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
  19 #include <asm/uaccess.h>
  20 #include <asm/pgtable.h>
  21 #include <asm/system.h>
  22 #include <asm/processor.h>
  23 #include <asm/i387.h>
  24 #include <asm/debugreg.h>
  25
  26 /*
  27  * does not yet catch signals sent when the child dies.
  28  * in exit.c or in signal.c.
  29  */
  30
  31 /* determines which flags the user has access to. */
  32 /* 1 = access 0 = no access */
  33 #define FLAG_MASK 0x44dd5UL
  34
  35 /* set's the trap flag. */
  36 #define TRAP_FLAG 0x100UL
  37
  38 /*
  39  * eflags and offset of eflags on child stack..
  40  */
  41 #define EFLAGS offsetof(struct pt_regs, eflags)
  42 #define EFL_OFFSET ((int)(EFLAGS-sizeof(struct pt_regs)))
  43
  44 /*
  45  * this routine will get a word off of the processes privileged stack.
  46  * the offset is how far from the base addr as stored in the TSS.
  47  * this routine assumes that all the privileged stacks are in our
  48  * data space.
  49  */
  50 static inline unsigned long get_stack_long(struct task_struct *task, int offset)
  51 {
  52         unsigned char *stack;
  53
  54         stack = (unsigned char *)task->thread.rsp0;
  55         stack += offset;
  56         return (*((unsigned long *)stack));
  57 }
  58
  59 /*
  60  * this routine will put a word on the processes privileged stack.
  61  * the offset is how far from the base addr as stored in the TSS.
  62  * this routine assumes that all the privileged stacks are in our
  63  * data space.
  64  */
  65 static inline long put_stack_long(struct task_struct *task, int offset,
  66         unsigned long data)
  67 {
  68         unsigned char * stack;
  69
  70         stack = (unsigned char *) task->thread.rsp0;
  71         stack += offset;
  72         *(unsigned long *) stack = data;
  73         return 0;
  74 }
  75
  76 /*
  77  * Called by kernel/ptrace.c when detaching..
  78  *
  79  * Make sure the single step bit is not set.
  80  */
  81 void ptrace_disable(struct task_struct *child)
  82 {
  83         long tmp;
  84
  85         tmp = get_stack_long(child, EFL_OFFSET) & ~TRAP_FLAG;
  86         put_stack_long(child, EFL_OFFSET, tmp);
  87 }
  88
  89 static int putreg(struct task_struct *child,
  90         unsigned long regno, unsigned long value)
  91 {
  92         unsigned long tmp;
  93         if (child->thread.flags & THREAD_IA32)
  94                 value &= 0xffffffff;
  95         switch (regno) {
  96                 case offsetof(struct user_regs_struct,fs):
  97                         if (value && (value & 3) != 3)
  98                                 return -EIO;
  99                         child->thread.fsindex = value & 0xffff;
 100                         return 0;
 101                 case offsetof(struct user_regs_struct,gs):
 102                         if (value && (value & 3) != 3)
 103                                 return -EIO;
 104                         child->thread.gsindex = value & 0xffff;
 105                         return 0;
 106                 case offsetof(struct user_regs_struct,ds):
 107                         if (value && (value & 3) != 3)
 108                                 return -EIO;
 109                         child->thread.ds = value & 0xffff;
 110                         return 0;
 111                 case offsetof(struct user_regs_struct,es):
 112                         if (value && (value & 3) != 3)
 113                                 return -EIO;
 114                         child->thread.es = value & 0xffff;
 115                         return 0;
 116                 case offsetof(struct user_regs_struct,fs_base):
 117                         if (value >= TASK_SIZE)
 118                                 return -EIO;
 119                         child->thread.fs = value;
 120                         return 0;
 121                 case offsetof(struct user_regs_struct,gs_base):
 122                         if (value >= TASK_SIZE)
 123                                 return -EIO;
 124                         child->thread.gs = value;
 125                         return 0;
 126                 case offsetof(struct user_regs_struct, eflags):
 127                         value &= FLAG_MASK;
 128                         tmp = get_stack_long(child, EFL_OFFSET);
 129                         tmp &= ~FLAG_MASK;
