Merge branch 'ima-memory-use-fixes'

* ima-memory-use-fixes:
  IMA: fix the ToMToU logic
  IMA: explicit IMA i_flag to remove global lock on inode_delete
  IMA: drop refcnt from ima_iint_cache since it isn't needed
  IMA: only allocate iint when needed
  IMA: move read counter into struct inode
  IMA: use i_writecount rather than a private counter
  IMA: use inode->i_lock to protect read and write counters
  IMA: convert internal flags from long to char
  IMA: use unsigned int instead of long for counters
  IMA: drop the inode opencount since it isn't needed for operation
  IMA: use rbtree instead of radix tree for inode information cache

4 files changed, 194 insertions, 168 deletions

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 3fbcd1dda0ef..ac79032bdf23 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -70,6 +70,7 @@ int ima_init(void);
 void ima_cleanup(void);
 int ima_fs_init(void);
 void ima_fs_cleanup(void);
+int ima_inode_alloc(struct inode *inode);
 int ima_add_template_entry(struct ima_template_entry *entry, int violation,
 			   const char *op, struct inode *inode);
 int ima_calc_hash(struct file *file, char *digest);
@@ -96,19 +97,16 @@ static inline unsigned long ima_hash_key(u8 *digest)
 }
 
 /* iint cache flags */
-#define IMA_MEASURED		1
+#define IMA_MEASURED		0x01
 
 /* integrity data associated with an inode */
 struct ima_iint_cache {
+	struct rb_node rb_node; /* rooted in ima_iint_tree */
+	struct inode *inode;	/* back pointer to inode in question */
 	u64 version;		/* track inode changes */
-	unsigned long flags;
+	unsigned char flags;
 	u8 digest[IMA_DIGEST_SIZE];
 	struct mutex mutex;	/* protects: version, flags, digest */
-	long readcount;		/* measured files readcount */
-	long writecount;	/* measured files writecount */
-	long opencount;		/* opens reference count */
-	struct kref refcount;	/* ima_iint_cache reference count */
-	struct rcu_head rcu;
 };
 
 /* LIM API function definitions */
@@ -122,13 +120,11 @@ int ima_store_template(struct ima_template_entry *entry, int violation,
 void ima_template_show(struct seq_file *m, void *e,
 		       enum ima_show_type show);
 
-/* radix tree calls to lookup, insert, delete
+/* rbtree tree calls to lookup, insert, delete
  * integrity data associated with an inode.
  */
 struct ima_iint_cache *ima_iint_insert(struct inode *inode);
-struct ima_iint_cache *ima_iint_find_get(struct inode *inode);
-void iint_free(struct kref *kref);
-void iint_rcu_free(struct rcu_head *rcu);
+struct ima_iint_cache *ima_iint_find(struct inode *inode);
 
 /* IMA policy related functions */
 enum ima_hooks { FILE_CHECK = 1, FILE_MMAP, BPRM_CHECK };
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 52015d098fdf..d3963de6003d 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -116,7 +116,7 @@ int ima_must_measure(struct ima_iint_cache *iint, struct inode *inode,
 {
 	int must_measure;
 
-	if (iint->flags & IMA_MEASURED)
+	if (iint && iint->flags & IMA_MEASURED)
 		return 1;
 
 	must_measure = ima_match_policy(inode, function, mask);
diff --git a/security/integrity/ima/ima_iint.c b/security/integrity/ima/ima_iint.c
index afba4aef812f..c442e47b6785 100644
--- a/security/integrity/ima/ima_iint.c
+++ b/security/integrity/ima/ima_iint.c
@@ -12,98 +12,119 @@
  * File: ima_iint.c
  * 	- implements the IMA hooks: ima_inode_alloc, ima_inode_free
  *	- cache integrity information associated with an inode
- *	  using a radix tree.
+ *	  using a rbtree tree.
  */
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/spinlock.h>
-#include <linux/radix-tree.h>
+#include <linux/rbtree.h>
 #include "ima.h"
 
-RADIX_TREE(ima_iint_store, GFP_ATOMIC);
-DEFINE_SPINLOCK(ima_iint_lock);
+static struct rb_root ima_iint_tree = RB_ROOT;
+static DEFINE_SPINLOCK(ima_iint_lock);
 static struct kmem_cache *iint_cache __read_mostly;
 
 int iint_initialized = 0;
 
