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 extern void __ptrace_unlink(struct task_struct *child);
  59 extern void exit_ptrace(struct task_struct *tracer, struct list_head *dead);
  60 #define PTRACE_MODE_READ        0x01
  61 #define PTRACE_MODE_ATTACH      0x02
  62 #define PTRACE_MODE_NOAUDIT     0x04
  63 #define PTRACE_MODE_FSCREDS 0x08
  64 #define PTRACE_MODE_REALCREDS 0x10
  65
  66 /* shorthands for READ/ATTACH and FSCREDS/REALCREDS combinations */
  67 #define PTRACE_MODE_READ_FSCREDS (PTRACE_MODE_READ | PTRACE_MODE_FSCREDS)
  68 #define PTRACE_MODE_READ_REALCREDS (PTRACE_MODE_READ | PTRACE_MODE_REALCREDS)
  69 #define PTRACE_MODE_ATTACH_FSCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_FSCREDS)
  70 #define PTRACE_MODE_ATTACH_REALCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_REALCREDS)
  71
  72 /**
  73  * ptrace_may_access - check whether the caller is permitted to access
  74  * a target task.
  75  * @task: target task
  76  * @mode: selects type of access and caller credentials
  77  *
  78  * Returns true on success, false on denial.
  79  *
  80  * One of the flags PTRACE_MODE_FSCREDS and PTRACE_MODE_REALCREDS must
  81  * be set in @mode to specify whether the access was requested through
  82  * a filesystem syscall (should use effective capabilities and fsuid
  83  * of the caller) or through an explicit syscall such as
  84  * process_vm_writev or ptrace (and should use the real credentials).
  85  */
  86 extern bool ptrace_may_access(struct task_struct *task, unsigned int mode);
  87
  88 static inline int ptrace_reparented(struct task_struct *child)
  89 {
  90         return !same_thread_group(child->real_parent, child->parent);
  91 }
  92
  93 static inline void ptrace_unlink(struct task_struct *child)
  94 {
  95         if (unlikely(child->ptrace))
  96                 __ptrace_unlink(child);
  97 }
  98
  99 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
 100                             unsigned long data);
 101 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
 102                             unsigned long data);
 103
 104 /**
 105  * ptrace_parent - return the task that is tracing the given task
 106  * @task: task to consider
 107  *
 108  * Returns %NULL if no one is tracing @task, or the &struct task_struct
 109  * pointer to its tracer.
 110  *
 111  * Must called under rcu_read_lock().  The pointer returned might be kept
 112  * live only by RCU.  During exec, this may be called with task_lock() held
 113  * on @task, still held from when check_unsafe_exec() was called.
 114  */
 115 static inline struct task_struct *ptrace_parent(struct task_struct *task)
 116 {
 117         if (unlikely(task->ptrace))
 118                 return rcu_dereference(task->parent);
 119         return NULL;
 120 }
 121
 122 /**
 123  * ptrace_event_enabled - test whether a ptrace event is enabled
 124  * @task: ptracee of interest
 125  * @event: %PTRACE_EVENT_* to test
 126  *
 127  * Test whether @event is enabled for ptracee @task.
 128  *
 129  * Returns %true if @event is enabled, %false otherwise.
 130  */
 131 static inline bool ptrace_event_enabled(struct task_struct *task, int event)
 132 {
 133         return task->ptrace & PT_EVENT_FLAG(event);
 134 }
 135
 136 /**
 137  * ptrace_event - possibly stop for a ptrace event notification
 138  * @event:      %PTRACE_EVENT_* value to report
 139  * @message:    value for %PTRACE_GETEVENTMSG to return
 140  *
 141  * Check whether @event is enabled and, if so, report @event and @message
 142  * to the ptrace parent.
 143  *
 144  * Called without locks.
 145  */
 146 static inline void ptrace_event(int event, unsigned long message)
 147 {
 148         if (unlikely(ptrace_event_enabled(current, event))) {
 149                 current->ptrace_message = message;
 150                 ptrace_notify((event << 8) | SIGTRAP);
 151         } else if (event == PTRACE_EVENT_EXEC) {
 152                 /* legacy EXEC report via SIGTRAP */
 153                 if ((current->ptrace & (PT_PTRACED|PT_SEIZED)) == PT_PTRACED)
 154                         send_sig(SIGTRAP, current, 0);
 155         }
 156 }
 157
 158 /**
 159  * ptrace_event_pid - possibly stop for a ptrace event notification
 160  * @event:      %PTRACE_EVENT_* value to report
 161  * @pid:        process identifier for %PTRACE_GETEVENTMSG to return
 162  *
 163  * Check whether @event is enabled and, if so, report @event and @pid
 164  * to the ptrace parent.  @pid is reported as the pid_t seen from the
 165  * the ptrace parent's pid namespace.
 166  *
 167  * Called without locks.
