal("check_sysemu got system call number %d, "
 231                           "expected %d...", PT_SYSCALL_NR(regs), __NR_getpid);
 232                 goto fail;
 233         }
 234
 235         n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, os_getpid());
 236         if(n < 0){
 237                 non_fatal("check_sysemu : failed to modify system call "
 238                           "return");
 239                 goto fail;
 240         }
 241
 242         if (stop_ptraced_child(pid, stack, 0, 0) < 0)
 243                 goto fail_stopped;
 244
 245         sysemu_supported = 1;
 246         non_fatal("OK\n");
 247         set_using_sysemu(!force_sysemu_disabled);
 248
 249         non_fatal("Checking advanced syscall emulation patch for ptrace...");
 250         pid = start_ptraced_child(&stack);
 251
 252         if((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
 253                    (void *) PTRACE_O_TRACESYSGOOD) < 0))
 254                 fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed");
 255
 256         while(1){
 257                 count++;
 258                 if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
 259                         goto fail;
 260                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
 261                 if(n < 0)
 262                         fatal_perror("check_ptrace : wait failed");
 263
 264                 if(WIFSTOPPED(status) && (WSTOPSIG(status) == (SIGTRAP|0x80))){
 265                         if (!count)
 266                                 fatal("check_ptrace : SYSEMU_SINGLESTEP "
 267                                       "doesn't singlestep");
 268                         n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
 269                                    os_getpid());
 270                         if(n < 0)
 271                                 fatal_perror("check_sysemu : failed to modify "
 272                                              "system call return");
 273                         break;
 274                 }
 275                 else if(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP))
 276                         count++;
 277                 else
 278                         fatal("check_ptrace : expected SIGTRAP or "
 279                               "(SIGTRAP | 0x80), got status = %d", status);
 280         }
 281         if (stop_ptraced_child(pid, stack, 0, 0) < 0)
 282                 goto fail_stopped;
 283
 284         sysemu_supported = 2;
 285         non_fatal("OK\n");
 286
 287         if ( !force_sysemu_disabled )
 288                 set_using_sysemu(sysemu_supported);
 289         return;
 290
 291 fail:
 292         stop_ptraced_child(pid, stack, 1, 0);
 293 fail_stopped:
 294         non_fatal("missing\n");
 295 }
 296
 297 static void __init check_ptrace(void)
 298 {
 299         void *stack;
 300         int pid, syscall, n, status;
 301
 302         non_fatal("Checking that ptrace can change system call numbers...");
 303         pid = start_ptraced_child(&stack);
 304
 305         if((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
 306                    (void *) PTRACE_O_TRACESYSGOOD) < 0))
 307                 fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed");
 308
 309         while(1){
 310                 if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
 311                         fatal_perror("check_ptrace : ptrace failed");
 312
 313                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
 314                 if(n < 0)
 315                         fatal_perror("check_ptrace : wait failed");
 316
 317                 if(!WIFSTOPPED(status) ||
 318                    (WSTOPSIG(status) != (SIGTRAP | 0x80)))
 319                         fatal("check_ptrace : expected (SIGTRAP|0x80), "
 320                                "got status = %d", status);
 321
 322                 syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET,
 323                                  0);
 324                 if(syscall == __NR_getpid){
 325                         n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
 326                                    __NR_getppid);
 327                         if(n < 0)
 328                                 fatal_perror("check_ptrace : failed to modify "
 329                                              "system call");
 330                         break;
 331                 }
 332         }
 333         stop_ptraced_child(pid, stack, 0, 1);
 334         non_fatal("OK\n");
 335         check_sysemu();
 336 }
 337
 338 extern void check_tmpexec(void);
 339
 340 static void __init check_coredump_limit(void)
 341 {
 342         struct rlimit lim;
 343         int err = getrlimit(RLIMIT_CORE, &lim);
 344
 345         if(err){
 346                 perror("Getting core dump limit");
 347                 return;
 348         }
 349
 350         printf("Core dump limits :\n\tsoft - ");
 351         if(lim.rlim_cur == RLIM_INFINITY)
 352                 printf("NONE\n");
 353         else printf("%lu\n", lim.rlim_cur);
 354
 355         printf("\thard - ");
 356         if(lim.rlim_max == RLIM_INFINITY)
 357                 printf("NONE\n");
 358         else printf("%lu\n", lim.rlim_max);
 359 }
 360
 361 void __init os_early_checks(void)
 362 {
 363         /* Print out the core dump limits early */
 364         check_coredump_limit();
 365
 366         check_ptrace();
 367
 368         /* Need to check this early because mmapping happens before the
 369          * kernel is running.
