arch/x86/kernel/ptrace_64.c

   1 /* By Ross Biro 1/23/92 */
   2 /*
   3  * Pentium III FXSR, SSE support
   4  *      Gareth Hughes <gareth@valinux.com>, May 2000
   5  *
   6  * x86-64 port 2000-2002 Andi Kleen
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/sched.h>
  11 #include <linux/mm.h>
  12 #include <linux/smp.h>
  13 #include <linux/errno.h>
  14 #include <linux/ptrace.h>
  15 #include <linux/user.h>
  16 #include <linux/security.h>
  17 #include <linux/audit.h>
  18 #include <linux/seccomp.h>
  19 #include <linux/signal.h>
  20
  21 #include <asm/uaccess.h>
  22 #include <asm/pgtable.h>
  23 #include <asm/system.h>
  24 #include <asm/processor.h>
  25 #include <asm/prctl.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 /*
  39  * Determines which flags the user has access to [1 = access, 0 = no access].
  40  * Prohibits changing ID(21), VIP(20), VIF(19), VM(17), IOPL(12-13), IF(9).
  41  * Also masks reserved bits (63-22, 15, 5, 3, 1).
  42  */
  43 #define FLAG_MASK 0x54dd5UL
  44
  45 /*
  46  * Called by kernel/ptrace.c when detaching..
  47  *
  48  * Make sure the single step bit is not set.
  49  */
  50 void ptrace_disable(struct task_struct *child)
  51 {
  52         user_disable_single_step(child);
  53 }
  54
  55 static unsigned long *pt_regs_access(struct pt_regs *regs, unsigned long offset)
  56 {
  57         BUILD_BUG_ON(offsetof(struct pt_regs, r15) != 0);
  58         return &regs->r15 + (offset / sizeof(regs->r15));
  59 }
  60
  61 static int putreg(struct task_struct *child,
  62         unsigned long regno, unsigned long value)
  63 {
  64         struct pt_regs *regs = task_pt_regs(child);
  65         switch (regno) {
  66                 case offsetof(struct user_regs_struct,fs):
  67                         if (value && (value & 3) != 3)
  68                                 return -EIO;
  69                         child->thread.fsindex = value & 0xffff;
  70                         return 0;
  71                 case offsetof(struct user_regs_struct,gs):
  72                         if (value && (value & 3) != 3)
  73                                 return -EIO;
  74                         child->thread.gsindex = value & 0xffff;
  75                         return 0;
  76                 case offsetof(struct user_regs_struct,ds):
  77                         if (value && (value & 3) != 3)
  78                                 return -EIO;
  79                         child->thread.ds = value & 0xffff;
  80                         return 0;
  81                 case offsetof(struct user_regs_struct,es):
  82                         if (value && (value & 3) != 3)
  83                                 return -EIO;
  84                         child->thread.es = value & 0xffff;
  85                         return 0;
  86                 case offsetof(struct user_regs_struct,ss):
  87                         if ((value & 3) != 3)
  88                                 return -EIO;
  89                         value &= 0xffff;
  90                         return 0;
  91                 case offsetof(struct user_regs_struct,fs_base):
  92                         if (value >= TASK_SIZE_OF(child))
  93                                 return -EIO;
  94                         /*
  95                          * When changing the segment base, use do_arch_prctl
  96                          * to set either thread.fs or thread.fsindex and the
  97                          * corresponding GDT slot.
  98                          */
  99                         if (child->thread.fs != value)
 100                                 return do_arch_prctl(child, ARCH_SET_FS, value);
 101                         return 0;
 102                 case offsetof(struct user_regs_struct,gs_base):
 103                         /*
 104                          * Exactly the same here as the %fs handling above.
 105                          */
 106                         if (value >= TASK_SIZE_OF(child))
 107                                 return -EIO;
 108                         if (child->thread.gs != value)
 109                                 return do_arch_prctl(child, ARCH_SET_GS, value);
 110                         return 0;
 111                 case offsetof(struct user_regs_struct,flags):
 112                         value &= FLAG_MASK;
 113                         /*
 114                          * If the user value contains TF, mark that
 115                          * it was not "us" (the debugger) that set it.
 116                          * If not, make sure it stays set if we had.