 130                         value |= tmp;
 131                         break;
 132                 case offsetof(struct user_regs_struct,cs):
 133                         if ((value & 3) != 3)
 134                                 return -EIO;
 135                         value &= 0xffff;
 136                         break;
 137                 case offsetof(struct user_regs_struct,ss):
 138                         if ((value & 3) != 3)
 139                                 return -EIO;
 140                         value &= 0xffff;
 141             break;
 142                 case offsetof(struct user_regs_struct, rip):
 143                         /* Check if the new RIP address is canonical */
 144                         if (value >= TASK_SIZE)
 145                                 return -EIO;
 146                         break;
 147         }
 148         put_stack_long(child, regno - sizeof(struct pt_regs), value);
 149         return 0;
 150 }
 151
 152 static unsigned long getreg(struct task_struct *child, unsigned long regno)
 153 {
 154         unsigned long val;
 155         switch (regno) {
 156                 case offsetof(struct user_regs_struct, fs):
 157                         return child->thread.fsindex;
 158                 case offsetof(struct user_regs_struct, gs):
 159                         return child->thread.gsindex;
 160                 case offsetof(struct user_regs_struct, ds):
 161                         return child->thread.ds;
 162                 case offsetof(struct user_regs_struct, es):
 163                         return child->thread.es;
 164                 case offsetof(struct user_regs_struct, fs_base):
 165                         return child->thread.fs;
 166                 case offsetof(struct user_regs_struct, gs_base):
 167                         return child->thread.gs;
 168                 default:
 169                         regno = regno - sizeof(struct pt_regs);
 170                         val = get_stack_long(child, regno);
 171                         if (child->thread.flags & THREAD_IA32)
 172                                 val &= 0xffffffff;
 173                         return val;
 174         }
 175
 176 }
 177
 178 asmlinkage long sys_ptrace(long request, long pid, long addr, long data)
 179 {
 180         struct task_struct *child;
 181         struct user * dummy = NULL;
 182         long i, ret;
 183
 184         /* This lock_kernel fixes a subtle race with suid exec */
 185         lock_kernel();
 186         ret = -EPERM;
 187         if (request == PTRACE_TRACEME) {
 188                 /* are we already being traced? */
 189                 if (current->ptrace & PT_PTRACED)
 190                         goto out;
 191                 /* set the ptrace bit in the process flags. */
 192                 current->ptrace |= PT_PTRACED;
 193                 ret = 0;
 194                 goto out;
 195         }
 196         ret = -ESRCH;
 197         read_lock(&tasklist_lock);
 198         child = find_task_by_pid(pid);
 199         if (child)
 200                 get_task_struct(child);
 201         read_unlock(&tasklist_lock);
 202         if (!child)
 203                 goto out;
 204
 205         ret = -EPERM;
 206         if (pid == 1)           /* you may not mess with init */
 207                 goto out_tsk;
 208
 209         if (request == PTRACE_ATTACH) {
 210                 ret = ptrace_attach(child);
 211                 goto out_tsk;
 212         }
 213         ret = ptrace_check_attach(child, request == PTRACE_KILL);
 214         if (ret < 0)
 215                 goto out_tsk;
 216
 217         switch (request) {
 218         /* when I and D space are separate, these will need to be fixed. */
 219         case PTRACE_PEEKTEXT: /* read word at location addr. */
 220         case PTRACE_PEEKDATA: {
 221                 unsigned long tmp;
 222                 int copied;
 223
 224                 copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
 225                 ret = -EIO;
 226                 if (copied != sizeof(tmp))
 227                         break;
 228                 ret = put_user(tmp,(unsigned long *) data);
 229                 break;
 230         }
 231
 232         /* read the word at location addr in the USER area. */
 233         case PTRACE_PEEKUSR: {
 234                 unsigned long tmp;
