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 #define PT_SUSPEND_SECCOMP      (PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT)
  38
  39 /* single stepping state bits (used on ARM and PA-RISC) */
  40 #define PT_SINGLESTEP_BIT       31
  41 #define PT_SINGLESTEP           (1<<PT_SINGLESTEP_BIT)
  42 #define PT_BLOCKSTEP_BIT        30
  43 #define PT_BLOCKSTEP            (1<<PT_BLOCKSTEP_BIT)
  44
  45 extern long arch_ptrace(struct task_struct *child, long request,
  46                         unsigned long addr, unsigned long data);
  47 extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);
  48 extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len);
  49 extern void ptrace_disable(struct task_struct *);
  50 extern int ptrace_request(struct task_struct *child, long request,
  51                           unsigned long addr, unsigned long data);
  52 extern void ptrace_notify(int exit_code);
  53 extern void __ptrace_link(struct task_struct *child,
  54                           struct task_struct *new_parent);
  55 extern void __ptrace_unlink(struct task_struct *child);
  56 extern void exit_ptrace(struct task_struct *tracer, struct list_head *dead);
  57 #define PTRACE_MODE_READ        0x01
  58 #define PTRACE_MODE_ATTACH      0x02
  59 #define PTRACE_MODE_NOAUDIT     0x04
  60 /* Returns true on success, false on denial. */
  61 extern bool ptrace_may_access(struct task_struct *task, unsigned int mode);
  62
  63 static inline int ptrace_reparented(struct task_struct *child)
  64 {
  65         return !same_thread_group(child->real_parent, child->parent);
  66 }
  67
  68 static inline void ptrace_unlink(struct task_struct *child)
  69 {
  70         if (unlikely(child->ptrace))
  71                 __ptrace_unlink(child);
  72 }
  73
  74 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
  75                             unsigned long data);
  76 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
  77                             unsigned long data);
  78
  79 /**
  80  * ptrace_parent - return the task that is tracing the given task
  81  * @task: task to consider
  82  *
  83  * Returns %NULL if no one is tracing @task, or the &struct task_struct
  84  * pointer to its tracer.
  85  *
  86  * Must called under rcu_read_lock().  The pointer returned might be kept
  87  * live only by RCU.  During exec, this may be called with task_lock() held
  88  * on @task, still held from when check_unsafe_exec() was called.
  89  */
  90 static inline struct task_struct *ptrace_parent(struct task_struct *task)
  91 {
  92         if (unlikely(task->ptrace))
  93                 return rcu_dereference(task->parent);
  94         return NULL;
  95 }
  96
  97 /**
  98  * ptrace_event_enabled - test whether a ptrace event is enabled
  99  * @task: ptracee of interest
 100  * @event: %PTRACE_EVENT_* to test
 101  *
 102  * Test whether @event is enabled for ptracee @task.
 103  *
 104  * Returns %true if @event is enabled, %false otherwise.
 105  */
 106 static inline bool ptrace_event_enabled(struct task_struct *task, int event)
 107 {
 108         return task->ptrace & PT_EVENT_FLAG(event);
 109 }
 110
 111 /**
 112  * ptrace_event - possibly stop for a ptrace event notification
 113  * @event:      %PTRACE_EVENT_* value to report
 114  * @message:    value for %PTRACE_GETEVENTMSG to return
 115  *
 116  * Check whether @event is enabled and, if so, report @event and @message
 117  * to the ptrace parent.
 118  *
 119  * Called without locks.
 120  */
 121 static inline void ptrace_event(int event, unsigned long message)
 122 {
 123         if (unlikely(ptrace_event_enabled(current, event))) {
 124                 current->ptrace_message = message;
 125                 ptrace_notify((event << 8) | SIGTRAP);
 126         } else if (event == PTRACE_EVENT_EXEC) {
 127                 /* legacy EXEC report via SIGTRAP */
 128                 if ((current->ptrace & (PT_PTRACED|PT_SEIZED)) == PT_PTRACED)
 129                         send_sig(SIGTRAP, current, 0);
 130         }
 131 }
 132
 133 /**
 134  * ptrace_event_pid - possibly stop for a ptrace event notification
 135  * @event:      %PTRACE_EVENT_* value to report
 136  * @pid:        process identifier for %PTRACE_GETEVENTMSG to return
 137  *
 138  * Check whether @event is enabled and, if so, report @event and @pid
 139  * to the ptrace parent.  @pid is reported as the pid_t seen from the
 140  * the ptrace parent's pid namespace.
 141  *
 142  * Called without locks.
 143  */
 144 static inline void ptrace_event_pid(int event, struct pid *pid)
 145 {
 146         /*
 147          * FIXME: There's a potential race if a ptracer in a different pid
 148          * namespace than parent attaches between computing message below and
 149          * when we acquire tasklist_lock in ptrace_stop().  If this happens,
 150          * the ptracer will get a bogus pid from PTRACE_GETEVENTMSG.
