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

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  1 #ifndef _LINUX_PTRACE_H
  2 #define _LINUX_PTRACE_H
  3 
  4 #include <linux/compiler.h>             /* For unlikely.  */
  5 #include <linux/sched.h>                /* For struct task_struct.  */
  6 #include <linux/err.h>                  /* for IS_ERR_VALUE */
  7 #include <linux/bug.h>                  /* For BUG_ON.  */
  8 #include <linux/pid_namespace.h>        /* For task_active_pid_ns.  */
  9 #include <uapi/linux/ptrace.h>
 10 
 11 extern int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,
 12                             void *buf, int len, int write);
 13 
 14 /*
 15  * Ptrace flags
 16  *
 17  * The owner ship rules for task->ptrace which holds the ptrace
 18  * flags is simple.  When a task is running it owns it's task->ptrace
 19  * flags.  When the a task is stopped the ptracer owns task->ptrace.
 20  */
 21 
 22 #define PT_SEIZED       0x00010000      /* SEIZE used, enable new behavior */
 23 #define PT_PTRACED      0x00000001
 24 #define PT_DTRACE       0x00000002      /* delayed trace (used on m68k, i386) */
 25 
 26 #define PT_OPT_FLAG_SHIFT       3
 27 /* PT_TRACE_* event enable flags */
 28 #define PT_EVENT_FLAG(event)    (1 << (PT_OPT_FLAG_SHIFT + (event)))
 29 #define PT_TRACESYSGOOD         PT_EVENT_FLAG(0)
 30 #define PT_TRACE_FORK           PT_EVENT_FLAG(PTRACE_EVENT_FORK)
 31 #define PT_TRACE_VFORK          PT_EVENT_FLAG(PTRACE_EVENT_VFORK)
 32 #define PT_TRACE_CLONE          PT_EVENT_FLAG(PTRACE_EVENT_CLONE)
 33 #define PT_TRACE_EXEC           PT_EVENT_FLAG(PTRACE_EVENT_EXEC)
 34 #define PT_TRACE_VFORK_DONE     PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE)
 35 #define PT_TRACE_EXIT           PT_EVENT_FLAG(PTRACE_EVENT_EXIT)
 36 #define PT_TRACE_SECCOMP        PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP)
 37 
 38 #define PT_EXITKILL             (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
 39 
 40 /* single stepping state bits (used on ARM and PA-RISC) */
 41 #define PT_SINGLESTEP_BIT       31
 42 #define PT_SINGLESTEP           (1<<PT_SINGLESTEP_BIT)
 43 #define PT_BLOCKSTEP_BIT        30
 44 #define PT_BLOCKSTEP            (1<<PT_BLOCKSTEP_BIT)
 45 
 46 extern long arch_ptrace(struct task_struct *child, long request,
 47                         unsigned long addr, unsigned long data);
 48 extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);
 49 extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len);
 50 extern void ptrace_disable(struct task_struct *);
 51 extern int ptrace_request(struct task_struct *child, long request,
 52                           unsigned long addr, unsigned long data);
 53 extern void ptrace_notify(int exit_code);
 54 extern void __ptrace_link(struct task_struct *child,
 55                           struct task_struct *new_parent,
 56                           const struct cred *ptracer_cred);
 57 extern void __ptrace_unlink(struct task_struct *child);
 58 extern void exit_ptrace(struct task_struct *tracer);
 59 #define PTRACE_MODE_READ        0x01
 60 #define PTRACE_MODE_ATTACH      0x02
 61 #define PTRACE_MODE_NOAUDIT     0x04
 62 #define PTRACE_MODE_FSCREDS     0x08
 63 #define PTRACE_MODE_REALCREDS   0x10
 64 #define PTRACE_MODE_SCHED       0x20
 65 #define PTRACE_MODE_IBPB        0x40
 66 
 67 /* shorthands for READ/ATTACH and FSCREDS/REALCREDS combinations */
 68 #define PTRACE_MODE_READ_FSCREDS (PTRACE_MODE_READ | PTRACE_MODE_FSCREDS)
 69 #define PTRACE_MODE_READ_REALCREDS (PTRACE_MODE_READ | PTRACE_MODE_REALCREDS)
 70 #define PTRACE_MODE_ATTACH_FSCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_FSCREDS)
 71 #define PTRACE_MODE_ATTACH_REALCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_REALCREDS)
 72 #define PTRACE_MODE_SPEC_IBPB (PTRACE_MODE_ATTACH_REALCREDS | PTRACE_MODE_IBPB)
 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 /**
 91  * ptrace_may_access - check whether the caller is permitted to access
 92  * a target task.
