vfs: increment iversion when a file is truncated

When a file is truncated with truncate()/ftruncate() and then closed,
iversion is not updated.  This patch uses ATTR_SIZE flag as an indication
to increment iversion.

Mimi said:

On fput(), i_version is used to detect and flag files that have changed
and need to be re-measured in the IMA measurement policy.  When a file
is truncated with truncate()/ftruncate() and then closed, i_version is
not updated.  As a result, although the file has changed, it will not be
re-measured and added to the IMA measurement list on subsequent access.

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Acked-by: Mimi Zohar <zohar@us.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/attr.c b/fs/attr.c
index cce7df53b694373b6288795f14b07eb91c0894fc..9689817dd26a490b5b9424c2058bb2f879cc6a13 100644 (file)
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -184,6 +184,11 @@ int notify_change(struct dentry * dentry, struct iattr * attr)
                        inode_inc_iversion(inode);
        }
 
+       if ((ia_valid & ATTR_SIZE) && IS_I_VERSION(inode)) {
+               if (attr->ia_size != inode->i_size)
+                       inode_inc_iversion(inode);
+       }
+
        if ((ia_valid & ATTR_MODE)) {
                umode_t amode = attr->ia_mode;
                /* Flag setting protected by i_mutex */