Line data Source code
1 : /* SPDX-License-Identifier: GPL-2.0 */
2 : #ifndef _LINUX_PTRACE_H
3 : #define _LINUX_PTRACE_H
4 :
5 : #include <linux/compiler.h> /* For unlikely. */
6 : #include <linux/sched.h> /* For struct task_struct. */
7 : #include <linux/sched/signal.h> /* For send_sig(), same_thread_group(), etc. */
8 : #include <linux/err.h> /* for IS_ERR_VALUE */
9 : #include <linux/bug.h> /* For BUG_ON. */
10 : #include <linux/pid_namespace.h> /* For task_active_pid_ns. */
11 : #include <uapi/linux/ptrace.h>
12 : #include <linux/seccomp.h>
13 :
14 : /* Add sp to seccomp_data, as seccomp is user API, we don't want to modify it */
15 : struct syscall_info {
16 : __u64 sp;
17 : struct seccomp_data data;
18 : };
19 :
20 : extern int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,
21 : void *buf, int len, unsigned int gup_flags);
22 :
23 : /*
24 : * Ptrace flags
25 : *
26 : * The owner ship rules for task->ptrace which holds the ptrace
27 : * flags is simple. When a task is running it owns it's task->ptrace
28 : * flags. When the a task is stopped the ptracer owns task->ptrace.
29 : */
30 :
31 : #define PT_SEIZED 0x00010000 /* SEIZE used, enable new behavior */
32 : #define PT_PTRACED 0x00000001
33 :
34 : #define PT_OPT_FLAG_SHIFT 3
35 : /* PT_TRACE_* event enable flags */
36 : #define PT_EVENT_FLAG(event) (1 << (PT_OPT_FLAG_SHIFT + (event)))
37 : #define PT_TRACESYSGOOD PT_EVENT_FLAG(0)
38 : #define PT_TRACE_FORK PT_EVENT_FLAG(PTRACE_EVENT_FORK)
39 : #define PT_TRACE_VFORK PT_EVENT_FLAG(PTRACE_EVENT_VFORK)
40 : #define PT_TRACE_CLONE PT_EVENT_FLAG(PTRACE_EVENT_CLONE)
41 : #define PT_TRACE_EXEC PT_EVENT_FLAG(PTRACE_EVENT_EXEC)
42 : #define PT_TRACE_VFORK_DONE PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE)
43 : #define PT_TRACE_EXIT PT_EVENT_FLAG(PTRACE_EVENT_EXIT)
44 : #define PT_TRACE_SECCOMP PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP)
45 :
46 : #define PT_EXITKILL (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
47 : #define PT_SUSPEND_SECCOMP (PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT)
48 :
49 : extern long arch_ptrace(struct task_struct *child, long request,
50 : unsigned long addr, unsigned long data);
51 : extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);
52 : extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len);
53 : extern void ptrace_disable(struct task_struct *);
54 : extern int ptrace_request(struct task_struct *child, long request,
55 : unsigned long addr, unsigned long data);
56 : extern int ptrace_notify(int exit_code, unsigned long message);
57 : extern void __ptrace_link(struct task_struct *child,
58 : struct task_struct *new_parent,
59 : const struct cred *ptracer_cred);
60 : extern void __ptrace_unlink(struct task_struct *child);
61 : extern void exit_ptrace(struct task_struct *tracer, struct list_head *dead);
62 : #define PTRACE_MODE_READ 0x01
63 : #define PTRACE_MODE_ATTACH 0x02
64 : #define PTRACE_MODE_NOAUDIT 0x04
65 : #define PTRACE_MODE_FSCREDS 0x08
66 : #define PTRACE_MODE_REALCREDS 0x10
67 :
68 : /* shorthands for READ/ATTACH and FSCREDS/REALCREDS combinations */
69 : #define PTRACE_MODE_READ_FSCREDS (PTRACE_MODE_READ | PTRACE_MODE_FSCREDS)
70 : #define PTRACE_MODE_READ_REALCREDS (PTRACE_MODE_READ | PTRACE_MODE_REALCREDS)
71 : #define PTRACE_MODE_ATTACH_FSCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_FSCREDS)
72 : #define PTRACE_MODE_ATTACH_REALCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_REALCREDS)
73 :
74 : /**
75 : * ptrace_may_access - check whether the caller is permitted to access
76 : * a target task.
