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/sched/signal.h>         /* For send_sig(), same_thread_group(), etc. */
   7 #include <linux/err.h>                  /* for IS_ERR_VALUE */
   8 #include <linux/bug.h>                  /* For BUG_ON.  */
   9 #include <linux/pid_namespace.h>        /* For task_active_pid_ns.  */
  10 #include <uapi/linux/ptrace.h>
  11
  12 extern int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,
  13                             void *buf, int len, unsigned int gup_flags);
  14
  15 /*
  16  * Ptrace flags
  17  *
  18  * The owner ship rules for task->ptrace which holds the ptrace
  19  * flags is simple.  When a task is running it owns it's task->ptrace
  20  * flags.  When the a task is stopped the ptracer owns task->ptrace.
  21  */
  22
  23 #define PT_SEIZED       0x00010000      /* SEIZE used, enable new behavior */
  24 #define PT_PTRACED      0x00000001
  25 #define PT_DTRACE       0x00000002      /* delayed trace (used on m68k, i386) */
  26
  27 #define PT_OPT_FLAG_SHIFT       3
  28 /* PT_TRACE_* event enable flags */
  29 #define PT_EVENT_FLAG(event)    (1 << (PT_OPT_FLAG_SHIFT + (event)))
  30 #define PT_TRACESYSGOOD         PT_EVENT_FLAG(0)
  31 #define PT_TRACE_FORK           PT_EVENT_FLAG(PTRACE_EVENT_FORK)
  32 #define PT_TRACE_VFORK          PT_EVENT_FLAG(PTRACE_EVENT_VFORK)
  33 #define PT_TRACE_CLONE          PT_EVENT_FLAG(PTRACE_EVENT_CLONE)
  34 #define PT_TRACE_EXEC           PT_EVENT_FLAG(PTRACE_EVENT_EXEC)
  35 #define PT_TRACE_VFORK_DONE     PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE)
  36 #define PT_TRACE_EXIT           PT_EVENT_FLAG(PTRACE_EVENT_EXIT)
  37 #define PT_TRACE_SECCOMP        PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP)
  38
  39 #define PT_EXITKILL             (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
  40 #define PT_SUSPEND_SECCOMP      (PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT)
  41
  42 /* single stepping state bits (used on ARM and PA-RISC) */
  43 #define PT_SINGLESTEP_BIT       31
  44 #define PT_SINGLESTEP           (1<<PT_SINGLESTEP_BIT)
  45 #define PT_BLOCKSTEP_BIT        30
  46 #define PT_BLOCKSTEP            (1<<PT_BLOCKSTEP_BIT)
  47
  48 extern long arch_ptrace(struct task_struct *child, long request,
  49                         unsigned long addr, unsigned long data);
  50 extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);
  51 extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len);
  52 extern void ptrace_disable(struct task_struct *);
  53 extern int ptrace_request(struct task_struct *child, long request,
  54                           unsigned long addr, unsigned long data);
  55 extern void ptrace_notify(int exit_code);
  56 extern void __ptrace_link(struct task_struct *child,
  57                           struct task_struct *new_parent,
  58                           const struct cred *ptracer_cred);
  59 extern void __ptrace_unlink(struct task_struct *child);
  60 extern void exit_ptrace(struct task_struct *tracer, struct list_head *dead);
  61 #define PTRACE_MODE_READ        0x01
  62 #define PTRACE_MODE_ATTACH      0x02
  63 #define PTRACE_MODE_NOAUDIT     0x04
  64 #define PTRACE_MODE_FSCREDS 0x08
  65 #define PTRACE_MODE_REALCREDS 0x10
  66
  67 /* shorthands for READ/ATTACH and FSCREDS/REALCREDS combinations */
  68 #define PTRACE_MODE_READ_FSCREDS (PTRACE_MODE_READ | PTRACE_MODE_FSCREDS)
  69 #define PTRACE_MODE_READ_REALCREDS (PTRACE_MODE_READ | PTRACE_MODE_REALCREDS)
  70 #define PTRACE_MODE_ATTACH_FSCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_FSCREDS)
  71 #define PTRACE_MODE_ATTACH_REALCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_REALCREDS)
  72
  73 /**
  74  * ptrace_may_access - check whether the caller is permitted to access
  75  * a target task.
  76  * @task: target task
  77  * @mode: selects type of access and caller credentials
  78  *
  79  * Returns true on success, false on denial.
