| /* |
| * Tracing hooks |
| * |
| * Copyright (C) 2008 Red Hat, Inc. All rights reserved. |
| * |
| * This copyrighted material is made available to anyone wishing to use, |
| * modify, copy, or redistribute it subject to the terms and conditions |
| * of the GNU General Public License v.2. |
| * |
| * This file defines hook entry points called by core code where |
| * user tracing/debugging support might need to do something. These |
| * entry points are called tracehook_*(). Each hook declared below |
| * has a detailed kerneldoc comment giving the context (locking et |
| * al) from which it is called, and the meaning of its return value. |
| * |
| * Each function here typically has only one call site, so it is ok |
| * to have some nontrivial tracehook_*() inlines. In all cases, the |
| * fast path when no tracing is enabled should be very short. |
| * |
| * The purpose of this file and the tracehook_* layer is to consolidate |
| * the interface that the kernel core and arch code uses to enable any |
| * user debugging or tracing facility (such as ptrace). The interfaces |
| * here are carefully documented so that maintainers of core and arch |
| * code do not need to think about the implementation details of the |
| * tracing facilities. Likewise, maintainers of the tracing code do not |
| * need to understand all the calling core or arch code in detail, just |
| * documented circumstances of each call, such as locking conditions. |
| * |
| * If the calling core code changes so that locking is different, then |
| * it is ok to change the interface documented here. The maintainer of |
| * core code changing should notify the maintainers of the tracing code |
| * that they need to work out the change. |
| * |
| * Some tracehook_*() inlines take arguments that the current tracing |
| * implementations might not necessarily use. These function signatures |
| * are chosen to pass in all the information that is on hand in the |
| * caller and might conceivably be relevant to a tracer, so that the |
| * core code won't have to be updated when tracing adds more features. |
| * If a call site changes so that some of those parameters are no longer |
| * already on hand without extra work, then the tracehook_* interface |
| * can change so there is no make-work burden on the core code. The |
| * maintainer of core code changing should notify the maintainers of the |
| * tracing code that they need to work out the change. |
| */ |
| |
| #ifndef _LINUX_TRACEHOOK_H |
| #define _LINUX_TRACEHOOK_H 1 |
| |
| #include <linux/sched.h> |
| #include <linux/ptrace.h> |
| #include <linux/security.h> |
| struct linux_binprm; |
| |
| /** |
| * tracehook_expect_breakpoints - guess if task memory might be touched |
| * @task: current task, making a new mapping |
| * |
| * Return nonzero if @task is expected to want breakpoint insertion in |
| * its memory at some point. A zero return is no guarantee it won't |
| * be done, but this is a hint that it's known to be likely. |
| * |
| * May be called with @task->mm->mmap_sem held for writing. |
| */ |
| static inline int tracehook_expect_breakpoints(struct task_struct *task) |
| { |
| return (task_ptrace(task) & PT_PTRACED) != 0; |
| } |
| |
| /* |
| * ptrace report for syscall entry and exit looks identical. |
| */ |
| static inline void ptrace_report_syscall(struct pt_regs *regs) |
| { |
| int ptrace = task_ptrace(current); |
| |
| if (!(ptrace & PT_PTRACED)) |
| return; |
| |
| ptrace_notify(SIGTRAP | ((ptrace & PT_TRACESYSGOOD) ? 0x80 : 0)); |
| |
| /* |
| * this isn't the same as continuing with a signal, but it will do |
| * for normal use. strace only continues with a signal if the |
| * stopping signal is not SIGTRAP. -brl |
| */ |
| if (current->exit_code) { |
| send_sig(current->exit_code, current, 1); |
| current->exit_code = 0; |
| } |
| } |
| |
| /** |
| * tracehook_report_syscall_entry - task is about to attempt a system call |
| * @regs: user register state of current task |
| * |
| * This will be called if %TIF_SYSCALL_TRACE has been set, when the |
| * current task has just entered the kernel for a system call. |
| * Full user register state is available here. Changing the values |
| * in @regs can affect the system call number and arguments to be tried. |
| * It is safe to block here, preventing the system call from beginning. |
| * |
| * Returns zero normally, or nonzero if the calling arch code should abort |
