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From: Matthew Wilcox <willy@infradead.org>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: x86@kernel.org, linux-sgx@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-security-module@vger.kernel.org, linux-mm@kvack.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Jethro Beekman <jethro@fortanix.com>,
	Haitao Huang <haitao.huang@linux.intel.com>,
	Chunyang Hui <sanqian.hcy@antfin.com>,
	Jordan Hand <jorhand@linux.microsoft.com>,
	Nathaniel McCallum <npmccallum@redhat.com>,
	Seth Moore <sethmo@google.com>,
	Darren Kenny <darren.kenny@oracle.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Suresh Siddha <suresh.b.siddha@intel.com>,
	andriy.shevchenko@linux.intel.com, asapek@google.com,
	bp@alien8.de, cedric.xing@intel.com, chenalexchen@google.com,
	conradparker@google.com, cyhanish@google.com,
	dave.hansen@intel.com, haitao.huang@intel.com,
	kai.huang@intel.com, kai.svahn@intel.com, kmoy@google.com,
	ludloff@google.com, luto@kernel.org, nhorman@redhat.com,
	puiterwijk@redhat.com, rientjes@google.com, tglx@linutronix.de,
	yaozhangx@google.com, mikko.ylinen@intel.com
Subject: Re: [PATCH v39 11/24] x86/sgx: Add SGX enclave driver
Date: Sat, 3 Oct 2020 20:54:40 +0100
Message-ID: <20201003195440.GD20115@casper.infradead.org> (raw)
In-Reply-To: <20201003045059.665934-12-jarkko.sakkinen@linux.intel.com>

On Sat, Oct 03, 2020 at 07:50:46AM +0300, Jarkko Sakkinen wrote:
> +	XA_STATE(xas, &encl->page_array, idx_start);
> +
> +	/*
> +	 * Disallow READ_IMPLIES_EXEC tasks as their VMA permissions might
> +	 * conflict with the enclave page permissions.
> +	 */
> +	if (current->personality & READ_IMPLIES_EXEC)
> +		return -EACCES;
> +
> +	xas_for_each(&xas, page, idx_end)
> +		if (!page || (~page->vm_max_prot_bits & vm_prot_bits))
> +			return -EACCES;

You're iterating the array without holding any lock that the XArray knows
about.  If you're OK with another thread adding/removing pages behind your
back, or there's a higher level lock (the mmap_sem?) protecting the XArray
from being modified while you walk it, then hold the rcu_read_lock()
while walking the array.  Otherwise you can prevent modification by
calling xas_lock(&xas) and xas_unlock()..

> +	return 0;
> +}
> +
> +static int sgx_vma_mprotect(struct vm_area_struct *vma,
> +			    struct vm_area_struct **pprev, unsigned long start,
> +			    unsigned long end, unsigned long newflags)
> +{
> +	int ret;
> +
> +	ret = sgx_encl_may_map(vma->vm_private_data, start, end, newflags);
> +	if (ret)
> +		return ret;
> +
> +	return mprotect_fixup(vma, pprev, start, end, newflags);
> +}
> +
> +const struct vm_operations_struct sgx_vm_ops = {
> +	.open = sgx_vma_open,
> +	.fault = sgx_vma_fault,
> +	.mprotect = sgx_vma_mprotect,
> +};
> +
> +/**
> + * sgx_encl_find - find an enclave
> + * @mm:		mm struct of the current process
> + * @addr:	address in the ELRANGE
> + * @vma:	the resulting VMA
> + *
> + * Find an enclave identified by the given address. Give back a VMA that is
> + * part of the enclave and located in that address. The VMA is given back if it
> + * is a proper enclave VMA even if an &sgx_encl instance does not exist yet
> + * (enclave creation has not been performed).
