From: Jiri Olsa <olsajiri@gmail.com>
To: KP Singh <kpsingh@kernel.org>
Cc: Jiri Olsa <olsajiri@gmail.com>,
linux-security-module@vger.kernel.org, bpf@vger.kernel.org,
paul@paul-moore.com, keescook@chromium.org,
casey@schaufler-ca.com, song@kernel.org, daniel@iogearbox.net,
ast@kernel.org, renauld@google.com
Subject: Re: [PATCH v5 4/5] bpf: Only enable BPF LSM hooks when an LSM program is attached
Date: Fri, 6 Oct 2023 11:05:19 +0200 [thread overview]
Message-ID: <ZR/Nz+aPH4sIQMwT@krava> (raw)
In-Reply-To: <ZR+2+gQ3B3tgFI/8@krava>
On Fri, Oct 06, 2023 at 09:27:57AM +0200, Jiri Olsa wrote:
SNIP
> > static int __bpf_trampoline_link_prog(struct bpf_tramp_link *link,
> > struct bpf_trampoline *tr)
> > {
> > enum bpf_tramp_prog_type kind;
> > struct bpf_tramp_link *link_exiting;
> > - int err = 0, num_lsm_progs = 0;
> > + int err = 0;
> > int cnt = 0, i;
> >
> > kind = bpf_attach_type_to_tramp(link->link.prog);
> > @@ -547,15 +566,14 @@ static int __bpf_trampoline_link_prog(struct
> > bpf_tramp_link *link, struct bpf_tr
> > /* prog already linked */
> > return -EBUSY;
> >
> > - if (link_exiting->link.prog->type == BPF_PROG_TYPE_LSM)
> > - num_lsm_progs++;
> > }
> >
> > - if (!num_lsm_progs && link->link.prog->type == BPF_PROG_TYPE_LSM)
> > - bpf_lsm_toggle_hook(tr->func.addr, true);
> > -
> > hlist_add_head(&link->tramp_hlist, &tr->progs_hlist[kind]);
> > tr->progs_cnt[kind]++;
> > +
> > + if (link->link.prog->type == BPF_PROG_TYPE_LSM)
> > + bpf_trampoline_toggle_lsm(tr, kind);
>
> how about keeping BPF_PROG_TYPE_LSM progs type count of attached programs
> in bpf_trampoline and toggle lsm on first coming in and last going out?
hm we actually allow other tracing program types to attach to bpf_lsm_*
functions, so I wonder we should toggle the lsm hook for each program
type (for bpf_lsm_* trampolines) because they'd expect the hook is called
but I'm not sure it's a valid use case to have like normal fentry program
attached to bpf_lsm_XXX function
jirka
>
> also the trampoline attach is actually made in bpf_trampoline_update,
> so I wonder it'd make more sense to put it in there, but it's already
> complicated, so it actually might be easier in here
>
> jirka
>
> > +
> > err = bpf_trampoline_update(tr, true /* lock_direct_mutex */);
> > if (err) {
> > hlist_del_init(&link->tramp_hlist);
> > @@ -578,7 +596,6 @@ static int __bpf_trampoline_unlink_prog(struct
> > bpf_tramp_link *link, struct bpf_
> > {
> > struct bpf_tramp_link *link_exiting;
> > enum bpf_tramp_prog_type kind;
> > - bool lsm_link_found = false;
> > int err, num_lsm_progs = 0;
> >
> > kind = bpf_attach_type_to_tramp(link->link.prog);
> > @@ -595,18 +612,14 @@ static int __bpf_trampoline_unlink_prog(struct
> > bpf_tramp_link *link, struct bpf_
> > tramp_hlist) {
> > if (link_exiting->link.prog->type == BPF_PROG_TYPE_LSM)
> > num_lsm_progs++;
> > -
> > - if (link_exiting->link.prog == link->link.prog)
> > - lsm_link_found = true;
> > }
> > }
> >
> > hlist_del_init(&link->tramp_hlist);
> > tr->progs_cnt[kind]--;
> >
> > - if (lsm_link_found && num_lsm_progs == 1)
> > - bpf_lsm_toggle_hook(tr->func.addr, false);
> > -
> > + if (link->link.prog->type == BPF_PROG_TYPE_LSM)
> > + bpf_trampoline_toggle_lsm(tr, kind);
> > return bpf_trampoline_update(tr, true /* lock_direct_mutex */);
> > }
> >
> >
> > - KP
next prev parent reply other threads:[~2023-10-06 9:05 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-28 20:24 [PATCH v5 0/5] Reduce overhead of LSMs with static calls KP Singh
2023-09-28 20:24 ` [PATCH v5 1/5] kernel: Add helper macros for loop unrolling KP Singh
2023-09-28 20:24 ` [PATCH v5 2/5] security: Count the LSMs enabled at compile time KP Singh
2023-09-29 0:37 ` Kees Cook
2023-09-28 20:24 ` [PATCH v5 3/5] security: Replace indirect LSM hook calls with static calls KP Singh
2023-09-30 16:13 ` kernel test robot
2023-09-30 20:40 ` Kees Cook
2023-10-04 0:09 ` KP Singh
2023-09-28 20:24 ` [PATCH v5 4/5] bpf: Only enable BPF LSM hooks when an LSM program is attached KP Singh
2023-10-05 8:09 ` Jiri Olsa
2023-10-05 13:26 ` KP Singh
2023-10-05 13:27 ` KP Singh
2023-10-05 13:52 ` Jiri Olsa
2023-10-05 16:07 ` KP Singh
2023-10-06 7:27 ` Jiri Olsa
2023-10-06 9:05 ` Jiri Olsa [this message]
2023-10-06 10:57 ` KP Singh
2023-10-06 18:32 ` KP Singh
2023-09-28 20:24 ` [PATCH v5 5/5] security: Add CONFIG_SECURITY_HOOK_LIKELY KP Singh
2023-09-29 0:38 ` Kees Cook
2023-09-29 0:41 ` [PATCH v5 0/5] Reduce overhead of LSMs with static calls Kees Cook
2023-10-02 11:06 ` Paolo Abeni
2023-10-02 11:09 ` KP Singh
2023-10-02 13:27 ` Paolo Abeni
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