| * the system call. That must prevent normal entry so no system call is |
| * made. If @task ever returns to user mode after this, its register state |
| * is unspecified, but should be something harmless like an %ENOSYS error |
| * return. It should preserve enough information so that syscall_rollback() |
| * can work (see asm-generic/syscall.h). |
| * |
| * Called without locks, just after entering kernel mode. |
| */ |
| static inline __must_check int tracehook_report_syscall_entry( |
| struct pt_regs *regs) |
| { |
| ptrace_report_syscall(regs); |
| return 0; |
| } |
| |
| /** |
| * tracehook_report_syscall_exit - task has just finished a system call |
| * @regs: user register state of current task |
| * @step: nonzero if simulating single-step or block-step |
| * |
| * This will be called if %TIF_SYSCALL_TRACE has been set, when the |
| * current task has just finished an attempted system call. Full |
| * user register state is available here. It is safe to block here, |
| * preventing signals from being processed. |
| * |
| * If @step is nonzero, this report is also in lieu of the normal |
| * trap that would follow the system call instruction because |
| * user_enable_block_step() or user_enable_single_step() was used. |
| * In this case, %TIF_SYSCALL_TRACE might not be set. |
| * |
| * Called without locks, just before checking for pending signals. |
| */ |
| static inline void tracehook_report_syscall_exit(struct pt_regs *regs, int step) |
| { |
| ptrace_report_syscall(regs); |
| } |
| |
| /** |
| * tracehook_unsafe_exec - check for exec declared unsafe due to tracing |
| * @task: current task doing exec |
| * |
| * Return %LSM_UNSAFE_* bits applied to an exec because of tracing. |
| * |
| * Called with task_lock() held on @task. |
| */ |
| static inline int tracehook_unsafe_exec(struct task_struct *task) |
| { |
| int unsafe = 0; |
| int ptrace = task_ptrace(task); |
| if (ptrace & PT_PTRACED) { |
| if (ptrace & PT_PTRACE_CAP) |
| unsafe |= LSM_UNSAFE_PTRACE_CAP; |
| else |
| unsafe |= LSM_UNSAFE_PTRACE; |
| } |
| return unsafe; |
| } |
| |
| /** |
| * tracehook_tracer_task - return the task that is tracing the given task |
| * @tsk: task to consider |
| * |
| * Returns NULL if noone is tracing @task, or the &struct task_struct |
| * pointer to its tracer. |
| * |
| * Must called under rcu_read_lock(). The pointer returned might be kept |
| * live only by RCU. During exec, this may be called with task_lock() |
| * held on @task, still held from when tracehook_unsafe_exec() was called. |
| */ |
| static inline struct task_struct *tracehook_tracer_task(struct task_struct *tsk) |
| { |
| if (task_ptrace(tsk) & PT_PTRACED) |
| return rcu_dereference(tsk->parent); |
| return NULL; |
| } |
| |
| /** |
| * tracehook_report_exec - a successful exec was completed |
| * @fmt: &struct linux_binfmt that performed the exec |
| * @bprm: &struct linux_binprm containing exec details |
| * @regs: user-mode register state |
| * |
| * An exec just completed, we are shortly going to return to user mode. |
| * The freshly initialized register state can be seen and changed in @regs. |
| * The name, file and other pointers in @bprm are still on hand to be |
| * inspected, but will be freed as soon as this returns. |
| * |
| * Called with no locks, but with some kernel resources held live |
| * and a reference on @fmt->module. |
| */ |
| static inline void tracehook_report_exec(struct linux_binfmt *fmt, |
| struct linux_binprm *bprm, |
| struct pt_regs *regs) |
| { |
| if (!ptrace_event(PT_TRACE_EXEC, PTRACE_EVENT_EXEC, 0) && |
| unlikely(task_ptrace(current) & PT_PTRACED)) |
| send_sig(SIGTRAP, current, 0); |
| } |
| |
| /** |
| * tracehook_report_exit - task has begun to exit |
| * @exit_code: pointer to value destined for @current->exit_code |
| * |
| * @exit_code points to the value passed to do_exit(), which tracing |
| * might change here. This is almost the first thing in do_exit(), |
| * before freeing any resources or setting the %PF_EXITING flag. |
| * |
| * Called with no locks held. |
| */ |
| static inline void tracehook_report_exit(long *exit_code) |
| { |
| ptrace_event(PT_TRACE_EXIT, PTRACE_EVENT_EXIT, *exit_code); |
| } |
| |
| /** |
| * tracehook_prepare_clone - prepare for new child to be cloned |
| * @clone_flags: %CLONE_* flags from clone/fork/vfork system call |
| * |
| * This is called before a new user task is to be cloned. |
