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 <uapi/linux/ptrace.h>
   9
  10 /*
  11  * Ptrace flags
  12  *
  13  * The owner ship rules for task->ptrace which holds the ptrace
  14  * flags is simple.  When a task is running it owns it's task->ptrace
  15  * flags.  When the a task is stopped the ptracer owns task->ptrace.
  16  */
  17
  18 #define PT_SEIZED       0x00010000      /* SEIZE used, enable new behavior */
  19 #define PT_PTRACED      0x00000001
  20 #define PT_DTRACE       0x00000002      /* delayed trace (used on m68k, i386) */
  21 #define PT_PTRACE_CAP   0x00000004      /* ptracer can follow suid-exec */
  22
  23 #define PT_OPT_FLAG_SHIFT       3
  24 /* PT_TRACE_* event enable flags */
  25 #define PT_EVENT_FLAG(event)    (1 << (PT_OPT_FLAG_SHIFT + (event)))
  26 #define PT_TRACESYSGOOD         PT_EVENT_FLAG(0)
  27 #define PT_TRACE_FORK           PT_EVENT_FLAG(PTRACE_EVENT_FORK)
  28 #define PT_TRACE_VFORK          PT_EVENT_FLAG(PTRACE_EVENT_VFORK)
  29 #define PT_TRACE_CLONE          PT_EVENT_FLAG(PTRACE_EVENT_CLONE)
  30 #define PT_TRACE_EXEC           PT_EVENT_FLAG(PTRACE_EVENT_EXEC)
  31 #define PT_TRACE_VFORK_DONE     PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE)
  32 #define PT_TRACE_EXIT           PT_EVENT_FLAG(PTRACE_EVENT_EXIT)
  33 #define PT_TRACE_SECCOMP        PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP)
  34
  35 /* single stepping state bits (used on ARM and PA-RISC) */
  36 #define PT_SINGLESTEP_BIT       31
  37 #define PT_SINGLESTEP           (1<<PT_SINGLESTEP_BIT)
  38 #define PT_BLOCKSTEP_BIT        30
  39 #define PT_BLOCKSTEP            (1<<PT_BLOCKSTEP_BIT)
  40
  41 extern long arch_ptrace(struct task_struct *child, long request,
  42                         unsigned long addr, unsigned long data);
  43 extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);
  44 extern int ptrace_writedata(struct task_struct *tsk, char __user *src, unsigned long dst, int len);
  45 extern void ptrace_disable(struct task_struct *);
  46 extern int ptrace_check_attach(struct task_struct *task, bool ignore_state);
  47 extern int ptrace_request(struct task_struct *child, long request,
  48                           unsigned long addr, unsigned long data);
  49 extern void ptrace_notify(int exit_code);
  50 extern void __ptrace_link(struct task_struct *child,
  51                           struct task_struct *new_parent);
  52 extern void __ptrace_unlink(struct task_struct *child);
  53 extern void exit_ptrace(struct task_struct *tracer);
  54 #define PTRACE_MODE_READ        0x01
  55 #define PTRACE_MODE_ATTACH      0x02
  56 #define PTRACE_MODE_NOAUDIT     0x04
  57 /* Returns true on success, false on denial. */
  58 extern bool ptrace_may_access(struct task_struct *task, unsigned int mode);
  59
  60 static inline int ptrace_reparented(struct task_struct *child)
  61 {
  62         return !same_thread_group(child->real_parent, child->parent);
  63 }
  64
  65 static inline void ptrace_unlink(struct task_struct *child)
  66 {
  67         if (unlikely(child->ptrace))
  68                 __ptrace_unlink(child);
  69 }
  70
  71 int generic_ptrace_peekdata(struct task_struct *tsk, unsigned long addr,
  72                             unsigned long data);
  73 int generic_ptrace_pokedata(struct task_struct *tsk, unsigned long addr,
  74                             unsigned long data);
  75
  76 /**
  77  * ptrace_parent - return the task that is tracing the given task
  78  * @task: task to consider
  79  *
  80  * Returns %NULL if no one is tracing @task, or the &struct task_struct
  81  * pointer to its tracer.
  82  *
  83  * Must called under rcu_read_lock().  The pointer returned might be kept
  84  * live only by RCU.  During exec, this may be called with task_lock() held
  85  * on @task, still held from when check_unsafe_exec() was called.
  86  */
  87 static inline struct task_struct *ptrace_parent(struct task_struct *task)
  88 {
  89         if (unlikely(task->ptrace))
  90                 return rcu_dereference(task->parent);
  91         return NULL;
  92 }
  93
  94 /**
  95  * ptrace_event_enabled - test whether a ptrace event is enabled
  96  * @task: ptracee of interest
  97  * @event: %PTRACE_EVENT_* to test
  98  *
  99  * Test whether @event is enabled for ptracee @task.
 100  *
 101  * Returns %true if @event is enabled, %false otherwise.
