78 lines
2.2 KiB
Groff
78 lines
2.2 KiB
Groff
.\" $OpenBSD: pinsyscall.2,v 1.5 2023/02/21 19:49:50 jmc Exp $
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.\"
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.\" Copyright (c) 2023 Theo de Raadt <deraadt@openbsd.org>
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.\"
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.\" Permission to use, copy, modify, and distribute this software for any
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.\" purpose with or without fee is hereby granted, provided that the above
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.\" copyright notice and this permission notice appear in all copies.
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.\"
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.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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.\"
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.Dd $Mdocdate: February 21 2023 $
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.Dt PINSYSCALL 2
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.Os
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.Sh NAME
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.Nm pinsyscall
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.Nd specify the call stub for a specific system call
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.Sh SYNOPSIS
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.In sys/types.h
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.In sys/syscall.h
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.Ft int
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.Fn pinsyscall "int syscall" "void *start" "size_t len"
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.Sh DESCRIPTION
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The
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.Fn pinsyscall
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system call specifies the
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.Va start
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to
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.Va start + len
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range in the address space where the call stub for the specified
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.Va syscall
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resides.
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This range is typically under 80 bytes long, and varies by architecture.
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.Pp
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Only the
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.Va SYS_execve
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system call is currently supported.
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The shared library linker
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.Pa ld.so
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automatically tells the kernel about
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.Va SYS_execve
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at startup.
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For static binaries, libc initialization performs the same action.
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.Pp
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Once the kernel knows the specific location in the address space where
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that system call must be entered from, any attempt to use a system-call
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entry instruction to perform the specified
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.Va syscall
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from a different address range will deliver
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.Dv SIGABRT .
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.Sh RETURN VALUES
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.Rv -std
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.Sh ERRORS
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.Fn pinsyscall
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will fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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Unsupported syscall.
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.It Bq Er EFAULT
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The range between
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.Va start
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and
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.Va start + len
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is not in the address space.
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.It Bq Er EPERM
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The range for the specified syscall has been previously set.
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.El
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.Sh HISTORY
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The
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.Fn pinsyscall
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system call first appeared in
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.Ox 7.3 .
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