linux-kernel - Re: [PATCH v33 11/21] x86/sgx: Linux Enclave Driver

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Message-ID: <20201027100515.GA15580@zn.tnic>
Date:   Tue, 27 Oct 2020 11:05:15 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>, x86@...nel.org,
        linux-sgx@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        Jethro Beekman <jethro@...tanix.com>,
        Haitao Huang <haitao.huang@...ux.intel.com>,
        Chunyang Hui <sanqian.hcy@...fin.com>,
        Jordan Hand <jorhand@...ux.microsoft.com>,
        Nathaniel McCallum <npmccallum@...hat.com>,
        Seth Moore <sethmo@...gle.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Suresh Siddha <suresh.b.siddha@...el.com>,
        akpm@...ux-foundation.org, andriy.shevchenko@...ux.intel.com,
        asapek@...gle.com, cedric.xing@...el.com, chenalexchen@...gle.com,
        conradparker@...gle.com, cyhanish@...gle.com,
        haitao.huang@...el.com, josh@...htriplett.org, kai.huang@...el.com,
        kai.svahn@...el.com, kmoy@...gle.com, ludloff@...gle.com,
        luto@...nel.org, nhorman@...hat.com, puiterwijk@...hat.com,
        rientjes@...gle.com, tglx@...utronix.de, yaozhangx@...gle.com
Subject: Re: [PATCH v33 11/21] x86/sgx: Linux Enclave Driver

On Mon, Oct 26, 2020 at 02:26:13PM -0700, Dave Hansen wrote:
> What were you concerned about here?  Was it how long the syscall could
> take, or that one user could exhaust all the enclave memory in one call?

More the latter. And generally, to have a sanity-check on all requests
coming from luserspace.

> Some later versions of this patch have a 1MB limit per to reduce how
> long each SGX_IOC_ENCLAVE_ADD_PAGES call spends in the kernel.  But, I'm
> not _sure_ that's what you were intending.

Yeah, that was not my main goal - rather to sanity-check user input and
impose a sane limit.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette