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 <uapi/linux/ptrace.h>
   9
  10 /*
  11  * Ptrace flags
  12  *
  13  * The owner ship rules for task->ptrace which holds the ptrace
  14  * flags is simple.  When a task is running it owns it's task->ptrace
  15  * flags.  When the a task is stopped the ptracer owns task->ptrace.
  16  */
  17
  18 #define PT_SEIZED       0x00010000      /* SEIZE used, enable new behavior */
  19 #define PT_PTRACED      0x00000001
  20 #define PT_DTRACE       0x00000002      /* delayed trace (used on m68k, i386) */
  21 #define PT_PTRACE_CAP   0x00000004      /* ptracer can follow suid-exec */
  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
  37 /* single stepping state bits (used on ARM and PA-RISC) */
  38 #define PT_SINGLESTEP_BIT       31
  39 #define PT_SINGLESTEP           (1<<PT_SINGLESTEP_BIT)
  40 #define PT_BLOCKSTEP_BIT        30
  41 #define PT_BLOCKSTEP            (1<<PT_BLOCKSTEP_BIT)
  42
  43 extern long arch_ptrace(struct task_struct *child, long request,
  44                         unsigned long addr, unsigned long data);
  45 extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);
  46 extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len);
  47 extern void ptrace_disable(struct task_struct *);
  48 extern int ptrace_request(struct task_struct *child, long request,
  49                           unsigned long addr, unsigned long data);
  50 extern void ptrace_notify(int exit_code);
  51 extern void __ptrace_link(struct task_struct *child,
  52                           struct task_struct *new_parent);
  53 extern void __ptrace_unlink(struct task_struct *child);
  54 extern void exit_ptrace(struct task_struct *tracer);
  55 #define PTRACE_MODE_READ        0x01
  56 #define PTRACE_MODE_ATTACH      0x02
  57 #define PTRACE_MODE_NOAUDIT     0x04
  58 /* Returns true on success, false on denial. */
  59 extern bool ptrace_may_access(struct task_struct *task, unsigned int mode);
  60
  61 static inline int ptrace_reparented(struct task_struct *child)
  62 {
  63         return !same_thread_group(child->real_parent, child->parent);
  64 }
  65
  66 static inline void ptrace_unlink(struct task_struct *child)
  67 {
  68         if (unlikely(child->ptrace))
  69                 __ptrace_unlink(child);
  70 }
  71
  72 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
  73                             unsigned long data);
  74 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
  75                             unsigned long data);
  76
  77 /**
  78  * ptrace_parent - return the task that is tracing the given task
  79  * @task: task to consider
  80  *
  81  * Returns %NULL if no one is tracing @task, or the &struct task_struct
  82  * pointer to its tracer.
  83  *
  84  * Must called under rcu_read_lock().  The pointer returned might be kept
  85  * live only by RCU.  During exec, this may be called with task_lock() held
  86  * on @task, still held from when check_unsafe_exec() was called.
  87  */
  88 static inline struct task_struct *ptrace_parent(struct task_struct *task)
  89 {
  90         if (unlikely(task->ptrace))
  91                 return rcu_dereference(task->parent);
  92         return NULL;
  93 }
  94
  95 /**
  96  * ptrace_event_enabled - test whether a ptrace event is enabled
  97  * @task: ptracee of interest
  98  * @event: %PTRACE_EVENT_* to test
  99  *
 100  * Test whether @event is enabled for ptracee @task.
 101  *
 102  * Returns %true if @event is enabled, %false otherwise.
 103  */
 104 static inline bool ptrace_event_enabled(struct task_struct *task, int event)
 105 {
 106         return task->ptrace & PT_EVENT_FLAG(event);
 107 }
 108
 109 /**
 110  * ptrace_event - possibly stop for a ptrace event notification
 111  * @event:      %PTRACE_EVENT_* value to report
 112  * @message:    value for %PTRACE_GETEVENTMSG to return
 113  *
 114  * Check whether @event is enabled and, if so, report @event and @message
 115  * to the ptrace parent.
 116  *
 117  * Called without locks.
 118  */
 119 static inline void ptrace_event(int event, unsigned long message)
 120 {
 121         if (unlikely(ptrace_event_enabled(current, event))) {
 122                 current->ptrace_message = message;
 123                 ptrace_notify((event << 8) | SIGTRAP);
 124         } else if (event == PTRACE_EVENT_EXEC) {
 125                 /* legacy EXEC report via SIGTRAP */
 126                 if ((current->ptrace & (PT_PTRACED|PT_SEIZED)) == PT_PTRACED)
 127                         send_sig(SIGTRAP, current, 0);
 128         }
 129 }
 130
 131 /**
 132  * ptrace_init_task - initialize ptrace state for a new child
 133  * @child:              new child task
 134  * @ptrace:             true if child should be ptrace'd by parent's tracer
 135  *
 136  * This is called immediately after adding @child to its parent's children
 137  * list.  @ptrace is false in the normal case, and true to ptrace @child.
