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
13 extern int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,
14 void *buf, int len, unsigned int gup_flags);
15
16 /*
17 * Ptrace flags
18 *
19 * The owner ship rules for task->ptrace which holds the ptrace
20 * flags is simple. When a task is running it owns it's task->ptrace
21 * flags. When the a task is stopped the ptracer owns task->ptrace.
22 */
23
24 #define PT_SEIZED 0x00010000 /* SEIZE used, enable new behavior */
25 #define PT_PTRACED 0x00000001
26 #define PT_DTRACE 0x00000002 /* delayed trace (used on m68k, i386) */
27
28 #define PT_OPT_FLAG_SHIFT 3
29 /* PT_TRACE_* event enable flags */
30 #define PT_EVENT_FLAG(event) (1 << (PT_OPT_FLAG_SHIFT + (event)))
31 #define PT_TRACESYSGOOD PT_EVENT_FLAG(0)
32 #define PT_TRACE_FORK PT_EVENT_FLAG(PTRACE_EVENT_FORK)
33 #define PT_TRACE_VFORK PT_EVENT_FLAG(PTRACE_EVENT_VFORK)
34 #define PT_TRACE_CLONE PT_EVENT_FLAG(PTRACE_EVENT_CLONE)
35 #define PT_TRACE_EXEC PT_EVENT_FLAG(PTRACE_EVENT_EXEC)
36 #define PT_TRACE_VFORK_DONE PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE)
37 #define PT_TRACE_EXIT PT_EVENT_FLAG(PTRACE_EVENT_EXIT)
38 #define PT_TRACE_SECCOMP PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP)
39
40 #define PT_EXITKILL (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
41 #define PT_SUSPEND_SECCOMP (PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT)
42
43 extern long arch_ptrace(struct task_struct *child, long request,
44 unsigned long addr, unsigned long data);
45 extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);
46 extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len);
47 extern void ptrace_disable(struct task_struct *);
48 extern int ptrace_request(struct task_struct *child, long request,
49 unsigned long addr, unsigned long data);
50 extern void ptrace_notify(int exit_code);
51 extern void __ptrace_link(struct task_struct *child,
52 struct task_struct *new_parent,
53 const struct cred *ptracer_cred);
54 extern void __ptrace_unlink(struct task_struct *child);
55 extern void exit_ptrace(struct task_struct *tracer, struct list_head *dead);
56 #define PTRACE_MODE_READ 0x01
57 #define PTRACE_MODE_ATTACH 0x02
58 #define PTRACE_MODE_NOAUDIT 0x04
59 #define PTRACE_MODE_FSCREDS 0x08
60 #define PTRACE_MODE_REALCREDS 0x10
61
62 /* shorthands for READ/ATTACH and FSCREDS/REALCREDS combinations */
63 #define PTRACE_MODE_READ_FSCREDS (PTRACE_MODE_READ | PTRACE_MODE_FSCREDS)
64 #define PTRACE_MODE_READ_REALCREDS (PTRACE_MODE_READ | PTRACE_MODE_REALCREDS)
65 #define PTRACE_MODE_ATTACH_FSCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_FSCREDS)
66 #define PTRACE_MODE_ATTACH_REALCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_REALCREDS)
67
68 /**
69 * ptrace_may_access - check whether the caller is permitted to access
70 * a target task.
71 * @task: target task
72 * @mode: selects type of access and caller credentials
73 *
74 * Returns true on success, false on denial.
75 *
76 * One of the flags PTRACE_MODE_FSCREDS and PTRACE_MODE_REALCREDS must
77 * be set in @mode to specify whether the access was requested through
78 * a filesystem syscall (should use effective capabilities and fsuid
79 * of the caller) or through an explicit syscall such as
80 * process_vm_writev or ptrace (and should use the real credentials).
81 */
82 extern bool ptrace_may_access(struct task_struct *task, unsigned int mode);
83
ptrace_reparented(struct task_struct * child)84 static inline int ptrace_reparented(struct task_struct *child)
85 {
86 return !same_thread_group(child->real_parent, child->parent);
87 }
88
ptrace_unlink(struct task_struct * child)89 static inline void ptrace_unlink(struct task_struct *child)
90 {
91 if (unlikely(child->ptrace))
92 __ptrace_unlink(child);
93 }
94
95 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
96 unsigned long data);
97 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
98 unsigned long data);
99
100 /**
101 * ptrace_parent - return the task that is tracing the given task
102 * @task: task to consider
103 *
104 * Returns %NULL if no one is tracing @task, or the &struct task_struct
105 * pointer to its tracer.
