lkml.org 
[lkml]   [2011]   [Mar]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH v3] Check for immutable/append flag in fallocate path
From: Marco Stornelli <marco.stornelli@gmail.com>

In the fallocate path the kernel doesn't check for the immutable/append
flag. It's possible to have a race condition in this scenario: an
application open a file in read/write and it does something, meanwhile
root set the immutable flag on the file, the application at that point
can call fallocate with success. In addition, we don't allow to do any
unreserve operation on an append only file but only the reserve one.

Signed-off-by: Marco Stornelli <marco.stornelli@gmail.com>
---
Patch is against 2.6.38-rc7

ChangeLog:
v3: Modified do_fallocate instead of every single fs
v2: Added the check for append-only file for XFS
v1: First draft

--- open.c.orig 2011-03-01 22:55:12.000000000 +0100
+++ open.c 2011-03-04 15:28:43.000000000 +0100
@@ -233,6 +233,14 @@ int do_fallocate(struct file *file, int

if (!(file->f_mode & FMODE_WRITE))
return -EBADF;
+
+ /* It's not possible punch hole on append only file */
+ if (mode & FALLOC_FL_PUNCH_HOLE && IS_APPEND(inode))
+ return -EPERM;
+
+ if (IS_IMMUTABLE(inode))
+ return -EPERM;
+
/*
* Revalidate the write permissions, in case security policy has
* changed since the files were opened.


\
 
 \ /
  Last update: 2011-03-06 11:17    [W:0.153 / U:0.084 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site