 370          */
 371         check_tmpexec();
 372 }
 373
 374 static int __init noprocmm_cmd_param(char *str, int* add)
 375 {
 376         proc_mm = 0;
 377         return 0;
 378 }
 379
 380 __uml_setup("noprocmm", noprocmm_cmd_param,
 381 "noprocmm\n"
 382 "    Turns off usage of /proc/mm, even if host supports it.\n"
 383 "    To support /proc/mm, the host needs to be patched using\n"
 384 "    the current skas3 patch.\n\n");
 385
 386 static int __init noptracefaultinfo_cmd_param(char *str, int* add)
 387 {
 388         ptrace_faultinfo = 0;
 389         return 0;
 390 }
 391
 392 __uml_setup("noptracefaultinfo", noptracefaultinfo_cmd_param,
 393 "noptracefaultinfo\n"
 394 "    Turns off usage of PTRACE_FAULTINFO, even if host supports\n"
 395 "    it. To support PTRACE_FAULTINFO, the host needs to be patched\n"
 396 "    using the current skas3 patch.\n\n");
 397
 398 static int __init noptraceldt_cmd_param(char *str, int* add)
 399 {
 400         ptrace_ldt = 0;
 401         return 0;
 402 }
 403
 404 __uml_setup("noptraceldt", noptraceldt_cmd_param,
 405 "noptraceldt\n"
 406 "    Turns off usage of PTRACE_LDT, even if host supports it.\n"
 407 "    To support PTRACE_LDT, the host needs to be patched using\n"
 408 "    the current skas3 patch.\n\n");
 409
 410 #ifdef UML_CONFIG_MODE_SKAS
 411 static inline void check_skas3_ptrace_faultinfo(void)
 412 {
 413         struct ptrace_faultinfo fi;
 414         void *stack;
 415         int pid, n;
 416
 417         non_fatal("  - PTRACE_FAULTINFO...");
 418         pid = start_ptraced_child(&stack);
 419
 420         n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
 421         if (n < 0) {
 422                 ptrace_faultinfo = 0;
 423                 if(errno == EIO)
 424                         non_fatal("not found\n");
 425                 else
 426                         perror("not found");
 427         }
 428         else {
 429                 if (!ptrace_faultinfo)
 430                         non_fatal("found but disabled on command line\n");
 431                 else
 432                         non_fatal("found\n");
 433         }
 434
 435         init_registers(pid);
 436         stop_ptraced_child(pid, stack, 1, 1);
 437 }
 438
 439 static inline void check_skas3_ptrace_ldt(void)
 440 {
 441 #ifdef PTRACE_LDT
 442         void *stack;
 443         int pid, n;
 444         unsigned char ldtbuf[40];
 445         struct ptrace_ldt ldt_op = (struct ptrace_ldt) {
 446                 .func = 2, /* read default ldt */
 447                 .ptr = ldtbuf,
 448                 .bytecount = sizeof(ldtbuf)};
 449
 450         non_fatal("  - PTRACE_LDT...");
 451         pid = start_ptraced_child(&stack);
 452
 453         n = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op);
 454         if (n < 0) {
 455                 if(errno == EIO)
 456                         non_fatal("not found\n");
 457                 else {
 458                         perror("not found");
 459                 }
 460                 ptrace_ldt = 0;
 461         }
 462         else {
 463                 if(ptrace_ldt)
 464                         non_fatal("found\n");
 465                 else
 466                         non_fatal("found, but use is disabled\n");
 467         }
 468
 469         stop_ptraced_child(pid, stack, 1, 1);
 470 #else
 471         /* PTRACE_LDT might be disabled via cmdline option.
 472          * We want to override this, else we might use the stub
 473          * without real need
 474          */
 475         ptrace_ldt = 1;
 476 #endif
 477 }
 478
 479 static inline void check_skas3_proc_mm(void)
 480 {
 481         non_fatal("  - /proc/mm...");
 482         if (access("/proc/mm", W_OK) < 0) {
 483                 proc_mm = 0;
 484                 perror("not found");
 485         }
 486         else {
 487                 if (!proc_mm)
 488                         non_fatal("found but disabled on command line\n");
 489                 else
 490                         non_fatal("found\n");
 491         }
 492 }
 493
 494 int can_do_skas(void)
 495 {
 496         non_fatal("Checking for the skas3 patch in the host:\n");
 497
 498         check_skas3_proc_mm();
 499         check_skas3_ptrace_faultinfo();
 500         check_skas3_ptrace_ldt();
 501
 502         if(!proc_mm || !ptrace_faultinfo || !ptrace_ldt)
 503                 skas_needs_stub = 1;
 504
 505         return 1;
 506 }
 507 #else
 508 int can_do_skas(void)
 509 {
 510         return 0;
 511 }
 512 #endif
 513
 514 int __init parse_iomem(char *str, int *add)
 515 {
 516         struct iomem_region *new;
 517         struct stat64 buf;
 518         char *file, *driver;
 519         int fd, size;
 520
 521         driver = str;
 522         file = strchr(str,',');
 523         if(file == NULL){
 524                 printf("parse_iomem : failed to parse iomem\n");
 525                 goto out;
 526         }
 527         *file = '\0';
 528         file++;
 529         fd = open(file, O_RDWR, 0);
 530         if(fd < 0){
 531                 os_print_error(fd, "parse_iomem - Couldn't open io file");
 532                 goto out;
 533         }
 534
 535         if(fstat64(fd, &buf) < 0){
 536                 perror("parse_iomem - cannot stat_fd file");
 537                 goto out_close;
 538         }
 539
 540         new = malloc(sizeof(*new));
 541         if(new == NULL){
 542                 perror("Couldn't allocate iomem_region struct");
 543                 goto out_close;
 544         }
 545
 546         size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1);
 547
 548         *new = ((struct iomem_region) { .next           = iomem_regions,
 549                                         .driver         = driver,
 550                                         .fd             = fd,
 551                                         .size           = size,
 552                                         .phys           = 0,
 553                                         .virt           = 0 });
 554         iomem_regions = new;
 555         iomem_size += new->size + UM_KERN_PAGE_SIZE;
 556
 557         return 0;
 558  out_close:
 559         close(fd);
 560  out:
 561         return 1;
 562 }