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.\" 30.Dd September 7, 2021 31.Dt MPROTECT 2 32.Os 33.Sh NAME 34.Nm mprotect 35.Nd control the protection of pages 36.Sh LIBRARY 37.Lb libc 38.Sh SYNOPSIS 39.In sys/mman.h 40.Ft int 41.Fn mprotect "void *addr" "size_t len" "int prot" 42.Sh DESCRIPTION 43The 44.Fn mprotect 45system call 46changes the specified pages to have protection 47.Fa prot . 48.Pp 49The 50.Fa prot 51argument shall be 52.Dv PROT_NONE 53(no permissions at all) 54or the bitwise 55.Em or 56of one or more of the following values: 57.Pp 58.Bl -tag -width ".Dv PROT_WRITE" -compact 59.It Dv PROT_READ 60The pages can be read. 61.It Dv PROT_WRITE 62The pages can be written. 63.It Dv PROT_EXEC 64The pages can be executed. 65.El 66.Pp 67In addition to these standard protection flags, 68the 69.Fx 70implementation of 71.Fn mprotect 72provides the ability to set the maximum protection of a region 73(which prevents 74.Nm 75from adding to the permissions later). 76This is accomplished by bitwise 77.Em or Ns 'ing 78one or more 79.Dv PROT_ 80values wrapped in the 81.Dv PROT_MAX() 82macro into the 83.Fa prot 84argument. 85.Sh RETURN VALUES 86.Rv -std mprotect 87.Sh ERRORS 88The 89.Fn mprotect 90system call will fail if: 91.Bl -tag -width Er 92.It Bq Er EACCES 93The calling process was not allowed to change 94the protection to the value specified by 95the 96.Fa prot 97argument. 98.It Bq Er EINVAL 99The virtual address range specified by the 100.Fa addr 101and 102.Fa len 103arguments is not valid. 104.It Bq Er EINVAL 105The 106.Fa prot 107argument contains unhandled bits. 108.It Bq Er ENOTSUP 109The 110.Fa prot 111argument contains permissions which are not a subset of the specified 112maximum permissions. 113.El 114.Sh SEE ALSO 115.Xr madvise 2 , 116.Xr mincore 2 , 117.Xr msync 2 , 118.Xr munmap 2 119.Sh HISTORY 120The 121.Fn mprotect 122system call was first documented in 123.Bx 4.2 124and first appeared in 125.Bx 4.4 . 126.Pp 127The 128.Dv PROT_MAX 129functionality was introduced in 130.Fx 13 . 131