Re: [PATCH v17 11/12] selftests/bpf: Add test for bpf_verify_pkcs7_signature() kfunc

From: KP Singh <kpsingh@kernel.org>
To: Roberto Sassu <roberto.sassu@huaweicloud.com>
Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
	martin.lau@linux.dev, song@kernel.org, yhs@fb.com,
	john.fastabend@gmail.com, sdf@google.com, haoluo@google.com,
	jolsa@kernel.org, mykolal@fb.com, dhowells@redhat.com,
	jarkko@kernel.org, rostedt@goodmis.org, mingo@redhat.com,
	paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com,
	shuah@kernel.org, bpf@vger.kernel.org, keyrings@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org,
	deso@posteo.net, memxor@gmail.com,
	Roberto Sassu <roberto.sassu@huawei.com>,
	Joanne Koong <joannelkoong@gmail.com>
Subject: Re: [PATCH v17 11/12] selftests/bpf: Add test for bpf_verify_pkcs7_signature() kfunc
Date: Thu, 15 Sep 2022 17:11:39 +0100	[thread overview]
Message-ID: <CACYkzJ7uraUdmGV9gMmTZs1OMb_3Q2DttoaxU-irmrXFudOweQ@mail.gmail.com> (raw)
In-Reply-To: <20220909120736.1027040-12-roberto.sassu@huaweicloud.com>

On Fri, Sep 9, 2022 at 1:10 PM Roberto Sassu
<roberto.sassu@huaweicloud.com> wrote:
>
> From: Roberto Sassu <roberto.sassu@huawei.com>
>

[...]

> +}
> diff --git a/tools/testing/selftests/bpf/progs/test_verify_pkcs7_sig.c b/tools/testing/selftests/bpf/progs/test_verify_pkcs7_sig.c
> new file mode 100644
> index 000000000000..4ceab545d99a
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_verify_pkcs7_sig.c
> @@ -0,0 +1,100 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +/*
> + * Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH
> + *
> + * Author: Roberto Sassu <roberto.sassu@huawei.com>
> + */
> +
> +#include "vmlinux.h"
> +#include <errno.h>
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +
> +#define MAX_DATA_SIZE (1024 * 1024)
> +#define MAX_SIG_SIZE 1024
> +
> +typedef __u8 u8;
> +typedef __u16 u16;
> +typedef __u32 u32;
> +typedef __u64 u64;

I think you can avoid this and just use u32 and u64 directly.

> +
> +struct bpf_dynptr {
> +       __u64 :64;
> +       __u64 :64;
> +} __attribute__((aligned(8)));
> +

I think you are doing this because including the uapi headers causes
type conflicts.
This does happen quite often. What do other folks think about doing
something like

#define DYNPTR(x) ((void *)x)

It seems like this will be an issue anytime we use the helpers with
vmlinux.h and users
will always have to define this type in their tests.

- KP

> +extern struct bpf_key *bpf_lookup_user_key(__u32 serial, __u64 flags) __ksym;
> +extern struct bpf_key *bpf_lookup_system_key(__u64 id) __ksym;
> +extern void bpf_key_put(struct bpf_key *key) __ksym;
> +extern int bpf_verify_pkcs7_signature(struct bpf_dynptr *data_ptr,
> +                                     struct bpf_dynptr *sig_ptr,
> +                                     struct bpf_key *trusted_keyring) __ksym;
> +
> +u32 monitored_pid;
> +u32 user_keyring_serial;
> +u64 system_keyring_id;
> +
> +struct data {
> +       u8 data[MAX_DATA_SIZE];
> +       u32 data_len;
> +       u8 sig[MAX_SIG_SIZE];
> +       u32 sig_len;
> +};
> +
> +struct {
> +       __uint(type, BPF_MAP_TYPE_ARRAY);
> +       __uint(max_entries, 1);
> +       __type(key, __u32);
> +       __type(value, struct data);
> +} data_input SEC(".maps");
> +
> +char _license[] SEC("license") = "GPL";
> +
> +SEC("lsm.s/bpf")
> +int BPF_PROG(bpf, int cmd, union bpf_attr *attr, unsigned int size)
> +{
> +       struct bpf_dynptr data_ptr, sig_ptr;
> +       struct data *data_val;
> +       struct bpf_key *trusted_keyring;
> +       u32 pid;
> +       u64 value;
> +       int ret, zero = 0;
> +
> +       pid = bpf_get_current_pid_tgid() >> 32;
> +       if (pid != monitored_pid)
> +               return 0;
> +
> +       data_val = bpf_map_lookup_elem(&data_input, &zero);
> +       if (!data_val)
> +               return 0;
> +
> +       bpf_probe_read(&value, sizeof(value), &attr->value);
> +
> +       bpf_copy_from_user(data_val, sizeof(struct data),
>

[...]

> --
> 2.25.1
>