linux-kernel - Re: [RFC/PATCH] revoke/frevoke system calls

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 for Android: free password hash cracker in your pocket

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

Message-Id: <20060721235931.e8336001.akpm@osdl.org>
Date:	Fri, 21 Jul 2006 23:59:31 -0700
From:	Andrew Morton <akpm@...l.org>
To:	Pekka J Enberg <penberg@...Helsinki.FI>
Cc:	alan@...rguk.ukuu.org.uk, tytso@....edu,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [RFC/PATCH] revoke/frevoke system calls

On Sat, 22 Jul 2006 09:22:37 +0300 (EEST)
Pekka J Enberg <penberg@...Helsinki.FI> wrote:

> On Thu, 20 Jul 2006 15:07:30 +0300 (EEST)
> Pekka J Enberg <penberg@...Helsinki.FI> wrote:
> > > This patch implements the revoke(2) and frevoke(2) system calls for all
> > > types of files.
> > >
> > > ...
> > >
> > > -	file = fget_light(fd, &fput_needed);
> > > +	file = fget(fd);
>  
> On Fri, 21 Jul 2006, Andrew Morton wrote:
> > This is sad.
> 
> There are alternatives, playing games with ->f_op, creating fake struct 
> file, and doing IS_REVOKED if-else in the paths, but I think this is by 
> far the simplest way to do it. So in the Andrew scale of sads, how 
> sad is it, exactly?-)

Sad enough.  Certainly worth an if-else to fix.

> On Thu, 20 Jul 2006 15:07:30 +0300 (EEST)
> Pekka J Enberg <penberg@...Helsinki.FI> wrote:
> > > +static int revoke_files(struct task_struct *owner, struct inode *inode,
> > > +			struct file *exclude, struct list_head *to_close)
> > > +{
> > > ...
> > > +	spin_lock(&files->file_lock);
> > > ...
> > > +		revoked = kmalloc(sizeof(*revoked), GFP_KERNEL);
>  
> On Fri, 21 Jul 2006, Andrew Morton wrote:
> > This is bad.
> 
> Indeed, I'll come up with a better one as soon as I sort out the mmap 
> takedown issues.
> 

Why is this approach so different from Tigran's, I wonder.

iirc, one of the things we added file.f_mapping for was revokation, but
this patch doesn't use it.  Please ask Al Viro about this.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/