summaryrefslogtreecommitdiff
path: root/security/integrity/ima/ima_main.c
diff options
context:
space:
mode:
authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /security/integrity/ima/ima_main.c
Initial import
Diffstat (limited to 'security/integrity/ima/ima_main.c')
-rw-r--r--security/integrity/ima/ima_main.c361
1 files changed, 361 insertions, 0 deletions
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
new file mode 100644
index 000000000..eeee00dce
--- /dev/null
+++ b/security/integrity/ima/ima_main.c
@@ -0,0 +1,361 @@
+/*
+ * Copyright (C) 2005,2006,2007,2008 IBM Corporation
+ *
+ * Authors:
+ * Reiner Sailer <sailer@watson.ibm.com>
+ * Serge Hallyn <serue@us.ibm.com>
+ * Kylene Hall <kylene@us.ibm.com>
+ * Mimi Zohar <zohar@us.ibm.com>
+ *
+ * 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, version 2 of the
+ * License.
+ *
+ * File: ima_main.c
+ * implements the IMA hooks: ima_bprm_check, ima_file_mmap,
+ * and ima_file_check.
+ */
+#include <linux/module.h>
+#include <linux/file.h>
+#include <linux/binfmts.h>
+#include <linux/mount.h>
+#include <linux/mman.h>
+#include <linux/slab.h>
+#include <linux/xattr.h>
+#include <linux/ima.h>
+#include <crypto/hash_info.h>
+
+#include "ima.h"
+
+int ima_initialized;
+
+#ifdef CONFIG_IMA_APPRAISE
+int ima_appraise = IMA_APPRAISE_ENFORCE;
+#else
+int ima_appraise;
+#endif
+
+int ima_hash_algo = HASH_ALGO_SHA1;
+static int hash_setup_done;
+
+static int __init hash_setup(char *str)
+{
+ struct ima_template_desc *template_desc = ima_template_desc_current();
+ int i;
+
+ if (hash_setup_done)
+ return 1;
+
+ if (strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) == 0) {
+ if (strncmp(str, "sha1", 4) == 0)
+ ima_hash_algo = HASH_ALGO_SHA1;
+ else if (strncmp(str, "md5", 3) == 0)
+ ima_hash_algo = HASH_ALGO_MD5;
+ goto out;
+ }
+
+ for (i = 0; i < HASH_ALGO__LAST; i++) {
+ if (strcmp(str, hash_algo_name[i]) == 0) {
+ ima_hash_algo = i;
+ break;
+ }
+ }
+out:
+ hash_setup_done = 1;
+ return 1;
+}
+__setup("ima_hash=", hash_setup);
+
+/*
+ * ima_rdwr_violation_check
+ *
+ * Only invalidate the PCR for measured files:
+ * - Opening a file for write when already open for read,
+ * results in a time of measure, time of use (ToMToU) error.
+ * - Opening a file for read when already open for write,
+ * could result in a file measurement error.
+ *
+ */
+static void ima_rdwr_violation_check(struct file *file,
+ struct integrity_iint_cache *iint,
+ int must_measure,
+ char **pathbuf,
+ const char **pathname)
+{
+ struct inode *inode = file_inode(file);
+ fmode_t mode = file->f_mode;
+ bool send_tomtou = false, send_writers = false;
+
+ if (mode & FMODE_WRITE) {
+ if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) {
+ if (!iint)
+ iint = integrity_iint_find(inode);
+ /* IMA_MEASURE is set from reader side */
+ if (iint && (iint->flags & IMA_MEASURE))
+ send_tomtou = true;
+ }
+ } else {
+ if ((atomic_read(&inode->i_writecount) > 0) && must_measure)
+ send_writers = true;
+ }
+
+ if (!send_tomtou && !send_writers)
+ return;
+
+ *pathname = ima_d_path(&file->f_path, pathbuf);
+
+ if (send_tomtou)
+ ima_add_violation(file, *pathname, "invalid_pcr", "ToMToU");
+ if (send_writers)
+ ima_add_violation(file, *pathname,
+ "invalid_pcr", "open_writers");
+}
+
+static void ima_check_last_writer(struct integrity_iint_cache *iint,
+ struct inode *inode, struct file *file)
+{
+ fmode_t mode = file->f_mode;
+
+ if (!(mode & FMODE_WRITE))
+ return;
+
+ mutex_lock(&inode->i_mutex);
+ if (atomic_read(&inode->i_writecount) == 1) {
+ if ((iint->version != inode->i_version) ||