> + *
> + * Return:
> + *   0 on success,
> + *   -EINVAL if an enclave was not found,
> + *   -ENOENT if the enclave has not been created yet
> + */
> +int sgx_encl_find(struct mm_struct *mm, unsigned long addr,
> +		  struct vm_area_struct **vma)
> +{
> +	struct vm_area_struct *result;
> +	struct sgx_encl *encl;
> +
> +	result = find_vma(mm, addr);
> +	if (!result || result->vm_ops != &sgx_vm_ops || addr < result->vm_start)
> +		return -EINVAL;
> +
> +	encl = result->vm_private_data;
> +	*vma = result;
> +
> +	return encl ? 0 : -ENOENT;
> +}
> +
> +/**
> + * sgx_encl_destroy() - destroy enclave resources
> + * @encl:	an enclave pointer
> + */
> +void sgx_encl_destroy(struct sgx_encl *encl)
> +{
> +	struct sgx_encl_page *entry;
> +	unsigned long index;
> +
> +	atomic_or(SGX_ENCL_DEAD, &encl->flags);
> +
> +	xa_for_each(&encl->page_array, index, entry) {
> +		if (entry->epc_page) {
> +			sgx_free_epc_page(entry->epc_page);
> +			encl->secs_child_cnt--;
> +			entry->epc_page = NULL;
> +		}
> +
> +		kfree(entry);
> +	}
> +
> +	xa_destroy(&encl->page_array);
> +
> +	if (!encl->secs_child_cnt && encl->secs.epc_page) {
> +		sgx_free_epc_page(encl->secs.epc_page);
> +		encl->secs.epc_page = NULL;
> +	}
> +}
> +
> +/**
> + * sgx_encl_release - Destroy an enclave instance
> + * @kref:	address of a kref inside &sgx_encl
> + *
> + * Used together with kref_put(). Frees all the resources associated with the
> + * enclave and the instance itself.
> + */
> +void sgx_encl_release(struct kref *ref)
> +{
> +	struct sgx_encl *encl = container_of(ref, struct sgx_encl, refcount);
> +
> +	sgx_encl_destroy(encl);
> +
> +	if (encl->backing)
> +		fput(encl->backing);
> +
> +	cleanup_srcu_struct(&encl->srcu);
> +
> +	WARN_ON_ONCE(!list_empty(&encl->mm_list));
> +
> +	/* Detect EPC page leak's. */
> +	WARN_ON_ONCE(encl->secs_child_cnt);
> +	WARN_ON_ONCE(encl->secs.epc_page);
> +
> +	kfree(encl);
> +}
> diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h
> new file mode 100644
> index 000000000000..8ff445476657
> --- /dev/null
> +++ b/arch/x86/kernel/cpu/sgx/encl.h
> @@ -0,0 +1,85 @@
> +/* SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) */
> +/**
> + * Copyright(c) 2016-19 Intel Corporation.
> + */
> +#ifndef _X86_ENCL_H
> +#define _X86_ENCL_H
> +
> +#include <linux/cpumask.h>
> +#include <linux/kref.h>
> +#include <linux/list.h>
> +#include <linux/mm_types.h>
> +#include <linux/mmu_notifier.h>
> +#include <linux/mutex.h>
> +#include <linux/notifier.h>
> +#include <linux/srcu.h>
> +#include <linux/workqueue.h>
> +#include <linux/xarray.h>
> +#include "sgx.h"
> +
> +/**
> + * enum sgx_encl_page_desc - defines bits for an enclave page's descriptor
> + * %SGX_ENCL_PAGE_ADDR_MASK:		Holds the virtual address of the page.
> + *
> + * The page address for SECS is zero and is used by the subsystem to recognize
> + * the SECS page.
> + */
> +enum sgx_encl_page_desc {
> +	/* Bits 11:3 are available when the page is not swapped. */
> +	SGX_ENCL_PAGE_ADDR_MASK		= PAGE_MASK,
> +};
> +
> +#define SGX_ENCL_PAGE_ADDR(page) \
> +	((page)->desc & SGX_ENCL_PAGE_ADDR_MASK)
> +
> +struct sgx_encl_page {
> +	unsigned long desc;
> +	unsigned long vm_max_prot_bits;
> +	struct sgx_epc_page *epc_page;
> +	struct sgx_encl *encl;
> +};
> +
> +enum sgx_encl_flags {
> +	SGX_ENCL_CREATED	= BIT(0),
> +	SGX_ENCL_INITIALIZED	= BIT(1),
> +	SGX_ENCL_DEBUG		= BIT(2),
> +	SGX_ENCL_DEAD		= BIT(3),
> +	SGX_ENCL_IOCTL		= BIT(4),
> +};
> +
> +struct sgx_encl_mm {
> +	struct sgx_encl *encl;
> +	struct mm_struct *mm;
> +	struct list_head list;
> +	struct mmu_notifier mmu_notifier;
> +};
> +
> +struct sgx_encl {
> +	atomic_t flags;
> +	unsigned int page_cnt;
> +	unsigned int secs_child_cnt;
> +	struct mutex lock;
> +	struct list_head mm_list;
> +	spinlock_t mm_lock;
> +	struct file *backing;
> +	struct kref refcount;
> +	struct srcu_struct srcu;
> +	unsigned long base;
> +	unsigned long size;
> +	unsigned long ssaframesize;
> +	struct xarray page_array;
> +	struct sgx_encl_page secs;
> +	cpumask_t cpumask;