106 *
107 * Must called under rcu_read_lock(). The pointer returned might be kept
108 * live only by RCU. During exec, this may be called with task_lock() held
109 * on @task, still held from when check_unsafe_exec() was called.
110 */
ptrace_parent(struct task_struct * task)111 static inline struct task_struct *ptrace_parent(struct task_struct *task)
112 {
113 if (unlikely(task->ptrace))
114 return rcu_dereference(task->parent);
115 return NULL;
116 }
117
118 /**
119 * ptrace_event_enabled - test whether a ptrace event is enabled
120 * @task: ptracee of interest
121 * @event: %PTRACE_EVENT_* to test
122 *
123 * Test whether @event is enabled for ptracee @task.
124 *
125 * Returns %true if @event is enabled, %false otherwise.
126 */
ptrace_event_enabled(struct task_struct * task,int event)127 static inline bool ptrace_event_enabled(struct task_struct *task, int event)
128 {
129 return task->ptrace & PT_EVENT_FLAG(event);
130 }
131
132 /**
133 * ptrace_event - possibly stop for a ptrace event notification
134 * @event: %PTRACE_EVENT_* value to report
135 * @message: value for %PTRACE_GETEVENTMSG to return
136 *
137 * Check whether @event is enabled and, if so, report @event and @message
138 * to the ptrace parent.
139 *
140 * Called without locks.
141 */
ptrace_event(int event,unsigned long message)142 static inline void ptrace_event(int event, unsigned long message)
143 {
144 if (unlikely(ptrace_event_enabled(current, event))) {
145 current->ptrace_message = message;
146 ptrace_notify((event << 8) | SIGTRAP);
147 } else if (event == PTRACE_EVENT_EXEC) {
148 /* legacy EXEC report via SIGTRAP */
149 if ((current->ptrace & (PT_PTRACED|PT_SEIZED)) == PT_PTRACED)
150 send_sig(SIGTRAP, current, 0);
151 }
152 }
153
154 /**
155 * ptrace_event_pid - possibly stop for a ptrace event notification
156 * @event: %PTRACE_EVENT_* value to report
157 * @pid: process identifier for %PTRACE_GETEVENTMSG to return
158 *
159 * Check whether @event is enabled and, if so, report @event and @pid
160 * to the ptrace parent. @pid is reported as the pid_t seen from the
161 * the ptrace parent's pid namespace.
162 *
163 * Called without locks.
164 */
ptrace_event_pid(int event,struct pid * pid)165 static inline void ptrace_event_pid(int event, struct pid *pid)
166 {
167 /*
168 * FIXME: There's a potential race if a ptracer in a different pid
169 * namespace than parent attaches between computing message below and
170 * when we acquire tasklist_lock in ptrace_stop(). If this happens,
171 * the ptracer will get a bogus pid from PTRACE_GETEVENTMSG.
172 */
173 unsigned long message = 0;
174 struct pid_namespace *ns;
175
176 rcu_read_lock();
177 ns = task_active_pid_ns(rcu_dereference(current->parent));
178 if (ns)
179 message = pid_nr_ns(pid, ns);
180 rcu_read_unlock();
181
182 ptrace_event(event, message);
183 }
184
185 /**
186 * ptrace_init_task - initialize ptrace state for a new child
187 * @child: new child task
188 * @ptrace: true if child should be ptrace'd by parent's tracer
189 *
190 * This is called immediately after adding @child to its parent's children
191 * list. @ptrace is false in the normal case, and true to ptrace @child.
192 *
193 * Called with current's siglock and write_lock_irq(&tasklist_lock) held.
