summaryrefslogtreecommitdiff
path: root/include/linux/ptrace.h
blob: 90507d4afcd6debb80eef494c4c874c8a1732e49 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_PTRACE_H
#define _LINUX_PTRACE_H

#include <linux/compiler.h>		/* For unlikely.  */
#include <linux/sched.h>		/* For struct task_struct.  */
#include <linux/sched/signal.h>		/* For send_sig(), same_thread_group(), etc. */
#include <linux/err.h>			/* for IS_ERR_VALUE */
#include <linux/bug.h>			/* For BUG_ON.  */
#include <linux/pid_namespace.h>	/* For task_active_pid_ns.  */
#include <uapi/linux/ptrace.h>
#include <linux/seccomp.h>

/* Add sp to seccomp_data, as seccomp is user API, we don't want to modify it */
struct syscall_info {
	__u64			sp;
	struct seccomp_data	data;
};

extern int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,
			    void *buf, int len, unsigned int gup_flags);

/*
 * Ptrace flags
 *
 * The owner ship rules for task->ptrace which holds the ptrace
 * flags is simple.  When a task is running it owns it's task->ptrace
 * flags.  When the a task is stopped the ptracer owns task->ptrace.
 */

#define PT_SEIZED	0x00010000	/* SEIZE used, enable new behavior */
#define PT_PTRACED	0x00000001

#define PT_OPT_FLAG_SHIFT	3
/* PT_TRACE_* event enable flags */
#define PT_EVENT_FLAG(event)	(1 << (PT_OPT_FLAG_SHIFT + (event)))
#define PT_TRACESYSGOOD		PT_EVENT_FLAG(0)
#define PT_TRACE_FORK		PT_EVENT_FLAG(PTRACE_EVENT_FORK)
#define PT_TRACE_VFORK		PT_EVENT_FLAG(PTRACE_EVENT_VFORK)
#define PT_TRACE_CLONE		PT_EVENT_FLAG(PTRACE_EVENT_CLONE)
#define PT_TRACE_EXEC		PT_EVENT_FLAG(PTRACE_EVENT_EXEC)
#define PT_TRACE_VFORK_DONE	PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE)
#define PT_TRACE_EXIT		PT_EVENT_FLAG(PTRACE_EVENT_EXIT)
#define PT_TRACE_SECCOMP	PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP)

#define PT_EXITKILL		(PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
#define PT_SUSPEND_SECCOMP	(PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT)

extern long arch_ptrace(struct task_struct *child, long request,
			unsigned long addr, unsigned long data);
extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);
extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len);
extern void ptrace_disable(struct task_struct *);
extern int ptrace_request(struct task_struct *child, long request,
			  unsigned long addr, unsigned long data);
extern int ptrace_notify(int exit_code, unsigned long message);
extern void __ptrace_link(struct task_struct *child,
			  struct task_struct *new_parent,
			  const struct cred *ptracer_cred);
extern void __ptrace_unlink(struct task_struct *child);
extern void exit_ptrace(struct task_struct *tracer, struct list_head *dead);
#define PTRACE_MODE_READ	0x01
#define PTRACE_MODE_ATTACH	0x02
#define PTRACE_MODE_NOAUDIT	0x04
#define PTRACE_MODE_FSCREDS	0x08
#define PTRACE_MODE_REALCREDS	0x10

/* shorthands for READ/ATTACH and FSCREDS/REALCREDS combinations */
#define PTRACE_MODE_READ_FSCREDS (PTRACE_MODE_READ | PTRACE_MODE_FSCREDS)
#define PTRACE_MODE_READ_REALCREDS (PTRACE_MODE_READ | PTRACE_MODE_REALCREDS)
#define PTRACE_MODE_ATTACH_FSCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_FSCREDS)
#define PTRACE_MODE_ATTACH_REALCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_REALCREDS)

/**
 * ptrace_may_access - check whether the caller is permitted to access
 * a target task.
 * @task: target task
 * @mode: selects type of access and caller credentials
 *
 * Returns true on success, false on denial.
 *
 * One of the flags PTRACE_MODE_FSCREDS and PTRACE_MODE_REALCREDS must
 * be set in @mode to specify whether the access was requested through
 * a filesystem syscall (should use effective capabilities and fsuid
 * of the caller) or through an explicit syscall such as
 * process_vm_writev or ptrace (and should use the real credentials).
 */
extern bool ptrace_may_access(struct task_struct *task, unsigned int mode);

static inline int ptrace_reparented(struct task_struct *child)
{
	return !same_thread_group(child->real_parent, child->parent);
}

static inline void ptrace_unlink(struct task_struct *child)
{
	if (unlikely(child->ptrace))
		__ptrace_unlink(child);
}

int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
			    unsigned long data);
int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
			    unsigned long data);