77 : * @task: target task
78 : * @mode: selects type of access and caller credentials
79 : *
80 : * Returns true on success, false on denial.
81 : *
82 : * One of the flags PTRACE_MODE_FSCREDS and PTRACE_MODE_REALCREDS must
83 : * be set in @mode to specify whether the access was requested through
84 : * a filesystem syscall (should use effective capabilities and fsuid
85 : * of the caller) or through an explicit syscall such as
86 : * process_vm_writev or ptrace (and should use the real credentials).
87 : */
88 : extern bool ptrace_may_access(struct task_struct *task, unsigned int mode);
89 :
90 : static inline int ptrace_reparented(struct task_struct *child)
91 : {
92 0 : return !same_thread_group(child->real_parent, child->parent);
93 : }
94 :
95 : static inline void ptrace_unlink(struct task_struct *child)
96 : {
97 325 : if (unlikely(child->ptrace))
98 0 : __ptrace_unlink(child);
99 : }
100 :
101 : int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
102 : unsigned long data);
103 : int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
104 : unsigned long data);
105 :
106 : /**
107 : * ptrace_parent - return the task that is tracing the given task
108 : * @task: task to consider
109 : *
110 : * Returns %NULL if no one is tracing @task, or the &struct task_struct
111 : * pointer to its tracer.
112 : *
113 : * Must called under rcu_read_lock(). The pointer returned might be kept
114 : * live only by RCU. During exec, this may be called with task_lock() held
115 : * on @task, still held from when check_unsafe_exec() was called.
116 : */
117 : static inline struct task_struct *ptrace_parent(struct task_struct *task)
118 : {
119 0 : if (unlikely(task->ptrace))
120 0 : return rcu_dereference(task->parent);
121 : return NULL;
122 : }
123 :
124 : /**
125 : * ptrace_event_enabled - test whether a ptrace event is enabled
126 : * @task: ptracee of interest
127 : * @event: %PTRACE_EVENT_* to test
128 : *
129 : * Test whether @event is enabled for ptracee @task.
130 : *
131 : * Returns %true if @event is enabled, %false otherwise.
132 : */
133 : static inline bool ptrace_event_enabled(struct task_struct *task, int event)
134 : {
135 325 : return task->ptrace & PT_EVENT_FLAG(event);
136 : }
137 :
138 : /**
139 : * ptrace_event - possibly stop for a ptrace event notification
140 : * @event: %PTRACE_EVENT_* value to report
141 : * @message: value for %PTRACE_GETEVENTMSG to return
142 : *
143 : * Check whether @event is enabled and, if so, report @event and @message
144 : * to the ptrace parent.
145 : *
146 : * Called without locks.
147 : */
148 325 : static inline void ptrace_event(int event, unsigned long message)
149 : {
150 650 : if (unlikely(ptrace_event_enabled(current, event))) {
151 0 : ptrace_notify((event << 8) | SIGTRAP, message);
152 325 : } else if (event == PTRACE_EVENT_EXEC) {
153 : /* legacy EXEC report via SIGTRAP */
154 0 : if ((current->ptrace & (PT_PTRACED|PT_SEIZED)) == PT_PTRACED)
155 0 : send_sig(SIGTRAP, current, 0);
156 : }
157 325 : }
158 :
159 : /**
160 : * ptrace_event_pid - possibly stop for a ptrace event notification
161 : * @event: %PTRACE_EVENT_* value to report
162 : * @pid: process identifier for %PTRACE_GETEVENTMSG to return
163 : *
164 : * Check whether @event is enabled and, if so, report @event and @pid
165 : * to the ptrace parent. @pid is reported as the pid_t seen from the
166 : * ptrace parent's pid namespace.
167 : *
168 : * Called without locks.
169 : */
170 0 : static inline void ptrace_event_pid(int event, struct pid *pid)
171 : {
172 : /*
173 : * FIXME: There's a potential race if a ptracer in a different pid
174 : * namespace than parent attaches between computing message below and
175 : * when we acquire tasklist_lock in ptrace_stop(). If this happens,
176 : * the ptracer will get a bogus pid from PTRACE_GETEVENTMSG.
