Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * linux/kernel/ptrace.c |
| 3 | * |
| 4 | * (C) Copyright 1999 Linus Torvalds |
| 5 | * |
| 6 | * Common interfaces for "ptrace()" which we do not want |
| 7 | * to continually duplicate across every architecture. |
| 8 | */ |
| 9 | |
| 10 | #include <linux/module.h> |
| 11 | #include <linux/sched.h> |
| 12 | #include <linux/errno.h> |
| 13 | #include <linux/mm.h> |
| 14 | #include <linux/highmem.h> |
| 15 | #include <linux/pagemap.h> |
| 16 | #include <linux/smp_lock.h> |
| 17 | #include <linux/ptrace.h> |
| 18 | #include <linux/security.h> |
Jesper Juhl | 7ed20e1 | 2005-05-01 08:59:14 -0700 | [diff] [blame] | 19 | #include <linux/signal.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 20 | |
| 21 | #include <asm/pgtable.h> |
| 22 | #include <asm/uaccess.h> |
| 23 | |
| 24 | /* |
| 25 | * ptrace a task: make the debugger its new parent and |
| 26 | * move it to the ptrace list. |
| 27 | * |
| 28 | * Must be called with the tasklist lock write-held. |
| 29 | */ |
| 30 | void __ptrace_link(task_t *child, task_t *new_parent) |
| 31 | { |
| 32 | if (!list_empty(&child->ptrace_list)) |
| 33 | BUG(); |
| 34 | if (child->parent == new_parent) |
| 35 | return; |
| 36 | list_add(&child->ptrace_list, &child->parent->ptrace_children); |
| 37 | REMOVE_LINKS(child); |
| 38 | child->parent = new_parent; |
| 39 | SET_LINKS(child); |
| 40 | } |
| 41 | |
| 42 | /* |
| 43 | * Turn a tracing stop into a normal stop now, since with no tracer there |
| 44 | * would be no way to wake it up with SIGCONT or SIGKILL. If there was a |
| 45 | * signal sent that would resume the child, but didn't because it was in |
| 46 | * TASK_TRACED, resume it now. |
| 47 | * Requires that irqs be disabled. |
| 48 | */ |
| 49 | void ptrace_untrace(task_t *child) |
| 50 | { |
| 51 | spin_lock(&child->sighand->siglock); |
| 52 | if (child->state == TASK_TRACED) { |
| 53 | if (child->signal->flags & SIGNAL_STOP_STOPPED) { |
| 54 | child->state = TASK_STOPPED; |
| 55 | } else { |
| 56 | signal_wake_up(child, 1); |
| 57 | } |
| 58 | } |
Andrea Arcangeli | 30e0fca | 2005-10-30 15:02:38 -0800 | [diff] [blame] | 59 | if (child->signal->flags & SIGNAL_GROUP_EXIT) { |
| 60 | sigaddset(&child->pending.signal, SIGKILL); |
| 61 | signal_wake_up(child, 1); |
| 62 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 63 | spin_unlock(&child->sighand->siglock); |
| 64 | } |
| 65 | |
| 66 | /* |
| 67 | * unptrace a task: move it back to its original parent and |
| 68 | * remove it from the ptrace list. |
| 69 | * |
| 70 | * Must be called with the tasklist lock write-held. |
| 71 | */ |
| 72 | void __ptrace_unlink(task_t *child) |
| 73 | { |
| 74 | if (!child->ptrace) |
| 75 | BUG(); |
| 76 | child->ptrace = 0; |
| 77 | if (!list_empty(&child->ptrace_list)) { |
| 78 | list_del_init(&child->ptrace_list); |
| 79 | REMOVE_LINKS(child); |
| 80 | child->parent = child->real_parent; |
| 81 | SET_LINKS(child); |
| 82 | } |
| 83 | |
Andrea Arcangeli | 30e0fca | 2005-10-30 15:02:38 -0800 | [diff] [blame] | 84 | ptrace_untrace(child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 85 | } |
| 86 | |
| 87 | /* |
| 88 | * Check that we have indeed attached to the thing.. |
| 89 | */ |
