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 #define PTRACE_MODE_FSCREDS 0x08
  61 #define PTRACE_MODE_REALCREDS 0x10
  62
  63 /* shorthands for READ/ATTACH and FSCREDS/REALCREDS combinations */
  64 #define PTRACE_MODE_READ_FSCREDS (PTRACE_MODE_READ | PTRACE_MODE_FSCREDS)
  65 #define PTRACE_MODE_READ_REALCREDS (PTRACE_MODE_READ | PTRACE_MODE_REALCREDS)
  66 #define PTRACE_MODE_ATTACH_FSCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_FSCREDS)
  67 #define PTRACE_MODE_ATTACH_REALCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_REALCREDS)
  68
  69 /**
  70  * ptrace_may_access - check whether the caller is permitted to access
  71  * a target task.
  72  * @task: target task
  73  * @mode: selects type of access and caller credentials
  74  *
  75  * Returns true on success, false on denial.
  76  *
  77  * One of the flags PTRACE_MODE_FSCREDS and PTRACE_MODE_REALCREDS must
  78  * be set in @mode to specify whether the access was requested through
  79  * a filesystem syscall (should use effective capabilities and fsuid
  80  * of the caller) or through an explicit syscall such as
  81  * process_vm_writev or ptrace (and should use the real credentials).
  82  */
  83 extern bool ptrace_may_access(struct task_struct *task, unsigned int mode);
  84
  85 static inline int ptrace_reparented(struct task_struct *child)
  86 {
  87         return !same_thread_group(child->real_parent, child->parent);
  88 }
  89
  90 static inline void ptrace_unlink(struct task_struct *child)
  91 {
  92         if (unlikely(child->ptrace))
  93                 __ptrace_unlink(child);
  94 }
  95
  96 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
  97                             unsigned long data);
  98 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
  99                             unsigned long data);
 100
 101 /**
 102  * ptrace_parent - return the task that is tracing the given task
 103  * @task: task to consider
 104  *
 105  * Returns %NULL if no one is tracing @task, or the &struct task_struct
 106  * pointer to its tracer.
 107  *
 108  * Must called under rcu_read_lock().  The pointer returned might be kept
 109  * live only by RCU.  During exec, this may be called with task_lock() held
 110  * on @task, still held from when check_unsafe_exec() was called.
 111  */
 112 static inline struct task_struct *ptrace_parent(struct task_struct *task)
 113 {
 114         if (unlikely(task->ptrace))
 115                 return rcu_dereference(task->parent);
 116         return NULL;
 117 }
 118
 119 /**
 120  * ptrace_event_enabled - test whether a ptrace event is enabled
 121  * @task: ptracee of interest
 122  * @event: %PTRACE_EVENT_* to test
 123  *
 124  * Test whether @event is enabled for ptracee @task.
 125  *
 126  * Returns %true if @event is enabled, %false otherwise.
 127  */
 128 static inline bool ptrace_event_enabled(struct task_struct *task, int event)
 129 {
 130         return task->ptrace & PT_EVENT_FLAG(event);
 131 }
 132
 133 /**
 134  * ptrace_event - possibly stop for a ptrace event notification
 135  * @event:      %PTRACE_EVENT_* value to report
 136  * @message:    value for %PTRACE_GETEVENTMSG to return
 137  *
 138  * Check whether @event is enabled and, if so, report @event and @message
 139  * to the ptrace parent.
 140  *
 141  * Called without locks.
 142  */
 143 static inline void ptrace_event(int event, unsigned long message)
 144 {
 145         if (unlikely(ptrace_event_enabled(current, event))) {
 146                 current->ptrace_message = message;
 147                 ptrace_notify((event << 8) | SIGTRAP);
 148         } else if (event == PTRACE_EVENT_EXEC) {
 149                 /* legacy EXEC report via SIGTRAP */
 150                 if ((current->ptrace & (PT_PTRACED|PT_SEIZED)) == PT_PTRACED)
 151                         send_sig(SIGTRAP, current, 0);
 152         }
 153 }
 154
 155 /**
 156  * ptrace_event_pid - possibly stop for a ptrace event notification
 157  * @event:      %PTRACE_EVENT_* value to report
 158  * @pid:        process identifier for %PTRACE_GETEVENTMSG to return
 159  *
 160  * Check whether @event is enabled and, if so, report @event and @pid
 161  * to the ptrace parent.  @pid is reported as the pid_t seen from the
 162  * the ptrace parent's pid namespace.
 163  *
 164  * Called without locks.
 165  */
 166 static inline void ptrace_event_pid(int event, struct pid *pid)
 167 {
 168         /*
 169          * FIXME: There's a potential race if a ptracer in a different pid
 170          * namespace than parent attaches between computing message below and
 171          * when we acquire tasklist_lock in ptrace_stop().  If this happens,
 172          * the ptracer will get a bogus pid from PTRACE_GETEVENTMSG.
