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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: KP Singh <kpsingh@chromium.org>
Cc: 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 5/8] bpf: lsm: Implement attach, detach and execution
Date: Thu, 20 Feb 2020 18:17:57 -0800
Message-ID: <20200221021755.3z7ifyyeh6seo3zs@ast-mbp> (raw)
In-Reply-To: <20200220175250.10795-6-kpsingh@chromium.org>

On Thu, Feb 20, 2020 at 06:52:47PM +0100, KP Singh wrote:
> +
> +	/* This is the first program to be attached to the LSM hook, the hook
> +	 * needs to be enabled.
> +	 */
> +	if (prog->type == BPF_PROG_TYPE_LSM && tr->progs_cnt[kind] == 1)
> +		err = bpf_lsm_set_enabled(prog->aux->attach_func_name, true);
>  out:
>  	mutex_unlock(&tr->mutex);
>  	return err;
> @@ -336,7 +348,11 @@ int bpf_trampoline_unlink_prog(struct bpf_prog *prog)
>  	}
>  	hlist_del(&prog->aux->tramp_hlist);
>  	tr->progs_cnt[kind]--;
> -	err = bpf_trampoline_update(prog->aux->trampoline);
> +	err = bpf_trampoline_update(prog);
> +
> +	/* There are no more LSM programs, the hook should be disabled */
> +	if (prog->type == BPF_PROG_TYPE_LSM && tr->progs_cnt[kind] == 0)
> +		err = bpf_lsm_set_enabled(prog->aux->attach_func_name, false);

Overall looks good, but I don't think above logic works.
Consider lsm being attached, then fexit, then lsm detached, then fexit detached.
Both are kind==fexit and static_key stays enabled.

  reply index

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
     [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 [this message]
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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