 93  * @task: target task
 94  * @mode: selects type of access and caller credentials
 95  *
 96  * Returns true on success, false on denial.
 97  *
 98  * Similar to ptrace_may_access(). Only to be called from context switch
 99  * code. Does not call into audit and the regular LSM hooks due to locking
100  * constraints.
101  */
102 extern bool ptrace_may_access_sched(struct task_struct *task, unsigned int mode);
103 
104 static inline int ptrace_reparented(struct task_struct *child)
105 {
106         return !same_thread_group(child->real_parent, child->parent);
107 }
108 
109 static inline void ptrace_unlink(struct task_struct *child)
110 {
111         if (unlikely(child->ptrace))
112                 __ptrace_unlink(child);
113 }
114 
115 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
116                             unsigned long data);
117 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
118                             unsigned long data);
119 
120 /**
121  * ptrace_parent - return the task that is tracing the given task
122  * @task: task to consider
123  *
124  * Returns %NULL if no one is tracing @task, or the &struct task_struct
125  * pointer to its tracer.
126  *
127  * Must called under rcu_read_lock().  The pointer returned might be kept
128  * live only by RCU.  During exec, this may be called with task_lock() held
129  * on @task, still held from when check_unsafe_exec() was called.
130  */
131 static inline struct task_struct *ptrace_parent(struct task_struct *task)
132 {
133         if (unlikely(task->ptrace))
134                 return rcu_dereference(task->parent);
135         return NULL;
136 }
137 
138 /**
139  * ptrace_event_enabled - test whether a ptrace event is enabled
140  * @task: ptracee of interest
141  * @event: %PTRACE_EVENT_* to test
142  *
143  * Test whether @event is enabled for ptracee @task.
144  *
145  * Returns %true if @event is enabled, %false otherwise.
146  */
147 static inline bool ptrace_event_enabled(struct task_struct *task, int event)
148 {
149         return task->ptrace & PT_EVENT_FLAG(event);
150 }
151 
152 /**
153  * ptrace_event - possibly stop for a ptrace event notification
154  * @event:      %PTRACE_EVENT_* value to report
155  * @message:    value for %PTRACE_GETEVENTMSG to return
156  *
157  * Check whether @event is enabled and, if so, report @event and @message
158  * to the ptrace parent.
159  *
160  * Called without locks.
161  */
162 static inline void ptrace_event(int event, unsigned long message)
163 {
164         if (unlikely(ptrace_event_enabled(current, event))) {
165                 current->ptrace_message = message;
166                 ptrace_notify((event << 8) | SIGTRAP);
167         } else if (event == PTRACE_EVENT_EXEC) {
168                 /* legacy EXEC report via SIGTRAP */
169                 if ((current->ptrace & (PT_PTRACED|PT_SEIZED)) == PT_PTRACED)
170                         send_sig(SIGTRAP, current, 0);
171         }
172 }
173 
174 /**
175  * ptrace_event_pid - possibly stop for a ptrace event notification
176  * @event:      %PTRACE_EVENT_* value to report
177  * @pid:        process identifier for %PTRACE_GETEVENTMSG to return
178  *
179  * Check whether @event is enabled and, if so, report @event and @pid
180  * to the ptrace parent.  @pid is reported as the pid_t seen from the
181  * the ptrace parent's pid namespace.
182  *
183  * Called without locks.
184  */
185 static inline void ptrace_event_pid(int event, struct pid *pid)
186 {
187         /*
188          * FIXME: There's a potential race if a ptracer in a different pid
189          * namespace than parent attaches between computing message below and
190          * when we acquire tasklist_lock in ptrace_stop().  If this happens,
191          * the ptracer will get a bogus pid from PTRACE_GETEVENTMSG.
192          */
193         unsigned long message = 0;
194         struct pid_namespace *ns;
195 
196         rcu_read_lock();
197         ns = task_active_pid_ns(rcu_dereference(current->parent));
198         if (ns)
199                 message = pid_nr_ns(pid, ns);
200         rcu_read_unlock();
201 
202         ptrace_event(event, message);
203 }
204 
205 /**
206  * ptrace_init_task - initialize ptrace state for a new child
207  * @child:              new child task
208  * @ptrace:             true if child should be ptrace'd by parent's tracer
209  *
210  * This is called immediately after adding @child to its parent's children
211  * list.  @ptrace is false in the normal case, and true to ptrace @child.