 102  */
 103 static inline bool ptrace_event_enabled(struct task_struct *task, int event)
 104 {
 105         return task->ptrace & PT_EVENT_FLAG(event);
 106 }
 107
 108 /**
 109  * ptrace_event - possibly stop for a ptrace event notification
 110  * @event:      %PTRACE_EVENT_* value to report
 111  * @message:    value for %PTRACE_GETEVENTMSG to return
 112  *
 113  * Check whether @event is enabled and, if so, report @event and @message
 114  * to the ptrace parent.
 115  *
 116  * Called without locks.
 117  */
 118 static inline void ptrace_event(int event, unsigned long message)
 119 {
 120         if (unlikely(ptrace_event_enabled(current, event))) {
 121                 current->ptrace_message = message;
 122                 ptrace_notify((event << 8) | SIGTRAP);
 123         } else if (event == PTRACE_EVENT_EXEC) {
 124                 /* legacy EXEC report via SIGTRAP */
 125                 if ((current->ptrace & (PT_PTRACED|PT_SEIZED)) == PT_PTRACED)
 126                         send_sig(SIGTRAP, current, 0);
 127         }
 128 }
 129
 130 /**
 131  * ptrace_init_task - initialize ptrace state for a new child
 132  * @child:              new child task
 133  * @ptrace:             true if child should be ptrace'd by parent's tracer
 134  *
 135  * This is called immediately after adding @child to its parent's children
 136  * list.  @ptrace is false in the normal case, and true to ptrace @child.
 137  *
 138  * Called with current's siglock and write_lock_irq(&tasklist_lock) held.
 139  */
 140 static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
 141 {
 142         INIT_LIST_HEAD(&child->ptrace_entry);
 143         INIT_LIST_HEAD(&child->ptraced);
 144 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 145         atomic_set(&child->ptrace_bp_refcnt, 1);
 146 #endif
 147         child->jobctl = 0;
 148         child->ptrace = 0;
 149         child->parent = child->real_parent;
 150
 151         if (unlikely(ptrace) && current->ptrace) {
 152                 child->ptrace = current->ptrace;
 153                 __ptrace_link(child, current->parent);
 154
 155                 if (child->ptrace & PT_SEIZED)
 156                         task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
 157                 else
 158                         sigaddset(&child->pending.signal, SIGSTOP);
 159
 160                 set_tsk_thread_flag(child, TIF_SIGPENDING);
 161         }
 162 }
 163
 164 /**
 165  * ptrace_release_task - final ptrace-related cleanup of a zombie being reaped
 166  * @task:       task in %EXIT_DEAD state
 167  *
 168  * Called with write_lock(&tasklist_lock) held.
 169  */
 170 static inline void ptrace_release_task(struct task_struct *task)
 171 {
 172         BUG_ON(!list_empty(&task->ptraced));
 173         ptrace_unlink(task);
 174         BUG_ON(!list_empty(&task->ptrace_entry));
 175 }
 176
 177 #ifndef force_successful_syscall_return
 178 /*
 179  * System call handlers that, upon successful completion, need to return a
 180  * negative value should call force_successful_syscall_return() right before
 181  * returning.  On architectures where the syscall convention provides for a
 182  * separate error flag (e.g., alpha, ia64, ppc{,64}, sparc{,64}, possibly
 183  * others), this macro can be used to ensure that the error flag will not get
 184  * set.  On architectures which do not support a separate error flag, the macro
 185  * is a no-op and the spurious error condition needs to be filtered out by some
 186  * other means (e.g., in user-level, by passing an extra argument to the
 187  * syscall handler, or something along those lines).
 188  */
 189 #define force_successful_syscall_return() do { } while (0)
 190 #endif
 191
 192 #ifndef is_syscall_success
 193 /*
 194  * On most systems we can tell if a syscall is a success based on if the retval
 195  * is an error value.  On some systems like ia64 and powerpc they have different
 196  * indicators of success/failure and must define their own.
 197  */
 198 #define is_syscall_success(regs) (!IS_ERR_VALUE((unsigned long)(regs_return_value(regs))))
 199 #endif
 200
 201 /*
 202  * <asm/ptrace.h> should define the following things inside #ifdef __KERNEL__.
 203  *
 204  * These do-nothing inlines are used when the arch does not
 205  * implement single-step.  The kerneldoc comments are here
 206  * to document the interface for all arch definitions.
 207  */
 208
 209 #ifndef arch_has_single_step
 210 /**
 211  * arch_has_single_step - does this CPU support user-mode single-step?
 212  *
 213  * If this is defined, then there must be function declarations or
 214  * inlines for user_enable_single_step() and user_disable_single_step().
 215  * arch_has_single_step() should evaluate to nonzero iff the machine
 216  * supports instruction single-step for user mode.
 217  * It can be a constant or it can test a CPU feature bit.
 218  */
 219 #define arch_has_single_step()          (0)
 220
 221 /**
 222  * user_enable_single_step - single-step in user-mode task
 223  * @task: either current or a task stopped in %TASK_TRACED
 224  *
 225  * This can only be called when arch_has_single_step() has returned nonzero.
 226  * Set @task so that when it returns to user mode, it will trap after the
 227  * next single instruction executes.  If arch_has_block_step() is defined,
 228  * this must clear the effects of user_enable_block_step() too.
 229  */
 230 static inline void user_enable_single_step(struct task_struct *task)
 231 {
 232         BUG();                  /* This can never be called.  */
 233 }
 234
 235 /**
 236  * user_disable_single_step - cancel user-mode single-step
 237  * @task: either current or a task stopped in %TASK_TRACED
 238  *
 239  * Clear @task of the effects of user_enable_single_step() and
 240  * user_enable_block_step().  This can be called whether or not either
 241  * of those was ever called on @task, and even if arch_has_single_step()
 242  * returned zero.
 243  */
 244 static inline void user_disable_single_step(struct task_struct *task)
 245 {
 246 }
 247 #else
 248 extern void user_enable_single_step(struct task_struct *);
 249 extern void user_disable_single_step(struct task_struct *);
 250 #endif  /* arch_has_single_step */
 251
 252 #ifndef arch_has_block_step
 253 /**
 254  * arch_has_block_step - does this CPU support user-mode block-step?
 255  *
 256  * If this is defined, then there must be a function declaration or inline
 257  * for user_enable_block_step(), and arch_has_single_step() must be defined
 258  * too.  arch_has_block_step() should evaluate to nonzero iff the machine
 259  * supports step-until-branch for user mode.  It can be a constant or it
 260  * can test a CPU feature bit.
 261  */
 262 #define arch_has_block_step()           (0)
 263
 264 /**
 265  * user_enable_block_step - step until branch in user-mode task
 266  * @task: either current or a task stopped in %TASK_TRACED
 267  *
 268  * This can only be called when arch_has_block_step() has returned nonzero,
 269  * and will never be called when single-instruction stepping is being used.
 270  * Set @task so that when it returns to user mode, it will trap after the
 271  * next branch or trap taken.
 272  */
 273 static inline void user_enable_block_step(struct task_struct *task)
 274 {
 275         BUG();                  /* This can never be called.  */
 276 }
 277 #else
 278 extern void user_enable_block_step(struct task_struct *);
 279 #endif  /* arch_has_block_step */
 280
 281 #ifdef ARCH_HAS_USER_SINGLE_STEP_INFO
 282 extern void user_single_step_siginfo(struct task_struct *tsk,
 283                                 struct pt_regs *regs, siginfo_t *info);
 284 #else
 285 static inline void user_single_step_siginfo(struct task_struct *tsk,
 286                                 struct pt_regs *regs, siginfo_t *info)
 287 {
 288         memset(info, 0, sizeof(*info));
 289         info->si_signo = SIGTRAP;
 290 }
 291 #endif
 292
 293 #ifndef arch_ptrace_stop_needed
 294 /**
 295  * arch_ptrace_stop_needed - Decide whether arch_ptrace_stop() should be called
 296  * @code:       current->exit_code value ptrace will stop with
 297  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
 298  *
 299  * This is called with the siglock held, to decide whether or not it's
 300  * necessary to release the siglock and call arch_ptrace_stop() with the
 301  * same @code and @info arguments.  It can be defined to a constant if
 302  * arch_ptrace_stop() is never required, or always is.  On machines where
 303  * this makes sense, it should be defined to a quick test to optimize out
 304  * calling arch_ptrace_stop() when it would be superfluous.  For example,
 305  * if the thread has not been back to user mode since the last stop, the
 306  * thread state might indicate that nothing needs to be done.
 307  */
 308 #define arch_ptrace_stop_needed(code, info)     (0)
 309 #endif
 310
 311 #ifndef arch_ptrace_stop
 312 /**
 313  * arch_ptrace_stop - Do machine-specific work before stopping for ptrace
 314  * @code:       current->exit_code value ptrace will stop with
 315  * @info:       siginfo_t pointer (or %NULL) for signal ptrace will stop with
 316  *
 317  * This is called with no locks held when arch_ptrace_stop_needed() has
 318  * just returned nonzero.  It is allowed to block, e.g. for user memory
 319  * access.  The arch can have machine-specific work to be done before
 320  * ptrace stops.  On ia64, register backing store gets written back to user
 321  * memory here.  Since this can be costly (requires dropping the siglock),
 322  * we only do it when the arch requires it for this particular stop, as
 323  * indicated by arch_ptrace_stop_needed().
 324  */
 325 #define arch_ptrace_stop(code, info)            do { } while (0)
 326 #endif
 327
 328 #ifndef current_pt_regs
 329 #define current_pt_regs() task_pt_regs(current)
 330 #endif
 331
 332 extern int task_current_syscall(struct task_struct *target, long *callno,
 333                                 unsigned long args[6], unsigned int maxargs,
 334                                 unsigned long *sp, unsigned long *pc);
 335
 336 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 337 extern int ptrace_get_breakpoints(struct task_struct *tsk);
 338 extern void ptrace_put_breakpoints(struct task_struct *tsk);
 339 #else
 340 static inline void ptrace_put_breakpoints(struct task_struct *tsk) { }
 341 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
 342
 343 #endif