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-rw-r--r--security/integrity/iint.c261
1 files changed, 261 insertions, 0 deletions
diff --git a/security/integrity/iint.c b/security/integrity/iint.c
new file mode 100644
index 000000000..cb251ab0e
--- /dev/null
+++ b/security/integrity/iint.c
@@ -0,0 +1,261 @@
+// 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;
+
+ /*
+ * The integrity's "iint_cache" is initialized at security_init(),
+ * unless it is not included in the ordered list of LSMs enabled
+ * on the boot command line.
+ */
+ if (!iint_cache)
+ panic("%s: lsm=integrity required.\n", __func__);
+
+ 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,
+};
+
+
+/*
+ * 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)