arch/x86_64/kernel/ptrace.c

   1 /* ptrace.c */
   2 /* By Ross Biro 1/23/92 */
   3 /*
   4  * Pentium III FXSR, SSE support
   5  *      Gareth Hughes <gareth@valinux.com>, May 2000
   6  *
   7  * x86-64 port 2000-2002 Andi Kleen
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/sched.h>
  12 #include <linux/mm.h>
  13 #include <linux/smp.h>
  14 #include <linux/smp_lock.h>
  15 #include <linux/errno.h>
  16 #include <linux/ptrace.h>
  17 #include <linux/user.h>
  18 #include <linux/security.h>
  19 #include <linux/audit.h>
  20 #include <linux/seccomp.h>
  21
  22 #include <asm/uaccess.h>
  23 #include <asm/pgtable.h>
  24 #include <asm/system.h>
  25 #include <asm/processor.h>
  26 #include <asm/i387.h>
  27 #include <asm/debugreg.h>
  28 #include <asm/ldt.h>
  29 #include <asm/desc.h>
  30 #include <asm/proto.h>
  31 #include <asm/ia32.h>
  32
  33 /*
  34  * does not yet catch signals sent when the child dies.
  35  * in exit.c or in signal.c.
  36  */
  37
  38 /* determines which flags the user has access to. */
  39 /* 1 = access 0 = no access */
  40 #define FLAG_MASK 0x44dd5UL
  41
  42 /* set's the trap flag. */
  43 #define TRAP_FLAG 0x100UL
  44
  45 /*
  46  * eflags and offset of eflags on child stack..
  47  */
  48 #define EFLAGS offsetof(struct pt_regs, eflags)
  49 #define EFL_OFFSET ((int)(EFLAGS-sizeof(struct pt_regs)))
  50
  51 /*
  52  * this routine will get a word off of the processes privileged stack.
  53  * the offset is how far from the base addr as stored in the TSS.
  54  * this routine assumes that all the privileged stacks are in our
  55  * data space.
  56  */
  57 static inline unsigned long get_stack_long(struct task_struct *task, int offset)
  58 {
  59         unsigned char *stack;
  60
  61         stack = (unsigned char *)task->thread.rsp0;
  62         stack += offset;
  63         return (*((unsigned long *)stack));
  64 }
  65
  66 /*
  67  * this routine will put a word on the processes privileged stack.
  68  * the offset is how far from the base addr as stored in the TSS.
  69  * this routine assumes that all the privileged stacks are in our
  70  * data space.
  71  */
  72 static inline long put_stack_long(struct task_struct *task, int offset,
  73         unsigned long data)
  74 {
  75         unsigned char * stack;
  76
  77         stack = (unsigned char *) task->thread.rsp0;
  78         stack += offset;
  79         *(unsigned long *) stack = data;
  80         return 0;
  81 }
  82
  83 /*
  84  * Called by kernel/ptrace.c when detaching..
  85  *
  86  * Make sure the single step bit is not set.
  87  */
  88 void ptrace_disable(struct task_struct *child)
  89 {
  90         long tmp;
  91
  92         clear_tsk_thread_flag(child, TIF_SINGLESTEP);
  93         tmp = get_stack_long(child, EFL_OFFSET) & ~TRAP_FLAG;
  94         put_stack_long(child, EFL_OFFSET, tmp);
  95 }
  96
  97 static int putreg(struct task_struct *child,
  98         unsigned long regno, unsigned long value)
  99 {
 100         unsigned long tmp;
 101
 102         /* Some code in the 64bit emulation may not be 64bit clean.