-/* ima_iint_find_get - return the iint associated with an inode
- *
- * ima_iint_find_get gets a reference to the iint. Caller must
- * remember to put the iint reference.
+/*
+ * __ima_iint_find - return the iint associated with an inode
  */
-struct ima_iint_cache *ima_iint_find_get(struct inode *inode)
+static struct ima_iint_cache *__ima_iint_find(struct inode *inode)
 {
 	struct ima_iint_cache *iint;
+	struct rb_node *n = ima_iint_tree.rb_node;
+
+	assert_spin_locked(&ima_iint_lock);
+
+	while (n) {
+		iint = rb_entry(n, struct ima_iint_cache, rb_node);
+
+		if (inode < iint->inode)
+			n = n->rb_left;
+		else if (inode > iint->inode)
+			n = n->rb_right;
+		else
+			break;
+	}
+	if (!n)
+		return NULL;
 
-	rcu_read_lock();
-	iint = radix_tree_lookup(&ima_iint_store, (unsigned long)inode);
-	if (!iint)
-		goto out;
-	kref_get(&iint->refcount);
-out:
-	rcu_read_unlock();
 	return iint;
 }
 
-/**
- * ima_inode_alloc - allocate an iint associated with an inode
- * @inode: pointer to the inode
+/*
+ * ima_iint_find - return the iint associated with an inode
  */
-int ima_inode_alloc(struct inode *inode)
+struct ima_iint_cache *ima_iint_find(struct inode *inode)
 {
-	struct ima_iint_cache *iint = NULL;
-	int rc = 0;
-
-	iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
-	if (!iint)
-		return -ENOMEM;
+	struct ima_iint_cache *iint;
 
-	rc = radix_tree_preload(GFP_NOFS);
-	if (rc < 0)
-		goto out;
+	if (!IS_IMA(inode))
+		return NULL;
 
 	spin_lock(&ima_iint_lock);
-	rc = radix_tree_insert(&ima_iint_store, (unsigned long)inode, iint);
+	iint = __ima_iint_find(inode);
 	spin_unlock(&ima_iint_lock);
-	radix_tree_preload_end();
-out:
-	if (rc < 0)
-		kmem_cache_free(iint_cache, iint);
 
-	return rc;
+	return iint;
 }
 
-/* iint_free - called when the iint refcount goes to zero */
-void iint_free(struct kref *kref)
+static void iint_free(struct ima_iint_cache *iint)
 {
-	struct ima_iint_cache *iint = container_of(kref, struct ima_iint_cache,
-						   refcount);
 	iint->version = 0;
 	iint->flags = 0UL;
-	if (iint->readcount != 0) {
-		printk(KERN_INFO "%s: readcount: %ld\n", __func__,
-		       iint->readcount);
-		iint->readcount = 0;
-	}
-	if (iint->writecount != 0) {
-		printk(KERN_INFO "%s: writecount: %ld\n", __func__,
-		       iint->writecount);
-		iint->writecount = 0;
-	}
-	if (iint->opencount != 0) {
-		printk(KERN_INFO "%s: opencount: %ld\n", __func__,
-		       iint->opencount);
-		iint->opencount = 0;
-	}
-	kref_init(&iint->refcount);
 	kmem_cache_free(iint_cache, iint);
 }
 
-void iint_rcu_free(struct rcu_head *rcu_head)
+/**
+ * ima_inode_alloc - allocate an iint associated with an inode
+ * @inode: pointer to the inode
+ */
+int ima_inode_alloc(struct inode *inode)
 {
-	struct ima_iint_cache *iint = container_of(rcu_head,
-						   struct ima_iint_cache, rcu);
-	kref_put(&iint->refcount, iint_free);
+	struct rb_node **p;
+	struct rb_node *new_node, *parent = NULL;
+	struct ima_iint_cache *new_iint, *test_iint;
+	int rc;
+
+	new_iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
+	if (!new_iint)
+		return -ENOMEM;
+
+	new_iint->inode = inode;
+	new_node = &new_iint->rb_node;
+
+	mutex_lock(&inode->i_mutex); /* i_flags */
+	spin_lock(&ima_iint_lock);
+
+	p = &ima_iint_tree.rb_node;
+	while (*p) {
+		parent = *p;
+		test_iint = rb_entry(parent, struct ima_iint_cache, rb_node);
+
+		rc = -EEXIST;
+		if (inode < test_iint->inode)
+			p = &(*p)->rb_left;
+		else if (inode > test_iint->inode)
+			p = &(*p)->rb_right;
+		else
+			goto out_err;
+	}
+
+	inode->i_flags |= S_IMA;
+	rb_link_node(new_node, parent, p);
+	rb_insert_color(new_node, &ima_iint_tree);
+
+	spin_unlock(&ima_iint_lock);
+	mutex_unlock(&inode->i_mutex); /* i_flags */
+
+	return 0;
+out_err:
+	spin_unlock(&ima_iint_lock);
+	mutex_unlock(&inode->i_mutex); /* i_flags */
+	iint_free(new_iint);
+
+	return rc;
 }
 
