From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: KP Singh <kpsingh@chromium.org>
Cc: Kees Cook <keescook@chromium.org>,
open list <linux-kernel@vger.kernel.org>,
bpf <bpf@vger.kernel.org>,
linux-security-module@vger.kernel.org,
Brendan Jackman <jackmanb@google.com>,
Florent Revest <revest@google.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
James Morris <jmorris@namei.org>, Paul Turner <pjt@google.com>,
Jann Horn <jannh@google.com>,
Florent Revest <revest@chromium.org>,
Brendan Jackman <jackmanb@chromium.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH bpf-next v5 5/7] bpf: lsm: Initialize the BPF LSM hooks
Date: Mon, 23 Mar 2020 13:21:02 -0700 [thread overview]
Message-ID: <CAEf4BzZTsssnKgRFEzZBOnBMjCxk2wzkq7j_bOHmPpt5RmhqKA@mail.gmail.com> (raw)
In-Reply-To: <20200323194759.GB18787@chromium.org>
On Mon, Mar 23, 2020 at 12:48 PM KP Singh <kpsingh@chromium.org> wrote:
>
> On 23-Mär 12:44, Kees Cook wrote:
> > On Mon, Mar 23, 2020 at 05:44:13PM +0100, KP Singh wrote:
> > > From: KP Singh <kpsingh@google.com>
> > >
> > > The bpf_lsm_ nops are initialized into the LSM framework like any other
> > > LSM. Some LSM hooks do not have 0 as their default return value. The
> > > __weak symbol for these hooks is overridden by a corresponding
> > > definition in security/bpf/hooks.c
> > >
> > > The LSM can be enabled / disabled with CONFIG_LSM.
> > >
> > > Signed-off-by: KP Singh <kpsingh@google.com>
> >
> > Nice! This is super clean on the LSM side of things. :)
> >
> > One note below...
> >
> > > Reviewed-by: Brendan Jackman <jackmanb@google.com>
>
> [...]
>
> > > +
> > > +/*
> > > + * Copyright (C) 2020 Google LLC.
> > > + */
> > > +#include <linux/lsm_hooks.h>
> > > +#include <linux/bpf_lsm.h>
> > > +
> > > +/* Some LSM hooks do not have 0 as their default return values. Override the
> > > + * __weak definitons generated by default for these hooks
> >
> > If you wanted to avoid this, couldn't you make the default return value
> > part of lsm_hooks.h?
> >
> > e.g.:
> >
> > LSM_HOOK(int, -EOPNOTSUPP, inode_getsecurity, struct inode *inode,
> > const char *name, void **buffer, bool alloc)
> >
> > ...
> >
> > #define LSM_HOOK(RET, DEFAULT, NAME, ...) \
> > LSM_HOOK_##RET(NAME, DEFAULT, __VA_ARGS__)
> > ...
> > #define LSM_HOOK_int(NAME, DEFAULT, ...) \
> > noinline int bpf_lsm_##NAME(__VA_ARGS__) \
> > { \
> > return (DEFAULT); \
> > }
> >
> > Then all the __weak stuff is gone, and the following 4 functions don't
> > need to be written out, and the information is available to the macros
> > if anyone else might ever want it.
>
> Thanks, I like it!
>
> If no-one objects, I will update it in the next revision.
>
I was about to propose the same, explicit default value seems like a
much cleaner and more straightforward way to do this.
> - KP
>
> >
> > -Kees
> >
> > > + */
> > > +noinline int bpf_lsm_inode_getsecurity(struct inode *inode, const char *name,
> > > + void **buffer, bool alloc)
> > > +};
>
> [...]
>
> > > --
> > > 2.20.1
> > >
> >
> > --
> > Kees Cook
next prev parent reply other threads:[~2020-03-23 20:21 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-23 16:44 [PATCH bpf-next v5 0/8] MAC and Audit policy using eBPF (KRSI) KP Singh
2020-03-23 16:44 ` [PATCH bpf-next v5 1/7] bpf: Introduce BPF_PROG_TYPE_LSM KP Singh
2020-03-23 19:02 ` Yonghong Song
2020-03-23 16:44 ` [PATCH bpf-next v5 2/7] security: Refactor declaration of LSM hooks KP Singh
2020-03-23 19:33 ` Kees Cook
2020-03-23 19:56 ` Andrii Nakryiko
2020-03-24 16:06 ` KP Singh
2020-03-23 16:44 ` [PATCH bpf-next v5 3/7] bpf: lsm: provide attachment points for BPF LSM programs KP Singh
2020-03-23 19:04 ` Yonghong Song
2020-03-23 19:33 ` Kees Cook
2020-03-23 19:59 ` Andrii Nakryiko
2020-03-24 10:39 ` KP Singh
2020-03-24 16:12 ` KP Singh
2020-03-24 21:26 ` Andrii Nakryiko
2020-03-24 22:39 ` KP Singh
2020-03-23 16:44 ` [PATCH bpf-next v5 4/7] bpf: lsm: Implement attach, detach and execution KP Singh
2020-03-23 19:16 ` Yonghong Song
2020-03-23 19:44 ` KP Singh
2020-03-23 20:18 ` Andrii Nakryiko
2020-03-24 19:00 ` KP Singh
2020-03-24 14:35 ` Stephen Smalley
2020-03-24 14:50 ` KP Singh
2020-03-24 14:58 ` Stephen Smalley
2020-03-24 16:25 ` Casey Schaufler
2020-03-24 17:49 ` Stephen Smalley
2020-03-24 18:01 ` Kees Cook
2020-03-24 18:06 ` KP Singh
2020-03-24 18:21 ` Stephen Smalley
2020-03-24 18:27 ` KP Singh
2020-03-24 18:31 ` KP Singh
2020-03-24 18:34 ` Kees Cook
2020-03-24 18:33 ` Kees Cook
2020-03-23 16:44 ` [PATCH bpf-next v5 5/7] bpf: lsm: Initialize the BPF LSM hooks KP Singh
2020-03-23 19:44 ` Kees Cook
2020-03-23 19:47 ` KP Singh
2020-03-23 20:21 ` Andrii Nakryiko [this message]
2020-03-23 20:47 ` Casey Schaufler
2020-03-23 21:44 ` Kees Cook
2020-03-23 21:58 ` Casey Schaufler
2020-03-23 22:12 ` Kees Cook
2020-03-23 23:39 ` Casey Schaufler
2020-03-24 1:53 ` KP Singh
2020-03-25 14:35 ` KP Singh
2020-03-24 1:13 ` Casey Schaufler
2020-03-24 1:52 ` KP Singh
2020-03-24 14:37 ` Stephen Smalley
2020-03-24 14:42 ` KP Singh
2020-03-24 14:51 ` Stephen Smalley
2020-03-24 14:51 ` KP Singh
2020-03-24 17:57 ` Kees Cook
2020-03-23 16:44 ` [PATCH bpf-next v5 6/7] tools/libbpf: Add support for BPF_PROG_TYPE_LSM KP Singh
2020-03-23 19:21 ` Yonghong Song
2020-03-23 20:25 ` Andrii Nakryiko
2020-03-24 1:57 ` KP Singh
2020-03-23 16:44 ` [PATCH bpf-next v5 7/7] bpf: lsm: Add selftests " KP Singh
2020-03-23 20:04 ` Yonghong Song
2020-03-24 20:04 ` KP Singh
2020-03-24 23:54 ` Andrii Nakryiko
2020-03-25 0:36 ` KP Singh
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