linux-kernel - Re: [PATCH bpf-next v7 4/8] bpf: lsm: Implement attach, detach and execution

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Message-ID: <20200326193921.GA15273@chromium.org>
Date:   Thu, 26 Mar 2020 20:39:21 +0100
From:   KP Singh <kpsingh@...omium.org>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc:     open list <linux-kernel@...r.kernel.org>,
        bpf <bpf@...r.kernel.org>, linux-security-module@...r.kernel.org,
        Brendan Jackman <jackmanb@...gle.com>,
        Florent Revest <revest@...gle.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        James Morris <jmorris@...ei.org>,
        Kees Cook <keescook@...omium.org>,
        Paul Turner <pjt@...gle.com>, Jann Horn <jannh@...gle.com>,
        Florent Revest <revest@...omium.org>,
        Brendan Jackman <jackmanb@...omium.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH bpf-next v7 4/8] bpf: lsm: Implement attach, detach and
 execution

On 26-Mär 12:12, Andrii Nakryiko wrote:
> On Thu, Mar 26, 2020 at 7:29 AM KP Singh <kpsingh@...omium.org> wrote:
> >
> > From: KP Singh <kpsingh@...gle.com>
> >
> > JITed BPF programs are dynamically attached to the LSM hooks
> > using BPF trampolines. The trampoline prologue generates code to handle
> > conversion of the signature of the hook to the appropriate BPF context.
> >
> > The allocated trampoline programs are attached to the nop functions
> > initialized as LSM hooks.
> >
> > BPF_PROG_TYPE_LSM programs must have a GPL compatible license and
> > and need CAP_SYS_ADMIN (required for loading eBPF programs).
> >
> > Upon attachment:
> >
> > * A BPF fexit trampoline is used for LSM hooks with a void return type.
> > * A BPF fmod_ret trampoline is used for LSM hooks which return an
> >   int. The attached programs can override the return value of the
> >   bpf LSM hook to indicate a MAC Policy decision.
> >
> > Signed-off-by: KP Singh <kpsingh@...gle.com>
> > Reviewed-by: Brendan Jackman <jackmanb@...gle.com>
> > Reviewed-by: Florent Revest <revest@...gle.com>
> > ---
> 
> Acked-by: Andrii Nakryiko <andriin@...com>
> 
> 
> >  include/linux/bpf_lsm.h | 11 ++++++++
> >  kernel/bpf/bpf_lsm.c    | 28 ++++++++++++++++++++
> >  kernel/bpf/btf.c        |  9 ++++++-
> >  kernel/bpf/syscall.c    | 57 ++++++++++++++++++++++++++++-------------
> >  kernel/bpf/trampoline.c | 17 +++++++++---
> >  kernel/bpf/verifier.c   | 19 +++++++++++---
> >  6 files changed, 114 insertions(+), 27 deletions(-)
> >
> 
> [...]
> 
> > @@ -2479,6 +2496,10 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr)
> >                 }
> >                 buf[sizeof(buf) - 1] = 0;
> >                 tp_name = buf;
> > +               break;
> > +       default:
> > +                       err = -EINVAL;
> > +                       goto out_put_prog;
> >         }
> 
> is indentation off here or it's my email client?

You're mail client is fine :) It's me.

- KP

> 
> [...]