arch/um/kernel/tt/tracer.c

   1 /*
   2  * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include <stdio.h>
   7 #include <stdlib.h>
   8 #include <stdarg.h>
   9 #include <unistd.h>
  10 #include <signal.h>
  11 #include <errno.h>
  12 #include <sched.h>
  13 #include <string.h>
  14 #include <sys/mman.h>
  15 #include <sys/ptrace.h>
  16 #include <linux/ptrace.h>
  17 #include <sys/time.h>
  18 #include <sys/wait.h>
  19 #include "user.h"
  20 #include "sysdep/ptrace.h"
  21 #include "sigcontext.h"
  22 #include "sysdep/sigcontext.h"
  23 #include "os.h"
  24 #include "signal_user.h"
  25 #include "user_util.h"
  26 #include "mem_user.h"
  27 #include "process.h"
  28 #include "kern_util.h"
  29 #include "chan_user.h"
  30 #include "ptrace_user.h"
  31 #include "mode.h"
  32 #include "tt.h"
  33
  34 static int tracer_winch[2];
  35
  36 int is_tracer_winch(int pid, int fd, void *data)
  37 {
  38         if(pid != tracing_pid)
  39                 return(0);
  40
  41         register_winch_irq(tracer_winch[0], fd, -1, data);
  42         return(1);
  43 }
  44
  45 static void tracer_winch_handler(int sig)
  46 {
  47         int n;
  48         char c = 1;
  49
  50         n = os_write_file(tracer_winch[1], &c, sizeof(c));
  51         if(n != sizeof(c))
  52                 printk("tracer_winch_handler - write failed, err = %d\n", -n);
  53 }
  54
  55 /* Called only by the tracing thread during initialization */
  56
  57 static void setup_tracer_winch(void)
  58 {
  59         int err;
  60
  61         err = os_pipe(tracer_winch, 1, 1);
  62         if(err < 0){
  63                 printk("setup_tracer_winch : os_pipe failed, err = %d\n", -err);
  64                 return;
  65         }
  66         signal(SIGWINCH, tracer_winch_handler);
  67 }
  68
  69 void attach_process(int pid)
  70 {
  71         if((ptrace(PTRACE_ATTACH, pid, 0, 0) < 0) ||
  72            (ptrace(PTRACE_CONT, pid, 0, 0) < 0))
  73                 tracer_panic("OP_FORK failed to attach pid");
  74         wait_for_stop(pid, SIGSTOP, PTRACE_CONT, NULL);
  75         if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0)
  76                 tracer_panic("OP_FORK: PTRACE_SETOPTIONS failed, errno = %d", errno);
  77         if(ptrace(PTRACE_CONT, pid, 0, 0) < 0)
  78                 tracer_panic("OP_FORK failed to continue process");
  79 }
  80
  81 void tracer_panic(char *format, ...)
  82 {
  83         va_list ap;
  84
  85         va_start(ap, format);
  86         vprintf(format, ap);
  87         va_end(ap);
  88         printf("\n");
  89         while(1) pause();
  90 }
  91
  92 static void tracer_segv(int sig, struct sigcontext sc)
  93 {
  94         printf("Tracing thread segfault at address 0x%lx, ip 0x%lx\n",
  95                SC_FAULT_ADDR(&sc), SC_IP(&sc));
  96         while(1)
  97                 pause();
  98 }
  99
 100 /* Changed early in boot, and then only read */
 101 int debug = 0;
 102 int debug_stop = 1;
 103 int debug_parent = 0;
 104 int honeypot = 0;
 105
 106 static int signal_tramp(void *arg)
 107 {
 108         int (*proc)(void *);
 109
 110         if(honeypot && munmap((void *) (host_task_size - 0x10000000),
 111                               0x10000000))
 112                 panic("Unmapping stack failed");
 113         if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0)
 114                 panic("ptrace PTRACE_TRACEME failed");
 115         os_stop_process(os_getpid());
 116         change_sig(SIGWINCH, 0);
 117         signal(SIGUSR1, SIG_IGN);
 118         change_sig(SIGCHLD, 0);
 119         signal(SIGSEGV, (__sighandler_t) sig_handler);
 120         set_cmdline("(idle thread)");
 121         set_init_pid(os_getpid());
 122         proc = arg;
 123         return((*proc)(NULL));
 124 }
 125
 126 static void sleeping_process_signal(int pid, int sig)
 127 {
 128         switch(sig){
 129         /* These two result from UML being ^Z-ed and bg-ed.  PTRACE_CONT is
 130          * right because the process must be in the kernel already.