 117                          */
 118                         if (value & X86_EFLAGS_TF)
 119                                 clear_tsk_thread_flag(child, TIF_FORCED_TF);
 120                         else if (test_tsk_thread_flag(child, TIF_FORCED_TF))
 121                                 value |= X86_EFLAGS_TF;
 122                         value |= regs->flags & ~FLAG_MASK;
 123                         break;
 124                 case offsetof(struct user_regs_struct,cs):
 125                         if ((value & 3) != 3)
 126                                 return -EIO;
 127                         value &= 0xffff;
 128                         break;
 129         }
 130         *pt_regs_access(regs, regno) = value;
 131         return 0;
 132 }
 133
 134 static unsigned long getreg(struct task_struct *child, unsigned long regno)
 135 {
 136         struct pt_regs *regs = task_pt_regs(child);
 137         unsigned long val;
 138         switch (regno) {
 139                 case offsetof(struct user_regs_struct, fs):
 140                         return child->thread.fsindex;
 141                 case offsetof(struct user_regs_struct, gs):
 142                         return child->thread.gsindex;
 143                 case offsetof(struct user_regs_struct, ds):
 144                         return child->thread.ds;
 145                 case offsetof(struct user_regs_struct, es):
 146                         return child->thread.es;
 147                 case offsetof(struct user_regs_struct, fs_base):
 148                         /*
 149                          * do_arch_prctl may have used a GDT slot instead of
 150                          * the MSR.  To userland, it appears the same either
 151                          * way, except the %fs segment selector might not be 0.
 152                          */
 153                         if (child->thread.fs != 0)
 154                                 return child->thread.fs;
 155                         if (child->thread.fsindex != FS_TLS_SEL)
 156                                 return 0;
 157                         return get_desc_base(&child->thread.tls_array[FS_TLS]);
 158                 case offsetof(struct user_regs_struct, gs_base):
 159                         /*
 160                          * Exactly the same here as the %fs handling above.
 161                          */
 162                         if (child->thread.gs != 0)
 163                                 return child->thread.gs;
 164                         if (child->thread.gsindex != GS_TLS_SEL)
 165                                 return 0;
 166                         return get_desc_base(&child->thread.tls_array[GS_TLS]);
 167                 case offsetof(struct user_regs_struct, flags):
 168                         /*
 169                          * If the debugger set TF, hide it from the readout.
 170                          */
 171                         val = regs->flags;
 172                         if (test_tsk_thread_flag(child, TIF_IA32))
 173                                 val &= 0xffffffff;
 174                         if (test_tsk_thread_flag(child, TIF_FORCED_TF))
 175                                 val &= ~X86_EFLAGS_TF;
 176                         return val;
 177                 default:
 178                         val = *pt_regs_access(regs, regno);
 179                         if (test_tsk_thread_flag(child, TIF_IA32))
 180                                 val &= 0xffffffff;
 181                         return val;
 182         }
 183
 184 }
 185
 186 unsigned long ptrace_get_debugreg(struct task_struct *child, int n)
 187 {
 188         switch (n) {
 189         case 0:         return child->thread.debugreg0;
 190         case 1:         return child->thread.debugreg1;
 191         case 2:         return child->thread.debugreg2;
 192         case 3:         return child->thread.debugreg3;
 193         case 6:         return child->thread.debugreg6;
 194         case 7:         return child->thread.debugreg7;
 195         }
 196         return 0;
 197 }
 198
 199 int ptrace_set_debugreg(struct task_struct *child, int n, unsigned long data)
 200 {
 201         int i;
 202
 203         if (n < 4) {
 204                 int dsize = test_tsk_thread_flag(child, TIF_IA32) ? 3 : 7;
 205                 if (unlikely(data >= TASK_SIZE_OF(child) - dsize))
 206                         return -EIO;
 207         }
 208
 209         switch (n) {
 210         case 0:         child->thread.debugreg0 = data; break;
 211         case 1:         child->thread.debugreg1 = data; break;
 212         case 2:         child->thread.debugreg2 = data; break;
 213         case 3:         child->thread.debugreg3 = data; break;
 214
 215         case 6:
 216                 if (data >> 32)
 217                         return -EIO;
 218                 child->thread.debugreg6 = data;
 219                 break;
 220
 221         case 7:
 222                 /*
 223                  * See ptrace_32.c for an explanation of this awkward check.
