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 : #define PT_DTRACE 0x00000002 /* delayed trace (used on m68k, i386) */
34 :
35 : #define PT_OPT_FLAG_SHIFT 3
36 : /* PT_TRACE_* event enable flags */
37 : #define PT_EVENT_FLAG(event) (1 << (PT_OPT_FLAG_SHIFT + (event)))
38 : #define PT_TRACESYSGOOD PT_EVENT_FLAG(0)
39 : #define PT_TRACE_FORK PT_EVENT_FLAG(PTRACE_EVENT_FORK)
40 : #define PT_TRACE_VFORK PT_EVENT_FLAG(PTRACE_EVENT_VFORK)
41 : #define PT_TRACE_CLONE PT_EVENT_FLAG(PTRACE_EVENT_CLONE)
42 : #define PT_TRACE_EXEC PT_EVENT_FLAG(PTRACE_EVENT_EXEC)
43 : #define PT_TRACE_VFORK_DONE PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE)
44 : #define PT_TRACE_EXIT PT_EVENT_FLAG(PTRACE_EVENT_EXIT)
45 : #define PT_TRACE_SECCOMP PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP)
46 :
47 : #define PT_EXITKILL (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
48 : #define PT_SUSPEND_SECCOMP (PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT)
49 :
50 : /* single stepping state bits (used on ARM and PA-RISC) */
51 : #define PT_SINGLESTEP_BIT 31
52 : #define PT_SINGLESTEP (1<<PT_SINGLESTEP_BIT)
53 : #define PT_BLOCKSTEP_BIT 30
54 : #define PT_BLOCKSTEP (1<<PT_BLOCKSTEP_BIT)
55 :
56 : extern long arch_ptrace(struct task_struct *child, long request,
57 : unsigned long addr, unsigned long data);
58 : extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);
59 : extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len);
60 : extern void ptrace_disable(struct task_struct *);
61 : extern int ptrace_request(struct task_struct *child, long request,
62 : unsigned long addr, unsigned long data);
63 : extern int ptrace_notify(int exit_code, unsigned long message);
64 : extern void __ptrace_link(struct task_struct *child,
65 : struct task_struct *new_parent,
66 : const struct cred *ptracer_cred);
67 : extern void __ptrace_unlink(struct task_struct *child);
68 : extern void exit_ptrace(struct task_struct *tracer, struct list_head *dead);
69 : #define PTRACE_MODE_READ 0x01
70 : #define PTRACE_MODE_ATTACH 0x02
71 : #define PTRACE_MODE_NOAUDIT 0x04
72 : #define PTRACE_MODE_FSCREDS 0x08
73 : #define PTRACE_MODE_REALCREDS 0x10
74 :
75 : /* shorthands for READ/ATTACH and FSCREDS/REALCREDS combinations */
76 : #define PTRACE_MODE_READ_FSCREDS (PTRACE_MODE_READ | PTRACE_MODE_FSCREDS)
77 : #define PTRACE_MODE_READ_REALCREDS (PTRACE_MODE_READ | PTRACE_MODE_REALCREDS)
78 : #define PTRACE_MODE_ATTACH_FSCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_FSCREDS)
79 : #define PTRACE_MODE_ATTACH_REALCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_REALCREDS)
80 :
81 : /**
82 : * ptrace_may_access - check whether the caller is permitted to access
83 : * a target task.
84 : * @task: target task
85 : * @mode: selects type of access and caller credentials
86 : *
87 : * Returns true on success, false on denial.
88 : *
89 : * One of the flags PTRACE_MODE_FSCREDS and PTRACE_MODE_REALCREDS must
90 : * be set in @mode to specify whether the access was requested through
91 : * a filesystem syscall (should use effective capabilities and fsuid
92 : * of the caller) or through an explicit syscall such as
93 : * process_vm_writev or ptrace (and should use the real credentials).
