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88ac2921 RM |
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> | |
6341c393 RM |
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 | } | |
88ac2921 | 97 | |
30199f5a RM |
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 | ||
88ac2921 | 113 | #endif /* <linux/tracehook.h> */ |