/**
 * ptrace_parent - return the task that is tracing the given task
 * @task: task to consider
 *
 * Returns %NULL if no one is tracing @task, or the &struct task_struct
 * pointer to its tracer.
 *
 * Must called under rcu_read_lock().  The pointer returned might be kept
 * live only by RCU.  During exec, this may be called with task_lock() held
 * on @task, still held from when check_unsafe_exec() was called.
 */
static inline struct task_struct *ptrace_parent(struct task_struct *task)
{
	if (unlikely(task->ptrace))
		return rcu_dereference(task->parent);
	return NULL;
}

/**
 * ptrace_event_enabled - test whether a ptrace event is enabled
 * @task: ptracee of interest
 * @event: %PTRACE_EVENT_* to test
 *
 * Test whether @event is enabled for ptracee @task.
 *
 * Returns %true if @event is enabled, %false otherwise.
 */
static inline bool ptrace_event_enabled(struct task_struct *task, int event)
{
	return task->ptrace & PT_EVENT_FLAG(event);
}

/**
 * ptrace_event - possibly stop for a ptrace event notification
 * @event:	%PTRACE_EVENT_* value to report
 * @message:	value for %PTRACE_GETEVENTMSG to return
 *
 * Check whether @event is enabled and, if so, report @event and @message
 * to the ptrace parent.
 *
 * Called without locks.
 */
static inline void ptrace_event(int event, unsigned long message)
{
	if (unlikely(ptrace_event_enabled(current, event))) {
		ptrace_notify((event << 8) | SIGTRAP, message);
	} else if (event == PTRACE_EVENT_EXEC) {
		/* legacy EXEC report via SIGTRAP */
		if ((current->ptrace & (PT_PTRACED|PT_SEIZED)) == PT_PTRACED)
			send_sig(SIGTRAP, current, 0);
	}
}

/**
 * ptrace_event_pid - possibly stop for a ptrace event notification
 * @event:	%PTRACE_EVENT_* value to report
 * @pid:	process identifier for %PTRACE_GETEVENTMSG to return
 *
 * Check whether @event is enabled and, if so, report @event and @pid
 * to the ptrace parent.  @pid is reported as the pid_t seen from the
 * ptrace parent's pid namespace.
 *
 * Called without locks.
 */
static inline void ptrace_event_pid(int event, struct pid *pid)
{
	/*
	 * FIXME: There's a potential race if a ptracer in a different pid
	 * namespace than parent attaches between computing message below and
	 * when we acquire tasklist_lock in ptrace_stop().  If this happens,
	 * the ptracer will get a bogus pid from PTRACE_GETEVENTMSG.
	 */
	unsigned long message = 0;
	struct pid_namespace *ns;

	rcu_read_lock();
	ns = task_active_pid_ns(rcu_dereference(current->parent));
	if (ns)
		message = pid_nr_ns(pid, ns);
	rcu_read_unlock();

	ptrace_event(event, message);
}

/**
 * ptrace_init_task - initialize ptrace state for a new child
 * @child:		new child task
 * @ptrace:		true if child should be ptrace'd by parent's tracer
 *
 * This is called immediately after adding @child to its parent's children
 * list.  @ptrace is false in the normal case, and true to ptrace @child.
 *
 * Called with current's siglock and write_lock_irq(&tasklist_lock) held.
 */
static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
{
	INIT_LIST_HEAD(&child->ptrace_entry);
	INIT_LIST_HEAD(&child->ptraced);
	child->jobctl = 0;
	child->ptrace = 0;
	child->parent = child->real_parent;

	if (unlikely(ptrace) && current->ptrace) {
		child->ptrace = current->ptrace;
		__ptrace_link(child, current->parent, current->ptracer_cred);

		if (child->ptrace & PT_SEIZED)
			task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
		else
			sigaddset(&child->pending.signal, SIGSTOP);
	}
	else
		child->ptracer_cred = NULL;
}

/**
 * ptrace_release_task - final ptrace-related cleanup of a zombie being reaped
 * @task:	task in %EXIT_DEAD state
 *
 * Called with write_lock(&tasklist_lock) held.
 */
static inline void ptrace_release_task(struct task_struct *task)
{
	BUG_ON(!list_empty(&task->ptraced));
	ptrace_unlink(task);
	BUG_ON(!list_empty(&task->ptrace_entry));
}