177 : */
178 0 : unsigned long message = 0;
179 : struct pid_namespace *ns;
180 :
181 : rcu_read_lock();
182 0 : ns = task_active_pid_ns(rcu_dereference(current->parent));
183 0 : if (ns)
184 0 : message = pid_nr_ns(pid, ns);
185 : rcu_read_unlock();
186 :
187 0 : ptrace_event(event, message);
188 0 : }
189 :
190 : /**
191 : * ptrace_init_task - initialize ptrace state for a new child
192 : * @child: new child task
193 : * @ptrace: true if child should be ptrace'd by parent's tracer
194 : *
195 : * This is called immediately after adding @child to its parent's children
196 : * list. @ptrace is false in the normal case, and true to ptrace @child.
197 : *
198 : * Called with current's siglock and write_lock_irq(&tasklist_lock) held.
199 : */
200 340 : static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
201 : {
202 680 : INIT_LIST_HEAD(&child->ptrace_entry);
203 680 : INIT_LIST_HEAD(&child->ptraced);
204 340 : child->jobctl = 0;
205 340 : child->ptrace = 0;
206 340 : child->parent = child->real_parent;
207 :
208 340 : if (unlikely(ptrace) && current->ptrace) {
209 0 : child->ptrace = current->ptrace;
210 0 : __ptrace_link(child, current->parent, current->ptracer_cred);
211 :
212 0 : if (child->ptrace & PT_SEIZED)
213 0 : task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
214 : else
215 0 : sigaddset(&child->pending.signal, SIGSTOP);
216 : }
217 : else
218 340 : child->ptracer_cred = NULL;
219 340 : }
220 :
221 : /**
222 : * ptrace_release_task - final ptrace-related cleanup of a zombie being reaped
223 : * @task: task in %EXIT_DEAD state
224 : *
225 : * Called with write_lock(&tasklist_lock) held.
226 : */
227 325 : static inline void ptrace_release_task(struct task_struct *task)
228 : {
229 650 : BUG_ON(!list_empty(&task->ptraced));
230 325 : ptrace_unlink(task);
231 650 : BUG_ON(!list_empty(&task->ptrace_entry));
232 325 : }
233 :
234 : #ifndef force_successful_syscall_return
235 : /*
236 : * System call handlers that, upon successful completion, need to return a
237 : * negative value should call force_successful_syscall_return() right before
238 : * returning. On architectures where the syscall convention provides for a
239 : * separate error flag (e.g., alpha, ia64, ppc{,64}, sparc{,64}, possibly
240 : * others), this macro can be used to ensure that the error flag will not get
241 : * set. On architectures which do not support a separate error flag, the macro
242 : * is a no-op and the spurious error condition needs to be filtered out by some
243 : * other means (e.g., in user-level, by passing an extra argument to the
244 : * syscall handler, or something along those lines).
245 : */
246 : #define force_successful_syscall_return() do { } while (0)
247 : #endif
248 :
249 : #ifndef is_syscall_success
250 : /*
251 : * On most systems we can tell if a syscall is a success based on if the retval
252 : * is an error value. On some systems like ia64 and powerpc they have different
253 : * indicators of success/failure and must define their own.
254 : */
255 : #define is_syscall_success(regs) (!IS_ERR_VALUE((unsigned long)(regs_return_value(regs))))
256 : #endif
257 :
258 : /*
259 : * <asm/ptrace.h> should define the following things inside #ifdef __KERNEL__.
260 : *
261 : * These do-nothing inlines are used when the arch does not
262 : * implement single-step. The kerneldoc comments are here
263 : * to document the interface for all arch definitions.
264 : */
265 :
266 : #ifndef arch_has_single_step
267 : /**
268 : * arch_has_single_step - does this CPU support user-mode single-step?
269 : *
270 : * If this is defined, then there must be function declarations or
271 : * inlines for user_enable_single_step() and user_disable_single_step().
272 : * arch_has_single_step() should evaluate to nonzero iff the machine
273 : * supports instruction single-step for user mode.
274 : * It can be a constant or it can test a CPU feature bit.
