include/linux/ptrace.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_PTRACE_H
   3 #define _LINUX_PTRACE_H
   4
   5 #include <linux/compiler.h>             /* For unlikely.  */
   6 #include <linux/sched.h>                /* For struct task_struct.  */
   7 #include <linux/sched/signal.h>         /* For send_sig(), same_thread_group(), etc. */
   8 #include <linux/err.h>                  /* for IS_ERR_VALUE */
   9 #include <linux/bug.h>                  /* For BUG_ON.  */
  10 #include <linux/pid_namespace.h>        /* For task_active_pid_ns.  */
  11 #include <uapi/linux/ptrace.h>
  12
  13 extern int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,
  14                             void *buf, int len, unsigned int gup_flags);
  15
  16 /*
  17  * Ptrace flags
  18  *
  19  * The owner ship rules for task->ptrace which holds the ptrace
  20  * flags is simple.  When a task is running it owns it's task->ptrace
  21  * flags.  When the a task is stopped the ptracer owns task->ptrace.
  22  */
  23
  24 #define PT_SEIZED       0x00010000      /* SEIZE used, enable new behavior */
  25 #define PT_PTRACED      0x00000001
  26 #define PT_DTRACE       0x00000002      /* delayed trace (used on m68k, i386) */
  27
  28 #define PT_OPT_FLAG_SHIFT       3
  29 /* PT_TRACE_* event enable flags */
  30 #define PT_EVENT_FLAG(event)    (1 << (PT_OPT_FLAG_SHIFT + (event)))
  31 #define PT_TRACESYSGOOD         PT_EVENT_FLAG(0)
  32 #define PT_TRACE_FORK           PT_EVENT_FLAG(PTRACE_EVENT_FORK)
  33 #define PT_TRACE_VFORK          PT_EVENT_FLAG(PTRACE_EVENT_VFORK)
  34 #define PT_TRACE_CLONE          PT_EVENT_FLAG(PTRACE_EVENT_CLONE)
  35 #define PT_TRACE_EXEC           PT_EVENT_FLAG(PTRACE_EVENT_EXEC)
  36 #define PT_TRACE_VFORK_DONE     PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE)
  37 #define PT_TRACE_EXIT           PT_EVENT_FLAG(PTRACE_EVENT_EXIT)
  38 #define PT_TRACE_SECCOMP        PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP)
  39
  40 #define PT_EXITKILL             (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
  41 #define PT_SUSPEND_SECCOMP      (PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT)
  42
  43 /* single stepping state bits (used on ARM and PA-RISC) */
  44 #define PT_SINGLESTEP_BIT       31
  45 #define PT_SINGLESTEP           (1<<PT_SINGLESTEP_BIT)
  46 #define PT_BLOCKSTEP_BIT        30
  47 #define PT_BLOCKSTEP            (1<<PT_BLOCKSTEP_BIT)
  48
  49 extern long arch_ptrace(struct task_struct *child, long request,
  50                         unsigned long addr, unsigned long data);
  51 extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);
  52 extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len);
  53 extern void ptrace_disable(struct task_struct *);
  54 extern int ptrace_request(struct task_struct *child, long request,
  55                           unsigned long addr, unsigned long data);
  56 extern void ptrace_notify(int exit_code);
  57 extern void __ptrace_link(struct task_struct *child,
  58                           struct task_struct *new_parent,
  59                           const struct cred *ptracer_cred);
  60 extern void __ptrace_unlink(struct task_struct *child);
  61 extern void exit_ptrace(struct task_struct *tracer, struct list_head *dead);
  62 #define PTRACE_MODE_READ        0x01
  63 #define PTRACE_MODE_ATTACH      0x02
  64 #define PTRACE_MODE_NOAUDIT     0x04
  65 #define PTRACE_MODE_FSCREDS     0x08
  66 #define PTRACE_MODE_REALCREDS   0x10
  67
  68 /* shorthands for READ/ATTACH and FSCREDS/REALCREDS combinations */
  69 #define PTRACE_MODE_READ_FSCREDS (PTRACE_MODE_READ | PTRACE_MODE_FSCREDS)
  70 #define PTRACE_MODE_READ_REALCREDS (PTRACE_MODE_READ | PTRACE_MODE_REALCREDS)
  71 #define PTRACE_MODE_ATTACH_FSCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_FSCREDS)
  72 #define PTRACE_MODE_ATTACH_REALCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_REALCREDS)
  73
  74 /**
  75  * ptrace_may_access - check whether the caller is permitted to access
  76  * a target task.
