From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexei Starovoitov Subject: Re: [RFC v3 14/22] bpf/cgroup: Make cgroup_bpf_update() return an error code Date: Wed, 14 Sep 2016 14:16:10 -0700 Message-ID: <20160914211608.GB57174@ast-mbp.thefacebook.com> References: <20160914072415.26021-1-mic@digikod.net> <20160914072415.26021-15-mic@digikod.net> Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to :user-agent; bh=BmU0Yqhg5VonzkgwA5yWgade440AA8JDJ/YxLQ6EwLs=; b=c8MVcKzJzcT37ccQjMeBinxYkK5OH8yjtQfd5KPGOcI3j9ag1ik3vXklbYwOaIctp9 v8rjNPU+mqb7jcPNmvTIAFnt678n+r/aN9Lv3tvotB6uNzzWQUKlBzCxa80rqKFxl+Tq KKhwyBzmjsCxHM3OzMiZ34OsK9RrTQd07iH05vZpc2iM1+RxIOQjpIVjn/JereGjkxtt gtPFKkhHa0YkOgd1+58yp6pbB5Vrn2qCF3v6mtRgEJhl6DAZvOWA6rKxRicLo7FsxYMW yGACPQz8l3bPUUcFfDGaoiWuN2wjGQVZ6J1mLGYiw419mJPp5kElqB5nu0DVzPcfeGux 6AeQ== Content-Disposition: inline In-Reply-To: <20160914072415.26021-15-mic@digikod.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="iso-8859-1" To: =?iso-8859-1?Q?Micka=EBl_Sala=FCn?= Cc: linux-kernel@vger.kernel.org, Alexei Starovoitov , Andy Lutomirski , Arnd Bergmann , Casey Schaufler , Daniel Borkmann , Daniel Mack , David Drysdale , "David S . Miller" , Elena Reshetova , "Eric W . Biederman" , James Morris , Kees Cook , Paul Moore , Sargun Dhillon , "Serge E . Hallyn" , Tejun Heo , Will Drewry , kernel-hardening@lists.openwall.com, linux-api@vger.kernel.org, linux-security-module@vger.kern On Wed, Sep 14, 2016 at 09:24:07AM +0200, Micka=EBl Sala=FCn wrote: > This will be useful to support Landlock for the next commits. >=20 > Signed-off-by: Micka=EBl Sala=FCn > Cc: Alexei Starovoitov > Cc: Daniel Borkmann > Cc: Daniel Mack > Cc: David S. Miller > Cc: Tejun Heo I think this is good to do regardless. Sooner or later cgroup_bpf_update will start rejecting the prog attach. Like we discussed to have a flag that would dissallow processeses lower in the cgroup hierarchy to install their own bpf programs. It will be minimal change to bpf_prog_attach() error handling, but will greatly help Mickael to build stuff on top. DanielM can you refactor your patch to do that from the start ? Thanks! > --- > include/linux/bpf-cgroup.h | 4 ++-- > kernel/bpf/cgroup.c | 3 ++- > kernel/bpf/syscall.c | 10 ++++++---- > kernel/cgroup.c | 6 ++++-- > 4 files changed, 14 insertions(+), 9 deletions(-) >=20 > diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h > index 2234042d7f61..6cca7924ee17 100644 > --- a/include/linux/bpf-cgroup.h > +++ b/include/linux/bpf-cgroup.h > @@ -31,13 +31,13 @@ struct cgroup_bpf { > void cgroup_bpf_put(struct cgroup *cgrp); > void cgroup_bpf_inherit(struct cgroup *cgrp, struct cgroup *parent); > =20 > -void __cgroup_bpf_update(struct cgroup *cgrp, > +int __cgroup_bpf_update(struct cgroup *cgrp, > struct cgroup *parent, > struct bpf_prog *prog, > enum bpf_attach_type type); > =20 > /* Wrapper for __cgroup_bpf_update() protected by cgroup_mutex */ > -void cgroup_bpf_update(struct