 103            Don't take any chances. */
 104         if (test_tsk_thread_flag(child, TIF_IA32))
 105                 value &= 0xffffffff;
 106         switch (regno) {
 107                 case offsetof(struct user_regs_struct,fs):
 108                         if (value && (value & 3) != 3)
 109                                 return -EIO;
 110                         child->thread.fsindex = value & 0xffff;
 111                         return 0;
 112                 case offsetof(struct user_regs_struct,gs):
 113                         if (value && (value & 3) != 3)
 114                                 return -EIO;
 115                         child->thread.gsindex = value & 0xffff;
 116                         return 0;
 117                 case offsetof(struct user_regs_struct,ds):
 118                         if (value && (value & 3) != 3)
 119                                 return -EIO;
 120                         child->thread.ds = value & 0xffff;
 121                         return 0;
 122                 case offsetof(struct user_regs_struct,es):
 123                         if (value && (value & 3) != 3)
 124                                 return -EIO;
 125                         child->thread.es = value & 0xffff;
 126                         return 0;
 127                 case offsetof(struct user_regs_struct,ss):
 128                         if ((value & 3) != 3)
 129                                 return -EIO;
 130                         value &= 0xffff;
 131                         return 0;
 132                 case offsetof(struct user_regs_struct,fs_base):
 133                         if (!((value >> 48) == 0 || (value >> 48) == 0xffff))
 134                                 return -EIO;
 135                         child->thread.fs = value;
 136                         return 0;
 137                 case offsetof(struct user_regs_struct,gs_base):
 138                         if (!((value >> 48) == 0 || (value >> 48) == 0xffff))
 139                                 return -EIO;
 140                         child->thread.gs = value;
 141                         return 0;
 142                 case offsetof(struct user_regs_struct, eflags):
 143                         value &= FLAG_MASK;
 144                         tmp = get_stack_long(child, EFL_OFFSET);
 145                         tmp &= ~FLAG_MASK;
 146                         value |= tmp;
 147                         break;
 148                 case offsetof(struct user_regs_struct,cs):
 149                         if ((value & 3) != 3)
 150                                 return -EIO;
 151                         value &= 0xffff;
 152                         break;
 153         }
 154         put_stack_long(child, regno - sizeof(struct pt_regs), value);
 155         return 0;
 156 }
 157
 158 static unsigned long getreg(struct task_struct *child, unsigned long regno)
 159 {
 160         unsigned long val;
 161         switch (regno) {
 162                 case offsetof(struct user_regs_struct, fs):
 163                         return child->thread.fsindex;
 164                 case offsetof(struct user_regs_struct, gs):
 165                         return child->thread.gsindex;
 166                 case offsetof(struct user_regs_struct, ds):
 167                         return child->thread.ds;
 168                 case offsetof(struct user_regs_struct, es):
 169                         return child->thread.es;
 170                 case offsetof(struct user_regs_struct, fs_base):
 171                         return child->thread.fs;
 172                 case offsetof(struct user_regs_struct, gs_base):
 173                         return child->thread.gs;
 174                 default:
 175                         regno = regno - sizeof(struct pt_regs);
 176                         val = get_stack_long(child, regno);
 177                         if (test_tsk_thread_flag(child, TIF_IA32))
 178                                 val &= 0xffffffff;
 179                         return val;
 180         }
 181
 182 }
 183
 184 asmlinkage long sys_ptrace(long request, long pid, unsigned long addr, long data)
 185 {
 186         struct task_struct *child;
 187         long i, ret;
 188         unsigned ui;
 189
 190         /* This lock_kernel fixes a subtle race with suid exec */
 191         lock_kernel();
 192         ret = -EPERM;
 193         if (request == PTRACE_TRACEME) {
 194                 /* are we already being traced? */
 195                 if (current->ptrace & PT_PTRACED)
 196                         goto out;
 197                 ret = security_ptrace(current->parent, current);
 198                 if (ret)
 199                         goto out;
 200                 /* set the ptrace bit in the process flags. */
 201                 current->ptrace |= PT_PTRACED;
 202                 ret = 0;
 203                 goto out;
 204         }
 205         ret = -ESRCH;
