From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 54A5BC433F5 for ; Thu, 4 Nov 2021 01:46:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 33F68611ED for ; Thu, 4 Nov 2021 01:46:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231945AbhKDBtX (ORCPT ); Wed, 3 Nov 2021 21:49:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42488 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231206AbhKDBtW (ORCPT ); Wed, 3 Nov 2021 21:49:22 -0400 Received: from mail-wr1-x435.google.com (mail-wr1-x435.google.com [IPv6:2a00:1450:4864:20::435]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7F298C061714; Wed, 3 Nov 2021 18:46:45 -0700 (PDT) Received: by mail-wr1-x435.google.com with SMTP id i5so6267608wrb.2; Wed, 03 Nov 2021 18:46:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=6UZ9QzgDO0cKHF5YhLIs9VgxnGlTbz4OFbftB+dyTWA=; b=eOctDe7zw0mVyaLMEPaq0CFWmR4LZfppwf58NICJVQVHgxHuAybDgae0VUPRcoeOMv wjZjTw4bYaczAzL8k+U+B4l/WwCWdxGz7KStaJcBEh9xOy8kJYu4is6Rsg17KY3DT82q jYzkWEFyoimN2aBMEBVMaJofUFRb0TBXHLzpLzCWC/9+4LggC/v1lpQGi4gMUgqwNn0A zFuN6/qKcq1gr6C+3turAL4FJAekc53LdQpSW3iXXmZtxDKHCkGV84oEJbEHrhP/ii1f qtd0ej6TAGnm6jzfQQKgfLQgWDXHtFjsZ+mktSCK4FnbVs9tQ2UwPGOHCN2ZufDQKcjU 6JxA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=6UZ9QzgDO0cKHF5YhLIs9VgxnGlTbz4OFbftB+dyTWA=; b=NQ5sAqJ5r2roScbGZXcNjLusEwD1Sqtdq+pFYctCScNxailsJJc0c0OBmooRpp1hb4 GkI94rx2gWw0dYS4KyYGl6xqTsnRxi4bVYWH57hW39m7/wgcCPpHqQadj+JKT4/I6hgQ m096o9jMsr/k/gVCMVxYjOQYKZsRJHC87Goz/O+1Akv9W/tvWjK+goRHXp9reuf5Cd8C R4l3lEPd8vkPMZ/uvhS6WKLmvIOQsNuhtzq6Fz9fgKOX06bad8t4b1XQPSAr5JzAhdot n4Ha68/Q4MCWHWO+xOLzriZBbZyEJnIkVknhNEp5DdbkJ34sgBuVX7qDHsbOA55lvSpg +9NQ== X-Gm-Message-State: AOAM533SJluZqmkx2ocfvy9bU06fmUZ51gYPpw9TcrdyAmiPCL2fgYHV fJZ//1zTqDvsj9crmp8eqzReXZGH2Zvdys0vBsw= X-Google-Smtp-Source: ABdhPJyaczO54g3EhWm66dK0ow4tFDvuAAcvmMZ/5PYaCARB8LDFdfh3ulyit0H+xLHFBkeZeVgk7T4IWFENx42QB6I= X-Received: by 2002:a5d:4563:: with SMTP id a3mr43479496wrc.130.1635990404084; Wed, 03 Nov 2021 18:46:44 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Xin Long Date: Wed, 3 Nov 2021 21:46:32 -0400 Message-ID: Subject: Re: [PATCHv2 net 4/4] security: implement sctp_assoc_established hook in selinux To: Paul Moore Cc: Ondrej Mosnacek , network dev , SElinux list , Linux Security Module list , "linux-sctp @ vger . kernel . org" , "David S. Miller" , Jakub Kicinski , Marcelo Ricardo Leitner , James Morris , Richard Haines Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: On Wed, Nov 3, 2021 at 6:01 PM Paul Moore wrote: > > On Wed, Nov 3, 2021 at 1:36 PM Xin Long wrote: > > On Wed, Nov 3, 2021 at 1:33 PM Xin Long wrote: > > > On Wed, Nov 3, 2021 at 12:40 PM Ondrej Mosnacek wrote: > > > > On Tue, Nov 2, 2021 at 1:03 PM Xin Long wrote: > > > > > > > > > > Different from selinux_inet_conn_established(), it also gives the > > > > > secid to asoc->peer_secid in selinux_sctp_assoc_established(), > > > > > as one UDP-type socket may have more than one asocs. > > > > > > > > > > Note that peer_secid in asoc will save the peer secid for this > > > > > asoc connection, and peer_sid in sksec will just keep the peer > > > > > secid for the latest connection. So the right use should be do > > > > > peeloff for UDP-type socket if there will be multiple asocs in > > > > > one socket, so that the peeloff socket has the right label for > > > > > its asoc. > > > > > > > > > > v1->v2: > > > > > - call selinux_inet_conn_established() to reduce some code > > > > > duplication in selinux_sctp_assoc_established(), as Ondrej > > > > > suggested. > > > > > - when doing peeloff, it calls sock_create() where it actually > > > > > gets secid for socket from socket_sockcreate_sid(). So reuse > > > > > SECSID_WILD to ensure the peeloff socket keeps using that > > > > > secid after calling selinux_sctp_sk_clone() for client side. > > > > > > > > Interesting... I find strange that SCTP creates the peeloff socket > > > > using sock_create() rather than allocating it directly via > > > > sock_alloc() like the other callers of sctp_copy_sock() (which