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 return !same_thread_group(child->real_parent, child->parent);
93 }
94
95 static inline void ptrace_unlink(struct task_struct *child)
96 {
97 if (unlikely(child->ptrace))
98 __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 if (unlikely(task->ptrace))
120 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 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 static inline void ptrace_event(int event, unsigned long message)
149 {
150 if (unlikely(ptrace_event_enabled(current, event))) {
151 ptrace_notify((event << 8) | SIGTRAP, message);
152 } else if (event == PTRACE_EVENT_EXEC) {
153 /* legacy EXEC report via SIGTRAP */
154 if ((current->ptrace & (PT_PTRACED|PT_SEIZED)) == PT_PTRACED)
155 send_sig(SIGTRAP, current, 0);
156 }
157 }
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 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 unsigned long message = 0;
179 struct pid_namespace *ns;
180
181 rcu_read_lock();
182 ns = task_active_pid_ns(rcu_dereference(current->parent));
183 if (ns)
184 message = pid_nr_ns(pid, ns);
185 rcu_read_unlock();
186
187 ptrace_event(event, message);
188 }
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 static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
201 {
202 INIT_LIST_HEAD(&child->ptrace_entry);
203 INIT_LIST_HEAD(&child->ptraced);
204 child->jobctl = 0;
205 child->ptrace = 0;
206 child->parent = child->real_parent;
207
208 if (unlikely(ptrace) && current->ptrace) {
209 child->ptrace = current->ptrace;
210 __ptrace_link(child, current->parent, current->ptracer_cred);
211
212 if (child->ptrace & PT_SEIZED)
213 task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
214 else
215 sigaddset(&child->pending.signal, SIGSTOP);
216 }
217 else
218 child->ptracer_cred = NULL;
219 }
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 static inline void ptrace_release_task(struct task_struct *task)
228 {
229 BUG_ON(!list_empty(&task->ptraced));
230 ptrace_unlink(task);
231 BUG_ON(!list_empty(&task->ptrace_entry));
232 }
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 #ifndef exception_ip
397 #define exception_ip(x) instruction_pointer(x)
398 #endif
399
400 extern int task_current_syscall(struct task_struct *target, struct syscall_info *info);
401
402 extern void sigaction_compat_abi(struct k_sigaction *act, struct k_sigaction *oact);
403
404 /*
405 * ptrace report for syscall entry and exit looks identical.
406 */
407 static inline int ptrace_report_syscall(unsigned long message)
408 {
409 int ptrace = current->ptrace;
410 int signr;
411
412 if (!(ptrace & PT_PTRACED))
413 return 0;
414
415 signr = ptrace_notify(SIGTRAP | ((ptrace & PT_TRACESYSGOOD) ? 0x80 : 0),
416 message);
417
418 /*
419 * this isn't the same as continuing with a signal, but it will do
420 * for normal use. strace only continues with a signal if the
421 * stopping signal is not SIGTRAP. -brl
422 */
423 if (signr)
424 send_sig(signr, current, 1);
425
426 return fatal_signal_pending(current);
427 }
428
429 /**
430 * ptrace_report_syscall_entry - task is about to attempt a system call
431 * @regs: user register state of current task
432 *
433 * This will be called if %SYSCALL_WORK_SYSCALL_TRACE or
434 * %SYSCALL_WORK_SYSCALL_EMU have been set, when the current task has just
435 * entered the kernel for a system call. Full user register state is
436 * available here. Changing the values in @regs can affect the system
437 * call number and arguments to be tried. It is safe to block here,
438 * preventing the system call from beginning.
439 *
440 * Returns zero normally, or nonzero if the calling arch code should abort
441 * the system call. That must prevent normal entry so no system call is
442 * made. If @task ever returns to user mode after this, its register state
443 * is unspecified, but should be something harmless like an %ENOSYS error
444 * return. It should preserve enough information so that syscall_rollback()
445 * can work (see asm-generic/syscall.h).
446 *
447 * Called without locks, just after entering kernel mode.
448 */
449 static inline __must_check int ptrace_report_syscall_entry(
450 struct pt_regs *regs)
451 {
452 return ptrace_report_syscall(PTRACE_EVENTMSG_SYSCALL_ENTRY);
453 }
454
455 /**
456 * ptrace_report_syscall_exit - task has just finished a system call
457 * @regs: user register state of current task
458 * @step: nonzero if simulating single-step or block-step
459 *
460 * This will be called if %SYSCALL_WORK_SYSCALL_TRACE has been set, when
461 * the current task has just finished an attempted system call. Full
462 * user register state is available here. It is safe to block here,
463 * preventing signals from being processed.
464 *
465 * If @step is nonzero, this report is also in lieu of the normal
466 * trap that would follow the system call instruction because
467 * user_enable_block_step() or user_enable_single_step() was used.
468 * In this case, %SYSCALL_WORK_SYSCALL_TRACE might not be set.
469 *
470 * Called without locks, just before checking for pending signals.
471 */
472 static inline void ptrace_report_syscall_exit(struct pt_regs *regs, int step)
473 {
474 if (step)
475 user_single_step_report(regs);
476 else
477 ptrace_report_syscall(PTRACE_EVENTMSG_SYSCALL_EXIT);
478 }
479 #endif
480
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