 206         read_lock(&tasklist_lock);
 207         child = find_task_by_pid(pid);
 208         if (child)
 209                 get_task_struct(child);
 210         read_unlock(&tasklist_lock);
 211         if (!child)
 212                 goto out;
 213
 214         ret = -EPERM;
 215         if (pid == 1)           /* you may not mess with init */
 216                 goto out_tsk;
 217
 218         if (request == PTRACE_ATTACH) {
 219                 ret = ptrace_attach(child);
 220                 goto out_tsk;
 221         }
 222         ret = ptrace_check_attach(child, request == PTRACE_KILL);
 223         if (ret < 0)
 224                 goto out_tsk;
 225
 226         switch (request) {
 227         /* when I and D space are separate, these will need to be fixed. */
 228         case PTRACE_PEEKTEXT: /* read word at location addr. */
 229         case PTRACE_PEEKDATA: {
 230                 unsigned long tmp;
 231                 int copied;
 232
 233                 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 234                 ret = -EIO;
 235                 if (copied != sizeof(tmp))
 236                         break;
 237                 ret = put_user(tmp,(unsigned long __user *) data);
 238                 break;
 239         }
 240
 241         /* read the word at location addr in the USER area. */
 242         case PTRACE_PEEKUSR: {
 243                 unsigned long tmp;
 244
 245                 ret = -EIO;
 246                 if ((addr & 7) ||
 247                     addr > sizeof(struct user) - 7)
 248                         break;
 249
 250                 switch (addr) {
 251                 case 0 ... sizeof(struct user_regs_struct):
 252                         tmp = getreg(child, addr);
 253                         break;
 254                 case offsetof(struct user, u_debugreg[0]):
 255                         tmp = child->thread.debugreg0;
 256                         break;
 257                 case offsetof(struct user, u_debugreg[1]):
 258                         tmp = child->thread.debugreg1;
 259                         break;
 260                 case offsetof(struct user, u_debugreg[2]):
 261                         tmp = child->thread.debugreg2;
 262                         break;
 263                 case offsetof(struct user, u_debugreg[3]):
 264                         tmp = child->thread.debugreg3;
 265                         break;
 266                 case offsetof(struct user, u_debugreg[6]):
 267                         tmp = child->thread.debugreg6;
 268                         break;
 269                 case offsetof(struct user, u_debugreg[7]):
 270                         tmp = child->thread.debugreg7;
 271                         break;
 272                 default:
 273                         tmp = 0;
 274                         break;
 275                 }
 276                 ret = put_user(tmp,(unsigned long __user *) data);
 277                 break;
 278         }
 279
 280         /* when I and D space are separate, this will have to be fixed. */
 281         case PTRACE_POKETEXT: /* write the word at location addr. */
 282         case PTRACE_POKEDATA:
 283                 ret = 0;
 284                 if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
 285                         break;
 286                 ret = -EIO;
 287                 break;
 288
 289         case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
 290                 ret = -EIO;
 291                 if ((addr & 7) ||
 292                     addr > sizeof(struct user) - 7)
 293                         break;
 294
 295                 switch (addr) {
 296                 case 0 ... sizeof(struct user_regs_struct):
 297                         ret = putreg(child, addr, data);
 298                         break;
 299                 /* Disallows to set a breakpoint into the vsyscall */
 300                 case offsetof(struct user, u_debugreg[0]):
 301                         if (data >= TASK_SIZE-7) break;
 302                         child->thread.debugreg0 = data;
 303                         ret = 0;
 304                         break;
 305                 case offsetof(struct user, u_debugreg[1]):
 306                         if (data >= TASK_SIZE-7) break;
 307                         child->thread.debugreg1 = data;
 308                         ret = 0;
 309                         break;
 310                 case offsetof(struct user, u_debugreg[2]):
 311                         if (data >= TASK_SIZE-7) break;
 312                         child->thread.debugreg2 = data;
 313                         ret = 0;
 314                         break;
 315                 case offsetof(struct user, u_debugreg[3]):
 316                         if (data >= TASK_SIZE-7) break;
 317                         child->thread.debugreg3 = data;
 318                         ret = 0;
 319                         break;
