[PATCH v33 11/21] x86/sgx: Linux Enclave Driver

[PATCH v33 11/21] x86/sgx: Linux Enclave Driver

[Jarkko Sakkinen]

Intel Software Guard eXtensions (SGX) is a set of CPU instructions that
can be used by applications to set aside private regions of code and
data. The code outside the SGX hosted software entity is disallowed to
access the memory inside the enclave enforced by the CPU. We call these
entities as enclaves.

This commit implements a driver that provides an ioctl API to construct
and run enclaves. Enclaves are constructed from pages residing in
reserved physical memory areas. The contents of these pages can only be
accessed when they are mapped as part of an enclave, by a hardware
thread running inside the enclave.

The starting state of an enclave consists of a fixed measured set of
pages that are copied to the EPC during the construction process by
using ENCLS leaf functions and Software Enclave Control Structure (SECS)
that defines the enclave properties.

Enclave are constructed by using ENCLS leaf functions ECREATE, EADD and
EINIT. ECREATE initializes SECS, EADD copies pages from system memory to
the EPC and EINIT check a given signed measurement and moves the enclave
into a state ready for execution.

An initialized enclave can only be accessed through special Thread Control
Structure (TCS) pages by using ENCLU (ring-3 only) leaf EENTER.  This leaf
function converts a thread into enclave mode and continues the execution in
the offset defined by the TCS provided to EENTER. An enclave is exited
through syscall, exception, interrupts or by explicitly calling another
ENCLU leaf EEXIT.

The permissions, which enclave page is added will set the limit for maximum
permissions that can be set for mmap() and mprotect(). This will
effectively allow to build different security schemes between producers and
consumers of enclaves. Later on we can increase granularity with LSM hooks
for page addition (i.e. for producers) and mapping of the enclave (i.e. for
consumers)

Cc: linux-security-module@vger.kernel.org
Acked-by: Jethro Beekman <jethro@fortanix.com>
Tested-by: Jethro Beekman <jethro@fortanix.com>
Tested-by: Haitao Huang <haitao.huang@linux.intel.com>
Tested-by: Chunyang Hui <sanqian.hcy@antfin.com>
Tested-by: Jordan Hand <jorhand@linux.microsoft.com>
Tested-by: Nathaniel McCallum <npmccallum@redhat.com>
Tested-by: Seth Moore <sethmo@google.com>
Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Co-developed-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
 .../userspace-api/ioctl/ioctl-number.rst      |   1 +
 arch/x86/include/uapi/asm/sgx.h               |  66 ++
 arch/x86/kernel/cpu/sgx/Makefile              |   3 +
 arch/x86/kernel/cpu/sgx/driver.c              | 194 +++++
 arch/x86/kernel/cpu/sgx/driver.h              |  30 +
 arch/x86/kernel/cpu/sgx/encl.c                | 335 +++++++++
 arch/x86/kernel/cpu/sgx/encl.h                |  87 +++
 arch/x86/kernel/cpu/sgx/ioctl.c               | 706 ++++++++++++++++++
 arch/x86/kernel/cpu/sgx/main.c                |  11 +
 9 files changed, 1433 insertions(+)
 create mode 100644 arch/x86/include/uapi/asm/sgx.h
 create mode 100644 arch/x86/kernel/cpu/sgx/driver.c
 create mode 100644 arch/x86/kernel/cpu/sgx/driver.h
 create mode 100644 arch/x86/kernel/cpu/sgx/encl.c
 create mode 100644 arch/x86/kernel/cpu/sgx/encl.h
 create mode 100644 arch/x86/kernel/cpu/sgx/ioctl.c

diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
index 59472cd6a11d..35f713e3a267 100644
--- a/Documentation/userspace-api/ioctl/ioctl-number.rst
+++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
@@ -323,6 +323,7 @@ Code  Seq#    Include File                                           Comments
                                                                      <mailto:tlewis@mindspring.com>
 0xA3  90-9F  linux/dtlk.h
 0xA4  00-1F  uapi/linux/tee.h                                        Generic TEE subsystem
+0xA4  00-1F  uapi/asm/sgx.h                                          Intel SGX subsystem (a legit conflict as TEE and SGX do not co-exist)
 0xAA  00-3F  linux/uapi/linux/userfaultfd.h
 0xAB  00-1F  linux/nbd.h
 0xAC  00-1F  linux/raw.h
diff --git a/arch/x86/include/uapi/asm/sgx.h b/arch/x86/include/uapi/asm/sgx.h
new file mode 100644
index 000000000000..5edb08ab8fd0
--- /dev/null
+++ b/arch/x86/include/uapi/asm/sgx.h
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) WITH Linux-syscall-note */
+/*
+ * Copyright(c) 2016-19 Intel Corporation.
+ */
+#ifndef _UAPI_ASM_X86_SGX_H
+#define _UAPI_ASM_X86_SGX_H
+
+#include <linux/types.h>
+#include <linux/ioctl.h>
+
+/**
+ * enum sgx_epage_flags - page control flags
+ * %SGX_PAGE_MEASURE:	Measure the page contents with a sequence of
+ *			ENCLS[EEXTEND] operations.
+ */
+enum sgx_page_flags {
+	SGX_PAGE_MEASURE	= 0x01,
+};
+
+#define SGX_MAGIC 0xA4
+
+#define SGX_IOC_ENCLAVE_CREATE \
+	_IOW(SGX_MAGIC, 0x00, struct sgx_enclave_create)
+#define SGX_IOC_ENCLAVE_ADD_PAGES \
+	_IOWR(SGX_MAGIC, 0x01, struct sgx_enclave_add_pages)
+#define SGX_IOC_ENCLAVE_INIT \
+	_IOW(SGX_MAGIC, 0x02, struct sgx_enclave_init)
+
+/**
+ * struct sgx_enclave_create - parameter structure for the
+ *                             %SGX_IOC_ENCLAVE_CREATE ioctl
+ * @src:	address for the SECS page data
+ */
+struct sgx_enclave_create  {
+	__u64	src;
+};
+
+/**
+ * struct sgx_enclave_add_pages - parameter structure for the
+ *                                %SGX_IOC_ENCLAVE_ADD_PAGE ioctl
+ * @src:	start address for the page data
+ * @offset:	starting page offset
+ * @length:	length of the data (multiple of the page size)
+ * @secinfo:	address for the SECINFO data
+ * @flags:	page control flags
+ * @count:	number of bytes added (multiple of the page size)
+ */
+struct sgx_enclave_add_pages {
+	__u64	src;
+	__u64	offset;
+	__u64	length;
+	__u64	secinfo;
+	__u64	flags;
+	__u64	count;
+};
+
+/**
+ * struct sgx_enclave_init - parameter structure for the
+ *                           %SGX_IOC_ENCLAVE_INIT ioctl
+ * @sigstruct:	address for the SIGSTRUCT data
+ */
+struct sgx_enclave_init {
+	__u64 sigstruct;
+};
+
+#endif /* _UAPI_ASM_X86_SGX_H */
diff --git a/arch/x86/kernel/cpu/sgx/Makefile b/arch/x86/kernel/cpu/sgx/Makefile
index 79510ce01b3b..91d3dc784a29 100644
--- a/arch/x86/kernel/cpu/sgx/Makefile
+++ b/arch/x86/kernel/cpu/sgx/Makefile
@@ -1,2 +1,5 @@
 obj-y += \
+	driver.o \
+	encl.o \
+	ioctl.o \
 	main.o
diff --git a/arch/x86/kernel/cpu/sgx/driver.c b/arch/x86/kernel/cpu/sgx/driver.c
new file mode 100644
index 000000000000..b4aa7b9f8376
--- /dev/null
+++ b/arch/x86/kernel/cpu/sgx/driver.c
@@ -0,0 +1,194 @@
+// 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@linux.intel.com>");
+MODULE_LICENSE("Dual BSD/GPL");
+
+u64 sgx_encl_size_max_32;
+u64 sgx_encl_size_max_64;
+u32 sgx_misc_reserved_mask;
+u64 sgx_attributes_reserved_mask;
+u64 sgx_xfrm_reserved_mask = ~0x3;
+u32 sgx_xsave_size_tbl[64];
+
+static int sgx_open(struct inode *inode, struct file *file)
+{
+	struct sgx_encl *encl;
+	int ret;
+
+	encl = kzalloc(sizeof(*encl), GFP_KERNEL);
+	if (!encl)
+		return -ENOMEM;
+
+	atomic_set(&encl->flags, 0);
+	kref_init(&encl->refcount);
+	INIT_RADIX_TREE(&encl->page_tree, GFP_KERNEL);
+	mutex_init(&encl->lock);
+	INIT_LIST_HEAD(&encl->mm_list);
+	spin_lock_init(&encl->mm_lock);
+
+	ret = init_srcu_struct(&encl->srcu);
+	if (ret) {
+		kfree(encl);
+		return ret;
+	}
+
+	file->private_data = encl;
+
+	return 0;
+}
+
+static int sgx_release(struct inode *inode, struct file *file)
+{
+	struct sgx_encl *encl = file->private_data;
+	struct sgx_encl_mm *encl_mm;
+
+	for ( ; ; )  {
+		spin_lock(&encl->mm_lock);
+
+		if (list_empty(&encl->mm_list)) {
+			encl_mm = NULL;
+		} else {
+			encl_mm = list_first_entry(&encl->mm_list,
+						   struct sgx_encl_mm, list);
+			list_del_rcu(&encl_mm->list);
+		}
+
+		spin_unlock(&encl->mm_lock);
+
+		/* The list is empty, ready to go. */
+		if (!encl_mm)
+			break;
+
+		synchronize_srcu(&encl->srcu);
+		mmu_notifier_unregister(&encl_mm->mmu_notifier, encl_mm->mm);
+		kfree(encl_mm);
+	};
+
+	mutex_lock(&encl->lock);
+	atomic_or(SGX_ENCL_DEAD, &encl->flags);
+	mutex_unlock(&encl->lock);
+
+	kref_put(&encl->refcount, sgx_encl_release);
+	return 0;
+}
+
+#ifdef CONFIG_COMPAT
+static long sgx_compat_ioctl(struct file *filep, unsigned int cmd,
+			      unsigned long arg)
+{
+	return sgx_ioctl(filep, cmd, arg);
+}
+#endif
+
+static int sgx_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct sgx_encl *encl = file->private_data;
+	int ret;
+
+	ret = sgx_encl_may_map(encl, vma->vm_start, vma->vm_end,
+			       vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC));
+	if (ret)
+		return ret;
+
+	ret = sgx_encl_mm_add(encl, vma->vm_mm);
+	if (ret)
+		return ret;
+
+	vma->vm_ops = &sgx_vm_ops;