 151          */
 152         unsigned long message = 0;
 153         struct pid_namespace *ns;
 154
 155         rcu_read_lock();
 156         ns = task_active_pid_ns(rcu_dereference(current->parent));
 157         if (ns)
 158                 message = pid_nr_ns(pid, ns);
 159         rcu_read_unlock();
 160
 161         ptrace_event(event, message);
 162 }
 163
 164 /**
 165  * ptrace_init_task - initialize ptrace state for a new child
 166  * @child:              new child task
 167  * @ptrace:             true if child should be ptrace'd by parent's tracer
 168  *
 169  * This is called immediately after adding @child to its parent's children
 170  * list.  @ptrace is false in the normal case, and true to ptrace @child.
 171  *
 172  * Called with current's siglock and write_lock_irq(&tasklist_lock) held.
 173  */
 174 static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
 175 {
 176         INIT_LIST_HEAD(&child->ptrace_entry);
 177         INIT_LIST_HEAD(&child->ptraced);
 178         child->jobctl = 0;
 179         child->ptrace = 0;
 180         child->parent = child->real_parent;
 181
 182         if (unlikely(ptrace) && current->ptrace) {
 183                 child->ptrace = current->ptrace;
 184                 __ptrace_link(child, current->parent);
 185
 186                 if (child->ptrace & PT_SEIZED)
 187                         task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
 188                 else
 189                         sigaddset(&child->pending.signal, SIGSTOP);
 190
 191                 set_tsk_thread_flag(child, TIF_SIGPENDING);
 192         }
 193 }
 194
 195 /**
 196  * ptrace_release_task - final ptrace-related cleanup of a zombie being reaped
 197  * @task:       task in %EXIT_DEAD state
 198  *
 199  * Called with write_lock(&tasklist_lock) held.
 200  */
 201 static inline void ptrace_release_task(struct task_struct *task)
 202 {
 203         BUG_ON(!list_empty(&task->ptraced));
 204         ptrace_unlink(task);
 205         BUG_ON(!list_empty(&task->ptrace_entry));
 206 }
 207
 208 #ifndef force_successful_syscall_return
 209 /*
 210  * System call handlers that, upon successful completion, need to return a
 211  * negative value should call force_successful_syscall_return() right before
 212  * returning.  On architectures where the syscall convention provides for a
 213  * separate error flag (e.g., alpha, ia64, ppc{,64}, sparc{,64}, possibly
 214  * others), this macro can be used to ensure that the error flag will not get
 215  * set.  On architectures which do not support a separate error flag, the macro
 216  * is a no-op and the spurious error condition needs to be filtered out by some
 217  * other means (e.g., in user-level, by passing an extra argument to the
 218  * syscall handler, or something along those lines).
 219  */
 220 #define force_successful_syscall_return() do { } while (0)
 221 #endif
 222
 223 #ifndef is_syscall_success
 224 /*
 225  * On most systems we can tell if a syscall is a success based on if the retval
 226  * is an error value.  On some systems like ia64 and powerpc they have different
 227  * indicators of success/failure and must define their own.
 228  */
 229 #define is_syscall_success(regs) (!IS_ERR_VALUE((unsigned long)(regs_return_value(regs))))
 230 #endif
 231
 232 /*
 233  * <asm/ptrace.h> should define the following things inside #ifdef __KERNEL__.
 234  *
 235  * These do-nothing inlines are used when the arch does not
 236  * implement single-step.  The kerneldoc comments are here
 237  * to document the interface for all arch definitions.
 238  */
 239
 240 #ifndef arch_has_single_step
 241 /**
 242  * arch_has_single_step - does this CPU support user-mode single-step?
 243  *
 244  * If this is defined, then there must be function declarations or
 245  * inlines for user_enable_single_step() and user_disable_single_step().
 246  * arch_has_single_step() should evaluate to nonzero iff the machine
 247  * supports instruction single-step for user mode.
 248  * It can be a constant or it can test a CPU feature bit.
 249  */
 250 #define arch_has_single_step()          (0)
 251
 252 /**
 253  * user_enable_single_step - single-step in user-mode task
 254  * @task: either current or a task stopped in %TASK_TRACED
 255  *
 256  * This can only be called when arch_has_single_step() has returned nonzero.
 257  * Set @task so that when it returns to user mode, it will trap after the
 258  * next single instruction executes.  If arch_has_block_step() is defined,
 259  * this must clear the effects of user_enable_block_step() too.