 320                 case offsetof(struct user, u_debugreg[6]):
 321                                   if (data >> 32)
 322                                 break;
 323                         child->thread.debugreg6 = data;
 324                         ret = 0;
 325                         break;
 326                 case offsetof(struct user, u_debugreg[7]):
 327                         /* See arch/i386/kernel/ptrace.c for an explanation of
 328                          * this awkward check.*/
 329                                   data &= ~DR_CONTROL_RESERVED;
 330                                   for(i=0; i<4; i++)
 331                                           if ((0x5454 >> ((data >> (16 + 4*i)) & 0xf)) & 1)
 332                                         break;
 333                         if (i == 4) {
 334                                 child->thread.debugreg7 = data;
 335                           ret = 0;
 336                   }
 337                   break;
 338                 }
 339                 break;
 340         case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
 341         case PTRACE_CONT: { /* restart after signal. */
 342                 long tmp;
 343
 344                 ret = -EIO;
 345                 if ((unsigned long) data > _NSIG)
 346                         break;
 347                 if (request == PTRACE_SYSCALL)
 348                         set_tsk_thread_flag(child,TIF_SYSCALL_TRACE);
 349                 else
 350                         clear_tsk_thread_flag(child,TIF_SYSCALL_TRACE);
 351                 clear_tsk_thread_flag(child, TIF_SINGLESTEP);
 352                 child->exit_code = data;
 353         /* make sure the single step bit is not set. */
 354                 tmp = get_stack_long(child, EFL_OFFSET);
 355                 tmp &= ~TRAP_FLAG;
 356                 put_stack_long(child, EFL_OFFSET,tmp);
 357                 wake_up_process(child);
 358                 ret = 0;
 359                 break;
 360         }
 361
 362 #ifdef CONFIG_IA32_EMULATION
 363                 /* This makes only sense with 32bit programs. Allow a
 364                    64bit debugger to fully examine them too. Better
 365                    don't use it against 64bit processes, use
 366                    PTRACE_ARCH_PRCTL instead. */
 367         case PTRACE_SET_THREAD_AREA: {
 368                 struct user_desc __user *p;
 369                 int old;
 370                 p = (struct user_desc __user *)data;
 371                 get_user(old,  &p->entry_number);
 372                 put_user(addr, &p->entry_number);
 373                 ret = do_set_thread_area(&child->thread, p);
 374                 put_user(old,  &p->entry_number);
 375                 break;
 376         case PTRACE_GET_THREAD_AREA:
 377                 p = (struct user_desc __user *)data;
 378                 get_user(old,  &p->entry_number);
 379                 put_user(addr, &p->entry_number);
 380                 ret = do_get_thread_area(&child->thread, p);
 381                 put_user(old,  &p->entry_number);
 382                 break;
 383         }
 384 #endif
 385                 /* normal 64bit interface to access TLS data.
 386                    Works just like arch_prctl, except that the arguments
 387                    are reversed. */
 388         case PTRACE_ARCH_PRCTL:
 389                 ret = do_arch_prctl(child, data, addr);
 390                 break;
 391
 392 /*
 393  * make the child exit.  Best I can do is send it a sigkill.
 394  * perhaps it should be put in the status that it wants to
 395  * exit.
 396  */
 397         case PTRACE_KILL: {
 398                 long tmp;
 399
 400                 ret = 0;
 401                 if (child->exit_state == EXIT_ZOMBIE)   /* already dead */
 402                         break;
 403                 clear_tsk_thread_flag(child, TIF_SINGLESTEP);
 404                 child->exit_code = SIGKILL;
 405                 /* make sure the single step bit is not set. */
 406                 tmp = get_stack_long(child, EFL_OFFSET) & ~TRAP_FLAG;
 407                 put_stack_long(child, EFL_OFFSET, tmp);
 408                 wake_up_process(child);
 409                 break;
 410         }
 411
 412         case PTRACE_SINGLESTEP: {  /* set the trap flag. */
 413                 long tmp;
 414
 415                 ret = -EIO;
 416                 if ((unsigned long) data > _NSIG)
 417                         break;
 418                 clear_tsk_thread_flag(child,TIF_SYSCALL_TRACE);
 419                 if ((child->ptrace & PT_DTRACE) == 0) {
 420                         /* Spurious delayed TF traps may occur */
 421                         child->ptrace |= PT_DTRACE;
 422                 }
 423                 tmp = get_stack_long(child, EFL_OFFSET) | TRAP_FLAG;
 424                 put_stack_long(child, EFL_OFFSET, tmp);
 425                 set_tsk_thread_flag(child, TIF_SINGLESTEP);
