1 files changed, 241 insertions, 0 deletions
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
new file mode 100644
index 00000000..1eff5cb0
--- /dev/null
+++ b/security/integrity/ima/ima_main.c
@@ -0,0 +1,241 @@
+/*
+ * 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/ima.h>
+
+#include "ima.h"
+
+int ima_initialized;
+
+char *ima_hash = "sha1";
+static int __init hash_setup(char *str)
+{
+	if (strncmp(str, "md5", 3) == 0)
+		ima_hash = "md5";
+	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 dentry *dentry = file->f_path.dentry;
+	struct inode *inode = dentry->d_inode;
+	fmode_t mode = file->f_mode;
+	int rc;
+	bool send_tomtou = false, send_writers = false;
+
+	if (!S_ISREG(inode->i_mode) || !ima_initialized)
+		return;
+
+	mutex_lock(&inode->i_mutex);	/* file metadata: permissions, xattr */
+
+	if (mode & FMODE_WRITE) {
+		if (atomic_read(&inode->i_readcount) && IS_IMA(inode))
+			send_tomtou = true;
+		goto out;
+	}
+
+	rc = ima_must_measure(inode, MAY_READ, FILE_CHECK);
+	if (rc < 0)
+		goto out;
+
+	if (atomic_read(&inode->i_writecount) > 0)
+		send_writers = true;
+out:
+	mutex_unlock(&inode->i_mutex);
+
+	if (send_tomtou)
+		ima_add_violation(inode, dentry->d_name.name, "invalid_pcr",
+				  "ToMToU");
+	if (send_writers)
+		ima_add_violation(inode, dentry->d_name.name, "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;
+
+	mutex_lock(&iint->mutex);
+	if (mode & FMODE_WRITE &&
+	    atomic_read(&inode->i_writecount) == 1 &&
+	    iint->version != inode->i_version)
+		iint->flags &= ~IMA_MEASURED;
+	mutex_unlock(&iint->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->f_dentry->d_inode;
+	struct integrity_iint_cache *iint;
+
+	if (!iint_initialized || !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, const unsigned char *filename,
+			       int mask, int function)
+{
+	struct inode *inode = file->f_dentry->d_inode;
+	struct integrity_iint_cache *iint;
+	int rc = 0;
+
+	if (!ima_initialized || !S_ISREG(inode->i_mode))
+		return 0;
+
+	rc = ima_must_measure(inode, mask, function);
+	if (rc != 0)
+		return rc;
+retry:
+	iint = integrity_iint_find(inode);
+	if (!iint) {
+		rc = integrity_inode_alloc(inode);
+		if (!rc || rc == -EEXIST)
+			goto retry;
+		return rc;
+	}
+
+	mutex_lock(&iint->mutex);
+
+	rc = iint->flags & IMA_MEASURED ? 1 : 0;
+	if (rc != 0)
+		goto out;
+
+	rc = ima_collect_measurement(iint, file);
+	if (!rc)
+		ima_store_measurement(iint, file, filename);
+out:
+	mutex_unlock(&iint->mutex);
+	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;
+}
+
+/**
+ * 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.
+ *
+ * Always return 0 and audit dentry_open failures.
+ * (Return code will be based upon measurement appraisal.)
+ */
+int ima_file_check(struct file *file, int mask)
+{
+	int rc;
+
+	ima_rdwr_violation_check(file);
+	rc = process_measurement(file, file->f_dentry->d_name.name,
+				 mask & (MAY_READ | MAY_WRITE | MAY_EXEC),
+				 FILE_CHECK);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(ima_file_check);
+
+static int __init init_ima(void)
+{
+	int error;
+
+	error = ima_init();
+	ima_initialized = 1;
+	return error;
+}
+
+static void __exit cleanup_ima(void)
+{
+	ima_cleanup();
+}
+
+late_initcall(init_ima);	/* Start IMA after the TPM is available */
+
+MODULE_DESCRIPTION("Integrity Measurement Architecture");
+MODULE_LICENSE("GPL");