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/*
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* Copyright (c) 2004, 2005 Darren Tucker (dtucker at zip com au).
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <sys/types.h>
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#include <errno.h>
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#include <unistd.h>
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int
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setresuid(uid_t ruid, uid_t euid, uid_t suid)
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{
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uid_t ouid;
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int ret = -1;
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/* Allow only the tested configuration. */
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if (ruid != euid || euid != suid) {
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errno = ENOSYS;
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return -1;
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}
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ouid = getuid();
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# if defined(HAVE_SETREUID) && !defined(BROKEN_SETREUID)
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if ((ret = setreuid(euid, euid)) == -1)
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return -1;
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# else
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# ifndef SETEUID_BREAKS_SETUID
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if (seteuid(euid) == -1)
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return -1;
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# endif
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if ((ret = setuid(ruid)) == -1)
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return -1;
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# endif
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/*
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* When real, effective and saved uids are the same and we have
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* changed uids, sanity check that we cannot restore the old uid.
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*/
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if (ruid == euid && euid == suid && ouid != ruid &&
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setuid(ouid) != -1 && seteuid(ouid) != -1) {
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errno = EINVAL;
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return -1;
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}
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/*
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* Finally, check that the real and effective uids are what we
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* expect.
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*/
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if (getuid() != ruid || geteuid() != euid) {
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errno = EACCES;
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return -1;
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}
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return ret;
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}
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