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1/*
2 * Access to user system call parameters and results
3 *
4 * Copyright (C) 2008-2009 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 is a stub providing documentation for what functions
11 * asm-ARCH/syscall.h files need to define. Most arch definitions
12 * will be simple inlines.
13 *
14 * All of these functions expect to be called with no locks,
15 * and only when the caller is sure that the task of interest
16 * cannot return to user mode while we are looking at it.
17 */
18
19#ifndef _ASM_SYSCALL_H
20#define _ASM_SYSCALL_H 1
21
22struct task_struct;
23struct pt_regs;
24
25/**
26 * syscall_get_nr - find what system call a task is executing
27 * @task: task of interest, must be blocked
28 * @regs: task_pt_regs() of @task
29 *
30 * If @task is executing a system call or is at system call
31 * tracing about to attempt one, returns the system call number.
32 * If @task is not executing a system call, i.e. it's blocked
33 * inside the kernel for a fault or signal, returns -1.
34 *
35 * Note this returns int even on 64-bit machines. Only 32 bits of
36 * system call number can be meaningful. If the actual arch value
37 * is 64 bits, this truncates to 32 bits so 0xffffffff means -1.
38 *
39 * It's only valid to call this when @task is known to be blocked.
40 */
41int syscall_get_nr(struct task_struct *task, struct pt_regs *regs);
42
43/**
44 * syscall_rollback - roll back registers after an aborted system call
45 * @task: task of interest, must be in system call exit tracing
46 * @regs: task_pt_regs() of @task
47 *
48 * It's only valid to call this when @task is stopped for system
49 * call exit tracing (due to TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT),
50 * after tracehook_report_syscall_entry() returned nonzero to prevent
51 * the system call from taking place.
52 *
53 * This rolls back the register state in @regs so it's as if the
54 * system call instruction was a no-op. The registers containing
55 * the system call number and arguments are as they were before the
56 * system call instruction. This may not be the same as what the
57 * register state looked like at system call entry tracing.
58 */
59void syscall_rollback(struct task_struct *task, struct pt_regs *regs);
60
61/**
62 * syscall_get_error - check result of traced system call
63 * @task: task of interest, must be blocked
64 * @regs: task_pt_regs() of @task
65 *
66 * Returns 0 if the system call succeeded, or -ERRORCODE if it failed.
67 *
68 * It's only valid to call this when @task is stopped for tracing on exit
69 * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
70 */
71long syscall_get_error(struct task_struct *task, struct pt_regs *regs);
72
73/**
74 * syscall_get_return_value - get the return value of a traced system call
75 * @task: task of interest, must be blocked
76 * @regs: task_pt_regs() of @task
77 *
78 * Returns the return value of the successful system call.
79 * This value is meaningless if syscall_get_error() returned nonzero.
80 *
81 * It's only valid to call this when @task is stopped for tracing on exit
82 * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
83 */
84long syscall_get_return_value(struct task_struct *task, struct pt_regs *regs);
85
86/**
87 * syscall_set_return_value - change the return value of a traced system call
88 * @task: task of interest, must be blocked
89 * @regs: task_pt_regs() of @task
90 * @error: negative error code, or zero to indicate success
91 * @val: user return value if @error is zero
92 *
93 * This changes the results of the system call that user mode will see.
94 * If @error is zero, the user sees a successful system call with a
95 * return value of @val. If @error is nonzero, it's a negated errno
96 * code; the user sees a failed system call with this errno code.
97 *
98 * It's only valid to call this when @task is stopped for tracing on exit
99 * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
100 */
101void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
102 int error, long val);
103
104/**
105 * syscall_get_arguments - extract system call parameter values
106 * @task: task of interest, must be blocked
107 * @regs: task_pt_regs() of @task
108 * @i: argument index [0,5]
109 * @n: number of arguments; n+i must be [1,6].
110 * @args: array filled with argument values
111 *
112 * Fetches @n arguments to the system call starting with the @i'th argument
113 * (from 0 through 5). Argument @i is stored in @args[0], and so on.
114 * An arch inline version is probably optimal when @i and @n are constants.
115 *
116 * It's only valid to call this when @task is stopped for tracing on
117 * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
118 * It's invalid to call this with @i + @n > 6; we only support system calls
119 * taking up to 6 arguments.
120 */
121void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
122 unsigned int i, unsigned int n, unsigned long *args);
123
124/**
125 * syscall_set_arguments - change system call parameter value
126 * @task: task of interest, must be in system call entry tracing
127 * @regs: task_pt_regs() of @task
128 * @i: argument index [0,5]
129 * @n: number of arguments; n+i must be [1,6].
130 * @args: array of argument values to store
131 *
132 * Changes @n arguments to the system call starting with the @i'th argument.
133 * Argument @i gets value @args[0], and so on.
134 * An arch inline version is probably optimal when @i and @n are constants.
135 *
136 * It's only valid to call this when @task is stopped for tracing on
137 * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
138 * It's invalid to call this with @i + @n > 6; we only support system calls
139 * taking up to 6 arguments.
140 */
141void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
142 unsigned int i, unsigned int n,
143 const unsigned long *args);
144
145#endif /* _ASM_SYSCALL_H */
1/*
2 * Access to user system call parameters and results
3 *
4 * Copyright (C) 2008-2009 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 is a stub providing documentation for what functions
11 * asm-ARCH/syscall.h files need to define. Most arch definitions
12 * will be simple inlines.