| * Its return value will be passed to tracehook_finish_clone(). |
| * |
| * Called with no locks held. |
| */ |
| static inline int tracehook_prepare_clone(unsigned clone_flags) |
| { |
| if (clone_flags & CLONE_UNTRACED) |
| return 0; |
| |
| if (clone_flags & CLONE_VFORK) { |
| if (current->ptrace & PT_TRACE_VFORK) |
| return PTRACE_EVENT_VFORK; |
| } else if ((clone_flags & CSIGNAL) != SIGCHLD) { |
| if (current->ptrace & PT_TRACE_CLONE) |
| return PTRACE_EVENT_CLONE; |
| } else if (current->ptrace & PT_TRACE_FORK) |
| return PTRACE_EVENT_FORK; |
| |
| return 0; |
| } |
| |
| /** |
| * tracehook_finish_clone - new child created and being attached |
| * @child: new child task |
| * @clone_flags: %CLONE_* flags from clone/fork/vfork system call |
| * @trace: return value from tracehook_prepare_clone() |
| * |
| * This is called immediately after adding @child to its parent's children list. |
| * The @trace value is that returned by tracehook_prepare_clone(). |
| * |
| * Called with current's siglock and write_lock_irq(&tasklist_lock) held. |
| */ |
| static inline void tracehook_finish_clone(struct task_struct *child, |
| unsigned long clone_flags, int trace) |
| { |
| ptrace_init_task(child, (clone_flags & CLONE_PTRACE) || trace); |
| } |
| |
| /** |
| * tracehook_report_clone - in parent, new child is about to start running |
| * @trace: return value from tracehook_prepare_clone() |
| * @regs: parent's user register state |
| * @clone_flags: flags from parent's system call |
| * @pid: new child's PID in the parent's namespace |
| * @child: new child task |
| * |
| * Called after a child is set up, but before it has been started |
| * running. @trace is the value returned by tracehook_prepare_clone(). |
| * This is not a good place to block, because the child has not started |
| * yet. Suspend the child here if desired, and then block in |
| * tracehook_report_clone_complete(). This must prevent the child from |
| * self-reaping if tracehook_report_clone_complete() uses the @child |
| * pointer; otherwise it might have died and been released by the time |
| * tracehook_report_report_clone_complete() is called. |
| * |
| * Called with no locks held, but the child cannot run until this returns. |
| */ |
| static inline void tracehook_report_clone(int trace, struct pt_regs *regs, |
| unsigned long clone_flags, |
| pid_t pid, struct task_struct *child) |
| { |
| if (unlikely(trace)) { |
| /* |
| * The child starts up with an immediate SIGSTOP. |
| */ |
| sigaddset(&child->pending.signal, SIGSTOP); |
| set_tsk_thread_flag(child, TIF_SIGPENDING); |
| } |
| } |
| |
| /** |
| * tracehook_report_clone_complete - new child is running |
| * @trace: return value from tracehook_prepare_clone() |
| * @regs: parent's user register state |
| * @clone_flags: flags from parent's system call |
| * @pid: new child's PID in the parent's namespace |
| * @child: child task, already running |
| * |
| * This is called just after the child has started running. This is |
| * just before the clone/fork syscall returns, or blocks for vfork |
| * child completion if @clone_flags has the %CLONE_VFORK bit set. |
| * The @child pointer may be invalid if a self-reaping child died and |
| * tracehook_report_clone() took no action to prevent it from self-reaping. |
| * |
| * Called with no locks held. |
| */ |
| static inline void tracehook_report_clone_complete(int trace, |
| struct pt_regs *regs, |
| unsigned long clone_flags, |
| pid_t pid, |
| struct task_struct *child) |
| { |
| if (unlikely(trace)) |
| ptrace_event(0, trace, pid); |
| } |
| |
| /** |
| * tracehook_report_vfork_done - vfork parent's child has exited or exec'd |
| * @child: child task, already running |
| * @pid: new child's PID in the parent's namespace |
| * |
| * Called after a %CLONE_VFORK parent has waited for the child to complete. |
| * The clone/vfork system call will return immediately after this. |
| * The @child pointer may be invalid if a self-reaping child died and |
| * tracehook_report_clone() took no action to prevent it from self-reaping. |
| * |
| * Called with no locks held. |
| */ |
| static inline void tracehook_report_vfork_done(struct task_struct *child, |
| pid_t pid) |
| { |
| ptrace_event(PT_TRACE_VFORK_DONE, PTRACE_EVENT_VFORK_DONE, pid); |
| } |
| |
| /** |
| * tracehook_prepare_release_task - task is being reaped, clean up tracing |
| * @task: task in %EXIT_DEAD state |
| * |