 138  *
 139  * Called with current's siglock and write_lock_irq(&tasklist_lock) held.
 140  */
 141 static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
 142 {
 143         INIT_LIST_HEAD(&child->ptrace_entry);
 144         INIT_LIST_HEAD(&child->ptraced);
 145 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 146         atomic_set(&child->ptrace_bp_refcnt, 1);
 147 #endif
 148         child->jobctl = 0;
 149         child->ptrace = 0;
 150         child->parent = child->real_parent;
 151
 152         if (unlikely(ptrace) && current->ptrace) {
 153                 child->ptrace = current->ptrace;
 154                 __ptrace_link(child, current->parent);
 155
 156                 if (child->ptrace & PT_SEIZED)
 157                         task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
 158                 else
 159                         sigaddset(&child->pending.signal, SIGSTOP);
 160
 161                 set_tsk_thread_flag(child, TIF_SIGPENDING);
 162         }
 163 }
 164
 165 /**
 166  * ptrace_release_task - final ptrace-related cleanup of a zombie being reaped
 167  * @task:       task in %EXIT_DEAD state
 168  *
 169  * Called with write_lock(&tasklist_lock) held.
 170  */
 171 static inline void ptrace_release_task(struct task_struct *task)
 172 {
 173         BUG_ON(!list_empty(&task->ptraced));
 174         ptrace_unlink(task);
 175         BUG_ON(!list_empty(&task->ptrace_entry));
 176 }
 177
 178 #ifndef force_successful_syscall_return
 179 /*
 180  * System call handlers that, upon successful completion, need to return a
 181  * negative value should call force_successful_syscall_return() right before
 182  * returning.  On architectures where the syscall convention provides for a
 183  * separate error flag (e.g., alpha, ia64, ppc{,64}, sparc{,64}, possibly
 184  * others), this macro can be used to ensure that the error flag will not get
 185  * set.  On architectures which do not support a separate error flag, the macro
 186  * is a no-op and the spurious error condition needs to be filtered out by some
 187  * other means (e.g., in user-level, by passing an extra argument to the
 188  * syscall handler, or something along those lines).
 189  */
 190 #define force_successful_syscall_return() do { } while (0)
 191 #endif
 192
 193 #ifndef is_syscall_success
 194 /*
 195  * On most systems we can tell if a syscall is a success based on if the retval
 196  * is an error value.  On some systems like ia64 and powerpc they have different
 197  * indicators of success/failure and must define their own.
 198  */
 199 #define is_syscall_success(regs) (!IS_ERR_VALUE((unsigned long)(regs_return_value(regs))))
 200 #endif
 201
 202 /*
 203  * <asm/ptrace.h> should define the following things inside #ifdef __KERNEL__.
 204  *
 205  * These do-nothing inlines are used when the arch does not
 206  * implement single-step.  The kerneldoc comments are here
 207  * to document the interface for all arch definitions.
 208  */
 209
 210 #ifndef arch_has_single_step
 211 /**
 212  * arch_has_single_step - does this CPU support user-mode single-step?
 213  *
 214  * If this is defined, then there must be function declarations or
 215  * inlines for user_enable_single_step() and user_disable_single_step().
 216  * arch_has_single_step() should evaluate to nonzero iff the machine
 217  * supports instruction single-step for user mode.
 218  * It can be a constant or it can test a CPU feature bit.
 219  */
 220 #define arch_has_single_step()          (0)
 221
 222 /**
 223  * user_enable_single_step - single-step in user-mode task
 224  * @task: either current or a task stopped in %TASK_TRACED
 225  *
 226  * This can only be called when arch_has_single_step() has returned nonzero.
 227  * Set @task so that when it returns to user mode, it will trap after the
 228  * next single instruction executes.  If arch_has_block_step() is defined,
 229  * this must clear the effects of user_enable_block_step() too.
 230  */
 231 static inline void user_enable_single_step(struct task_struct *task)
 232 {
 233         BUG();                  /* This can never be called.  */
 234 }
 235
 236 /**
 237  * user_disable_single_step - cancel user-mode single-step
 238  * @task: either current or a task stopped in %TASK_TRACED
 239  *
 240  * Clear @task of the effects of user_enable_single_step() and
 241  * user_enable_block_step().  This can be called whether or not either
 242  * of those was ever called on @task, and even if arch_has_single_step()
 243  * returned zero.
