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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 /*
 12  * Ptrace flags
 13  *
 14  * The owner ship rules for task->ptrace which holds the ptrace
 15  * flags is simple.  When a task is running it owns it's task->ptrace
 16  * flags.  When the a task is stopped the ptracer owns task->ptrace.
 17  */
 18 
 19 #define PT_SEIZED       0x00010000      /* SEIZE used, enable new behavior */
 20 #define PT_PTRACED      0x00000001
 21 #define PT_DTRACE       0x00000002      /* delayed trace (used on m68k, i386) */
 22 #define PT_PTRACE_CAP   0x00000004      /* ptracer can follow suid-exec */
 23 
 24 #define PT_OPT_FLAG_SHIFT       3
 25 /* PT_TRACE_* event enable flags */
 26 #define PT_EVENT_FLAG(event)    (1 << (PT_OPT_FLAG_SHIFT + (event)))
 27 #define PT_TRACESYSGOOD         PT_EVENT_FLAG(0)
 28 #define PT_TRACE_FORK           PT_EVENT_FLAG(PTRACE_EVENT_FORK)
 29 #define PT_TRACE_VFORK          PT_EVENT_FLAG(PTRACE_EVENT_VFORK)
 30 #define PT_TRACE_CLONE          PT_EVENT_FLAG(PTRACE_EVENT_CLONE)
 31 #define PT_TRACE_EXEC           PT_EVENT_FLAG(PTRACE_EVENT_EXEC)
 32 #define PT_TRACE_VFORK_DONE     PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE)
 33 #define PT_TRACE_EXIT           PT_EVENT_FLAG(PTRACE_EVENT_EXIT)
 34 #define PT_TRACE_SECCOMP        PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP)
 35 
 36 #define PT_EXITKILL             (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
 37 
 38 /* single stepping state bits (used on ARM and PA-RISC) */
 39 #define PT_SINGLESTEP_BIT       31
 40 #define PT_SINGLESTEP           (1<<PT_SINGLESTEP_BIT)
 41 #define PT_BLOCKSTEP_BIT        30
 42 #define PT_BLOCKSTEP            (1<<PT_BLOCKSTEP_BIT)
 43 
 44 extern long arch_ptrace(struct task_struct *child, long request,
 45                         unsigned long addr, unsigned long data);
 46 extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);
 47 extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len);
 48 extern void ptrace_disable(struct task_struct *);
 49 extern int ptrace_request(struct task_struct *child, long request,
 50                           unsigned long addr, unsigned long data);
 51 extern void ptrace_notify(int exit_code);
 52 extern void __ptrace_link(struct task_struct *child,
 53                           struct task_struct *new_parent);
 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 /* Returns true on success, false on denial. */
 60 extern bool ptrace_may_access(struct task_struct *task, unsigned int mode);
 61 
 62 static inline int ptrace_reparented(struct task_struct *child)
 63 {
 64         return !same_thread_group(child->real_parent, child->parent);
 65 }
 66 
 67 static inline void ptrace_unlink(struct task_struct *child)
 68 {
 69         if (unlikely(child->ptrace))
 70                 __ptrace_unlink(child);
 71 }
 72 
 73 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
 74                             unsigned long data);
 75 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
 76                             unsigned long data);
 77 
 78 /**
 79  * ptrace_parent - return the task that is tracing the given task
 80  * @task: task to consider
 81  *
 82  * Returns %NULL if no one is tracing @task, or the &struct task_struct
 83  * pointer to its tracer.
 84  *
 85  * Must called under rcu_read_lock().  The pointer returned might be kept
 86  * live only by RCU.  During exec, this may be called with task_lock() held
 87  * on @task, still held from when check_unsafe_exec() was called.
 88  */
 89 static inline struct task_struct *ptrace_parent(struct task_struct *task)
 90 {
 91         if (unlikely(task->ptrace))
 92                 return rcu_dereference(task->parent);
 93         return NULL;
 94 }
 95 
 96 /**
 97  * ptrace_event_enabled - test whether a ptrace event is enabled
 98  * @task: ptracee of interest
 99  * @event: %PTRACE_EVENT_* to test
100  *
101  * Test whether @event is enabled for ptracee @task.
102  *
103  * Returns %true if @event is enabled, %false otherwise.
104  */
105 static inline bool ptrace_event_enabled(struct task_struct *task, int event)
106 {
107         return task->ptrace & PT_EVENT_FLAG(event);
108 }
109 
110 /**
111  * ptrace_event - possibly stop for a ptrace event notification
112  * @event:      %PTRACE_EVENT_* value to report
113  * @message:    value for %PTRACE_GETEVENTMSG to return
114  *
115  * Check whether @event is enabled and, if so, report @event and @message
116  * to the ptrace parent.
117  *
118  * Called without locks.
