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 #define PTRACE_MODE_FSCREDS 0x08
  60 #define PTRACE_MODE_REALCREDS 0x10
  61
  62 /* shorthands for READ/ATTACH and FSCREDS/REALCREDS combinations */
  63 #define PTRACE_MODE_READ_FSCREDS (PTRACE_MODE_READ | PTRACE_MODE_FSCREDS)
  64 #define PTRACE_MODE_READ_REALCREDS (PTRACE_MODE_READ | PTRACE_MODE_REALCREDS)
  65 #define PTRACE_MODE_ATTACH_FSCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_FSCREDS)
  66 #define PTRACE_MODE_ATTACH_REALCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_REALCREDS)
  67
  68 /**
  69  * ptrace_may_access - check whether the caller is permitted to access
  70  * a target task.
  71  * @task: target task
  72  * @mode: selects type of access and caller credentials
  73  *
  74  * Returns true on success, false on denial.
  75  *
  76  * One of the flags PTRACE_MODE_FSCREDS and PTRACE_MODE_REALCREDS must
  77  * be set in @mode to specify whether the access was requested through
  78  * a filesystem syscall (should use effective capabilities and fsuid
  79  * of the caller) or through an explicit syscall such as
  80  * process_vm_writev or ptrace (and should use the real credentials).
  81  */
  82 extern bool ptrace_may_access(struct task_struct *task, unsigned int mode);
  83
  84 static inline int ptrace_reparented(struct task_struct *child)
  85 {
  86         return !same_thread_group(child->real_parent, child->parent);
  87 }
  88
  89 static inline void ptrace_unlink(struct task_struct *child)
  90 {
  91         if (unlikely(child->ptrace))
  92                 __ptrace_unlink(child);
  93 }
  94
  95 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
  96                             unsigned long data);
  97 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
  98                             unsigned long data);
  99
 100 /**
 101  * ptrace_parent - return the task that is tracing the given task
 102  * @task: task to consider
 103  *
 104  * Returns %NULL if no one is tracing @task, or the &struct task_struct
 105  * pointer to its tracer.
 106  *
 107  * Must called under rcu_read_lock().  The pointer returned might be kept
 108  * live only by RCU.  During exec, this may be called with task_lock() held
 109  * on @task, still held from when check_unsafe_exec() was called.
 110  */
 111 static inline struct task_struct *ptrace_parent(struct task_struct *task)
 112 {
 113         if (unlikely(task->ptrace))
 114                 return rcu_dereference(task->parent);
 115         return NULL;
 116 }
 117
 118 /**
 119  * ptrace_event_enabled - test whether a ptrace event is enabled
 120  * @task: ptracee of interest
 121  * @event: %PTRACE_EVENT_* to test
 122  *
 123  * Test whether @event is enabled for ptracee @task.
 124  *
 125  * Returns %true if @event is enabled, %false otherwise.
 126  */
 127 static inline bool ptrace_event_enabled(struct task_struct *task, int event)
 128 {
 129         return task->ptrace & PT_EVENT_FLAG(event);
 130 }
 131
 132 /**
 133  * ptrace_event - possibly stop for a ptrace event notification
 134  * @event:      %PTRACE_EVENT_* value to report
 135  * @message:    value for %PTRACE_GETEVENTMSG to return
 136  *
 137  * Check whether @event is enabled and, if so, report @event and @message
 138  * to the ptrace parent.
 139  *
 140  * Called without locks.
 141  */
 142 static inline void ptrace_event(int event, unsigned long message)
 143 {
 144         if (unlikely(ptrace_event_enabled(current, event))) {
 145                 current->ptrace_message = message;
 146                 ptrace_notify((event << 8) | SIGTRAP);
 147         } else if (event == PTRACE_EVENT_EXEC) {
 148                 /* legacy EXEC report via SIGTRAP */
 149                 if ((current->ptrace & (PT_PTRACED|PT_SEIZED)) == PT_PTRACED)
 150                         send_sig(SIGTRAP, current, 0);
 151         }
 152 }
 153
 154 /**
 155  * ptrace_event_pid - possibly stop for a ptrace event notification
 156  * @event:      %PTRACE_EVENT_* value to report
 157  * @pid:        process identifier for %PTRACE_GETEVENTMSG to return
 158  *
 159  * Check whether @event is enabled and, if so, report @event and @pid
 160  * to the ptrace parent.  @pid is reported as the pid_t seen from the
 161  * the ptrace parent's pid namespace.
 162  *
 163  * Called without locks.
 164  */
 165 static inline void ptrace_event_pid(int event, struct pid *pid)
 166 {
 167         /*
 168          * FIXME: There's a potential race if a ptracer in a different pid
 169          * namespace than parent attaches between computing message below and
 170          * when we acquire tasklist_lock in ptrace_stop().  If this happens,
 171          * the ptracer will get a bogus pid from PTRACE_GETEVENTMSG.