 244  */
 245 static inline void user_disable_single_step(struct task_struct *task)
 246 {
 247 }
 248 #else
 249 extern void user_enable_single_step(struct task_struct *);
 250 extern void user_disable_single_step(struct task_struct *);
 251 #endif  /* arch_has_single_step */
 252
 253 #ifndef arch_has_block_step
 254 /**
 255  * arch_has_block_step - does this CPU support user-mode block-step?
 256  *
 257  * If this is defined, then there must be a function declaration or inline
 258  * for user_enable_block_step(), and arch_has_single_step() must be defined
 259  * too.  arch_has_block_step() should evaluate to nonzero iff the machine
 260  * supports step-until-branch for user mode.  It can be a constant or it
 261  * can test a CPU feature bit.
 262  */
 263 #define arch_has_block_step()           (0)
 264
 265 /**
 266  * user_enable_block_step - step until branch in user-mode task
 267  * @task: either current or a task stopped in %TASK_TRACED
 268  *
 269  * This can only be called when arch_has_block_step() has returned nonzero,
 270  * and will never be called when single-instruction stepping is being used.
 271  * Set @task so that when it returns to user mode, it will trap after the
 272  * next branch or trap taken.
 273  */
 274 static inline void user_enable_block_step(struct task_struct *task)
 275 {
 276         BUG();                  /* This can never be called.  */
 277 }
 278 #else
 279 extern void user_enable_block_step(struct task_struct *);
 280 #endif  /* arch_has_block_step */
 281
 282 #ifdef ARCH_HAS_USER_SINGLE_STEP_INFO
 283 extern void user_single_step_siginfo(struct task_struct *tsk,
 284                                 struct pt_regs *regs, siginfo_t *info);
 285 #else
 286 static inline void user_single_step_siginfo(struct task_struct *tsk,
 287                                 struct pt_regs *regs, siginfo_t *info)
 288 {
 289         memset(info, 0, sizeof(*info));
 290         info->si_signo = SIGTRAP;
 291 }
 292 #endif
 293
 294 #ifndef arch_ptrace_stop_needed
 295 /**
 296  * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
 297  * @code:       current->exit_code value ptrace will stop with
 298  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
 299  *
 300  * This is called with the siglock held, to decide whether or not it's
 301  * necessary to release the siglock and call arch_ptrace_stop() with the
 302  * same @code and @info arguments.  It can be defined to a constant if
 303  * arch_ptrace_stop() is never required, or always is.  On machines where
 304  * this makes sense, it should be defined to a quick test to optimize out
 305  * calling arch_ptrace_stop() when it would be superfluous.  For example,
 306  * if the thread has not been back to user mode since the last stop, the
 307  * thread state might indicate that nothing needs to be done.
 308  */
 309 #define arch_ptrace_stop_needed(code, info)     (0)
 310 #endif
 311
 312 #ifndef arch_ptrace_stop
 313 /**
 314  * arch_ptrace_stop - Do machine-specific work before stopping for ptrace
 315  * @code:       current->exit_code value ptrace will stop with
 316  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
 317  *
 318  * This is called with no locks held when arch_ptrace_stop_needed() has
 319  * just returned nonzero.  It is allowed to block, e.g. for user memory
 320  * access.  The arch can have machine-specific work to be done before
 321  * ptrace stops.  On ia64, register backing store gets written back to user
 322  * memory here.  Since this can be costly (requires dropping the siglock),
 323  * we only do it when the arch requires it for this particular stop, as
 324  * indicated by arch_ptrace_stop_needed().
 325  */
 326 #define arch_ptrace_stop(code, info)            do { } while (0)
 327 #endif
 328
 329 #ifndef current_pt_regs
 330 #define current_pt_regs() task_pt_regs(current)
 331 #endif
 332
 333 #ifndef ptrace_signal_deliver
 334 #define ptrace_signal_deliver() ((void)0)
 335 #endif
 336
 337 /*
 338  * unlike current_pt_regs(), this one is equal to task_pt_regs(current)
 339  * on *all* architectures; the only reason to have a per-arch definition
 340  * is optimisation.
 341  */
 342 #ifndef signal_pt_regs
 343 #define signal_pt_regs() task_pt_regs(current)
 344 #endif
 345
 346 #ifndef current_user_stack_pointer
 347 #define current_user_stack_pointer() user_stack_pointer(current_pt_regs())
 348 #endif
 349
 350 extern int task_current_syscall(struct task_struct *target, long *callno,
 351                                 unsigned long args[6], unsigned int maxargs,
 352                                 unsigned long *sp, unsigned long *pc);
 353
 354 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 355 extern int ptrace_get_breakpoints(struct task_struct *tsk);
 356 extern void ptrace_put_breakpoints(struct task_struct *tsk);
 357 #else
 358 static inline void ptrace_put_breakpoints(struct task_struct *tsk) { }
 359 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
 360
 361 #endif