(split) Apply minor changes from v3.32 to v3.35 in the upstream.

[linuxjm/LDP_man-pages.git] / draft / man2 / mprotect.2

.\" -*- nroff -*-
.\" Copyright (C) 2007 Michael Kerrisk <mtk.manpages@gmail.com>
.\" and Copyright (C) 1995 Michael Shields <shields@tembel.org>.
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and author of this work.
.\"
.\" Modified 1996-10-22 by Eric S. Raymond <esr@thyrsus.com>
.\" Modified 1997-05-31 by Andries Brouwer <aeb@cwi.nl>
.\" Modified 2003-08-24 by Andries Brouwer <aeb@cwi.nl>
.\" Modified 2004-08-16 by Andi Kleen <ak@muc.de>
.\" 2007-06-02, mtk: Fairly substantial rewrites and additions, and
.\" a much improved example program.
.\"
.\" Japanese Version Copyright (c) 1997 HANATAKA Shinya
.\"         all rights reserved.
.\" Translated 1997-06-01, HANATAKA Shinya <hanataka@abyss.rim.or.jp>
.\" Updated and revised 2003-10-24, Suzuki Takashi.
.\" Updated & Modified 2005-02-08, Yuichi SATO <ysato444@yahoo.co.jp>
.\" Updated & Modified 2005-10-15, Yuichi SATO
.\" Updated 2007-06-11, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>, LDP v2.54
.\"
.\"WORD: bitwise-or             ¥Ó¥Ã¥È¤´¤È¤ÎÏÀÍýÏÂ
.\"WORD: protection             ¥¢¥¯¥»¥¹Êݸî
.\"WORD: read-only              Æɤ߼è¤êÀìÍÑ
.\"
.TH MPROTECT 2 2011-09-08 "Linux" "Linux Programmer's Manual"
.\"O .SH NAME
.SH ̾Á°
.\"O mprotect \- set protection on a region of memory
mprotect \- ¥á¥â¥êÎΰè¤ÎÊݸî¤òÀßÄꤹ¤ë
.\"O .SH SYNOPSIS
.SH ½ñ¼°
.nf
.B #include <sys/mman.h>
.sp
.BI "int mprotect(const void *" addr ", size_t " len ", int " prot );
.fi
.\"O .SH DESCRIPTION
.SH ÀâÌÀ
.\"O .BR mprotect ()
.\"O changes protection for the calling process's memory page(s)
.\"O containing any part of the address range in the
.\"O interval [\fIaddr\fP,\ \fIaddr\fP+\fIlen\fP\-1].
.\"O .I addr
.\"O must be aligned to a page boundary.
.BR mprotect ()
¤Ï¡¢¶è´Ö [\fIaddr\fP,\ \fIaddr\fP+\fIlen\fP\-1] ¤Î¥¢¥É¥ì¥¹ÈϰϤò´Þ¤à
¸Æ¤Ó½Ð¤·¸µ¤Î¥×¥í¥»¥¹¤Î¥á¥â¥ê¥Ú¡¼¥¸¤Î¥¢¥¯¥»¥¹Êݸî¤òÊѹ¹¤¹¤ë¡£
.I addr
¤Ï¥Ú¡¼¥¸¶­³¦¤Ë°ìÃפ·¤Æ¤¤¤Ê¤±¤ì¤Ð¤Ê¤é¤Ê¤¤¡£

