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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id o128sm1556287pfg.127.2020.07.08.23.35.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Jul 2020 23:35:40 -0700 (PDT) Date: Wed, 8 Jul 2020 23:35:39 -0700 From: Kees Cook To: Christian Brauner Cc: Christoph Hellwig , linux-kernel@vger.kernel.org, Sargun Dhillon , Christian Brauner , Tycho Andersen , David Laight , "David S. Miller" , Jakub Kicinski , Alexander Viro , Aleksa Sarai , Matt Denton , Jann Horn , Chris Palmer , Robert Sesek , Giuseppe Scrivano , Greg Kroah-Hartman , Andy Lutomirski , Will Drewry , Shuah Khan , netdev@vger.kernel.org, containers@lists.linux-foundation.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v6 4/7] pidfd: Replace open-coded partial receive_fd() Message-ID: <202007082330.6B423FE@keescook> References: <20200706201720.3482959-1-keescook@chromium.org> <20200706201720.3482959-5-keescook@chromium.org> <20200707122220.cazzek4655gj4tj7@wittgenstein> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200707122220.cazzek4655gj4tj7@wittgenstein> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 07, 2020 at 02:22:20PM +0200, Christian Brauner wrote: > So while the patch is correct it leaves 5.6 and 5.7 with a bug in the > pidfd_getfd() implementation and that just doesn't seem right. I'm > wondering whether we should introduce: > > void sock_update(struct file *file) > { > struct socket *sock; > int error; > > sock = sock_from_file(file, &error); > if (sock) { > sock_update_netprioidx(&sock->sk->sk_cgrp_data); > sock_update_classid(&sock->sk->sk_cgrp_data); > } > } > > and switch pidfd_getfd() over to: > > diff --git a/kernel/pid.c b/kernel/pid.c > index f1496b757162..c26bba822be3 100644 > --- a/kernel/pid.c > +++ b/kernel/pid.c > @@ -642,10 +642,12 @@ static int pidfd_getfd(struct pid *pid, int fd) > } > > ret = get_unused_fd_flags(O_CLOEXEC); > - if (ret < 0) > + if (ret < 0) { > fput(file); > - else > + } else { > + sock_update(file); > fd_install(ret, file); > + } > > return ret; > } > > first thing in the series and then all of the other patches on top of it > so that we can Cc stable for this and that can get it backported to 5.6, > 5.7, and 5.8. > > Alternatively, I can make this a separate bugfix patch series which I'll > send upstream soonish. Or we have specific patches just for 5.6, 5.7, > and 5.8. Thoughts? Okay, I looked at hch's clean-ups again and I'm reminded why they don't make great -stable material. :) The compat bug (also missing the sock_update()) needs a similar fix (going back to 3.6...), so, yeah, for ease of backport, probably an explicit sock_update() implementation (with compat and native scm using it), and a second patch for pidfd. Let me see what I looks best... -- Kees Cook