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-rw-r--r--kernel/ptrace.c389
1 files changed, 389 insertions, 0 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
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index 000000000000..88b306c4e841
--- /dev/null
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@@ -0,0 +1,389 @@
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 */
29void __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 */
48void 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 */
67void __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 */
86int 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
120int 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
162bad:
163 task_unlock(task);
164 return retval;
165}
166
167int 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
194int 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
242int 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
267int 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
292static 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
320static 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
341static 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
363int 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}
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