[PATCH 1/3] disallow seeks and appends on sysfs files

[Mitch Williams]

This patch causes sysfs to return errors if the caller attempts to append
to or seek on a sysfs file.

Generated from 2.6.11-rc1.

Signed-off-by: Mitch Williams <mitch.a.williams@xxxxxxxxx>

diff -uprN -X dontdiff linux-2.6.11-clean/fs/sysfs/file.c linux-2.6.11/fs/sysfs/file.c
--- linux-2.6.11-clean/fs/sysfs/file.c	2004-12-24 13:33:50.000000000 -0800
+++ linux-2.6.11/fs/sysfs/file.c	2005-01-21 13:09:21.000000000 -0800
@@ -281,6 +281,11 @@ static int check_perm(struct inode * ino
 	if (!ops)
 		goto Eaccess;

+	/* Is the file is open for append?  Sorry, we don't do that. */
+	if (file->f_flags & O_APPEND) {
+		goto Einval;
+	}
+
 	/* File needs write support.
 	 * The inode's perms must say it's ok,
 	 * and we must have a store method.
@@ -312,6 +302,10 @@ static int check_perm(struct inode * ino
 		file->private_data = buffer;
 	} else
 		error = -ENOMEM;
+
+	/*  Set mode bits to disallow seeking.  */
+	file->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
+
 	goto Done;

  Einval:
@@ -368,7 +343,7 @@ static int sysfs_release(struct inode *
 struct file_operations sysfs_file_operations = {
 	.read		= sysfs_read_file,
 	.write		= sysfs_write_file,
-	.llseek		= generic_file_llseek,
+	.llseek		= no_llseek,
 	.open		= sysfs_open_file,
 	.release	= sysfs_release,
 };
-
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