  77  * @task: target task
  78  * @mode: selects type of access and caller credentials
  79  *
  80  * Returns true on success, false on denial.
  81  *
  82  * One of the flags PTRACE_MODE_FSCREDS and PTRACE_MODE_REALCREDS must
  83  * be set in @mode to specify whether the access was requested through
  84  * a filesystem syscall (should use effective capabilities and fsuid
  85  * of the caller) or through an explicit syscall such as
  86  * process_vm_writev or ptrace (and should use the real credentials).
  87  */
  88 extern bool ptrace_may_access(struct task_struct *task, unsigned int mode);
  89
  90 static inline int ptrace_reparented(struct task_struct *child)
  91 {
  92         return !same_thread_group(child->real_parent, child->parent);
  93 }
  94
  95 static inline void ptrace_unlink(struct task_struct *child)
  96 {
  97         if (unlikely(child->ptrace))
  98                 __ptrace_unlink(child);
  99 }
 100
 101 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
 102                             unsigned long data);
 103 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
 104                             unsigned long data);
 105
 106 /**
 107  * ptrace_parent - return the task that is tracing the given task
 108  * @task: task to consider
 109  *
 110  * Returns %NULL if no one is tracing @task, or the &struct task_struct
 111  * pointer to its tracer.
 112  *
 113  * Must called under rcu_read_lock().  The pointer returned might be kept
 114  * live only by RCU.  During exec, this may be called with task_lock() held
 115  * on @task, still held from when check_unsafe_exec() was called.
 116  */
 117 static inline struct task_struct *ptrace_parent(struct task_struct *task)
 118 {
 119         if (unlikely(task->ptrace))
 120                 return rcu_dereference(task->parent);
 121         return NULL;
 122 }
 123
 124 /**
 125  * ptrace_event_enabled - test whether a ptrace event is enabled
 126  * @task: ptracee of interest
 127  * @event: %PTRACE_EVENT_* to test
 128  *
 129  * Test whether @event is enabled for ptracee @task.
 130  *
 131  * Returns %true if @event is enabled, %false otherwise.
 132  */
 133 static inline bool ptrace_event_enabled(struct task_struct *task, int event)
 134 {
 135         return task->ptrace & PT_EVENT_FLAG(event);
 136 }
 137
 138 /**
 139  * ptrace_event - possibly stop for a ptrace event notification
 140  * @event:      %PTRACE_EVENT_* value to report
 141  * @message:    value for %PTRACE_GETEVENTMSG to return
 142  *
 143  * Check whether @event is enabled and, if so, report @event and @message
 144  * to the ptrace parent.
 145  *
 146  * Called without locks.
 147  */
 148 static inline void ptrace_event(int event, unsigned long message)
 149 {
 150         if (unlikely(ptrace_event_enabled(current, event))) {
 151                 current->ptrace_message = message;
 152                 ptrace_notify((event << 8) | SIGTRAP);
 153         } else if (event == PTRACE_EVENT_EXEC) {
 154                 /* legacy EXEC report via SIGTRAP */
 155                 if ((current->ptrace & (PT_PTRACED|PT_SEIZED)) == PT_PTRACED)
 156                         send_sig(SIGTRAP, current, 0);
 157         }
 158 }
 159
 160 /**
 161  * ptrace_event_pid - possibly stop for a ptrace event notification
 162  * @event:      %PTRACE_EVENT_* value to report
 163  * @pid:        process identifier for %PTRACE_GETEVENTMSG to return
 164  *
 165  * Check whether @event is enabled and, if so, report @event and @pid
 166  * to the ptrace parent.  @pid is reported as the pid_t seen from the
 167  * the ptrace parent's pid namespace.
 168  *
 169  * Called without locks.
 170  */
 171 static inline void ptrace_event_pid(int event, struct pid *pid)
 172 {
 173         /*
 174          * FIXME: There's a potential race if a ptracer in a different pid
 175          * namespace than parent attaches between computing message below and
 176          * when we acquire tasklist_lock in ptrace_stop().  If this happens,
 177          * the ptracer will get a bogus pid from PTRACE_GETEVENTMSG.
