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/*
Unix SMB/CIFS implementation.
gain/lose root privileges
Copyright (C) Andrew Tridgell 2004
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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include "replace.h"
#include <talloc.h>
#include "lib/util/fault.h"
#include "system/passwd.h"
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include "../lib/util/unix_privs.h"
#include "../lib/util/setid.h"
/**
* @file
* @brief Gaining/losing root privileges
*/
/*
there are times when smbd needs to temporarily gain root privileges
to do some operation. To do this you call root_privileges(), which
returns a talloc handle. To restore your previous privileges
talloc_free() this pointer.
Note that this call is considered successful even if it does not
manage to gain root privileges, but it will call smb_abort() if it
fails to restore the privileges afterwards. The logic is that
failing to gain root access can be caught by whatever operation
needs to be run as root failing, but failing to lose the root
privileges is dangerous.
This also means that this code is safe to be called from completely
unprivileged processes.
*/
struct saved_state {
uid_t uid;
};
static int privileges_destructor(struct saved_state *s)
{
if (geteuid() != s->uid &&
samba_seteuid(s->uid) != 0) {
smb_panic("Failed to restore privileges");
}
return 0;
}
/**
* Obtain root privileges for the current process.
*
* The privileges can be dropped by talloc_free()-ing the
* token returned by this function
*/
void *root_privileges(void)
{
struct saved_state *s;
s = talloc(NULL, struct saved_state);
if (!s) return NULL;
s->uid = geteuid();
if (s->uid != 0) {
samba_seteuid(0);
}
talloc_set_destructor(s, privileges_destructor);
return s;
}
uid_t root_privileges_original_uid(void *s)
{
struct saved_state *saved = talloc_get_type_abort(s, struct saved_state);
return saved->uid;
}
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