1 files changed, 280 insertions, 0 deletions
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
new file mode 100644
index 0000000..53cee4c
--- /dev/null
+++ b/security/integrity/ima/ima_main.c
@@ -0,0 +1,280 @@
+/*
+ * 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_path_check.
+ */
+#include <linux/module.h>
+#include <linux/file.h>
+#include <linux/binfmts.h>
+#include <linux/mount.h>
+#include <linux/mman.h>
+
+#include "ima.h"
+
+int ima_initialized;
+
+char *ima_hash = "sha1";
+static int __init hash_setup(char *str)
+{
+	const char *op = "hash_setup";
+	const char *hash = "sha1";
+	int result = 0;
+	int audit_info = 0;
+
+	if (strncmp(str, "md5", 3) == 0) {
+		hash = "md5";
+		ima_hash = str;
+	} else if (strncmp(str, "sha1", 4) != 0) {
+		hash = "invalid_hash_type";
+		result = 1;
+	}
+	integrity_audit_msg(AUDIT_INTEGRITY_HASH, NULL, NULL, op, hash,
+			    result, audit_info);
+	return 1;
+}
+__setup("ima_hash=", hash_setup);
+
+/**
+ * ima_file_free - called on __fput()
+ * @file: pointer to file structure being freed
+ *
+ * Flag files that changed, based on i_version;
+ * and decrement the iint readcount/writecount.
+ */
+void ima_file_free(struct file *file)
+{
+	struct inode *inode = file->f_dentry->d_inode;
+	struct ima_iint_cache *iint;
+
+	if (!ima_initialized || !S_ISREG(inode->i_mode))
+		return;
+	iint = ima_iint_find_get(inode);
+	if (!iint)
+		return;
+
+	mutex_lock(&iint->mutex);
+	if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
+		iint->readcount--;
+
+	if (file->f_mode & FMODE_WRITE) {
+		iint->writecount--;
+		if (iint->writecount == 0) {
+			if (iint->version != inode->i_version)
+				iint->flags &= ~IMA_MEASURED;
+		}
+	}
+	mutex_unlock(&iint->mutex);
+	kref_put(&iint->refcount, iint_free);
+}
+
+/* ima_read_write_check - reflect possible reading/writing errors in the PCR.
+ *
+ * When opening a file for read, if the file is already open for write,
+ * the file could change, resulting in a file measurement error.
+ *
+ * Opening a file for write, if the file is already open for read, results
+ * in a time of measure, time of use (ToMToU) error.
+ *
+ * In either case invalidate the PCR.
+ */
+enum iint_pcr_error { TOMTOU, OPEN_WRITERS };
+static void ima_read_write_check(enum iint_pcr_error error,
+				 struct ima_iint_cache *iint,
+				 struct inode *inode,
+				 const unsigned char *filename)
+{
+	switch (error) {
+	case TOMTOU:
+		if (iint->readcount > 0)
+			ima_add_violation(inode, filename, "invalid_pcr",
+					  "ToMToU");
+		break;
+	case OPEN_WRITERS:
+		if (iint->writecount > 0)
+			ima_add_violation(inode, filename, "invalid_pcr",
+					  "open_writers");
+		break;
+	}
+}
+
+static int get_path_measurement(struct ima_iint_cache *iint, struct file *file,
+				const unsigned char *filename)
+{
+	int rc = 0;
+
+	if (IS_ERR(file)) {
+		pr_info("%s dentry_open failed\n", filename);
+		return rc;
+	}
+	iint->readcount++;
+
+	rc = ima_collect_measurement(iint, file);
+	if (!rc)
+		ima_store_measurement(iint, file, filename);
+	return rc;
+}
+
+/**
+ * ima_path_check - based on policy, collect/store measurement.
+ * @path: contains a pointer to the path to be measured
+ * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE
+ *
+ * Measure the file being open for readonly, based on the
+ * ima_must_measure() policy decision.