212  *
213  * Called with current's siglock and write_lock_irq(&tasklist_lock) held.
214  */
215 static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
216 {
217         INIT_LIST_HEAD(&child->ptrace_entry);
218         INIT_LIST_HEAD(&child->ptraced);
219         child->jobctl = 0;
220         child->ptrace = 0;
221         child->parent = child->real_parent;
222 
223         if (unlikely(ptrace) && current->ptrace) {
224                 child->ptrace = current->ptrace;
225                 __ptrace_link(child, current->parent, current->ptracer_cred);
226 
227                 if (child->ptrace & PT_SEIZED)
228                         task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
229                 else
230                         sigaddset(&child->pending.signal, SIGSTOP);
231 
232                 set_tsk_thread_flag(child, TIF_SIGPENDING);
233         }
234         else
235                 child->ptracer_cred = NULL;
236 }
237 
238 /**
239  * ptrace_release_task - final ptrace-related cleanup of a zombie being reaped
240  * @task:       task in %EXIT_DEAD state
241  *
242  * Called with write_lock(&tasklist_lock) held.
243  */
244 static inline void ptrace_release_task(struct task_struct *task)
245 {
246         BUG_ON(!list_empty(&task->ptraced));
247         ptrace_unlink(task);
248         BUG_ON(!list_empty(&task->ptrace_entry));
249 }
250 
251 #ifndef force_successful_syscall_return
252 /*
253  * System call handlers that, upon successful completion, need to return a
254  * negative value should call force_successful_syscall_return() right before
255  * returning.  On architectures where the syscall convention provides for a
256  * separate error flag (e.g., alpha, ia64, ppc{,64}, sparc{,64}, possibly
257  * others), this macro can be used to ensure that the error flag will not get
258  * set.  On architectures which do not support a separate error flag, the macro
259  * is a no-op and the spurious error condition needs to be filtered out by some
260  * other means (e.g., in user-level, by passing an extra argument to the
261  * syscall handler, or something along those lines).
262  */
263 #define force_successful_syscall_return() do { } while (0)
264 #endif
265 
266 #ifndef is_syscall_success
267 /*
268  * On most systems we can tell if a syscall is a success based on if the retval
269  * is an error value.  On some systems like ia64 and powerpc they have different
270  * indicators of success/failure and must define their own.
271  */
272 #define is_syscall_success(regs) (!IS_ERR_VALUE((unsigned long)(regs_return_value(regs))))
273 #endif
274 
275 /*
276  * <asm/ptrace.h> should define the following things inside #ifdef __KERNEL__.
277  *
278  * These do-nothing inlines are used when the arch does not
279  * implement single-step.  The kerneldoc comments are here
280  * to document the interface for all arch definitions.
281  */
282 
283 #ifndef arch_has_single_step
284 /**
285  * arch_has_single_step - does this CPU support user-mode single-step?
286  *
287  * If this is defined, then there must be function declarations or
288  * inlines for user_enable_single_step() and user_disable_single_step().
289  * arch_has_single_step() should evaluate to nonzero iff the machine
290  * supports instruction single-step for user mode.
291  * It can be a constant or it can test a CPU feature bit.
292  */
293 #define arch_has_single_step()          (0)
294 
295 /**
296  * user_enable_single_step - single-step in user-mode task
297  * @task: either current or a task stopped in %TASK_TRACED
298  *
299  * This can only be called when arch_has_single_step() has returned nonzero.
300  * Set @task so that when it returns to user mode, it will trap after the
301  * next single instruction executes.  If arch_has_block_step() is defined,
302  * this must clear the effects of user_enable_block_step() too.
303  */
304 static inline void user_enable_single_step(struct task_struct *task)
305 {
306         BUG();                  /* This can never be called.  */
307 }
308 
309 /**
310  * user_disable_single_step - cancel user-mode single-step
311  * @task: either current or a task stopped in %TASK_TRACED
312  *
313  * Clear @task of the effects of user_enable_single_step() and
314  * user_enable_block_step().  This can be called whether or not either
315  * of those was ever called on @task, and even if arch_has_single_step()
316  * returned zero.
