1.\" $NetBSD: mprotect.2,v 1.29 2019/09/09 07:46:49 wiz Exp $ 2.\" 3.\" Copyright (c) 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" @(#)mprotect.2 8.1 (Berkeley) 6/9/93 31.\" 32.Dd September 8, 2019 33.Dt MPROTECT 2 34.Os 35.Sh NAME 36.Nm mprotect 37.Nd control the protection of pages 38.Sh LIBRARY 39.Lb libc 40.Sh SYNOPSIS 41.In sys/mman.h 42.Ft int 43.Fn mprotect "void *addr" "size_t len" "int prot" 44.Sh DESCRIPTION 45The 46.Nm 47system call 48changes the specified pages to have protection 49.Fa prot . 50Not all implementations will guarantee protection on a page basis; 51the granularity of protection changes may be as large as an entire region. 52.Pp 53The protections (region accessibility) are specified in the 54.Fa prot 55argument by 56.Tn OR Ns 'ing 57the following values: 58.Bl -tag -width "Dv MAP_WRITE" -offset indent 59.It Dv PROT_EXEC 60Pages may be executed. 61.It Dv PROT_READ 62Pages may be read. 63.It Dv PROT_WRITE 64Pages may be written. 65.It Dv PROT_NONE 66Placeholder when requesting no access permission. 67.El 68.Sh RETURN VALUES 69Upon successful completion, 70a value of 0 is returned. 71Otherwise, a value of \-1 is returned and 72.Va errno 73is set to indicate the error. 74.Sh ERRORS 75.Bl -tag -width Er 76.It Bq Er EACCES 77A memory protection violation occurred. 78.Pp 79The 80.Dv PROT_EXEC 81flag was attempted on pages which belong to a file system mounted with the 82.Dv NOEXEC 83flag. 84.Pp 85The new protection is less restrictive than the protection originally 86set with 87.Xr mmap 2 . 88.Pp 89PaX mprotect restrictions prohibit the requested protection. 90.It Bq Er EINVAL 91An invalid memory range, or invalid parameters were provided. 92.It Bq Er ENOMEM 93A resource shortage occurred while internally calling 94.Xr uvm_map_protect 9 . 95.El 96.Sh SEE ALSO 97.Xr madvise 2 , 98.Xr mincore 2 , 99.Xr msync 2 , 100.Xr munmap 2 101.Sh HISTORY 102The 103.Nm 104function first appeared in SunOS 4.0 and subsequently 105.Bx 4.4 . 106