121 lines
2.7 KiB
C
121 lines
2.7 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Copyright (C) 2021 Microsoft Corporation
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*
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* Author: Lakshmi Ramasubramanian (nramas@linux.microsoft.com)
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*
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* Measure critical data structures maintained by SELinux
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* using IMA subsystem.
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*/
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#include <linux/vmalloc.h>
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#include <linux/ima.h>
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#include "security.h"
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#include "ima.h"
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/*
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* selinux_ima_collect_state - Read selinux configuration settings
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*
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* On success returns the configuration settings string.
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* On error, returns NULL.
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*/
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static char *selinux_ima_collect_state(void)
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{
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const char *on = "=1;", *off = "=0;";
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char *buf;
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int buf_len, len, i, rc;
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buf_len = strlen("initialized=0;enforcing=0;checkreqprot=0;") + 1;
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len = strlen(on);
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for (i = 0; i < __POLICYDB_CAP_MAX; i++)
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buf_len += strlen(selinux_policycap_names[i]) + len;
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buf = kzalloc(buf_len, GFP_KERNEL);
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if (!buf)
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return NULL;
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rc = strscpy(buf, "initialized", buf_len);
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WARN_ON(rc < 0);
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rc = strlcat(buf, selinux_initialized() ? on : off, buf_len);
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WARN_ON(rc >= buf_len);
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rc = strlcat(buf, "enforcing", buf_len);
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WARN_ON(rc >= buf_len);
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rc = strlcat(buf, enforcing_enabled() ? on : off, buf_len);
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WARN_ON(rc >= buf_len);
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rc = strlcat(buf, "checkreqprot", buf_len);
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WARN_ON(rc >= buf_len);
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rc = strlcat(buf, checkreqprot_get() ? on : off, buf_len);
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WARN_ON(rc >= buf_len);
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for (i = 0; i < __POLICYDB_CAP_MAX; i++) {
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rc = strlcat(buf, selinux_policycap_names[i], buf_len);
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WARN_ON(rc >= buf_len);
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rc = strlcat(buf, selinux_state.policycap[i] ? on : off,
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buf_len);
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WARN_ON(rc >= buf_len);
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}
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return buf;
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}
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/*
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* selinux_ima_measure_state_locked - Measure SELinux state and hash of policy
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*/
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void selinux_ima_measure_state_locked(void)
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{
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char *state_str = NULL;
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void *policy = NULL;
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size_t policy_len;
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int rc = 0;
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lockdep_assert_held(&selinux_state.policy_mutex);
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state_str = selinux_ima_collect_state();
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if (!state_str) {
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pr_err("SELinux: %s: failed to read state.\n", __func__);
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return;
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}
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ima_measure_critical_data("selinux", "selinux-state",
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state_str, strlen(state_str), false,
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NULL, 0);
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kfree(state_str);
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/*
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* Measure SELinux policy only after initialization is completed.
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*/
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if (!selinux_initialized())
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return;
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rc = security_read_state_kernel(&policy, &policy_len);
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if (rc) {
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pr_err("SELinux: %s: failed to read policy %d.\n", __func__, rc);
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return;
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}
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ima_measure_critical_data("selinux", "selinux-policy-hash",
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policy, policy_len, true,
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NULL, 0);
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vfree(policy);
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}
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/*
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* selinux_ima_measure_state - Measure SELinux state and hash of policy
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*/
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void selinux_ima_measure_state(void)
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{
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lockdep_assert_not_held(&selinux_state.policy_mutex);
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mutex_lock(&selinux_state.policy_mutex);
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selinux_ima_measure_state_locked();
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mutex_unlock(&selinux_state.policy_mutex);
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}
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