include/linux/ptrace.h

   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