#ifndef force_successful_syscall_return
/*
 * System call handlers that, upon successful completion, need to return a
 * negative value should call force_successful_syscall_return() right before
 * returning.  On architectures where the syscall convention provides for a
 * separate error flag (e.g., alpha, ia64, ppc{,64}, sparc{,64}, possibly
 * others), this macro can be used to ensure that the error flag will not get
 * set.  On architectures which do not support a separate error flag, the macro
 * is a no-op and the spurious error condition needs to be filtered out by some
 * other means (e.g., in user-level, by passing an extra argument to the
 * syscall handler, or something along those lines).
 */
#define force_successful_syscall_return() do { } while (0)
#endif

#ifndef is_syscall_success
/*
 * On most systems we can tell if a syscall is a success based on if the retval
 * is an error value.  On some systems like ia64 and powerpc they have different
 * indicators of success/failure and must define their own.
 */
#define is_syscall_success(regs) (!IS_ERR_VALUE((unsigned long)(regs_return_value(regs))))
#endif

/*
 * <asm/ptrace.h> should define the following things inside #ifdef __KERNEL__.
 *
 * These do-nothing inlines are used when the arch does not
 * implement single-step.  The kerneldoc comments are here
 * to document the interface for all arch definitions.
 */

#ifndef arch_has_single_step
/**
 * arch_has_single_step - does this CPU support user-mode single-step?
 *
 * If this is defined, then there must be function declarations or
 * inlines for user_enable_single_step() and user_disable_single_step().
 * arch_has_single_step() should evaluate to nonzero iff the machine
 * supports instruction single-step for user mode.
 * It can be a constant or it can test a CPU feature bit.
 */
#define arch_has_single_step()		(0)

/**
 * user_enable_single_step - single-step in user-mode task
 * @task: either current or a task stopped in %TASK_TRACED
 *
 * This can only be called when arch_has_single_step() has returned nonzero.
 * Set @task so that when it returns to user mode, it will trap after the
 * next single instruction executes.  If arch_has_block_step() is defined,
 * this must clear the effects of user_enable_block_step() too.
 */
static inline void user_enable_single_step(struct task_struct *task)
{
	BUG();			/* This can never be called.  */
}

/**
 * user_disable_single_step - cancel user-mode single-step
 * @task: either current or a task stopped in %TASK_TRACED
 *
 * Clear @task of the effects of user_enable_single_step() and
 * user_enable_block_step().  This can be called whether or not either
 * of those was ever called on @task, and even if arch_has_single_step()
 * returned zero.
 */
static inline void user_disable_single_step(struct task_struct *task)
{
}
#else
extern void user_enable_single_step(struct task_struct *);
extern void user_disable_single_step(struct task_struct *);
#endif	/* arch_has_single_step */

#ifndef arch_has_block_step
/**
 * arch_has_block_step - does this CPU support user-mode block-step?
 *
 * If this is defined, then there must be a function declaration or inline
 * for user_enable_block_step(), and arch_has_single_step() must be defined
 * too.  arch_has_block_step() should evaluate to nonzero iff the machine
 * supports step-until-branch for user mode.  It can be a constant or it
 * can test a CPU feature bit.
 */
#define arch_has_block_step()		(0)

/**
 * user_enable_block_step - step until branch in user-mode task
 * @task: either current or a task stopped in %TASK_TRACED
 *
 * This can only be called when arch_has_block_step() has returned nonzero,
 * and will never be called when single-instruction stepping is being used.
 * Set @task so that when it returns to user mode, it will trap after the
 * next branch or trap taken.
 */
static inline void user_enable_block_step(struct task_struct *task)
{
	BUG();			/* This can never be called.  */
}
#else
extern void user_enable_block_step(struct task_struct *);
#endif	/* arch_has_block_step */

#ifdef ARCH_HAS_USER_SINGLE_STEP_REPORT
extern void user_single_step_report(struct pt_regs *regs);
#else
static inline void user_single_step_report(struct pt_regs *regs)
{
	kernel_siginfo_t info;
	clear_siginfo(&info);
	info.si_signo = SIGTRAP;
	info.si_errno = 0;
	info.si_code = SI_USER;
	info.si_pid = 0;
	info.si_uid = 0;
	force_sig_info(&info);
}
#endif