  80  *
  81  * One of the flags PTRACE_MODE_FSCREDS and PTRACE_MODE_REALCREDS must
  82  * be set in @mode to specify whether the access was requested through
  83  * a filesystem syscall (should use effective capabilities and fsuid
  84  * of the caller) or through an explicit syscall such as
  85  * process_vm_writev or ptrace (and should use the real credentials).
  86  */
  87 extern bool ptrace_may_access(struct task_struct *task, unsigned int mode);
  88
  89 static inline int ptrace_reparented(struct task_struct *child)
  90 {
  91         return !same_thread_group(child->real_parent, child->parent);
  92 }
  93
  94 static inline void ptrace_unlink(struct task_struct *child)
  95 {
  96         if (unlikely(child->ptrace))
  97                 __ptrace_unlink(child);
  98 }
  99
 100 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
 101                             unsigned long data);
 102 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
 103                             unsigned long data);
 104
 105 /**
 106  * ptrace_parent - return the task that is tracing the given task
 107  * @task: task to consider
 108  *
 109  * Returns %NULL if no one is tracing @task, or the &struct task_struct
 110  * pointer to its tracer.
 111  *
 112  * Must called under rcu_read_lock().  The pointer returned might be kept
 113  * live only by RCU.  During exec, this may be called with task_lock() held
 114  * on @task, still held from when check_unsafe_exec() was called.
 115  */
 116 static inline struct task_struct *ptrace_parent(struct task_struct *task)
 117 {
 118         if (unlikely(task->ptrace))
 119                 return rcu_dereference(task->parent);
 120         return NULL;
 121 }
 122
 123 /**
 124  * ptrace_event_enabled - test whether a ptrace event is enabled
 125  * @task: ptracee of interest
 126  * @event: %PTRACE_EVENT_* to test
 127  *
 128  * Test whether @event is enabled for ptracee @task.
 129  *
 130  * Returns %true if @event is enabled, %false otherwise.
 131  */
 132 static inline bool ptrace_event_enabled(struct task_struct *task, int event)
 133 {
 134         return task->ptrace & PT_EVENT_FLAG(event);
 135 }
 136
 137 /**
 138  * ptrace_event - possibly stop for a ptrace event notification
 139  * @event:      %PTRACE_EVENT_* value to report
 140  * @message:    value for %PTRACE_GETEVENTMSG to return
 141  *
 142  * Check whether @event is enabled and, if so, report @event and @message
 143  * to the ptrace parent.
 144  *
 145  * Called without locks.
 146  */
 147 static inline void ptrace_event(int event, unsigned long message)
 148 {
 149         if (unlikely(ptrace_event_enabled(current, event))) {
 150                 current->ptrace_message = message;
 151                 ptrace_notify((event << 8) | SIGTRAP);
 152         } else if (event == PTRACE_EVENT_EXEC) {
 153                 /* legacy EXEC report via SIGTRAP */
 154                 if ((current->ptrace & (PT_PTRACED|PT_SEIZED)) == PT_PTRACED)
 155                         send_sig(SIGTRAP, current, 0);
 156         }
 157 }
 158
 159 /**
 160  * ptrace_event_pid - possibly stop for a ptrace event notification
 161  * @event:      %PTRACE_EVENT_* value to report
 162  * @pid:        process identifier for %PTRACE_GETEVENTMSG to return
 163  *
 164  * Check whether @event is enabled and, if so, report @event and @pid
 165  * to the ptrace parent.  @pid is reported as the pid_t seen from the
 166  * the ptrace parent's pid namespace.
 167  *
 168  * Called without locks.
 169  */
 170 static inline void ptrace_event_pid(int event, struct pid *pid)
 171 {
 172         /*
 173          * FIXME: There's a potential race if a ptracer in a different pid
 174          * namespace than parent attaches between computing message below and
 175          * when we acquire tasklist_lock in ptrace_stop().  If this happens,
 176          * the ptracer will get a bogus pid from PTRACE_GETEVENTMSG.