| * This is called in release_task() just before @task gets finally reaped |
| * and freed. This would be the ideal place to remove and clean up any |
| * tracing-related state for @task. |
| * |
| * Called with no locks held. |
| */ |
| static inline void tracehook_prepare_release_task(struct task_struct *task) |
| { |
| } |
| |
| /** |
| * tracehook_finish_release_task - final tracing clean-up |
| * @task: task in %EXIT_DEAD state |
| * |
| * This is called in release_task() when @task is being in the middle of |
| * being reaped. After this, there must be no tracing entanglements. |
| * |
| * Called with write_lock_irq(&tasklist_lock) held. |
| */ |
| static inline void tracehook_finish_release_task(struct task_struct *task) |
| { |
| ptrace_release_task(task); |
| } |
| |
| /** |
| * tracehook_signal_handler - signal handler setup is complete |
| * @sig: number of signal being delivered |
| * @info: siginfo_t of signal being delivered |
| * @ka: sigaction setting that chose the handler |
| * @regs: user register state |
| * @stepping: nonzero if debugger single-step or block-step in use |
| * |
| * Called by the arch code after a signal handler has been set up. |
| * Register and stack state reflects the user handler about to run. |
| * Signal mask changes have already been made. |
| * |
| * Called without locks, shortly before returning to user mode |
| * (or handling more signals). |
| */ |
| static inline void tracehook_signal_handler(int sig, siginfo_t *info, |
| const struct k_sigaction *ka, |
| struct pt_regs *regs, int stepping) |
| { |
| if (stepping) |
| ptrace_notify(SIGTRAP); |
| } |
| |
| /** |
| * tracehook_consider_ignored_signal - suppress short-circuit of ignored signal |
| * @task: task receiving the signal |
| * @sig: signal number being sent |
| * @handler: %SIG_IGN or %SIG_DFL |
| * |
| * Return zero iff tracing doesn't care to examine this ignored signal, |
| * so it can short-circuit normal delivery and never even get queued. |
| * Either @handler is %SIG_DFL and @sig's default is ignore, or it's %SIG_IGN. |
| * |
| * Called with @task->sighand->siglock held. |
| */ |
| static inline int tracehook_consider_ignored_signal(struct task_struct *task, |
| int sig, |
| void __user *handler) |
| { |
| return (task_ptrace(task) & PT_PTRACED) != 0; |
| } |
| |
| /** |
| * tracehook_consider_fatal_signal - suppress special handling of fatal signal |
| * @task: task receiving the signal |
| * @sig: signal number being sent |
| * @handler: %SIG_DFL or %SIG_IGN |
| * |
| * Return nonzero to prevent special handling of this termination signal. |
| * Normally @handler is %SIG_DFL. It can be %SIG_IGN if @sig is ignored, |
| * in which case force_sig() is about to reset it to %SIG_DFL. |
| * When this returns zero, this signal might cause a quick termination |
| * that does not give the debugger a chance to intercept the signal. |
| * |
| * Called with or without @task->sighand->siglock held. |
| */ |
| static inline int tracehook_consider_fatal_signal(struct task_struct *task, |
| int sig, |
| void __user *handler) |
| { |
| return (task_ptrace(task) & PT_PTRACED) != 0; |
| } |
| |
| /** |
| * tracehook_force_sigpending - let tracing force signal_pending(current) on |
| * |
| * Called when recomputing our signal_pending() flag. Return nonzero |
| * to force the signal_pending() flag on, so that tracehook_get_signal() |
| * will be called before the next return to user mode. |
| * |
| * Called with @current->sighand->siglock held. |
| */ |
| static inline int tracehook_force_sigpending(void) |
| { |
| return 0; |
| } |
| |
| /** |
| * tracehook_get_signal - deliver synthetic signal to traced task |
| * @task: @current |
| * @regs: task_pt_regs(@current) |
| * @info: details of synthetic signal |
| * @return_ka: sigaction for synthetic signal |
| * |
| * Return zero to check for a real pending signal normally. |
| * Return -1 after releasing the siglock to repeat the check. |
| * Return a signal number to induce an artifical signal delivery, |
| * setting *@info and *@return_ka to specify its details and behavior. |
| * |
| * The @return_ka->sa_handler value controls the disposition of the |
| * signal, no matter the signal number. For %SIG_DFL, the return value |
| * is a representative signal to indicate the behavior (e.g. %SIGTERM |
| * for death, %SIGQUIT for core dump, %SIGSTOP for job control stop, |