94 : */
95 : extern bool ptrace_may_access(struct task_struct *task, unsigned int mode);
96 :
97 : static inline int ptrace_reparented(struct task_struct *child)
98 : {
99 0 : return !same_thread_group(child->real_parent, child->parent);
100 : }
101 :
102 : static inline void ptrace_unlink(struct task_struct *child)
103 : {
104 93 : if (unlikely(child->ptrace))
105 0 : __ptrace_unlink(child);
106 : }
107 :
108 : int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
109 : unsigned long data);
110 : int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
111 : unsigned long data);
112 :
113 : /**
114 : * ptrace_parent - return the task that is tracing the given task
115 : * @task: task to consider
116 : *
117 : * Returns %NULL if no one is tracing @task, or the &struct task_struct
118 : * pointer to its tracer.
119 : *
120 : * Must called under rcu_read_lock(). The pointer returned might be kept
121 : * live only by RCU. During exec, this may be called with task_lock() held
122 : * on @task, still held from when check_unsafe_exec() was called.
123 : */
124 : static inline struct task_struct *ptrace_parent(struct task_struct *task)
125 : {
126 0 : if (unlikely(task->ptrace))
127 0 : return rcu_dereference(task->parent);
128 : return NULL;
129 : }
130 :
131 : /**
132 : * ptrace_event_enabled - test whether a ptrace event is enabled
133 : * @task: ptracee of interest
134 : * @event: %PTRACE_EVENT_* to test
135 : *
136 : * Test whether @event is enabled for ptracee @task.
137 : *
138 : * Returns %true if @event is enabled, %false otherwise.
139 : */
140 : static inline bool ptrace_event_enabled(struct task_struct *task, int event)
141 : {
142 93 : return task->ptrace & PT_EVENT_FLAG(event);
143 : }
144 :
145 : /**
146 : * ptrace_event - possibly stop for a ptrace event notification
147 : * @event: %PTRACE_EVENT_* value to report
148 : * @message: value for %PTRACE_GETEVENTMSG to return
149 : *
150 : * Check whether @event is enabled and, if so, report @event and @message
151 : * to the ptrace parent.
152 : *
153 : * Called without locks.
154 : */
155 93 : static inline void ptrace_event(int event, unsigned long message)
156 : {
157 186 : if (unlikely(ptrace_event_enabled(current, event))) {
158 0 : ptrace_notify((event << 8) | SIGTRAP, message);
159 93 : } else if (event == PTRACE_EVENT_EXEC) {
160 : /* legacy EXEC report via SIGTRAP */
161 0 : if ((current->ptrace & (PT_PTRACED|PT_SEIZED)) == PT_PTRACED)
162 0 : send_sig(SIGTRAP, current, 0);
163 : }
164 93 : }
165 :
166 : /**
167 : * ptrace_event_pid - possibly stop for a ptrace event notification
168 : * @event: %PTRACE_EVENT_* value to report
169 : * @pid: process identifier for %PTRACE_GETEVENTMSG to return
170 : *
171 : * Check whether @event is enabled and, if so, report @event and @pid
172 : * to the ptrace parent. @pid is reported as the pid_t seen from the
173 : * ptrace parent's pid namespace.
174 : *
175 : * Called without locks.
176 : */
177 0 : static inline void ptrace_event_pid(int event, struct pid *pid)
178 : {
179 : /*
180 : * FIXME: There's a potential race if a ptracer in a different pid
181 : * namespace than parent attaches between computing message below and
182 : * when we acquire tasklist_lock in ptrace_stop(). If this happens,
183 : * the ptracer will get a bogus pid from PTRACE_GETEVENTMSG.
184 : */
185 0 : unsigned long message = 0;
186 : struct pid_namespace *ns;
187 :
188 : rcu_read_lock();
189 0 : ns = task_active_pid_ns(rcu_dereference(current->parent));
190 0 : if (ns)
191 0 : message = pid_nr_ns(pid, ns);
192 : rcu_read_unlock();
193 :
194 0 : ptrace_event(event, message);
195 0 : }
196 :
197 : /**
198 : * ptrace_init_task - initialize ptrace state for a new child
199 : * @child: new child task
200 : * @ptrace: true if child should be ptrace'd by parent's tracer
201 : *
202 : * This is called immediately after adding @child to its parent's children
203 : * list. @ptrace is false in the normal case, and true to ptrace @child.