+	vma->vm_flags |= VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP | VM_IO;
+	vma->vm_private_data = encl;
+
+	return 0;
+}
+
+static unsigned long sgx_get_unmapped_area(struct file *file,
+					   unsigned long addr,
+					   unsigned long len,
+					   unsigned long pgoff,
+					   unsigned long flags)
+{
+	if (flags & MAP_PRIVATE)
+		return -EINVAL;
+
+	if (flags & MAP_FIXED)
+		return addr;
+
+	return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
+}
+
+static const struct file_operations sgx_encl_fops = {
+	.owner			= THIS_MODULE,
+	.open			= sgx_open,
+	.release		= sgx_release,
+	.unlocked_ioctl		= sgx_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl		= sgx_compat_ioctl,
+#endif
+	.mmap			= sgx_mmap,
+	.get_unmapped_area	= sgx_get_unmapped_area,
+};
+
+const struct file_operations sgx_provision_fops = {
+	.owner			= THIS_MODULE,
+};
+
+static struct miscdevice sgx_dev_enclave = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "enclave",
+	.nodename = "sgx/enclave",
+	.fops = &sgx_encl_fops,
+};
+
+int __init sgx_drv_init(void)
+{
+	unsigned int eax, ebx, ecx, edx;
+	u64 attr_mask, xfrm_mask;
+	int ret;
+	int i;
+
+	if (!boot_cpu_has(X86_FEATURE_SGX_LC)) {
+		pr_info("The public key MSRs are not writable.\n");
+		return -ENODEV;
+	}
+
+	cpuid_count(SGX_CPUID, 0, &eax, &ebx, &ecx, &edx);
+	sgx_misc_reserved_mask = ~ebx | SGX_MISC_RESERVED_MASK;
+	sgx_encl_size_max_64 = 1ULL << ((edx >> 8) & 0xFF);
+	sgx_encl_size_max_32 = 1ULL << (edx & 0xFF);
+
+	cpuid_count(SGX_CPUID, 1, &eax, &ebx, &ecx, &edx);
+
+	attr_mask = (((u64)ebx) << 32) + (u64)eax;
+	sgx_attributes_reserved_mask = ~attr_mask | SGX_ATTR_RESERVED_MASK;
+
+	if (boot_cpu_has(X86_FEATURE_OSXSAVE)) {
+		xfrm_mask = (((u64)edx) << 32) + (u64)ecx;
+
+		for (i = 2; i < 64; i++) {
+			cpuid_count(0x0D, i, &eax, &ebx, &ecx, &edx);
+			if ((1 << i) & xfrm_mask)
+				sgx_xsave_size_tbl[i] = eax + ebx;
+		}
+
+		sgx_xfrm_reserved_mask = ~xfrm_mask;
+	}
+
+	ret = misc_register(&sgx_dev_enclave);
+	if (ret) {
+		pr_err("Creating /dev/sgx/enclave failed with %d.\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
diff --git a/arch/x86/kernel/cpu/sgx/driver.h b/arch/x86/kernel/cpu/sgx/driver.h
new file mode 100644
index 000000000000..e4063923115b
--- /dev/null
+++ b/arch/x86/kernel/cpu/sgx/driver.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) */
+#ifndef __ARCH_SGX_DRIVER_H__
+#define __ARCH_SGX_DRIVER_H__
+
+#include <crypto/hash.h>
+#include <linux/kref.h>
+#include <linux/mmu_notifier.h>
+#include <linux/radix-tree.h>
+#include <linux/rwsem.h>
+#include <linux/sched.h>
+#include <linux/workqueue.h>
+#include <uapi/asm/sgx.h>
+#include "sgx.h"
+
+#define SGX_EINIT_SPIN_COUNT	20
+#define SGX_EINIT_SLEEP_COUNT	50
+#define SGX_EINIT_SLEEP_TIME	20
+
+extern u64 sgx_encl_size_max_32;
+extern u64 sgx_encl_size_max_64;
+extern u32 sgx_misc_reserved_mask;
+extern u64 sgx_attributes_reserved_mask;
+extern u64 sgx_xfrm_reserved_mask;
+extern u32 sgx_xsave_size_tbl[64];
+
+long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg);
+
+int sgx_drv_init(void);
+
+#endif /* __ARCH_X86_SGX_DRIVER_H__ */
diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
new file mode 100644
index 000000000000..939b2faa185a
--- /dev/null
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -0,0 +1,335 @@
+// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
+// Copyright(c) 2016-18 Intel Corporation.
+
+#include <linux/lockdep.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/shmem_fs.h>
+#include <linux/suspend.h>
+#include <linux/sched/mm.h>
+#include "arch.h"
+#include "encl.h"
+#include "encls.h"
+#include "sgx.h"
+
+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);
+
+	if ((flags & SGX_ENCL_DEAD) || !(flags & SGX_ENCL_INITIALIZED))
+		return ERR_PTR(-EFAULT);
+
+	entry = radix_tree_lookup(&encl->page_tree, addr >> PAGE_SHIFT);
+	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);
+	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);
+
+	kfree(encl_mm);
+}
+
+static const struct mmu_notifier_ops sgx_mmu_notifier_ops = {
+	.release		= sgx_mmu_notifier_release,
+	.free_notifier		= sgx_mmu_notifier_free,
+};
+
+static struct sgx_encl_mm *sgx_encl_find_mm(struct sgx_encl *encl,
+					    struct mm_struct *mm)
+{
+	struct sgx_encl_mm *encl_mm = NULL;
+	struct sgx_encl_mm *tmp;
+	int idx;
+
+	idx = srcu_read_lock(&encl->srcu);
+
+	list_for_each_entry_rcu(tmp, &encl->mm_list, list) {
+		if (tmp->mm == mm) {
+			encl_mm = tmp;
+			break;
+		}
+	}
+
+	srcu_read_unlock(&encl->srcu, idx);
+
+	return encl_mm;
+}
+
+int sgx_encl_mm_add(struct sgx_encl *encl, struct mm_struct *mm)
+{
+	struct sgx_encl_mm *encl_mm;
+	int ret;
+
+	/* mm_list can be accessed only by a single thread at a time. */
+	mmap_assert_write_locked(mm);
+
+	if (atomic_read(&encl->flags) & SGX_ENCL_DEAD)
+		return -EINVAL;
+
+	/*
+	 * mm_structs are kept on mm_list until the mm or the enclave dies,
+	 * i.e. once an mm is off the list, it's gone for good, therefore it's
+	 * impossible to get a false positive on @mm due to a stale mm_list.
+	 */
+	if (sgx_encl_find_mm(encl, mm))
+		return 0;
+
+	encl_mm = kzalloc(sizeof(*encl_mm), GFP_KERNEL);
+	if (!encl_mm)
+		return -ENOMEM;
+
+	encl_mm->encl = encl;
+	encl_mm->mm = mm;
+	encl_mm->mmu_notifier.ops = &sgx_mmu_notifier_ops;
+
+	ret = __mmu_notifier_register(&encl_mm->mmu_notifier, mm);
+	if (ret) {
+		kfree(encl_mm);
