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Message-ID: <CAPhsuW5+2h9S_xnAY104frBpqhKYQk2wqc3Cp1fucNsHXwvVNQ@mail.gmail.com>
Date: Fri, 18 Mar 2022 13:51:10 -0700
From: Song Liu <song@...nel.org>
To: Benjamin Tissoires <benjamin.tissoires@...hat.com>
Cc: Greg KH <gregkh@...uxfoundation.org>,
Jiri Kosina <jikos@...nel.org>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>,
Martin KaFai Lau <kafai@...com>,
Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
John Fastabend <john.fastabend@...il.com>,
KP Singh <kpsingh@...nel.org>, Shuah Khan <shuah@...nel.org>,
Dave Marchevsky <davemarchevsky@...com>,
Joe Stringer <joe@...ium.io>, Jonathan Corbet <corbet@....net>,
Tero Kristo <tero.kristo@...ux.intel.com>,
open list <linux-kernel@...r.kernel.org>,
"open list:HID CORE LAYER" <linux-input@...r.kernel.org>,
Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
linux-kselftest@...r.kernel.org,
Linux Doc Mailing List <linux-doc@...r.kernel.org>
Subject: Re: [PATCH bpf-next v3 03/17] bpf/verifier: prevent non GPL programs
to be loaded against HID
On Fri, Mar 18, 2022 at 9:16 AM Benjamin Tissoires
<benjamin.tissoires@...hat.com> wrote:
>
> This is just to hammer the obvious because I suspect you can not already
> load a bpf HID program which is not GPL because all of the useful
> functions are GPL only.
>
> Anyway, this ensures that users are not tempted to bypass this requirement
> and will allow us to ship tested BPF programs in the kernel without having
> to aorry about the license.
>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>
Acked-by: Song Liu <songliubraving@...com>
>
> ---
>
> no changes in v3
>
> new in v2:
> - Note: I placed this statement in check_attach_btf_id() to be local to
> other similar checks (regarding LSM), however, I have no idea if this
> is the correct place. Please shout at me if it isn't.
> ---
> include/linux/bpf-hid.h | 8 ++++++++
> kernel/bpf/hid.c | 12 ++++++++++++
> kernel/bpf/verifier.c | 7 +++++++
> 3 files changed, 27 insertions(+)
>
> diff --git a/include/linux/bpf-hid.h b/include/linux/bpf-hid.h
> index 9c8dbd389995..7f596554fe8c 100644
> --- a/include/linux/bpf-hid.h
> +++ b/include/linux/bpf-hid.h
> @@ -2,6 +2,7 @@
> #ifndef _BPF_HID_H
> #define _BPF_HID_H
>
> +#include <linux/bpf_verifier.h>
> #include <linux/mutex.h>
> #include <uapi/linux/bpf.h>
> #include <uapi/linux/bpf_hid.h>
> @@ -69,6 +70,8 @@ int bpf_hid_prog_query(const union bpf_attr *attr,
> union bpf_attr __user *uattr);
> int bpf_hid_link_create(const union bpf_attr *attr,
> struct bpf_prog *prog);
> +int bpf_hid_verify_prog(struct bpf_verifier_log *vlog,
> + const struct bpf_prog *prog);
> #else
> static inline int bpf_hid_prog_query(const union bpf_attr *attr,
> union bpf_attr __user *uattr)
> @@ -81,6 +84,11 @@ static inline int bpf_hid_link_create(const union bpf_attr *attr,
> {
> return -EOPNOTSUPP;
> }
> +static inline int bpf_hid_verify_prog(struct bpf_verifier_log *vlog,
> + const struct bpf_prog *prog)
> +{
> + return -EOPNOTSUPP;
> +}
> #endif
>
> static inline bool bpf_hid_link_empty(struct bpf_hid *bpf,
> diff --git a/kernel/bpf/hid.c b/kernel/bpf/hid.c
> index c21dc05f6207..2dfeaaa8a83f 100644
> --- a/kernel/bpf/hid.c
> +++ b/kernel/bpf/hid.c
> @@ -34,6 +34,18 @@ void bpf_hid_set_hooks(struct bpf_hid_hooks *hooks)
> }
> EXPORT_SYMBOL_GPL(bpf_hid_set_hooks);
>
> +int bpf_hid_verify_prog(struct bpf_verifier_log *vlog,
> + const struct bpf_prog *prog)
> +{
> + if (!prog->gpl_compatible) {
> + bpf_log(vlog,
> + "HID programs must have a GPL compatible license\n");
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> BPF_CALL_3(bpf_hid_get_data, struct hid_bpf_ctx_kern*, ctx, u64, offset, u64, size)
> {
> if (!size)
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index cf92f9c01556..da06d633fb8d 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -21,6 +21,7 @@
> #include <linux/perf_event.h>
> #include <linux/ctype.h>
> #include <linux/error-injection.h>
> +#include <linux/bpf-hid.h>
> #include <linux/bpf_lsm.h>
> #include <linux/btf_ids.h>
>
> @@ -14272,6 +14273,12 @@ static int check_attach_btf_id(struct bpf_verifier_env *env)
> if (prog->type == BPF_PROG_TYPE_STRUCT_OPS)
> return check_struct_ops_btf_id(env);
>
> + if (prog->type == BPF_PROG_TYPE_HID) {
> + ret = bpf_hid_verify_prog(&env->log, prog);
> + if (ret < 0)
> + return ret;
> + }
> +
> if (prog->type != BPF_PROG_TYPE_TRACING &&
> prog->type != BPF_PROG_TYPE_LSM &&
> prog->type != BPF_PROG_TYPE_EXT)
> --
> 2.35.1
>
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