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Subject: Re: [RFC PATCH v9 0/3] Add introspect_access(2) (was O_MAYEXEC)
Cc:     James Morris <jmorris@namei.org>,
        Matthew Wilcox <willy@infradead.org>,
        Mimi Zohar <zohar@linux.ibm.com>, linux-kernel@vger.kernel.org,
        Aleksa Sarai <cyphar@cyphar.com>,
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 <alpine.LRH.2.21.2009121019050.17638@namei.org>
To:     Arnd Bergmann <arnd@arndb.de>,
        Michael Kerrisk <mtk.manpages@gmail.com>,
        linux-api@vger.kernel.org
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Date:   Mon, 14 Sep 2020 18:43:17 +0200
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Arnd and Michael,

What do you think of "should_faccessat" or "entrusted_faccessat" for
this new system call?


On 12/09/2020 02:28, James Morris wrote:
> On Thu, 10 Sep 2020, Matthew Wilcox wrote:
> 
>> On Thu, Sep 10, 2020 at 08:38:21PM +0200, Mickaël Salaün wrote:
>>> There is also the use case of noexec mounts and file permissions. From
>>> user space point of view, it doesn't matter which kernel component is in
>>> charge of defining the policy. The syscall should then not be tied with
>>> a verification/integrity/signature/appraisal vocabulary, but simply an
>>> access control one.
>>
>> permission()?
>>
> 
> The caller is not asking the kernel to grant permission, it's asking 
> "SHOULD I access this file?"
> 
> The caller doesn't know, for example, if the script file it's about to 
> execute has been signed, or if it's from a noexec mount. It's asking the 
> kernel, which does know. (Note that this could also be extended to reading 
> configuration files).
> 
> How about: should_faccessat ?
> 

Sounds good to me.