+		return ret;
+	}
+
+	spin_lock(&encl->mm_lock);
+	list_add_rcu(&encl_mm->list, &encl->mm_list);
+	spin_unlock(&encl->mm_lock);
+
+	return 0;
+}
+
+static void sgx_vma_open(struct vm_area_struct *vma)
+{
+	struct sgx_encl *encl = vma->vm_private_data;
+
+	if (!encl)
+		return;
+
+	if (sgx_encl_mm_add(encl, vma->vm_mm))
+		vma->vm_private_data = NULL;
+}
+
+static unsigned int sgx_vma_fault(struct vm_fault *vmf)
+{
+	unsigned long addr = (unsigned long)vmf->address;
+	struct vm_area_struct *vma = vmf->vma;
+	struct sgx_encl *encl = vma->vm_private_data;
+	struct sgx_encl_page *entry;
+	int ret = VM_FAULT_NOPAGE;
+	unsigned long pfn;
+
+	if (!encl)
+		return VM_FAULT_SIGBUS;
+
+	mutex_lock(&encl->lock);
+
+	entry = sgx_encl_load_page(encl, addr);
+	if (IS_ERR(entry)) {
+		if (unlikely(PTR_ERR(entry) != -EBUSY))
+			ret = VM_FAULT_SIGBUS;
+
+		goto out;
+	}
+
+	if (!follow_pfn(vma, addr, &pfn))
+		goto out;
+
+	ret = vmf_insert_pfn(vma, addr, PFN_DOWN(entry->epc_page->desc));
+	if (ret != VM_FAULT_NOPAGE) {
+		ret = VM_FAULT_SIGBUS;
+		goto out;
+	}
+
+out:
+	mutex_unlock(&encl->lock);
+	return ret;
+}
+
+/**
+ * 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_prot_bits)
+{
+	unsigned long idx, idx_start, idx_end;
+	struct sgx_encl_page *page;
+
+	/*
+	 * Disallow RIE tasks as their VMA permissions might conflict with the
+	 * enclave page permissions.
+	 */
+	if (!!(current->personality & READ_IMPLIES_EXEC))
+		return -EACCES;
+
+	idx_start = PFN_DOWN(start);
+	idx_end = PFN_DOWN(end - 1);
+
+	for (idx = idx_start; idx <= idx_end; ++idx) {
+		mutex_lock(&encl->lock);
+		page = radix_tree_lookup(&encl->page_tree, idx);
+		mutex_unlock(&encl->lock);
+
+		if (!page || (~page->vm_max_prot_bits & vm_prot_bits))
+			return -EACCES;
+	}
+
+	return 0;
+}
+
+static int sgx_vma_mprotect(struct vm_area_struct *vma, unsigned long start,
+			    unsigned long end, unsigned long prot)
+{
+	return sgx_encl_may_map(vma->vm_private_data, start, end,
+				calc_vm_prot_bits(prot, 0));
+}
+
+const struct vm_operations_struct sgx_vm_ops = {
+	.open = sgx_vma_open,
+	.fault = sgx_vma_fault,
+	.may_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 &sgx_encl instance
+ */
+void sgx_encl_destroy(struct sgx_encl *encl)
+{
+	struct sgx_encl_page *entry;
+	struct radix_tree_iter iter;
+	void **slot;
+
+	atomic_or(SGX_ENCL_DEAD, &encl->flags);
+
+	radix_tree_for_each_slot(slot, &encl->page_tree, &iter, 0) {
+		entry = *slot;
+
+		if (entry->epc_page) {
+			sgx_free_epc_page(entry->epc_page);
+			encl->secs_child_cnt--;
+			entry->epc_page = NULL;
+		}
+
+		radix_tree_delete(&entry->encl->page_tree,
+				  PFN_DOWN(entry->desc));
+		kfree(entry);
+	}
+
+	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..1d1bc5d590ee
--- /dev/null
+++ b/arch/x86/kernel/cpu/sgx/encl.h
@@ -0,0 +1,87 @@
+/* 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/radix-tree.h>
+#include <linux/srcu.h>
+#include <linux/workqueue.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;
+	u64 secs_attributes;
+	u64 allowed_attributes;
+	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 radix_tree_root page_tree;
+	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_prot_bits);
+
+#endif /* _X86_ENCL_H */
diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
new file mode 100644
index 000000000000..420d13fc03da
--- /dev/null
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -0,0 +1,706 @@
+// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
+// Copyright(c) 2016-19 Intel Corporation.
+
+#include <asm/mman.h>
+#include <linux/mman.h>
+#include <linux/delay.h>
+#include <linux/file.h>
+#include <linux/hashtable.h>
+#include <linux/highmem.h>
+#include <linux/ratelimit.h>
+#include <linux/sched/signal.h>
+#include <linux/shmem_fs.h>
+#include <linux/slab.h>
+#include <linux/suspend.h>
+#include "driver.h"
+#include "encl.h"
+#include "encls.h"
+
+/* A per-cpu cache for the last known values of IA32_SGXLEPUBKEYHASHx MSRs. */
+static DEFINE_PER_CPU(u64 [4], sgx_lepubkeyhash_cache);
+
+static u32 sgx_calc_ssaframesize(u32 miscselect, u64 xfrm)
+{
+	u32 size_max = PAGE_SIZE;
+	u32 size;
+	int i;
+
+	for (i = 2; i < 64; i++) {
+		if (!((1 << i) & xfrm))
+			continue;
+
+		size = SGX_SSA_GPRS_SIZE + sgx_xsave_size_tbl[i];
+		if (miscselect & SGX_MISC_EXINFO)
+			size += SGX_SSA_MISC_EXINFO_SIZE;
+
+		if (size > size_max)
+			size_max = size;
+	}
+
+	return PFN_UP(size_max);
+}
+
+static int sgx_validate_secs(const struct sgx_secs *secs,
+			     unsigned long ssaframesize)
+{
+	if (secs->size < (2 * PAGE_SIZE) || !is_power_of_2(secs->size))
+		return -EINVAL;
+
+	if (secs->base & (secs->size - 1))
+		return -EINVAL;
+
+	if (secs->miscselect & sgx_misc_reserved_mask ||
+	    secs->attributes & sgx_attributes_reserved_mask ||
+	    secs->xfrm & sgx_xfrm_reserved_mask)
+		return -EINVAL;
+
+	if (secs->attributes & SGX_ATTR_MODE64BIT) {
+		if (secs->size > sgx_encl_size_max_64)
+			return -EINVAL;
+	} else if (secs->size > sgx_encl_size_max_32)
+		return -EINVAL;
+
+	if (!(secs->xfrm & XFEATURE_MASK_FP) ||
+	    !(secs->xfrm & XFEATURE_MASK_SSE) ||
+	    (((secs->xfrm >> XFEATURE_BNDREGS) & 1) !=
+	     ((secs->xfrm >> XFEATURE_BNDCSR) & 1)))
+		return -EINVAL;
+
+	if (!secs->ssa_frame_size || ssaframesize > secs->ssa_frame_size)
+		return -EINVAL;
+
+	if (memchr_inv(secs->reserved1, 0, sizeof(secs->reserved1)) ||