13 *
14 * All of these functions expect to be called with no locks,
15 * and only when the caller is sure that the task of interest
16 * cannot return to user mode while we are looking at it.
17 */
18
19#ifndef _ASM_SYSCALL_H
20#define _ASM_SYSCALL_H 1
21
22struct task_struct;
23struct pt_regs;
24
25/**
26 * syscall_get_nr - find what system call a task is executing
27 * @task: task of interest, must be blocked
28 * @regs: task_pt_regs() of @task
29 *
30 * If @task is executing a system call or is at system call
31 * tracing about to attempt one, returns the system call number.
32 * If @task is not executing a system call, i.e. it's blocked
33 * inside the kernel for a fault or signal, returns -1.
34 *
35 * Note this returns int even on 64-bit machines. Only 32 bits of
36 * system call number can be meaningful. If the actual arch value
37 * is 64 bits, this truncates to 32 bits so 0xffffffff means -1.
38 *
39 * It's only valid to call this when @task is known to be blocked.
40 */
41int syscall_get_nr(struct task_struct *task, struct pt_regs *regs);
42
43/**
44 * syscall_rollback - roll back registers after an aborted system call
45 * @task: task of interest, must be in system call exit tracing
46 * @regs: task_pt_regs() of @task
47 *
48 * It's only valid to call this when @task is stopped for system
49 * call exit tracing (due to TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT),
50 * after tracehook_report_syscall_entry() returned nonzero to prevent
51 * the system call from taking place.
52 *
53 * This rolls back the register state in @regs so it's as if the
54 * system call instruction was a no-op. The registers containing
55 * the system call number and arguments are as they were before the
56 * system call instruction. This may not be the same as what the
57 * register state looked like at system call entry tracing.
58 */
59void syscall_rollback(struct task_struct *task, struct pt_regs *regs);
60
61/**
62 * syscall_get_error - check result of traced system call
63 * @task: task of interest, must be blocked
64 * @regs: task_pt_regs() of @task
65 *
66 * Returns 0 if the system call succeeded, or -ERRORCODE if it failed.
67 *
68 * It's only valid to call this when @task is stopped for tracing on exit
69 * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
70 */
71long syscall_get_error(struct task_struct *task, struct pt_regs *regs);
72
73/**
74 * syscall_get_return_value - get the return value of a traced system call
75 * @task: task of interest, must be blocked
76 * @regs: task_pt_regs() of @task
77 *
78 * Returns the return value of the successful system call.
79 * This value is meaningless if syscall_get_error() returned nonzero.
80 *
81 * It's only valid to call this when @task is stopped for tracing on exit
82 * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
83 */
84long syscall_get_return_value(struct task_struct *task, struct pt_regs *regs);
85
86/**
87 * syscall_set_return_value - change the return value of a traced system call
88 * @task: task of interest, must be blocked
89 * @regs: task_pt_regs() of @task
90 * @error: negative error code, or zero to indicate success
91 * @val: user return value if @error is zero
92 *
93 * This changes the results of the system call that user mode will see.
94 * If @error is zero, the user sees a successful system call with a
95 * return value of @val. If @error is nonzero, it's a negated errno
96 * code; the user sees a failed system call with this errno code.
97 *
98 * It's only valid to call this when @task is stopped for tracing on exit
99 * from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
100 */
101void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
102 int error, long val);
103
104/**
105 * syscall_get_arguments - extract system call parameter values
106 * @task: task of interest, must be blocked
107 * @regs: task_pt_regs() of @task
108 * @i: argument index [0,5]
109 * @n: number of arguments; n+i must be [1,6].
110 * @args: array filled with argument values
111 *
112 * Fetches @n arguments to the system call starting with the @i'th argument
113 * (from 0 through 5). Argument @i is stored in @args[0], and so on.
114 * An arch inline version is probably optimal when @i and @n are constants.
115 *
116 * It's only valid to call this when @task is stopped for tracing on
117 * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
118 * It's invalid to call this with @i + @n > 6; we only support system calls
119 * taking up to 6 arguments.
120 */
121void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
122 unsigned int i, unsigned int n, unsigned long *args);
123
124/**
125 * syscall_set_arguments - change system call parameter value
126 * @task: task of interest, must be in system call entry tracing
127 * @regs: task_pt_regs() of @task
128 * @i: argument index [0,5]
129 * @n: number of arguments; n+i must be [1,6].
130 * @args: array of argument values to store
131 *
132 * Changes @n arguments to the system call starting with the @i'th argument.
133 * Argument @i gets value @args[0], and so on.
134 * An arch inline version is probably optimal when @i and @n are constants.
135 *
136 * It's only valid to call this when @task is stopped for tracing on
137 * entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
138 * It's invalid to call this with @i + @n > 6; we only support system calls
139 * taking up to 6 arguments.
140 */
141void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
142 unsigned int i, unsigned int n,
143 const unsigned long *args);
144
145/**
146 * syscall_get_arch - return the AUDIT_ARCH for the current system call
147 *
148 * Returns the AUDIT_ARCH_* based on the system call convention in use.
149 *
150 * It's only valid to call this when current is stopped on entry to a system
151 * call, due to %TIF_SYSCALL_TRACE, %TIF_SYSCALL_AUDIT, or %TIF_SECCOMP.
152 *
153 * Architectures which permit CONFIG_HAVE_ARCH_SECCOMP_FILTER must
154 * provide an implementation of this.
155 */
156int syscall_get_arch(void);
157#endif /* _ASM_SYSCALL_H */