cgroup *cgrp, > +int cgroup_bpf_update(struct cgroup *cgrp, > struct bpf_prog *prog, > enum bpf_attach_type type); > =20 > diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c > index 782878ec4f2d..7b75fa692617 100644 > --- a/kernel/bpf/cgroup.c > +++ b/kernel/bpf/cgroup.c > @@ -83,7 +83,7 @@ void cgroup_bpf_inherit(struct cgroup *cgrp, struct cgr= oup *parent) > * > * Must be called with cgroup_mutex held. > */ > -void __cgroup_bpf_update(struct cgroup *cgrp, > +int __cgroup_bpf_update(struct cgroup *cgrp, > struct cgroup *parent, > struct bpf_prog *prog, > enum bpf_attach_type type) > @@ -117,6 +117,7 @@ void __cgroup_bpf_update(struct cgroup *cgrp, > bpf_prog_put(old_pinned.prog); > static_branch_dec(&cgroup_bpf_enabled_key); > } > + return 0; > } > =20 > /** > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > index 45a91d511119..c978f2d9a1b3 100644 > --- a/kernel/bpf/syscall.c > +++ b/kernel/bpf/syscall.c > @@ -831,6 +831,7 @@ static int bpf_prog_attach(const union bpf_attr *attr) > { > struct bpf_prog *prog; > struct cgroup *cgrp; > + int result; > =20 > if (!capable(CAP_NET_ADMIN)) > return -EPERM; > @@ -858,10 +859,10 @@ static int bpf_prog_attach(const union bpf_attr *at= tr) > return PTR_ERR(cgrp); > } > =20 > - cgroup_bpf_update(cgrp, prog, attr->attach_type); > + result =3D cgroup_bpf_update(cgrp, prog, attr->attach_type); > cgroup_put(cgrp); > =20 > - return 0; > + return result; > } > =20 > #define BPF_PROG_DETACH_LAST_FIELD attach_type > @@ -869,6 +870,7 @@ static int bpf_prog_attach(const union bpf_attr *attr) > static int bpf_prog_detach(const union bpf_attr *attr) > { > struct cgroup *cgrp; > + int result =3D 0; > =20 > if (!capable(CAP_NET_ADMIN)) > return -EPERM; > @@ -883,7 +885,7 @@ static int bpf_prog_detach(const union bpf_attr *attr) > if (IS_ERR(cgrp)) > return PTR_ERR(cgrp); > =20 > - cgroup_bpf_update(cgrp, NULL, attr->attach_type); > + result =3D cgroup_bpf_update(cgrp, NULL, attr->attach_type); > cgroup_put(cgrp); > break; > =20 > @@ -891,7 +893,7 @@ static int bpf_prog_detach(const union bpf_attr *attr) > return -EINVAL; > } > =20 > - return 0; > + return result; > } > #endif /* CONFIG_CGROUP_BPF */ > =20 > diff --git a/kernel/cgroup.c b/kernel/cgroup.c > index 87324ce481b1..48b650a640a9 100644 > --- a/kernel/cgroup.c > +++ b/kernel/cgroup.c > @@ -6450,15 +6450,17 @@ static __init int cgroup_namespaces_init(void) > subsys_initcall(cgroup_namespaces_init); > =20 > #ifdef CONFIG_CGROUP_BPF > -void cgroup_bpf_update(struct cgroup *cgrp, > +int cgroup_bpf_update(struct cgroup *cgrp, > struct bpf_prog *prog, > enum bpf_attach_type type) > { > struct cgroup *parent =3D cgroup_parent(cgrp); > + int result; > =20 > mutex_lock(&cgroup_mutex); > - __cgroup_bpf_update(cgrp, parent, prog, type); > + result =3D __cgroup_bpf_update(cgrp, parent, prog, type); > mutex_unlock(&cgroup_mutex); > + return result; > } > #endif /* CONFIG_CGROUP_BPF */ > =20 > --=20 > 2.9.3 >=20