+	    memchr_inv(secs->reserved2, 0, sizeof(secs->reserved2)) ||
+	    memchr_inv(secs->reserved3, 0, sizeof(secs->reserved3)) ||
+	    memchr_inv(secs->reserved4, 0, sizeof(secs->reserved4)))
+		return -EINVAL;
+
+	return 0;
+}
+
+static struct sgx_encl_page *sgx_encl_page_alloc(struct sgx_encl *encl,
+						 unsigned long offset,
+						 u64 secinfo_flags)
+{
+	struct sgx_encl_page *encl_page;
+	unsigned long prot;
+
+	encl_page = kzalloc(sizeof(*encl_page), GFP_KERNEL);
+	if (!encl_page)
+		return ERR_PTR(-ENOMEM);
+
+	encl_page->desc = encl->base + offset;
+	encl_page->encl = encl;
+
+	prot = _calc_vm_trans(secinfo_flags, SGX_SECINFO_R, PROT_READ)  |
+	       _calc_vm_trans(secinfo_flags, SGX_SECINFO_W, PROT_WRITE) |
+	       _calc_vm_trans(secinfo_flags, SGX_SECINFO_X, PROT_EXEC);
+
+	/*
+	 * TCS pages must always RW set for CPU access while the SECINFO
+	 * permissions are *always* zero - the CPU ignores the user provided
+	 * values and silently overwrites them with zero permissions.
+	 */
+	if ((secinfo_flags & SGX_SECINFO_PAGE_TYPE_MASK) == SGX_SECINFO_TCS)
+		prot |= PROT_READ | PROT_WRITE;
+
+	/* Calculate maximum of the VM flags for the page. */
+	encl_page->vm_max_prot_bits = calc_vm_prot_bits(prot, 0);
+
+	return encl_page;
+}
+
+static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs)
+{
+	unsigned long encl_size = secs->size + PAGE_SIZE;
+	struct sgx_epc_page *secs_epc;
+	unsigned long ssaframesize;
+	struct sgx_pageinfo pginfo;
+	struct sgx_secinfo secinfo;
+	struct file *backing;
+	long ret;
+
+	if (atomic_read(&encl->flags) & SGX_ENCL_CREATED)
+		return -EINVAL;
+
+	ssaframesize = sgx_calc_ssaframesize(secs->miscselect, secs->xfrm);
+	if (sgx_validate_secs(secs, ssaframesize)) {
+		pr_debug("invalid SECS\n");
+		return -EINVAL;
+	}
+
+	backing = shmem_file_setup("SGX backing", encl_size + (encl_size >> 5),
+				   VM_NORESERVE);
+	if (IS_ERR(backing))
+		return PTR_ERR(backing);
+
+	encl->backing = backing;
+
+	secs_epc = __sgx_alloc_epc_page();
+	if (IS_ERR(secs_epc)) {
+		ret = PTR_ERR(secs_epc);
+		goto err_out_backing;
+	}
+
+	encl->secs.epc_page = secs_epc;
+
+	pginfo.addr = 0;
+	pginfo.contents = (unsigned long)secs;
+	pginfo.metadata = (unsigned long)&secinfo;
+	pginfo.secs = 0;
+	memset(&secinfo, 0, sizeof(secinfo));
+
+	ret = __ecreate((void *)&pginfo, sgx_get_epc_addr(secs_epc));
+	if (ret) {
+		pr_debug("ECREATE returned %ld\n", ret);
+		goto err_out;
+	}
+
+	if (secs->attributes & SGX_ATTR_DEBUG)
+		atomic_or(SGX_ENCL_DEBUG, &encl->flags);
+
+	encl->secs.encl = encl;
+	encl->secs_attributes = secs->attributes;
+	encl->allowed_attributes |= SGX_ATTR_ALLOWED_MASK;
+	encl->base = secs->base;
+	encl->size = secs->size;
+	encl->ssaframesize = secs->ssa_frame_size;
+
+	/*
+	 * Set SGX_ENCL_CREATED only after the enclave is fully prepped.  This
+	 * allows setting and checking enclave creation without having to take
+	 * encl->lock.
+	 */
+	atomic_or(SGX_ENCL_CREATED, &encl->flags);
+
+	return 0;
+
+err_out:
+	sgx_free_epc_page(encl->secs.epc_page);
+	encl->secs.epc_page = NULL;
+
+err_out_backing:
+	fput(encl->backing);
+	encl->backing = NULL;
+
+	return ret;
+}
+
+/**
+ * sgx_ioc_enclave_create - handler for %SGX_IOC_ENCLAVE_CREATE
+ * @filep:	open file to /dev/sgx
+ * @arg:	userspace pointer to a struct sgx_enclave_create instance
+ *
+ * Allocate kernel data structures for a new enclave and execute ECREATE after
+ * verifying the correctness of the provided SECS.
+ *
+ * Note, enforcement of restricted and disallowed attributes is deferred until
+ * sgx_ioc_enclave_init(), only the architectural correctness of the SECS is
+ * checked by sgx_ioc_enclave_create().
+ *
+ * Return:
+ *   0 on success,
+ *   -errno otherwise
+ */
+static long sgx_ioc_enclave_create(struct sgx_encl *encl, void __user *arg)
+{
+	struct sgx_enclave_create ecreate;
+	struct page *secs_page;
+	struct sgx_secs *secs;
+	int ret;
+
+	if (copy_from_user(&ecreate, arg, sizeof(ecreate)))
+		return -EFAULT;
+
+	secs_page = alloc_page(GFP_KERNEL);
+	if (!secs_page)
+		return -ENOMEM;
+
+	secs = kmap(secs_page);
+	if (copy_from_user(secs, (void __user *)ecreate.src, sizeof(*secs))) {
+		ret = -EFAULT;
+		goto out;
+	}
+
+	ret = sgx_encl_create(encl, secs);
+
+out:
+	kunmap(secs_page);
+	__free_page(secs_page);
+	return ret;
+}
+
+static int sgx_validate_secinfo(struct sgx_secinfo *secinfo)
+{
+	u64 perm = secinfo->flags & SGX_SECINFO_PERMISSION_MASK;
+	u64 pt = secinfo->flags & SGX_SECINFO_PAGE_TYPE_MASK;
+
+	if (pt != SGX_SECINFO_REG && pt != SGX_SECINFO_TCS)
+		return -EINVAL;
+
+	if ((perm & SGX_SECINFO_W) && !(perm & SGX_SECINFO_R))
+		return -EINVAL;
+
+	/*
+	 * CPU will silently overwrite the permissions as zero, which means
+	 * that we need to validate it ourselves.
+	 */
+	if (pt == SGX_SECINFO_TCS && perm)
+		return -EINVAL;
+
+	if (secinfo->flags & SGX_SECINFO_RESERVED_MASK)
+		return -EINVAL;
+
+	if (memchr_inv(secinfo->reserved, 0, sizeof(secinfo->reserved)))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int __sgx_encl_add_page(struct sgx_encl *encl,
+			       struct sgx_encl_page *encl_page,
+			       struct sgx_epc_page *epc_page,
+			       struct sgx_secinfo *secinfo, unsigned long src)
+{
+	struct sgx_pageinfo pginfo;
+	struct vm_area_struct *vma;
+	struct page *src_page;
+	int ret;
+
+	/* Query vma's VM_MAYEXEC as an indirect path_noexec() check. */