| 90 | int ptrace_check_attach(struct task_struct *child, int kill) |
| 91 | { |
| 92 | int ret = -ESRCH; |
| 93 | |
| 94 | /* |
| 95 | * We take the read lock around doing both checks to close a |
| 96 | * possible race where someone else was tracing our child and |
| 97 | * detached between these two checks. After this locked check, |
| 98 | * we are sure that this is our traced child and that can only |
| 99 | * be changed by us so it's not changing right after this. |
| 100 | */ |
| 101 | read_lock(&tasklist_lock); |
| 102 | if ((child->ptrace & PT_PTRACED) && child->parent == current && |
| 103 | (!(child->ptrace & PT_ATTACHED) || child->real_parent != current) |
| 104 | && child->signal != NULL) { |
| 105 | ret = 0; |
| 106 | spin_lock_irq(&child->sighand->siglock); |
| 107 | if (child->state == TASK_STOPPED) { |
| 108 | child->state = TASK_TRACED; |
| 109 | } else if (child->state != TASK_TRACED && !kill) { |
| 110 | ret = -ESRCH; |
| 111 | } |
| 112 | spin_unlock_irq(&child->sighand->siglock); |
| 113 | } |
| 114 | read_unlock(&tasklist_lock); |
| 115 | |
| 116 | if (!ret && !kill) { |
| 117 | wait_task_inactive(child); |
| 118 | } |
| 119 | |
| 120 | /* All systems go.. */ |
| 121 | return ret; |
| 122 | } |
| 123 | |
Miklos Szeredi | ab8d11b | 2005-09-06 15:18:24 -0700 | [diff] [blame] | 124 | static int may_attach(struct task_struct *task) |
| 125 | { |
| 126 | if (!task->mm) |
| 127 | return -EPERM; |
| 128 | if (((current->uid != task->euid) || |
| 129 | (current->uid != task->suid) || |
| 130 | (current->uid != task->uid) || |
| 131 | (current->gid != task->egid) || |
| 132 | (current->gid != task->sgid) || |
| 133 | (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE)) |
| 134 | return -EPERM; |
| 135 | smp_rmb(); |
| 136 | if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE)) |
| 137 | return -EPERM; |
| 138 | |
| 139 | return security_ptrace(current, task); |
| 140 | } |
| 141 | |
| 142 | int ptrace_may_attach(struct task_struct *task) |
| 143 | { |
| 144 | int err; |
| 145 | task_lock(task); |
| 146 | err = may_attach(task); |
| 147 | task_unlock(task); |
| 148 | return !err; |
| 149 | } |
| 150 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 151 | int ptrace_attach(struct task_struct *task) |
| 152 | { |
| 153 | int retval; |
| 154 | task_lock(task); |
| 155 | retval = -EPERM; |
| 156 | if (task->pid <= 1) |
| 157 | goto bad; |
Linus Torvalds | 28d838c | 2005-11-09 11:33:07 -0800 | [diff] [blame] | 158 | if (task->tgid == current->tgid) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 159 | goto bad; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 160 | /* the same process cannot be attached many times */ |
| 161 | if (task->ptrace & PT_PTRACED) |
| 162 | goto bad; |
Miklos Szeredi | ab8d11b | 2005-09-06 15:18:24 -0700 | [diff] [blame] | 163 | retval = may_attach(task); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 164 | if (retval) |
| 165 | goto bad; |
| 166 | |
| 167 | /* Go */ |
| 168 | task->ptrace |= PT_PTRACED | ((task->real_parent != current) |
| 169 | ? PT_ATTACHED : 0); |
| 170 | if (capable(CAP_SYS_PTRACE)) |
| 171 | task->ptrace |= PT_PTRACE_CAP; |
| 172 | task_unlock(task); |
| 173 | |
| 174 | write_lock_irq(&tasklist_lock); |
