From: KP Singh <kpsingh@chromium.org>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: KP Singh <kpsingh@chromium.org>,
open list <linux-kernel@vger.kernel.org>,
bpf <bpf@vger.kernel.org>,
Linux Security Module list
<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: Fri, 21 Feb 2020 13:02:40 +0100 [thread overview]
Message-ID: <CACYkzJ6E7FDE0xnnZPCmxgC+vEw1o4qcu9szV1DMeDeukbnFxQ@mail.gmail.com> (raw)
In-Reply-To: <20200221021755.3z7ifyyeh6seo3zs@ast-mbp>
On 20-Feb 18:17, Alexei Starovoitov wrote:
> 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.
You're right. I was weary of introducing a new kind (something like
BPF_TRAMP_LSM) since they are just fexit trampolines. For now, I
added nr_lsm_progs as a member in struct bpf_trampoline and refactored
the increment and decrement logic into inline helper functions e.g.
static inline void bpf_trampoline_dec_progs(struct bpf_prog *prog,
enum bpf_tramp_prog_type kind)
{
struct bpf_trampoline *tr = prog->aux->trampoline;
if (prog->type == BPF_PROG_TYPE_LSM)
tr->nr_lsm_progs--;
tr->progs_cnt[kind]--;
}
and doing the check as:
if (prog->type == BPF_PROG_TYPE_LSM && tr->nr_lsm_progs == 0)
err = bpf_lsm_set_enabled(prog->aux->attach_func_name, false);
This should work, If you're okay with it, I will update it in the next
revision of the patch-set.
- KP
next prev parent reply other threads:[~2020-02-21 12:02 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
[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 [this message]
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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