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/*
* Part of Very Secure FTPd
* Licence: GPL v2
* Author: Chris Evans
* secutil.c
*/
#include "secutil.h"
#include "str.h"
#include "sysutil.h"
#include "sysstr.h"
#include "utility.h"
#include "sysdeputil.h"
void
vsf_secutil_change_credentials(const struct mystr* p_user_str,
const struct mystr* p_dir_str,
const struct mystr* p_ext_dir_str,
unsigned int caps, unsigned int options)
{
struct vsf_sysutil_user* p_user;
if (!vsf_sysutil_running_as_root())
{
bug("vsf_secutil_change_credentials: not running as root");
}
p_user = str_getpwnam(p_user_str);
if (p_user == 0)
{
die2("cannot locate user entry:", str_getbuf(p_user_str));
}
{
struct mystr dir_str = INIT_MYSTR;
/* Work out where the chroot() jail is */
if (p_dir_str == 0 || str_isempty(p_dir_str))
{
str_alloc_text(&dir_str, vsf_sysutil_user_get_homedir(p_user));
}
else
{
str_copy(&dir_str, p_dir_str);
}
/* Sort out supplementary groups before the chroot(). We need to access
* /etc/groups
*/
if (options & VSF_SECUTIL_OPTION_USE_GROUPS)
{
vsf_sysutil_initgroups(p_user);
}
else
{
vsf_sysutil_clear_supp_groups();
}
/* Always do the chdir() regardless of whether we are chroot()'ing */
{
/* Do chdir() with the target effective IDs to cater for NFS mounted
* home directories.
*/
int saved_euid = 0;
int saved_egid = 0;
int retval;
if (options & VSF_SECUTIL_OPTION_CHANGE_EUID)
{
saved_euid = vsf_sysutil_geteuid();
saved_egid = vsf_sysutil_getegid();
vsf_sysutil_setegid(p_user);
vsf_sysutil_seteuid(p_user);
}
retval = str_chdir(&dir_str);
if (retval != 0)
{
die2("cannot change directory:", str_getbuf(&dir_str));
}
if (p_ext_dir_str && !str_isempty(p_ext_dir_str))
{
retval = str_chdir(p_ext_dir_str);
/* Failure on the extra directory is OK as long as we're not in
* chroot() mode
*/
if (retval != 0 && !(options & VSF_SECUTIL_OPTION_CHROOT))
{
retval = 0;
}
}
if (retval != 0)
{
die2("cannot change directory:", str_getbuf(p_ext_dir_str));
}
if (options & VSF_SECUTIL_OPTION_CHANGE_EUID)
{
vsf_sysutil_seteuid_numeric(saved_euid);
vsf_sysutil_setegid_numeric(saved_egid);
}
/* Do the chroot() if required */
if (options & VSF_SECUTIL_OPTION_CHROOT)
{
vsf_sysutil_chroot(".");
}
}
str_free(&dir_str);
}
if (options & VSF_SECUTIL_OPTION_NO_FDS)
{
vsf_sysutil_set_no_fds();
}
/* Handle capabilities */
if (caps)
{
if (!vsf_sysdep_has_capabilities())
{
/* Need privilege but OS has no capabilities - have to keep root */
return;
}
if (!vsf_sysdep_has_capabilities_as_non_root())
{
vsf_sysdep_adopt_capabilities(caps);
return;
}
vsf_sysdep_keep_capabilities();
}
/* Set group id */
vsf_sysutil_setgid(p_user);
/* Finally set user id */
vsf_sysutil_setuid(p_user);
if (caps)
{
vsf_sysdep_adopt_capabilities(caps);
}
if (options & VSF_SECUTIL_OPTION_NO_PROCS)
{
vsf_sysutil_set_no_procs();
}
/* Misconfiguration check: don't ever chroot() to a directory writable by
* the current user.
*/
if (options & VSF_SECUTIL_OPTION_CHROOT)
{
if (vsf_sysutil_write_access("/"))
{
die("vsftpd: refusing to run with writable root inside chroot()");
}
}
}
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