+	if (encl_page->vm_max_prot_bits & VM_EXEC) {
+		vma = find_vma(current->mm, src);
+		if (!vma)
+			return -EFAULT;
+
+		if (!(vma->vm_flags & VM_MAYEXEC))
+			return -EACCES;
+	}
+
+	ret = get_user_pages(src, 1, 0, &src_page, NULL);
+	if (ret < 1)
+		return ret;
+
+	pginfo.secs = (unsigned long)sgx_get_epc_addr(encl->secs.epc_page);
+	pginfo.addr = SGX_ENCL_PAGE_ADDR(encl_page);
+	pginfo.metadata = (unsigned long)secinfo;
+	pginfo.contents = (unsigned long)kmap_atomic(src_page);
+
+	ret = __eadd(&pginfo, sgx_get_epc_addr(epc_page));
+
+	kunmap_atomic((void *)pginfo.contents);
+	put_page(src_page);
+
+	return ret ? -EIO : 0;
+}
+
+static int __sgx_encl_extend(struct sgx_encl *encl,
+			     struct sgx_epc_page *epc_page)
+{
+	int ret;
+	int i;
+
+	for (i = 0; i < 16; i++) {
+		ret = __eextend(sgx_get_epc_addr(encl->secs.epc_page),
+				sgx_get_epc_addr(epc_page) + (i * 0x100));
+		if (ret) {
+			if (encls_failed(ret))
+				ENCLS_WARN(ret, "EEXTEND");
+			return -EIO;
+		}
+	}
+
+	return 0;
+}
+
+static int sgx_encl_add_page(struct sgx_encl *encl, unsigned long src,
+			     unsigned long offset, unsigned long length,
+			     struct sgx_secinfo *secinfo, unsigned long flags)
+{
+	struct sgx_encl_page *encl_page;
+	struct sgx_epc_page *epc_page;
+	int ret;
+
+	encl_page = sgx_encl_page_alloc(encl, offset, secinfo->flags);
+	if (IS_ERR(encl_page))
+		return PTR_ERR(encl_page);
+
+	epc_page = __sgx_alloc_epc_page();
+	if (IS_ERR(epc_page)) {
+		kfree(encl_page);
+		return PTR_ERR(epc_page);
+	}
+
+	if (atomic_read(&encl->flags) &
+	    (SGX_ENCL_INITIALIZED | SGX_ENCL_DEAD)) {
+		ret = -EFAULT;
+		goto err_out_free;
+	}
+
+	mmap_read_lock(current->mm);
+	mutex_lock(&encl->lock);
+
+	/*
+	 * Insert prior to EADD in case of OOM.  EADD modifies MRENCLAVE, i.e.
+	 * can't be gracefully unwound, while failure on EADD/EXTEND is limited
+	 * to userspace errors (or kernel/hardware bugs).
+	 */
+	ret = radix_tree_insert(&encl->page_tree, PFN_DOWN(encl_page->desc),
+				encl_page);
+	if (ret)
+		goto err_out_unlock;
+
+	ret = __sgx_encl_add_page(encl, encl_page, epc_page, secinfo,
+				  src);
+	if (ret)
+		goto err_out;
+
+	/*
+	 * Complete the "add" before doing the "extend" so that the "add"
+	 * isn't in a half-baked state in the extremely unlikely scenario the
+	 * the enclave will be destroyed in response to EEXTEND failure.
+	 */
+	encl_page->encl = encl;
+	encl_page->epc_page = epc_page;
+	encl->secs_child_cnt++;
+
+	if (flags & SGX_PAGE_MEASURE) {
+		ret = __sgx_encl_extend(encl, epc_page);
+		if (ret)
+			goto err_out;
+	}
+
+	mutex_unlock(&encl->lock);
+	mmap_read_unlock(current->mm);
+	return ret;
+
+err_out:
+	radix_tree_delete(&encl_page->encl->page_tree,
+			  PFN_DOWN(encl_page->desc));
+
+err_out_unlock:
+	mutex_unlock(&encl->lock);
+	mmap_read_unlock(current->mm);
+
+err_out_free:
+	sgx_free_epc_page(epc_page);
+	kfree(encl_page);
+
+	/*
+	 * Destroy enclave on ENCLS failure as this means that EPC has been
+	 * invalidated.
+	 */
+	if (ret == -EIO) {
+		mutex_lock(&encl->lock);
+		sgx_encl_destroy(encl);
+		mutex_unlock(&encl->lock);
+	}
+
+	return ret;
+}
+
+/**
+ * sgx_ioc_enclave_add_pages() - The handler for %SGX_IOC_ENCLAVE_ADD_PAGES
+ * @encl:       pointer to an enclave instance (via ioctl() file pointer)
+ * @arg:	a user pointer to a struct sgx_enclave_add_pages instance
+ *
+ * Add one or more pages to an uninitialized enclave, and optionally extend the
+ * measurement with the contents of the page. The address range of pages must
+ * be contiguous. The SECINFO and measurement mask are applied to all pages.
+ *
+ * A SECINFO for a TCS is required to always contain zero permissions because
+ * CPU silently zeros them. Allowing anything else would cause a mismatch in
+ * the measurement.
+ *
+ * mmap()'s protection bits are capped by the page permissions. For each page
+ * address, the maximum protection bits are computed with the following
+ * heuristics:
+ *
+ * 1. A regular page: PROT_R, PROT_W and PROT_X match the SECINFO permissions.
+ * 2. A TCS page: PROT_R | PROT_W.
+ *
+ * mmap() is not allowed to surpass the minimum of the maximum protection bits
+ * within the given address range.
+ *
+ * If ENCLS opcode fails, that effectively means that EPC has been invalidated.
+ * When this happens the enclave is destroyed and -EIO is returned to the
+ * caller.
+ *
+ * Return:
+ *   0 on success,
+ *   -EACCES if an executable source page is located in a noexec partition,
+ *   -EIO if either ENCLS[EADD] or ENCLS[EEXTEND] fails
+ *   -errno otherwise
+ */
+static long sgx_ioc_enclave_add_pages(struct sgx_encl *encl, void __user *arg)
+{
+	struct sgx_enclave_add_pages addp;
+	struct sgx_secinfo secinfo;
+	unsigned long c;
+	int ret;
+
+	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;
+
+	if (addp.offset + addp.length - PAGE_SIZE >= encl->size)
+		return -EINVAL;
+
+	if (copy_from_user(&secinfo, (void __user *)addp.secinfo,
+			   sizeof(secinfo)))
+		return -EFAULT;
+
+	if (sgx_validate_secinfo(&secinfo))
+		return -EINVAL;
+
+	for (c = 0 ; c < addp.length; c += PAGE_SIZE) {
+		if (signal_pending(current)) {
+			ret = -EINTR;
+			break;
+		}
+
+		if (need_resched())
+			cond_resched();
+
+		ret = sgx_encl_add_page(encl, addp.src + c, addp.offset + c,
+					addp.length - c, &secinfo, addp.flags);
+		if (ret)
+			break;
+	}
+
+	addp.count = c;
+
