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 #include <linux/seccomp.h>
  13
  14 /* Add sp to seccomp_data, as seccomp is user API, we don't want to modify it */
  15 struct syscall_info {
  16         __u64                   sp;
  17         struct seccomp_data     data;
  18 };
  19
  20 extern int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,
  21                             void *buf, int len, unsigned int gup_flags);
  22
  23 /*
  24  * Ptrace flags
  25  *
  26  * The owner ship rules for task->ptrace which holds the ptrace
  27  * flags is simple.  When a task is running it owns it's task->ptrace
  28  * flags.  When the a task is stopped the ptracer owns task->ptrace.
  29  */
  30
  31 #define PT_SEIZED       0x00010000      /* SEIZE used, enable new behavior */
  32 #define PT_PTRACED      0x00000001
  33 #define PT_DTRACE       0x00000002      /* delayed trace (used on m68k, i386) */
  34
  35 #define PT_OPT_FLAG_SHIFT       3
  36 /* PT_TRACE_* event enable flags */
  37 #define PT_EVENT_FLAG(event)    (1 << (PT_OPT_FLAG_SHIFT + (event)))
  38 #define PT_TRACESYSGOOD         PT_EVENT_FLAG(0)
  39 #define PT_TRACE_FORK           PT_EVENT_FLAG(PTRACE_EVENT_FORK)
  40 #define PT_TRACE_VFORK          PT_EVENT_FLAG(PTRACE_EVENT_VFORK)
  41 #define PT_TRACE_CLONE          PT_EVENT_FLAG(PTRACE_EVENT_CLONE)
  42 #define PT_TRACE_EXEC           PT_EVENT_FLAG(PTRACE_EVENT_EXEC)
  43 #define PT_TRACE_VFORK_DONE     PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE)
  44 #define PT_TRACE_EXIT           PT_EVENT_FLAG(PTRACE_EVENT_EXIT)
  45 #define PT_TRACE_SECCOMP        PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP)
  46
  47 #define PT_EXITKILL             (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
  48 #define PT_SUSPEND_SECCOMP      (PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT)
  49
  50 /* single stepping state bits (used on ARM and PA-RISC) */
  51 #define PT_SINGLESTEP_BIT       31
  52 #define PT_SINGLESTEP           (1<<PT_SINGLESTEP_BIT)
  53 #define PT_BLOCKSTEP_BIT        30
  54 #define PT_BLOCKSTEP            (1<<PT_BLOCKSTEP_BIT)
  55
  56 extern long arch_ptrace(struct task_struct *child, long request,
  57                         unsigned long addr, unsigned long data);
  58 extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);
  59 extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len);
  60 extern void ptrace_disable(struct task_struct *);
  61 extern int ptrace_request(struct task_struct *child, long request,
  62                           unsigned long addr, unsigned long data);
  63 extern void ptrace_notify(int exit_code);
  64 extern void __ptrace_link(struct task_struct *child,
  65                           struct task_struct *new_parent,
  66                           const struct cred *ptracer_cred);
  67 extern void __ptrace_unlink(struct task_struct *child);
  68 extern void exit_ptrace(struct task_struct *tracer, struct list_head *dead);
  69 #define PTRACE_MODE_READ        0x01
  70 #define PTRACE_MODE_ATTACH      0x02
  71 #define PTRACE_MODE_NOAUDIT     0x04
  72 #define PTRACE_MODE_FSCREDS     0x08
  73 #define PTRACE_MODE_REALCREDS   0x10
  74
  75 /* shorthands for READ/ATTACH and FSCREDS/REALCREDS combinations */
  76 #define PTRACE_MODE_READ_FSCREDS (PTRACE_MODE_READ | PTRACE_MODE_FSCREDS)
  77 #define PTRACE_MODE_READ_REALCREDS (PTRACE_MODE_READ | PTRACE_MODE_REALCREDS)
  78 #define PTRACE_MODE_ATTACH_FSCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_FSCREDS)
  79 #define PTRACE_MODE_ATTACH_REALCREDS (PTRACE_MODE_ATTACH | PTRACE_MODE_REALCREDS)
  80
  81 /**
  82  * ptrace_may_access - check whether the caller is permitted to access
  83  * a target task.
  84  * @task: target task
  85  * @mode: selects type of access and caller credentials
  86  *
  87  * Returns true on success, false on denial.