> +};
> +
> +extern const struct vm_operations_struct sgx_vm_ops;
> +
> +int sgx_encl_find(struct mm_struct *mm, unsigned long addr,
> +		  struct vm_area_struct **vma);
> +void sgx_encl_destroy(struct sgx_encl *encl);
> +void sgx_encl_release(struct kref *ref);
> +int sgx_encl_mm_add(struct sgx_encl *encl, struct mm_struct *mm);
> +int sgx_encl_may_map(struct sgx_encl *encl, unsigned long start,
> +		     unsigned long end, unsigned long vm_flags);
> +
> +#endif /* _X86_ENCL_H */
> diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
> index 97c6895fb6c9..4137254fb29e 100644
> --- a/arch/x86/kernel/cpu/sgx/main.c
> +++ b/arch/x86/kernel/cpu/sgx/main.c
> @@ -9,6 +9,8 @@
>  #include <linux/sched/mm.h>
>  #include <linux/sched/signal.h>
>  #include <linux/slab.h>
> +#include "driver.h"
> +#include "encl.h"
>  #include "encls.h"
>  
>  struct sgx_epc_section sgx_epc_sections[SGX_MAX_EPC_SECTIONS];
> @@ -260,6 +262,8 @@ static bool __init sgx_page_cache_init(void)
>  
>  static void __init sgx_init(void)
>  {
> +	int ret;
> +
>  	if (!boot_cpu_has(X86_FEATURE_SGX))
>  		return;
>  
> @@ -269,8 +273,15 @@ static void __init sgx_init(void)
>  	if (!sgx_page_reclaimer_init())
>  		goto err_page_cache;
>  
> +	ret = sgx_drv_init();
> +	if (ret)
> +		goto err_kthread;
> +
>  	return;
>  
> +err_kthread:
> +	kthread_stop(ksgxswapd_tsk);
> +
>  err_page_cache:
>  	sgx_page_cache_teardown();
>  }
> -- 
> 2.25.1
> 

  parent reply index

Thread overview: 117+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-03  4:50 [PATCH v39 00/24] Intel SGX foundations Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 01/24] x86/cpufeatures: x86/msr: Add Intel SGX hardware bits Jarkko Sakkinen
2020-10-19 14:10   ` Dave Hansen
2020-10-19 17:49     ` Sean Christopherson
2020-10-03  4:50 ` [PATCH v39 02/24] x86/cpufeatures: x86/msr: Add Intel SGX Launch Control " Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 03/24] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 04/24] x86/sgx: Add SGX microarchitectural data structures Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 05/24] x86/sgx: Add wrappers for ENCLS leaf functions Jarkko Sakkinen
2020-10-19 14:30   ` Dave Hansen
2020-10-19 17:38     ` Sean Christopherson
2020-10-19 17:48       ` Dave Hansen
2020-10-19 17:53         ` Sean Christopherson
2020-10-19 17:58           ` Dave Hansen
2020-10-03  4:50 ` [PATCH v39 06/24] x86/cpu/intel: Detect SGX support Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 07/24] x86/cpu/intel: Add nosgx kernel parameter Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 08/24] x86/sgx: Initialize metadata for Enclave Page Cache (EPC) sections Jarkko Sakkinen
2020-10-19  8:45   ` Jarkko Sakkinen
2020-10-19 12:39     ` Borislav Petkov
2020-10-23  9:01       ` Jarkko Sakkinen
2020-10-19 13:40     ` Dave Hansen
2020-10-23  9:03       ` Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 09/24] x86/sgx: Add __sgx_alloc_epc_page() and sgx_free_epc_page() Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 10/24] mm: Add 'mprotect' hook to struct vm_operations_struct Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 11/24] x86/sgx: Add SGX enclave driver Jarkko Sakkinen
2020-10-03 14:39   ` Greg KH
2020-10-04 14:32     ` Jarkko Sakkinen
2020-10-04 15:01       ` Jarkko Sakkinen
2020-10-05  9:42       ` Greg KH
2020-10-05 12:42         ` Jarkko Sakkinen
2020-10-07 18:09           ` Haitao Huang
2020-10-07 19:26             ` Greg KH
2020-10-09  6:44               ` Jarkko Sakkinen
2020-10-14 20:16                 ` Dave Hansen
2020-10-05  8:45     ` Christoph Hellwig
2020-10-05 11:42       ` Jarkko Sakkinen
2020-10-05 11:50         ` Greg KH
2020-10-05 14:23           ` Jarkko Sakkinen
2020-10-05 15:02             ` Greg KH
2020-10-05 16:40               ` Dave Hansen
2020-10-05 20:02                 ` Jarkko Sakkinen
2020-10-09  7:10     ` Pavel Machek
2020-10-09  7:21       ` Greg KH
2020-10-09  8:21         ` Pavel Machek
2020-10-03 19:54   ` Matthew Wilcox [this message]
