From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Biggers Date: Wed, 23 May 2018 21:17:09 +0000 Subject: Re: [PATCH] ppp: remove the PPPIOCDETACH ioctl Message-Id: <20180523211709.GA63112@gmail.com> List-Id: References: <20180523032958.GE658@sol.localdomain> <20180523035952.25768-1-ebiggers3@gmail.com> <20180523135708.GB1569@alphalink.fr> <20180523.115636.2241611659399097483.davem@davemloft.net> In-Reply-To: <20180523.115636.2241611659399097483.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: David Miller Cc: g.nault@alphalink.fr, linux-ppp@vger.kernel.org, paulus@samba.org, netdev@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, ebiggers@google.com On Wed, May 23, 2018 at 11:56:36AM -0400, David Miller wrote: > From: Guillaume Nault > Date: Wed, 23 May 2018 15:57:08 +0200 > > > I'd rather add > > + if (cmd = PPPIOCDETACH) { > > + err = -EINVAL; > > + goto out; > > + } > > > > Making PPPIOCDETACH unknown to ppp_generic means that the ioctl would > > be handled by the underlying channel when pf->kind = CHANNEL (see the > > chan->ops->ioctl() call further down). That shouldn't be a problem per > > se, but even though PPPIOCDETACH is unsupported, I feel that it should > > remain a ppp_generic thing. I don't really want its value to be reused > > for other purposes in the future or have different behaviour depending > > on the underlying channel. > > > > Also PPPIOCDETACH can already fail with -EINVAL. Therefore, if ever > > there really were programs out there using this call, they'd already > > have to handle this case. Unconditionally returning -EINVAL would > > further minimise possibilities for breakage. > > I agree. Okay, I'll do that and leave the ioctl number reserved. I will add a pr_warn_once() too. Thanks, - Eric