  88  *
  89  * One of the flags PTRACE_MODE_FSCREDS and PTRACE_MODE_REALCREDS must
  90  * be set in @mode to specify whether the access was requested through
  91  * a filesystem syscall (should use effective capabilities and fsuid
  92  * of the caller) or through an explicit syscall such as
  93  * process_vm_writev or ptrace (and should use the real credentials).
  94  */
  95 extern bool ptrace_may_access(struct task_struct *task, unsigned int mode);
  96
  97 static inline int ptrace_reparented(struct task_struct *child)
  98 {
  99         return !same_thread_group(child->real_parent, child->parent);
 100 }
 101
 102 static inline void ptrace_unlink(struct task_struct *child)
 103 {
 104         if (unlikely(child->ptrace))
 105                 __ptrace_unlink(child);
 106 }
 107
 108 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
 109                             unsigned long data);
 110 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
 111                             unsigned long data);
 112
 113 /**
 114  * ptrace_parent - return the task that is tracing the given task
 115  * @task: task to consider
 116  *
 117  * Returns %NULL if no one is tracing @task, or the &struct task_struct
 118  * pointer to its tracer.
 119  *
 120  * Must called under rcu_read_lock().  The pointer returned might be kept
 121  * live only by RCU.  During exec, this may be called with task_lock() held
 122  * on @task, still held from when check_unsafe_exec() was called.
 123  */
 124 static inline struct task_struct *ptrace_parent(struct task_struct *task)
 125 {
 126         if (unlikely(task->ptrace))
 127                 return rcu_dereference(task->parent);
 128         return NULL;
 129 }
 130
 131 /**
 132  * ptrace_event_enabled - test whether a ptrace event is enabled
 133  * @task: ptracee of interest
 134  * @event: %PTRACE_EVENT_* to test
 135  *
 136  * Test whether @event is enabled for ptracee @task.
 137  *
 138  * Returns %true if @event is enabled, %false otherwise.
 139  */
 140 static inline bool ptrace_event_enabled(struct task_struct *task, int event)
 141 {
 142         return task->ptrace & PT_EVENT_FLAG(event);
 143 }
 144
 145 /**
 146  * ptrace_event - possibly stop for a ptrace event notification
 147  * @event:      %PTRACE_EVENT_* value to report
 148  * @message:    value for %PTRACE_GETEVENTMSG to return
 149  *
 150  * Check whether @event is enabled and, if so, report @event and @message
 151  * to the ptrace parent.
 152  *
 153  * Called without locks.
 154  */
 155 static inline void ptrace_event(int event, unsigned long message)
 156 {
 157         if (unlikely(ptrace_event_enabled(current, event))) {
 158                 current->ptrace_message = message;
 159                 ptrace_notify((event << 8) | SIGTRAP);
 160         } else if (event == PTRACE_EVENT_EXEC) {
 161                 /* legacy EXEC report via SIGTRAP */
 162                 if ((current->ptrace & (PT_PTRACED|PT_SEIZED)) == PT_PTRACED)
 163                         send_sig(SIGTRAP, current, 0);
 164         }
 165 }
 166
 167 /**
 168  * ptrace_event_pid - possibly stop for a ptrace event notification
 169  * @event:      %PTRACE_EVENT_* value to report
 170  * @pid:        process identifier for %PTRACE_GETEVENTMSG to return
 171  *
 172  * Check whether @event is enabled and, if so, report @event and @pid
 173  * to the ptrace parent.  @pid is reported as the pid_t seen from the
 174  * the ptrace parent's pid namespace.
 175  *
 176  * Called without locks.
 177  */
 178 static inline void ptrace_event_pid(int event, struct pid *pid)
 179 {
 180         /*
 181          * FIXME: There's a potential race if a ptracer in a different pid
 182          * namespace than parent attaches between computing message below and
 183          * when we acquire tasklist_lock in ptrace_stop().  If this happens,
 184          * the ptracer will get a bogus pid from PTRACE_GETEVENTMSG.
 185          */
 186         unsigned long message = 0;
 187         struct pid_namespace *ns;
 188
 189         rcu_read_lock();
 190         ns = task_active_pid_ns(rcu_dereference(current->parent));
 191         if (ns)
 192                 message = pid_nr_ns(pid, ns);
 193         rcu_read_unlock();
 194
 195         ptrace_event(event, message);
 196 }
 197
 198 /**
 199  * ptrace_init_task - initialize ptrace state for a new child
 200  * @child:              new child task
 201  * @ptrace:             true if child should be ptrace'd by parent's tracer
 202  *
 203  * This is called immediately after adding @child to its parent's children
 204  * list.  @ptrace is false in the normal case, and true to ptrace @child.