| 175 | __ptrace_link(task, current); |
| 176 | write_unlock_irq(&tasklist_lock); |
| 177 | |
| 178 | force_sig_specific(SIGSTOP, task); |
| 179 | return 0; |
| 180 | |
| 181 | bad: |
| 182 | task_unlock(task); |
| 183 | return retval; |
| 184 | } |
| 185 | |
| 186 | int ptrace_detach(struct task_struct *child, unsigned int data) |
| 187 | { |
Jesper Juhl | 7ed20e1 | 2005-05-01 08:59:14 -0700 | [diff] [blame] | 188 | if (!valid_signal(data)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 189 | return -EIO; |
| 190 | |
| 191 | /* Architecture-specific hardware disable .. */ |
| 192 | ptrace_disable(child); |
| 193 | |
| 194 | /* .. re-parent .. */ |
| 195 | child->exit_code = data; |
| 196 | |
| 197 | write_lock_irq(&tasklist_lock); |
| 198 | __ptrace_unlink(child); |
| 199 | /* .. and wake it up. */ |
| 200 | if (child->exit_state != EXIT_ZOMBIE) |
| 201 | wake_up_process(child); |
| 202 | write_unlock_irq(&tasklist_lock); |
| 203 | |
| 204 | return 0; |
| 205 | } |
| 206 | |
| 207 | /* |
| 208 | * Access another process' address space. |
| 209 | * Source/target buffer must be kernel space, |
| 210 | * Do not walk the page table directly, use get_user_pages |
| 211 | */ |
| 212 | |
| 213 | int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) |
| 214 | { |
| 215 | struct mm_struct *mm; |
| 216 | struct vm_area_struct *vma; |
| 217 | struct page *page; |
| 218 | void *old_buf = buf; |
| 219 | |
| 220 | mm = get_task_mm(tsk); |
| 221 | if (!mm) |
| 222 | return 0; |
| 223 | |
| 224 | down_read(&mm->mmap_sem); |
| 225 | /* ignore errors, just check how much was sucessfully transfered */ |
| 226 | while (len) { |
| 227 | int bytes, ret, offset; |
| 228 | void *maddr; |
| 229 | |
| 230 | ret = get_user_pages(tsk, mm, addr, 1, |
| 231 | write, 1, &page, &vma); |
| 232 | if (ret <= 0) |
| 233 | break; |
| 234 | |
| 235 | bytes = len; |
| 236 | offset = addr & (PAGE_SIZE-1); |
| 237 | if (bytes > PAGE_SIZE-offset) |
| 238 | bytes = PAGE_SIZE-offset; |
| 239 | |
| 240 | maddr = kmap(page); |
| 241 | if (write) { |
| 242 | copy_to_user_page(vma, page, addr, |
| 243 | maddr + offset, buf, bytes); |
David Gibson | 5bd0190 | 2005-11-29 19:34:32 -0800 | [diff] [blame] | 244 | if (!PageCompound(page)) |
| 245 | set_page_dirty_lock(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 246 | } else { |
| 247 | copy_from_user_page(vma, page, addr, |
| 248 | buf, maddr + offset, bytes); |
| 249 | } |
| 250 | kunmap(page); |
| 251 | page_cache_release(page); |
| 252 | len -= bytes; |
| 253 | buf += bytes; |
| 254 | addr += bytes; |
| 255 | } |
| 256 | up_read(&mm->mmap_sem); |
| 257 | mmput(mm); |
| 258 | |
| 259 | return buf - old_buf; |
| 260 | } |
| 261 | |
| 262 | int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len) |
| 263 | { |
| 264 | int copied = 0; |
| 265 | |
| 266 | while (len > 0) { |
| 267 | char buf[128]; |
| 268 | int this_len, retval; |
| 269 | |
| 270 | this_len = (len > sizeof(buf)) ? sizeof(buf) : len; |
| 271 | retval = access_process_vm(tsk, src, buf, this_len, 0); |
| 272 | if (!retval) { |
| 273 | if (copied) |
| 274 | break; |
| 275 | return -EIO; |
| 276 | } |
| 277 | if (copy_to_user(dst, buf, retval)) |
| 278 | return -EFAULT; |
| 279 | copied += retval; |
