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* Implemented backend daemon drop privileges after initialization to

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run as non-privileged user
This commit is contained in:
Olof hagsand 2019-09-14 18:34:32 +02:00
parent cacba627b5
commit 27fd99e7cd
61 changed files with 673 additions and 207 deletions
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lib/src/clixon_uid.c Normal file
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/*
*
***** BEGIN LICENSE BLOCK *****
Copyright (C) 2009-2019 Olof Hagsand and Benny Holmgren
This file is part of CLIXON.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
Alternatively, the contents of this file may be used under the terms of
the GNU General Public License Version 3 or later (the "GPL"),
in which case the provisions of the GPL are applicable instead
of those above. If you wish to allow use of your version of this file only
under the terms of the GPL, and not to allow others to
use your version of this file under the terms of Apache License version 2,
indicate your decision by deleting the provisions above and replace them with
the notice and other provisions required by the GPL. If you do not delete
the provisions above, a recipient may use your version of this file under
the terms of any one of the Apache License version 2 or the GPL.
***** END LICENSE BLOCK *****
* uid, gid, privileges
*/
#ifdef HAVE_CONFIG_H
#include "clixon_config.h" /* generated by config & autoconf */
#endif
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define __USE_GNU /* For setresuid */
#include <unistd.h>
#undef __USE_GNU
#include <stdarg.h>
#include <signal.h>
#include <syslog.h>
#include <errno.h>
#include <grp.h>
#include <pwd.h>
/* clicon */
#include "clixon_err.h"
#include "clixon_log.h"
#include "clixon_uid.h"
/*! Translate group name to gid. Return -1 if error or not found.
* @param[in] name Name of group
* @param[out] gid Group id
* @retval 0 OK
* @retval -1 Error. or not found
*/
int
group_name2gid(const char *name,
gid_t *gid)
{
int retval = -1;
char buf[1024];
struct group g0;
struct group *gr = &g0;
struct group *gtmp;
gr = &g0;
/* This leaks memory in ubuntu */
if (getgrnam_r(name, gr, buf, sizeof(buf), &gtmp) < 0){
clicon_err(OE_UNIX, errno, "getgrnam_r(%s)", name);
goto done;
}
if (gtmp == NULL){
clicon_err(OE_UNIX, 0, "No such group: %s", name);
goto done;
}
if (gid)
*gid = gr->gr_gid;
retval = 0;
done:
return retval;
}
/*! Translate user name to uid. Return -1 if error or not found.
* @param[in] name Name of user
* @param[out] uid User id
* @retval 0 OK
* @retval -1 Error. or not found
*/
int
name2uid(const char *name,
uid_t *uid)
{
int retval = -1;
char buf[1024];
struct passwd pwbuf;
struct passwd *pwbufp = NULL;
if (getpwnam_r(name, &pwbuf, buf, sizeof(buf), &pwbufp) != 0){
clicon_err(OE_UNIX, errno, "getpwnam_r(%s)", name);
goto done;
}
if (pwbufp == NULL){
clicon_err(OE_UNIX, 0, "No such user: %s", name);
goto done;
}
if (uid)
*uid = pwbufp->pw_uid;
retval = 0;
done:
return retval;
}
/* Privileges drop perm, temp and restore
* @see https://www.usenix.org/legacy/events/sec02/full_papers/chen/chen.pdf
*/
/*! Temporarily drop privileges
* @param[in] new_uid
*/
int
drop_priv_temp(uid_t new_uid)
{
int retval = -1;
if (setresuid(-1, new_uid, geteuid()) < 0){
clicon_err(OE_UNIX, errno, "setresuid");
goto done;
}
if (geteuid() != new_uid){
clicon_err(OE_UNIX, errno, "geteuid");
goto done;
}
retval = 0;
done:
return retval;
}
/*! Permanently drop privileges
* @param[in] new_uid
*/
int
drop_priv_perm(uid_t new_uid)
{
int retval = -1;
uid_t ruid;
uid_t euid;
uid_t suid;
if (setresuid(new_uid, new_uid, new_uid) < 0){
clicon_err(OE_UNIX, errno, "setresuid");
goto done;
}
if (getresuid(&ruid, &euid, &suid) < 0){
clicon_err(OE_UNIX, errno, "getresuid");
goto done;
}
if (ruid != new_uid ||
euid != new_uid ||
suid != new_uid){
clicon_err(OE_UNIX, EINVAL, "Non-matching uid");
goto done;
}
retval = 0;
done:
return retval;
}
/*! Restore privileges to saved level */
int
restore_priv(void)
{
int retval = -1;
uid_t ruid;
uid_t euid;
uid_t suid;
if (getresuid(&ruid, &euid, &suid) < 0){
clicon_err(OE_UNIX, errno, "setresuid");
goto done;
}
if (setresuid(-1, suid, -1) < 0){
clicon_err(OE_UNIX, errno, "setresuid");
goto done;
}
if (geteuid() != suid){
clicon_err(OE_UNIX, EINVAL, "Non-matching uid");
goto done;
}
retval = 0;
done:
return retval;
}