Commit | Line | Data |
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1da177e4 LT |
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 | ||
20 | #include <asm/pgtable.h> | |
21 | #include <asm/uaccess.h> | |
22 | ||
23 | /* | |
24 | * ptrace a task: make the debugger its new parent and | |
25 | * move it to the ptrace list. | |
26 | * | |
27 | * Must be called with the tasklist lock write-held. | |
28 | */ | |
29 | void __ptrace_link(task_t *child, task_t *new_parent) | |
30 | { | |
31 | if (!list_empty(&child->ptrace_list)) | |
32 | BUG(); | |
33 | if (child->parent == new_parent) | |
34 | return; | |
35 | list_add(&child->ptrace_list, &child->parent->ptrace_children); | |
36 | REMOVE_LINKS(child); | |
37 | child->parent = new_parent; | |
38 | SET_LINKS(child); | |
39 | } | |
40 | ||
41 | /* | |
42 | * Turn a tracing stop into a normal stop now, since with no tracer there | |
43 | * would be no way to wake it up with SIGCONT or SIGKILL. If there was a | |
44 | * signal sent that would resume the child, but didn't because it was in | |
45 | * TASK_TRACED, resume it now. | |
46 | * Requires that irqs be disabled. | |
47 | */ | |
48 | void ptrace_untrace(task_t *child) | |
49 | { | |
50 | spin_lock(&child->sighand->siglock); | |
51 | if (child->state == TASK_TRACED) { | |
52 | if (child->signal->flags & SIGNAL_STOP_STOPPED) { | |
53 | child->state = TASK_STOPPED; | |
54 | } else { | |
55 | signal_wake_up(child, 1); | |
56 | } | |
57 | } | |
58 | spin_unlock(&child->sighand->siglock); | |
59 | } | |
60 | ||
61 | /* | |
62 | * unptrace a task: move it back to its original parent and | |
63 | * remove it from the ptrace list. | |
64 | * | |
65 | * Must be called with the tasklist lock write-held. | |
66 | */ | |
67 | void __ptrace_unlink(task_t *child) | |
68 | { | |
69 | if (!child->ptrace) | |
70 | BUG(); | |
71 | child->ptrace = 0; | |
72 | if (!list_empty(&child->ptrace_list)) { | |
73 | list_del_init(&child->ptrace_list); | |
74 | REMOVE_LINKS(child); | |
75 | child->parent = child->real_parent; | |
76 | SET_LINKS(child); | |
77 | } | |
78 | ||
79 | if (child->state == TASK_TRACED) | |
80 | ptrace_untrace(child); | |
81 | } | |
82 | ||
83 | /* | |
84 | * Check that we have indeed attached to the thing.. | |
85 | */ | |
86 | int ptrace_check_attach(struct task_struct *child, int kill) | |
87 | { | |
88 | int ret = -ESRCH; | |
89 | ||
90 | /* | |
91 | * We take the read lock around doing both checks to close a | |
92 | * possible race where someone else was tracing our child and | |
93 | * detached between these two checks. After this locked check, | |
94 | * we are sure that this is our traced child and that can only | |
95 | * be changed by us so it's not changing right after this. | |
96 | */ | |
97 | read_lock(&tasklist_lock); | |
98 | if ((child->ptrace & PT_PTRACED) && child->parent == current && | |
99 | (!(child->ptrace & PT_ATTACHED) || child->real_parent != current) | |
100 | && child->signal != NULL) { | |
101 | ret = 0; | |
102 | spin_lock_irq(&child->sighand->siglock); | |
103 | if (child->state == TASK_STOPPED) { | |
104 | child->state = TASK_TRACED; | |
105 | } else if (child->state != TASK_TRACED && !kill) { | |
106 | ret = -ESRCH; | |
107 | } | |
108 | spin_unlock_irq(&child->sighand->siglock); | |
109 | } | |
110 | read_unlock(&tasklist_lock); | |
111 | ||
112 | if (!ret && !kill) { | |
113 | wait_task_inactive(child); | |
114 | } | |
115 | ||
116 | /* All systems go.. */ | |
117 | return ret; | |
118 | } | |
119 | ||
120 | int ptrace_attach(struct task_struct *task) | |
121 | { | |
122 | int retval; | |
123 | task_lock(task); | |
124 | retval = -EPERM; | |
125 | if (task->pid <= 1) | |
126 | goto bad; | |
127 | if (task == current) | |
128 | goto bad; | |
129 | if (!task->mm) | |
130 | goto bad; | |
131 | if(((current->uid != task->euid) || | |
132 | (current->uid != task->suid) || | |