| 280 | src += retval; |
| 281 | dst += retval; |
| 282 | len -= retval; |
| 283 | } |
| 284 | return copied; |
| 285 | } |
| 286 | |
| 287 | int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len) |
| 288 | { |
| 289 | int copied = 0; |
| 290 | |
| 291 | while (len > 0) { |
| 292 | char buf[128]; |
| 293 | int this_len, retval; |
| 294 | |
| 295 | this_len = (len > sizeof(buf)) ? sizeof(buf) : len; |
| 296 | if (copy_from_user(buf, src, this_len)) |
| 297 | return -EFAULT; |
| 298 | retval = access_process_vm(tsk, dst, buf, this_len, 1); |
| 299 | if (!retval) { |
| 300 | if (copied) |
| 301 | break; |
| 302 | return -EIO; |
| 303 | } |
| 304 | copied += retval; |
| 305 | src += retval; |
| 306 | dst += retval; |
| 307 | len -= retval; |
| 308 | } |
| 309 | return copied; |
| 310 | } |
| 311 | |
| 312 | static int ptrace_setoptions(struct task_struct *child, long data) |
| 313 | { |
| 314 | child->ptrace &= ~PT_TRACE_MASK; |
| 315 | |
| 316 | if (data & PTRACE_O_TRACESYSGOOD) |
| 317 | child->ptrace |= PT_TRACESYSGOOD; |
| 318 | |
| 319 | if (data & PTRACE_O_TRACEFORK) |
| 320 | child->ptrace |= PT_TRACE_FORK; |
| 321 | |
| 322 | if (data & PTRACE_O_TRACEVFORK) |
| 323 | child->ptrace |= PT_TRACE_VFORK; |
| 324 | |
| 325 | if (data & PTRACE_O_TRACECLONE) |
| 326 | child->ptrace |= PT_TRACE_CLONE; |
| 327 | |
| 328 | if (data & PTRACE_O_TRACEEXEC) |
| 329 | child->ptrace |= PT_TRACE_EXEC; |
| 330 | |
| 331 | if (data & PTRACE_O_TRACEVFORKDONE) |
| 332 | child->ptrace |= PT_TRACE_VFORK_DONE; |
| 333 | |
| 334 | if (data & PTRACE_O_TRACEEXIT) |
| 335 | child->ptrace |= PT_TRACE_EXIT; |
| 336 | |
| 337 | return (data & ~PTRACE_O_MASK) ? -EINVAL : 0; |
| 338 | } |
| 339 | |
| 340 | static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data) |
| 341 | { |
| 342 | siginfo_t lastinfo; |
| 343 | int error = -ESRCH; |
| 344 | |
| 345 | read_lock(&tasklist_lock); |
| 346 | if (likely(child->sighand != NULL)) { |
| 347 | error = -EINVAL; |
| 348 | spin_lock_irq(&child->sighand->siglock); |
| 349 | if (likely(child->last_siginfo != NULL)) { |
| 350 | lastinfo = *child->last_siginfo; |
| 351 | error = 0; |
| 352 | } |
| 353 | spin_unlock_irq(&child->sighand->siglock); |
| 354 | } |
| 355 | read_unlock(&tasklist_lock); |
| 356 | if (!error) |
| 357 | return copy_siginfo_to_user(data, &lastinfo); |
| 358 | return error; |
| 359 | } |
| 360 | |
| 361 | static int ptrace_setsiginfo(struct task_struct *child, siginfo_t __user * data) |
| 362 | { |
| 363 | siginfo_t newinfo; |
| 364 | int error = -ESRCH; |
| 365 | |
| 366 | if (copy_from_user(&newinfo, data, sizeof (siginfo_t))) |
| 367 | return -EFAULT; |
| 368 | |
| 369 | read_lock(&tasklist_lock); |
| 370 | if (likely(child->sighand != NULL)) { |
| 371 | error = -EINVAL; |
| 372 | spin_lock_irq(&child->sighand->siglock); |
| 373 | if (likely(child->last_siginfo != NULL)) { |
| 374 | *child->last_siginfo = newinfo; |
| 375 | error = 0; |
| 376 | } |
| 377 | spin_unlock_irq(&child->sighand->siglock); |
| 378 | } |
| 379 | read_unlock(&tasklist_lock); |
| 380 | return error; |
| 381 | } |
| 382 | |
| 383 | int ptrace_request(struct task_struct *child, long request, |
| 384 | long addr, long data) |
| 385 | { |
| 386 | int ret = -EIO; |
