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

5 files changed, 195 insertions, 177 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;
 }
 
diff --git a/security/security.c b/security/security.c
index b50f472061a4..3ef5e2a7a741 100644
--- a/security/security.c
+++ b/security/security.c
@@ -325,16 +325,8 @@ EXPORT_SYMBOL(security_sb_parse_opts_str);
 
 int security_inode_alloc(struct inode *inode)
 {
-        int ret;
-
         inode->i_security = NULL;
-        ret =  security_ops->inode_alloc_security(inode);
-        if (ret)
-                return ret;
-        ret = ima_inode_alloc(inode);
-        if (ret)
-                security_inode_free(inode);
-        return ret;
+        return security_ops->inode_alloc_security(inode);
 }
 
 void security_inode_free(struct inode *inode)