119  */
120 static inline void ptrace_event(int event, unsigned long message)
121 {
122         if (unlikely(ptrace_event_enabled(current, event))) {
123                 current->ptrace_message = message;
124                 ptrace_notify((event << 8) | SIGTRAP);
125         } else if (event == PTRACE_EVENT_EXEC) {
126                 /* legacy EXEC report via SIGTRAP */
127                 if ((current->ptrace & (PT_PTRACED|PT_SEIZED)) == PT_PTRACED)
128                         send_sig(SIGTRAP, current, 0);
129         }
130 }
131 
132 /**
133  * ptrace_event_pid - possibly stop for a ptrace event notification
134  * @event:      %PTRACE_EVENT_* value to report
135  * @pid:        process identifier for %PTRACE_GETEVENTMSG to return
136  *
137  * Check whether @event is enabled and, if so, report @event and @pid
138  * to the ptrace parent.  @pid is reported as the pid_t seen from the
139  * the ptrace parent's pid namespace.
140  *
141  * Called without locks.
142  */
143 static inline void ptrace_event_pid(int event, struct pid *pid)
144 {
145         /*
146          * FIXME: There's a potential race if a ptracer in a different pid
147          * namespace than parent attaches between computing message below and
148          * when we acquire tasklist_lock in ptrace_stop().  If this happens,
149          * the ptracer will get a bogus pid from PTRACE_GETEVENTMSG.
150          */
151         unsigned long message = 0;
152         struct pid_namespace *ns;
153 
154         rcu_read_lock();
155         ns = task_active_pid_ns(rcu_dereference(current->parent));
156         if (ns)
157                 message = pid_nr_ns(pid, ns);
158         rcu_read_unlock();
159 
160         ptrace_event(event, message);
161 }
162 
163 /**
164  * ptrace_init_task - initialize ptrace state for a new child
165  * @child:              new child task
166  * @ptrace:             true if child should be ptrace'd by parent's tracer
167  *
168  * This is called immediately after adding @child to its parent's children
169  * list.  @ptrace is false in the normal case, and true to ptrace @child.
170  *
171  * Called with current's siglock and write_lock_irq(&tasklist_lock) held.
172  */
173 static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
174 {
175         INIT_LIST_HEAD(&child->ptrace_entry);
176         INIT_LIST_HEAD(&child->ptraced);
177         child->jobctl = 0;
178         child->ptrace = 0;
179         child->parent = child->real_parent;
180 
181         if (unlikely(ptrace) && current->ptrace) {
182                 child->ptrace = current->ptrace;
183                 __ptrace_link(child, current->parent);
184 
185                 if (child->ptrace & PT_SEIZED)
186                         task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
187                 else
188                         sigaddset(&child->pending.signal, SIGSTOP);
189 
190                 set_tsk_thread_flag(child, TIF_SIGPENDING);
191         }
192 }
193 
194 /**
195  * ptrace_release_task - final ptrace-related cleanup of a zombie being reaped
196  * @task:       task in %EXIT_DEAD state
197  *
198  * Called with write_lock(&tasklist_lock) held.
199  */
200 static inline void ptrace_release_task(struct task_struct *task)
201 {
202         BUG_ON(!list_empty(&task->ptraced));
203         ptrace_unlink(task);
204         BUG_ON(!list_empty(&task->ptrace_entry));
205 }
206 
207 #ifndef force_successful_syscall_return
208 /*
209  * System call handlers that, upon successful completion, need to return a
210  * negative value should call force_successful_syscall_return() right before
211  * returning.  On architectures where the syscall convention provides for a
212  * separate error flag (e.g., alpha, ia64, ppc{,64}, sparc{,64}, possibly
213  * others), this macro can be used to ensure that the error flag will not get
214  * set.  On architectures which do not support a separate error flag, the macro
215  * is a no-op and the spurious error condition needs to be filtered out by some
216  * other means (e.g., in user-level, by passing an extra argument to the
217  * syscall handler, or something along those lines).
218  */
219 #define force_successful_syscall_return() do { } while (0)
220 #endif
221 
222 #ifndef is_syscall_success
223 /*
224  * On most systems we can tell if a syscall is a success based on if the retval
225  * is an error value.  On some systems like ia64 and powerpc they have different
226  * indicators of success/failure and must define their own.
227  */
228 #define is_syscall_success(regs) (!IS_ERR_VALUE((unsigned long)(regs_return_value(regs))))
229 #endif
230 
231 /*
232  * <asm/ptrace.h> should define the following things inside #ifdef __KERNEL__.
233  *
234  * These do-nothing inlines are used when the arch does not
235  * implement single-step.  The kerneldoc comments are here
236  * to document the interface for all arch definitions.
237  */
238 
239 #ifndef arch_has_single_step
240 /**
241  * arch_has_single_step - does this CPU support user-mode single-step?
242  *
243  * If this is defined, then there must be function declarations or
244  * inlines for user_enable_single_step() and user_disable_single_step().
245  * arch_has_single_step() should evaluate to nonzero iff the machine
246  * supports instruction single-step for user mode.
247  * It can be a constant or it can test a CPU feature bit.
248  */
249 #define arch_has_single_step()          (0)
250 
251 /**
252  * user_enable_single_step - single-step in user-mode task
253  * @task: either current or a task stopped in %TASK_TRACED
254  *
255  * This can only be called when arch_has_single_step() has returned nonzero.