 131          */
 132         case SIGCONT:
 133         case SIGTSTP:
 134                 if(ptrace(PTRACE_CONT, pid, 0, sig) < 0)
 135                         tracer_panic("sleeping_process_signal : Failed to "
 136                                      "continue pid %d, signal = %d, "
 137                                      "errno = %d\n", pid, sig, errno);
 138                 break;
 139
 140         /* This happens when the debugger (e.g. strace) is doing system call
 141          * tracing on the kernel.  During a context switch, the current task
 142          * will be set to the incoming process and the outgoing process will
 143          * hop into write and then read.  Since it's not the current process
 144          * any more, the trace of those will land here.  So, we need to just
 145          * PTRACE_SYSCALL it.
 146          */
 147         case (SIGTRAP + 0x80):
 148                 if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
 149                         tracer_panic("sleeping_process_signal : Failed to "
 150                                      "PTRACE_SYSCALL pid %d, errno = %d\n",
 151                                      pid, errno);
 152                 break;
 153         case SIGSTOP:
 154                 break;
 155         default:
 156                 tracer_panic("sleeping process %d got unexpected "
 157                              "signal : %d\n", pid, sig);
 158                 break;
 159         }
 160 }
 161
 162 /* Accessed only by the tracing thread */
 163 int debugger_pid = -1;
 164 int debugger_parent = -1;
 165 int debugger_fd = -1;
 166 int gdb_pid = -1;
 167
 168 struct {
 169         int pid;
 170         int signal;
 171         unsigned long addr;
 172         struct timeval time;
 173 } signal_record[1024][32];
 174
 175 int signal_index[32];
 176 int nsignals = 0;
 177 int debug_trace = 0;
 178 extern int io_nsignals, io_count, intr_count;
 179
 180 extern void signal_usr1(int sig);
 181
 182 int tracing_pid = -1;
 183
 184 int tracer(int (*init_proc)(void *), void *sp)
 185 {
 186         void *task = NULL;
 187         unsigned long eip = 0;
 188         int status, pid = 0, sig = 0, cont_type, tracing = 0, op = 0;
 189         int last_index, proc_id = 0, n, err, old_tracing = 0, strace = 0;
 190         int local_using_sysemu = 0;
 191
 192         signal(SIGPIPE, SIG_IGN);
 193         setup_tracer_winch();
 194         tracing_pid = os_getpid();
 195         printf("tracing thread pid = %d\n", tracing_pid);
 196
 197         pid = clone(signal_tramp, sp, CLONE_FILES | SIGCHLD, init_proc);
 198         CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
 199         if(n < 0){
 200                 printf("waitpid on idle thread failed, errno = %d\n", errno);
 201                 exit(1);
 202         }
 203         if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0) {
 204                 printf("Failed to PTRACE_SETOPTIONS for idle thread, errno = %d\n", errno);
 205                 exit(1);
 206         }
 207         if((ptrace(PTRACE_CONT, pid, 0, 0) < 0)){
 208                 printf("Failed to continue idle thread, errno = %d\n", errno);
 209                 exit(1);
 210         }
 211
 212         signal(SIGSEGV, (sighandler_t) tracer_segv);
 213         signal(SIGUSR1, signal_usr1);
 214         if(debug_trace){
 215                 printf("Tracing thread pausing to be attached\n");
 216                 stop();
 217         }
 218         if(debug){
 219                 if(gdb_pid != -1)
 220                         debugger_pid = attach_debugger(pid, gdb_pid, 1);
 221                 else debugger_pid = init_ptrace_proxy(pid, 1, debug_stop);
 222                 if(debug_parent){
 223                         debugger_parent = os_process_parent(debugger_pid);
 224                         init_parent_proxy(debugger_parent);
 225                         err = attach(debugger_parent);
 226                         if(err){
 227                                 printf("Failed to attach debugger parent %d, "
 228                                        "errno = %d\n", debugger_parent, -err);
 229                                 debugger_parent = -1;
 230                         }
 231                         else {
 232                                 if(ptrace(PTRACE_SYSCALL, debugger_parent,
 233                                           0, 0) < 0){
 234                                         printf("Failed to continue debugger "
 235                                                "parent, errno = %d\n", errno);
 236                                         debugger_parent = -1;
 237                                 }
 238                         }
 239                 }
 240         }
 241         set_cmdline("(tracing thread)");
 242         while(1){
 243                 CATCH_EINTR(pid = waitpid(-1, &status, WUNTRACED));
 244                 if(pid <= 0){
 245                         if(errno != ECHILD){
 246                                 printf("wait failed - errno = %d\n", errno);
 247                         }
 248                         continue;
 249                 }
 250                 if(pid == debugger_pid){
 251                         int cont = 0;
 252
 253                         if(WIFEXITED(status) || WIFSIGNALED(status))
 254                                 debugger_pid = -1;