204 : *
205 : * Called with current's siglock and write_lock_irq(&tasklist_lock) held.
206 : */
207 107 : static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
208 : {
209 214 : INIT_LIST_HEAD(&child->ptrace_entry);
210 214 : INIT_LIST_HEAD(&child->ptraced);
211 107 : child->jobctl = 0;
212 107 : child->ptrace = 0;
213 107 : child->parent = child->real_parent;
214 :
215 107 : if (unlikely(ptrace) && current->ptrace) {
216 0 : child->ptrace = current->ptrace;
217 0 : __ptrace_link(child, current->parent, current->ptracer_cred);
218 :
219 0 : if (child->ptrace & PT_SEIZED)
220 0 : task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
221 : else
222 0 : sigaddset(&child->pending.signal, SIGSTOP);
223 : }
224 : else
225 107 : child->ptracer_cred = NULL;
226 107 : }
227 :
228 : /**
229 : * ptrace_release_task - final ptrace-related cleanup of a zombie being reaped
230 : * @task: task in %EXIT_DEAD state
231 : *
232 : * Called with write_lock(&tasklist_lock) held.
233 : */
234 93 : static inline void ptrace_release_task(struct task_struct *task)
235 : {
236 186 : BUG_ON(!list_empty(&task->ptraced));
237 93 : ptrace_unlink(task);
238 186 : BUG_ON(!list_empty(&task->ptrace_entry));
239 93 : }
240 :
241 : #ifndef force_successful_syscall_return
242 : /*
243 : * System call handlers that, upon successful completion, need to return a
244 : * negative value should call force_successful_syscall_return() right before
245 : * returning. On architectures where the syscall convention provides for a
246 : * separate error flag (e.g., alpha, ia64, ppc{,64}, sparc{,64}, possibly
247 : * others), this macro can be used to ensure that the error flag will not get
248 : * set. On architectures which do not support a separate error flag, the macro
249 : * is a no-op and the spurious error condition needs to be filtered out by some
250 : * other means (e.g., in user-level, by passing an extra argument to the
251 : * syscall handler, or something along those lines).
252 : */
253 : #define force_successful_syscall_return() do { } while (0)
254 : #endif
255 :
256 : #ifndef is_syscall_success
257 : /*
258 : * On most systems we can tell if a syscall is a success based on if the retval
259 : * is an error value. On some systems like ia64 and powerpc they have different
260 : * indicators of success/failure and must define their own.
261 : */
262 : #define is_syscall_success(regs) (!IS_ERR_VALUE((unsigned long)(regs_return_value(regs))))
263 : #endif
264 :
265 : /*
266 : * <asm/ptrace.h> should define the following things inside #ifdef __KERNEL__.
267 : *
268 : * These do-nothing inlines are used when the arch does not
269 : * implement single-step. The kerneldoc comments are here
270 : * to document the interface for all arch definitions.
271 : */
272 :
273 : #ifndef arch_has_single_step
274 : /**
275 : * arch_has_single_step - does this CPU support user-mode single-step?
276 : *
277 : * If this is defined, then there must be function declarations or
278 : * inlines for user_enable_single_step() and user_disable_single_step().
279 : * arch_has_single_step() should evaluate to nonzero iff the machine
280 : * supports instruction single-step for user mode.
281 : * It can be a constant or it can test a CPU feature bit.
282 : */
283 : #define arch_has_single_step() (0)
284 :
285 : /**
286 : * user_enable_single_step - single-step in user-mode task
287 : * @task: either current or a task stopped in %TASK_TRACED
288 : *
289 : * This can only be called when arch_has_single_step() has returned nonzero.
290 : * Set @task so that when it returns to user mode, it will trap after the
291 : * next single instruction executes. If arch_has_block_step() is defined,
292 : * this must clear the effects of user_enable_block_step() too.