275 : */
276 : #define arch_has_single_step() (0)
277 :
278 : /**
279 : * user_enable_single_step - single-step in user-mode task
280 : * @task: either current or a task stopped in %TASK_TRACED
281 : *
282 : * This can only be called when arch_has_single_step() has returned nonzero.
283 : * Set @task so that when it returns to user mode, it will trap after the
284 : * next single instruction executes. If arch_has_block_step() is defined,
285 : * this must clear the effects of user_enable_block_step() too.
286 : */
287 : static inline void user_enable_single_step(struct task_struct *task)
288 : {
289 : BUG(); /* This can never be called. */
290 : }
291 :
292 : /**
293 : * user_disable_single_step - cancel user-mode single-step
294 : * @task: either current or a task stopped in %TASK_TRACED
295 : *
296 : * Clear @task of the effects of user_enable_single_step() and
297 : * user_enable_block_step(). This can be called whether or not either
298 : * of those was ever called on @task, and even if arch_has_single_step()
299 : * returned zero.
300 : */
301 : static inline void user_disable_single_step(struct task_struct *task)
302 : {
303 : }
304 : #else
305 : extern void user_enable_single_step(struct task_struct *);
306 : extern void user_disable_single_step(struct task_struct *);
307 : #endif /* arch_has_single_step */
308 :
309 : #ifndef arch_has_block_step
310 : /**
311 : * arch_has_block_step - does this CPU support user-mode block-step?
312 : *
313 : * If this is defined, then there must be a function declaration or inline
314 : * for user_enable_block_step(), and arch_has_single_step() must be defined
315 : * too. arch_has_block_step() should evaluate to nonzero iff the machine
316 : * supports step-until-branch for user mode. It can be a constant or it
317 : * can test a CPU feature bit.
318 : */
319 : #define arch_has_block_step() (0)
320 :
321 : /**
322 : * user_enable_block_step - step until branch in user-mode task
323 : * @task: either current or a task stopped in %TASK_TRACED
324 : *
325 : * This can only be called when arch_has_block_step() has returned nonzero,
326 : * and will never be called when single-instruction stepping is being used.
327 : * Set @task so that when it returns to user mode, it will trap after the
328 : * next branch or trap taken.
329 : */
330 : static inline void user_enable_block_step(struct task_struct *task)
331 : {
332 : BUG(); /* This can never be called. */
333 : }
334 : #else
335 : extern void user_enable_block_step(struct task_struct *);
336 : #endif /* arch_has_block_step */
337 :
338 : #ifdef ARCH_HAS_USER_SINGLE_STEP_REPORT
339 : extern void user_single_step_report(struct pt_regs *regs);
340 : #else
341 : static inline void user_single_step_report(struct pt_regs *regs)
342 : {
343 : kernel_siginfo_t info;
344 : clear_siginfo(&info);
345 : info.si_signo = SIGTRAP;
346 : info.si_errno = 0;
347 : info.si_code = SI_USER;
348 : info.si_pid = 0;
349 : info.si_uid = 0;
350 : force_sig_info(&info);
351 : }
352 : #endif
353 :
354 : #ifndef arch_ptrace_stop_needed
355 : /**
356 : * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
357 : *
358 : * This is called with the siglock held, to decide whether or not it's
359 : * necessary to release the siglock and call arch_ptrace_stop(). It can be
360 : * defined to a constant if arch_ptrace_stop() is never required, or always
361 : * is. On machines where this makes sense, it should be defined to a quick
362 : * test to optimize out calling arch_ptrace_stop() when it would be
363 : * superfluous. For example, if the thread has not been back to user mode
364 : * since the last stop, the thread state might indicate that nothing needs
365 : * to be done.
366 : *
367 : * This is guaranteed to be invoked once before a task stops for ptrace and
368 : * may include arch-specific operations necessary prior to a ptrace stop.
