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);
  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 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 178         atomic_set(&child->ptrace_bp_refcnt, 1);
 179 #endif
 180         child->jobctl = 0;
 181         child->ptrace = 0;
 182         child->parent = child->real_parent;
 183
 184         if (unlikely(ptrace) && current->ptrace) {
 185                 child->ptrace = current->ptrace;
 186                 __ptrace_link(child, current->parent);
 187
 188                 if (child->ptrace & PT_SEIZED)
 189                         task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
 190                 else
 191                         sigaddset(&child->pending.signal, SIGSTOP);
 192
 193                 set_tsk_thread_flag(child, TIF_SIGPENDING);
 194         }
 195 }
 196
 197 /**
 198  * ptrace_release_task - final ptrace-related cleanup of a zombie being reaped
 199  * @task:       task in %EXIT_DEAD state
 200  *
 201  * Called with write_lock(&tasklist_lock) held.
 202  */
 203 static inline void ptrace_release_task(struct task_struct *task)
 204 {
 205         BUG_ON(!list_empty(&task->ptraced));
 206         ptrace_unlink(task);
 207         BUG_ON(!list_empty(&task->ptrace_entry));
 208 }
 209
 210 #ifndef force_successful_syscall_return
 211 /*
 212  * System call handlers that, upon successful completion, need to return a
 213  * negative value should call force_successful_syscall_return() right before
 214  * returning.  On architectures where the syscall convention provides for a
 215  * separate error flag (e.g., alpha, ia64, ppc{,64}, sparc{,64}, possibly
 216  * others), this macro can be used to ensure that the error flag will not get
 217  * set.  On architectures which do not support a separate error flag, the macro
 218  * is a no-op and the spurious error condition needs to be filtered out by some
 219  * other means (e.g., in user-level, by passing an extra argument to the
 220  * syscall handler, or something along those lines).
 221  */
 222 #define force_successful_syscall_return() do { } while (0)
 223 #endif
 224
 225 #ifndef is_syscall_success
 226 /*
 227  * On most systems we can tell if a syscall is a success based on if the retval
 228  * is an error value.  On some systems like ia64 and powerpc they have different
 229  * indicators of success/failure and must define their own.
 230  */
 231 #define is_syscall_success(regs) (!IS_ERR_VALUE((unsigned long)(regs_return_value(regs))))
 232 #endif
 233
 234 /*
 235  * <asm/ptrace.h> should define the following things inside #ifdef __KERNEL__.
 236  *
 237  * These do-nothing inlines are used when the arch does not
 238  * implement single-step.  The kerneldoc comments are here
 239  * to document the interface for all arch definitions.
 240  */
 241
 242 #ifndef arch_has_single_step
 243 /**
 244  * arch_has_single_step - does this CPU support user-mode single-step?
 245  *
 246  * If this is defined, then there must be function declarations or
 247  * inlines for user_enable_single_step() and user_disable_single_step().
 248  * arch_has_single_step() should evaluate to nonzero iff the machine
 249  * supports instruction single-step for user mode.
 250  * It can be a constant or it can test a CPU feature bit.
 251  */
 252 #define arch_has_single_step()          (0)
 253
 254 /**
 255  * user_enable_single_step - single-step in user-mode task
 256  * @task: either current or a task stopped in %TASK_TRACED
 257  *
 258  * This can only be called when arch_has_single_step() has returned nonzero.
 259  * Set @task so that when it returns to user mode, it will trap after the
 260  * next single instruction executes.  If arch_has_block_step() is defined,
 261  * this must clear the effects of user_enable_block_step() too.
 262  */
 263 static inline void user_enable_single_step(struct task_struct *task)
 264 {
 265         BUG();                  /* This can never be called.  */
 266 }
 267
 268 /**
 269  * user_disable_single_step - cancel user-mode single-step
 270  * @task: either current or a task stopped in %TASK_TRACED
 271  *
 272  * Clear @task of the effects of user_enable_single_step() and
 273  * user_enable_block_step().  This can be called whether or not either
 274  * of those was ever called on @task, and even if arch_has_single_step()
 275  * returned zero.
 276  */
 277 static inline void user_disable_single_step(struct task_struct *task)
 278 {
 279 }
 280 #else
 281 extern void user_enable_single_step(struct task_struct *);
 282 extern void user_disable_single_step(struct task_struct *);
 283 #endif  /* arch_has_single_step */
 284
 285 #ifndef arch_has_block_step
 286 /**
 287  * arch_has_block_step - does this CPU support user-mode block-step?