+ (iint->flags & IMA_NEW_FILE)) {
+ iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE);
+ if (iint->flags & IMA_APPRAISE)
+ ima_update_xattr(iint, file);
+ }
+ }
+ mutex_unlock(&inode->i_mutex);
+}
+
+/**
+ * ima_file_free - called on __fput()
+ * @file: pointer to file structure being freed
+ *
+ * Flag files that changed, based on i_version
+ */
+void ima_file_free(struct file *file)
+{
+ struct inode *inode = file_inode(file);
+ struct integrity_iint_cache *iint;
+
+ if (!ima_policy_flag || !S_ISREG(inode->i_mode))
+ return;
+
+ iint = integrity_iint_find(inode);
+ if (!iint)
+ return;
+
+ ima_check_last_writer(iint, inode, file);
+}
+
+static int process_measurement(struct file *file, int mask, int function,
+ int opened)
+{
+ struct inode *inode = file_inode(file);
+ struct integrity_iint_cache *iint = NULL;
+ struct ima_template_desc *template_desc;
+ char *pathbuf = NULL;
+ const char *pathname = NULL;
+ int rc = -ENOMEM, action, must_appraise;
+ struct evm_ima_xattr_data *xattr_value = NULL, **xattr_ptr = NULL;
+ int xattr_len = 0;
+ bool violation_check;
+
+ if (!ima_policy_flag || !S_ISREG(inode->i_mode))
+ return 0;
+
+ /* Return an IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT action
+ * bitmask based on the appraise/audit/measurement policy.
+ * Included is the appraise submask.
+ */
+ action = ima_get_action(inode, mask, function);
+ violation_check = ((function == FILE_CHECK || function == MMAP_CHECK) &&
+ (ima_policy_flag & IMA_MEASURE));
+ if (!action && !violation_check)
+ return 0;
+
+ must_appraise = action & IMA_APPRAISE;
+
+ /* Is the appraise rule hook specific? */
+ if (action & IMA_FILE_APPRAISE)
+ function = FILE_CHECK;
+
+ mutex_lock(&inode->i_mutex);
+
+ if (action) {
+ iint = integrity_inode_get(inode);
+ if (!iint)
+ goto out;
+ }
+
+ if (violation_check) {
+ ima_rdwr_violation_check(file, iint, action & IMA_MEASURE,
+ &pathbuf, &pathname);
+ if (!action) {
+ rc = 0;
+ goto out_free;
+ }
+ }
+
+ /* Determine if already appraised/measured based on bitmask
+ * (IMA_MEASURE, IMA_MEASURED, IMA_XXXX_APPRAISE, IMA_XXXX_APPRAISED,
+ * IMA_AUDIT, IMA_AUDITED)
+ */
+ iint->flags |= action;
+ action &= IMA_DO_MASK;
+ action &= ~((iint->flags & IMA_DONE_MASK) >> 1);
+
+ /* Nothing to do, just return existing appraised status */
+ if (!action) {
+ if (must_appraise)
+ rc = ima_get_cache_status(iint, function);
+ goto out_digsig;
+ }
+
+ template_desc = ima_template_desc_current();
+ if ((action & IMA_APPRAISE_SUBMASK) ||
+ strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0)
+ xattr_ptr = &xattr_value;
+
+ rc = ima_collect_measurement(iint, file, xattr_ptr, &xattr_len);
+ if (rc != 0) {
+ if (file->f_flags & O_DIRECT)
+ rc = (iint->flags & IMA_PERMIT_DIRECTIO) ? 0 : -EACCES;
+ goto out_digsig;
+ }
+
+ if (!pathname) /* ima_rdwr_violation possibly pre-fetched */
+ pathname = ima_d_path(&file->f_path, &pathbuf);
+
+ if (action & IMA_MEASURE)
+ ima_store_measurement(iint, file, pathname,
+ xattr_value, xattr_len);
+ if (action & IMA_APPRAISE_SUBMASK)
+ rc = ima_appraise_measurement(function, iint, file, pathname,
+ xattr_value, xattr_len, opened);
+ if (action & IMA_AUDIT)
+ ima_audit_measurement(iint, pathname);
+
+out_digsig:
+ if ((mask & MAY_WRITE) && (iint->flags & IMA_DIGSIG))
+ rc = -EACCES;
+ kfree(xattr_value);
+out_free:
+ if (pathbuf)
+ __putname(pathbuf);
+out:
+ mutex_unlock(&inode->i_mutex);
+ if ((rc && must_appraise) && (ima_appraise & IMA_APPRAISE_ENFORCE))
+ return -EACCES;
+ return 0;
+}
+
+/**
+ * ima_file_mmap - based on policy, collect/store measurement.