317  */
318 static inline void user_disable_single_step(struct task_struct *task)
319 {
320 }
321 #else
322 extern void user_enable_single_step(struct task_struct *);
323 extern void user_disable_single_step(struct task_struct *);
324 #endif  /* arch_has_single_step */
325 
326 #ifndef arch_has_block_step
327 /**
328  * arch_has_block_step - does this CPU support user-mode block-step?
329  *
330  * If this is defined, then there must be a function declaration or inline
331  * for user_enable_block_step(), and arch_has_single_step() must be defined
332  * too.  arch_has_block_step() should evaluate to nonzero iff the machine
333  * supports step-until-branch for user mode.  It can be a constant or it
334  * can test a CPU feature bit.
335  */
336 #define arch_has_block_step()           (0)
337 
338 /**
339  * user_enable_block_step - step until branch in user-mode task
340  * @task: either current or a task stopped in %TASK_TRACED
341  *
342  * This can only be called when arch_has_block_step() has returned nonzero,
343  * and will never be called when single-instruction stepping is being used.
344  * Set @task so that when it returns to user mode, it will trap after the
345  * next branch or trap taken.
346  */
347 static inline void user_enable_block_step(struct task_struct *task)
348 {
349         BUG();                  /* This can never be called.  */
350 }
351 #else
352 extern void user_enable_block_step(struct task_struct *);
353 #endif  /* arch_has_block_step */
354 
355 #ifdef ARCH_HAS_USER_SINGLE_STEP_INFO
356 extern void user_single_step_siginfo(struct task_struct *tsk,
357                                 struct pt_regs *regs, siginfo_t *info);
358 #else
359 static inline void user_single_step_siginfo(struct task_struct *tsk,
360                                 struct pt_regs *regs, siginfo_t *info)
361 {
362         memset(info, 0, sizeof(*info));
363         info->si_signo = SIGTRAP;
364 }
365 #endif
366 
367 #ifndef arch_ptrace_stop_needed
368 /**
369  * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
370  * @code:       current->exit_code value ptrace will stop with
371  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
372  *
373  * This is called with the siglock held, to decide whether or not it's
374  * necessary to release the siglock and call arch_ptrace_stop() with the
375  * same @code and @info arguments.  It can be defined to a constant if
376  * arch_ptrace_stop() is never required, or always is.  On machines where
377  * this makes sense, it should be defined to a quick test to optimize out
378  * calling arch_ptrace_stop() when it would be superfluous.  For example,
379  * if the thread has not been back to user mode since the last stop, the
380  * thread state might indicate that nothing needs to be done.
381  *
382  * This is guaranteed to be invoked once before a task stops for ptrace and
383  * may include arch-specific operations necessary prior to a ptrace stop.
384  */
385 #define arch_ptrace_stop_needed(code, info)     (0)
386 #endif
387 
388 #ifndef arch_ptrace_stop
389 /**
390  * arch_ptrace_stop - Do machine-specific work before stopping for ptrace
391  * @code:       current->exit_code value ptrace will stop with
392  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
393  *
394  * This is called with no locks held when arch_ptrace_stop_needed() has
395  * just returned nonzero.  It is allowed to block, e.g. for user memory
396  * access.  The arch can have machine-specific work to be done before
397  * ptrace stops.  On ia64, register backing store gets written back to user
398  * memory here.  Since this can be costly (requires dropping the siglock),
399  * we only do it when the arch requires it for this particular stop, as
400  * indicated by arch_ptrace_stop_needed().
401  */
402 #define arch_ptrace_stop(code, info)            do { } while (0)
403 #endif
404 
405 #ifndef current_pt_regs
406 #define current_pt_regs() task_pt_regs(current)
407 #endif
408 
409 #ifndef ptrace_signal_deliver
410 #define ptrace_signal_deliver() ((void)0)
411 #endif
412 
413 /*
414  * unlike current_pt_regs(), this one is equal to task_pt_regs(current)
415  * on *all* architectures; the only reason to have a per-arch definition
416  * is optimisation.
417  */
418 #ifndef signal_pt_regs
419 #define signal_pt_regs() task_pt_regs(current)
420 #endif
421 
422 #ifndef current_user_stack_pointer
423 #define current_user_stack_pointer() user_stack_pointer(current_pt_regs())
424 #endif
425 
426 extern int task_current_syscall(struct task_struct *target, long *callno,
427                                 unsigned long args[6], unsigned int maxargs,
428                                 unsigned long *sp, unsigned long *pc);
429 
430 #endif
431 

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