293 : */
294 : static inline void user_enable_single_step(struct task_struct *task)
295 : {
296 : BUG(); /* This can never be called. */
297 : }
298 :
299 : /**
300 : * user_disable_single_step - cancel user-mode single-step
301 : * @task: either current or a task stopped in %TASK_TRACED
302 : *
303 : * Clear @task of the effects of user_enable_single_step() and
304 : * user_enable_block_step(). This can be called whether or not either
305 : * of those was ever called on @task, and even if arch_has_single_step()
306 : * returned zero.
307 : */
308 : static inline void user_disable_single_step(struct task_struct *task)
309 : {
310 : }
311 : #else
312 : extern void user_enable_single_step(struct task_struct *);
313 : extern void user_disable_single_step(struct task_struct *);
314 : #endif /* arch_has_single_step */
315 :
316 : #ifndef arch_has_block_step
317 : /**
318 : * arch_has_block_step - does this CPU support user-mode block-step?
319 : *
320 : * If this is defined, then there must be a function declaration or inline
321 : * for user_enable_block_step(), and arch_has_single_step() must be defined
322 : * too. arch_has_block_step() should evaluate to nonzero iff the machine
323 : * supports step-until-branch for user mode. It can be a constant or it
324 : * can test a CPU feature bit.
325 : */
326 : #define arch_has_block_step() (0)
327 :
328 : /**
329 : * user_enable_block_step - step until branch in user-mode task
330 : * @task: either current or a task stopped in %TASK_TRACED
331 : *
332 : * This can only be called when arch_has_block_step() has returned nonzero,
333 : * and will never be called when single-instruction stepping is being used.
334 : * Set @task so that when it returns to user mode, it will trap after the
335 : * next branch or trap taken.
336 : */
337 : static inline void user_enable_block_step(struct task_struct *task)
338 : {
339 : BUG(); /* This can never be called. */
340 : }
341 : #else
342 : extern void user_enable_block_step(struct task_struct *);
343 : #endif /* arch_has_block_step */
344 :
345 : #ifdef ARCH_HAS_USER_SINGLE_STEP_REPORT
346 : extern void user_single_step_report(struct pt_regs *regs);
347 : #else
348 : static inline void user_single_step_report(struct pt_regs *regs)
349 : {
350 : kernel_siginfo_t info;
351 : clear_siginfo(&info);
352 : info.si_signo = SIGTRAP;
353 : info.si_errno = 0;
354 : info.si_code = SI_USER;
355 : info.si_pid = 0;
356 : info.si_uid = 0;
357 : force_sig_info(&info);
358 : }
359 : #endif
360 :
361 : #ifndef arch_ptrace_stop_needed
362 : /**
363 : * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
364 : *
365 : * This is called with the siglock held, to decide whether or not it's
366 : * necessary to release the siglock and call arch_ptrace_stop(). It can be
367 : * defined to a constant if arch_ptrace_stop() is never required, or always
368 : * is. On machines where this makes sense, it should be defined to a quick
369 : * test to optimize out calling arch_ptrace_stop() when it would be
370 : * superfluous. For example, if the thread has not been back to user mode
371 : * since the last stop, the thread state might indicate that nothing needs
372 : * to be done.
373 : *
374 : * This is guaranteed to be invoked once before a task stops for ptrace and
375 : * may include arch-specific operations necessary prior to a ptrace stop.
376 : */
377 : #define arch_ptrace_stop_needed() (0)
378 : #endif
379 :
380 : #ifndef arch_ptrace_stop
381 : /**
382 : * arch_ptrace_stop - Do machine-specific work before stopping for ptrace
383 : *
384 : * This is called with no locks held when arch_ptrace_stop_needed() has
385 : * just returned nonzero. It is allowed to block, e.g. for user memory
386 : * access. The arch can have machine-specific work to be done before
387 : * ptrace stops. On ia64, register backing store gets written back to user
388 : * memory here. Since this can be costly (requires dropping the siglock),
389 : * we only do it when the arch requires it for this particular stop, as
390 : * indicated by arch_ptrace_stop_needed().