194 */
ptrace_init_task(struct task_struct * child,bool ptrace)195 static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
196 {
197 INIT_LIST_HEAD(&child->ptrace_entry);
198 INIT_LIST_HEAD(&child->ptraced);
199 child->jobctl = 0;
200 child->ptrace = 0;
201 child->parent = child->real_parent;
202
203 if (unlikely(ptrace) && current->ptrace) {
204 child->ptrace = current->ptrace;
205 __ptrace_link(child, current->parent, current->ptracer_cred);
206
207 if (child->ptrace & PT_SEIZED)
208 task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
209 else
210 sigaddset(&child->pending.signal, SIGSTOP);
211 }
212 else
213 child->ptracer_cred = NULL;
214 }
215
216 /**
217 * ptrace_release_task - final ptrace-related cleanup of a zombie being reaped
218 * @task: task in %EXIT_DEAD state
219 *
220 * Called with write_lock(&tasklist_lock) held.
221 */
ptrace_release_task(struct task_struct * task)222 static inline void ptrace_release_task(struct task_struct *task)
223 {
224 BUG_ON(!list_empty(&task->ptraced));
225 ptrace_unlink(task);
226 BUG_ON(!list_empty(&task->ptrace_entry));
227 }
228
229 #ifndef force_successful_syscall_return
230 /*
231 * System call handlers that, upon successful completion, need to return a
232 * negative value should call force_successful_syscall_return() right before
233 * returning. On architectures where the syscall convention provides for a
234 * separate error flag (e.g., alpha, ia64, ppc{,64}, sparc{,64}, possibly
235 * others), this macro can be used to ensure that the error flag will not get
236 * set. On architectures which do not support a separate error flag, the macro
237 * is a no-op and the spurious error condition needs to be filtered out by some
238 * other means (e.g., in user-level, by passing an extra argument to the
239 * syscall handler, or something along those lines).
240 */
241 #define force_successful_syscall_return() do { } while (0)
242 #endif
243
244 #ifndef is_syscall_success
245 /*
246 * On most systems we can tell if a syscall is a success based on if the retval
247 * is an error value. On some systems like ia64 and powerpc they have different
248 * indicators of success/failure and must define their own.
249 */
250 #define is_syscall_success(regs) (!IS_ERR_VALUE((unsigned long)(regs_return_value(regs))))
251 #endif
252
253 /*
254 * <asm/ptrace.h> should define the following things inside #ifdef __KERNEL__.
255 *
256 * These do-nothing inlines are used when the arch does not
257 * implement single-step. The kerneldoc comments are here
258 * to document the interface for all arch definitions.
259 */
260
261 #ifndef arch_has_single_step
262 /**
263 * arch_has_single_step - does this CPU support user-mode single-step?
264 *
265 * If this is defined, then there must be function declarations or
266 * inlines for user_enable_single_step() and user_disable_single_step().
267 * arch_has_single_step() should evaluate to nonzero iff the machine
268 * supports instruction single-step for user mode.
269 * It can be a constant or it can test a CPU feature bit.
270 */
271 #define arch_has_single_step() (0)
272
273 /**
274 * user_enable_single_step - single-step in user-mode task
275 * @task: either current or a task stopped in %TASK_TRACED
276 *
277 * This can only be called when arch_has_single_step() has returned nonzero.
278 * Set @task so that when it returns to user mode, it will trap after the
279 * next single instruction executes. If arch_has_block_step() is defined,
280 * this must clear the effects of user_enable_block_step() too.
281 */
user_enable_single_step(struct task_struct * task)282 static inline void user_enable_single_step(struct task_struct *task)
283 {
284 BUG(); /* This can never be called. */
285 }
286
287 /**
288 * user_disable_single_step - cancel user-mode single-step
289 * @task: either current or a task stopped in %TASK_TRACED
290 *
291 * Clear @task of the effects of user_enable_single_step() and
292 * user_enable_block_step(). This can be called whether or not either
293 * of those was ever called on @task, and even if arch_has_single_step()
294 * returned zero.
295 */
user_disable_single_step(struct task_struct * task)296 static inline void user_disable_single_step(struct task_struct *task)
297 {
298 }
299 #else
300 extern void user_enable_single_step(struct task_struct *);
301 extern void user_disable_single_step(struct task_struct *);
302 #endif /* arch_has_single_step */
303
304 #ifndef arch_has_block_step
305 /**
306 * arch_has_block_step - does this CPU support user-mode block-step?