 426                 child->exit_code = data;
 427                 /* give it a chance to run. */
 428                 wake_up_process(child);
 429                 ret = 0;
 430                 break;
 431         }
 432
 433         case PTRACE_DETACH:
 434                 /* detach a process that was attached. */
 435                 ret = ptrace_detach(child, data);
 436                 break;
 437
 438         case PTRACE_GETREGS: { /* Get all gp regs from the child. */
 439                 if (!access_ok(VERIFY_WRITE, (unsigned __user *)data,
 440                                sizeof(struct user_regs_struct))) {
 441                         ret = -EIO;
 442                         break;
 443                 }
 444                 ret = 0;
 445                 for (ui = 0; ui < sizeof(struct user_regs_struct); ui += sizeof(long)) {
 446                         ret |= __put_user(getreg(child, ui),(unsigned long __user *) data);
 447                         data += sizeof(long);
 448                 }
 449                 break;
 450         }
 451
 452         case PTRACE_SETREGS: { /* Set all gp regs in the child. */
 453                 unsigned long tmp;
 454                 if (!access_ok(VERIFY_READ, (unsigned __user *)data,
 455                                sizeof(struct user_regs_struct))) {
 456                         ret = -EIO;
 457                         break;
 458                 }
 459                 ret = 0;
 460                 for (ui = 0; ui < sizeof(struct user_regs_struct); ui += sizeof(long)) {
 461                         ret |= __get_user(tmp, (unsigned long __user *) data);
 462                         putreg(child, ui, tmp);
 463                         data += sizeof(long);
 464                 }
 465                 break;
 466         }
 467
 468         case PTRACE_GETFPREGS: { /* Get the child extended FPU state. */
 469                 if (!access_ok(VERIFY_WRITE, (unsigned __user *)data,
 470                                sizeof(struct user_i387_struct))) {
 471                         ret = -EIO;
 472                         break;
 473                 }
 474                 ret = get_fpregs((struct user_i387_struct __user *)data, child);
 475                 break;
 476         }
 477
 478         case PTRACE_SETFPREGS: { /* Set the child extended FPU state. */
 479                 if (!access_ok(VERIFY_READ, (unsigned __user *)data,
 480                                sizeof(struct user_i387_struct))) {
 481                         ret = -EIO;
 482                         break;
 483                 }
 484                 set_stopped_child_used_math(child);
 485                 ret = set_fpregs(child, (struct user_i387_struct __user *)data);
 486                 break;
 487         }
 488
 489         default:
 490                 ret = ptrace_request(child, request, addr, data);
 491                 break;
 492         }
 493 out_tsk:
 494         put_task_struct(child);
 495 out:
 496         unlock_kernel();
 497         return ret;
 498 }
 499
 500 static void syscall_trace(struct pt_regs *regs)
 501 {
 502
 503 #if 0
 504         printk("trace %s rip %lx rsp %lx rax %d origrax %d caller %lx tiflags %x ptrace %x\n",
 505                current->comm,
 506                regs->rip, regs->rsp, regs->rax, regs->orig_rax, __builtin_return_address(0),
 507                current_thread_info()->flags, current->ptrace);
 508 #endif
 509
 510         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 511                                 ? 0x80 : 0));
 512         /*
 513          * this isn't the same as continuing with a signal, but it will do
 514          * for normal use.  strace only continues with a signal if the
 515          * stopping signal is not SIGTRAP.  -brl
 516          */
 517         if (current->exit_code) {
 518                 send_sig(current->exit_code, current, 1);
 519                 current->exit_code = 0;
 520         }
 521 }
 522
 523 asmlinkage void syscall_trace_enter(struct pt_regs *regs)
 524 {
 525         /* do the secure computing check first */
 526         secure_computing(regs->orig_rax);
 527
 528         if (unlikely(current->audit_context))
 529                 audit_syscall_entry(current, regs->orig_rax,
 530                                     regs->rdi, regs->rsi,
 531                                     regs->rdx, regs->r10);
 532
 533         if (test_thread_flag(TIF_SYSCALL_TRACE)
 534             && (current->ptrace & PT_PTRACED))
 535                 syscall_trace(regs);
 536 }
 537
 538 asmlinkage void syscall_trace_leave(struct pt_regs *regs)
 539 {
 540         if (unlikely(current->audit_context))
 541                 audit_syscall_exit(current, regs->rax);
 542
 543         if ((test_thread_flag(TIF_SYSCALL_TRACE)
 544              || test_thread_flag(TIF_SINGLESTEP))
 545             && (current->ptrace & PT_PTRACED))
 546                 syscall_trace(regs);
 547 }