From: Paul Moore <paul@paul-moore.com> To: Daniel Borkmann <daniel@iogearbox.net> Cc: Ondrej Mosnacek <omosnace@redhat.com>, Linux Security Module list <linux-security-module@vger.kernel.org>, James Morris <jmorris@namei.org>, Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@redhat.com>, Stephen Smalley <stephen.smalley.work@gmail.com>, SElinux list <selinux@vger.kernel.org>, linuxppc-dev@lists.ozlabs.org, Linux FS Devel <linux-fsdevel@vger.kernel.org>, bpf <bpf@vger.kernel.org>, network dev <netdev@vger.kernel.org>, Linux kernel mailing list <linux-kernel@vger.kernel.org>, Casey Schaufler <casey@schaufler-ca.com>, Jiri Olsa <jolsa@redhat.com>, andrii.nakryiko@gmail.com Subject: Re: [PATCH v2] lockdown,selinux: avoid bogus SELinux lockdown permission checks Date: Fri, 28 May 2021 11:54:05 -0400 [thread overview] Message-ID: <CAHC9VhTuurjpkgq=cS5ZNwpxuuOq4E3eE2RuD+JaCQz6X0fk6g@mail.gmail.com> (raw) In-Reply-To: <17eaebd3-6389-8c80-38ed-dada9d087266@iogearbox.net> On Fri, May 28, 2021 at 10:43 AM Daniel Borkmann <daniel@iogearbox.net> wrote: > On 5/28/21 3:42 PM, Ondrej Mosnacek wrote: > > (I'm off work today and plan to reply also to Paul's comments next > > week, but for now let me at least share a couple quick thoughts on > > Daniel's patch.) Oooh, I sense some disagreement brewing :) > > On Fri, May 28, 2021 at 11:56 AM Daniel Borkmann <daniel@iogearbox.net> wrote: > >> On 5/28/21 9:09 AM, Daniel Borkmann wrote: > >>> On 5/28/21 3:37 AM, Paul Moore wrote: > >>>> On Mon, May 17, 2021 at 5:22 AM Ondrej Mosnacek <omosnace@redhat.com> wrote: ... > >> Ondrej / Paul / Jiri: at least for the BPF tracing case specifically (I haven't looked > >> at the rest but it's also kind of independent), the attached fix should address both > >> reported issues, please take a look & test. > > > > Thanks, I like this solution, although there are a few gotchas: > > > > 1. This patch creates a slight "regression" in that if someone flips > > the Lockdown LSM into lockdown mode on runtime, existing (already > > loaded) BPF programs will still be able to call the > > confidentiality-breaching helpers, while before the lockdown would > > apply also to them. Personally, I don't think it's a big deal (and I > > bet there are other existing cases where some handle kept from before > > lockdown could leak data), but I wanted to mention it in case someone > > thinks the opposite. > > Yes, right, though this is nothing new either in the sense that there are > plenty of other cases with security_locked_down() that operate this way > e.g. take the open_kcore() for /proc/kcore access or the module_sig_check() > for mod signatures just to pick some random ones, same approach where the > enforcement is happen at open/load time. Another, yes, this is not really a good thing to do. Also, just because there are other places that don't really do The Right Thing doesn't mean that it is okay to also not do The Right Thing here. It's basically the two-wrongs-don't-make-a-right issue applied to kernel code. -- paul moore www.paul-moore.com
WARNING: multiple messages have this Message-ID (diff)
From: Paul Moore <paul@paul-moore.com> To: Daniel Borkmann <daniel@iogearbox.net> Cc: Jiri Olsa <jolsa@redhat.com>, SElinux list <selinux@vger.kernel.org>, network dev <netdev@vger.kernel.org>, Stephen Smalley <stephen.smalley.work@gmail.com>, Ondrej Mosnacek <omosnace@redhat.com>, Steven Rostedt <rostedt@goodmis.org>, James Morris <jmorris@namei.org>, Casey Schaufler <casey@schaufler-ca.com>, Linux Security Module list <linux-security-module@vger.kernel.org>, Ingo Molnar <mingo@redhat.com>, Linux FS Devel <linux-fsdevel@vger.kernel.org>, bpf <bpf@vger.kernel.org>, andrii.nakryiko@gmail.com, linuxppc-dev@lists.ozlabs.org, Linux kernel mailing list <linux-kernel@vger.kernel.org> Subject: Re: [PATCH v2] lockdown,selinux: avoid bogus SELinux lockdown permission checks Date: Fri, 28 May 2021 11:54:05 -0400 [thread overview] Message-ID: <CAHC9VhTuurjpkgq=cS5ZNwpxuuOq4E3eE2RuD+JaCQz6X0fk6g@mail.gmail.com> (raw) In-Reply-To: <17eaebd3-6389-8c80-38ed-dada9d087266@iogearbox.net> On Fri, May 28, 2021 at 10:43 AM Daniel Borkmann <daniel@iogearbox.net> wrote: > On 5/28/21 3:42 PM, Ondrej Mosnacek wrote: > > (I'm off work today and plan to reply also to Paul's comments next > > week, but for now let me at least share a couple quick thoughts on > > Daniel's patch.) Oooh, I sense some disagreement brewing :) > > On Fri, May 