| 387 | |
| 388 | switch (request) { |
| 389 | #ifdef PTRACE_OLDSETOPTIONS |
| 390 | case PTRACE_OLDSETOPTIONS: |
| 391 | #endif |
| 392 | case PTRACE_SETOPTIONS: |
| 393 | ret = ptrace_setoptions(child, data); |
| 394 | break; |
| 395 | case PTRACE_GETEVENTMSG: |
| 396 | ret = put_user(child->ptrace_message, (unsigned long __user *) data); |
| 397 | break; |
| 398 | case PTRACE_GETSIGINFO: |
| 399 | ret = ptrace_getsiginfo(child, (siginfo_t __user *) data); |
| 400 | break; |
| 401 | case PTRACE_SETSIGINFO: |
| 402 | ret = ptrace_setsiginfo(child, (siginfo_t __user *) data); |
| 403 | break; |
| 404 | default: |
| 405 | break; |
| 406 | } |
| 407 | |
| 408 | return ret; |
| 409 | } |
Christoph Hellwig | 481bed4 | 2005-11-07 00:59:47 -0800 | [diff] [blame] | 410 | |
| 411 | #ifndef __ARCH_SYS_PTRACE |
| 412 | static int ptrace_get_task_struct(long request, long pid, |
| 413 | struct task_struct **childp) |
| 414 | { |
| 415 | struct task_struct *child; |
| 416 | int ret; |
| 417 | |
| 418 | /* |
| 419 | * Callers use child == NULL as an indication to exit early even |
| 420 | * when the return value is 0, so make sure it is non-NULL here. |
| 421 | */ |
| 422 | *childp = NULL; |
| 423 | |
| 424 | if (request == PTRACE_TRACEME) { |
| 425 | /* |
| 426 | * Are we already being traced? |
| 427 | */ |
| 428 | if (current->ptrace & PT_PTRACED) |
| 429 | return -EPERM; |
| 430 | ret = security_ptrace(current->parent, current); |
| 431 | if (ret) |
| 432 | return -EPERM; |
| 433 | /* |
| 434 | * Set the ptrace bit in the process ptrace flags. |
| 435 | */ |
| 436 | current->ptrace |= PT_PTRACED; |
| 437 | return 0; |
| 438 | } |
| 439 | |
| 440 | /* |
| 441 | * You may not mess with init |
| 442 | */ |
| 443 | if (pid == 1) |
| 444 | return -EPERM; |
| 445 | |
| 446 | ret = -ESRCH; |
| 447 | read_lock(&tasklist_lock); |
| 448 | child = find_task_by_pid(pid); |
| 449 | if (child) |
| 450 | get_task_struct(child); |
| 451 | read_unlock(&tasklist_lock); |
| 452 | if (!child) |
| 453 | return -ESRCH; |
| 454 | |
| 455 | *childp = child; |
| 456 | return 0; |
| 457 | } |
| 458 | |
| 459 | asmlinkage long sys_ptrace(long request, long pid, long addr, long data) |
| 460 | { |
| 461 | struct task_struct *child; |
| 462 | long ret; |
| 463 | |
| 464 | /* |
| 465 | * This lock_kernel fixes a subtle race with suid exec |
| 466 | */ |
| 467 | lock_kernel(); |
| 468 | ret = ptrace_get_task_struct(request, pid, &child); |
| 469 | if (!child) |
| 470 | goto out; |
| 471 | |
| 472 | if (request == PTRACE_ATTACH) { |
| 473 | ret = ptrace_attach(child); |
Christoph Hellwig | 005f18d | 2005-11-13 16:06:33 -0800 | [diff] [blame] | 474 | goto out_put_task_struct; |
Christoph Hellwig | 481bed4 | 2005-11-07 00:59:47 -0800 | [diff] [blame] | 475 | } |
| 476 | |
| 477 | ret = ptrace_check_attach(child, request == PTRACE_KILL); |
| 478 | if (ret < 0) |
| 479 | goto out_put_task_struct; |
| 480 | |
| 481 | ret = arch_ptrace(child, request, addr, data); |
| 482 | if (ret < 0) |
| 483 | goto out_put_task_struct; |
| 484 | |
| 485 | out_put_task_struct: |
| 486 | put_task_struct(child); |
| 487 | out: |
| 488 | unlock_kernel(); |
| 489 | return ret; |
| 490 | } |
| 491 | #endif /* __ARCH_SYS_PTRACE */ |