From: KP Singh <kpsingh@chromium.org>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: KP Singh <kpsingh@chromium.org>,
linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
linux-security-module@vger.kernel.org,
Daniel Borkmann <daniel@iogearbox.net>,
James Morris <jmorris@namei.org>,
Kees Cook <keescook@chromium.org>, Jann Horn <jannh@google.com>,
"David S. Miller" <davem@davemloft.net>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH bpf-next v4 3/8] bpf: lsm: provide attachment points for BPF LSM programs
Date: Fri, 21 Feb 2020 12:47:10 +0100 [thread overview]
Message-ID: <20200221114710.GB56944@google.com> (raw)
In-Reply-To: <20200221022537.wbmhdfkdbfvw2pww@ast-mbp>
On 20-Feb 18:25, Alexei Starovoitov wrote:
> On Thu, Feb 20, 2020 at 06:52:45PM +0100, KP Singh wrote:
> > From: KP Singh <kpsingh@google.com>
> >
> > The BPF LSM programs are implemented as fexit trampolines to avoid the
> > overhead of retpolines. These programs cannot be attached to security_*
> > wrappers as there are quite a few security_* functions that do more than
> > just calling the LSM callbacks.
> >
> > This was discussed on the lists in:
> >
> > https://lore.kernel.org/bpf/20200123152440.28956-1-kpsingh@chromium.org/T/#m068becce588a0cdf01913f368a97aea4c62d8266
> >
> > Adding a NOP callback after all the static LSM callbacks are called has
> > the following benefits:
> >
> > - The BPF programs run at the right stage of the security_* wrappers.
> > - They run after all the static LSM hooks allowed the operation,
> > therefore cannot allow an action that was already denied.
> >
> > There are some hooks which do not call call_int_hooks or
> > call_void_hooks. It's not possible to call the bpf_lsm_* functions
> > without checking if there is BPF LSM program attached to these hooks.
> > This is added further in a subsequent patch. For now, these hooks are
> > marked as NO_BPF (i.e. attachment of BPF programs is not possible).
>
> the commit log doesn't match the code.
Fixed. Thanks!
>
> > +
> > +/* For every LSM hook that allows attachment of BPF programs, declare a NOP
> > + * function where a BPF program can be attached as an fexit trampoline.
> > + */
> > +#define LSM_HOOK(RET, NAME, ...) LSM_HOOK_##RET(NAME, __VA_ARGS__)
> > +#define LSM_HOOK_int(NAME, ...) noinline int bpf_lsm_##NAME(__VA_ARGS__) \
>
> Did you check generated asm?
> I think I saw cases when gcc ignored 'noinline' when function is defined in the
> same file and still performed inlining while keeping the function body.
> To be safe I think __weak is necessary. That will guarantee noinline.
Sure, will change it to __weak.
>
> And please reduce your cc next time. It's way too long.
Will do.
- KP
next prev parent reply other threads:[~2020-02-21 11:47 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-20 17:52 [PATCH bpf-next v4 0/8] MAC and Audit policy using eBPF (KRSI) KP Singh
2020-02-20 17:52 ` [PATCH bpf-next v4 1/8] bpf: Introduce BPF_PROG_TYPE_LSM KP Singh
2020-02-20 17:52 ` [PATCH bpf-next v4 2/8] security: Refactor declaration of LSM hooks KP Singh
2020-02-20 17:52 ` [PATCH bpf-next v4 3/8] bpf: lsm: provide attachment points for BPF LSM programs KP Singh
2020-02-21 2:25 ` Alexei Starovoitov
2020-02-21 11:47 ` KP Singh [this message]
[not found] ` <0ef26943-9619-3736-4452-fec536a8d169@schaufler-ca.com>
2020-02-21 11:44 ` KP Singh
2020-02-21 18:23 ` Casey Schaufler
[not found] ` <202002211946.A23A987@keescook>
2020-02-23 22:08 ` Alexei Starovoitov
2020-02-24 16:32 ` Casey Schaufler
2020-02-24 17:13 ` KP Singh
2020-02-24 18:45 ` Casey Schaufler
2020-02-24 21:41 ` Kees Cook
2020-02-24 22:29 ` Casey Schaufler
2020-02-25 5:41 ` Alexei Starovoitov
2020-02-25 15:31 ` Kees Cook
2020-02-25 19:31 ` KP Singh
2020-02-26 0:30 ` Casey Schaufler
2020-02-26 5:15 ` KP Singh
2020-02-26 15:35 ` Casey Schaufler
2020-02-25 19:29 ` KP Singh
2020-02-20 17:52 ` [PATCH bpf-next v4 4/8] bpf: lsm: Add support for enabling/disabling BPF hooks KP Singh
2020-02-21 18:57 ` Casey Schaufler
2020-02-21 19:11 ` James Morris
2020-02-22 4:26 ` Kees Cook
2020-02-20 17:52 ` [PATCH bpf-next v4 5/8] bpf: lsm: Implement attach, detach and execution KP Singh
2020-02-21 2:17 ` Alexei Starovoitov
2020-02-21 12:02 ` KP Singh
2020-02-20 17:52 ` [PATCH bpf-next v4 6/8] tools/libbpf: Add support for BPF_PROG_TYPE_LSM KP Singh
2020-02-25 6:45 ` Andrii Nakryiko
2020-02-20 17:52 ` [PATCH bpf-next v4 7/8] bpf: lsm: Add selftests " KP Singh
2020-02-20 17:52 ` [PATCH bpf-next v4 8/8] bpf: lsm: Add Documentation KP Singh
2020-02-21 19:19 ` [PATCH bpf-next v4 0/8] MAC and Audit policy using eBPF (KRSI) Casey Schaufler
2020-02-21 19:41 ` KP Singh
2020-02-21 22:31 ` Casey Schaufler
2020-02-21 23:09 ` KP Singh
2020-02-21 23:49 ` Casey Schaufler
2020-02-22 0:22 ` Kees Cook
2020-02-22 1:04 ` Casey Schaufler
2020-02-22 3:36 ` Kees Cook
2020-02-27 18:40 ` Dr. Greg
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