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>

diff --git a/fs/inode.c b/fs/inode.c
index 86464332e590dfdc9cbf041515f038f0de1d846d..56d909d69bc88cda72bb70a528fbf0c70e877d0d 100644 (file)
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -24,6 +24,7 @@
 #include <linux/mount.h>
 #include <linux/async.h>
 #include <linux/posix_acl.h>
+#include <linux/ima.h>
 
 /*
  * This is needed for the following functions:

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 63d069bd80b702c392d4052bf2be937f90763692..01e3a0047fed244b2ee4e71712a562b035f99ee7 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -776,6 +776,10 @@ struct inode {
 
        unsigned int            i_flags;
 
+#ifdef CONFIG_IMA
+       /* protected by i_lock */
+       unsigned int            i_readcount; /* struct files open RO */
+#endif
        atomic_t                i_writecount;
 #ifdef CONFIG_SECURITY
        void                    *i_security;

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index b546b90f5fa874a6be1bbfad9ef47f029735c053..27849e1656dc25ffc6391c903e7133e3c05794fe 100644 (file)
--- 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);
@@ -106,8 +107,6 @@ struct ima_iint_cache {
        unsigned char flags;
        u8 digest[IMA_DIGEST_SIZE];
        struct mutex mutex;     /* protects: version, flags, digest */
-       /* protected by inode->i_lock */
-       unsigned int readcount; /* measured files readcount */
        struct kref refcount;   /* ima_iint_cache reference count */
 };
 

diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 52015d098fdfd6d1823cf44ccfef1e754605884f..d3963de6003da423c26cc1028258fe70fd1cf1b3 100644 (file)
--- 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 e68891f8d55afe1aadca81885e499c57643b469c..0936a7197e477b6eaaa5fb4ac87439009b686b62 100644 (file)
--- a/security/integrity/ima/ima_iint.c
+++ b/security/integrity/ima/ima_iint.c
@@ -124,11 +124,6 @@ void iint_free(struct kref *kref)
                                                   refcount);
        iint->version = 0;
        iint->flags = 0UL;
-       if (iint->readcount != 0) {
-               printk(KERN_INFO "%s: readcount: %u\n", __func__,
-                      iint->readcount);
-               iint->readcount = 0;
-       }
        kref_init(&iint->refcount);
        kmem_cache_free(iint_cache, iint);
 }
@@ -143,6 +138,11 @@ 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;
+
        spin_lock(&ima_iint_lock);
        iint = __ima_iint_find(inode);
        if (iint)
@@ -160,7 +160,6 @@ static void init_once(void *foo)
        iint->version = 0;
        iint->flags = 0UL;
        mutex_init(&iint->mutex);
-       iint->readcount = 0;
        kref_init(&iint->refcount);
 }
 

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 24660bf3f82ab27a22de12a551961e84772738bc..2a77b14fee27cf11327aa8581112fa11a30a0bc0 100644 (file)
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -85,17 +85,6 @@ out:
        return found;
 }
 
-/*
- * 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
  *
@@ -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();
        }
 }