 255                         /* XXX Figure out how to deal with gdb and SMP */
 256                         else cont = debugger_signal(status, cpu_tasks[0].pid);
 257                         if(cont == PTRACE_SYSCALL) strace = 1;
 258                         continue;
 259                 }
 260                 else if(pid == debugger_parent){
 261                         debugger_parent_signal(status, pid);
 262                         continue;
 263                 }
 264                 nsignals++;
 265                 if(WIFEXITED(status)) ;
 266 #ifdef notdef
 267                 {
 268                         printf("Child %d exited with status %d\n", pid,
 269                                WEXITSTATUS(status));
 270                 }
 271 #endif
 272                 else if(WIFSIGNALED(status)){
 273                         sig = WTERMSIG(status);
 274                         if(sig != 9){
 275                                 printf("Child %d exited with signal %d\n", pid,
 276                                        sig);
 277                         }
 278                 }
 279                 else if(WIFSTOPPED(status)){
 280                         proc_id = pid_to_processor_id(pid);
 281                         sig = WSTOPSIG(status);
 282                         if(signal_index[proc_id] == 1024){
 283                                 signal_index[proc_id] = 0;
 284                                 last_index = 1023;
 285                         }
 286                         else last_index = signal_index[proc_id] - 1;
 287                         if(((sig == SIGPROF) || (sig == SIGVTALRM) ||
 288                             (sig == SIGALRM)) &&
 289                            (signal_record[proc_id][last_index].signal == sig)&&
 290                            (signal_record[proc_id][last_index].pid == pid))
 291                                 signal_index[proc_id] = last_index;
 292                         signal_record[proc_id][signal_index[proc_id]].pid = pid;
 293                         gettimeofday(&signal_record[proc_id][signal_index[proc_id]].time, NULL);
 294                         eip = ptrace(PTRACE_PEEKUSER, pid, PT_IP_OFFSET, 0);
 295                         signal_record[proc_id][signal_index[proc_id]].addr = eip;
 296                         signal_record[proc_id][signal_index[proc_id]++].signal = sig;
 297
 298                         if(proc_id == -1){
 299                                 sleeping_process_signal(pid, sig);
 300                                 continue;
 301                         }
 302
 303                         task = cpu_tasks[proc_id].task;
 304                         tracing = is_tracing(task);
 305                         old_tracing = tracing;
 306
 307                         /* Assume: no syscall, when coming from user */
 308                         if ( tracing )
 309                                 do_sigtrap(task);
 310
 311                         switch(sig){
 312                         case SIGUSR1:
 313                                 sig = 0;
 314                                 op = do_proc_op(task, proc_id);
 315                                 switch(op){
 316                                 /*
 317                                  * This is called when entering user mode; after
 318                                  * this, we start intercepting syscalls.
 319                                  *
 320                                  * In fact, a process is started in kernel mode,
 321                                  * so with is_tracing() == 0 (and that is reset
 322                                  * when executing syscalls, since UML kernel has
 323                                  * the right to do syscalls);
 324                                  */
 325                                 case OP_TRACE_ON:
 326                                         arch_leave_kernel(task, pid);
 327                                         tracing = 1;
 328                                         break;
 329                                 case OP_REBOOT:
 330                                 case OP_HALT:
 331                                         unmap_physmem();
 332                                         kmalloc_ok = 0;
 333                                         os_kill_ptraced_process(pid, 0);
 334                                         /* Now let's reap remaining zombies */
 335                                         errno = 0;
 336                                         do {
 337                                                 waitpid(-1, &status,
 338                                                         WUNTRACED);
 339                                         } while (errno != ECHILD);
 340                                         return(op == OP_REBOOT);
 341                                 case OP_NONE:
 342                                         printf("Detaching pid %d\n", pid);
 343                                         detach(pid, SIGSTOP);
 344                                         continue;
 345                                 default:
 346                                         break;
 347                                 }
 348                                 /* OP_EXEC switches host processes on us,
 349                                  * we want to continue the new one.
