[PATCH 4/4] integrity: IMA radix tree
From: Mimi Zohar
Date: Wed Nov 12 2008 - 22:49:05 EST
This version stores integrity information associated with an inode
in a radix tree in order to avoid bloating the in memory inode.
As entries can not be added to the radix tree at security_initcall,
this version removes the dual stage initialization. Allocating and
freeing the memory continues to be done at inode_alloc and file_free,
respectively, except for inodes created before late_initcall.
Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxx>
---
diff --git a/include/linux/fs.h b/include/linux/fs.h
index bc6460c..0dcdd94 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -683,9 +683,6 @@ struct inode {
#ifdef CONFIG_SECURITY
void *i_security;
#endif
-#ifdef CONFIG_INTEGRITY
- void *i_integrity;
-#endif
void *i_private; /* fs or device private pointer */
};
diff --git a/security/integrity/ima/Makefile b/security/integrity/ima/Makefile
index f3aced4..959ae66 100644
--- a/security/integrity/ima/Makefile
+++ b/security/integrity/ima/Makefile
@@ -6,4 +6,4 @@
obj-$(CONFIG_IMA) += ima.o
ima-y := ima_fs.o ima_queue.o ima_init.o ima_main.o ima_crypto.o ima_api.o \
- ima_policy.o
+ ima_policy.o ima_iint.o
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 9a24305..09a5e1a 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -92,7 +92,6 @@ void ima_store_measurement(void *d);
void ima_template_show(struct seq_file *m, void *e,
enum integrity_show_type show);
-
/*
* used to protect h_table and sha_table
*/
@@ -109,7 +108,7 @@ extern struct ima_h_table ima_htable;
static inline unsigned long IMA_HASH_KEY(u8 *digest)
{
- return(hash_long(*digest, IMA_HASH_BITS));
+ return (hash_long(*digest, IMA_HASH_BITS));
}
/* TPM "Glue" definitions */
@@ -145,11 +144,36 @@ struct ima_iint_cache {
u8 hmac[IMA_DIGEST_SIZE];
u8 digest[IMA_DIGEST_SIZE];
struct mutex mutex;
+ atomic_t refcount;
};
#define IMA_IINT_INIT 1
#define IMA_MUST_MEASURE 2
#define IMA_MEASURED 4
+void ima_iint_init(void);
+struct ima_iint_cache * ima_iint_lookup(struct inode *inode);
+int ima_iint_insert(struct inode *inode);
+void ima_iint_delete(struct inode *inode);
+
+static inline void iint_get(struct ima_iint_cache *iint)
+{
+ atomic_inc(&iint->refcount);
+}
+
+/*
+ * When iint->refcounter goes to 0, free iint.
+ *
+ * When inode_alloc_integrity starts at late_initcall,
+ * iint can be NULl.
+ */
+static inline void iint_put(struct ima_iint_cache *iint)
+{
+ if (!iint)
+ return;
+ if (atomic_dec_and_test(&iint->refcount))
+ kfree(iint);
+}
+
/* LSM based policy rules require audit */
#ifdef CONFIG_IMA_LSM_RULES
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 504c195..5b0b2f9 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -266,9 +266,35 @@ int ima_must_measure(void *template_data)
if (skip_measurement(data->inode, data->mask))
return -EPERM;
- iint = inode->i_integrity;
- mutex_lock(&iint->mutex);
+ rcu_read_lock();
+ iint = ima_iint_lookup(inode);
+ if (iint)
+ iint_get(iint);
+ rcu_read_unlock();
+
+ if (!iint) {
+ int rc;
+
+ /* Most insertions are done at inode_alloc,
+ * except those allocated before late_initcall.
+ * Can't initialize at security_initcall,
+ * got to wait at least until proc_init.
+ */
+ rc = ima_iint_insert(inode);
+ if (rc < 0)
+ return rc;
+
+ rcu_read_lock();
+ iint = ima_iint_lookup(inode);
+ if (!iint) {
+ rcu_read_unlock();
+ return -ENOMEM;
+ }
+ iint_get(iint);
+ rcu_read_unlock();
+ }
+ mutex_lock(&iint->mutex);
/* short circuit out of here, if iint initialized
* and either no measurement required or already measured.