 168  */
 169 static inline void ptrace_event_pid(int event, struct pid *pid)
 170 {
 171         /*
 172          * FIXME: There's a potential race if a ptracer in a different pid
 173          * namespace than parent attaches between computing message below and
 174          * when we acquire tasklist_lock in ptrace_stop().  If this happens,
 175          * the ptracer will get a bogus pid from PTRACE_GETEVENTMSG.
 176          */
 177         unsigned long message = 0;
 178         struct pid_namespace *ns;
 179
 180         rcu_read_lock();
 181         ns = task_active_pid_ns(rcu_dereference(current->parent));
 182         if (ns)
 183                 message = pid_nr_ns(pid, ns);
 184         rcu_read_unlock();
 185
 186         ptrace_event(event, message);
 187 }
 188
 189 /**
 190  * ptrace_init_task - initialize ptrace state for a new child
 191  * @child:              new child task
 192  * @ptrace:             true if child should be ptrace'd by parent's tracer
 193  *
 194  * This is called immediately after adding @child to its parent's children
 195  * list.  @ptrace is false in the normal case, and true to ptrace @child.
 196  *
 197  * Called with current's siglock and write_lock_irq(&tasklist_lock) held.
 198  */
 199 static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
 200 {
 201         INIT_LIST_HEAD(&child->ptrace_entry);
 202         INIT_LIST_HEAD(&child->ptraced);
 203         child->jobctl = 0;
 204         child->ptrace = 0;
 205         child->parent = child->real_parent;
 206
 207         if (unlikely(ptrace) && current->ptrace) {
 208                 child->ptrace = current->ptrace;
 209                 __ptrace_link(child, current->parent);
 210
 211                 if (child->ptrace & PT_SEIZED)
 212                         task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
 213                 else
 214                         sigaddset(&child->pending.signal, SIGSTOP);
 215
 216                 set_tsk_thread_flag(child, TIF_SIGPENDING);
 217         }
 218 }
 219
 220 /**
 221  * ptrace_release_task - final ptrace-related cleanup of a zombie being reaped
 222  * @task:       task in %EXIT_DEAD state
 223  *
 224  * Called with write_lock(&tasklist_lock) held.
 225  */
 226 static inline void ptrace_release_task(struct task_struct *task)
 227 {
 228         BUG_ON(!list_empty(&task->ptraced));
 229         ptrace_unlink(task);
 230         BUG_ON(!list_empty(&task->ptrace_entry));
 231 }
 232
 233 #ifndef force_successful_syscall_return
 234 /*
 235  * System call handlers that, upon successful completion, need to return a
 236  * negative value should call force_successful_syscall_return() right before
 237  * returning.  On architectures where the syscall convention provides for a
 238  * separate error flag (e.g., alpha, ia64, ppc{,64}, sparc{,64}, possibly
 239  * others), this macro can be used to ensure that the error flag will not get
 240  * set.  On architectures which do not support a separate error flag, the macro
 241  * is a no-op and the spurious error condition needs to be filtered out by some
 242  * other means (e.g., in user-level, by passing an extra argument to the
 243  * syscall handler, or something along those lines).
 244  */
 245 #define force_successful_syscall_return() do { } while (0)
 246 #endif
 247
 248 #ifndef is_syscall_success
 249 /*
 250  * On most systems we can tell if a syscall is a success based on if the retval
 251  * is an error value.  On some systems like ia64 and powerpc they have different
 252  * indicators of success/failure and must define their own.
 253  */
 254 #define is_syscall_success(regs) (!IS_ERR_VALUE((unsigned long)(regs_return_value(regs))))
 255 #endif
 256
 257 /*
 258  * <asm/ptrace.h> should define the following things inside #ifdef __KERNEL__.
 259  *
 260  * These do-nothing inlines are used when the arch does not
 261  * implement single-step.  The kerneldoc comments are here
 262  * to document the interface for all arch definitions.
 263  */
 264
 265 #ifndef arch_has_single_step
 266 /**
 267  * arch_has_single_step - does this CPU support user-mode single-step?
 268  *
 269  * If this is defined, then there must be function declarations or
 270  * inlines for user_enable_single_step() and user_disable_single_step().
 271  * arch_has_single_step() should evaluate to nonzero iff the machine
 272  * supports instruction single-step for user mode.
 273  * It can be a constant or it can test a CPU feature bit.
 274  */
 275 #define arch_has_single_step()          (0)
 276
 277 /**
 278  * user_enable_single_step - single-step in user-mode task
 279  * @task: either current or a task stopped in %TASK_TRACED
 280  *
 281  * This can only be called when arch_has_single_step() has returned nonzero.
 282  * Set @task so that when it returns to user mode, it will trap after the
 283  * next single instruction executes.  If arch_has_block_step() is defined,
 284  * this must clear the effects of user_enable_block_step() too.
 285  */
 286 static inline void user_enable_single_step(struct task_struct *task)
 287 {
 288         BUG();                  /* This can never be called.  */
 289 }
 290
 291 /**
 292  * user_disable_single_step - cancel user-mode single-step
 293  * @task: either current or a task stopped in %TASK_TRACED
 294  *
 295  * Clear @task of the effects of user_enable_single_step() and
 296  * user_enable_block_step().  This can be called whether or not either
 297  * of those was ever called on @task, and even if arch_has_single_step()
 298  * returned zero.