133 | (current->uid != task->uid) || | |
134 | (current->gid != task->egid) || | |
135 | (current->gid != task->sgid) || | |
136 | (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE)) | |
137 | goto bad; | |
138 | rmb(); | |
139 | if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE)) | |
140 | goto bad; | |
141 | /* the same process cannot be attached many times */ | |
142 | if (task->ptrace & PT_PTRACED) | |
143 | goto bad; | |
144 | retval = security_ptrace(current, task); | |
145 | if (retval) | |
146 | goto bad; | |
147 | ||
148 | /* Go */ | |
149 | task->ptrace |= PT_PTRACED | ((task->real_parent != current) | |
150 | ? PT_ATTACHED : 0); | |
151 | if (capable(CAP_SYS_PTRACE)) | |
152 | task->ptrace |= PT_PTRACE_CAP; | |
153 | task_unlock(task); | |
154 | ||
155 | write_lock_irq(&tasklist_lock); | |
156 | __ptrace_link(task, current); | |
157 | write_unlock_irq(&tasklist_lock); | |
158 | ||
159 | force_sig_specific(SIGSTOP, task); | |
160 | return 0; | |
161 | ||
162 | bad: | |
163 | task_unlock(task); | |
164 | return retval; | |
165 | } | |
166 | ||
167 | int ptrace_detach(struct task_struct *child, unsigned int data) | |
168 | { | |
169 | if ((unsigned long) data > _NSIG) | |
170 | return -EIO; | |
171 | ||
172 | /* Architecture-specific hardware disable .. */ | |
173 | ptrace_disable(child); | |
174 | ||
175 | /* .. re-parent .. */ | |
176 | child->exit_code = data; | |
177 | ||
178 | write_lock_irq(&tasklist_lock); | |
179 | __ptrace_unlink(child); | |
180 | /* .. and wake it up. */ | |
181 | if (child->exit_state != EXIT_ZOMBIE) | |
182 | wake_up_process(child); | |
183 | write_unlock_irq(&tasklist_lock); | |
184 | ||
185 | return 0; | |
186 | } | |
187 | ||
188 | /* | |
189 | * Access another process' address space. | |
190 | * Source/target buffer must be kernel space, | |
191 | * Do not walk the page table directly, use get_user_pages | |
192 | */ | |
193 | ||
194 | int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) | |
195 | { | |
196 | struct mm_struct *mm; | |
197 | struct vm_area_struct *vma; | |
198 | struct page *page; | |
199 | void *old_buf = buf; | |
200 | ||
201 | mm = get_task_mm(tsk); | |
202 | if (!mm) | |
203 | return 0; | |
204 | ||
205 | down_read(&mm->mmap_sem); | |
206 | /* ignore errors, just check how much was sucessfully transfered */ | |
207 | while (len) { | |
208 | int bytes, ret, offset; | |
209 | void *maddr; | |
210 | ||
211 | ret = get_user_pages(tsk, mm, addr, 1, | |
212 | write, 1, &page, &vma); | |
213 | if (ret <= 0) | |
214 | break; | |
215 | ||
216 | bytes = len; | |
217 | offset = addr & (PAGE_SIZE-1); | |
218 | if (bytes > PAGE_SIZE-offset) | |
219 | bytes = PAGE_SIZE-offset; | |
220 | ||
221 | maddr = kmap(page); | |
222 | if (write) { | |
223 | copy_to_user_page(vma, page, addr, | |
224 | maddr + offset, buf, bytes); | |
225 | set_page_dirty_lock(page); | |
226 | } else { | |
227 | copy_from_user_page(vma, page, addr, | |
228 | buf, maddr + offset, bytes); | |
229 | } | |
230 | kunmap(page); | |
231 | page_cache_release(page); | |
232 | len -= bytes; | |
233 | buf += bytes; | |
234 | addr += bytes; | |
235 | } | |
236 | up_read(&mm->mmap_sem); | |
237 | mmput(mm); | |
238 | ||
239 | return buf - old_buf; | |
240 | } | |
241 | ||
242 | int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len) | |
243 | { | |
244 | int copied = 0; | |
245 | ||
246 | while (len > 0) { | |
247 | char buf[128]; | |
248 | int this_len, retval; | |
249 | ||
250 | this_len = (len > sizeof(buf)) ? sizeof(buf) : len; | |
251 | retval = access_process_vm(tsk, src, buf, this_len, 0); | |
252 | if (!retval) { | |
253 | if (copied) | |
254 | break; | |
255 | return -EIO; | |
256 | } | |
257 | if (copy_to_user(dst, buf, retval)) | |
258 | return -EFAULT; | |
259 | copied += retval; | |
260 | src += retval; | |
261 | dst += retval; | |