 177          */
 178         unsigned long message = 0;
 179         struct pid_namespace *ns;
 180
 181         rcu_read_lock();
 182         ns = task_active_pid_ns(rcu_dereference(current->parent));
 183         if (ns)
 184                 message = pid_nr_ns(pid, ns);
 185         rcu_read_unlock();
 186
 187         ptrace_event(event, message);
 188 }
 189
 190 /**
 191  * ptrace_init_task - initialize ptrace state for a new child
 192  * @child:              new child task
 193  * @ptrace:             true if child should be ptrace'd by parent's tracer
 194  *
 195  * This is called immediately after adding @child to its parent's children
 196  * list.  @ptrace is false in the normal case, and true to ptrace @child.
 197  *
 198  * Called with current's siglock and write_lock_irq(&tasklist_lock) held.
 199  */
 200 static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
 201 {
 202         INIT_LIST_HEAD(&child->ptrace_entry);
 203         INIT_LIST_HEAD(&child->ptraced);
 204         child->jobctl = 0;
 205         child->ptrace = 0;
 206         child->parent = child->real_parent;
 207
 208         if (unlikely(ptrace) && current->ptrace) {
 209                 child->ptrace = current->ptrace;
 210                 __ptrace_link(child, current->parent, current->ptracer_cred);
 211
 212                 if (child->ptrace & PT_SEIZED)
 213                         task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
 214                 else
 215                         sigaddset(&child->pending.signal, SIGSTOP);
 216
 217                 set_tsk_thread_flag(child, TIF_SIGPENDING);
 218         }
 219         else
 220                 child->ptracer_cred = NULL;
 221 }
 222
 223 /**
 224  * ptrace_release_task - final ptrace-related cleanup of a zombie being reaped
 225  * @task:       task in %EXIT_DEAD state
 226  *
 227  * Called with write_lock(&tasklist_lock) held.
 228  */
 229 static inline void ptrace_release_task(struct task_struct *task)
 230 {
 231         BUG_ON(!list_empty(&task->ptraced));
 232         ptrace_unlink(task);
 233         BUG_ON(!list_empty(&task->ptrace_entry));
 234 }
 235
 236 #ifndef force_successful_syscall_return
 237 /*
 238  * System call handlers that, upon successful completion, need to return a
 239  * negative value should call force_successful_syscall_return() right before
 240  * returning.  On architectures where the syscall convention provides for a
 241  * separate error flag (e.g., alpha, ia64, ppc{,64}, sparc{,64}, possibly
 242  * others), this macro can be used to ensure that the error flag will not get
 243  * set.  On architectures which do not support a separate error flag, the macro
 244  * is a no-op and the spurious error condition needs to be filtered out by some
 245  * other means (e.g., in user-level, by passing an extra argument to the
 246  * syscall handler, or something along those lines).
 247  */
 248 #define force_successful_syscall_return() do { } while (0)
 249 #endif
 250
 251 #ifndef is_syscall_success
 252 /*
 253  * On most systems we can tell if a syscall is a success based on if the retval
 254  * is an error value.  On some systems like ia64 and powerpc they have different
 255  * indicators of success/failure and must define their own.
 256  */
 257 #define is_syscall_success(regs) (!IS_ERR_VALUE((unsigned long)(regs_return_value(regs))))
 258 #endif
 259
 260 /*
 261  * <asm/ptrace.h> should define the following things inside #ifdef __KERNEL__.
 262  *
 263  * These do-nothing inlines are used when the arch does not
 264  * implement single-step.  The kerneldoc comments are here
 265  * to document the interface for all arch definitions.
 266  */
 267
 268 #ifndef arch_has_single_step
 269 /**
 270  * arch_has_single_step - does this CPU support user-mode single-step?
 271  *
 272  * If this is defined, then there must be function declarations or
 273  * inlines for user_enable_single_step() and user_disable_single_step().
 274  * arch_has_single_step() should evaluate to nonzero iff the machine
 275  * supports instruction single-step for user mode.
 276  * It can be a constant or it can test a CPU feature bit.
 277  */
 278 #define arch_has_single_step()          (0)
 279
 280 /**
 281  * user_enable_single_step - single-step in user-mode task
 282  * @task: either current or a task stopped in %TASK_TRACED
 283  *
 284  * This can only be called when arch_has_single_step() has returned nonzero.
 285  * Set @task so that when it returns to user mode, it will trap after the
 286  * next single instruction executes.  If arch_has_block_step() is defined,
 287  * this must clear the effects of user_enable_block_step() too.