28, 2021 at 11:56 AM Daniel Borkmann <daniel@iogearbox.net> wrote: > >> On 5/28/21 9:09 AM, Daniel Borkmann wrote: > >>> On 5/28/21 3:37 AM, Paul Moore wrote: > >>>> On Mon, May 17, 2021 at 5:22 AM Ondrej Mosnacek <omosnace@redhat.com> wrote: ... > >> Ondrej / Paul / Jiri: at least for the BPF tracing case specifically (I haven't looked > >> at the rest but it's also kind of independent), the attached fix should address both > >> reported issues, please take a look & test. > > > > Thanks, I like this solution, although there are a few gotchas: > > > > 1. This patch creates a slight "regression" in that if someone flips > > the Lockdown LSM into lockdown mode on runtime, existing (already > > loaded) BPF programs will still be able to call the > > confidentiality-breaching helpers, while before the lockdown would > > apply also to them. Personally, I don't think it's a big deal (and I > > bet there are other existing cases where some handle kept from before > > lockdown could leak data), but I wanted to mention it in case someone > > thinks the opposite. > > Yes, right, though this is nothing new either in the sense that there are > plenty of other cases with security_locked_down() that operate this way > e.g. take the open_kcore() for /proc/kcore access or the module_sig_check() > for mod signatures just to pick some random ones, same approach where the > enforcement is happen at open/load time. Another, yes, this is not really a good thing to do. Also, just because there are other places that don't really do The Right Thing doesn't mean that it is okay to also not do The Right Thing here. It's basically the two-wrongs-don't-make-a-right issue applied to kernel code. -- paul moore www.paul-moore.com
next prev parent reply other threads:[~2021-05-28 15:54 UTC|newest] Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-05-17 9:20 [PATCH v2] lockdown,selinux: avoid bogus SELinux lockdown permission checks Ondrej Mosnacek 2021-05-17 9:20 ` [PATCH v2] lockdown, selinux: " Ondrej Mosnacek 2021-05-17 11:00 ` [PATCH v2] lockdown,selinux: " Michael Ellerman 2021-05-17 11:00 ` Michael Ellerman 2021-05-26 11:44 ` Ondrej Mosnacek 2021-05-26 11:44 ` Ondrej Mosnacek 2021-05-27 4:28 ` James Morris 2021-05-27 4:28 ` James Morris 2021-05-27 14:18 ` Paul Moore 2021-05-27 14:18 ` Paul Moore 2021-05-28 1:37 ` Paul Moore 2021-05-28 1:37 ` Paul Moore 2021-05-28 7:09 ` Daniel Borkmann 2021-05-28 7:09 ` Daniel Borkmann 2021-05-28 9:53 ` Jiri Olsa 2021-05-28 9:53 ` Jiri Olsa 2021-05-28 9:56 ` Daniel Borkmann 2021-05-28 9:56 ` Daniel Borkmann 2021-05-28 10:16 ` Jiri Olsa 2021-05-28 10:16 ` Jiri Olsa 2021-05-28 11:47 ` Jiri Olsa 2021-05-28 11:47 ` Jiri Olsa 2021-05-28 11:54 ` Daniel Borkmann 2021-05-28 11:54 ` Daniel Borkmann 2021-05-28 13:42 ` Ondrej Mosnacek 2021-05-28 13:42 ` Ondrej Mosnacek 2021-05-28 14:20 ` Daniel Borkmann 2021-05-28 14:20 ` Daniel Borkmann 2021-05-28 15:54 ` Paul Moore [this message] 2021-05-28 15:54 ` Paul Moore 2021-05-28 15:47 ` Paul Moore 2021-05-28 15:47 ` Paul Moore 2021-05-28 18:10 ` Daniel Borkmann 2021-05-28 18:10 ` Daniel Borkmann 2021-05-28 22:52 ` Paul Moore 2021-05-28 22:52 ` Paul Moore 2021-05-29 18:48 ` Paul Moore 2021-05-29 18:48 ` Paul Moore 2021-05-31 8:24 ` Daniel Borkmann 2021-05-31 8:24 ` Daniel Borkmann 2021-06-01 20:47 ` Paul Moore 2021-06-01 20:47 ` Paul Moore 2021-06-02 12:40 ` Daniel Borkmann 2021-06-02 12:40 ` Daniel Borkmann 2021-06-02 15:13 ` Paul Moore 2021-06-02 15:13 ` Paul Moore 2021-06-03 18:52 ` Daniel Borkmann 2021-06-03 18:52 ` Daniel Borkmann 2021-06-04 4:50 ` Paul Moore 2021-06-04 4:50 ` Paul Moore 2021-06-04 18:02 ` Daniel Borkmann 2021-06-04 18:02 ` Daniel Borkmann 2021-06-04 23:34 ` Paul Moore 2021-06-04 23:34 ` Paul Moore 2021-06-05 0:08 ` Alexei Starovoitov 2021-06-05 0:08 ` Alexei Starovoitov 2021-06-05 18:10 ` Casey Schaufler 2021-06-05 18:10 ` Casey Schaufler 2021-06-05 18:17 ` Linus Torvalds 2021-06-05 18:17 ` Linus Torvalds 2021-06-06 2:11 ` Paul Moore 2021-06-06 2:11 ` Paul Moore 2021-06-06 1:30 ` Paul Moore 2021-06-06 1:30 ` Paul Moore 2021-06-02 13:39 ` Ondrej Mosnacek 2021-06-02 13:39 ` Ondrej Mosnacek 2021-06-03 17:46 ` Paul Moore 2021-06-03 17:46 ` Paul Moore 2021-06-08 11:01 ` Ondrej Mosnacek 2021-06-08 11:01 ` Ondrej Mosnacek 2021-06-09 2:40 ` Paul Moore 2021-06-09 2:40 ` Paul Moore 2021-05-28 13:58 ` Steven Rostedt 2021-05-28 13:58 ` Steven Rostedt
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