.\"O If the calling process tries to access memory in a manner
.\"O that violates the protection, then the kernel generates a
.\"O .B SIGSEGV
.\"O signal for the process.
¸Æ¤Ó½Ð¤·¸µ¤Î¥×¥í¥»¥¹¤¬¥¢¥¯¥»¥¹Êݸî¤Ë°ãÈ¿¤¹¤ë¤è¤¦¤Ê¥á¥â¥ê¥¢¥¯¥»¥¹¤ò
¹Ô¤ª¤¦¤È¤¹¤ë¤È¡¢¥«¡¼¥Í¥ë¤Ï¥·¥°¥Ê¥ë
.B SIGSEGV
¤ò¤½¤Î¥×¥í¥»¥¹¤ËÂФ·¤ÆÀ¸À®¤¹¤ë¡£
.PP
.\"O .I prot
.\"O is either
.\"O .B PROT_NONE
.\"O or a bitwise-or of the other values in the following list:
.I prot
¤Ë¤Ï¡¢
.B PROT_NONE
¤«¡¢°Ê²¼¤Î¥ê¥¹¥È¤Î
.B PROT_NONE
°Ê³°¤ÎÃͤò¥Ó¥Ã¥ÈËè¤ÎÏÀÍýÏ (bitwize-or) ¤Ç»ØÄꤹ¤ë:
.TP 1.1i
.B PROT_NONE
.\"O The memory cannot be accessed at all.
¤½¤Î¥á¥â¥ê¤Ë¤ÏÁ´¤¯¥¢¥¯¥»¥¹¤Ç¤­¤Ê¤¤¡£
.TP
.B PROT_READ
.\"O The memory can be read.
¤½¤Î¥á¥â¥ê¤òÆɤ߼è¤ë¤³¤È¤¬¤Ç¤­¤ë¡£
.TP
.B PROT_WRITE
.\"O The memory can be modified.
¤½¤Î¥á¥â¥ê¤òÊѹ¹¤Ç¤­¤ë¡£
.TP
.B PROT_EXEC
.\"O The memory can be executed.
¤½¤Î¥á¥â¥ê¤Ï¼Â¹Ô²Äǽ¤Ç¤¢¤ë¡£
.\" FIXME
.\" Document PROT_GROWSUP and PROT_GROWSDOWN
.\"O .SH "RETURN VALUE"
.SH ÊÖ¤êÃÍ
.\"O On success,
.\"O .BR mprotect ()
.\"O returns zero.
.\"O On error, \-1 is returned, and
.\"O .I errno
.\"O is set appropriately.
À®¸ù¤·¤¿¾ì¹ç¡¢
.BR mprotect ()
¤Ï 0 ¤òÊÖ¤¹¡£¥¨¥é¡¼¤Î¾ì¹ç¤Ï \-1 ¤¬Ê֤ꡢ
.I errno
¤¬Å¬ÀÚ¤ËÀßÄꤵ¤ì¤ë¡£
.\"O .SH ERRORS
.SH ¥¨¥é¡¼
.TP
.B EACCES
.\"O The memory cannot be given the specified access.
.\"O This can happen, for example, if you
.\"O .BR mmap (2)
.\"O a file to which you have read-only access, then ask
.\"O .BR mprotect ()
.\"O to mark it
.\"O .BR PROT_WRITE .
»ØÄꤵ¤ì¤¿¥¢¥¯¥»¥¹¤ò¥á¥â¥ê¤ËÀßÄꤹ¤ë¤³¤È¤¬¤Ç¤­¤Ê¤¤¡£
¤³¤ì¤Ï¡¢Î㤨¤Ð
¥Õ¥¡¥¤¥ë¤òÆɤ߼è¤êÀìÍѤÇ
.BR mmap (2)
¤·¤Æ¤ª¤ê¡¢¤½¤ÎÎΰè¤ËÂФ·¤Æ
.BR mprotect ()
¤ò¸Æ¤Ó½Ð¤·¤Æ
.B PROT_WRITE
¤ËÀßÄꤷ¤è¤¦¤È¤·¤¿¾ì¹ç¤ËȯÀ¸¤¹¤ë¡£
.TP
.B EINVAL
.\"O \fIaddr\fP is not a valid pointer,
.\"O or not a multiple of the system page size.
\fIaddr\fP ¤¬Í­¸ú¤Ê¥Ý¥¤¥ó¥¿¤Ç¤Ê¤¤¤«¡¢