2020-10-04 21:50     ` Jarkko Sakkinen
2020-10-04 22:02       ` Jarkko Sakkinen
2020-10-04 22:27       ` Matthew Wilcox
2020-10-04 23:41         ` Jarkko Sakkinen
2020-10-05  1:30           ` Matthew Wilcox
2020-10-05  3:06             ` Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 12/24] x86/sgx: Add SGX_IOC_ENCLAVE_CREATE Jarkko Sakkinen
2020-10-16 17:07   ` Dave Hansen
2020-10-18  4:26     ` Jarkko Sakkinen
2020-10-19 20:21       ` Dave Hansen
2020-10-19 20:48         ` Sean Christopherson
2020-10-03  4:50 ` [PATCH v39 13/24] x86/sgx: Add SGX_IOC_ENCLAVE_ADD_PAGES Jarkko Sakkinen
2020-10-16 21:25   ` Dave Hansen
2020-10-18  5:03     ` Jarkko Sakkinen
2020-10-19  7:03       ` Jarkko Sakkinen
2020-10-19 20:48       ` Dave Hansen
2020-10-19 21:15         ` Sean Christopherson
2020-10-19 21:44           ` Dave Hansen
2020-10-23 10:11             ` Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 14/24] x86/sgx: Add SGX_IOC_ENCLAVE_INIT Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 15/24] x86/sgx: Add SGX_IOC_ENCLAVE_PROVISION Jarkko Sakkinen
2020-10-20 15:48   ` Dave Hansen
2020-10-23 10:14     ` Jarkko Sakkinen
2020-10-20 21:19   ` Dave Hansen
2020-10-23 10:17     ` Jarkko Sakkinen
2020-10-23 14:19       ` Dave Hansen
2020-10-24 11:34         ` Jarkko Sakkinen
2020-10-24 15:47           ` Andy Lutomirski
2020-10-24 20:23             ` Jarkko Sakkinen
2020-10-27 10:38               ` Dr. Greg
2020-10-23 14:23       ` Jethro Beekman
2020-10-24 11:40         ` Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 16/24] x86/sgx: Add a page reclaimer Jarkko Sakkinen
2020-10-03  5:22   ` Haitao Huang
2020-10-03 13:32     ` Jarkko Sakkinen
2020-10-03 18:23       ` Haitao Huang
2020-10-04 22:39         ` Jarkko Sakkinen
2020-10-07 17:25           ` Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 17/24] x86/sgx: Add ptrace() support for the SGX driver Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 18/24] x86/vdso: Add support for exception fixup in vDSO functions Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 19/24] x86/fault: Add helper function to sanitize error code Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 20/24] x86/traps: Attempt to fixup exceptions in vDSO before signaling Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 21/24] x86/vdso: Implement a vDSO for Intel SGX enclave call Jarkko Sakkinen
2020-10-06  2:57   ` Sean Christopherson
2020-10-06  8:30     ` Jethro Beekman
2020-10-06 15:15       ` Sean Christopherson
2020-10-06 17:28         ` Jarkko Sakkinen
2020-10-06 23:21           ` Sean Christopherson
2020-10-07  0:22             ` Jarkko Sakkinen
2020-10-07  1:17               ` Sean Christopherson
2020-10-07  3:14                 ` Jarkko Sakkinen
2020-10-07  4:34                   ` Sean Christopherson
2020-10-07  7:39                     ` Jarkko Sakkinen
2020-10-07  8:04                       ` Jarkko Sakkinen
2020-10-07 15:25                       ` Sean Christopherson
2020-10-07 17:08                         ` Jarkko Sakkinen
2020-10-07 17:13                           ` Jarkko Sakkinen
2020-10-06 15:49       ` Jarkko Sakkinen
2020-10-06 15:36     ` Jarkko Sakkinen
2020-10-06 21:39     ` Jarkko Sakkinen
2020-10-07  0:23       ` Jarkko Sakkinen
2020-10-17  1:48   ` Andy Lutomirski
2020-10-17 21:02     ` Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 22/24] selftests/x86: Add a selftest for SGX Jarkko Sakkinen
2020-10-12 16:50   ` Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 23/24] docs: x86/sgx: Document SGX micro architecture and kernel internals Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 24/24] x86/sgx: Update MAINTAINERS Jarkko Sakkinen
2020-10-16 21:04   ` Dave Hansen
2020-10-18  4:27     ` Jarkko Sakkinen
2020-10-03 14:32 ` [PATCH v39 00/24] Intel SGX foundations Greg KH
2020-10-03 14:53   ` Jarkko Sakkinen
2020-10-15 19:06 ` Dave Hansen
2020-10-17 20:43   ` Jarkko Sakkinen

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