1.\" Copyright (c) 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)mprotect.2 8.1 (Berkeley) 6/9/93 29.\" $FreeBSD$ 30.\" 31.Dd August 3, 2016 32.Dt MPROTECT 2 33.Os 34.Sh NAME 35.Nm mprotect 36.Nd control the protection of pages 37.Sh LIBRARY 38.Lb libc 39.Sh SYNOPSIS 40.In sys/mman.h 41.Ft int 42.Fn mprotect "void *addr" "size_t len" "int prot" 43.Sh DESCRIPTION 44The 45.Fn mprotect 46system call 47changes the specified pages to have protection 48.Fa prot . 49Not all implementations will guarantee protection on a page basis; 50the granularity of protection changes may be as large as an entire region. 51A region is the virtual address space defined by the start 52and end addresses of a 53.Vt "struct vm_map_entry" . 54.Pp 55Currently these protection bits are known, 56which can be combined, OR'd together: 57.Pp 58.Bl -tag -width ".Dv PROT_WRITE" -compact 59.It Dv PROT_NONE 60No permissions at all. 61.It Dv PROT_READ 62The pages can be read. 63.It Dv PROT_WRITE 64The pages can be written. 65.It Dv PROT_EXEC 66The pages can be executed. 67.El 68.Sh RETURN VALUES 69.Rv -std mprotect 70.Sh ERRORS 71The 72.Fn mprotect 73system call will fail if: 74.Bl -tag -width Er 75.It Bq Er EINVAL 76The virtual address range specified by the 77.Fa addr 78and 79.Fa len 80arguments is not valid. 81.It Bq Er EACCES 82The calling process was not allowed to change 83the protection to the value specified by 84the 85.Fa prot 86argument. 87.El 88.Sh SEE ALSO 89.Xr madvise 2 , 90.Xr mincore 2 , 91.Xr msync 2 , 92.Xr munmap 2 93.Sh HISTORY 94The 95.Fn mprotect 96system call first appeared in 97.Bx 4.4 . 98