 288  *
 289  * If this is defined, then there must be a function declaration or inline
 290  * for user_enable_block_step(), and arch_has_single_step() must be defined
 291  * too.  arch_has_block_step() should evaluate to nonzero iff the machine
 292  * supports step-until-branch for user mode.  It can be a constant or it
 293  * can test a CPU feature bit.
 294  */
 295 #define arch_has_block_step()           (0)
 296
 297 /**
 298  * user_enable_block_step - step until branch in user-mode task
 299  * @task: either current or a task stopped in %TASK_TRACED
 300  *
 301  * This can only be called when arch_has_block_step() has returned nonzero,
 302  * and will never be called when single-instruction stepping is being used.
 303  * Set @task so that when it returns to user mode, it will trap after the
 304  * next branch or trap taken.
 305  */
 306 static inline void user_enable_block_step(struct task_struct *task)
 307 {
 308         BUG();                  /* This can never be called.  */
 309 }
 310 #else
 311 extern void user_enable_block_step(struct task_struct *);
 312 #endif  /* arch_has_block_step */
 313
 314 #ifdef ARCH_HAS_USER_SINGLE_STEP_INFO
 315 extern void user_single_step_siginfo(struct task_struct *tsk,
 316                                 struct pt_regs *regs, siginfo_t *info);
 317 #else
 318 static inline void user_single_step_siginfo(struct task_struct *tsk,
 319                                 struct pt_regs *regs, siginfo_t *info)
 320 {
 321         memset(info, 0, sizeof(*info));
 322         info->si_signo = SIGTRAP;
 323 }
 324 #endif
 325
 326 #ifndef arch_ptrace_stop_needed
 327 /**
 328  * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
 329  * @code:       current->exit_code value ptrace will stop with
 330  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
 331  *
 332  * This is called with the siglock held, to decide whether or not it's
 333  * necessary to release the siglock and call arch_ptrace_stop() with the
 334  * same @code and @info arguments.  It can be defined to a constant if
 335  * arch_ptrace_stop() is never required, or always is.  On machines where
 336  * this makes sense, it should be defined to a quick test to optimize out
 337  * calling arch_ptrace_stop() when it would be superfluous.  For example,
 338  * if the thread has not been back to user mode since the last stop, the
 339  * thread state might indicate that nothing needs to be done.
 340  *
 341  * This is guaranteed to be invoked once before a task stops for ptrace and
 342  * may include arch-specific operations necessary prior to a ptrace stop.
 343  */
 344 #define arch_ptrace_stop_needed(code, info)     (0)
 345 #endif
 346
 347 #ifndef arch_ptrace_stop
 348 /**
 349  * arch_ptrace_stop - Do machine-specific work before stopping for ptrace
 350  * @code:       current->exit_code value ptrace will stop with
 351  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
 352  *
 353  * This is called with no locks held when arch_ptrace_stop_needed() has
 354  * just returned nonzero.  It is allowed to block, e.g. for user memory
 355  * access.  The arch can have machine-specific work to be done before
 356  * ptrace stops.  On ia64, register backing store gets written back to user
 357  * memory here.  Since this can be costly (requires dropping the siglock),
 358  * we only do it when the arch requires it for this particular stop, as
 359  * indicated by arch_ptrace_stop_needed().
 360  */
 361 #define arch_ptrace_stop(code, info)            do { } while (0)
 362 #endif
 363
 364 #ifndef current_pt_regs
 365 #define current_pt_regs() task_pt_regs(current)
 366 #endif
 367
 368 #ifndef ptrace_signal_deliver
 369 #define ptrace_signal_deliver() ((void)0)
 370 #endif
 371
 372 /*
 373  * unlike current_pt_regs(), this one is equal to task_pt_regs(current)
 374  * on *all* architectures; the only reason to have a per-arch definition
 375  * is optimisation.
 376  */
 377 #ifndef signal_pt_regs
 378 #define signal_pt_regs() task_pt_regs(current)
 379 #endif
 380
 381 #ifndef current_user_stack_pointer
 382 #define current_user_stack_pointer() user_stack_pointer(current_pt_regs())
 383 #endif
 384
 385 extern int task_current_syscall(struct task_struct *target, long *callno,
 386                                 unsigned long args[6], unsigned int maxargs,
 387                                 unsigned long *sp, unsigned long *pc);
 388
 389 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 390 extern int ptrace_get_breakpoints(struct task_struct *tsk);
 391 extern void ptrace_put_breakpoints(struct task_struct *tsk);
 392 #else
 393 static inline void ptrace_put_breakpoints(struct task_struct *tsk) { }
 394 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
 395
 396 #endif