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Date: Tue, 25 Aug 2020 18:44:12 +0200 From: Borislav Petkov <bp@...en8.de> To: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com> Cc: x86@...nel.org, linux-sgx@...r.kernel.org, linux-kernel@...r.kernel.org, linux-security-module@...r.kernel.org, linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>, Matthew Wilcox <willy@...radead.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>, andriy.shevchenko@...ux.intel.com, asapek@...gle.com, cedric.xing@...el.com, chenalexchen@...gle.com, conradparker@...gle.com, cyhanish@...gle.com, dave.hansen@...el.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 v36 11/24] x86/sgx: Add SGX enclave driver On Thu, Jul 16, 2020 at 04:52:50PM +0300, Jarkko Sakkinen wrote: Just minor things below - I'm not even going to pretend I fully understand what's going on but FWICT, it looks non-threateningly ok to me. > diff --git a/arch/x86/kernel/cpu/sgx/driver.c b/arch/x86/kernel/cpu/sgx/driver.c > new file mode 100644 > index 000000000000..b52520407f5b > --- /dev/null > +++ b/arch/x86/kernel/cpu/sgx/driver.c > @@ -0,0 +1,177 @@ > +// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) > +// Copyright(c) 2016-18 Intel Corporation. > + > +#include <linux/acpi.h> > +#include <linux/miscdevice.h> > +#include <linux/mman.h> > +#include <linux/security.h> > +#include <linux/suspend.h> > +#include <asm/traps.h> > +#include "driver.h" > +#include "encl.h" > + > +MODULE_DESCRIPTION("Intel SGX Enclave Driver"); > +MODULE_AUTHOR("Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>"); > +MODULE_LICENSE("Dual BSD/GPL"); That boilerplate stuff usually goes to the end of the file. ... > +static struct sgx_encl_page *sgx_encl_load_page(struct sgx_encl *encl, > + unsigned long addr) > +{ > + struct sgx_encl_page *entry; > + unsigned int flags; > + > + /* If process was forked, VMA is still there but vm_private_data is set > + * to NULL. > + */ > + if (!encl) > + return ERR_PTR(-EFAULT); > + > + flags = atomic_read(&encl->flags); > + ^ Superfluous newline. > + if ((flags & SGX_ENCL_DEAD) || !(flags & SGX_ENCL_INITIALIZED)) > + return ERR_PTR(-EFAULT); > + > + entry = xa_load(&encl->page_array, PFN_DOWN(addr)); > + if (!entry) > + return ERR_PTR(-EFAULT); > + > + /* Page is already resident in the EPC. */ > + if (entry->epc_page) > + return entry; > + > + return ERR_PTR(-EFAULT); > +} > + > +static void sgx_mmu_notifier_release(struct mmu_notifier *mn, > + struct mm_struct *mm) > +{ > + struct sgx_encl_mm *encl_mm = > + container_of(mn, struct sgx_encl_mm, mmu_notifier); Just let it stick out. > + struct sgx_encl_mm *tmp = NULL; > + > + /* > + * The enclave itself can remove encl_mm. Note, objects can't be moved > + * off an RCU protected list, but deletion is ok. > + */ > + spin_lock(&encl_mm->encl->mm_lock); > + list_for_each_entry(tmp, &encl_mm->encl->mm_list, list) { > + if (tmp == encl_mm) { > + list_del_rcu(&encl_mm->list); > + break; > + } > + } > + spin_unlock(&encl_mm->encl->mm_lock); > + > + if (tmp == encl_mm) { > + synchronize_srcu(&encl_mm->encl->srcu); > + mmu_notifier_put(mn); > + } > +} > + > +static void sgx_mmu_notifier_free(struct mmu_notifier *mn) > +{ > + struct sgx_encl_mm *encl_mm = > + container_of(mn, struct sgx_encl_mm, mmu_notifier); Ditto. ... > +/** > + * sgx_encl_may_map() - Check if a requested VMA mapping is allowed > + * @encl: an enclave > + * @start: lower bound of the address range, inclusive > + * @end: upper bound of the address range, exclusive > + * @vm_prot_bits: requested protections of the address range > + * > + * Iterate through the enclave pages contained within [@start, @end) to verify > + * the permissions requested by @vm_prot_bits do not exceed that of any enclave > + * page to be mapped. > + * > + * Return: > + * 0 on success, > + * -EACCES if VMA permissions exceed enclave page permissions > + */ > +int sgx_encl_may_map(struct sgx_encl *encl, unsigned long start, > + unsigned long end, unsigned long vm_flags) > +{ > + unsigned long vm_prot_bits = vm_flags & (VM_READ | VM_WRITE | VM_EXEC); > + unsigned long idx_start = PFN_DOWN(start); > + unsigned long idx_end = PFN_DOWN(end - 1); > + struct sgx_encl_page *page; > + XA_STATE(xas, &encl->page_array, idx_start); > + > + /* > + * Disallow RIE tasks as their VMA permissions might conflict with the "RIE", hmm what is that? /me looks at the test Aaah, READ_IMPLIES_EXEC. Is "RIE" some widely accepted acronym I'm not aware of? > + * enclave page permissions. > + */ > + if (!!(current->personality & READ_IMPLIES_EXEC)) The "!!" is not really needed - you're in boolean context. ... -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette
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