linux-kernel - [86/93] eCryptfs: Add getattr function

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Date:	Fri, 19 Feb 2010 08:30:19 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Tyler Hicks <tyhicks@...ux.vnet.ibm.com>,
	Tim Gardner <timg@....com>
Subject: [86/93] eCryptfs: Add getattr function

2.6.32-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Tyler Hicks <tyhicks@...ux.vnet.ibm.com>

commit f8f484d1b6677dd5cd5e7e605db747e8c30bbd47 upstream.

The i_blocks field of an eCryptfs inode cannot be trusted, but
generic_fillattr() uses it to instantiate the blocks field of a stat()
syscall when a filesystem doesn't implement its own getattr().  Users
have noticed that the output of du is incorrect on newly created files.

This patch creates ecryptfs_getattr() which calls into the lower
filesystem's getattr() so that eCryptfs can use its kstat.blocks value
after calling generic_fillattr().  It is important to note that the
block count includes the eCryptfs metadata stored in the beginning of
the lower file plus any padding used to fill an extent before
encryption.

https://bugs.launchpad.net/ecryptfs/+bug/390833

Reported-by: Dominic Sacré <dominic.sacre@....de>
Signed-off-by: Tyler Hicks <tyhicks@...ux.vnet.ibm.com>
Cc: Tim Gardner <timg@....com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 fs/ecryptfs/inode.c |   16 ++++++++++++++++
 1 file changed, 16 insertions(+)

--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -971,6 +971,21 @@ out:
 	return rc;
 }
 
+int ecryptfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
+		     struct kstat *stat)
+{
+	struct kstat lower_stat;
+	int rc;
+
+	rc = vfs_getattr(ecryptfs_dentry_to_lower_mnt(dentry),
+			 ecryptfs_dentry_to_lower(dentry), &lower_stat);
+	if (!rc) {
+		generic_fillattr(dentry->d_inode, stat);
+		stat->blocks = lower_stat.blocks;
+	}
+	return rc;
+}
+
 int
 ecryptfs_setxattr(struct dentry *dentry, const char *name, const void *value,
 		  size_t size, int flags)
@@ -1100,6 +1115,7 @@ const struct inode_operations ecryptfs_d
 const struct inode_operations ecryptfs_main_iops = {
 	.permission = ecryptfs_permission,
 	.setattr = ecryptfs_setattr,
+	.getattr = ecryptfs_getattr,
 	.setxattr = ecryptfs_setxattr,
 	.getxattr = ecryptfs_getxattr,
 	.listxattr = ecryptfs_listxattr,


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