IMA: remove IMA imbalance checking

Now that i_readcount is maintained by the VFS layer, remove the
imbalance checking in IMA. Cleans up the IMA code nicely.

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>

2 files changed, 4 insertions, 104 deletions

diff --git a/security/integrity/ima/ima_iint.c b/security/integrity/ima/ima_iint.c
index 68efe3b8d993..4ae73040ab7b 100644
--- a/security/integrity/ima/ima_iint.c
+++ b/security/integrity/ima/ima_iint.c
@@ -137,10 +137,6 @@ void ima_inode_free(struct inode *inode)
 {
         struct ima_iint_cache *iint;
 
-        if (atomic_read(&inode->i_readcount))
-                printk(KERN_INFO "%s: readcount: %u\n", __func__,
-                       atomic_read(&inode->i_readcount));
-
         if (!IS_IMA(inode))
                 return;
 
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 69b4856af4da..2df902151193 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -36,55 +36,6 @@ static int __init hash_setup(char *str)
 }
 __setup("ima_hash=", hash_setup);
 
-struct ima_imbalance {
-        struct hlist_node node;
-        unsigned long fsmagic;
-};
-
-/*
- * ima_limit_imbalance - emit one imbalance message per filesystem type
- *
- * Maintain list of filesystem types that do not measure files properly.
- * Return false if unknown, true if known.
- */
-static bool ima_limit_imbalance(struct file *file)
-{
-        static DEFINE_SPINLOCK(ima_imbalance_lock);
-        static HLIST_HEAD(ima_imbalance_list);
-
-        struct super_block *sb = file->f_dentry->d_sb;
-        struct ima_imbalance *entry;
-        struct hlist_node *node;
-        bool found = false;
-
-        rcu_read_lock();
-        hlist_for_each_entry_rcu(entry, node, &ima_imbalance_list, node) {
-                if (entry->fsmagic == sb->s_magic) {
-                        found = true;
-                        break;
-                }
-        }
-        rcu_read_unlock();
-        if (found)
-                goto out;
-
-        entry = kmalloc(sizeof(*entry), GFP_NOFS);
-        if (!entry)
-                goto out;
-        entry->fsmagic = sb->s_magic;
-        spin_lock(&ima_imbalance_lock);
-        /*
-         * we could have raced and something else might have added this fs
-         * to the list, but we don't really care
-         */
-        hlist_add_head_rcu(&entry->node, &ima_imbalance_list);
-        spin_unlock(&ima_imbalance_lock);
-        printk(KERN_INFO "IMA: unmeasured files on fsmagic: %lX\n",
-               entry->fsmagic);
-out:
-        return found;
-}
-
 /*
  * ima_rdwr_violation_check
  *
@@ -131,65 +82,20 @@ out:
                                   "open_writers");
 }
 
-/*
- * Decrement ima counts
- */
-static void ima_dec_counts(struct inode *inode, struct file *file)
-{
-        mode_t mode = file->f_mode;
-
-        assert_spin_locked(&inode->i_lock);
-
-        if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) {
-                if (unlikely(atomic_read(&inode->i_readcount) == 0)) {
-                        if (!ima_limit_imbalance(file)) {
-                                printk(KERN_INFO "%s: open/free imbalance (r:%u)\n",
-                                       __func__,
-                                       atomic_read(&inode->i_readcount));
-                                dump_stack();
-                        }
-                        return;
-                }
-        }
-}
-
 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);
-
+        mutex_lock(&iint->mutex);
         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);
-}
-
 /**
  * ima_file_free - called on __fput()
  * @file: pointer to file structure being freed
@@ -205,12 +111,10 @@ void ima_file_free(struct file *file)
                 return;
 
         iint = ima_iint_find(inode);
+        if (!iint)
+                return;
 
-        if (iint)
-                ima_file_free_iint(iint, inode, file);
-        else
-                ima_file_free_noiint(inode, file);
-
+        ima_check_last_writer(iint, inode, file);
 }
 
 static int process_measurement(struct file *file, const unsigned char *filename,