 178          */
 179         unsigned long message = 0;
 180         struct pid_namespace *ns;
 181
 182         rcu_read_lock();
 183         ns = task_active_pid_ns(rcu_dereference(current->parent));
 184         if (ns)
 185                 message = pid_nr_ns(pid, ns);
 186         rcu_read_unlock();
 187
 188         ptrace_event(event, message);
 189 }
 190
 191 /**
 192  * ptrace_init_task - initialize ptrace state for a new child
 193  * @child:              new child task
 194  * @ptrace:             true if child should be ptrace'd by parent's tracer
 195  *
 196  * This is called immediately after adding @child to its parent's children
 197  * list.  @ptrace is false in the normal case, and true to ptrace @child.
 198  *
 199  * Called with current's siglock and write_lock_irq(&tasklist_lock) held.
 200  */
 201 static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
 202 {
 203         INIT_LIST_HEAD(&child->ptrace_entry);
 204         INIT_LIST_HEAD(&child->ptraced);
 205         child->jobctl = 0;
 206         child->ptrace = 0;
 207         child->parent = child->real_parent;
 208
 209         if (unlikely(ptrace) && current->ptrace) {
 210                 child->ptrace = current->ptrace;
 211                 __ptrace_link(child, current->parent, current->ptracer_cred);
 212
 213                 if (child->ptrace & PT_SEIZED)
 214                         task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
 215                 else
 216                         sigaddset(&child->pending.signal, SIGSTOP);
 217
 218                 set_tsk_thread_flag(child, TIF_SIGPENDING);
 219         }
 220         else
 221                 child->ptracer_cred = NULL;
 222 }
 223
 224 /**
 225  * ptrace_release_task - final ptrace-related cleanup of a zombie being reaped
 226  * @task:       task in %EXIT_DEAD state
 227  *
 228  * Called with write_lock(&tasklist_lock) held.
 229  */
 230 static inline void ptrace_release_task(struct task_struct *task)
 231 {
 232         BUG_ON(!list_empty(&task->ptraced));
 233         ptrace_unlink(task);
 234         BUG_ON(!list_empty(&task->ptrace_entry));
 235 }
 236
 237 #ifndef force_successful_syscall_return
 238 /*
 239  * System call handlers that, upon successful completion, need to return a
 240  * negative value should call force_successful_syscall_return() right before
 241  * returning.  On architectures where the syscall convention provides for a
 242  * separate error flag (e.g., alpha, ia64, ppc{,64}, sparc{,64}, possibly
 243  * others), this macro can be used to ensure that the error flag will not get
 244  * set.  On architectures which do not support a separate error flag, the macro
 245  * is a no-op and the spurious error condition needs to be filtered out by some
 246  * other means (e.g., in user-level, by passing an extra argument to the
 247  * syscall handler, or something along those lines).
 248  */
 249 #define force_successful_syscall_return() do { } while (0)
 250 #endif
 251
 252 #ifndef is_syscall_success
 253 /*
 254  * On most systems we can tell if a syscall is a success based on if the retval
 255  * is an error value.  On some systems like ia64 and powerpc they have different
 256  * indicators of success/failure and must define their own.
 257  */
 258 #define is_syscall_success(regs) (!IS_ERR_VALUE((unsigned long)(regs_return_value(regs))))
 259 #endif
 260
 261 /*
 262  * <asm/ptrace.h> should define the following things inside #ifdef __KERNEL__.
 263  *
 264  * These do-nothing inlines are used when the arch does not
 265  * implement single-step.  The kerneldoc comments are here
 266  * to document the interface for all arch definitions.
 267  */
 268
 269 #ifndef arch_has_single_step
 270 /**
 271  * arch_has_single_step - does this CPU support user-mode single-step?
 272  *
 273  * If this is defined, then there must be function declarations or
 274  * inlines for user_enable_single_step() and user_disable_single_step().
 275  * arch_has_single_step() should evaluate to nonzero iff the machine
 276  * supports instruction single-step for user mode.
 277  * It can be a constant or it can test a CPU feature bit.
 278  */
 279 #define arch_has_single_step()          (0)
 280
 281 /**
 282  * user_enable_single_step - single-step in user-mode task
 283  * @task: either current or a task stopped in %TASK_TRACED
 284  *
 285  * This can only be called when arch_has_single_step() has returned nonzero.
 286  * Set @task so that when it returns to user mode, it will trap after the
 287  * next single instruction executes.  If arch_has_block_step() is defined,
 288  * this must clear the effects of user_enable_block_step() too.