 205  *
 206  * Called with current's siglock and write_lock_irq(&tasklist_lock) held.
 207  */
 208 static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
 209 {
 210         INIT_LIST_HEAD(&child->ptrace_entry);
 211         INIT_LIST_HEAD(&child->ptraced);
 212         child->jobctl = 0;
 213         child->ptrace = 0;
 214         child->parent = child->real_parent;
 215
 216         if (unlikely(ptrace) && current->ptrace) {
 217                 child->ptrace = current->ptrace;
 218                 __ptrace_link(child, current->parent, current->ptracer_cred);
 219
 220                 if (child->ptrace & PT_SEIZED)
 221                         task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
 222                 else
 223                         sigaddset(&child->pending.signal, SIGSTOP);
 224         }
 225         else
 226                 child->ptracer_cred = NULL;
 227 }
 228
 229 /**
 230  * ptrace_release_task - final ptrace-related cleanup of a zombie being reaped
 231  * @task:       task in %EXIT_DEAD state
 232  *
 233  * Called with write_lock(&tasklist_lock) held.
 234  */
 235 static inline void ptrace_release_task(struct task_struct *task)
 236 {
 237         BUG_ON(!list_empty(&task->ptraced));
 238         ptrace_unlink(task);
 239         BUG_ON(!list_empty(&task->ptrace_entry));
 240 }
 241
 242 #ifndef force_successful_syscall_return
 243 /*
 244  * System call handlers that, upon successful completion, need to return a
 245  * negative value should call force_successful_syscall_return() right before
 246  * returning.  On architectures where the syscall convention provides for a
 247  * separate error flag (e.g., alpha, ia64, ppc{,64}, sparc{,64}, possibly
 248  * others), this macro can be used to ensure that the error flag will not get
 249  * set.  On architectures which do not support a separate error flag, the macro
 250  * is a no-op and the spurious error condition needs to be filtered out by some
 251  * other means (e.g., in user-level, by passing an extra argument to the
 252  * syscall handler, or something along those lines).
 253  */
 254 #define force_successful_syscall_return() do { } while (0)
 255 #endif
 256
 257 #ifndef is_syscall_success
 258 /*
 259  * On most systems we can tell if a syscall is a success based on if the retval
 260  * is an error value.  On some systems like ia64 and powerpc they have different
 261  * indicators of success/failure and must define their own.
 262  */
 263 #define is_syscall_success(regs) (!IS_ERR_VALUE((unsigned long)(regs_return_value(regs))))
 264 #endif
 265
 266 /*
 267  * <asm/ptrace.h> should define the following things inside #ifdef __KERNEL__.
 268  *
 269  * These do-nothing inlines are used when the arch does not
 270  * implement single-step.  The kerneldoc comments are here
 271  * to document the interface for all arch definitions.
 272  */
 273
 274 #ifndef arch_has_single_step
 275 /**
 276  * arch_has_single_step - does this CPU support user-mode single-step?
 277  *
 278  * If this is defined, then there must be function declarations or
 279  * inlines for user_enable_single_step() and user_disable_single_step().
 280  * arch_has_single_step() should evaluate to nonzero iff the machine
 281  * supports instruction single-step for user mode.
 282  * It can be a constant or it can test a CPU feature bit.
 283  */
 284 #define arch_has_single_step()          (0)
 285
 286 /**
 287  * user_enable_single_step - single-step in user-mode task
 288  * @task: either current or a task stopped in %TASK_TRACED
 289  *
 290  * This can only be called when arch_has_single_step() has returned nonzero.
 291  * Set @task so that when it returns to user mode, it will trap after the
 292  * next single instruction executes.  If arch_has_block_step() is defined,
 293  * this must clear the effects of user_enable_block_step() too.
 294  */
 295 static inline void user_enable_single_step(struct task_struct *task)
 296 {
 297         BUG();                  /* This can never be called.  */
 298 }
 299
 300 /**
 301  * user_disable_single_step - cancel user-mode single-step
 302  * @task: either current or a task stopped in %TASK_TRACED
 303  *
 304  * Clear @task of the effects of user_enable_single_step() and
 305  * user_enable_block_step().  This can be called whether or not either
 306  * of those was ever called on @task, and even if arch_has_single_step()
 307  * returned zero.