 172          */
 173         unsigned long message = 0;
 174         struct pid_namespace *ns;
 175
 176         rcu_read_lock();
 177         ns = task_active_pid_ns(rcu_dereference(current->parent));
 178         if (ns)
 179                 message = pid_nr_ns(pid, ns);
 180         rcu_read_unlock();
 181
 182         ptrace_event(event, message);
 183 }
 184
 185 /**
 186  * ptrace_init_task - initialize ptrace state for a new child
 187  * @child:              new child task
 188  * @ptrace:             true if child should be ptrace'd by parent's tracer
 189  *
 190  * This is called immediately after adding @child to its parent's children
 191  * list.  @ptrace is false in the normal case, and true to ptrace @child.
 192  *
 193  * Called with current's siglock and write_lock_irq(&tasklist_lock) held.
 194  */
 195 static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
 196 {
 197         INIT_LIST_HEAD(&child->ptrace_entry);
 198         INIT_LIST_HEAD(&child->ptraced);
 199 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 200         atomic_set(&child->ptrace_bp_refcnt, 1);
 201 #endif
 202         child->jobctl = 0;
 203         child->ptrace = 0;
 204         child->parent = child->real_parent;
 205
 206         if (unlikely(ptrace) && current->ptrace) {
 207                 child->ptrace = current->ptrace;
 208                 __ptrace_link(child, current->parent);
 209
 210                 if (child->ptrace & PT_SEIZED)
 211                         task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
 212                 else
 213                         sigaddset(&child->pending.signal, SIGSTOP);
 214
 215                 set_tsk_thread_flag(child, TIF_SIGPENDING);
 216         }
 217 }
 218
 219 /**
 220  * ptrace_release_task - final ptrace-related cleanup of a zombie being reaped
 221  * @task:       task in %EXIT_DEAD state
 222  *
 223  * Called with write_lock(&tasklist_lock) held.
 224  */
 225 static inline void ptrace_release_task(struct task_struct *task)
 226 {
 227         BUG_ON(!list_empty(&task->ptraced));
 228         ptrace_unlink(task);
 229         BUG_ON(!list_empty(&task->ptrace_entry));
 230 }
 231
 232 #ifndef force_successful_syscall_return
 233 /*
 234  * System call handlers that, upon successful completion, need to return a
 235  * negative value should call force_successful_syscall_return() right before
 236  * returning.  On architectures where the syscall convention provides for a
 237  * separate error flag (e.g., alpha, ia64, ppc{,64}, sparc{,64}, possibly
 238  * others), this macro can be used to ensure that the error flag will not get
 239  * set.  On architectures which do not support a separate error flag, the macro
 240  * is a no-op and the spurious error condition needs to be filtered out by some
 241  * other means (e.g., in user-level, by passing an extra argument to the
 242  * syscall handler, or something along those lines).
 243  */
 244 #define force_successful_syscall_return() do { } while (0)
 245 #endif
 246
 247 #ifndef is_syscall_success
 248 /*
 249  * On most systems we can tell if a syscall is a success based on if the retval
 250  * is an error value.  On some systems like ia64 and powerpc they have different
 251  * indicators of success/failure and must define their own.
 252  */
 253 #define is_syscall_success(regs) (!IS_ERR_VALUE((unsigned long)(regs_return_value(regs))))
 254 #endif
 255
 256 /*
 257  * <asm/ptrace.h> should define the following things inside #ifdef __KERNEL__.
 258  *
 259  * These do-nothing inlines are used when the arch does not
 260  * implement single-step.  The kerneldoc comments are here
 261  * to document the interface for all arch definitions.
 262  */
 263
 264 #ifndef arch_has_single_step
 265 /**
 266  * arch_has_single_step - does this CPU support user-mode single-step?
 267  *
 268  * If this is defined, then there must be function declarations or
 269  * inlines for user_enable_single_step() and user_disable_single_step().
 270  * arch_has_single_step() should evaluate to nonzero iff the machine
 271  * supports instruction single-step for user mode.
 272  * It can be a constant or it can test a CPU feature bit.
 273  */
 274 #define arch_has_single_step()          (0)
 275
 276 /**
 277  * user_enable_single_step - single-step in user-mode task
 278  * @task: either current or a task stopped in %TASK_TRACED
 279  *
 280  * This can only be called when arch_has_single_step() has returned nonzero.
 281  * Set @task so that when it returns to user mode, it will trap after the
 282  * next single instruction executes.  If arch_has_block_step() is defined,
 283  * this must clear the effects of user_enable_block_step() too.
 284  */
 285 static inline void user_enable_single_step(struct task_struct *task)
 286 {
 287         BUG();                  /* This can never be called.  */
 288 }
 289
 290 /**
 291  * user_disable_single_step - cancel user-mode single-step
 292  * @task: either current or a task stopped in %TASK_TRACED
 293  *
 294  * Clear @task of the effects of user_enable_single_step() and
 295  * user_enable_block_step().  This can be called whether or not either
 296  * of those was ever called on @task, and even if arch_has_single_step()
 297  * returned zero.
