linux-kernel - Re: [RFC PATCH 2/3] add statmnt(2) syscall

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20230919-gecheckt-loyal-a3355735afef@brauner>
Date:   Tue, 19 Sep 2023 15:18:03 +0200
From:   Christian Brauner <brauner@...nel.org>
To:     Miklos Szeredi <miklos@...redi.hu>
Cc:     Matthew House <mattlloydhouse@...il.com>,
        Miklos Szeredi <mszeredi@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-api@...r.kernel.org, linux-man@...r.kernel.org,
        linux-security-module@...r.kernel.org, Karel Zak <kzak@...hat.com>,
        Ian Kent <raven@...maw.net>,
        David Howells <dhowells@...hat.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <christian@...uner.io>,
        Amir Goldstein <amir73il@...il.com>
Subject: Re: [RFC PATCH 2/3] add statmnt(2) syscall

On Tue, Sep 19, 2023 at 02:59:53PM +0200, Miklos Szeredi wrote:
> On Tue, 19 Sept 2023 at 14:41, Christian Brauner <brauner@...nel.org> wrote:
> >
> > > >  with __u32 size for mnt_root and mnt_point
> > >
> > > Unnecessary if the strings are nul terminated.
> >
> > All ok by me so far but how does the kernel know the size of the buffer
> > to copy into? Wouldn't it be better to allow userspace to specify that?
> > I'm probably just missing something but I better ask.
> 
> Because size of the buffer is given as the syscall argument.
> 
>   long statmount(u64 mnt_id, u64 mask, struct statmnt __user *buf,
> size_t bufsize, unsigned int flags);
> 
> If you are still hung up about this not being properly typed, how about this:

I really just wasn't clear how exactly you envisioned this. Your
proposal as is sounds good to me! I'm on board. I prefer the two offsets
as that lets us avoid searching for null bytes. So please leave it as is!
Thanks!