#ifndef arch_ptrace_stop_needed
/**
 * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
 *
 * This is called with the siglock held, to decide whether or not it's
 * necessary to release the siglock and call arch_ptrace_stop().  It can be
 * defined to a constant if arch_ptrace_stop() is never required, or always
 * is.  On machines where this makes sense, it should be defined to a quick
 * test to optimize out calling arch_ptrace_stop() when it would be
 * superfluous.  For example, if the thread has not been back to user mode
 * since the last stop, the thread state might indicate that nothing needs
 * to be done.
 *
 * This is guaranteed to be invoked once before a task stops for ptrace and
 * may include arch-specific operations necessary prior to a ptrace stop.
 */
#define arch_ptrace_stop_needed()	(0)
#endif

#ifndef arch_ptrace_stop
/**
 * arch_ptrace_stop - Do machine-specific work before stopping for ptrace
 *
 * This is called with no locks held when arch_ptrace_stop_needed() has
 * just returned nonzero.  It is allowed to block, e.g. for user memory
 * access.  The arch can have machine-specific work to be done before
 * ptrace stops.  On ia64, register backing store gets written back to user
 * memory here.  Since this can be costly (requires dropping the siglock),
 * we only do it when the arch requires it for this particular stop, as
 * indicated by arch_ptrace_stop_needed().
 */
#define arch_ptrace_stop()		do { } while (0)
#endif

#ifndef current_pt_regs
#define current_pt_regs() task_pt_regs(current)
#endif

#ifndef current_user_stack_pointer
#define current_user_stack_pointer() user_stack_pointer(current_pt_regs())
#endif

#ifndef exception_ip
#define exception_ip(x) instruction_pointer(x)
#endif

extern int task_current_syscall(struct task_struct *target, struct syscall_info *info);

extern void sigaction_compat_abi(struct k_sigaction *act, struct k_sigaction *oact);

/*
 * ptrace report for syscall entry and exit looks identical.
 */
static inline int ptrace_report_syscall(unsigned long message)
{
	int ptrace = current->ptrace;
	int signr;

	if (!(ptrace & PT_PTRACED))
		return 0;

	signr = ptrace_notify(SIGTRAP | ((ptrace & PT_TRACESYSGOOD) ? 0x80 : 0),
			      message);

	/*
	 * this isn't the same as continuing with a signal, but it will do
	 * for normal use.  strace only continues with a signal if the
	 * stopping signal is not SIGTRAP.  -brl
	 */
	if (signr)
		send_sig(signr, current, 1);

	return fatal_signal_pending(current);
}

/**
 * ptrace_report_syscall_entry - task is about to attempt a system call
 * @regs:		user register state of current task
 *
 * This will be called if %SYSCALL_WORK_SYSCALL_TRACE or
 * %SYSCALL_WORK_SYSCALL_EMU have been set, when the current task has just
 * entered the kernel for a system call.  Full user register state is
 * available here.  Changing the values in @regs can affect the system
 * call number and arguments to be tried.  It is safe to block here,
 * preventing the system call from beginning.
 *
 * Returns zero normally, or nonzero if the calling arch code should abort
 * the system call.  That must prevent normal entry so no system call is
 * made.  If @task ever returns to user mode after this, its register state
 * is unspecified, but should be something harmless like an %ENOSYS error
 * return.  It should preserve enough information so that syscall_rollback()
 * can work (see asm-generic/syscall.h).
 *
 * Called without locks, just after entering kernel mode.
 */
static inline __must_check int ptrace_report_syscall_entry(
	struct pt_regs *regs)
{
	return ptrace_report_syscall(PTRACE_EVENTMSG_SYSCALL_ENTRY);
}

/**
 * ptrace_report_syscall_exit - task has just finished a system call
 * @regs:		user register state of current task
 * @step:		nonzero if simulating single-step or block-step
 *
 * This will be called if %SYSCALL_WORK_SYSCALL_TRACE has been set, when
 * the current task has just finished an attempted system call.  Full
 * user register state is available here.  It is safe to block here,
 * preventing signals from being processed.
 *
 * If @step is nonzero, this report is also in lieu of the normal
 * trap that would follow the system call instruction because
 * user_enable_block_step() or user_enable_single_step() was used.
 * In this case, %SYSCALL_WORK_SYSCALL_TRACE might not be set.
 *
 * Called without locks, just before checking for pending signals.
 */
static inline void ptrace_report_syscall_exit(struct pt_regs *regs, int step)
{
	if (step)
		user_single_step_report(regs);
	else
		ptrace_report_syscall(PTRACE_EVENTMSG_SYSCALL_EXIT);
}
#endif