+	if (copy_to_user(arg, &addp, sizeof(addp)))
+		return -EFAULT;
+
+	return ret;
+}
+
+static int __sgx_get_key_hash(struct crypto_shash *tfm, const void *modulus,
+			      void *hash)
+{
+	SHASH_DESC_ON_STACK(shash, tfm);
+
+	shash->tfm = tfm;
+
+	return crypto_shash_digest(shash, modulus, SGX_MODULUS_SIZE, hash);
+}
+
+static int sgx_get_key_hash(const void *modulus, void *hash)
+{
+	struct crypto_shash *tfm;
+	int ret;
+
+	tfm = crypto_alloc_shash("sha256", 0, CRYPTO_ALG_ASYNC);
+	if (IS_ERR(tfm))
+		return PTR_ERR(tfm);
+
+	ret = __sgx_get_key_hash(tfm, modulus, hash);
+
+	crypto_free_shash(tfm);
+	return ret;
+}
+
+static void sgx_update_lepubkeyhash_msrs(u64 *lepubkeyhash, bool enforce)
+{
+	u64 *cache;
+	int i;
+
+	cache = per_cpu(sgx_lepubkeyhash_cache, smp_processor_id());
+	for (i = 0; i < 4; i++) {
+		if (enforce || (lepubkeyhash[i] != cache[i])) {
+			wrmsrl(MSR_IA32_SGXLEPUBKEYHASH0 + i, lepubkeyhash[i]);
+			cache[i] = lepubkeyhash[i];
+		}
+	}
+}
+
+static int sgx_einit(struct sgx_sigstruct *sigstruct, void *token,
+		     struct sgx_epc_page *secs, u64 *lepubkeyhash)
+{
+	int ret;
+
+	preempt_disable();
+	sgx_update_lepubkeyhash_msrs(lepubkeyhash, false);
+	ret = __einit(sigstruct, token, sgx_get_epc_addr(secs));
+	if (ret == SGX_INVALID_EINITTOKEN) {
+		sgx_update_lepubkeyhash_msrs(lepubkeyhash, true);
+		ret = __einit(sigstruct, token, sgx_get_epc_addr(secs));
+	}
+	preempt_enable();
+	return ret;
+}
+
+static int sgx_encl_init(struct sgx_encl *encl, struct sgx_sigstruct *sigstruct,
+			 void *token)
+{
+	u64 mrsigner[4];
+	int ret;
+	int i;
+	int j;
+
+	/* Check that the required attributes have been authorized. */
+	if (encl->secs_attributes & ~encl->allowed_attributes)
+		return -EACCES;
+
+	ret = sgx_get_key_hash(sigstruct->modulus, mrsigner);
+	if (ret)
+		return ret;
+
+	mutex_lock(&encl->lock);
+
+	if (atomic_read(&encl->flags) & SGX_ENCL_INITIALIZED) {
+		ret = -EFAULT;
+		goto err_out;
+	}
+
+	for (i = 0; i < SGX_EINIT_SLEEP_COUNT; i++) {
+		for (j = 0; j < SGX_EINIT_SPIN_COUNT; j++) {
+			ret = sgx_einit(sigstruct, token, encl->secs.epc_page,
+					mrsigner);
+			if (ret == SGX_UNMASKED_EVENT)
+				continue;
+			else
+				break;
+		}
+
+		if (ret != SGX_UNMASKED_EVENT)
+			break;
+
+		msleep_interruptible(SGX_EINIT_SLEEP_TIME);
+
+		if (signal_pending(current)) {
+			ret = -ERESTARTSYS;
+			goto err_out;
+		}
+	}
+
+	if (ret & ENCLS_FAULT_FLAG) {
+		if (encls_failed(ret))
+			ENCLS_WARN(ret, "EINIT");
+
+		sgx_encl_destroy(encl);
+		ret = -EFAULT;
+	} else if (ret) {
+		pr_debug("EINIT returned %d\n", ret);
+		ret = -EPERM;
+	} else {
+		atomic_or(SGX_ENCL_INITIALIZED, &encl->flags);
+	}
+
+err_out:
+	mutex_unlock(&encl->lock);
+	return ret;
+}
+
+/**
+ * sgx_ioc_enclave_init - handler for %SGX_IOC_ENCLAVE_INIT
+ *
+ * @filep:	open file to /dev/sgx
+ * @arg:	userspace pointer to a struct sgx_enclave_init instance
+ *
+ * Flush any outstanding enqueued EADD operations and perform EINIT.  The
+ * Launch Enclave Public Key Hash MSRs are rewritten as necessary to match
+ * the enclave's MRSIGNER, which is caculated from the provided sigstruct.
+ *
+ * Return:
+ *   0 on success,
+ *   SGX error code on EINIT failure,
+ *   -errno otherwise
+ */
+static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg)
+{
+	struct sgx_sigstruct *sigstruct;
+	struct sgx_enclave_init einit;
+	struct page *initp_page;
+	void *token;
+	int ret;
+
+	if (!(atomic_read(&encl->flags) & SGX_ENCL_CREATED))
+		return -EINVAL;
+
+	if (copy_from_user(&einit, arg, sizeof(einit)))
+		return -EFAULT;
+
+	initp_page = alloc_page(GFP_KERNEL);
+	if (!initp_page)
+		return -ENOMEM;
+
+	sigstruct = kmap(initp_page);
+	token = (void *)((unsigned long)sigstruct + PAGE_SIZE / 2);
+	memset(token, 0, SGX_LAUNCH_TOKEN_SIZE);
+
+	if (copy_from_user(sigstruct, (void __user *)einit.sigstruct,
+			   sizeof(*sigstruct))) {
+		ret = -EFAULT;
+		goto out;
+	}
+
+	/*
+	 * A legacy field used with Intel signed enclaves. These used to mean
+	 * regular and architectural enclaves. The CPU only accepts these values
+	 * but they do not have any other meaning.
+	 *
+	 * Thus, reject any other values.
+	 */
+	if (sigstruct->header.vendor != 0x0000 &&
+	    sigstruct->header.vendor != 0x8086) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	ret = sgx_encl_init(encl, sigstruct, token);
+
+out:
+	kunmap(initp_page);
+	__free_page(initp_page);
+	return ret;
+}
+
+
+long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
+{
+	struct sgx_encl *encl = filep->private_data;
+	int ret, encl_flags;
+
+	encl_flags = atomic_fetch_or(SGX_ENCL_IOCTL, &encl->flags);
+	if (encl_flags & SGX_ENCL_IOCTL)
+		return -EBUSY;
+
+	if (encl_flags & SGX_ENCL_DEAD) {
+		ret = -EFAULT;
+		goto out;
+	}
+
+	switch (cmd) {
+	case SGX_IOC_ENCLAVE_CREATE:
+		ret = sgx_ioc_enclave_create(encl, (void __user *)arg);
+		break;
+	case SGX_IOC_ENCLAVE_ADD_PAGES:
+		ret = sgx_ioc_enclave_add_pages(encl, (void __user *)arg);
+		break;
+	case SGX_IOC_ENCLAVE_INIT:
+		ret = sgx_ioc_enclave_init(encl, (void __user *)arg);
+		break;
+	default:
+		ret = -ENOIOCTLCMD;
+		break;
+	}
+
+out:
+	atomic_andnot(SGX_ENCL_IOCTL, &encl->flags);
+
+	return ret;
+}
diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index b776d249289f..506cb0756147 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];
@@ -259,6 +261,8 @@ static bool __init sgx_page_cache_init(void)
 
