1 files changed, 254 insertions, 0 deletions
diff --git a/security/integrity/iint.c b/security/integrity/iint.c
new file mode 100644
index 000000000..27ea19fb1
--- /dev/null
+++ b/security/integrity/iint.c
@@ -0,0 +1,254 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2008 IBM Corporation
+ *
+ * Authors:
+ * Mimi Zohar <zohar@us.ibm.com>
+ *
+ * File: integrity_iint.c
+ *	- implements the integrity hooks: integrity_inode_alloc,
+ *	  integrity_inode_free
+ *	- cache integrity information associated with an inode
+ *	  using a rbtree tree.
+ */
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/spinlock.h>
+#include <linux/rbtree.h>
+#include <linux/file.h>
+#include <linux/uaccess.h>
+#include <linux/security.h>
+#include <linux/lsm_hooks.h>
+#include "integrity.h"
+
+static struct rb_root integrity_iint_tree = RB_ROOT;
+static DEFINE_RWLOCK(integrity_iint_lock);
+static struct kmem_cache *iint_cache __read_mostly;
+
+struct dentry *integrity_dir;
+
+/*
+ * __integrity_iint_find - return the iint associated with an inode
+ */
+static struct integrity_iint_cache *__integrity_iint_find(struct inode *inode)
+{
+	struct integrity_iint_cache *iint;
+	struct rb_node *n = integrity_iint_tree.rb_node;
+
+	while (n) {
+		iint = rb_entry(n, struct integrity_iint_cache, rb_node);
+
+		if (inode < iint->inode)
+			n = n->rb_left;
+		else if (inode > iint->inode)
+			n = n->rb_right;
+		else
+			return iint;
+	}
+
+	return NULL;
+}
+
+/*
+ * integrity_iint_find - return the iint associated with an inode
+ */
+struct integrity_iint_cache *integrity_iint_find(struct inode *inode)
+{
+	struct integrity_iint_cache *iint;
+
+	if (!IS_IMA(inode))
+		return NULL;
+
+	read_lock(&integrity_iint_lock);
+	iint = __integrity_iint_find(inode);
+	read_unlock(&integrity_iint_lock);
+
+	return iint;
+}
+
+#define IMA_MAX_NESTING (FILESYSTEM_MAX_STACK_DEPTH+1)
+
+/*
+ * It is not clear that IMA should be nested at all, but as long is it measures
+ * files both on overlayfs and on underlying fs, we need to annotate the iint
+ * mutex to avoid lockdep false positives related to IMA + overlayfs.
+ * See ovl_lockdep_annotate_inode_mutex_key() for more details.
+ */
+static inline void iint_lockdep_annotate(struct integrity_iint_cache *iint,
+					 struct inode *inode)
+{
+#ifdef CONFIG_LOCKDEP
+	static struct lock_class_key iint_mutex_key[IMA_MAX_NESTING];
+
+	int depth = inode->i_sb->s_stack_depth;
+
+	if (WARN_ON_ONCE(depth < 0 || depth >= IMA_MAX_NESTING))
+		depth = 0;
+
+	lockdep_set_class(&iint->mutex, &iint_mutex_key[depth]);
+#endif
+}
+
+static void iint_init_always(struct integrity_iint_cache *iint,
+			     struct inode *inode)
+{
+	iint->ima_hash = NULL;
+	iint->version = 0;
+	iint->flags = 0UL;
+	iint->atomic_flags = 0UL;
+	iint->ima_file_status = INTEGRITY_UNKNOWN;
+	iint->ima_mmap_status = INTEGRITY_UNKNOWN;
+	iint->ima_bprm_status = INTEGRITY_UNKNOWN;
+	iint->ima_read_status = INTEGRITY_UNKNOWN;
+	iint->ima_creds_status = INTEGRITY_UNKNOWN;
+	iint->evm_status = INTEGRITY_UNKNOWN;
+	iint->measured_pcrs = 0;
+	mutex_init(&iint->mutex);
+	iint_lockdep_annotate(iint, inode);
+}
+
+static void iint_free(struct integrity_iint_cache *iint)
+{
+	kfree(iint->ima_hash);
+	mutex_destroy(&iint->mutex);
+	kmem_cache_free(iint_cache, iint);