*/
@@ -290,6 +316,7 @@ int ima_must_measure(void *template_data)
iint->flags |= IMA_IINT_INIT;
}
mutex_unlock(&iint->mutex);
+ iint_put(iint);
return must_measure;
}
@@ -314,7 +341,15 @@ int ima_collect_measurement(void *template_data)
if (!inode || !dentry)
return -EINVAL;
- iint = inode->i_integrity;
+ rcu_read_lock();
+ iint = ima_iint_lookup(inode);
+ if (!iint) {
+ rcu_read_unlock();
+ return -ENOMEM;
+ }
+ iint_get(iint);
+ rcu_read_unlock();
+
mutex_lock(&iint->mutex);
if (!(iint->flags & IMA_MEASURED)) {
memset(iint->digest, 0, IMA_DIGEST_SIZE);
@@ -322,6 +357,7 @@ int ima_collect_measurement(void *template_data)
} else
result = -EEXIST;
mutex_unlock(&iint->mutex);
+ iint_put(iint);
return result;
}
@@ -344,7 +380,15 @@ void ima_store_measurement(void *template_data)
struct ima_args_data *data = &idata->data.args;
struct ima_iint_cache *iint;
- iint = data->inode->i_integrity;
+ rcu_read_lock();
+ iint = ima_iint_lookup(data->inode);
+ if (!iint) {
+ rcu_read_unlock();
+ return;
+ }
+ iint_get(iint);
+ rcu_read_unlock();
+
mutex_lock(&iint->mutex);
if (iint->flags & IMA_MEASURED) {
mutex_unlock(&iint->mutex);
@@ -358,6 +402,7 @@ void ima_store_measurement(void *template_data)
iint->version = data->inode->i_version;
}
mutex_unlock(&iint->mutex);
+ iint_put(iint);
} else if (idata->type == IMA_TEMPLATE) {
struct ima_store_data *template = (struct ima_store_data *)
&idata->data.template;
diff --git a/security/integrity/ima/ima_iint.c b/security/integrity/ima/ima_iint.c
new file mode 100644
index 0000000..f7f6673
--- /dev/null
+++ b/security/integrity/ima/ima_iint.c
@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2008 IBM Corporation
+ *
+ * Authors:
+ * Mimi Zohar <zohar@xxxxxxxxxx>
+ *
+ * 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_iint.c
+ * cache integrity information associated with an inode
+ * using a radix tree.
+ */
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/radix-tree.h>
+#include "ima.h"
+
+static struct radix_tree_root ima_iint_store;
+DEFINE_SPINLOCK(ima_iint_lock);
+
+void ima_iint_init(void)
+{
+ INIT_RADIX_TREE(&ima_iint_store, GFP_ATOMIC);
+}
+
+/* Call with rcu_read_lock */
+struct ima_iint_cache * ima_iint_lookup(struct inode *inode)
+{
+ return radix_tree_lookup(&ima_iint_store, (unsigned long)inode);
+}
+
+int ima_iint_insert(struct inode *inode)
+{
+ struct ima_iint_cache *iint;
+ int rc = 0;
+
+ iint = kzalloc(sizeof(*iint), GFP_KERNEL);
+ if (!iint)
+ return -ENOMEM;
+ mutex_init(&iint->mutex);
+ atomic_set(&iint->refcount, 1);
+ iint->version = inode->i_version;
+
+ if ((rc = radix_tree_preload(GFP_KERNEL)) < 0) {
+ printk(KERN_INFO "%s: radix_tree_preload\n", __FUNCTION__);
+ kfree(iint);
+ return rc;
+ }
+
+ spin_lock(&ima_iint_lock);
+ rc = radix_tree_insert(&ima_iint_store, (unsigned long)inode, iint);
+ spin_unlock(&ima_iint_lock);
+ radix_tree_preload_end();
+ return rc;
+}
+
+void ima_iint_delete(struct inode *inode)
+{
+ struct ima_iint_cache *iint;
+
+ spin_lock(&ima_iint_lock);
+ iint = radix_tree_delete(&ima_iint_store, (unsigned long)inode);
+ spin_unlock(&ima_iint_lock);
+ iint_put(iint);
+}
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 2b90df9..e36eef8 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -28,7 +28,6 @@
#include "ima.h"
-static bool ima_initialized = false;
