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