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From: Kees Cook <keescook@chromium.org>
To: KP Singh <kpsingh@chromium.org>
Cc: linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	James Morris <jmorris@namei.org>,
	Thomas Garnier <thgarnie@chromium.org>,
	Michael Halcrow <mhalcrow@google.com>,
	Paul Turner <pjt@google.com>,
	Brendan Gregg <brendan.d.gregg@gmail.com>,
	Jann Horn <jannh@google.com>, Matthew Garrett <mjg59@google.com>,
	Christian Brauner <christian@brauner.io>,
	Florent Revest <revest@chromium.org>,
	Brendan Jackman <jackmanb@chromium.org>,
	Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
	Yonghong Song <yhs@fb.com>, "Serge E. Hallyn" <serge@hallyn.com>,
	"David S. Miller" <davem@davemloft.net>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Nicolas Ferre <nicolas.ferre@microchip.com>,
	Stanislav Fomichev <sdf@google.com>,
	Quentin Monnet <quentin.monnet@netronome.com>,
	Andrey Ignatov <rdna@fb.com>, Joe Stringer <joe@wand.net.nz>
Subject: Re: [PATCH bpf-next v4 4/8] bpf: lsm: Add support for enabling/disabling BPF hooks
Date: Fri, 21 Feb 2020 20:26:04 -0800	[thread overview]
Message-ID: <202002212023.1712A8AB@keescook> (raw)
In-Reply-To: <20200220175250.10795-5-kpsingh@chromium.org>

On Thu, Feb 20, 2020 at 06:52:46PM +0100, KP Singh wrote:
> index aa111392a700..569cc07d5e34 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -804,6 +804,13 @@ int security_vm_enough_memory_mm(struct mm_struct *mm, long pages)
>  			break;
>  		}
>  	}
> +#ifdef CONFIG_BPF_LSM
> +	if (HAS_BPF_LSM_PROG(vm_enough_memory)) {
> +		rc = bpf_lsm_vm_enough_memory(mm, pages);
> +		if (rc <= 0)
> +			cap_sys_admin = 0;
> +	}
> +#endif

This pattern of using #ifdef in code is not considered best practice.
Using in-code IS_ENABLED(CONFIG_BPF_LSM) is preferred. But since this
pattern always uses HAS_BPF_LSM_PROG(), you could fold the
IS_ENABLED() into the definition of HAS_BPF_LSM_PROG itself -- or more
likely, have the macro defined as:

#ifdef CONFIG_BPF_LSM
# define HAS_BPF_LSM_PROG(x)    ....existing implementation....
#else
# define HAS_BPF_LSM_PROG(x)	false
#endif

Then none of these ifdefs are needed.

-- 
Kees Cook

  parent reply	other threads:[~2020-02-22  4:26 UTC|newest]

Thread overview: 45+ 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
2020-02-20 23:49   ` Casey Schaufler
2020-02-21 11:44     ` KP Singh
2020-02-21 18:23       ` Casey Schaufler
2020-02-22  4:22     ` Kees Cook
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
2020-02-24 16:09       ` Casey Schaufler
2020-02-24 17:23       ` KP Singh
2020-02-21  2:25   ` Alexei Starovoitov
2020-02-21 11:47     ` 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 [this message]
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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