From: Marco Stornelli <marco.stornelli@xxxxxxxxx> 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@xxxxxxxxx> --- 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. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