char *ima_hash = "sha1";
static int __init hash_setup(char *str)
{
@@ -102,32 +101,32 @@ static void ima_file_free(struct file *file)
return;
if ((file->f_mode & FMODE_WRITE) &&
(atomic_read(&inode->i_writecount) == 1)) {
- iint = inode->i_integrity;
+ rcu_read_lock();
+ iint = ima_iint_lookup(inode);
+ if (!iint) {
+ rcu_read_unlock();
+ return;
+ }
+ iint_get(iint);
+ rcu_read_unlock();
+
mutex_lock(&iint->mutex);
if (iint->version != inode->i_version)
iint->flags &= ~IMA_MEASURED;
mutex_unlock(&iint->mutex);
+ iint_put(iint);
}
}
/**
- * ima_alloc_integrity - allocate and attach an integrity structure
+ * ima_alloc_integrity - allocate and insert an integrity structure
* @inode: the inode structure
*
* Returns 0 on success, -ENOMEM on failure
*/
static int ima_inode_alloc_integrity(struct inode *inode)
{
- struct ima_iint_cache *iint;
-
- iint = kzalloc(sizeof(*iint), GFP_KERNEL);
- if (!iint)
- return -ENOMEM;
-
- mutex_init(&iint->mutex);
- inode->i_integrity = iint;
- iint->version = inode->i_version;
- return 0;
+ return ima_iint_insert(inode);
}
/**
@@ -136,12 +135,7 @@ static int ima_inode_alloc_integrity(struct inode *inode)
*/
static void ima_inode_free_integrity(struct inode *inode)
{
- struct ima_iint_cache *iint = inode->i_integrity;
-
- if (iint) {
- inode->i_integrity = NULL;
- kfree(iint);
- }
+ ima_iint_delete(inode);
}
/**
@@ -168,9 +162,6 @@ static int ima_nameidata_check_integrity(struct nameidata *nd, int mask)
struct dentry *dentry;
struct inode *inode;
- if (!ima_initialized)
- return 0;
-
memset(&idata, 0, sizeof idata);
ima_fixup_argsdata(data, NULL, &nd->path, mask, INODE_PERMISSION);
inode = data->inode;
@@ -238,8 +229,6 @@ static int ima_file_mmap(struct file *file, unsigned long prot)
struct ima_args_data *data = &idata.data.args;
int rc = 0;
- if (!ima_initialized)
- return 0;
if (!file || !file->f_dentry)
return rc;
if (!(prot & VM_EXEC))
@@ -279,8 +268,6 @@ static int ima_bprm_check_integrity(struct linux_binprm *bprm)
struct ima_args_data *data = &idata.data.args;
int rc = 0;
- if (!ima_initialized)
- return 0;
ima_fixup_argsdata(data, bprm->file, NULL, MAY_EXEC, BPRM_CHECK);
data->filename = bprm->filename;
@@ -309,30 +296,24 @@ static const struct integrity_operations ima_base_ops = {
.file_free_integrity = ima_file_free,
};
-/* Register the integrity ops early so that i_integrity is
- * allocated at inode initialization.
+/* After the TPM is available, start IMA
*/
-static int __init init_ops(void)
+static int __init init_ima(void)
{
int error;
+ ima_iint_init(); /* Can't register early when using radix_tree */
+ error = ima_init();
+ if (error)
+ goto out;
+
if (ima_base_hooks)
error = register_integrity(&ima_base_ops);
else
error = register_integrity(&ima_integrity_ops);
- return error;
-}
-
-/* After the TPM is available, start IMA
- */
-static int __init init_ima(void)
-{
- int error;
-
- error = ima_init();
if (error)
goto out;
- ima_initialized = true;
+
integrity_register_template("ima", &ima_template_ops);
out:
return error;
@@ -345,7 +326,6 @@ static void __exit cleanup_ima(void)
ima_cleanup();
}
-security_initcall(init_ops); /* Register the integrity ops early */
late_initcall(init_ima); /* Start IMA after the TPM is available */
module_exit(cleanup_ima);
--
1.5.5.1
--
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