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/*
Copyright (C) (2004 - 2006) (Venkata Ramana Enaganti) <ramana@intraperson.com>
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later
version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/*
For dropping root capabilities and to
keep only those that are required
all forked procs -- all backup procs will have only CAP_DAC_READ_SEARCH.
*/
#include <sys/capability.h>
#include "msg.h"
#include "dropcap.h"
#ifdef DISPLAY_CAP
static void dropcap_discap( void )
{
char *txt;
cap_t ct;
if( ! ( ct = cap_get_proc() ) )
{
msglog( MSG_ERR|LOG_ERRNO, "dropcap_discap: cap_get_proc" );
return;
}
if( ! ( txt = cap_to_text( ct, NULL ) ) )
{
msglog( MSG_ERR, "dropcap_discap: cap_to_text" );
cap_free( ct );
return;
}
msglog( MSG_INFO, "remaining capabilities: %s", txt );
cap_free( txt );
cap_free( ct );
}
#endif
void dropcap_drop( void )
{
cap_t ct;
const char *caps =
/* CAP_CHOWN
This overrides the restriction of changing file
ownership and group ownership.
*/
"cap_chown," \
/* CAP_DAC_OVERRIDE
Override all DAC access.
*/
"cap_dac_override," \
/* CAP_FOWNER
Overrides all restrictions about allowed operations
on files, where file owner ID must be equal to the user ID,
except where CAP_FSETID is applicable.
It doesn't override MAC and DAC restrictions.
*/
"cap_fowner," \
/* CAP_CHOWN
Overrides the following restrictions that the
effective user ID shall match the file owner ID
when setting the S_ISUID and S_ISGID bits on that
file; that the effective group ID (or one of
the supplementary group IDs) shall match the file
owner ID when setting the S_ISGID bit on that file
*/
"cap_fsetid," \
/* CAP_KILL
Overrides the restriction that the real or effective
user ID of a process sending a signal must match
the real or effective user ID of the process receiving the signal.
"cap_kill," \
*/
/* CAP_SYS_ADMIN -- too much power but
we are interested only in the following,
Allow mount() and umount()
Allow some autofs root ioctls
*/
"cap_sys_admin+ep" \
" " \
/* CAP_DAC_READ_SEARCH -- for backup;
Overrides all DAC restrictions regarding read and
search on files and directories.
*/
"cap_dac_read_search+epi";
if( ! ( ct = cap_from_text( caps ) ) )
msglog( MSG_FATAL|LOG_ERRNO, "dropcap_drop: cap_from_text" );
msglog( MSG_INFO, "giving up unnecessary root privileges" );
if( cap_set_proc( ct ) )
{
msglog( MSG_ERR|LOG_ERRNO, "dropcap_drop: cap_set_proc" );
msglog( MSG_WARNING, "could not drop root privileges" );
}
cap_free( ct );
#ifdef DISPLAY_CAP
/*enable this if you are too paranoid*/
dropcap_discap();
#endif
}
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