 224                  */
 225                 data &= ~DR_CONTROL_RESERVED;
 226                 for (i = 0; i < 4; i++)
 227                         if ((0x5554 >> ((data >> (16 + 4*i)) & 0xf)) & 1)
 228                                 return -EIO;
 229                 child->thread.debugreg7 = data;
 230                 if (data)
 231                         set_tsk_thread_flag(child, TIF_DEBUG);
 232                 else
 233                         clear_tsk_thread_flag(child, TIF_DEBUG);
 234                 break;
 235         }
 236
 237         return 0;
 238 }
 239
 240 long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 241 {
 242         long ret;
 243         unsigned ui;
 244
 245         switch (request) {
 246         /* when I and D space are separate, these will need to be fixed. */
 247         case PTRACE_PEEKTEXT: /* read word at location addr. */
 248         case PTRACE_PEEKDATA:
 249                 ret = generic_ptrace_peekdata(child, addr, data);
 250                 break;
 251
 252         /* read the word at location addr in the USER area. */
 253         case PTRACE_PEEKUSR: {
 254                 unsigned long tmp;
 255
 256                 ret = -EIO;
 257                 if ((addr & 7) ||
 258                     addr > sizeof(struct user) - 7)
 259                         break;
 260
 261                 tmp = 0;
 262                 if (addr < sizeof(struct user_regs_struct))
 263                         tmp = getreg(child, addr);
 264                 else if (addr >= offsetof(struct user, u_debugreg[0])) {
 265                         addr -= offsetof(struct user, u_debugreg[0]);
 266                         tmp = ptrace_get_debugreg(child, addr / sizeof(long));
 267                 }
 268
 269                 ret = put_user(tmp,(unsigned long __user *) data);
 270                 break;
 271         }
 272
 273         /* when I and D space are separate, this will have to be fixed. */
 274         case PTRACE_POKETEXT: /* write the word at location addr. */
 275         case PTRACE_POKEDATA:
 276                 ret = generic_ptrace_pokedata(child, addr, data);
 277                 break;
 278
 279         case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
 280                 ret = -EIO;
 281                 if ((addr & 7) ||
 282                     addr > sizeof(struct user) - 7)
 283                         break;
 284
 285                 if (addr < sizeof(struct user_regs_struct))
 286                         ret = putreg(child, addr, data);
 287                 else if (addr >= offsetof(struct user, u_debugreg[0])) {
 288                         addr -= offsetof(struct user, u_debugreg[0]);
 289                         ret = ptrace_set_debugreg(child,
 290                                                   addr / sizeof(long), data);
 291                 }
 292                 break;
 293
 294 #ifdef CONFIG_IA32_EMULATION
 295                 /* This makes only sense with 32bit programs. Allow a
 296                    64bit debugger to fully examine them too. Better
 297                    don't use it against 64bit processes, use
 298                    PTRACE_ARCH_PRCTL instead. */
 299         case PTRACE_GET_THREAD_AREA:
 300                 if (addr < 0)
 301                         return -EIO;
 302                 ret = do_get_thread_area(child, addr,
 303                                          (struct user_desc __user *) data);
 304
 305                 break;
 306         case PTRACE_SET_THREAD_AREA:
 307                 if (addr < 0)
 308                         return -EIO;
 309                 ret = do_set_thread_area(child, addr,
 310                                          (struct user_desc __user *) data, 0);
 311                 break;
 312 #endif
 313                 /* normal 64bit interface to access TLS data.
