From: Peter Collingbourne <pcc@google.com>
To: Arnd Bergmann <arnd@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Colin Ian King <colin.king@canonical.com>,
Cong Wang <cong.wang@bytedance.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Networking <netdev@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"# 3.4.x" <stable@vger.kernel.org>
Subject: Re: [PATCH] net: don't unconditionally copy_from_user a struct ifreq for socket ioctls
Date: Thu, 26 Aug 2021 12:46:30 -0700 [thread overview]
Message-ID: <CAMn1gO5Nr_zQ5Sj3yFhSCtFFQfp4jXNU+UPPfCW3_gwfE6c9gA@mail.gmail.com> (raw)
In-Reply-To: <CAK8P3a0Euhxqz50SSid4GmxH1+GWG+weqYS8BLjgxR+ZcC-C=g@mail.gmail.com>
On Thu, Aug 26, 2021 at 1:59 AM Arnd Bergmann <arnd@kernel.org> wrote:
>
> On Thu, Aug 26, 2021 at 3:28 AM Peter Collingbourne <pcc@google.com> wrote:
>
> > - } else {
> > + } else if (is_dev_ioctl_cmd(cmd)) {
> > struct ifreq ifr;
> > bool need_copyout;
> > if (copy_from_user(&ifr, argp, sizeof(struct ifreq)))
> > @@ -1118,6 +1118,8 @@ static long sock_do_ioctl(struct net *net, struct socket *sock,
> > if (!err && need_copyout)
> > if (copy_to_user(argp, &ifr, sizeof(struct ifreq)))
> > return -EFAULT;
> > + } else {
> > + err = -ENOTTY;
> > }
> > return err;
> > }
> > @@ -3306,6 +3308,8 @@ static int compat_ifr_data_ioctl(struct net *net, unsigned int cmd,
> > struct ifreq ifreq;
> > u32 data32;
> >
> > + if (!is_dev_ioctl_cmd(cmd))
> > + return -ENOTTY;
> > if (copy_from_user(ifreq.ifr_name, u_ifreq32->ifr_name, IFNAMSIZ))
> > return -EFAULT;
> > if (get_user(data32, &u_ifreq32->ifr_data))
>
> This adds yet another long switch() statement into the socket ioctl
> case, when there
> is already one in compat_sock_ioctl_trans(), one in dev_ifsioc() and one in
> dev_ioctl(), all with roughly the same set of ioctl command codes. If
I think that David's suggestion of using _IOC_TYPE() should be enough
to address this for now.
> any of them
> are called frequently, that makes it all even slower, so I wonder if
> there should
> be a larger rework altogether. Maybe something based on a single lookup table
> that we search through directly from sock_ioctl()/compat_sock_ioctl() to deal
> with the differences in handling (ifreq based, compat handler, proto_ops
> override, dev_load, rtnl_lock, rcu_read_lock, CAP_NET_ADMIN, copyout, ...).
>
> You are also adding the checks into different places for native and compat
> mode, which makes them diverge more when we should be trying to
> make them more common.
>
> I think based on my recent changes, some other simplifications are possible,
> based on how the compat path already enumerates all the dev ioctls.
I think we should leave that for a followup if still necessary.
Peter
prev parent reply other threads:[~2021-08-26 19:46 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-26 1:27 [PATCH] net: don't unconditionally copy_from_user a struct ifreq for socket ioctls Peter Collingbourne
2021-08-26 6:39 ` Greg KH
2021-08-26 19:46 ` Peter Collingbourne
2021-08-26 8:12 ` David Laight
2021-08-26 19:46 ` Peter Collingbourne
2021-08-27 8:34 ` David Laight
2021-08-26 8:58 ` Arnd Bergmann
2021-08-26 19:46 ` Peter Collingbourne [this message]
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