+ *
+ * Keep read/write counters for all files, but 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.
+ *
+ * Return 0 on success, an error code on failure.
+ * (Based on the results of appraise_measurement().)
+ */
+int ima_path_check(struct path *path, int mask)
+{
+	struct inode *inode = path->dentry->d_inode;
+	struct ima_iint_cache *iint;
+	struct file *file = NULL;
+	int rc;
+
+	if (!ima_initialized || !S_ISREG(inode->i_mode))
+		return 0;
+	iint = ima_iint_find_insert_get(inode);
+	if (!iint)
+		return 0;
+
+	mutex_lock(&iint->mutex);
+	if ((mask & MAY_WRITE) || (mask == 0))
+		iint->writecount++;
+	else if (mask & (MAY_READ | MAY_EXEC))
+		iint->readcount++;
+
+	rc = ima_must_measure(iint, inode, MAY_READ, PATH_CHECK);
+	if (rc < 0)
+		goto out;
+
+	if ((mask & MAY_WRITE) || (mask == 0))
+		ima_read_write_check(TOMTOU, iint, inode,
+				     path->dentry->d_name.name);
+
+	if ((mask & (MAY_WRITE | MAY_READ | MAY_EXEC)) != MAY_READ)
+		goto out;
+
+	ima_read_write_check(OPEN_WRITERS, iint, inode,
+			     path->dentry->d_name.name);
+	if (!(iint->flags & IMA_MEASURED)) {
+		struct dentry *dentry = dget(path->dentry);
+		struct vfsmount *mnt = mntget(path->mnt);
+
+		file = dentry_open(dentry, mnt, O_RDONLY, current->cred);
+		rc = get_path_measurement(iint, file, dentry->d_name.name);
+	}
+out:
+	mutex_unlock(&iint->mutex);
+	if (file)
+		fput(file);
+	kref_put(&iint->refcount, iint_free);
+	return 0;
+}
+
+static int process_measurement(struct file *file, const unsigned char *filename,
+			       int mask, int function)
+{
+	struct inode *inode = file->f_dentry->d_inode;
+	struct ima_iint_cache *iint;
+	int rc;
+
+	if (!ima_initialized || !S_ISREG(inode->i_mode))
+		return 0;
+	iint = ima_iint_find_insert_get(inode);
+	if (!iint)
+		return -ENOMEM;
+
+	mutex_lock(&iint->mutex);
+	rc = ima_must_measure(iint, inode, mask, function);
+	if (rc != 0)
+		goto out;
+
+	rc = ima_collect_measurement(iint, file);
+	if (!rc)
+		ima_store_measurement(iint, file, filename);
+out:
+	mutex_unlock(&iint->mutex);
+	kref_put(&iint->refcount, iint_free);
+	return rc;
+}
+
+/**
+ * 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.
+ *
+ * Return 0 on success, an error code on failure.
+ * (Based on the results of appraise_measurement().)
+ */
+int ima_file_mmap(struct file *file, unsigned long prot)
+{
+	int rc;
+
+	if (!file)
+		return 0;
+	if (prot & PROT_EXEC)
+		rc = process_measurement(file, file->f_dentry->d_name.name,
+					 MAY_EXEC, FILE_MMAP);
+	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.
+ *
+ * Return 0 on success, an error code on failure.
+ * (Based on the results of appraise_measurement().)
+ */
+int ima_bprm_check(struct linux_binprm *bprm)
+{
+	int rc;
+
+	rc = process_measurement(bprm->file, bprm->filename,
+				 MAY_EXEC, BPRM_CHECK);
+	return 0;
+}
+
+static int __init init_ima(void)
+{
+	int error;
+
+	ima_iintcache_init();
+	error = ima_init();
+	ima_initialized = 1;
+	return error;
+}
+
+late_initcall(init_ima);	/* Start IMA after the TPM is available */
+
+MODULE_DESCRIPTION("Integrity Measurement Architecture");
+MODULE_LICENSE("GPL");