 /**
@@ -116,11 +137,20 @@ void ima_inode_free(struct inode *inode)
 {
 	struct ima_iint_cache *iint;
 
+	if (inode->i_readcount)
+		printk(KERN_INFO "%s: readcount: %u\n", __func__, inode->i_readcount);
+
+	inode->i_readcount = 0;
+
+	if (!IS_IMA(inode))
+		return;
+
 	spin_lock(&ima_iint_lock);
-	iint = radix_tree_delete(&ima_iint_store, (unsigned long)inode);
+	iint = __ima_iint_find(inode);
+	rb_erase(&iint->rb_node, &ima_iint_tree);
 	spin_unlock(&ima_iint_lock);
-	if (iint)
-		call_rcu(&iint->rcu, iint_rcu_free);
+
+	iint_free(iint);
 }
 
 static void init_once(void *foo)
@@ -131,10 +161,6 @@ static void init_once(void *foo)
 	iint->version = 0;
 	iint->flags = 0UL;
 	mutex_init(&iint->mutex);
-	iint->readcount = 0;
-	iint->writecount = 0;
-	iint->opencount = 0;
-	kref_init(&iint->refcount);
 }
 
 static int __init ima_iintcache_init(void)
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index e662b89d4079..203de979d305 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -85,50 +85,6 @@ out:
 	return found;
 }
 
-/* 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;
-	}
-}
-
-/*
- * Update the counts given an fmode_t
- */
-static void ima_inc_counts(struct ima_iint_cache *iint, fmode_t mode)
-{
-	BUG_ON(!mutex_is_locked(&iint->mutex));
-
-	iint->opencount++;
-	if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
-		iint->readcount++;
-	if (mode & FMODE_WRITE)
-		iint->writecount++;
-}
-
 /*
  * ima_counts_get - increment file counts
  *
@@ -145,62 +101,101 @@ void ima_counts_get(struct file *file)
 	struct dentry *dentry = file->f_path.dentry;
 	struct inode *inode = dentry->d_inode;
 	fmode_t mode = file->f_mode;
-	struct ima_iint_cache *iint;
 	int rc;
+	bool send_tomtou = false, send_writers = false;
 
-	if (!iint_initialized || !S_ISREG(inode->i_mode))
+	if (!S_ISREG(inode->i_mode))
 		return;
-	iint = ima_iint_find_get(inode);
-	if (!iint)
-		return;
-	mutex_lock(&iint->mutex);
+
+	spin_lock(&inode->i_lock);
+
 	if (!ima_initialized)
 		goto out;
-	rc = ima_must_measure(iint, inode, MAY_READ, FILE_CHECK);
-	if (rc < 0)
-		goto out;
 
 	if (mode & FMODE_WRITE) {
-		ima_read_write_check(TOMTOU, iint, inode, dentry->d_name.name);
+		if (inode->i_readcount && IS_IMA(inode))
+			send_tomtou = true;
 		goto out;
 	}
-	ima_read_write_check(OPEN_WRITERS, iint, inode, dentry->d_name.name);
+
+	rc = ima_must_measure(NULL, inode, MAY_READ, FILE_CHECK);
+	if (rc < 0)
+		goto out;
+
+	if (atomic_read(&inode->i_writecount) > 0)
+		send_writers = true;
 out:
-	ima_inc_counts(iint, file->f_mode);
-	mutex_unlock(&iint->mutex);
+	/* remember the vfs deals with i_writecount */
+	if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
+		inode->i_readcount++;
 
-	kref_put(&iint->refcount, iint_free);
+	spin_unlock(&inode->i_lock);
+
+	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");
 }
 
 /*
  * Decrement ima counts
  */
-static void ima_dec_counts(struct ima_iint_cache *iint, struct inode *inode,
-			   struct file *file)
+static void ima_dec_counts(struct inode *inode, struct file *file)
 {
 	mode_t mode = file->f_mode;
-	BUG_ON(!mutex_is_locked(&iint->mutex));
 