calls > > > > security_sctp_sk_clone()) do. Wouldn't it make more sense to avoid the > > > > sock_create() call and just rely on the security_sctp_sk_clone() > > > > semantic to set up the labels? Would anything break if > > > > sctp_do_peeloff() switched to plain sock_alloc()? > > > > > > > > I'd rather we avoid this SECSID_WILD hack to support the weird > > > > created-but-also-cloned socket hybrid and just make the peeloff socket > > > > behave the same as an accept()-ed socket (i.e. no > > > > security_socket_[post_]create() hook calls, just > > > > security_sctp_sk_clone()). > > I believe the important part is that sctp_do_peeloff() eventually > calls security_sctp_sk_clone() via way of sctp_copy_sock(). Assuming > we have security_sctp_sk_clone() working properly I would expect that > the new socket would be setup properly when sctp_do_peeloff() returns > on success. > > ... and yes, that SECSID_WILD approach is *not* something we want to do. SECSID_WILD is used to avoid client's new socket's sid overwritten by old socket's. If I understand correctly, new socket's should keep using its original sid, namely, the one set from security_socket_[post_]create() on client side. I AGREE with that. Now I want to *confirm* this with you, as it's different from the last version's 'inherit from parent socket' that Richard and Ondrej reviewed. > > In my mind, selinux_sctp_sk_clone() should end up looking like this. > > void selinux_sctp_sk_clone(asoc, sk, newsk) > { > struct sk_security_struct sksec = sk->sk_security; > struct sk_security_struct newsksec = newsk->sk_security; > > if (!selinux_policycap_extsockclass()) > return selinux_sk_clone_security(sk, newsk); > > newsksec->sid = sksec->secid; > newsksec->peer_sid = asoc->peer_secid; > newsksec->sclass = sksec->sclass; > selinux_netlbl_sctp_sk_clone(sk, newsk); > } Let's say, this socket has 3 associations now, how can we ensure the new socket's sid is set to the right sid? I don't think we can use "sksec->secid" in this place, this is not TCP. > > Also, to be clear, the "assoc->secid = SECSID_WILD;" line should be > removed from selinux_sctp_assoc_established(). If we are treating > SCTP associations similarly to TCP connections, the association's > label/secid should be set once and not changed during the life of the > association. The association's label/secid will never change once set in this patchset. it's just a temporary record, and later it will be used to set socket's label/secid. I think that's the idea at the beginning. > > > > > > Fixes: 72e89f50084c ("security: Add support for SCTP security hooks") > > > > > Reported-by: Prashanth Prahlad > > > > > Reviewed-by: Richard Haines > > > > > Tested-by: Richard Haines > > > > > > > > You made non-trivial changes since the last revision in this patch, so > > > > you should have also dropped the Reviewed-by and Tested-by here. Now > > > > David has merged the patches probably under the impression that they > > > > have been reviewed/approved from the SELinux side, which isn't > > > > completely true. > > > > > > Oh, that's a mistake, I thought I didn't add it. > > > Will he be able to test this new patchset? > > While I tend to try to avoid reverts as much as possible, I think the > right thing to do is to get these patches reverted out of DaveM's tree > while we continue to sort this out and do all of the necessary testing > and verification. > > Xin Long, please work with the netdev folks to get your patchset > reverted and then respin this patchset using the feedback provided. Hi, Paul, The original issue this patchset fixes is a crucial one (it could cause peeloff sockets on client side to not work) which I think can already be fixed now. If you think SECSID_WILD is tricky but no better way yet, my suggestion is to leave it for now until we have a better solution to follow up. As I couldn't find a better way to work it out. Also, we may want to hear Richard's opinion on how it should work and how this should be fixed. Thanks. > > -- > paul moore > www.paul-moore.com