From: Song Liu <songliubraving@meta.com>
To: Eric Biggers <ebiggers@kernel.org>
Cc: Song Liu <song@kernel.org>, bpf <bpf@vger.kernel.org>,
"fsverity@lists.linux.dev" <fsverity@lists.linux.dev>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@kernel.org>,
Kernel Team <kernel-team@meta.com>,
"tytso@mit.edu" <tytso@mit.edu>,
"roberto.sassu@huaweicloud.com" <roberto.sassu@huaweicloud.com>
Subject: Re: [PATCH bpf-next 2/5] bpf, fsverity: Add kfunc bpf_get_fsverity_digest
Date: Tue, 17 Oct 2023 14:16:18 +0000 [thread overview]
Message-ID: <338D3CA0-2AAA-4F61-A336-3739DE8EE2DB@fb.com> (raw)
In-Reply-To: <20231017054637.GH1907@sol.localdomain>
> On Oct 16, 2023, at 10:46 PM, Eric Biggers <ebiggers@kernel.org> wrote:
>
> On Mon, Oct 16, 2023 at 10:35:16PM -0700, Song Liu wrote:
>> On Mon, Oct 16, 2023 at 8:12 PM Eric Biggers <ebiggers@kernel.org> wrote:
>>>
>>> On Mon, Oct 16, 2023 at 01:10:40PM -0700, Song Liu wrote:
>>>> On Sun, Oct 15, 2023 at 12:07 AM Eric Biggers <ebiggers@kernel.org> wrote:
>>>>>
>>>> [...]
>>>>>> + */
>>>>>> +__bpf_kfunc int bpf_get_fsverity_digest(struct file *file, struct bpf_dynptr_kern *digest_ptr)
>>>>>> +{
>>>>>> + const struct inode *inode = file_inode(file);
>>>>>> + struct fsverity_digest *arg = digest_ptr->data;
>>>>>
>>>>> What alignment is guaranteed here?
>>>>
>>>> drnptr doesn't not provide alignment guarantee for digest_ptr->data.
>>>> If we need alignment guarantee, we need to add it here.
>>>
>>> So technically it's wrong to cast it to struct fsverity_digest, then.
>>
>> We can enforce alignment here. Would __aligned(2) be sufficient?
>>
>
> Do you mean something like the following:
>
> if (!IS_ALIGNED((uintptr_t)digest_ptr->data, __alignof__(*arg)))
> return -EINVAL;
I was thinking about hard-coding the alignment requirement.
__alignof__ is much better. Thanks for the suggestion!
Song
next prev parent reply other threads:[~2023-10-17 14:16 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20231013182644.2346458-1-song@kernel.org>
[not found] ` <20231013182644.2346458-3-song@kernel.org>
2023-10-15 7:07 ` [PATCH bpf-next 2/5] bpf, fsverity: Add kfunc bpf_get_fsverity_digest Eric Biggers
2023-10-16 20:10 ` Song Liu
2023-10-17 3:12 ` Eric Biggers
2023-10-17 5:35 ` Song Liu
2023-10-17 5:46 ` Eric Biggers
2023-10-17 14:16 ` Song Liu [this message]
2023-10-17 19:50 ` Andrii Nakryiko
[not found] ` <20231013182644.2346458-6-song@kernel.org>
2023-10-17 19:08 ` [PATCH bpf-next 5/5] selftests/bpf: Add test that use fsverity and xattr to sign a file Alexei Starovoitov
2023-10-17 20:36 ` Song Liu
[not found] ` <20231013182644.2346458-2-song@kernel.org>
2023-10-17 18:58 ` [PATCH bpf-next 1/5] bpf: Add kfunc bpf_get_file_xattr Andrii Nakryiko
2023-10-17 20:31 ` Song Liu
2023-10-17 21:52 ` Andrii Nakryiko
2023-10-17 22:16 ` Song Liu
2023-10-17 22:40 ` Andrii Nakryiko
2023-10-17 22:46 ` Song Liu
2023-10-18 1:42 ` Hou Tao
2023-10-17 19:10 ` Alexei Starovoitov
2023-11-02 1:19 ` KP Singh
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