88 lines
2.4 KiB
C
88 lines
2.4 KiB
C
/*
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* Author: Tatu Ylonen <ylo@cs.hut.fi>
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* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
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* All rights reserved
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* Created: Sat Sep 9 01:56:14 1995 ylo
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* Code for uid-swapping.
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*/
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#include "includes.h"
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RCSID("$Id: uidswap.c,v 1.5 1999/11/24 19:53:54 markus Exp $");
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#include "ssh.h"
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#include "uidswap.h"
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/*
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* Note: all these functions must work in all of the following cases:
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* 1. euid=0, ruid=0
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* 2. euid=0, ruid!=0
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* 3. euid!=0, ruid!=0
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* Additionally, they must work regardless of whether the system has
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* POSIX saved uids or not.
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*/
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#ifdef _POSIX_SAVED_IDS
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/* Lets assume that posix saved ids also work with seteuid, even though that
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is not part of the posix specification. */
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#define SAVED_IDS_WORK_WITH_SETEUID
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#endif /* _POSIX_SAVED_IDS */
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/* Saved effective uid. */
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static uid_t saved_euid = 0;
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/*
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* Temporarily changes to the given uid. If the effective user
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* id is not root, this does nothing. This call cannot be nested.
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*/
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void
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temporarily_use_uid(uid_t uid)
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{
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#ifdef SAVED_IDS_WORK_WITH_SETEUID
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/* Save the current euid. */
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saved_euid = geteuid();
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/* Set the effective uid to the given (unprivileged) uid. */
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if (seteuid(uid) == -1)
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debug("seteuid %d: %.100s", (int) uid, strerror(errno));
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#else /* SAVED_IDS_WORK_WITH_SETUID */
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/* Propagate the privileged uid to all of our uids. */
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if (setuid(geteuid()) < 0)
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debug("setuid %d: %.100s", (int) geteuid(), strerror(errno));
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/* Set the effective uid to the given (unprivileged) uid. */
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if (seteuid(uid) == -1)
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debug("seteuid %d: %.100s", (int) uid, strerror(errno));
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#endif /* SAVED_IDS_WORK_WITH_SETEUID */
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}
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/*
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* Restores to the original uid.
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*/
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void
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restore_uid()
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{
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#ifdef SAVED_IDS_WORK_WITH_SETEUID
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/* Set the effective uid back to the saved uid. */
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if (seteuid(saved_euid) < 0)
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debug("seteuid %d: %.100s", (int) saved_euid, strerror(errno));
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#else /* SAVED_IDS_WORK_WITH_SETEUID */
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/*
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* We are unable to restore the real uid to its unprivileged value.
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* Propagate the real uid (usually more privileged) to effective uid
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* as well.
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*/
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setuid(getuid());
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#endif /* SAVED_IDS_WORK_WITH_SETEUID */
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}
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/*
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* Permanently sets all uids to the given uid. This cannot be
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* called while temporarily_use_uid is effective.
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*/
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void
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permanently_set_uid(uid_t uid)
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{
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if (setuid(uid) < 0)
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debug("setuid %d: %.100s", (int) uid, strerror(errno));
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}
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