+ * @file: pointer to the file to be measured (May be NULL)
+ * @prot: contains the protection that will be applied by the kernel.
+ *
+ * Measure files being mmapped executable based on the ima_must_measure()
+ * policy decision.
+ *
+ * On success return 0. On integrity appraisal error, assuming the file
+ * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
+ */
+int ima_file_mmap(struct file *file, unsigned long prot)
+{
+ if (file && (prot & PROT_EXEC))
+ return process_measurement(file, MAY_EXEC, MMAP_CHECK, 0);
+ return 0;
+}
+
+/**
+ * ima_bprm_check - based on policy, collect/store measurement.
+ * @bprm: contains the linux_binprm structure
+ *
+ * The OS protects against an executable file, already open for write,
+ * from being executed in deny_write_access() and an executable file,
+ * already open for execute, from being modified in get_write_access().
+ * So we can be certain that what we verify and measure here is actually
+ * what is being executed.
+ *
+ * On success return 0. On integrity appraisal error, assuming the file
+ * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
+ */
+int ima_bprm_check(struct linux_binprm *bprm)
+{
+ return process_measurement(bprm->file, MAY_EXEC, BPRM_CHECK, 0);
+}
+
+/**
+ * ima_path_check - based on policy, collect/store measurement.
+ * @file: pointer to the file to be measured
+ * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE
+ *
+ * Measure files based on the ima_must_measure() policy decision.
+ *
+ * On success return 0. On integrity appraisal error, assuming the file
+ * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
+ */
+int ima_file_check(struct file *file, int mask, int opened)
+{
+ return process_measurement(file,
+ mask & (MAY_READ | MAY_WRITE | MAY_EXEC),
+ FILE_CHECK, opened);
+}
+EXPORT_SYMBOL_GPL(ima_file_check);
+
+/**
+ * ima_module_check - based on policy, collect/store/appraise measurement.
+ * @file: pointer to the file to be measured/appraised
+ *
+ * Measure/appraise kernel modules based on policy.
+ *
+ * On success return 0. On integrity appraisal error, assuming the file
+ * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
+ */
+int ima_module_check(struct file *file)
+{
+ if (!file) {
+#ifndef CONFIG_MODULE_SIG_FORCE
+ if ((ima_appraise & IMA_APPRAISE_MODULES) &&
+ (ima_appraise & IMA_APPRAISE_ENFORCE))
+ return -EACCES; /* INTEGRITY_UNKNOWN */
+#endif
+ return 0; /* We rely on module signature checking */
+ }
+ return process_measurement(file, MAY_EXEC, MODULE_CHECK, 0);
+}
+
+int ima_fw_from_file(struct file *file, char *buf, size_t size)
+{
+ if (!file) {
+ if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
+ (ima_appraise & IMA_APPRAISE_ENFORCE))
+ return -EACCES; /* INTEGRITY_UNKNOWN */
+ return 0;
+ }
+ return process_measurement(file, MAY_EXEC, FIRMWARE_CHECK, 0);
+}
+
+static int __init init_ima(void)
+{
+ int error;
+
+ hash_setup(CONFIG_IMA_DEFAULT_HASH);
+ error = ima_init();
+ if (!error) {
+ ima_initialized = 1;
+ ima_update_policy_flag();
+ }
+ return error;
+}
+
+late_initcall(init_ima); /* Start IMA after the TPM is available */
+
+MODULE_DESCRIPTION("Integrity Measurement Architecture");
+MODULE_LICENSE("GPL");