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90 lines
2.9 KiB
C
90 lines
2.9 KiB
C
/*-
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* Copyright (c) 2005 Robert N. M. Watson
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/types.h>
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#include <sys/mman.h>
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#include <err.h>
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#include <errno.h>
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#include <pwd.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#define NOBODY "nobody"
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/*
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* Simple exercise for the mlock() system call -- confirm that mlock() and
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* munlock() return success on an anonymously mapped memory page when running
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* with privilege; confirm that they fail with EPERM when running
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* unprivileged.
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*/
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int
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main(int argc, char *argv[])
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{
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struct passwd *pwd;
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int pagesize;
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char *page;
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if (geteuid() != 0)
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errx(-1, "mlock must run as root");
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errno = 0;
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pwd = getpwnam(NOBODY);
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if (pwd == NULL && errno == 0)
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errx(-1, "getpwnam: user \"%s\" not found", NOBODY);
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if (pwd == NULL)
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errx(-1, "getpwnam: %s", strerror(errno));
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if (pwd->pw_uid == 0)
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errx(-1, "getpwnam: user \"%s\" has uid 0", NOBODY);
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pagesize = getpagesize();
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page = mmap(NULL, pagesize, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0);
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if (page == MAP_FAILED)
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errx(-1, "mmap: %s", strerror(errno));
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if (mlock(page, pagesize) < 0)
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errx(-1, "mlock privileged: %s", strerror(errno));
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if (munlock(page, pagesize) < 0)
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errx(-1, "munlock privileged: %s", strerror(errno));
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if (seteuid(pwd->pw_uid) < 0)
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errx(-1, "seteuid: %s", strerror(errno));
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if (mlock(page, pagesize) == 0)
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errx(-1, "mlock unprivileged: succeeded but shouldn't have");
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if (errno != EPERM)
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errx(-1, "mlock unprivileged: %s", strerror(errno));
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if (munlock(page, pagesize) == 0)
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errx(-1, "munlock unprivileged: succeeded but shouldn't have");
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if (errno != EPERM)
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errx(-1, "munlock unprivileged: %s", strerror(errno));
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return (0);
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}
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