262 | len -= retval; | |
263 | } | |
264 | return copied; | |
265 | } | |
266 | ||
267 | int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len) | |
268 | { | |
269 | int copied = 0; | |
270 | ||
271 | while (len > 0) { | |
272 | char buf[128]; | |
273 | int this_len, retval; | |
274 | ||
275 | this_len = (len > sizeof(buf)) ? sizeof(buf) : len; | |
276 | if (copy_from_user(buf, src, this_len)) | |
277 | return -EFAULT; | |
278 | retval = access_process_vm(tsk, dst, buf, this_len, 1); | |
279 | if (!retval) { | |
280 | if (copied) | |
281 | break; | |
282 | return -EIO; | |
283 | } | |
284 | copied += retval; | |
285 | src += retval; | |
286 | dst += retval; | |
287 | len -= retval; | |
288 | } | |
289 | return copied; | |
290 | } | |
291 | ||
292 | static int ptrace_setoptions(struct task_struct *child, long data) | |
293 | { | |
294 | child->ptrace &= ~PT_TRACE_MASK; | |
295 | ||
296 | if (data & PTRACE_O_TRACESYSGOOD) | |
297 | child->ptrace |= PT_TRACESYSGOOD; | |
298 | ||
299 | if (data & PTRACE_O_TRACEFORK) | |
300 | child->ptrace |= PT_TRACE_FORK; | |
301 | ||
302 | if (data & PTRACE_O_TRACEVFORK) | |
303 | child->ptrace |= PT_TRACE_VFORK; | |
304 | ||
305 | if (data & PTRACE_O_TRACECLONE) | |
306 | child->ptrace |= PT_TRACE_CLONE; | |
307 | ||
308 | if (data & PTRACE_O_TRACEEXEC) | |
309 | child->ptrace |= PT_TRACE_EXEC; | |
310 | ||
311 | if (data & PTRACE_O_TRACEVFORKDONE) | |
312 | child->ptrace |= PT_TRACE_VFORK_DONE; | |
313 | ||
314 | if (data & PTRACE_O_TRACEEXIT) | |
315 | child->ptrace |= PT_TRACE_EXIT; | |
316 | ||
317 | return (data & ~PTRACE_O_MASK) ? -EINVAL : 0; | |
318 | } | |
319 | ||
320 | static int ptrace_getsiginfo(struct task_struct *child, siginfo_t __user * data) | |
321 | { | |
322 | siginfo_t lastinfo; | |
323 | int error = -ESRCH; | |
324 | ||
325 | read_lock(&tasklist_lock); | |
326 | if (likely(child->sighand != NULL)) { | |
327 | error = -EINVAL; | |
328 | spin_lock_irq(&child->sighand->siglock); | |
329 | if (likely(child->last_siginfo != NULL)) { | |
330 | lastinfo = *child->last_siginfo; | |
331 | error = 0; | |
332 | } | |
333 | spin_unlock_irq(&child->sighand->siglock); | |
334 | } | |
335 | read_unlock(&tasklist_lock); | |
336 | if (!error) | |
337 | return copy_siginfo_to_user(data, &lastinfo); | |
338 | return error; | |
339 | } | |
340 | ||
341 | static int ptrace_setsiginfo(struct task_struct *child, siginfo_t __user * data) | |
342 | { | |
343 | siginfo_t newinfo; | |
344 | int error = -ESRCH; | |
345 | ||
346 | if (copy_from_user(&newinfo, data, sizeof (siginfo_t))) | |
347 | return -EFAULT; | |
348 | ||
349 | read_lock(&tasklist_lock); | |
350 | if (likely(child->sighand != NULL)) { | |
351 | error = -EINVAL; | |
352 | spin_lock_irq(&child->sighand->siglock); | |
353 | if (likely(child->last_siginfo != NULL)) { | |
354 | *child->last_siginfo = newinfo; | |
355 | error = 0; | |
356 | } | |
357 | spin_unlock_irq(&child->sighand->siglock); | |
358 | } | |
359 | read_unlock(&tasklist_lock); | |
360 | return error; | |
361 | } | |
362 | ||
363 | int ptrace_request(struct task_struct *child, long request, | |
364 | long addr, long data) | |
365 | { | |
366 | int ret = -EIO; | |
367 | ||
368 | switch (request) { | |
369 | #ifdef PTRACE_OLDSETOPTIONS | |
370 | case PTRACE_OLDSETOPTIONS: | |
371 | #endif | |
372 | case PTRACE_SETOPTIONS: | |
373 | ret = ptrace_setoptions(child, data); | |
374 | break; | |
375 | case PTRACE_GETEVENTMSG: | |
376 | ret = put_user(child->ptrace_message, (unsigned long __user *) data); | |
377 | break; | |
378 | case PTRACE_GETSIGINFO: | |
379 | ret = ptrace_getsiginfo(child, (siginfo_t __user *) data); | |
380 | break; | |
381 | case PTRACE_SETSIGINFO: | |
382 | ret = ptrace_setsiginfo(child, (siginfo_t __user *) data); | |
383 | break; | |
384 | default: | |
385 | break; | |
386 | } | |
387 | ||
388 | return ret; | |
389 | } |