linux-kernel - Re: [PATCH 1/1] security: Propagate universal pointer data in bpf hooks

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CAPhsuW5Xzv7hsuG9RzO+KdxMXO3JCpC6UOTFDZiYGf_Vnfpo5g@mail.gmail.com>
Date: Wed, 26 Feb 2025 14:02:12 -0800
From: Song Liu <song@...nel.org>
To: Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc: Blaise Boscaccy <bboscaccy@...ux.microsoft.com>, Paul Moore <paul@...l-moore.com>, 
	James Morris <jmorris@...ei.org>, "Serge E. Hallyn" <serge@...lyn.com>, 
	Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, 
	John Fastabend <john.fastabend@...il.com>, Andrii Nakryiko <andrii@...nel.org>, 
	Martin KaFai Lau <martin.lau@...ux.dev>, Eduard Zingerman <eddyz87@...il.com>, 
	Yonghong Song <yonghong.song@...ux.dev>, KP Singh <kpsingh@...nel.org>, 
	Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>, 
	Stephen Smalley <stephen.smalley.work@...il.com>, Ondrej Mosnacek <omosnace@...hat.com>, 
	LSM List <linux-security-module@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>, 
	bpf <bpf@...r.kernel.org>, selinux@...r.kernel.org
Subject: Re: [PATCH 1/1] security: Propagate universal pointer data in bpf hooks

On Wed, Feb 26, 2025 at 8:00 AM Alexei Starovoitov
<alexei.starovoitov@...il.com> wrote:
>
> On Tue, Feb 25, 2025 at 11:06 PM Song Liu <song@...nel.org> wrote:
> >
> > On Tue, Feb 25, 2025 at 4:31 PM Blaise Boscaccy
> > <bboscaccy@...ux.microsoft.com> wrote:
> > >
> > > Certain bpf syscall subcommands are available for usage from both
> > > userspace and the kernel. LSM modules or eBPF gatekeeper programs may
> > > need to take a different course of action depending on whether or not
> > > a BPF syscall originated from the kernel or userspace.
> > >
> > > Additionally, some of the bpf_attr struct fields contain pointers to
> > > arbitrary memory. Currently the functionality to determine whether or
> > > not a pointer refers to kernel memory or userspace memory is exposed
> > > to the bpf verifier, but that information is missing from various LSM
> > > hooks.
> > >
> > > Here we augment the LSM hooks to provide this data, by simply passing
> > > the corresponding universal pointer in any hook that contains already
> > > contains a bpf_attr struct that corresponds to a subcommand that may
> > > be called from the kernel.
> >
> > I think this information is useful for LSM hooks.
> >
> > Question: Do we need a full bpfptr_t for these hooks, or just a boolean
> > "is_kernel or not"?
>
> +1
> Just passing the bool should do.
> Passing uattr is a footgun. Last thing we need is to open up TOCTOU concerns.

Shall we also replace uattr with bool is_kernel in verifier.c? It appears to be
a good cleanup.

Thanks,
Song