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.Dd September 7, 2021 29.Dt MPROTECT 2 30.Os 31.Sh NAME 32.Nm mprotect 33.Nd control the protection of pages 34.Sh LIBRARY 35.Lb libc 36.Sh SYNOPSIS 37.In sys/mman.h 38.Ft int 39.Fn mprotect "void *addr" "size_t len" "int prot" 40.Sh DESCRIPTION 41The 42.Fn mprotect 43system call 44changes the specified pages to have protection 45.Fa prot . 46.Pp 47The 48.Fa prot 49argument shall be 50.Dv PROT_NONE 51(no permissions at all) 52or the bitwise 53.Em or 54of one or more of the following values: 55.Pp 56.Bl -tag -width ".Dv PROT_WRITE" -compact 57.It Dv PROT_READ 58The pages can be read. 59.It Dv PROT_WRITE 60The pages can be written. 61.It Dv PROT_EXEC 62The pages can be executed. 63.El 64.Pp 65In addition to these standard protection flags, 66the 67.Fx 68implementation of 69.Fn mprotect 70provides the ability to set the maximum protection of a region 71(which prevents 72.Nm 73from adding to the permissions later). 74This is accomplished by bitwise 75.Em or Ns 'ing 76one or more 77.Dv PROT_ 78values wrapped in the 79.Dv PROT_MAX() 80macro into the 81.Fa prot 82argument. 83.Sh RETURN VALUES 84.Rv -std mprotect 85.Sh ERRORS 86The 87.Fn mprotect 88system call will fail if: 89.Bl -tag -width Er 90.It Bq Er EACCES 91The calling process was not allowed to change 92the protection to the value specified by 93the 94.Fa prot 95argument. 96.It Bq Er EINVAL 97The virtual address range specified by the 98.Fa addr 99and 100.Fa len 101arguments is not valid. 102.It Bq Er EINVAL 103The 104.Fa prot 105argument contains unhandled bits. 106.It Bq Er ENOTSUP 107The 108.Fa prot 109argument contains permissions which are not a subset of the specified 110maximum permissions. 111.El 112.Sh SEE ALSO 113.Xr madvise 2 , 114.Xr mincore 2 , 115.Xr msync 2 , 116.Xr munmap 2 117.Sh HISTORY 118The 119.Fn mprotect 120system call was first documented in 121.Bx 4.2 122and first appeared in 123.Bx 4.4 . 124.Pp 125The 126.Dv PROT_MAX 127functionality was introduced in 128.Fx 13 . 129