-	iint->opencount--;
-	if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
-		iint->readcount--;
-	if (mode & FMODE_WRITE) {
-		iint->writecount--;
-		if (iint->writecount == 0) {
-			if (iint->version != inode->i_version)
-				iint->flags &= ~IMA_MEASURED;
+	assert_spin_locked(&inode->i_lock);
+
+	if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) {
+		if (unlikely(inode->i_readcount == 0)) {
+			if (!ima_limit_imbalance(file)) {
+				printk(KERN_INFO "%s: open/free imbalance (r:%u)\n",
+				       __func__, inode->i_readcount);
+				dump_stack();
+			}
+			return;
 		}
+		inode->i_readcount--;
 	}
+}
 
-	if (((iint->opencount < 0) ||
-	     (iint->readcount < 0) ||
-	     (iint->writecount < 0)) &&
-	    !ima_limit_imbalance(file)) {
-		printk(KERN_INFO "%s: open/free imbalance (r:%ld w:%ld o:%ld)\n",
-		       __func__, iint->readcount, iint->writecount,
-		       iint->opencount);
-		dump_stack();
-	}
+static void ima_check_last_writer(struct ima_iint_cache *iint,
+				  struct inode *inode,
+				  struct file *file)
+{
+	mode_t mode = file->f_mode;
+
+	BUG_ON(!mutex_is_locked(&iint->mutex));
+	assert_spin_locked(&inode->i_lock);
+
+	if (mode & FMODE_WRITE &&
+	    atomic_read(&inode->i_writecount) == 1 &&
+	    iint->version != inode->i_version)
+		iint->flags &= ~IMA_MEASURED;
+}
+
+static void ima_file_free_iint(struct ima_iint_cache *iint, struct inode *inode,
+			       struct file *file)
+{
+	mutex_lock(&iint->mutex);
+	spin_lock(&inode->i_lock);
+
+	ima_dec_counts(inode, file);
+	ima_check_last_writer(iint, inode, file);
+
+	spin_unlock(&inode->i_lock);
+	mutex_unlock(&iint->mutex);
+}
+
+static void ima_file_free_noiint(struct inode *inode, struct file *file)
+{
+	spin_lock(&inode->i_lock);
+
+	ima_dec_counts(inode, file);
+
+	spin_unlock(&inode->i_lock);
 }
 
 /**
@@ -208,7 +203,7 @@ static void ima_dec_counts(struct ima_iint_cache *iint, struct inode *inode,
  * @file: pointer to file structure being freed
  *
  * Flag files that changed, based on i_version;
- * and decrement the iint readcount/writecount.
+ * and decrement the i_readcount.
  */
 void ima_file_free(struct file *file)
 {
@@ -217,14 +212,14 @@ void ima_file_free(struct file *file)
 
 	if (!iint_initialized || !S_ISREG(inode->i_mode))
 		return;
-	iint = ima_iint_find_get(inode);
-	if (!iint)
-		return;
 
-	mutex_lock(&iint->mutex);
-	ima_dec_counts(iint, inode, file);
-	mutex_unlock(&iint->mutex);
-	kref_put(&iint->refcount, iint_free);
+	iint = ima_iint_find(inode);
+
+	if (iint)
+		ima_file_free_iint(iint, inode, file);
+	else
+		ima_file_free_noiint(inode, file);
+
 }
 
 static int process_measurement(struct file *file, const unsigned char *filename,
@@ -236,11 +231,21 @@ static int process_measurement(struct file *file, const unsigned char *filename,
 
 	if (!ima_initialized || !S_ISREG(inode->i_mode))
 		return 0;
-	iint = ima_iint_find_get(inode);
-	if (!iint)
-		return -ENOMEM;
+
+	rc = ima_must_measure(NULL, inode, mask, function);
+	if (rc != 0)
+		return rc;
+retry:
+	iint = ima_iint_find(inode);
+	if (!iint) {
+		rc = ima_inode_alloc(inode);
+		if (!rc || rc == -EEXIST)
+			goto retry;
+		return rc;
+	}
 
 	mutex_lock(&iint->mutex);
+
 	rc = ima_must_measure(iint, inode, mask, function);
 	if (rc != 0)
 		goto out;
@@ -250,7 +255,6 @@ static int process_measurement(struct file *file, const unsigned char *filename,
 		ima_store_measurement(iint, file, filename);
 out:
 	mutex_unlock(&iint->mutex);
-	kref_put(&iint->refcount, iint_free);
 	return rc;
 }