307 *
308 * If this is defined, then there must be a function declaration or inline
309 * for user_enable_block_step(), and arch_has_single_step() must be defined
310 * too. arch_has_block_step() should evaluate to nonzero iff the machine
311 * supports step-until-branch for user mode. It can be a constant or it
312 * can test a CPU feature bit.
313 */
314 #define arch_has_block_step() (0)
315
316 /**
317 * user_enable_block_step - step until branch in user-mode task
318 * @task: either current or a task stopped in %TASK_TRACED
319 *
320 * This can only be called when arch_has_block_step() has returned nonzero,
321 * and will never be called when single-instruction stepping is being used.
322 * Set @task so that when it returns to user mode, it will trap after the
323 * next branch or trap taken.
324 */
user_enable_block_step(struct task_struct * task)325 static inline void user_enable_block_step(struct task_struct *task)
326 {
327 BUG(); /* This can never be called. */
328 }
329 #else
330 extern void user_enable_block_step(struct task_struct *);
331 #endif /* arch_has_block_step */
332
333 #ifdef ARCH_HAS_USER_SINGLE_STEP_INFO
334 extern void user_single_step_siginfo(struct task_struct *tsk,
335 struct pt_regs *regs, siginfo_t *info);
336 #else
user_single_step_siginfo(struct task_struct * tsk,struct pt_regs * regs,siginfo_t * info)337 static inline void user_single_step_siginfo(struct task_struct *tsk,
338 struct pt_regs *regs, siginfo_t *info)
339 {
340 info->si_signo = SIGTRAP;
341 }
342 #endif
343
344 #ifndef arch_ptrace_stop_needed
345 /**
346 * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
347 * @code: current->exit_code value ptrace will stop with
348 * @info: siginfo_t pointer (or %NULL) for signal ptrace will stop with
349 *
350 * This is called with the siglock held, to decide whether or not it's
351 * necessary to release the siglock and call arch_ptrace_stop() with the
352 * same @code and @info arguments. It can be defined to a constant if
353 * arch_ptrace_stop() is never required, or always is. On machines where
354 * this makes sense, it should be defined to a quick test to optimize out
355 * calling arch_ptrace_stop() when it would be superfluous. For example,
356 * if the thread has not been back to user mode since the last stop, the
357 * thread state might indicate that nothing needs to be done.
358 *
359 * This is guaranteed to be invoked once before a task stops for ptrace and
360 * may include arch-specific operations necessary prior to a ptrace stop.
361 */
362 #define arch_ptrace_stop_needed(code, info) (0)
363 #endif
364
365 #ifndef arch_ptrace_stop
366 /**
367 * arch_ptrace_stop - Do machine-specific work before stopping for ptrace
368 * @code: current->exit_code value ptrace will stop with
369 * @info: siginfo_t pointer (or %NULL) for signal ptrace will stop with
370 *
371 * This is called with no locks held when arch_ptrace_stop_needed() has
372 * just returned nonzero. It is allowed to block, e.g. for user memory
373 * access. The arch can have machine-specific work to be done before
374 * ptrace stops. On ia64, register backing store gets written back to user
375 * memory here. Since this can be costly (requires dropping the siglock),
376 * we only do it when the arch requires it for this particular stop, as
377 * indicated by arch_ptrace_stop_needed().
378 */
379 #define arch_ptrace_stop(code, info) do { } while (0)
380 #endif
381
382 #ifndef current_pt_regs
383 #define current_pt_regs() task_pt_regs(current)
384 #endif
385
386 /*
387 * unlike current_pt_regs(), this one is equal to task_pt_regs(current)
388 * on *all* architectures; the only reason to have a per-arch definition
389 * is optimisation.
390 */
391 #ifndef signal_pt_regs
392 #define signal_pt_regs() task_pt_regs(current)
393 #endif
394
395 #ifndef current_user_stack_pointer
396 #define current_user_stack_pointer() user_stack_pointer(current_pt_regs())
397 #endif
398
399 extern int task_current_syscall(struct task_struct *target, long *callno,
400 unsigned long args[6], unsigned int maxargs,
401 unsigned long *sp, unsigned long *pc);
402
403 #endif
404