160 lines
6.3 KiB
C
160 lines
6.3 KiB
C
/*
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* Access to user system call parameters and results
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*
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* Copyright (C) 2008-2009 Red Hat, Inc. All rights reserved.
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*
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* This copyrighted material is made available to anyone wishing to use,
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* modify, copy, or redistribute it subject to the terms and conditions
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* of the GNU General Public License v.2.
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*
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* This file is a stub providing documentation for what functions
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* asm-ARCH/syscall.h files need to define. Most arch definitions
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* will be simple inlines.
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*
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* All of these functions expect to be called with no locks,
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* and only when the caller is sure that the task of interest
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* cannot return to user mode while we are looking at it.
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*/
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#ifndef _ASM_SYSCALL_H
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#define _ASM_SYSCALL_H 1
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struct task_struct;
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struct pt_regs;
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/**
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* syscall_get_nr - find what system call a task is executing
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* @task: task of interest, must be blocked
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* @regs: task_pt_regs() of @task
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*
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* If @task is executing a system call or is at system call
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* tracing about to attempt one, returns the system call number.
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* If @task is not executing a system call, i.e. it's blocked
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* inside the kernel for a fault or signal, returns -1.
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*
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* Note this returns int even on 64-bit machines. Only 32 bits of
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* system call number can be meaningful. If the actual arch value
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* is 64 bits, this truncates to 32 bits so 0xffffffff means -1.
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*
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* It's only valid to call this when @task is known to be blocked.
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*/
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int syscall_get_nr(struct task_struct *task, struct pt_regs *regs);
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/**
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* syscall_rollback - roll back registers after an aborted system call
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* @task: task of interest, must be in system call exit tracing
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* @regs: task_pt_regs() of @task
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*
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* It's only valid to call this when @task is stopped for system
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* call exit tracing (due to TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT),
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* after tracehook_report_syscall_entry() returned nonzero to prevent
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* the system call from taking place.
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*
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* This rolls back the register state in @regs so it's as if the
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* system call instruction was a no-op. The registers containing
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* the system call number and arguments are as they were before the
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* system call instruction. This may not be the same as what the
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* register state looked like at system call entry tracing.
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*/
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void syscall_rollback(struct task_struct *task, struct pt_regs *regs);
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/**
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* syscall_get_error - check result of traced system call
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* @task: task of interest, must be blocked
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* @regs: task_pt_regs() of @task
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*
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* Returns 0 if the system call succeeded, or -ERRORCODE if it failed.
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*
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* It's only valid to call this when @task is stopped for tracing on exit
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* from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
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*/
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long syscall_get_error(struct task_struct *task, struct pt_regs *regs);
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/**
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* syscall_get_return_value - get the return value of a traced system call
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* @task: task of interest, must be blocked
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* @regs: task_pt_regs() of @task
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*
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* Returns the return value of the successful system call.
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* This value is meaningless if syscall_get_error() returned nonzero.
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*
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* It's only valid to call this when @task is stopped for tracing on exit
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* from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
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*/
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long syscall_get_return_value(struct task_struct *task, struct pt_regs *regs);
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/**
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* syscall_set_return_value - change the return value of a traced system call
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* @task: task of interest, must be blocked
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* @regs: task_pt_regs() of @task
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* @error: negative error code, or zero to indicate success
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* @val: user return value if @error is zero
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*
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* This changes the results of the system call that user mode will see.
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* If @error is zero, the user sees a successful system call with a
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* return value of @val. If @error is nonzero, it's a negated errno
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* code; the user sees a failed system call with this errno code.
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*
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* It's only valid to call this when @task is stopped for tracing on exit
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* from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
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*/
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void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
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int error, long val);
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/**
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* syscall_get_arguments - extract system call parameter values
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* @task: task of interest, must be blocked
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* @regs: task_pt_regs() of @task
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* @i: argument index [0,5]
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* @n: number of arguments; n+i must be [1,6].
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* @args: array filled with argument values
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*
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* Fetches @n arguments to the system call starting with the @i'th argument
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* (from 0 through 5). Argument @i is stored in @args[0], and so on.
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* An arch inline version is probably optimal when @i and @n are constants.
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*
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* It's only valid to call this when @task is stopped for tracing on
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* entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
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* It's invalid to call this with @i + @n > 6; we only support system calls
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* taking up to 6 arguments.
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*/
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void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
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unsigned int i, unsigned int n, unsigned long *args);
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/**
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* syscall_set_arguments - change system call parameter value
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* @task: task of interest, must be in system call entry tracing
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* @regs: task_pt_regs() of @task
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* @i: argument index [0,5]
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* @n: number of arguments; n+i must be [1,6].
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* @args: array of argument values to store
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*
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* Changes @n arguments to the system call starting with the @i'th argument.
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* Argument @i gets value @args[0], and so on.
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* An arch inline version is probably optimal when @i and @n are constants.
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*
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* It's only valid to call this when @task is stopped for tracing on
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* entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
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* It's invalid to call this with @i + @n > 6; we only support system calls
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* taking up to 6 arguments.
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*/
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void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
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unsigned int i, unsigned int n,
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const unsigned long *args);
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/**
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* syscall_get_arch - return the AUDIT_ARCH for the current system call
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* @task: task of interest, must be in system call entry tracing
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* @regs: task_pt_regs() of @task
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*
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* Returns the AUDIT_ARCH_* based on the system call convention in use.
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*
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* It's only valid to call this when @task is stopped on entry to a system
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* call, due to %TIF_SYSCALL_TRACE, %TIF_SYSCALL_AUDIT, or %TIF_SECCOMP.
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*
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* Architectures which permit CONFIG_HAVE_ARCH_SECCOMP_FILTER must
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* provide an implementation of this.
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*/
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int syscall_get_arch(struct task_struct *task, struct pt_regs *regs);
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#endif /* _ASM_SYSCALL_H */
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