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TOMOYO Linux Cross Reference
Linux/include/linux/ptrace.h

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  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 void ptrace_notify(int exit_code);
 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         return !same_thread_group(child->real_parent, child->parent);
100 }
101 
102 static inline void ptrace_unlink(struct task_struct *child)
103 {
104         if (unlikely(child->ptrace))
105                 __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         if (unlikely(task->ptrace))
127                 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         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 static inline void ptrace_event(int event, unsigned long message)
156 {
157         if (unlikely(ptrace_event_enabled(current, event))) {
158                 current->ptrace_message = message;
159                 ptrace_notify((event << 8) | SIGTRAP);
160         } else if (event == PTRACE_EVENT_EXEC) {
161                 /* legacy EXEC report via SIGTRAP */
162                 if ((current->ptrace & (PT_PTRACED|PT_SEIZED)) == PT_PTRACED)
163                         send_sig(SIGTRAP, current, 0);
164         }
165 }
166 
167 /**
168  * ptrace_event_pid - possibly stop for a ptrace event notification
169  * @event:      %PTRACE_EVENT_* value to report
170  * @pid:        process identifier for %PTRACE_GETEVENTMSG to return
171  *
172  * Check whether @event is enabled and, if so, report @event and @pid
173  * to the ptrace parent.  @pid is reported as the pid_t seen from the
174  * ptrace parent's pid namespace.
175  *
176  * Called without locks.
177  */
178 static inline void ptrace_event_pid(int event, struct pid *pid)
179 {
180         /*
181          * FIXME: There's a potential race if a ptracer in a different pid
182          * namespace than parent attaches between computing message below and
183          * when we acquire tasklist_lock in ptrace_stop().  If this happens,
184          * the ptracer will get a bogus pid from PTRACE_GETEVENTMSG.
185          */
186         unsigned long message = 0;
187         struct pid_namespace *ns;
188 
189         rcu_read_lock();
190         ns = task_active_pid_ns(rcu_dereference(current->parent));
191         if (ns)
192                 message = pid_nr_ns(pid, ns);
193         rcu_read_unlock();
194 
195         ptrace_event(event, message);
196 }
197 
198 /**
199  * ptrace_init_task - initialize ptrace state for a new child
200  * @child:              new child task
201  * @ptrace:             true if child should be ptrace'd by parent's tracer
202  *
203  * This is called immediately after adding @child to its parent's children
204  * list.  @ptrace is false in the normal case, and true to ptrace @child.
205  *
206  * Called with current's siglock and write_lock_irq(&tasklist_lock) held.
207  */
208 static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
209 {
210         INIT_LIST_HEAD(&child->ptrace_entry);
211         INIT_LIST_HEAD(&child->ptraced);
212         child->jobctl = 0;
213         child->ptrace = 0;
214         child->parent = child->real_parent;
215 
216         if (unlikely(ptrace) && current->ptrace) {
217                 child->ptrace = current->ptrace;
218                 __ptrace_link(child, current->parent, current->ptracer_cred);
219 
220                 if (child->ptrace & PT_SEIZED)
221                         task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
222                 else
223                         sigaddset(&child->pending.signal, SIGSTOP);
224         }
225         else
226                 child->ptracer_cred = NULL;
227 }
228 
229 /**
230  * ptrace_release_task - final ptrace-related cleanup of a zombie being reaped
231  * @task:       task in %EXIT_DEAD state
232  *
233  * Called with write_lock(&tasklist_lock) held.
234  */
235 static inline void ptrace_release_task(struct task_struct *task)
236 {
237         BUG_ON(!list_empty(&task->ptraced));
238         ptrace_unlink(task);
239         BUG_ON(!list_empty(&task->ptrace_entry));
240 }
241 
242 #ifndef force_successful_syscall_return
243 /*
244  * System call handlers that, upon successful completion, need to return a
245  * negative value should call force_successful_syscall_return() right before
246  * returning.  On architectures where the syscall convention provides for a
247  * separate error flag (e.g., alpha, ia64, ppc{,64}, sparc{,64}, possibly
248  * others), this macro can be used to ensure that the error flag will not get
249  * set.  On architectures which do not support a separate error flag, the macro
250  * is a no-op and the spurious error condition needs to be filtered out by some
251  * other means (e.g., in user-level, by passing an extra argument to the
252  * syscall handler, or something along those lines).
253  */
254 #define force_successful_syscall_return() do { } while (0)
255 #endif
256 
257 #ifndef is_syscall_success
258 /*
259  * On most systems we can tell if a syscall is a success based on if the retval
260  * is an error value.  On some systems like ia64 and powerpc they have different
261  * indicators of success/failure and must define their own.
262  */
263 #define is_syscall_success(regs) (!IS_ERR_VALUE((unsigned long)(regs_return_value(regs))))
264 #endif
265 
266 /*
267  * <asm/ptrace.h> should define the following things inside #ifdef __KERNEL__.
268  *
269  * These do-nothing inlines are used when the arch does not
270  * implement single-step.  The kerneldoc comments are here
271  * to document the interface for all arch definitions.
272  */
273 
274 #ifndef arch_has_single_step
275 /**
276  * arch_has_single_step - does this CPU support user-mode single-step?
277  *
278  * If this is defined, then there must be function declarations or
279  * inlines for user_enable_single_step() and user_disable_single_step().
280  * arch_has_single_step() should evaluate to nonzero iff the machine
281  * supports instruction single-step for user mode.