369 : */
370 : #define arch_ptrace_stop_needed() (0)
371 : #endif
372 :
373 : #ifndef arch_ptrace_stop
374 : /**
375 : * arch_ptrace_stop - Do machine-specific work before stopping for ptrace
376 : *
377 : * This is called with no locks held when arch_ptrace_stop_needed() has
378 : * just returned nonzero. It is allowed to block, e.g. for user memory
379 : * access. The arch can have machine-specific work to be done before
380 : * ptrace stops. On ia64, register backing store gets written back to user
381 : * memory here. Since this can be costly (requires dropping the siglock),
382 : * we only do it when the arch requires it for this particular stop, as
383 : * indicated by arch_ptrace_stop_needed().
384 : */
385 : #define arch_ptrace_stop() do { } while (0)
386 : #endif
387 :
388 : #ifndef current_pt_regs
389 : #define current_pt_regs() task_pt_regs(current)
390 : #endif
391 :
392 : #ifndef current_user_stack_pointer
393 : #define current_user_stack_pointer() user_stack_pointer(current_pt_regs())
394 : #endif
395 :
396 : extern int task_current_syscall(struct task_struct *target, struct syscall_info *info);
397 :
398 : extern void sigaction_compat_abi(struct k_sigaction *act, struct k_sigaction *oact);
399 :
400 : /*
401 : * ptrace report for syscall entry and exit looks identical.
402 : */
403 0 : static inline int ptrace_report_syscall(unsigned long message)
404 : {
405 0 : int ptrace = current->ptrace;
406 : int signr;
407 :
408 0 : if (!(ptrace & PT_PTRACED))
409 : return 0;
410 :
411 0 : signr = ptrace_notify(SIGTRAP | ((ptrace & PT_TRACESYSGOOD) ? 0x80 : 0),
412 : message);
413 :
414 : /*
415 : * this isn't the same as continuing with a signal, but it will do
416 : * for normal use. strace only continues with a signal if the
417 : * stopping signal is not SIGTRAP. -brl
418 : */
419 0 : if (signr)
420 0 : send_sig(signr, current, 1);
421 :
422 0 : return fatal_signal_pending(current);
423 : }
424 :
425 : /**
426 : * ptrace_report_syscall_entry - task is about to attempt a system call
427 : * @regs: user register state of current task
428 : *
429 : * This will be called if %SYSCALL_WORK_SYSCALL_TRACE or
430 : * %SYSCALL_WORK_SYSCALL_EMU have been set, when the current task has just
431 : * entered the kernel for a system call. Full user register state is
432 : * available here. Changing the values in @regs can affect the system
433 : * call number and arguments to be tried. It is safe to block here,
434 : * preventing the system call from beginning.
435 : *
436 : * Returns zero normally, or nonzero if the calling arch code should abort
437 : * the system call. That must prevent normal entry so no system call is
438 : * made. If @task ever returns to user mode after this, its register state
439 : * is unspecified, but should be something harmless like an %ENOSYS error
440 : * return. It should preserve enough information so that syscall_rollback()
441 : * can work (see asm-generic/syscall.h).
442 : *
443 : * Called without locks, just after entering kernel mode.
444 : */
445 : static inline __must_check int ptrace_report_syscall_entry(
446 : struct pt_regs *regs)
447 : {
448 0 : return ptrace_report_syscall(PTRACE_EVENTMSG_SYSCALL_ENTRY);
449 : }
450 :
451 : /**
452 : * ptrace_report_syscall_exit - task has just finished a system call
453 : * @regs: user register state of current task
454 : * @step: nonzero if simulating single-step or block-step
455 : *
456 : * This will be called if %SYSCALL_WORK_SYSCALL_TRACE has been set, when
457 : * the current task has just finished an attempted system call. Full
458 : * user register state is available here. It is safe to block here,
459 : * preventing signals from being processed.
460 : *
461 : * If @step is nonzero, this report is also in lieu of the normal
462 : * trap that would follow the system call instruction because
463 : * user_enable_block_step() or user_enable_single_step() was used.
464 : * In this case, %SYSCALL_WORK_SYSCALL_TRACE might not be set.
465 : *
466 : * Called without locks, just before checking for pending signals.
467 : */
468 : static inline void ptrace_report_syscall_exit(struct pt_regs *regs, int step)
469 : {
470 : if (step)
471 : user_single_step_report(regs);
472 : else
473 0 : ptrace_report_syscall(PTRACE_EVENTMSG_SYSCALL_EXIT);
474 : }
475 : #endif
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