 173          */
 174         unsigned long message = 0;
 175         struct pid_namespace *ns;
 176
 177         rcu_read_lock();
 178         ns = task_active_pid_ns(rcu_dereference(current->parent));
 179         if (ns)
 180                 message = pid_nr_ns(pid, ns);
 181         rcu_read_unlock();
 182
 183         ptrace_event(event, message);
 184 }
 185
 186 /**
 187  * ptrace_init_task - initialize ptrace state for a new child
 188  * @child:              new child task
 189  * @ptrace:             true if child should be ptrace'd by parent's tracer
 190  *
 191  * This is called immediately after adding @child to its parent's children
 192  * list.  @ptrace is false in the normal case, and true to ptrace @child.
 193  *
 194  * Called with current's siglock and write_lock_irq(&tasklist_lock) held.
 195  */
 196 static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
 197 {
 198         INIT_LIST_HEAD(&child->ptrace_entry);
 199         INIT_LIST_HEAD(&child->ptraced);
 200         child->jobctl = 0;
 201         child->ptrace = 0;
 202         child->parent = child->real_parent;
 203
 204         if (unlikely(ptrace) && current->ptrace) {
 205                 child->ptrace = current->ptrace;
 206                 __ptrace_link(child, current->parent);
 207
 208                 if (child->ptrace & PT_SEIZED)
 209                         task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
 210                 else
 211                         sigaddset(&child->pending.signal, SIGSTOP);
 212
 213                 set_tsk_thread_flag(child, TIF_SIGPENDING);
 214         }
 215 }
 216
 217 /**
 218  * ptrace_release_task - final ptrace-related cleanup of a zombie being reaped
 219  * @task:       task in %EXIT_DEAD state
 220  *
 221  * Called with write_lock(&tasklist_lock) held.
 222  */
 223 static inline void ptrace_release_task(struct task_struct *task)
 224 {
 225         BUG_ON(!list_empty(&task->ptraced));
 226         ptrace_unlink(task);
 227         BUG_ON(!list_empty(&task->ptrace_entry));
 228 }
 229
 230 #ifndef force_successful_syscall_return
 231 /*
 232  * System call handlers that, upon successful completion, need to return a
 233  * negative value should call force_successful_syscall_return() right before
 234  * returning.  On architectures where the syscall convention provides for a
 235  * separate error flag (e.g., alpha, ia64, ppc{,64}, sparc{,64}, possibly
 236  * others), this macro can be used to ensure that the error flag will not get
 237  * set.  On architectures which do not support a separate error flag, the macro
 238  * is a no-op and the spurious error condition needs to be filtered out by some
 239  * other means (e.g., in user-level, by passing an extra argument to the
 240  * syscall handler, or something along those lines).
 241  */
 242 #define force_successful_syscall_return() do { } while (0)
 243 #endif
 244
 245 #ifndef is_syscall_success
 246 /*
 247  * On most systems we can tell if a syscall is a success based on if the retval
 248  * is an error value.  On some systems like ia64 and powerpc they have different
 249  * indicators of success/failure and must define their own.
 250  */
 251 #define is_syscall_success(regs) (!IS_ERR_VALUE((unsigned long)(regs_return_value(regs))))
 252 #endif
 253
 254 /*
 255  * <asm/ptrace.h> should define the following things inside #ifdef __KERNEL__.
 256  *
 257  * These do-nothing inlines are used when the arch does not
 258  * implement single-step.  The kerneldoc comments are here
 259  * to document the interface for all arch definitions.
 260  */
 261
 262 #ifndef arch_has_single_step
 263 /**
 264  * arch_has_single_step - does this CPU support user-mode single-step?
 265  *
 266  * If this is defined, then there must be function declarations or
 267  * inlines for user_enable_single_step() and user_disable_single_step().
 268  * arch_has_single_step() should evaluate to nonzero iff the machine
 269  * supports instruction single-step for user mode.
 270  * It can be a constant or it can test a CPU feature bit.
 271  */
 272 #define arch_has_single_step()          (0)
 273
 274 /**
 275  * user_enable_single_step - single-step in user-mode task
 276  * @task: either current or a task stopped in %TASK_TRACED
 277  *
 278  * This can only be called when arch_has_single_step() has returned nonzero.
 279  * Set @task so that when it returns to user mode, it will trap after the
 280  * next single instruction executes.  If arch_has_block_step() is defined,
 281  * this must clear the effects of user_enable_block_step() too.
 282  */
 283 static inline void user_enable_single_step(struct task_struct *task)
 284 {
 285         BUG();                  /* This can never be called.  */
 286 }
 287
 288 /**
 289  * user_disable_single_step - cancel user-mode single-step
 290  * @task: either current or a task stopped in %TASK_TRACED
 291  *
 292  * Clear @task of the effects of user_enable_single_step() and
 293  * user_enable_block_step().  This can be called whether or not either
 294  * of those was ever called on @task, and even if arch_has_single_step()
 295  * returned zero.