 288  */
 289 static inline void user_enable_single_step(struct task_struct *task)
 290 {
 291         BUG();                  /* This can never be called.  */
 292 }
 293
 294 /**
 295  * user_disable_single_step - cancel user-mode single-step
 296  * @task: either current or a task stopped in %TASK_TRACED
 297  *
 298  * Clear @task of the effects of user_enable_single_step() and
 299  * user_enable_block_step().  This can be called whether or not either
 300  * of those was ever called on @task, and even if arch_has_single_step()
 301  * returned zero.
 302  */
 303 static inline void user_disable_single_step(struct task_struct *task)
 304 {
 305 }
 306 #else
 307 extern void user_enable_single_step(struct task_struct *);
 308 extern void user_disable_single_step(struct task_struct *);
 309 #endif  /* arch_has_single_step */
 310
 311 #ifndef arch_has_block_step
 312 /**
 313  * arch_has_block_step - does this CPU support user-mode block-step?
 314  *
 315  * If this is defined, then there must be a function declaration or inline
 316  * for user_enable_block_step(), and arch_has_single_step() must be defined
 317  * too.  arch_has_block_step() should evaluate to nonzero iff the machine
 318  * supports step-until-branch for user mode.  It can be a constant or it
 319  * can test a CPU feature bit.
 320  */
 321 #define arch_has_block_step()           (0)
 322
 323 /**
 324  * user_enable_block_step - step until branch in user-mode task
 325  * @task: either current or a task stopped in %TASK_TRACED
 326  *
 327  * This can only be called when arch_has_block_step() has returned nonzero,
 328  * and will never be called when single-instruction stepping is being used.
 329  * Set @task so that when it returns to user mode, it will trap after the
 330  * next branch or trap taken.
 331  */
 332 static inline void user_enable_block_step(struct task_struct *task)
 333 {
 334         BUG();                  /* This can never be called.  */
 335 }
 336 #else
 337 extern void user_enable_block_step(struct task_struct *);
 338 #endif  /* arch_has_block_step */
 339
 340 #ifdef ARCH_HAS_USER_SINGLE_STEP_INFO
 341 extern void user_single_step_siginfo(struct task_struct *tsk,
 342                                 struct pt_regs *regs, siginfo_t *info);
 343 #else
 344 static inline void user_single_step_siginfo(struct task_struct *tsk,
 345                                 struct pt_regs *regs, siginfo_t *info)
 346 {
 347         memset(info, 0, sizeof(*info));
 348         info->si_signo = SIGTRAP;
 349 }
 350 #endif
 351
 352 #ifndef arch_ptrace_stop_needed
 353 /**
 354  * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
 355  * @code:       current->exit_code value ptrace will stop with
 356  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
 357  *
 358  * This is called with the siglock held, to decide whether or not it's
 359  * necessary to release the siglock and call arch_ptrace_stop() with the
 360  * same @code and @info arguments.  It can be defined to a constant if
 361  * arch_ptrace_stop() is never required, or always is.  On machines where
 362  * this makes sense, it should be defined to a quick test to optimize out
 363  * calling arch_ptrace_stop() when it would be superfluous.  For example,
 364  * if the thread has not been back to user mode since the last stop, the
 365  * thread state might indicate that nothing needs to be done.
 366  *
 367  * This is guaranteed to be invoked once before a task stops for ptrace and
 368  * may include arch-specific operations necessary prior to a ptrace stop.
 369  */
 370 #define arch_ptrace_stop_needed(code, info)     (0)
 371 #endif
 372
 373 #ifndef arch_ptrace_stop
 374 /**
 375  * arch_ptrace_stop - Do machine-specific work before stopping for ptrace
 376  * @code:       current->exit_code value ptrace will stop with
 377  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
 378  *
 379  * This is called with no locks held when arch_ptrace_stop_needed() has
 380  * just returned nonzero.  It is allowed to block, e.g. for user memory
 381  * access.  The arch can have machine-specific work to be done before
 382  * ptrace stops.  On ia64, register backing store gets written back to user
 383  * memory here.  Since this can be costly (requires dropping the siglock),
 384  * we only do it when the arch requires it for this particular stop, as
 385  * indicated by arch_ptrace_stop_needed().
 386  */
 387 #define arch_ptrace_stop(code, info)            do { } while (0)
 388 #endif
 389
 390 #ifndef current_pt_regs
 391 #define current_pt_regs() task_pt_regs(current)
 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 #endif