 308  */
 309 static inline void user_disable_single_step(struct task_struct *task)
 310 {
 311 }
 312 #else
 313 extern void user_enable_single_step(struct task_struct *);
 314 extern void user_disable_single_step(struct task_struct *);
 315 #endif  /* arch_has_single_step */
 316
 317 #ifndef arch_has_block_step
 318 /**
 319  * arch_has_block_step - does this CPU support user-mode block-step?
 320  *
 321  * If this is defined, then there must be a function declaration or inline
 322  * for user_enable_block_step(), and arch_has_single_step() must be defined
 323  * too.  arch_has_block_step() should evaluate to nonzero iff the machine
 324  * supports step-until-branch for user mode.  It can be a constant or it
 325  * can test a CPU feature bit.
 326  */
 327 #define arch_has_block_step()           (0)
 328
 329 /**
 330  * user_enable_block_step - step until branch in user-mode task
 331  * @task: either current or a task stopped in %TASK_TRACED
 332  *
 333  * This can only be called when arch_has_block_step() has returned nonzero,
 334  * and will never be called when single-instruction stepping is being used.
 335  * Set @task so that when it returns to user mode, it will trap after the
 336  * next branch or trap taken.
 337  */
 338 static inline void user_enable_block_step(struct task_struct *task)
 339 {
 340         BUG();                  /* This can never be called.  */
 341 }
 342 #else
 343 extern void user_enable_block_step(struct task_struct *);
 344 #endif  /* arch_has_block_step */
 345
 346 #ifdef ARCH_HAS_USER_SINGLE_STEP_REPORT
 347 extern void user_single_step_report(struct pt_regs *regs);
 348 #else
 349 static inline void user_single_step_report(struct pt_regs *regs)
 350 {
 351         kernel_siginfo_t info;
 352         clear_siginfo(&info);
 353         info.si_signo = SIGTRAP;
 354         info.si_errno = 0;
 355         info.si_code = SI_USER;
 356         info.si_pid = 0;
 357         info.si_uid = 0;
 358         force_sig_info(&info);
 359 }
 360 #endif
 361
 362 #ifndef arch_ptrace_stop_needed
 363 /**
 364  * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
 365  * @code:       current->exit_code value ptrace will stop with
 366  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
 367  *
 368  * This is called with the siglock held, to decide whether or not it's
 369  * necessary to release the siglock and call arch_ptrace_stop() with the
 370  * same @code and @info arguments.  It can be defined to a constant if
 371  * arch_ptrace_stop() is never required, or always is.  On machines where
 372  * this makes sense, it should be defined to a quick test to optimize out
 373  * calling arch_ptrace_stop() when it would be superfluous.  For example,
 374  * if the thread has not been back to user mode since the last stop, the
 375  * thread state might indicate that nothing needs to be done.
 376  *
 377  * This is guaranteed to be invoked once before a task stops for ptrace and
 378  * may include arch-specific operations necessary prior to a ptrace stop.
 379  */
 380 #define arch_ptrace_stop_needed(code, info)     (0)
 381 #endif
 382
 383 #ifndef arch_ptrace_stop
 384 /**
 385  * arch_ptrace_stop - Do machine-specific work before stopping for ptrace
 386  * @code:       current->exit_code value ptrace will stop with
 387  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
 388  *
 389  * This is called with no locks held when arch_ptrace_stop_needed() has
 390  * just returned nonzero.  It is allowed to block, e.g. for user memory
 391  * access.  The arch can have machine-specific work to be done before
 392  * ptrace stops.  On ia64, register backing store gets written back to user
 393  * memory here.  Since this can be costly (requires dropping the siglock),
 394  * we only do it when the arch requires it for this particular stop, as
 395  * indicated by arch_ptrace_stop_needed().
 396  */
 397 #define arch_ptrace_stop(code, info)            do { } while (0)
 398 #endif
 399
 400 #ifndef current_pt_regs
 401 #define current_pt_regs() task_pt_regs(current)
 402 #endif
 403
 404 /*
 405  * unlike current_pt_regs(), this one is equal to task_pt_regs(current)
 406  * on *all* architectures; the only reason to have a per-arch definition
 407  * is optimisation.
 408  */
 409 #ifndef signal_pt_regs
 410 #define signal_pt_regs() task_pt_regs(current)
 411 #endif
 412
 413 #ifndef current_user_stack_pointer
 414 #define current_user_stack_pointer() user_stack_pointer(current_pt_regs())
 415 #endif
 416
 417 extern int task_current_syscall(struct task_struct *target, struct syscall_info *info);
 418
 419 extern void sigaction_compat_abi(struct k_sigaction *act, struct k_sigaction *oact);
 420 #endif