 235
 236                 ret = -EIO;
 237                 if ((addr & 7) || addr < 0 ||
 238                     addr > sizeof(struct user) - 7)
 239                         break;
 240
 241                 tmp = 0;  /* Default return condition */
 242                 if(addr < sizeof(struct user_regs_struct))
 243                         tmp = getreg(child, addr);
 244                 if(addr >= (long) &dummy->u_debugreg[0] &&
 245                    addr <= (long) &dummy->u_debugreg[7]){
 246                         addr -= (long) &dummy->u_debugreg[0];
 247                         addr = addr >> 3;
 248                         tmp = child->thread.debugreg[addr];
 249                 }
 250                 ret = put_user(tmp,(unsigned long *) data);
 251                 break;
 252         }
 253
 254         /* when I and D space are separate, this will have to be fixed. */
 255         case PTRACE_POKETEXT: /* write the word at location addr. */
 256         case PTRACE_POKEDATA:
 257                 ret = 0;
 258                 if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data))
 259                         break;
 260                 ret = -EIO;
 261                 break;
 262
 263         case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
 264                 ret = -EIO;
 265                 if ((addr & 7) || addr < 0 ||
 266                     addr > sizeof(struct user) - 7)
 267                         break;
 268
 269                 if (addr < sizeof(struct user_regs_struct)) {
 270                         ret = putreg(child, addr, data);
 271                         break;
 272                 }
 273                 /* We need to be very careful here.  We implicitly
 274                    want to modify a portion of the task_struct, and we
 275                    have to be selective about what portions we allow someone
 276                    to modify. */
 277
 278                   ret = -EIO;
 279                   if(addr >= (long) &dummy->u_debugreg[0] &&
 280                      addr <= (long) &dummy->u_debugreg[7]){
 281
 282                           if(addr == (long) &dummy->u_debugreg[4]) break;
 283                           if(addr == (long) &dummy->u_debugreg[5]) break;
 284                           if(addr < (long) &dummy->u_debugreg[4] &&
 285                              ((unsigned long) data) >= TASK_SIZE-3) break;
 286
 287                           if (addr == (long) &dummy->u_debugreg[6]) {
 288                                   if (data >> 32)
 289                                           goto out_tsk;
 290                           }
 291
 292                           if(addr == (long) &dummy->u_debugreg[7]) {
 293                                   data &= ~DR_CONTROL_RESERVED;
 294                                   for(i=0; i<4; i++)
 295                                           if ((0x5454 >> ((data >> (16 + 4*i)) & 0xf)) & 1)
 296                                                   goto out_tsk;
 297                           }
 298
 299                           addr -= (long) &dummy->u_debugreg;
 300                           addr = addr >> 3;
 301                           child->thread.debugreg[addr] = data;
 302                           ret = 0;
 303                   }
 304                   break;
 305
 306         case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
 307         case PTRACE_CONT: { /* restart after signal. */
 308                 long tmp;
 309
 310                 ret = -EIO;
 311                 if ((unsigned long) data > _NSIG)
 312                         break;
 313                 if (request == PTRACE_SYSCALL)
 314                         child->ptrace |= PT_TRACESYS;
 315                 else
 316                         child->ptrace &= ~PT_TRACESYS;
 317                 child->exit_code = data;
 318         /* make sure the single step bit is not set. */
 319                 tmp = get_stack_long(child, EFL_OFFSET);
 320                 tmp &= ~TRAP_FLAG;
 321                 put_stack_long(child, EFL_OFFSET,tmp);
 322                 wake_up_process(child);
 323                 ret = 0;
 324                 break;
 325         }
 326
 327 /*
 328  * make the child exit.  Best I can do is send it a sigkill.
 329  * perhaps it should be put in the status that it wants to
 330  * exit.
