acb8858f05
From POSIX,
[ENOTSUP]
The implementation does not support the combination of accesses
requested in the prot argument.
This fits the case that prot contains permissions which are not a subset
of prot_max.
Reviewed by: brooks, cem
Relnotes: Yes
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D23843
130 lines
3.5 KiB
Groff
130 lines
3.5 KiB
Groff
.\" Copyright (c) 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)mprotect.2 8.1 (Berkeley) 6/9/93
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.\" $FreeBSD$
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.\"
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.Dd February 26, 2020
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.Dt MPROTECT 2
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.Os
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.Sh NAME
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.Nm mprotect
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.Nd control the protection of pages
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In sys/mman.h
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.Ft int
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.Fn mprotect "void *addr" "size_t len" "int prot"
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.Sh DESCRIPTION
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The
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.Fn mprotect
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system call
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changes the specified pages to have protection
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.Fa prot .
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Not all implementations will guarantee protection on a page basis;
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the granularity of protection changes may be as large as an entire region.
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A region is the virtual address space defined by the start
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and end addresses of a
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.Vt "struct vm_map_entry" .
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.Pp
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Currently these protection bits are known,
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which can be combined, OR'd together:
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.Pp
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.Bl -tag -width ".Dv PROT_WRITE" -compact
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.It Dv PROT_NONE
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No permissions at all.
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.It Dv PROT_READ
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The pages can be read.
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.It Dv PROT_WRITE
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The pages can be written.
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.It Dv PROT_EXEC
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The pages can be executed.
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.El
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.Pp
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In addition to these protection flags,
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.Fx
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provides the ability to set the maximum protection of a region
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(which prevents
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.Nm
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from upgrading the permissions).
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This is accomplished by
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.Em or Ns 'ing
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one or more
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.Dv PROT_
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values wrapped in the
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.Dv PROT_MAX()
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macro into the
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.Fa prot
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argument.
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.Sh RETURN VALUES
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.Rv -std mprotect
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.Sh ERRORS
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The
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.Fn mprotect
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system call will fail if:
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.Bl -tag -width Er
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.It Bq Er EACCES
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The calling process was not allowed to change
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the protection to the value specified by
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the
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.Fa prot
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argument.
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.It Bq Er EINVAL
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The virtual address range specified by the
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.Fa addr
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and
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.Fa len
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arguments is not valid.
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.It Bq Er EINVAL
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The
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.Fa prot
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argument contains unhandled bits.
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.It Bq Er ENOTSUP
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The
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.Fa prot
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argument contains permissions which are not a subset of the specified
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maximum permissions.
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.El
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.Sh SEE ALSO
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.Xr madvise 2 ,
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.Xr mincore 2 ,
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.Xr msync 2 ,
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.Xr munmap 2
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.Sh HISTORY
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The
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.Fn mprotect
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system call was first documented in
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.Bx 4.2
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and first appeared in
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.Bx 4.4 .
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.Pp
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The
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.Dv PROT_MAX
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functionality was introduced in
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.Fx 13 .
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