IMA: move read counter into struct inode

IMA currently allocated an inode integrity structure for every inode in
core.  This stucture is about 120 bytes long.  Most files however
(especially on a system which doesn't make use of IMA) will never need
any of this space.  The problem is that if IMA is enabled we need to
know information about the number of readers and the number of writers
for every inode on the box.  At the moment we collect that information
in the per inode iint structure and waste the rest of the space.  This
patch moves those counters into the struct inode so we can eventually
stop allocating an IMA integrity structure except when absolutely
needed.

This patch does the minimum needed to move the location of the data.
Further cleanups, especially the location of counter updates, may still
be possible.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 25 deletions

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 24660bf3f82a..2a77b14fee27 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -86,17 +86,6 @@ out:
 }
 
 /*
- * Update the counts given an fmode_t
- */
-static void ima_inc_counts(struct ima_iint_cache *iint, fmode_t mode)
-{
-        assert_spin_locked(&iint->inode->i_lock);
-
-        if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
-                iint->readcount++;
-}
-
-/*
  * ima_counts_get - increment file counts
  *
  * Maintain read/write counters for all files, but only
@@ -112,27 +101,23 @@ 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);
+        rc = ima_must_measure(NULL, inode, MAY_READ, FILE_CHECK);
         if (rc < 0)
                 goto out;
 
         if (mode & FMODE_WRITE) {
-                if (iint->readcount)
+                if (inode->i_readcount)
                         send_tomtou = true;
                 goto out;
         }
@@ -140,10 +125,10 @@ void ima_counts_get(struct file *file)
         if (atomic_read(&inode->i_writecount) > 0)
                 send_writers = true;
 out:
-        ima_inc_counts(iint, file->f_mode);
+        /* remember the vfs deals with i_writecount */
+        if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
+                inode->i_readcount++;
         spin_unlock(&inode->i_lock);
-        mutex_unlock(&iint->mutex);
-        kref_put(&iint->refcount, iint_free);
 
         if (send_tomtou)
                 ima_add_violation(inode, dentry->d_name.name, "invalid_pcr",
@@ -166,9 +151,9 @@ static void ima_dec_counts(struct ima_iint_cache *iint, struct inode *inode,
         assert_spin_locked(&inode->i_lock);
 
         if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) {
-                if (unlikely(iint->readcount == 0))
+                if (unlikely(inode->i_readcount == 0))
                         dump = true;
-                iint->readcount--;
+                inode->i_readcount--;
         }
         if (mode & FMODE_WRITE) {
                 if (atomic_read(&inode->i_writecount) <= 0)
@@ -180,7 +165,7 @@ static void ima_dec_counts(struct ima_iint_cache *iint, struct inode *inode,
 
         if (dump && !ima_limit_imbalance(file)) {
                 printk(KERN_INFO "%s: open/free imbalance (r:%u)\n",
-                       __func__, iint->readcount);
+                       __func__, inode->i_readcount);
                 dump_stack();
         }
 }