 331  */
 332         case PTRACE_KILL: {
 333                 long tmp;
 334
 335                 ret = 0;
 336                 if (child->state == TASK_ZOMBIE)        /* already dead */
 337                         break;
 338                 child->exit_code = SIGKILL;
 339                 /* make sure the single step bit is not set. */
 340                 tmp = get_stack_long(child, EFL_OFFSET) & ~TRAP_FLAG;
 341                 put_stack_long(child, EFL_OFFSET, tmp);
 342                 wake_up_process(child);
 343                 break;
 344         }
 345
 346         case PTRACE_SINGLESTEP: {  /* set the trap flag. */
 347                 long tmp;
 348
 349                 ret = -EIO;
 350                 if ((unsigned long) data > _NSIG)
 351                         break;
 352                 child->ptrace &= ~PT_TRACESYS;
 353                 if ((child->ptrace & PT_DTRACE) == 0) {
 354                         /* Spurious delayed TF traps may occur */
 355                         child->ptrace |= PT_DTRACE;
 356                 }
 357                 tmp = get_stack_long(child, EFL_OFFSET) | TRAP_FLAG;
 358                 put_stack_long(child, EFL_OFFSET, tmp);
 359                 child->exit_code = data;
 360                 /* give it a chance to run. */
 361                 wake_up_process(child);
 362                 ret = 0;
 363                 break;
 364         }
 365
 366         case PTRACE_DETACH:
 367                 /* detach a process that was attached. */
 368                 ret = ptrace_detach(child, data);
 369                 break;
 370
 371         case PTRACE_GETREGS: { /* Get all gp regs from the child. */
 372                 if (!access_ok(VERIFY_WRITE, (unsigned *)data, FRAME_SIZE)) {
 373                         ret = -EIO;
 374                         break;
 375                 }
 376                 for ( i = 0; i < sizeof(struct user_regs_struct); i += sizeof(long) ) {
 377                         __put_user(getreg(child, i),(unsigned long *) data);
 378                         data += sizeof(long);
 379                 }
 380                 ret = 0;
 381                 break;
 382         }
 383
 384         case PTRACE_SETREGS: { /* Set all gp regs in the child. */
 385                 unsigned long tmp;
 386                 if (!access_ok(VERIFY_READ, (unsigned *)data, FRAME_SIZE)) {
 387                         ret = -EIO;
 388                         break;
 389                 }
 390                 for ( i = 0; i < sizeof(struct user_regs_struct); i += sizeof(long) ) {
 391                         __get_user(tmp, (unsigned long *) data);
 392                         putreg(child, i, tmp);
 393                         data += sizeof(long);
 394                 }
 395                 ret = 0;
 396                 break;
 397         }
 398
 399         case PTRACE_GETFPREGS: { /* Get the child extended FPU state. */
 400                 if (!access_ok(VERIFY_WRITE, (unsigned *)data,
 401                                sizeof(struct user_i387_struct))) {
 402                         ret = -EIO;
 403                         break;
 404                 }
 405                 ret = get_fpregs((struct user_i387_struct *)data, child);
 406                 break;
 407         }
 408
 409         case PTRACE_SETFPREGS: { /* Set the child extended FPU state. */
 410                 if (!access_ok(VERIFY_READ, (unsigned *)data,
 411                                sizeof(struct user_i387_struct))) {
 412                         ret = -EIO;
 413                         break;
 414                 }
 415                 unlazy_fpu(child);
 416                 ret = set_fpregs(child, (struct user_i387_struct *)data);
 417                 if (!ret)
 418                         child->used_math = 1;
 419                 break;
 420         }
 421
 422         case PTRACE_SETOPTIONS: {
 423                 if (data & PTRACE_O_TRACESYSGOOD)
 424                         child->ptrace |= PT_TRACESYSGOOD;
 425                 else
 426                         child->ptrace &= ~PT_TRACESYSGOOD;
 427                 ret = 0;
 428                 break;
 429         }
 430
 431         default:
 432                 ret = -EIO;
 433                 break;
 434         }
 435 out_tsk:
 436         free_task_struct(child);
 437 out:
 438         unlock_kernel();
 439         return ret;
 440 }
 441
 442 asmlinkage void syscall_trace(struct pt_regs *regs)
 443 {
 444         if ((current->ptrace & (PT_PTRACED|PT_TRACESYS)) !=
 445                         (PT_PTRACED|PT_TRACESYS))
 446                 return;
 447
 448         current->exit_code = SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
 449                                         ? 0x80 : 0);
 450         current->state = TASK_STOPPED;
 451         notify_parent(current, SIGCHLD);
 452         schedule();
 453         /*
 454          * this isn't the same as continuing with a signal, but it will do
 455          * for normal use.  strace only continues with a signal if the
 456          * stopping signal is not SIGTRAP.  -brl
 457          */
 458         if (current->exit_code) {
 459                 send_sig(current->exit_code, current, 1);
 460                 current->exit_code = 0;
 461         }
 462 }