 289  */
 290 static inline void user_enable_single_step(struct task_struct *task)
 291 {
 292         BUG();                  /* This can never be called.  */
 293 }
 294
 295 /**
 296  * user_disable_single_step - cancel user-mode single-step
 297  * @task: either current or a task stopped in %TASK_TRACED
 298  *
 299  * Clear @task of the effects of user_enable_single_step() and
 300  * user_enable_block_step().  This can be called whether or not either
 301  * of those was ever called on @task, and even if arch_has_single_step()
 302  * returned zero.
 303  */
 304 static inline void user_disable_single_step(struct task_struct *task)
 305 {
 306 }
 307 #else
 308 extern void user_enable_single_step(struct task_struct *);
 309 extern void user_disable_single_step(struct task_struct *);
 310 #endif  /* arch_has_single_step */
 311
 312 #ifndef arch_has_block_step
 313 /**
 314  * arch_has_block_step - does this CPU support user-mode block-step?
 315  *
 316  * If this is defined, then there must be a function declaration or inline
 317  * for user_enable_block_step(), and arch_has_single_step() must be defined
 318  * too.  arch_has_block_step() should evaluate to nonzero iff the machine
 319  * supports step-until-branch for user mode.  It can be a constant or it
 320  * can test a CPU feature bit.
 321  */
 322 #define arch_has_block_step()           (0)
 323
 324 /**
 325  * user_enable_block_step - step until branch in user-mode task
 326  * @task: either current or a task stopped in %TASK_TRACED
 327  *
 328  * This can only be called when arch_has_block_step() has returned nonzero,
 329  * and will never be called when single-instruction stepping is being used.
 330  * Set @task so that when it returns to user mode, it will trap after the
 331  * next branch or trap taken.
 332  */
 333 static inline void user_enable_block_step(struct task_struct *task)
 334 {
 335         BUG();                  /* This can never be called.  */
 336 }
 337 #else
 338 extern void user_enable_block_step(struct task_struct *);
 339 #endif  /* arch_has_block_step */
 340
 341 #ifdef ARCH_HAS_USER_SINGLE_STEP_INFO
 342 extern void user_single_step_siginfo(struct task_struct *tsk,
 343                                 struct pt_regs *regs, siginfo_t *info);
 344 #else
 345 static inline void user_single_step_siginfo(struct task_struct *tsk,
 346                                 struct pt_regs *regs, siginfo_t *info)
 347 {
 348         memset(info, 0, sizeof(*info));
 349         info->si_signo = SIGTRAP;
 350 }
 351 #endif
 352
 353 #ifndef arch_ptrace_stop_needed
 354 /**
 355  * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
 356  * @code:       current->exit_code value ptrace will stop with
 357  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
 358  *
 359  * This is called with the siglock held, to decide whether or not it's
 360  * necessary to release the siglock and call arch_ptrace_stop() with the
 361  * same @code and @info arguments.  It can be defined to a constant if
 362  * arch_ptrace_stop() is never required, or always is.  On machines where
 363  * this makes sense, it should be defined to a quick test to optimize out
 364  * calling arch_ptrace_stop() when it would be superfluous.  For example,
 365  * if the thread has not been back to user mode since the last stop, the
 366  * thread state might indicate that nothing needs to be done.
 367  *
 368  * This is guaranteed to be invoked once before a task stops for ptrace and
 369  * may include arch-specific operations necessary prior to a ptrace stop.
 370  */
 371 #define arch_ptrace_stop_needed(code, info)     (0)
 372 #endif
 373
 374 #ifndef arch_ptrace_stop
 375 /**
 376  * arch_ptrace_stop - Do machine-specific work before stopping for ptrace
 377  * @code:       current->exit_code value ptrace will stop with
 378  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
 379  *
 380  * This is called with no locks held when arch_ptrace_stop_needed() has
 381  * just returned nonzero.  It is allowed to block, e.g. for user memory
 382  * access.  The arch can have machine-specific work to be done before
 383  * ptrace stops.  On ia64, register backing store gets written back to user
 384  * memory here.  Since this can be costly (requires dropping the siglock),
 385  * we only do it when the arch requires it for this particular stop, as
 386  * indicated by arch_ptrace_stop_needed().
 387  */
 388 #define arch_ptrace_stop(code, info)            do { } while (0)
 389 #endif
 390
 391 #ifndef current_pt_regs
 392 #define current_pt_regs() task_pt_regs(current)
 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