linux-kernel - Re: [RFC] vfs: security: Parse dev_name before calling security_sb

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Message-ID: <56339D6E-6435-4BC4-95AC-BC2404DFF2F4@meta.com>
Date: Fri, 11 Jul 2025 23:09:54 +0000
From: Song Liu <songliubraving@...a.com>
To: Christian Brauner <brauner@...nel.org>
CC: Paul Moore <paul@...l-moore.com>, Al Viro <viro@...iv.linux.org.uk>,
        Song
 Liu <song@...nel.org>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
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Subject: Re: [RFC] vfs: security: Parse dev_name before calling
 security_sb_mount



> On Jul 11, 2025, at 2:36 AM, Christian Brauner <brauner@...nel.org> wrote:
> 
> On Thu, Jul 10, 2025 at 05:00:18PM +0000, Song Liu wrote:
>> 
>> 
>>> On Jul 10, 2025, at 4:46 AM, Christian Brauner <brauner@...nel.org> wrote:
>> 
>> [...]
>> 
>>>> Right now, we have security_sb_mount and security_move_mount, for 
>>>> syscall “mount” and “move_mount” respectively. This is confusing 
>>>> because we can also do move mount with syscall “mount”. How about 
>>>> we create 5 different security hooks:
>>>> 
>>>> security_bind_mount
>>>> security_new_mount
>>>> security_reconfigure_mount
>>>> security_remount
>>>> security_change_type_mount
>>>> 
>>>> and remove security_sb_mount. After this, we will have 6 hooks for
>>>> each type of mount (the 5 above plus security_move_mount).
>>> 
>>> I've multiple times pointed out that the current mount security hooks
>>> aren't working and basically everything in the new mount api is
>>> unsupervised from an LSM perspective.
>> 
>> To make sure I understand the comment. By “new mount api”, do you mean 
>> the code path under do_new_mount()?
> 
> fsopen()
> fsconfig()
> fsmount()
> open_tree()
> open_tree_attr()
> move_mount()
> statmount()
> listmount()
> 
> I think that's all.

Reading the code, I think we also need to cover fspick. 

Thanks,
Song