| * %SIGTSTP for stop unless in an orphaned pgrp), but the signal number |
| * reported will be @info->si_signo instead. |
| * |
| * Called with @task->sighand->siglock held, before dequeuing pending signals. |
| */ |
| static inline int tracehook_get_signal(struct task_struct *task, |
| struct pt_regs *regs, |
| siginfo_t *info, |
| struct k_sigaction *return_ka) |
| { |
| return 0; |
| } |
| |
| /** |
| * tracehook_notify_jctl - report about job control stop/continue |
| * @notify: nonzero if this is the last thread in the group to stop |
| * @why: %CLD_STOPPED or %CLD_CONTINUED |
| * |
| * This is called when we might call do_notify_parent_cldstop(). |
| * It's called when about to stop for job control; we are already in |
| * %TASK_STOPPED state, about to call schedule(). It's also called when |
| * a delayed %CLD_STOPPED or %CLD_CONTINUED report is ready to be made. |
| * |
| * Return nonzero to generate a %SIGCHLD with @why, which is |
| * normal if @notify is nonzero. |
| * |
| * Called with no locks held. |
| */ |
| static inline int tracehook_notify_jctl(int notify, int why) |
| { |
| return notify || (current->ptrace & PT_PTRACED); |
| } |
| |
| /** |
| * tracehook_notify_death - task is dead, ready to notify parent |
| * @task: @current task now exiting |
| * @death_cookie: value to pass to tracehook_report_death() |
| * @group_dead: nonzero if this was the last thread in the group to die |
| * |
| * Return the signal number to send our parent with do_notify_parent(), or |
| * zero to send no signal and leave a zombie, or -1 to self-reap right now. |
| * |
| * Called with write_lock_irq(&tasklist_lock) held. |
| */ |
| static inline int tracehook_notify_death(struct task_struct *task, |
| void **death_cookie, int group_dead) |
| { |
| if (task->exit_signal == -1) |
| return task->ptrace ? SIGCHLD : -1; |
| |
| /* |
| * If something other than our normal parent is ptracing us, then |
| * send it a SIGCHLD instead of honoring exit_signal. exit_signal |
| * only has special meaning to our real parent. |
| */ |
| if (thread_group_empty(task) && !ptrace_reparented(task)) |
| return task->exit_signal; |
| |
| return task->ptrace ? SIGCHLD : 0; |
| } |
| |
| /** |
| * tracehook_report_death - task is dead and ready to be reaped |
| * @task: @current task now exiting |
| * @signal: signal number sent to parent, or 0 or -1 |
| * @death_cookie: value passed back from tracehook_notify_death() |
| * @group_dead: nonzero if this was the last thread in the group to die |
| * |
| * Thread has just become a zombie or is about to self-reap. If positive, |
| * @signal is the signal number just sent to the parent (usually %SIGCHLD). |
| * If @signal is -1, this thread will self-reap. If @signal is 0, this is |
| * a delayed_group_leader() zombie. The @death_cookie was passed back by |
| * tracehook_notify_death(). |
| * |
| * If normal reaping is not inhibited, @task->exit_state might be changing |
| * in parallel. |
| * |
| * Called without locks. |
| */ |
| static inline void tracehook_report_death(struct task_struct *task, |
| int signal, void *death_cookie, |
| int group_dead) |
| { |
| } |
| |
| #ifdef TIF_NOTIFY_RESUME |
| /** |
| * set_notify_resume - cause tracehook_notify_resume() to be called |
| * @task: task that will call tracehook_notify_resume() |
| * |
| * Calling this arranges that @task will call tracehook_notify_resume() |
| * before returning to user mode. If it's already running in user mode, |
| * it will enter the kernel and call tracehook_notify_resume() soon. |
| * If it's blocked, it will not be woken. |
| */ |
| static inline void set_notify_resume(struct task_struct *task) |
| { |
| if (!test_and_set_tsk_thread_flag(task, TIF_NOTIFY_RESUME)) |
| kick_process(task); |
| } |
| |
| /** |
| * tracehook_notify_resume - report when about to return to user mode |
| * @regs: user-mode registers of @current task |
| * |
| * This is called when %TIF_NOTIFY_RESUME has been set. Now we are |
| * about to return to user mode, and the user state in @regs can be |
| * inspected or adjusted. The caller in arch code has cleared |
| * %TIF_NOTIFY_RESUME before the call. If the flag gets set again |
| * asynchronously, this will be called again before we return to |
| * user mode. |
| * |
| * Called without locks. |
| */ |
| static inline void tracehook_notify_resume(struct pt_regs *regs) |
| { |
| } |
| #endif /* TIF_NOTIFY_RESUME */ |
| |
| #endif /* <linux/tracehook.h> */ |