391 : */
392 : #define arch_ptrace_stop() do { } while (0)
393 : #endif
394 :
395 : #ifndef current_pt_regs
396 : #define current_pt_regs() task_pt_regs(current)
397 : #endif
398 :
399 : /*
400 : * unlike current_pt_regs(), this one is equal to task_pt_regs(current)
401 : * on *all* architectures; the only reason to have a per-arch definition
402 : * is optimisation.
403 : */
404 : #ifndef signal_pt_regs
405 : #define signal_pt_regs() task_pt_regs(current)
406 : #endif
407 :
408 : #ifndef current_user_stack_pointer
409 : #define current_user_stack_pointer() user_stack_pointer(current_pt_regs())
410 : #endif
411 :
412 : extern int task_current_syscall(struct task_struct *target, struct syscall_info *info);
413 :
414 : extern void sigaction_compat_abi(struct k_sigaction *act, struct k_sigaction *oact);
415 :
416 : /*
417 : * ptrace report for syscall entry and exit looks identical.
418 : */
419 0 : static inline int ptrace_report_syscall(unsigned long message)
420 : {
421 0 : int ptrace = current->ptrace;
422 : int signr;
423 :
424 0 : if (!(ptrace & PT_PTRACED))
425 : return 0;
426 :
427 0 : signr = ptrace_notify(SIGTRAP | ((ptrace & PT_TRACESYSGOOD) ? 0x80 : 0),
428 : message);
429 :
430 : /*
431 : * this isn't the same as continuing with a signal, but it will do
432 : * for normal use. strace only continues with a signal if the
433 : * stopping signal is not SIGTRAP. -brl
434 : */
435 0 : if (signr)
436 0 : send_sig(signr, current, 1);
437 :
438 0 : return fatal_signal_pending(current);
439 : }
440 :
441 : /**
442 : * ptrace_report_syscall_entry - task is about to attempt a system call
443 : * @regs: user register state of current task
444 : *
445 : * This will be called if %SYSCALL_WORK_SYSCALL_TRACE or
446 : * %SYSCALL_WORK_SYSCALL_EMU have been set, when the current task has just
447 : * entered the kernel for a system call. Full user register state is
448 : * available here. Changing the values in @regs can affect the system
449 : * call number and arguments to be tried. It is safe to block here,
450 : * preventing the system call from beginning.
451 : *
452 : * Returns zero normally, or nonzero if the calling arch code should abort
453 : * the system call. That must prevent normal entry so no system call is
454 : * made. If @task ever returns to user mode after this, its register state
455 : * is unspecified, but should be something harmless like an %ENOSYS error
456 : * return. It should preserve enough information so that syscall_rollback()
457 : * can work (see asm-generic/syscall.h).
458 : *
459 : * Called without locks, just after entering kernel mode.
460 : */
461 : static inline __must_check int ptrace_report_syscall_entry(
462 : struct pt_regs *regs)
463 : {
464 0 : return ptrace_report_syscall(PTRACE_EVENTMSG_SYSCALL_ENTRY);
465 : }
466 :
467 : /**
468 : * ptrace_report_syscall_exit - task has just finished a system call
469 : * @regs: user register state of current task
470 : * @step: nonzero if simulating single-step or block-step
471 : *
472 : * This will be called if %SYSCALL_WORK_SYSCALL_TRACE has been set, when
473 : * the current task has just finished an attempted system call. Full
474 : * user register state is available here. It is safe to block here,
475 : * preventing signals from being processed.
476 : *
477 : * If @step is nonzero, this report is also in lieu of the normal
478 : * trap that would follow the system call instruction because
479 : * user_enable_block_step() or user_enable_single_step() was used.
480 : * In this case, %SYSCALL_WORK_SYSCALL_TRACE might not be set.
481 : *
482 : * Called without locks, just before checking for pending signals.
483 : */
484 : static inline void ptrace_report_syscall_exit(struct pt_regs *regs, int step)
485 : {
486 : if (step)
487 : user_single_step_report(regs);
488 : else
489 0 : ptrace_report_syscall(PTRACE_EVENTMSG_SYSCALL_EXIT);
490 : }
491 : #endif
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