 350                                  */
 351                                 pid = cpu_tasks[proc_id].pid;
 352                                 break;
 353                         case (SIGTRAP + 0x80):
 354                                 if(!tracing && (debugger_pid != -1)){
 355                                         child_signal(pid, status & 0x7fff);
 356                                         continue;
 357                                 }
 358                                 tracing = 0;
 359                                 /* local_using_sysemu has been already set
 360                                  * below, since if we are here, is_tracing() on
 361                                  * the traced task was 1, i.e. the process had
 362                                  * already run through one iteration of the
 363                                  * loop which executed a OP_TRACE_ON request.*/
 364                                 do_syscall(task, pid, local_using_sysemu);
 365                                 sig = SIGUSR2;
 366                                 break;
 367                         case SIGTRAP:
 368                                 if(!tracing && (debugger_pid != -1)){
 369                                         child_signal(pid, status);
 370                                         continue;
 371                                 }
 372                                 tracing = 0;
 373                                 break;
 374                         case SIGPROF:
 375                                 if(tracing) sig = 0;
 376                                 break;
 377                         case SIGCHLD:
 378                         case SIGHUP:
 379                                 sig = 0;
 380                                 break;
 381                         case SIGSEGV:
 382                         case SIGIO:
 383                         case SIGALRM:
 384                         case SIGVTALRM:
 385                         case SIGFPE:
 386                         case SIGBUS:
 387                         case SIGILL:
 388                         case SIGWINCH:
 389
 390                         default:
 391                                 tracing = 0;
 392                                 break;
 393                         }
 394                         set_tracing(task, tracing);
 395
 396                         if(!tracing && old_tracing)
 397                                 arch_enter_kernel(task, pid);
 398
 399                         if(!tracing && (debugger_pid != -1) && (sig != 0) &&
 400                                 (sig != SIGALRM) && (sig != SIGVTALRM) &&
 401                                 (sig != SIGSEGV) && (sig != SIGTRAP) &&
 402                                 (sig != SIGUSR2) && (sig != SIGIO) &&
 403                                 (sig != SIGFPE)){
 404                                 child_signal(pid, status);
 405                                 continue;
 406                         }
 407
 408                         local_using_sysemu = get_using_sysemu();
 409
 410                         if(tracing)
 411                                 cont_type = SELECT_PTRACE_OPERATION(local_using_sysemu,
 412                                                                     singlestepping(task));
 413                         else if((debugger_pid != -1) && strace)
 414                                 cont_type = PTRACE_SYSCALL;
 415                         else
 416                                 cont_type = PTRACE_CONT;
 417
 418                         if(ptrace(cont_type, pid, 0, sig) != 0){
 419                                 tracer_panic("ptrace failed to continue "
 420                                              "process - errno = %d\n",
 421                                              errno);
 422                         }
 423                 }
 424         }
 425         return(0);
 426 }
 427
 428 static int __init uml_debug_setup(char *line, int *add)
 429 {
 430         char *next;
 431
 432         debug = 1;
 433         *add = 0;
 434         if(*line != '=') return(0);
 435         line++;
 436
 437         while(line != NULL){
 438                 next = strchr(line, ',');
 439                 if(next) *next++ = '\0';
 440
 441                 if(!strcmp(line, "go")) debug_stop = 0;
 442                 else if(!strcmp(line, "parent")) debug_parent = 1;
 443                 else printf("Unknown debug option : '%s'\n", line);
 444
 445                 line = next;
 446         }
 447         return(0);
 448 }
 449
 450 __uml_setup("debug", uml_debug_setup,
 451 "debug\n"
 452 "    Starts up the kernel under the control of gdb. See the \n"
 453 "    kernel debugging tutorial and the debugging session pages\n"
 454 "    at http://user-mode-linux.sourceforge.net/ for more information.\n\n"
 455 );
 456
 457 static int __init uml_debugtrace_setup(char *line, int *add)
 458 {
 459         debug_trace = 1;
 460         return 0;
 461 }
 462 __uml_setup("debugtrace", uml_debugtrace_setup,
 463 "debugtrace\n"
 464 "    Causes the tracing thread to pause until it is attached by a\n"
 465 "    debugger and continued.  This is mostly for debugging crashes\n"
 466 "    early during boot, and should be pretty much obsoleted by\n"
 467 "    the debug switch.\n\n"
 468 );
 469
 470 static int __init uml_honeypot_setup(char *line, int *add)
 471 {
 472         jail_setup("", add);
 473         honeypot = 1;
 474         return 0;
 475 }
 476 __uml_setup("honeypot", uml_honeypot_setup,
 477 "honeypot\n"
 478 "    This makes UML put process stacks in the same location as they are\n"
 479 "    on the host, allowing expoits such as stack smashes to work against\n"
 480 "    UML.  This implies 'jail'.\n\n"
 481 );
 482
 483 /*
 484  * Overrides for Emacs so that we follow Linus's tabbing style.
 485  * Emacs will notice this stuff at the end of the file and automatically
 486  * adjust the settings for this buffer only.  This must remain at the end
 487  * of the file.
 488  * ---------------------------------------------------------------------------
 489  * Local variables:
 490  * c-file-style: "linux"
 491  * End:
 492  */