¥·¥¹¥Æ¥à¤Î¥Ú¡¼¥¸¥µ¥¤¥º¤ÎÇÜ¿ô¤Ç¤Ê¤¤¡£
.\" Or: both PROT_GROWSUP and PROT_GROWSDOWN were specified in 'prot'.
.TP
.B ENOMEM
.\"O Internal kernel structures could not be allocated.
¥«¡¼¥Í¥ëÆâÉô¤Î¹½Â¤ÂΤò³ä¤êÅö¤Æ¤ë¤³¤È¤¬¤Ç¤­¤Ê¤«¤Ã¤¿¡£
.TP
.B ENOMEM
.\"O Addresses in the range
.\"O .RI [ addr ,
.\"O .IR addr + len \-1]
.\"O are invalid for the address space of the process,
.\"O or specify one or more pages that are not mapped.
.\"O (Before kernel 2.4.19, the error
.\"O .BR EFAULT
.\"O was incorrectly produced for these cases.)
.RI [ addr ,
.IR addr + len \-1]
¤È¤¤¤¦ÈϰϤΥ¢¥É¥ì¥¹¤¬¥×¥í¥»¥¹¤Î¥¢¥É¥ì¥¹¶õ´Ö¤È¤·¤ÆÉÔÀµ¤Ç¤¢¤ë¤«¡¢
¤½¤ÎÈϰϤΥ¢¥É¥ì¥¹¤¬¥Þ¥Ã¥×¤µ¤ì¤Æ¤¤¤Ê¤¤ 1 ¤Ä°Ê¾å¤Î¥Ú¡¼¥¸¤ò»Ø¤·¤Æ¤¤¤ë
(¥«¡¼¥Í¥ë 2.4.19 ¤è¤êÁ°¤Ç¤Ï¡¢¤³¤Î¾õ¶·¤Ç¥¨¥é¡¼
.B EFAULT
¤¬´Ö°ã¤Ã¤ÆÀ¸À®¤µ¤ì¤Æ¤¤¤¿)¡£
.\"O .SH "CONFORMING TO"
.SH ½àµò
SVr4, POSIX.1-2001.
.\"O .\" SVr4 defines an additional error
.\"O .\" code EAGAIN. The SVr4 error conditions don't map neatly onto Linux's.
.\"O POSIX says that the behavior of
.\"O .BR mprotect ()
.\"O is unspecified if it is applied to a region of memory that
.\"O was not obtained via
.\"O .BR mmap (2).
.\" SVr4 ¤Ç¤Ï¾¤Ë¥¨¥é¡¼¥³¡¼¥É EAGAIN ¤¬ÄêµÁ¤µ¤ì¤Æ¤¤¤ë¡£
.\" SVr4 ¤Î¥¨¥é¡¼¾ò·ï¤Ï Linux ¤Î¤â¤Î¤Ë¤­¤Á¤ó¤ÈÂбþ¤·¤Ê¤¤¡£
POSIX ¤Ç¤Ï¡¢
.BR mmap (2)
·Ðͳ¤Ç³ÍÆÀ¤·¤Æ¤¤¤Ê¤¤¥á¥â¥êÎΰè¤ËÂФ·¤Æ
.BR mprotect ()
¤ò¹Ô¤Ã¤¿¾ì¹ç¤Î
.BR mprotect ()
¤ÎÆ°ºî¤Ï̤ÄêµÁ¤Ç¤¢¤ë¤È¤µ¤ì¤Æ¤¤¤ë¡£
.\"O .SH NOTES
.SH Ãí°Õ
.\"O On Linux it is always permissible to call
.\"O .BR mprotect ()
.\"O on any address in a process's address space (except for the
.\"O kernel vsyscall area).
.\"O In particular it can be used
.\"O to change existing code mappings to be writable.
Linux ¤Ç¤Ï¡¢(¥«¡¼¥Í¥ë vsyscall Îΰè°Ê³°¤Î)
Ǥ°Õ¤Î¥×¥í¥»¥¹¥¢¥É¥ì¥¹¶õ´Ö¤ËÂФ·¤Æ
.BR mprotect ()
¤ò¸Æ¤Ó½Ð¤¹¤³¤È¤¬¡¢¾ï¤Ëµö¤µ¤ì¤Æ¤¤¤ë¡£
¤³¤ì¤ÏÆä˴û¸¤Î¥³¡¼¥É¥Þ¥Ã¥Ô¥ó¥°¤ò½ñ¤­¹þ¤ß²Äǽ¤Ë¤¹¤ë¤¿¤á¤Ë»È¤ï¤ì¤ë¡£