 314                    Works just like arch_prctl, except that the arguments
 315                    are reversed. */
 316         case PTRACE_ARCH_PRCTL:
 317                 ret = do_arch_prctl(child, data, addr);
 318                 break;
 319
 320         case PTRACE_GETREGS: { /* Get all gp regs from the child. */
 321                 if (!access_ok(VERIFY_WRITE, (unsigned __user *)data,
 322                                sizeof(struct user_regs_struct))) {
 323                         ret = -EIO;
 324                         break;
 325                 }
 326                 ret = 0;
 327                 for (ui = 0; ui < sizeof(struct user_regs_struct); ui += sizeof(long)) {
 328                         ret |= __put_user(getreg(child, ui),(unsigned long __user *) data);
 329                         data += sizeof(long);
 330                 }
 331                 break;
 332         }
 333
 334         case PTRACE_SETREGS: { /* Set all gp regs in the child. */
 335                 unsigned long tmp;
 336                 if (!access_ok(VERIFY_READ, (unsigned __user *)data,
 337                                sizeof(struct user_regs_struct))) {
 338                         ret = -EIO;
 339                         break;
 340                 }
 341                 ret = 0;
 342                 for (ui = 0; ui < sizeof(struct user_regs_struct); ui += sizeof(long)) {
 343                         ret = __get_user(tmp, (unsigned long __user *) data);
 344                         if (ret)
 345                                 break;
 346                         ret = putreg(child, ui, tmp);
 347                         if (ret)
 348                                 break;
 349                         data += sizeof(long);
 350                 }
 351                 break;
 352         }
 353
 354         case PTRACE_GETFPREGS: { /* Get the child extended FPU state. */
 355                 if (!access_ok(VERIFY_WRITE, (unsigned __user *)data,
 356                                sizeof(struct user_i387_struct))) {
 357                         ret = -EIO;
 358                         break;
 359                 }
 360                 ret = get_fpregs((struct user_i387_struct __user *)data, child);
 361                 break;
 362         }
 363
 364         case PTRACE_SETFPREGS: { /* Set the child extended FPU state. */
 365                 if (!access_ok(VERIFY_READ, (unsigned __user *)data,
 366                                sizeof(struct user_i387_struct))) {
 367                         ret = -EIO;
 368                         break;
 369                 }
 370                 set_stopped_child_used_math(child);
 371                 ret = set_fpregs(child, (struct user_i387_struct __user *)data);
 372                 break;
 373         }
 374
 375         default:
 376                 ret = ptrace_request(child, request, addr, data);
 377                 break;
 378         }
 379         return ret;
 380 }
 381
 382 static void syscall_trace(struct pt_regs *regs)
 383 {
 384
 385 #if 0
 386         printk("trace %s ip %lx sp %lx ax %d origrax %d caller %lx tiflags %x ptrace %x\n",
 387                current->comm,
 388                regs->ip, regs->sp, regs->ax, regs->orig_ax, __builtin_return_address(0),
 389                current_thread_info()->flags, current->ptrace);
 390 #endif
 391
 392         ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 393                                 ? 0x80 : 0));
 394         /*
 395          * this isn't the same as continuing with a signal, but it will do
 396          * for normal use.  strace only continues with a signal if the
 397          * stopping signal is not SIGTRAP.  -brl
 398          */
 399         if (current->exit_code) {
 400                 send_sig(current->exit_code, current, 1);
 401                 current->exit_code = 0;
 402         }
 403 }
 404
 405 asmlinkage void syscall_trace_enter(struct pt_regs *regs)
 406 {
 407         /* do the secure computing check first */
 408         secure_computing(regs->orig_ax);
 409
 410         if (test_thread_flag(TIF_SYSCALL_TRACE)
 411             && (current->ptrace & PT_PTRACED))
 412                 syscall_trace(regs);
 413
 414         if (unlikely(current->audit_context)) {
 415                 if (test_thread_flag(TIF_IA32)) {
 416                         audit_syscall_entry(AUDIT_ARCH_I386,
 417                                             regs->orig_ax,
 418                                             regs->bx, regs->cx,
 419                                             regs->dx, regs->si);
 420                 } else {
 421                         audit_syscall_entry(AUDIT_ARCH_X86_64,
 422                                             regs->orig_ax,
 423                                             regs->di, regs->si,
 424                                             regs->dx, regs->r10);
 425                 }
 426         }
 427 }
 428
 429 asmlinkage void syscall_trace_leave(struct pt_regs *regs)
 430 {
 431         if (unlikely(current->audit_context))
 432                 audit_syscall_exit(AUDITSC_RESULT(regs->ax), regs->ax);
 433
 434         if ((test_thread_flag(TIF_SYSCALL_TRACE)
 435              || test_thread_flag(TIF_SINGLESTEP))
 436             && (current->ptrace & PT_PTRACED))
 437                 syscall_trace(regs);
 438 }