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sudo-project
GitHub Repository: sudo-project/sudo
 Path: blob/main/lib/iolog/iolog_swapids.c
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/*

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 * SPDX-License-Identifier: ISC

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 *

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 * Copyright (c) 2009-2021 Todd C. Miller <[email protected]>

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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 <config.h>

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#include <stdio.h>

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#include <stdlib.h>

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#ifdef HAVE_STDBOOL_H

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# include <stdbool.h>

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#else

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# include <compat/stdbool.h>

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#endif

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#include <time.h>

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#include <unistd.h>

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#include <sudo_compat.h>

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#include <sudo_debug.h>

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#include <sudo_fatal.h>

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#include <sudo_gettext.h>

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#include <sudo_iolog.h>

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/*

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 * Set effective user and group-IDs to iolog_uid and iolog_gid.

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 * If restore flag is set, swap them back.

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 */

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bool

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iolog_swapids(bool restore)

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{

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#ifdef HAVE_SETEUID

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    static uid_t user_euid = (uid_t)-1;

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    static gid_t user_egid = (gid_t)-1;

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    const uid_t iolog_uid = iolog_get_uid();

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    const gid_t iolog_gid = iolog_get_gid();

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    debug_decl(io_swapids, SUDO_DEBUG_UTIL);

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    if (user_euid == (uid_t)-1)

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	user_euid = geteuid();

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    if (user_egid == (gid_t)-1)

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	user_egid = getegid();

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    if (user_euid == iolog_uid && user_egid == iolog_gid) {

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	sudo_debug_printf(SUDO_DEBUG_NOTICE,

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	    "%s: effective uid/gid matches iolog uid/gid, nothing to do",

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	    __func__);

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	debug_return_bool(true);

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    }

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    if (restore) {

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	if (seteuid(user_euid) == -1) {

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	    sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,

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		"%s: unable to restore effective uid to %d", __func__,

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		(int)user_euid);

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	    sudo_warn("seteuid() %d -> %d", (int)iolog_uid, (int)user_euid);

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	    debug_return_bool(false);

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	}

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	if (setegid(user_egid) == -1) {

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	    sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,

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		"%s: unable to restore effective gid to %d", __func__,

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		(int)user_egid);

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	    sudo_warn("setegid() %d -> %d", (int)iolog_gid, (int)user_egid);

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	    debug_return_bool(false);

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	}

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    } else {

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	/* Fail silently if the user has insufficient privileges. */

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	if (setegid(iolog_gid) == -1) {

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	    sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,

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		"%s: unable to set effective gid to %d", __func__,

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		(int)iolog_gid);

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	    debug_return_bool(false);

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	}

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	if (seteuid(iolog_uid) == -1) {

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	    sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,

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		"%s: unable to set effective uid to %d", __func__,

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		(int)iolog_uid);

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	    debug_return_bool(false);

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	}

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    }

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    debug_return_bool(true);

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#else

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    return false;

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#endif

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}

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