.\"O Whether
.\"O .B PROT_EXEC
.\"O has any effect different from
.\"O .B PROT_READ
.\"O is architecture- and kernel version-dependent.
.\"O On some hardware architectures (e.g., i386),
.\"O .B PROT_WRITE
.\"O implies
.\"O .BR PROT_READ .
.B PROT_EXEC
¤¬
.B PROT_READ
¤È°Û¤Ê¤ë±Æ¶Á¤ò»ý¤Ä¤«Èݤ«¤Ï¡¢¥¢¡¼¥­¥Æ¥¯¥Á¥ã¤È¥«¡¼¥Í¥ë¤Î¥Ð¡¼¥¸¥ç¥ó¤Ë°Í¸¤¹¤ë¡£
(i386 ¤Ê¤É¤Î) ¤¤¤¯¤Ä¤«¤Î¥¢¡¼¥­¥Æ¥¯¥Á¥ã¤Ç¤Ï¡¢
.B PROT_WRITE
¤ò¥»¥Ã¥È¤¹¤ë¤È¡¢°ÅÌۤΤ¦¤Á¤Ë
.B PROT_READ
¤¬¥»¥Ã¥È¤µ¤ì¤ë¡£

.\"O POSIX.1-2001 says that an implementation may permit access
.\"O other than that specified in
.\"O .IR prot ,
.\"O but at a minimum can only allow write access if
.\"O .B PROT_WRITE
.\"O has been set, and must not allow any access if
.\"O .B PROT_NONE
.\"O has been set.
POSIX.1-2001 ¤Ç¤Ï¡¢
.I prot
¤Ç»ØÄꤵ¤ì¤Æ¤¤¤Ê¤¤¥¢¥¯¥»¥¹¤òµö²Ä¤¹¤ë¼ÂÁõ¤òǧ¤á¤Æ¤¤¤ë¡£
¤¿¤À¤·¡¢ºÇÄã¸Â¡¢
.B PROT_WRITE
¤¬¥»¥Ã¥È¤µ¤ì¤Æ¤¤¤ë¾ì¹ç¤Ë¤Î¤ß½ñ¤­¹þ¤ß¥¢¥¯¥»¥¹¤¬µö²Ä¤µ¤ì¡¢
.B PROT_NONE
¤¬¥»¥Ã¥È¤µ¤ì¤Æ¤¤¤ë¾ì¹ç¤Ë¤Ï¥¢¥¯¥»¥¹¤Ïµö²Ä¤µ¤ì¤Ê¤¤ÅÀ¤À¤±¤Ï
Ëþ¤¿¤¹É¬Íפ¬¤¢¤ë¡£
.\"O .SH EXAMPLE
.SH Îã
.\" sigaction.2 refers to this example
.PP
.\"O The program below allocates four pages of memory, makes the third
.\"O of these pages read-only, and then executes a loop that walks upward
.\"O through the allocated region modifying bytes.
°Ê²¼¤Î¥×¥í¥°¥é¥à¤Ï¡¢¥á¥â¥ê¥Ú¡¼¥¸¤ò 4¤Ä³ÎÊݤ·¡¢¤½¤Î¤¦¤Á 3ÈÖÌܤΥڡ¼¥¸¤ò
Æɤ߹þ¤ßÀìÍѤËÀßÄꤹ¤ë¡£¤½¤Î¸å¤Ç¡¢³ÎÊݤ·¤¿Îΰè¤Î¥¢¥É¥ì¥¹¤Î¾®¤µ¤¤Êý¤«¤é
Â礭¤ÊÊý¤Ë¸þ¤«¤Ã¤Æ½çÈ֤˥Х¤¥ÈÃͤòÊѹ¹¤¹¤ë¥ë¡¼¥×¤ò¼Â¹Ô¤¹¤ë¡£

.\"O An example of what we might see when running the program is the
.\"O following:
¥×¥í¥°¥é¥à¤ò¼Â¹Ô¤·¤¿¾ì¹ç¤Î°ìÎã¤ò°Ê²¼¤Ë¼¨¤¹¡£

.in +4n
.nf
.RB "$" " ./a.out"
Start of region:        0x804c000
Got SIGSEGV at address: 0x804e000
.fi
.\"O .SS Program source
.SS ¥×¥í¥°¥é¥à¤Î¥½¡¼¥¹
\&
.in
.nf
#include <unistd.h>
#include <signal.h>
#include <stdio.h>
#include <malloc.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/mman.h>

#define handle_error(msg) \\
    do { perror(msg); exit(EXIT_FAILURE); } while (0)

char *buffer;

static void
handler(int sig, siginfo_t *si, void *unused)
{
    printf("Got SIGSEGV at address: 0x%lx\\n",
            (long) si\->si_addr);
    exit(EXIT_FAILURE);
}

int
main(void)
{
    char *p;
    int pagesize;
    struct sigaction sa;

    sa.sa_flags = SA_SIGINFO;
    sigemptyset(&sa.sa_mask);
    sa.sa_sigaction = handler;
    if (sigaction(SIGSEGV, &sa, NULL) == \-1)
        handle_error("sigaction");

    pagesize = sysconf(_SC_PAGE_SIZE);
    if (pagesize == \-1)
        handle_error("sysconf");

    /* Allocate a buffer aligned on a page boundary;
       initial protection is PROT_READ | PROT_WRITE */

    buffer = memalign(pagesize, 4 * pagesize);
    if (buffer == NULL)
        handle_error("memalign");

    printf("Start of region:        0x%lx\\n", (long) buffer);

    if (mprotect(buffer + pagesize * 2, pagesize,
                PROT_READ) == \-1)
        handle_error("mprotect");

    for (p = buffer ; ; )
        *(p++) = \(aqa\(aq;

    printf("Loop completed\\n");     /* Should never happen */
    exit(EXIT_SUCCESS);
}
.fi
.\"O .SH "SEE ALSO"
.SH ´ØÏ¢¹àÌÜ
.BR mmap (2),
.BR sysconf (3)