 296  */
 297 static inline void user_disable_single_step(struct task_struct *task)
 298 {
 299 }
 300 #else
 301 extern void user_enable_single_step(struct task_struct *);
 302 extern void user_disable_single_step(struct task_struct *);
 303 #endif  /* arch_has_single_step */
 304
 305 #ifndef arch_has_block_step
 306 /**
 307  * arch_has_block_step - does this CPU support user-mode block-step?
 308  *
 309  * If this is defined, then there must be a function declaration or inline
 310  * for user_enable_block_step(), and arch_has_single_step() must be defined
 311  * too.  arch_has_block_step() should evaluate to nonzero iff the machine
 312  * supports step-until-branch for user mode.  It can be a constant or it
 313  * can test a CPU feature bit.
 314  */
 315 #define arch_has_block_step()           (0)
 316
 317 /**
 318  * user_enable_block_step - step until branch in user-mode task
 319  * @task: either current or a task stopped in %TASK_TRACED
 320  *
 321  * This can only be called when arch_has_block_step() has returned nonzero,
 322  * and will never be called when single-instruction stepping is being used.
 323  * Set @task so that when it returns to user mode, it will trap after the
 324  * next branch or trap taken.
 325  */
 326 static inline void user_enable_block_step(struct task_struct *task)
 327 {
 328         BUG();                  /* This can never be called.  */
 329 }
 330 #else
 331 extern void user_enable_block_step(struct task_struct *);
 332 #endif  /* arch_has_block_step */
 333
 334 #ifdef ARCH_HAS_USER_SINGLE_STEP_INFO
 335 extern void user_single_step_siginfo(struct task_struct *tsk,
 336                                 struct pt_regs *regs, siginfo_t *info);
 337 #else
 338 static inline void user_single_step_siginfo(struct task_struct *tsk,
 339                                 struct pt_regs *regs, siginfo_t *info)
 340 {
 341         memset(info, 0, sizeof(*info));
 342         info->si_signo = SIGTRAP;
 343 }
 344 #endif
 345
 346 #ifndef arch_ptrace_stop_needed
 347 /**
 348  * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
 349  * @code:       current->exit_code value ptrace will stop with
 350  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
 351  *
 352  * This is called with the siglock held, to decide whether or not it's
 353  * necessary to release the siglock and call arch_ptrace_stop() with the
 354  * same @code and @info arguments.  It can be defined to a constant if
 355  * arch_ptrace_stop() is never required, or always is.  On machines where
 356  * this makes sense, it should be defined to a quick test to optimize out
 357  * calling arch_ptrace_stop() when it would be superfluous.  For example,
 358  * if the thread has not been back to user mode since the last stop, the
 359  * thread state might indicate that nothing needs to be done.
 360  *
 361  * This is guaranteed to be invoked once before a task stops for ptrace and
 362  * may include arch-specific operations necessary prior to a ptrace stop.
 363  */
 364 #define arch_ptrace_stop_needed(code, info)     (0)
 365 #endif
 366
 367 #ifndef arch_ptrace_stop
 368 /**
 369  * arch_ptrace_stop - Do machine-specific work before stopping for ptrace
 370  * @code:       current->exit_code value ptrace will stop with
 371  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
 372  *
 373  * This is called with no locks held when arch_ptrace_stop_needed() has
 374  * just returned nonzero.  It is allowed to block, e.g. for user memory
 375  * access.  The arch can have machine-specific work to be done before
 376  * ptrace stops.  On ia64, register backing store gets written back to user
 377  * memory here.  Since this can be costly (requires dropping the siglock),
 378  * we only do it when the arch requires it for this particular stop, as
 379  * indicated by arch_ptrace_stop_needed().
 380  */
 381 #define arch_ptrace_stop(code, info)            do { } while (0)
 382 #endif
 383
 384 #ifndef current_pt_regs
 385 #define current_pt_regs() task_pt_regs(current)
 386 #endif
 387
 388 #ifndef ptrace_signal_deliver
 389 #define ptrace_signal_deliver() ((void)0)
 390 #endif
 391
 392 /*
 393  * unlike current_pt_regs(), this one is equal to task_pt_regs(current)
 394  * on *all* architectures; the only reason to have a per-arch definition
 395  * is optimisation.
 396  */
 397 #ifndef signal_pt_regs
 398 #define signal_pt_regs() task_pt_regs(current)
 399 #endif
 400
 401 #ifndef current_user_stack_pointer
 402 #define current_user_stack_pointer() user_stack_pointer(current_pt_regs())
 403 #endif
 404
 405 extern int task_current_syscall(struct task_struct *target, long *callno,
 406                                 unsigned long args[6], unsigned int maxargs,
 407                                 unsigned long *sp, unsigned long *pc);
 408
 409 #endif