256  * Set @task so that when it returns to user mode, it will trap after the
257  * next single instruction executes.  If arch_has_block_step() is defined,
258  * this must clear the effects of user_enable_block_step() too.
259  */
260 static inline void user_enable_single_step(struct task_struct *task)
261 {
262         BUG();                  /* This can never be called.  */
263 }
264 
265 /**
266  * user_disable_single_step - cancel user-mode single-step
267  * @task: either current or a task stopped in %TASK_TRACED
268  *
269  * Clear @task of the effects of user_enable_single_step() and
270  * user_enable_block_step().  This can be called whether or not either
271  * of those was ever called on @task, and even if arch_has_single_step()
272  * returned zero.
273  */
274 static inline void user_disable_single_step(struct task_struct *task)
275 {
276 }
277 #else
278 extern void user_enable_single_step(struct task_struct *);
279 extern void user_disable_single_step(struct task_struct *);
280 #endif  /* arch_has_single_step */
281 
282 #ifndef arch_has_block_step
283 /**
284  * arch_has_block_step - does this CPU support user-mode block-step?
285  *
286  * If this is defined, then there must be a function declaration or inline
287  * for user_enable_block_step(), and arch_has_single_step() must be defined
288  * too.  arch_has_block_step() should evaluate to nonzero iff the machine
289  * supports step-until-branch for user mode.  It can be a constant or it
290  * can test a CPU feature bit.
291  */
292 #define arch_has_block_step()           (0)
293 
294 /**
295  * user_enable_block_step - step until branch in user-mode task
296  * @task: either current or a task stopped in %TASK_TRACED
297  *
298  * This can only be called when arch_has_block_step() has returned nonzero,
299  * and will never be called when single-instruction stepping is being used.
300  * Set @task so that when it returns to user mode, it will trap after the
301  * next branch or trap taken.
302  */
303 static inline void user_enable_block_step(struct task_struct *task)
304 {
305         BUG();                  /* This can never be called.  */
306 }
307 #else
308 extern void user_enable_block_step(struct task_struct *);
309 #endif  /* arch_has_block_step */
310 
311 #ifdef ARCH_HAS_USER_SINGLE_STEP_INFO
312 extern void user_single_step_siginfo(struct task_struct *tsk,
313                                 struct pt_regs *regs, siginfo_t *info);
314 #else
315 static inline void user_single_step_siginfo(struct task_struct *tsk,
316                                 struct pt_regs *regs, siginfo_t *info)
317 {
318         memset(info, 0, sizeof(*info));
319         info->si_signo = SIGTRAP;
320 }
321 #endif
322 
323 #ifndef arch_ptrace_stop_needed
324 /**
325  * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
326  * @code:       current->exit_code value ptrace will stop with
327  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
328  *
329  * This is called with the siglock held, to decide whether or not it's
330  * necessary to release the siglock and call arch_ptrace_stop() with the
331  * same @code and @info arguments.  It can be defined to a constant if
332  * arch_ptrace_stop() is never required, or always is.  On machines where
333  * this makes sense, it should be defined to a quick test to optimize out
334  * calling arch_ptrace_stop() when it would be superfluous.  For example,
335  * if the thread has not been back to user mode since the last stop, the
336  * thread state might indicate that nothing needs to be done.
337  *
338  * This is guaranteed to be invoked once before a task stops for ptrace and
339  * may include arch-specific operations necessary prior to a ptrace stop.
340  */
341 #define arch_ptrace_stop_needed(code, info)     (0)
342 #endif
343 
344 #ifndef arch_ptrace_stop
345 /**
346  * arch_ptrace_stop - Do machine-specific work before stopping for ptrace
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 no locks held when arch_ptrace_stop_needed() has
351  * just returned nonzero.  It is allowed to block, e.g. for user memory
352  * access.  The arch can have machine-specific work to be done before
353  * ptrace stops.  On ia64, register backing store gets written back to user
354  * memory here.  Since this can be costly (requires dropping the siglock),
355  * we only do it when the arch requires it for this particular stop, as
356  * indicated by arch_ptrace_stop_needed().
357  */
358 #define arch_ptrace_stop(code, info)            do { } while (0)
359 #endif
360 
361 #ifndef current_pt_regs
362 #define current_pt_regs() task_pt_regs(current)
363 #endif
364 
365 #ifndef ptrace_signal_deliver
366 #define ptrace_signal_deliver() ((void)0)
367 #endif
368 
369 /*
370  * unlike current_pt_regs(), this one is equal to task_pt_regs(current)
371  * on *all* architectures; the only reason to have a per-arch definition
372  * is optimisation.
373  */
374 #ifndef signal_pt_regs
375 #define signal_pt_regs() task_pt_regs(current)
376 #endif
377 
378 #ifndef current_user_stack_pointer
379 #define current_user_stack_pointer() user_stack_pointer(current_pt_regs())
380 #endif
381 
382 extern int task_current_syscall(struct task_struct *target, long *callno,
383                                 unsigned long args[6], unsigned int maxargs,
384                                 unsigned long *sp, unsigned long *pc);
385 
386 #endif
387 

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