68d3acaccb
When you switch-root into a new root that has SELinux policy, you're
supposed to to run selinux_init_load_policy() to set up SELinux and load
policy. Normally this gets handled by selinux_setup().
But if SELinux was already initialized, selinux_setup() skips loading
policy and returns 0. So if you load policy normally, and then you
switch-root to a new root that has new policy, selinux_setup() never
loads the new policy. What gives?
As far as I can tell, this check is an artifact of how selinux_setup()
worked when it was first written (see commit c4dcdb9 / systemd v12):
* when systemd starts, run selinux_setup()
* if selinux_setup() loads policy OK, restart systemd
So the "if policy already loaded, skip load and return 0" check was
there to prevent an infinite re-exec loop.
Modern systemd only calls selinux_setup() on initial load and after
switch-root, and selinux_setup() no longer restarts systemd, so we don't
need that check to guard against the infinite loop anymore.
So: this patch removes the "return 0", thus allowing selinux_setup() to
actually perform SELinux setup after switch-root.
We still want to check to see if SELinux is initialized, because if
selinux_init_load_policy() fails *but* SELinux is initialized that means
we still have (old) policy active. So we don't need to halt if
enforce=1.
128 lines
3.8 KiB
C
128 lines
3.8 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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/***
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <unistd.h>
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#include <stdio.h>
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#include <errno.h>
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#include <string.h>
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#include <stdlib.h>
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#ifdef HAVE_SELINUX
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#include <selinux/selinux.h>
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#endif
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#include "selinux-setup.h"
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#include "selinux-util.h"
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#include "label.h"
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#include "mount-setup.h"
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#include "macro.h"
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#include "util.h"
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#include "log.h"
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#ifdef HAVE_SELINUX
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static int null_log(int type, const char *fmt, ...) {
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return 0;
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}
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#endif
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int selinux_setup(bool *loaded_policy) {
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#ifdef HAVE_SELINUX
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int enforce = 0;
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usec_t before_load, after_load;
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security_context_t con;
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int r;
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union selinux_callback cb;
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bool initialized = false;
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assert(loaded_policy);
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/* Turn off all of SELinux' own logging, we want to do that */
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cb.func_log = null_log;
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selinux_set_callback(SELINUX_CB_LOG, cb);
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/* Don't load policy in the initrd if we don't appear to have
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* it. For the real root, we check below if we've already
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* loaded policy, and return gracefully.
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*/
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if (in_initrd() && access(selinux_path(), F_OK) < 0)
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return 0;
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/* Already initialized by somebody else? */
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r = getcon_raw(&con);
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if (r == 0) {
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initialized = !streq(con, "kernel");
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freecon(con);
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}
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/* Make sure we have no fds open while loading the policy and
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* transitioning */
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log_close();
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/* Now load the policy */
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before_load = now(CLOCK_MONOTONIC);
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r = selinux_init_load_policy(&enforce);
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if (r == 0) {
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char timespan[FORMAT_TIMESPAN_MAX];
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char *label;
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retest_selinux();
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/* Transition to the new context */
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r = label_get_create_label_from_exe(SYSTEMD_BINARY_PATH, &label);
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if (r < 0 || label == NULL) {
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log_open();
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log_error("Failed to compute init label, ignoring.");
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} else {
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r = setcon(label);
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log_open();
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if (r < 0)
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log_error("Failed to transition into init label '%s', ignoring.", label);
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label_free(label);
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}
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after_load = now(CLOCK_MONOTONIC);
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log_info("Successfully loaded SELinux policy in %s.",
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format_timespan(timespan, sizeof(timespan), after_load - before_load, 0));
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*loaded_policy = true;
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} else {
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log_open();
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if (enforce > 0) {
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if (!initialized) {
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log_error("Failed to load SELinux policy. Freezing.");
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return -EIO;
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}
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log_warning("Failed to load new SELinux policy. Continuing with old policy.");
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} else
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log_debug("Unable to load SELinux policy. Ignoring.");
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}
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#endif
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return 0;
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}
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