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Date:   Thu, 10 Sep 2020 21:00:10 +0100
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Matthew Wilcox <willy@infradead.org>
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Subject: Re: [RFC PATCH v9 0/3] Add introspect_access(2) (was O_MAYEXEC)
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On Thu, Sep 10, 2020 at 07:40:33PM +0100, 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()?

int lsm(int fd, const char *how, char *error, int size);

Seriously, this is "ask LSM to apply special policy to file"; let's
_not_ mess with flags, etc. for that; give it decent bandwidth
and since it's completely opaque for the rest of the kernel,
just a pass a string to be parsed by LSM as it sees fit.