linux-ext4 - [patch] ext4 defrag executables

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Message-ID: <4C7AB963.6030401@rid-net.de>
Date:	Sun, 29 Aug 2010 21:47:47 +0200
From:	Andreas Rid <andreas@...-net.de>
To:	tytso@....edu
CC:	linux-ext4@...r.kernel.org
Subject: [patch] ext4 defrag executables

hi,

since ioctl EXT4_IOC_MOVE_EXT checks the original file descriptor for write access it's no longer possible to defrag executable files which are currently in use. This is because you can only open() those files readonly.
This patch solves it without adding a security hole. 
What do you think about it?

 Andreas


diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 352cb35..ae45380 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -242,8 +242,8 @@ setversion_out:
 		struct file *donor_filp;
 		int err;
 
-		if (!(filp->f_mode & FMODE_READ) ||
-		    !(filp->f_mode & FMODE_WRITE))
+		if (generic_permission(filp->f_dentry->d_inode,
+			MAY_READ | MAY_WRITE, NULL))
 			return -EBADF;
 
 		if (copy_from_user(&me,
--
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