 299  */
 300 static inline void user_disable_single_step(struct task_struct *task)
 301 {
 302 }
 303 #else
 304 extern void user_enable_single_step(struct task_struct *);
 305 extern void user_disable_single_step(struct task_struct *);
 306 #endif  /* arch_has_single_step */
 307
 308 #ifndef arch_has_block_step
 309 /**
 310  * arch_has_block_step - does this CPU support user-mode block-step?
 311  *
 312  * If this is defined, then there must be a function declaration or inline
 313  * for user_enable_block_step(), and arch_has_single_step() must be defined
 314  * too.  arch_has_block_step() should evaluate to nonzero iff the machine
 315  * supports step-until-branch for user mode.  It can be a constant or it
 316  * can test a CPU feature bit.
 317  */
 318 #define arch_has_block_step()           (0)
 319
 320 /**
 321  * user_enable_block_step - step until branch in user-mode task
 322  * @task: either current or a task stopped in %TASK_TRACED
 323  *
 324  * This can only be called when arch_has_block_step() has returned nonzero,
 325  * and will never be called when single-instruction stepping is being used.
 326  * Set @task so that when it returns to user mode, it will trap after the
 327  * next branch or trap taken.
 328  */
 329 static inline void user_enable_block_step(struct task_struct *task)
 330 {
 331         BUG();                  /* This can never be called.  */
 332 }
 333 #else
 334 extern void user_enable_block_step(struct task_struct *);
 335 #endif  /* arch_has_block_step */
 336
 337 #ifdef ARCH_HAS_USER_SINGLE_STEP_INFO
 338 extern void user_single_step_siginfo(struct task_struct *tsk,
 339                                 struct pt_regs *regs, siginfo_t *info);
 340 #else
 341 static inline void user_single_step_siginfo(struct task_struct *tsk,
 342                                 struct pt_regs *regs, siginfo_t *info)
 343 {
 344         memset(info, 0, sizeof(*info));
 345         info->si_signo = SIGTRAP;
 346 }
 347 #endif
 348
 349 #ifndef arch_ptrace_stop_needed
 350 /**
 351  * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
 352  * @code:       current->exit_code value ptrace will stop with
 353  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
 354  *
 355  * This is called with the siglock held, to decide whether or not it's
 356  * necessary to release the siglock and call arch_ptrace_stop() with the
 357  * same @code and @info arguments.  It can be defined to a constant if
 358  * arch_ptrace_stop() is never required, or always is.  On machines where
 359  * this makes sense, it should be defined to a quick test to optimize out
 360  * calling arch_ptrace_stop() when it would be superfluous.  For example,
 361  * if the thread has not been back to user mode since the last stop, the
 362  * thread state might indicate that nothing needs to be done.
 363  *
 364  * This is guaranteed to be invoked once before a task stops for ptrace and
 365  * may include arch-specific operations necessary prior to a ptrace stop.
 366  */
 367 #define arch_ptrace_stop_needed(code, info)     (0)
 368 #endif
 369
 370 #ifndef arch_ptrace_stop
 371 /**
 372  * arch_ptrace_stop - Do machine-specific work before stopping for ptrace
 373  * @code:       current->exit_code value ptrace will stop with
 374  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
 375  *
 376  * This is called with no locks held when arch_ptrace_stop_needed() has
 377  * just returned nonzero.  It is allowed to block, e.g. for user memory
 378  * access.  The arch can have machine-specific work to be done before
 379  * ptrace stops.  On ia64, register backing store gets written back to user
 380  * memory here.  Since this can be costly (requires dropping the siglock),
 381  * we only do it when the arch requires it for this particular stop, as
 382  * indicated by arch_ptrace_stop_needed().
 383  */
 384 #define arch_ptrace_stop(code, info)            do { } while (0)
 385 #endif
 386
 387 #ifndef current_pt_regs
 388 #define current_pt_regs() task_pt_regs(current)
 389 #endif
 390
 391 #ifndef ptrace_signal_deliver
 392 #define ptrace_signal_deliver() ((void)0)
 393 #endif
 394
 395 /*
 396  * unlike current_pt_regs(), this one is equal to task_pt_regs(current)
 397  * on *all* architectures; the only reason to have a per-arch definition
 398  * is optimisation.
 399  */
 400 #ifndef signal_pt_regs
 401 #define signal_pt_regs() task_pt_regs(current)
 402 #endif
 403
 404 #ifndef current_user_stack_pointer
 405 #define current_user_stack_pointer() user_stack_pointer(current_pt_regs())
 406 #endif
 407
 408 extern int task_current_syscall(struct task_struct *target, long *callno,
 409                                 unsigned long args[6], unsigned int maxargs,
 410                                 unsigned long *sp, unsigned long *pc);
 411
 412 #endif