From 1ca551c6caae7b52178555cdedea6ca26444be46 Mon Sep 17 00:00:00 2001 From: Marco Stornelli Date: Sat, 5 Mar 2011 11:10:19 +0100 Subject: [PATCH] Check for immutable/append flag in fallocate path 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 Signed-off-by: Al Viro --- fs/open.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/fs/open.c b/fs/open.c index 5a2c6ebc22b5..b47aab39c057 100644 --- a/fs/open.c +++ b/fs/open.c @@ -233,6 +233,14 @@ int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len) 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. -- 2.20.1