282  * It can be a constant or it can test a CPU feature bit.
283  */
284 #define arch_has_single_step()          (0)
285 
286 /**
287  * user_enable_single_step - single-step in user-mode task
288  * @task: either current or a task stopped in %TASK_TRACED
289  *
290  * This can only be called when arch_has_single_step() has returned nonzero.
291  * Set @task so that when it returns to user mode, it will trap after the
292  * next single instruction executes.  If arch_has_block_step() is defined,
293  * this must clear the effects of user_enable_block_step() too.
294  */
295 static inline void user_enable_single_step(struct task_struct *task)
296 {
297         BUG();                  /* This can never be called.  */
298 }
299 
300 /**
301  * user_disable_single_step - cancel user-mode single-step
302  * @task: either current or a task stopped in %TASK_TRACED
303  *
304  * Clear @task of the effects of user_enable_single_step() and
305  * user_enable_block_step().  This can be called whether or not either
306  * of those was ever called on @task, and even if arch_has_single_step()
307  * returned zero.
308  */
309 static inline void user_disable_single_step(struct task_struct *task)
310 {
311 }
312 #else
313 extern void user_enable_single_step(struct task_struct *);
314 extern void user_disable_single_step(struct task_struct *);
315 #endif  /* arch_has_single_step */
316 
317 #ifndef arch_has_block_step
318 /**
319  * arch_has_block_step - does this CPU support user-mode block-step?
320  *
321  * If this is defined, then there must be a function declaration or inline
322  * for user_enable_block_step(), and arch_has_single_step() must be defined
323  * too.  arch_has_block_step() should evaluate to nonzero iff the machine
324  * supports step-until-branch for user mode.  It can be a constant or it
325  * can test a CPU feature bit.
326  */
327 #define arch_has_block_step()           (0)
328 
329 /**
330  * user_enable_block_step - step until branch in user-mode task
331  * @task: either current or a task stopped in %TASK_TRACED
332  *
333  * This can only be called when arch_has_block_step() has returned nonzero,
334  * and will never be called when single-instruction stepping is being used.
335  * Set @task so that when it returns to user mode, it will trap after the
336  * next branch or trap taken.
337  */
338 static inline void user_enable_block_step(struct task_struct *task)
339 {
340         BUG();                  /* This can never be called.  */
341 }
342 #else
343 extern void user_enable_block_step(struct task_struct *);
344 #endif  /* arch_has_block_step */
345 
346 #ifdef ARCH_HAS_USER_SINGLE_STEP_REPORT
347 extern void user_single_step_report(struct pt_regs *regs);
348 #else
349 static inline void user_single_step_report(struct pt_regs *regs)
350 {
351         kernel_siginfo_t info;
352         clear_siginfo(&info);
353         info.si_signo = SIGTRAP;
354         info.si_errno = 0;
355         info.si_code = SI_USER;
356         info.si_pid = 0;
357         info.si_uid = 0;
358         force_sig_info(&info);
359 }
360 #endif
361 
362 #ifndef arch_ptrace_stop_needed
363 /**
364  * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
365  * @code:       current->exit_code value ptrace will stop with
366  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
367  *
368  * This is called with the siglock held, to decide whether or not it's
369  * necessary to release the siglock and call arch_ptrace_stop() with the
370  * same @code and @info arguments.  It can be defined to a constant if
371  * arch_ptrace_stop() is never required, or always is.  On machines where
372  * this makes sense, it should be defined to a quick test to optimize out
373  * calling arch_ptrace_stop() when it would be superfluous.  For example,
374  * if the thread has not been back to user mode since the last stop, the
375  * thread state might indicate that nothing needs to be done.
376  *
377  * This is guaranteed to be invoked once before a task stops for ptrace and
378  * may include arch-specific operations necessary prior to a ptrace stop.
379  */
380 #define arch_ptrace_stop_needed(code, info)     (0)
381 #endif
382 
383 #ifndef arch_ptrace_stop
384 /**
385  * arch_ptrace_stop - Do machine-specific work before stopping for ptrace
386  * @code:       current->exit_code value ptrace will stop with
387  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
388  *
389  * This is called with no locks held when arch_ptrace_stop_needed() has
390  * just returned nonzero.  It is allowed to block, e.g. for user memory
391  * access.  The arch can have machine-specific work to be done before
392  * ptrace stops.  On ia64, register backing store gets written back to user
393  * memory here.  Since this can be costly (requires dropping the siglock),
394  * we only do it when the arch requires it for this particular stop, as
395  * indicated by arch_ptrace_stop_needed().
396  */
397 #define arch_ptrace_stop(code, info)            do { } while (0)
398 #endif
399 
400 #ifndef current_pt_regs
401 #define current_pt_regs() task_pt_regs(current)
402 #endif
403 
404 /*
405  * unlike current_pt_regs(), this one is equal to task_pt_regs(current)
406  * on *all* architectures; the only reason to have a per-arch definition
407  * is optimisation.
408  */
409 #ifndef signal_pt_regs
410 #define signal_pt_regs() task_pt_regs(current)
411 #endif
412 
413 #ifndef current_user_stack_pointer
414 #define current_user_stack_pointer() user_stack_pointer(current_pt_regs())
415 #endif
416 
417 extern int task_current_syscall(struct task_struct *target, struct syscall_info *info);
418 
419 extern void sigaction_compat_abi(struct k_sigaction *act, struct k_sigaction *oact);
420 #endif
421 

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