 298  */
 299 static inline void user_disable_single_step(struct task_struct *task)
 300 {
 301 }
 302 #else
 303 extern void user_enable_single_step(struct task_struct *);
 304 extern void user_disable_single_step(struct task_struct *);
 305 #endif  /* arch_has_single_step */
 306
 307 #ifndef arch_has_block_step
 308 /**
 309  * arch_has_block_step - does this CPU support user-mode block-step?
 310  *
 311  * If this is defined, then there must be a function declaration or inline
 312  * for user_enable_block_step(), and arch_has_single_step() must be defined
 313  * too.  arch_has_block_step() should evaluate to nonzero iff the machine
 314  * supports step-until-branch for user mode.  It can be a constant or it
 315  * can test a CPU feature bit.
 316  */
 317 #define arch_has_block_step()           (0)
 318
 319 /**
 320  * user_enable_block_step - step until branch in user-mode task
 321  * @task: either current or a task stopped in %TASK_TRACED
 322  *
 323  * This can only be called when arch_has_block_step() has returned nonzero,
 324  * and will never be called when single-instruction stepping is being used.
 325  * Set @task so that when it returns to user mode, it will trap after the
 326  * next branch or trap taken.
 327  */
 328 static inline void user_enable_block_step(struct task_struct *task)
 329 {
 330         BUG();                  /* This can never be called.  */
 331 }
 332 #else
 333 extern void user_enable_block_step(struct task_struct *);
 334 #endif  /* arch_has_block_step */
 335
 336 #ifdef ARCH_HAS_USER_SINGLE_STEP_INFO
 337 extern void user_single_step_siginfo(struct task_struct *tsk,
 338                                 struct pt_regs *regs, siginfo_t *info);
 339 #else
 340 static inline void user_single_step_siginfo(struct task_struct *tsk,
 341                                 struct pt_regs *regs, siginfo_t *info)
 342 {
 343         memset(info, 0, sizeof(*info));
 344         info->si_signo = SIGTRAP;
 345 }
 346 #endif
 347
 348 #ifndef arch_ptrace_stop_needed
 349 /**
 350  * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
 351  * @code:       current->exit_code value ptrace will stop with
 352  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
 353  *
 354  * This is called with the siglock held, to decide whether or not it's
 355  * necessary to release the siglock and call arch_ptrace_stop() with the
 356  * same @code and @info arguments.  It can be defined to a constant if
 357  * arch_ptrace_stop() is never required, or always is.  On machines where
 358  * this makes sense, it should be defined to a quick test to optimize out
 359  * calling arch_ptrace_stop() when it would be superfluous.  For example,
 360  * if the thread has not been back to user mode since the last stop, the
 361  * thread state might indicate that nothing needs to be done.
 362  *
 363  * This is guaranteed to be invoked once before a task stops for ptrace and
 364  * may include arch-specific operations necessary prior to a ptrace stop.
 365  */
 366 #define arch_ptrace_stop_needed(code, info)     (0)
 367 #endif
 368
 369 #ifndef arch_ptrace_stop
 370 /**
 371  * arch_ptrace_stop - Do machine-specific work before stopping for ptrace
 372  * @code:       current->exit_code value ptrace will stop with
 373  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
 374  *
 375  * This is called with no locks held when arch_ptrace_stop_needed() has
 376  * just returned nonzero.  It is allowed to block, e.g. for user memory
 377  * access.  The arch can have machine-specific work to be done before
 378  * ptrace stops.  On ia64, register backing store gets written back to user
 379  * memory here.  Since this can be costly (requires dropping the siglock),
 380  * we only do it when the arch requires it for this particular stop, as
 381  * indicated by arch_ptrace_stop_needed().
 382  */
 383 #define arch_ptrace_stop(code, info)            do { } while (0)
 384 #endif
 385
 386 #ifndef current_pt_regs
 387 #define current_pt_regs() task_pt_regs(current)
 388 #endif
 389
 390 #ifndef ptrace_signal_deliver
 391 #define ptrace_signal_deliver() ((void)0)
 392 #endif
 393
 394 /*
 395  * unlike current_pt_regs(), this one is equal to task_pt_regs(current)
 396  * on *all* architectures; the only reason to have a per-arch definition
 397  * is optimisation.
 398  */
 399 #ifndef signal_pt_regs
 400 #define signal_pt_regs() task_pt_regs(current)
 401 #endif
 402
 403 #ifndef current_user_stack_pointer
 404 #define current_user_stack_pointer() user_stack_pointer(current_pt_regs())
 405 #endif
 406
 407 extern int task_current_syscall(struct task_struct *target, long *callno,
 408                                 unsigned long args[6], unsigned int maxargs,
 409                                 unsigned long *sp, unsigned long *pc);
 410
 411 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 412 extern int ptrace_get_breakpoints(struct task_struct *tsk);
 413 extern void ptrace_put_breakpoints(struct task_struct *tsk);
 414 #else
 415 static inline void ptrace_put_breakpoints(struct task_struct *tsk) { }
 416 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
 417
 418 #endif