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Date: Tue, 27 Oct 2020 03:52:22 +0200 From: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com> To: Dave Hansen <dave.hansen@...el.com> Cc: Borislav Petkov <bp@...en8.de>, 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: > On 6/26/20 8:34 AM, Borislav Petkov wrote: > >> + if (!(atomic_read(&encl->flags) & SGX_ENCL_CREATED)) > >> + return -EINVAL; > >> + > >> + if (copy_from_user(&addp, arg, sizeof(addp))) > >> + return -EFAULT; > >> + > >> + if (!IS_ALIGNED(addp.offset, PAGE_SIZE) || > >> + !IS_ALIGNED(addp.src, PAGE_SIZE)) > >> + return -EINVAL; > >> + > >> + if (!(access_ok(addp.src, PAGE_SIZE))) > >> + return -EFAULT; > >> + > >> + if (addp.length & (PAGE_SIZE - 1)) > >> + return -EINVAL; > > How many pages are allowed? Unlimited? I'm hoping some limits are > > checked somewhere... > > 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? > > 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. The loop does check for pending signals, i.e. it is possible to interrupt it. /Jarkko
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