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> 19 #include <linux/signal.h> 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 } 59 spin_unlock(&child->sighand->siglock); 60 } 61 62 /* 63 * unptrace a task: move it back to its original parent and 64 * remove it from the ptrace list. 65 * 66 * Must be called with the tasklist lock write-held. 67 */ 68 void __ptrace_unlink(task_t *child) 69 { 70 if (!child->ptrace) 71 BUG(); 72 child->ptrace = 0; 73 if (!list_empty(&child->ptrace_list)) { 74 list_del_init(&child->ptrace_list); 75 REMOVE_LINKS(child); 76 child->parent = child->real_parent; 77 SET_LINKS(child); 78 } 79 80 if (child->state == TASK_TRACED) 81 ptrace_untrace(child); 82 } 83 84 /* 85 * Check that we have indeed attached to the thing.. 86 */ 87 int ptrace_check_attach(struct task_struct *child, int kill) 88 { 89 int ret = -ESRCH; 90 91 /* 92 * We take the read lock around doing both checks to close a 93 * possible race where someone else was tracing our child and 94 * detached between these two checks. After this locked check, 95 * we are sure that this is our traced child and that can only 96 * be changed by us so it's not changing right after this. 97 */ 98 read_lock(&tasklist_lock); 99 if ((child->ptrace & PT_PTRACED) && child->parent == current && 100 (!(child->ptrace & PT_ATTACHED) || child->real_parent != current) 101 && child->signal != NULL) { 102 ret = 0; 103 spin_lock_irq(&child->sighand->siglock); 104 if (child->state == TASK_STOPPED) { 105 child->state = TASK_TRACED; 106 } else if (child->state != TASK_TRACED && !kill) { 107 ret = -ESRCH; 108 } 109 spin_unlock_irq(&child->sighand->siglock); 110 } 111 read_unlock(&tasklist_lock); 112 113 if (!ret && !kill) { 114 wait_task_inactive(child); 115 } 116 117 /* All systems go.. */ 118 return ret; 119 } 120 121 int ptrace_attach(struct task_struct *task) 122 { 123 int retval; 124 task_lock(task); 125 retval = -EPERM; 126 if (task->pid <= 1) 127 goto bad; 128 if (task == current) 129 goto bad; 130 if (!task->mm) 131 goto bad; 132 if(((current->uid != task->euid) || 133 (current->uid != task->suid) || 134 (current->uid != task->uid) || 135 (current->gid != task->egid) || 136 (current->gid != task->sgid) || 137 (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE)) 138 goto bad; 139 smp_rmb(); 140 if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE)) 141 goto bad; 142 /* the same process cannot be attached many times */ 143 if (task->ptrace & PT_PTRACED) 144 goto bad; 145 retval = security_ptrace(current, task); 146 if (retval) 147 goto bad; 148 149 /* Go */ 150 task->ptrace |= PT_PTRACED | ((task->real_parent != current) 151 ? PT_ATTACHED : 0); 152 if (capable(CAP_SYS_PTRACE)) 153 task->ptrace |= PT_PTRACE_CAP; 154 task_unlock(task); 155 156 write_lock_irq(&tasklist_lock); 157 __ptrace_link(task, current); 158 write_unlock_irq(&tasklist_lock); 159 160 force_sig_specific(SIGSTOP, task); 161 return 0; 162 163 bad: 164 task_unlock(task); 165 return retval; 166 } 167 168 int ptrace_detach(struct task_struct *child, unsigned int data) 169 { 170 if (!valid_signal(data)) 171 return -EIO; 172 173 /* Architecture-specific hardware disable .. */ 174 ptrace_disable(child); 175 176 /* .. re-parent .. */ 177 child->exit_code = data; 178 179 write_lock_irq(&tasklist_lock); 180 __ptrace_unlink(child); 181 /* .. and wake it up. */ 182 if (child->exit_state != EXIT_ZOMBIE) 183 wake_up_process(child); 184 write_unlock_irq(&tasklist_lock); 185 186 return 0; 187 } 188 189 /* 190 * Access another process' address space. 191 * Source/target buffer must be kernel space, 192 * Do not walk the page table directly, use get_user_pages 193 */ 194 195 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) 196 { 197 struct mm_struct *mm; 198 struct vm_area_struct *vma; 199 struct page *page; 200 void *old_buf = buf; 201 202 mm = get_task_mm(tsk); 203 if (!mm) 204 return 0; 205 206 down_read(&mm->mmap_sem); 207 /* ignore errors, just check how much was sucessfully transfered */ 208 while (len) { 209 int bytes, ret, offset; 210 void *maddr; 211 212 ret = get_user_pages(tsk, mm, addr, 1, 213 write, 1, &page, &vma); 214 if (ret <= 0) 215 break; 216 217 bytes = len; 218 offset = addr & (PAGE_SIZE-1); 219 if (bytes > PAGE_SIZE-offset) 220 bytes = PAGE_SIZE-offset; 221 222 maddr = kmap(page); 223 if (write) { 224 copy_to_user_page(vma, page, addr, 225 maddr + offset, buf, bytes); 226 set_page_dirty_lock(page); 227 } else { 228 copy_from_user_page(vma, page, addr, 229 buf, maddr + offset, bytes); 230 } 231 kunmap(page); 232 page_cache_release(page); 233 len -= bytes; 234 buf += bytes; 235 addr += bytes; 236 } 237 up_read(&mm->mmap_sem); 238 mmput(mm); 239 240 return buf - old_buf; 241 } 242 243 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len) 244 { 245 int copied = 0; 246 247 while (len > 0) { 248 char buf[128]; 249 int this_len, retval; 250 251 this_len = (len > sizeof(buf)) ? sizeof(buf) : len; 252 retval = access_process_vm(tsk, src, buf, this_len, 0); 253 if (!retval) { 254 if (copied) 255 break; 256 return -EIO; 257 } 258 if (copy_to_user(dst, buf, retval)) 259 return -EFAULT; 260 copied += retval; 261 src += retval; 262 dst += retval; 263 len -= retval; 264 } 265 return copied; 266 } 267 268 int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len) 269 { 270 int copied = 0; 271 272 while (len > 0) { 273 char buf[128]; 274 int this_len, retval; 275 276 this_len = (len > sizeof(buf)) ? sizeof(buf) : len; 277 if (copy_from_user(buf, src, this_len)) 278 return -EFAULT; 279 retval = access_process_vm(tsk, dst, buf, this_len, 1); 280 if (!retval) { 281 if (copied) 282 break; 283 return -EIO; 284 } 285 copied += retval; 286 src += retval; 287 dst += retval; 288 len -= retval; 289 } 290 return copied; 291 } 292 293 static int ptrace_setoptions(struct task_struct *child, long data) 294 { 295 child->ptrace &= ~PT_TRACE_MASK; 296 297 if (data & PTRACE_O_TRACESYSGOOD) 298 child->ptrace |= PT_TRACESYSGOOD; 299 300 if (data & PTRACE_O_TRACEFORK) 301 child->ptrace |= PT_TRACE_FORK; 302 303 if (data & PTRACE_O_TRACEVFORK) 304 child->ptrace |= PT_TRACE_VFORK; 305 306 if (data & PTRACE_O_TRACECLONE) 307 child->ptrace |= PT_TRACE_CLONE; 308 309 if (data & PTRACE_O_TRACEEXEC) 310 child->ptrace |= PT_TRACE_EXEC; 311 312 if (data & PTRACE_O_TRACEVFORKDONE) 313 child->ptrace |= PT_TRACE_VFORK_DONE; 314 315 if (data & PTRACE_O_TRACEEXIT) 316 child->ptrace |= PT_TRACE_EXIT; 317 318 return (data & ~PTRACE_O_MASK) ? -EINVAL : 0; 319 } 320 321 static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data) 322 { 323 siginfo_t lastinfo; 324 int error = -ESRCH; 325 326 read_lock(&tasklist_lock); 327 if (likely(child->sighand != NULL)) { 328 error = -EINVAL; 329 spin_lock_irq(&child->sighand->siglock); 330 if (likely(child->last_siginfo != NULL)) { 331 lastinfo = *child->last_siginfo; 332 error = 0; 333 } 334 spin_unlock_irq(&child->sighand->siglock); 335 } 336 read_unlock(&tasklist_lock); 337 if (!error) 338 return copy_siginfo_to_user(data, &lastinfo); 339 return error; 340 } 341 342 static int ptrace_setsiginfo(struct task_struct *child, siginfo_t __user * data) 343 { 344 siginfo_t newinfo; 345 int error = -ESRCH; 346 347 if (copy_from_user(&newinfo, data, sizeof (siginfo_t))) 348 return -EFAULT; 349 350 read_lock(&tasklist_lock); 351 if (likely(child->sighand != NULL)) { 352 error = -EINVAL; 353 spin_lock_irq(&child->sighand->siglock); 354 if (likely(child->last_siginfo != NULL)) { 355 *child->last_siginfo = newinfo; 356 error = 0; 357 } 358 spin_unlock_irq(&child->sighand->siglock); 359 } 360 read_unlock(&tasklist_lock); 361 return error; 362 } 363 364 int ptrace_request(struct task_struct *child, long request, 365 long addr, long data) 366 { 367 int ret = -EIO; 368 369 switch (request) { 370 #ifdef PTRACE_OLDSETOPTIONS 371 case PTRACE_OLDSETOPTIONS: 372 #endif 373 case PTRACE_SETOPTIONS: 374 ret = ptrace_setoptions(child, data); 375 break; 376 case PTRACE_GETEVENTMSG: 377 ret = put_user(child->ptrace_message, (unsigned long __user *) data); 378 break; 379 case PTRACE_GETSIGINFO: 380 ret = ptrace_getsiginfo(child, (siginfo_t __user *) data); 381 break; 382 case PTRACE_SETSIGINFO: 383 ret = ptrace_setsiginfo(child, (siginfo_t __user *) data); 384 break; 385 default: 386 break; 387 } 388 389 return ret; 390 } 391