92 lines
2.7 KiB
C
92 lines
2.7 KiB
C
/*
|
|
* Author: Tatu Ylonen <ylo@cs.hut.fi>
|
|
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
|
|
* All rights reserved
|
|
* Code for uid-swapping.
|
|
*
|
|
* As far as I am concerned, the code I have written for this software
|
|
* can be used freely for any purpose. Any derived versions of this
|
|
* software must be clearly marked as such, and if the derived work is
|
|
* incompatible with the protocol description in the RFC file, it must be
|
|
* called by a name other than "ssh" or "Secure Shell".
|
|
*/
|
|
|
|
#include "includes.h"
|
|
RCSID("$OpenBSD: uidswap.c,v 1.13 2001/01/21 19:06:01 markus Exp $");
|
|
|
|
#include "log.h"
|
|
#include "uidswap.h"
|
|
|
|
/*
|
|
* Note: all these functions must work in all of the following cases:
|
|
* 1. euid=0, ruid=0
|
|
* 2. euid=0, ruid!=0
|
|
* 3. euid!=0, ruid!=0
|
|
* Additionally, they must work regardless of whether the system has
|
|
* POSIX saved uids or not.
|
|
*/
|
|
|
|
#ifdef _POSIX_SAVED_IDS
|
|
/* Lets assume that posix saved ids also work with seteuid, even though that
|
|
is not part of the posix specification. */
|
|
#define SAVED_IDS_WORK_WITH_SETEUID
|
|
/* Saved effective uid. */
|
|
static uid_t saved_euid = 0;
|
|
#endif /* _POSIX_SAVED_IDS */
|
|
|
|
/*
|
|
* Temporarily changes to the given uid. If the effective user
|
|
* id is not root, this does nothing. This call cannot be nested.
|
|
*/
|
|
void
|
|
temporarily_use_uid(uid_t uid)
|
|
{
|
|
#ifdef SAVED_IDS_WORK_WITH_SETEUID
|
|
/* Save the current euid. */
|
|
saved_euid = geteuid();
|
|
|
|
/* Set the effective uid to the given (unprivileged) uid. */
|
|
if (seteuid(uid) == -1)
|
|
debug("seteuid %u: %.100s", (u_int) uid, strerror(errno));
|
|
#else /* SAVED_IDS_WORK_WITH_SETEUID */
|
|
/* Propagate the privileged uid to all of our uids. */
|
|
if (setuid(geteuid()) < 0)
|
|
debug("setuid %u: %.100s", (u_int) geteuid(), strerror(errno));
|
|
|
|
/* Set the effective uid to the given (unprivileged) uid. */
|
|
if (seteuid(uid) == -1)
|
|
debug("seteuid %u: %.100s", (u_int) uid, strerror(errno));
|
|
#endif /* SAVED_IDS_WORK_WITH_SETEUID */
|
|
}
|
|
|
|
/*
|
|
* Restores to the original uid.
|
|
*/
|
|
void
|
|
restore_uid(void)
|
|
{
|
|
#ifdef SAVED_IDS_WORK_WITH_SETEUID
|
|
/* Set the effective uid back to the saved uid. */
|
|
if (seteuid(saved_euid) < 0)
|
|
debug("seteuid %u: %.100s", (u_int) saved_euid, strerror(errno));
|
|
#else /* SAVED_IDS_WORK_WITH_SETEUID */
|
|
/*
|
|
* We are unable to restore the real uid to its unprivileged value.
|
|
* Propagate the real uid (usually more privileged) to effective uid
|
|
* as well.
|
|
*/
|
|
setuid(getuid());
|
|
#endif /* SAVED_IDS_WORK_WITH_SETEUID */
|
|
}
|
|
|
|
/*
|
|
* Permanently sets all uids to the given uid. This cannot be
|
|
* called while temporarily_use_uid is effective.
|
|
*/
|
|
void
|
|
permanently_set_uid(uid_t uid)
|
|
{
|
|
if (setuid(uid) < 0)
|
|
debug("setuid %u: %.100s", (u_int) uid, strerror(errno));
|
|
}
|