tools/regression/mlock/mlock.c

   1 /*-
   2  * Copyright (c) 2005 Robert N. M. Watson
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $FreeBSD$
  27  */
  28
  29 #include <sys/types.h>
  30 #include <sys/mman.h>
  31
  32 #include <err.h>
  33 #include <errno.h>
  34 #include <pwd.h>
  35 #include <stdlib.h>
  36 #include <string.h>
  37 #include <unistd.h>
  38
  39 #define NOBODY  "nobody"
  40
  41 /*
  42  * Simple exercise for the mlock() system call -- confirm that mlock() and
  43  * munlock() return success on an anonymously mapped memory page when running
  44  * with privilege; confirm that they fail with EPERM when running
  45  * unprivileged.
  46  */
  47 int
  48 main(int argc, char *argv[])
  49 {
  50         struct passwd *pwd;
  51         int pagesize;
  52         char *page;
  53
  54         if (geteuid() != 0)
  55                 errx(-1, "mlock must run as root");
  56
  57         errno = 0;
  58         pwd = getpwnam(NOBODY);
  59         if (pwd == NULL && errno == 0)
  60                 errx(-1, "getpwnam: user \"%s\" not found", NOBODY);
  61         if (pwd == NULL)
  62                 errx(-1, "getpwnam: %s", strerror(errno));
  63         if (pwd->pw_uid == 0)
  64                 errx(-1, "getpwnam: user \"%s\" has uid 0", NOBODY);
  65
  66         pagesize = getpagesize();
  67         page = mmap(NULL, pagesize, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0);
  68         if (page == MAP_FAILED)
  69                 errx(-1, "mmap: %s", strerror(errno));
  70
  71         if (mlock(page, pagesize) < 0)
  72                 errx(-1, "mlock privileged: %s", strerror(errno));
  73
  74         if (munlock(page, pagesize) < 0)
  75                 errx(-1, "munlock privileged: %s", strerror(errno));
  76
  77         if (seteuid(pwd->pw_uid) < 0)
  78                 errx(-1, "seteuid: %s", strerror(errno));
  79
  80         if (mlock(page, pagesize) == 0)
  81                 errx(-1, "mlock unprivileged: succeeded but shouldn't have");
  82         if (errno != EPERM)
  83                 errx(-1, "mlock unprivileged: %s", strerror(errno));
  84
  85         if (munlock(page, pagesize) == 0)
  86                 errx(-1, "munlock unprivileged: succeeded but shouldn't have");
  87         if (errno != EPERM)
  88                 errx(-1, "munlock unprivileged: %s", strerror(errno));
  89
  90         return (0);
  91 }