 260  */
 261 static inline void user_enable_single_step(struct task_struct *task)
 262 {
 263         BUG();                  /* This can never be called.  */
 264 }
 265
 266 /**
 267  * user_disable_single_step - cancel user-mode single-step
 268  * @task: either current or a task stopped in %TASK_TRACED
 269  *
 270  * Clear @task of the effects of user_enable_single_step() and
 271  * user_enable_block_step().  This can be called whether or not either
 272  * of those was ever called on @task, and even if arch_has_single_step()
 273  * returned zero.
 274  */
 275 static inline void user_disable_single_step(struct task_struct *task)
 276 {
 277 }
 278 #else
 279 extern void user_enable_single_step(struct task_struct *);
 280 extern void user_disable_single_step(struct task_struct *);
 281 #endif  /* arch_has_single_step */
 282
 283 #ifndef arch_has_block_step
 284 /**
 285  * arch_has_block_step - does this CPU support user-mode block-step?
 286  *
 287  * If this is defined, then there must be a function declaration or inline
 288  * for user_enable_block_step(), and arch_has_single_step() must be defined
 289  * too.  arch_has_block_step() should evaluate to nonzero iff the machine
 290  * supports step-until-branch for user mode.  It can be a constant or it
 291  * can test a CPU feature bit.
 292  */
 293 #define arch_has_block_step()           (0)
 294
 295 /**
 296  * user_enable_block_step - step until branch 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_block_step() has returned nonzero,
 300  * and will never be called when single-instruction stepping is being used.
 301  * Set @task so that when it returns to user mode, it will trap after the
 302  * next branch or trap taken.
 303  */
 304 static inline void user_enable_block_step(struct task_struct *task)
 305 {
 306         BUG();                  /* This can never be called.  */
 307 }
 308 #else
 309 extern void user_enable_block_step(struct task_struct *);
 310 #endif  /* arch_has_block_step */
 311
 312 #ifdef ARCH_HAS_USER_SINGLE_STEP_INFO
 313 extern void user_single_step_siginfo(struct task_struct *tsk,
 314                                 struct pt_regs *regs, siginfo_t *info);
 315 #else
 316 static inline void user_single_step_siginfo(struct task_struct *tsk,
 317                                 struct pt_regs *regs, siginfo_t *info)
 318 {
 319         memset(info, 0, sizeof(*info));
 320         info->si_signo = SIGTRAP;
 321 }
 322 #endif
 323
 324 #ifndef arch_ptrace_stop_needed
 325 /**
 326  * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
 327  * @code:       current->exit_code value ptrace will stop with
 328  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
 329  *
 330  * This is called with the siglock held, to decide whether or not it's
 331  * necessary to release the siglock and call arch_ptrace_stop() with the
 332  * same @code and @info arguments.  It can be defined to a constant if
 333  * arch_ptrace_stop() is never required, or always is.  On machines where
 334  * this makes sense, it should be defined to a quick test to optimize out
 335  * calling arch_ptrace_stop() when it would be superfluous.  For example,
 336  * if the thread has not been back to user mode since the last stop, the
 337  * thread state might indicate that nothing needs to be done.
 338  *
 339  * This is guaranteed to be invoked once before a task stops for ptrace and
 340  * may include arch-specific operations necessary prior to a ptrace stop.
 341  */
 342 #define arch_ptrace_stop_needed(code, info)     (0)
 343 #endif
 344
 345 #ifndef arch_ptrace_stop
 346 /**
 347  * arch_ptrace_stop - Do machine-specific work before stopping for ptrace
 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 no locks held when arch_ptrace_stop_needed() has
 352  * just returned nonzero.  It is allowed to block, e.g. for user memory
 353  * access.  The arch can have machine-specific work to be done before
 354  * ptrace stops.  On ia64, register backing store gets written back to user
 355  * memory here.  Since this can be costly (requires dropping the siglock),
 356  * we only do it when the arch requires it for this particular stop, as
 357  * indicated by arch_ptrace_stop_needed().
 358  */
 359 #define arch_ptrace_stop(code, info)            do { } while (0)
 360 #endif
 361
 362 #ifndef current_pt_regs
 363 #define current_pt_regs() task_pt_regs(current)
 364 #endif
 365
 366 #ifndef ptrace_signal_deliver
 367 #define ptrace_signal_deliver() ((void)0)
 368 #endif
 369
 370 /*
 371  * unlike current_pt_regs(), this one is equal to task_pt_regs(current)
 372  * on *all* architectures; the only reason to have a per-arch definition
 373  * is optimisation.
 374  */
 375 #ifndef signal_pt_regs
 376 #define signal_pt_regs() task_pt_regs(current)
 377 #endif
 378
 379 #ifndef current_user_stack_pointer
 380 #define current_user_stack_pointer() user_stack_pointer(current_pt_regs())
 381 #endif
 382
 383 extern int task_current_syscall(struct task_struct *target, long *callno,
 384                                 unsigned long args[6], unsigned int maxargs,
 385                                 unsigned long *sp, unsigned long *pc);
 386
 387 #endif