Roland McGrath | 88ac292 | 2008-07-25 19:45:43 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Tracing hooks |
| 3 | * |
| 4 | * Copyright (C) 2008 Red Hat, Inc. All rights reserved. |
| 5 | * |
| 6 | * This copyrighted material is made available to anyone wishing to use, |
| 7 | * modify, copy, or redistribute it subject to the terms and conditions |
| 8 | * of the GNU General Public License v.2. |
| 9 | * |
| 10 | * This file defines hook entry points called by core code where |
| 11 | * user tracing/debugging support might need to do something. These |
| 12 | * entry points are called tracehook_*(). Each hook declared below |
| 13 | * has a detailed kerneldoc comment giving the context (locking et |
| 14 | * al) from which it is called, and the meaning of its return value. |
| 15 | * |
| 16 | * Each function here typically has only one call site, so it is ok |
| 17 | * to have some nontrivial tracehook_*() inlines. In all cases, the |
| 18 | * fast path when no tracing is enabled should be very short. |
| 19 | * |
| 20 | * The purpose of this file and the tracehook_* layer is to consolidate |
| 21 | * the interface that the kernel core and arch code uses to enable any |
| 22 | * user debugging or tracing facility (such as ptrace). The interfaces |
| 23 | * here are carefully documented so that maintainers of core and arch |
| 24 | * code do not need to think about the implementation details of the |
| 25 | * tracing facilities. Likewise, maintainers of the tracing code do not |
| 26 | * need to understand all the calling core or arch code in detail, just |
| 27 | * documented circumstances of each call, such as locking conditions. |
| 28 | * |
| 29 | * If the calling core code changes so that locking is different, then |
| 30 | * it is ok to change the interface documented here. The maintainer of |
| 31 | * core code changing should notify the maintainers of the tracing code |
| 32 | * that they need to work out the change. |
| 33 | * |
| 34 | * Some tracehook_*() inlines take arguments that the current tracing |
| 35 | * implementations might not necessarily use. These function signatures |
| 36 | * are chosen to pass in all the information that is on hand in the |
| 37 | * caller and might conceivably be relevant to a tracer, so that the |
| 38 | * core code won't have to be updated when tracing adds more features. |
| 39 | * If a call site changes so that some of those parameters are no longer |
| 40 | * already on hand without extra work, then the tracehook_* interface |
| 41 | * can change so there is no make-work burden on the core code. The |
| 42 | * maintainer of core code changing should notify the maintainers of the |
| 43 | * tracing code that they need to work out the change. |
| 44 | */ |
| 45 | |
| 46 | #ifndef _LINUX_TRACEHOOK_H |
| 47 | #define _LINUX_TRACEHOOK_H 1 |
| 48 | |
| 49 | #include <linux/sched.h> |
| 50 | #include <linux/ptrace.h> |
Roland McGrath | 6341c39 | 2008-07-25 19:45:44 -0700 | [diff] [blame] | 51 | #include <linux/security.h> |
| 52 | struct linux_binprm; |
| 53 | |
| 54 | /** |
| 55 | * tracehook_unsafe_exec - check for exec declared unsafe due to tracing |
| 56 | * @task: current task doing exec |
| 57 | * |
| 58 | * Return %LSM_UNSAFE_* bits applied to an exec because of tracing. |
| 59 | * |
| 60 | * Called with task_lock() held on @task. |
| 61 | */ |
| 62 | static inline int tracehook_unsafe_exec(struct task_struct *task) |
| 63 | { |
| 64 | int unsafe = 0; |
| 65 | int ptrace = task_ptrace(task); |
| 66 | if (ptrace & PT_PTRACED) { |
| 67 | if (ptrace & PT_PTRACE_CAP) |
| 68 | unsafe |= LSM_UNSAFE_PTRACE_CAP; |
| 69 | else |
| 70 | unsafe |= LSM_UNSAFE_PTRACE; |
| 71 | } |
| 72 | return unsafe; |
| 73 | } |
| 74 | |
| 75 | /** |
| 76 | * tracehook_report_exec - a successful exec was completed |
| 77 | * @fmt: &struct linux_binfmt that performed the exec |
| 78 | * @bprm: &struct linux_binprm containing exec details |
| 79 | * @regs: user-mode register state |
| 80 | * |
| 81 | * An exec just completed, we are shortly going to return to user mode. |
| 82 | * The freshly initialized register state can be seen and changed in @regs. |
| 83 | * The name, file and other pointers in @bprm are still on hand to be |
| 84 | * inspected, but will be freed as soon as this returns. |
| 85 | * |
| 86 | * Called with no locks, but with some kernel resources held live |
| 87 | * and a reference on @fmt->module. |
| 88 | */ |
| 89 | static inline void tracehook_report_exec(struct linux_binfmt *fmt, |
| 90 | struct linux_binprm *bprm, |
| 91 | struct pt_regs *regs) |
| 92 | { |
| 93 | if (!ptrace_event(PT_TRACE_EXEC, PTRACE_EVENT_EXEC, 0) && |
| 94 | unlikely(task_ptrace(current) & PT_PTRACED)) |
| 95 | send_sig(SIGTRAP, current, 0); |
| 96 | } |
Roland McGrath | 88ac292 | 2008-07-25 19:45:43 -0700 | [diff] [blame] | 97 | |
Roland McGrath | 30199f5 | 2008-07-25 19:45:46 -0700 | [diff] [blame^] | 98 | /** |
| 99 | * tracehook_report_exit - task has begun to exit |
| 100 | * @exit_code: pointer to value destined for @current->exit_code |
| 101 | * |
| 102 | * @exit_code points to the value passed to do_exit(), which tracing |
| 103 | * might change here. This is almost the first thing in do_exit(), |
| 104 | * before freeing any resources or setting the %PF_EXITING flag. |
| 105 | * |
| 106 | * Called with no locks held. |
| 107 | */ |
| 108 | static inline void tracehook_report_exit(long *exit_code) |
| 109 | { |
| 110 | ptrace_event(PT_TRACE_EXIT, PTRACE_EVENT_EXIT, *exit_code); |
| 111 | } |
| 112 | |
Roland McGrath | 88ac292 | 2008-07-25 19:45:43 -0700 | [diff] [blame] | 113 | #endif /* <linux/tracehook.h> */ |