+}
+
+/**
+ * integrity_inode_get - find or allocate an iint associated with an inode
+ * @inode: pointer to the inode
+ * @return: allocated iint
+ *
+ * Caller must lock i_mutex
+ */
+struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
+{
+	struct rb_node **p;
+	struct rb_node *node, *parent = NULL;
+	struct integrity_iint_cache *iint, *test_iint;
+
+	iint = integrity_iint_find(inode);
+	if (iint)
+		return iint;
+
+	iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
+	if (!iint)
+		return NULL;
+
+	iint_init_always(iint, inode);
+
+	write_lock(&integrity_iint_lock);
+
+	p = &integrity_iint_tree.rb_node;
+	while (*p) {
+		parent = *p;
+		test_iint = rb_entry(parent, struct integrity_iint_cache,
+				     rb_node);
+		if (inode < test_iint->inode) {
+			p = &(*p)->rb_left;
+		} else if (inode > test_iint->inode) {
+			p = &(*p)->rb_right;
+		} else {
+			write_unlock(&integrity_iint_lock);
+			kmem_cache_free(iint_cache, iint);
+			return test_iint;
+		}
+	}
+
+	iint->inode = inode;
+	node = &iint->rb_node;
+	inode->i_flags |= S_IMA;
+	rb_link_node(node, parent, p);
+	rb_insert_color(node, &integrity_iint_tree);
+
+	write_unlock(&integrity_iint_lock);
+	return iint;
+}
+
+/**
+ * integrity_inode_free - called on security_inode_free
+ * @inode: pointer to the inode
+ *
+ * Free the integrity information(iint) associated with an inode.
+ */
+void integrity_inode_free(struct inode *inode)
+{
+	struct integrity_iint_cache *iint;
+
+	if (!IS_IMA(inode))
+		return;
+
+	write_lock(&integrity_iint_lock);
+	iint = __integrity_iint_find(inode);
+	rb_erase(&iint->rb_node, &integrity_iint_tree);
+	write_unlock(&integrity_iint_lock);
+
+	iint_free(iint);
+}
+
+static void iint_init_once(void *foo)
+{
+	struct integrity_iint_cache *iint = (struct integrity_iint_cache *) foo;
+
+	memset(iint, 0, sizeof(*iint));
+}
+
+static int __init integrity_iintcache_init(void)
+{
+	iint_cache =
+	    kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
+			      0, SLAB_PANIC, iint_init_once);
+	return 0;
+}
+DEFINE_LSM(integrity) = {
+	.name = "integrity",
+	.init = integrity_iintcache_init,
+	.order = LSM_ORDER_LAST,
+};
+
+
+/*
+ * integrity_kernel_read - read data from the file
+ *
+ * This is a function for reading file content instead of kernel_read().
+ * It does not perform locking checks to ensure it cannot be blocked.
+ * It does not perform security checks because it is irrelevant for IMA.
+ *
+ */
+int integrity_kernel_read(struct file *file, loff_t offset,
+			  void *addr, unsigned long count)
+{
+	return __kernel_read(file, addr, count, &offset);
+}
+
+/*
+ * integrity_load_keys - load integrity keys hook
+ *
+ * Hooks is called from init/main.c:kernel_init_freeable()
+ * when rootfs is ready
+ */
+void __init integrity_load_keys(void)
+{
+	ima_load_x509();
+
+	if (!IS_ENABLED(CONFIG_IMA_LOAD_X509))
+		evm_load_x509();
+}
+
+static int __init integrity_fs_init(void)
+{
+	integrity_dir = securityfs_create_dir("integrity", NULL);
+	if (IS_ERR(integrity_dir)) {
+		int ret = PTR_ERR(integrity_dir);
+
+		if (ret != -ENODEV)
+			pr_err("Unable to create integrity sysfs dir: %d\n",
+			       ret);
+		integrity_dir = NULL;
+		return ret;
+	}
+
+	return 0;
+}
+
+late_initcall(integrity_fs_init)