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/*
* SPDX-FileCopyrightText: 2011 , Peter Vrabec <pvrabec@redhat.com>
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <config.h>
#ifdef WITH_SELINUX
#include <stdio.h>
#include "defines.h"
#include <selinux/selinux.h>
#include <selinux/label.h>
#include "prototypes.h"
#include "shadowlog_internal.h"
static bool selinux_checked = false;
static bool selinux_enabled;
static /*@null@*/struct selabel_handle *selabel_hnd = NULL;
static void cleanup(void)
{
if (selabel_hnd) {
selabel_close(selabel_hnd);
selabel_hnd = NULL;
}
}
void reset_selinux_handle (void)
{
cleanup();
}
/*
* set_selinux_file_context - Set the security context before any file or
* directory creation.
*
* set_selinux_file_context () should be called before any creation
* of file, symlink, directory, ...
*
* Callers may have to Reset SELinux to create files with default
* contexts with reset_selinux_file_context
*/
int set_selinux_file_context (const char *dst_name, mode_t mode)
{
if (!selinux_checked) {
selinux_enabled = is_selinux_enabled () > 0;
selinux_checked = true;
}
if (selinux_enabled) {
/* Get the default security context for this file */
/*@null@*/char *fcontext_raw = NULL;
int r;
if (selabel_hnd == NULL) {
selabel_hnd = selabel_open(SELABEL_CTX_FILE, NULL, 0);
if (selabel_hnd == NULL) {
return security_getenforce () != 0;
}
(void) atexit(cleanup);
}
r = selabel_lookup_raw(selabel_hnd, &fcontext_raw, dst_name, mode);
if (r < 0) {
/* No context specified for the searched path */
if (errno == ENOENT) {
return 0;
}
return security_getenforce () != 0;
}
/* Set the security context for the next created file */
r = setfscreatecon_raw (fcontext_raw);
freecon (fcontext_raw);
if (r < 0) {
return security_getenforce () != 0;
}
}
return 0;
}
/*
* reset_selinux_file_context - Reset the security context to the default
* policy behavior
*
* reset_selinux_file_context () should be called after the context
* was changed with set_selinux_file_context ()
*/
int reset_selinux_file_context (void)
{
if (!selinux_checked) {
selinux_enabled = is_selinux_enabled () > 0;
selinux_checked = true;
}
if (selinux_enabled) {
if (setfscreatecon_raw (NULL) != 0) {
return security_getenforce () != 0;
}
}
return 0;
}
/*
* Log callback for libselinux internal error reporting.
*/
format_attr(printf, 2, 3)
static int selinux_log_cb (int type, const char *fmt, ...) {
va_list ap;
char *buf;
int r;
#ifdef WITH_AUDIT
static int selinux_audit_fd = -2;
#endif
va_start (ap, fmt);
r = vasprintf (&buf, fmt, ap);
va_end (ap);
if (r < 0) {
return 0;
}
#ifdef WITH_AUDIT
if (-2 == selinux_audit_fd) {
selinux_audit_fd = audit_open ();
if (-1 == selinux_audit_fd) {
/* You get these only when the kernel doesn't have
* audit compiled in. */
if ( (errno != EINVAL)
&& (errno != EPROTONOSUPPORT)
&& (errno != EAFNOSUPPORT)) {
(void) fputs (_("Cannot open audit interface.\n"),
shadow_logfd);
SYSLOG ((LOG_WARN, "Cannot open audit interface."));
}
}
}
if (-1 != selinux_audit_fd) {
if (SELINUX_AVC == type) {
if (audit_log_user_avc_message (selinux_audit_fd,
AUDIT_USER_AVC, buf, NULL, NULL,
NULL, 0) > 0) {
goto skip_syslog;
}
} else if (SELINUX_ERROR == type) {
if (audit_log_user_avc_message (selinux_audit_fd,
AUDIT_USER_SELINUX_ERR, buf, NULL, NULL,
NULL, 0) > 0) {
goto skip_syslog;
}
}
}
#endif
SYSLOG ((LOG_WARN, "libselinux: %s", buf));
skip_syslog:
free (buf);
return 0;
}
/*
* check_selinux_permit - Check whether SELinux grants the given
* operation
*
* Parameter is the SELinux permission name, e.g. rootok
*
* Returns 0 when permission is granted
* or something failed but running in
* permissive mode
*/
int check_selinux_permit (const char *perm_name)
{
char *user_context_raw;
int r;
if (0 == is_selinux_enabled ()) {
return 0;
}
selinux_set_callback (SELINUX_CB_LOG, (union selinux_callback) selinux_log_cb);
if (getprevcon_raw (&user_context_raw) != 0) {
fprintf (shadow_logfd,
_("%s: can not get previous SELinux process context: %s\n"),
shadow_progname, strerror (errno));
SYSLOG ((LOG_WARN,
"can not get previous SELinux process context: %s",
strerror (errno)));
return (security_getenforce () != 0);
}
r = selinux_check_access (user_context_raw, user_context_raw, "passwd", perm_name, NULL);
freecon (user_context_raw);
return r;
}
#else /* !WITH_SELINUX */
extern int errno; /* warning: ANSI C forbids an empty source file */
#endif /* !WITH_SELINUX */
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