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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 
 23 #define PT_OPT_FLAG_SHIFT       3
 24 /* PT_TRACE_* event enable flags */
 25 #define PT_EVENT_FLAG(event)    (1 << (PT_OPT_FLAG_SHIFT + (event)))
 26 #define PT_TRACESYSGOOD         PT_EVENT_FLAG(0)
 27 #define PT_TRACE_FORK           PT_EVENT_FLAG(PTRACE_EVENT_FORK)
 28 #define PT_TRACE_VFORK          PT_EVENT_FLAG(PTRACE_EVENT_VFORK)
 29 #define PT_TRACE_CLONE          PT_EVENT_FLAG(PTRACE_EVENT_CLONE)
 30 #define PT_TRACE_EXEC           PT_EVENT_FLAG(PTRACE_EVENT_EXEC)
 31 #define PT_TRACE_VFORK_DONE     PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE)
 32 #define PT_TRACE_EXIT           PT_EVENT_FLAG(PTRACE_EVENT_EXIT)
 33 #define PT_TRACE_SECCOMP        PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP)
 34 
 35 #define PT_EXITKILL             (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
 36 #define PT_SUSPEND_SECCOMP      (PTRACE_O_SUSPEND_SECCOMP << 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 #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 
 84 static inline int ptrace_reparented(struct task_struct *child)
 85 {
 86         return !same_thread_group(child->real_parent, child->parent);
 87 }
 88 
 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  */
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  */
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  */
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  */
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  */
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);
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                 set_tsk_thread_flag(child, TIF_SIGPENDING);
213         }
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  */
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  */
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  */
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  */
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
337 static inline void user_single_step_siginfo(struct task_struct *tsk,
338                                 struct pt_regs *regs, siginfo_t *info)
339 {
340         memset(info, 0, sizeof(*info));
341         info->si_signo = SIGTRAP;
342 }
343 #endif
344 
345 #ifndef arch_ptrace_stop_needed
346 /**
347  * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
348  * @code:       current->exit_code value ptrace will stop with
349  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
350  *
351  * This is called with the siglock held, to decide whether or not it's
352  * necessary to release the siglock and call arch_ptrace_stop() with the
353  * same @code and @info arguments.  It can be defined to a constant if
354  * arch_ptrace_stop() is never required, or always is.  On machines where
355  * this makes sense, it should be defined to a quick test to optimize out
356  * calling arch_ptrace_stop() when it would be superfluous.  For example,
357  * if the thread has not been back to user mode since the last stop, the
358  * thread state might indicate that nothing needs to be done.
359  *
360  * This is guaranteed to be invoked once before a task stops for ptrace and
361  * may include arch-specific operations necessary prior to a ptrace stop.
362  */
363 #define arch_ptrace_stop_needed(code, info)     (0)
364 #endif
365 
366 #ifndef arch_ptrace_stop
367 /**
368  * arch_ptrace_stop - Do machine-specific work before stopping for ptrace
369  * @code:       current->exit_code value ptrace will stop with
370  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
371  *
372  * This is called with no locks held when arch_ptrace_stop_needed() has
373  * just returned nonzero.  It is allowed to block, e.g. for user memory
374  * access.  The arch can have machine-specific work to be done before
375  * ptrace stops.  On ia64, register backing store gets written back to user
376  * memory here.  Since this can be costly (requires dropping the siglock),
377  * we only do it when the arch requires it for this particular stop, as
378  * indicated by arch_ptrace_stop_needed().
379  */
380 #define arch_ptrace_stop(code, info)            do { } while (0)
381 #endif
382 
383 #ifndef current_pt_regs
384 #define current_pt_regs() task_pt_regs(current)
385 #endif
386 
387 #ifndef ptrace_signal_deliver
388 #define ptrace_signal_deliver() ((void)0)
389 #endif
390 
391 /*
392  * unlike current_pt_regs(), this one is equal to task_pt_regs(current)
393  * on *all* architectures; the only reason to have a per-arch definition
394  * is optimisation.
395  */
396 #ifndef signal_pt_regs
397 #define signal_pt_regs() task_pt_regs(current)
398 #endif
399 
400 #ifndef current_user_stack_pointer
401 #define current_user_stack_pointer() user_stack_pointer(current_pt_regs())
402 #endif
403 
404 extern int task_current_syscall(struct task_struct *target, long *callno,
405                                 unsigned long args[6], unsigned int maxargs,
406                                 unsigned long *sp, unsigned long *pc);
407 
408 #endif
409 

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