 static void __init sgx_init(void)
 {
+	int ret;
+
 	if (!boot_cpu_has(X86_FEATURE_SGX))
 		return;
 
@@ -268,8 +272,15 @@ 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

[PATCH v33 12/21] x86/sgx: Allow a limited use of ATTRIBUTE.PROVISIONKEY for attestation

[Jarkko Sakkinen]

Provisioning Certification Enclave (PCE), the root of trust for other
enclaves, generates a signing key from a fused key called Provisioning
Certification Key. PCE can then use this key to certify an attestation key
of a QE, e.g. we get the chain of trust down to the hardware if the Intel
signed PCE is used.

To use the needed keys, ATTRIBUTE.PROVISIONKEY is required but should be
only allowed for those who actually need it so that only the trusted
parties can certify QE's.

Obviously the attestation service should know the public key of the used
PCE and that way detect illegit attestation, but whitelisting the legit
users still adds an additional layer of defence.

Add new device file called /dev/sgx/provision. The sole purpose of this
file is to provide file descriptors that act as privilege tokens to allow
to build enclaves with ATTRIBUTE.PROVISIONKEY set. A new ioctl called
SGX_IOC_ENCLAVE_SET_ATTRIBUTE is used to assign this token to an enclave.

Cc: linux-security-module@vger.kernel.org
Acked-by: Jethro Beekman <jethro@fortanix.com>
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
 arch/x86/include/uapi/asm/sgx.h  | 11 ++++++++
 arch/x86/kernel/cpu/sgx/driver.c | 14 ++++++++++
 arch/x86/kernel/cpu/sgx/driver.h |  2 ++
 arch/x86/kernel/cpu/sgx/ioctl.c  | 47 ++++++++++++++++++++++++++++++++
 4 files changed, 74 insertions(+)

diff --git a/arch/x86/include/uapi/asm/sgx.h b/arch/x86/include/uapi/asm/sgx.h
index 5edb08ab8fd0..57d0d30c79b3 100644
--- a/arch/x86/include/uapi/asm/sgx.h
+++ b/arch/x86/include/uapi/asm/sgx.h
@@ -25,6 +25,8 @@ enum sgx_page_flags {
 	_IOWR(SGX_MAGIC, 0x01, struct sgx_enclave_add_pages)
 #define SGX_IOC_ENCLAVE_INIT \
 	_IOW(SGX_MAGIC, 0x02, struct sgx_enclave_init)
+#define SGX_IOC_ENCLAVE_SET_ATTRIBUTE \
+	_IOW(SGX_MAGIC, 0x03, struct sgx_enclave_set_attribute)
 
 /**
  * struct sgx_enclave_create - parameter structure for the
@@ -63,4 +65,13 @@ struct sgx_enclave_init {
 	__u64 sigstruct;
 };
 
+/**
+ * struct sgx_enclave_set_attribute - parameter structure for the
+ *				      %SGX_IOC_ENCLAVE_SET_ATTRIBUTE ioctl
+ * @attribute_fd:	file handle of the attribute file in the securityfs
+ */
+struct sgx_enclave_set_attribute {
+	__u64 attribute_fd;
+};
+
 #endif /* _UAPI_ASM_X86_SGX_H */
diff --git a/arch/x86/kernel/cpu/sgx/driver.c b/arch/x86/kernel/cpu/sgx/driver.c
index b4aa7b9f8376..d90114cec1c3 100644
--- a/arch/x86/kernel/cpu/sgx/driver.c
+++ b/arch/x86/kernel/cpu/sgx/driver.c
@@ -150,6 +150,13 @@ static struct miscdevice sgx_dev_enclave = {
 	.fops = &sgx_encl_fops,
 };
 
+static struct miscdevice sgx_dev_provision = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "provision",
+	.nodename = "sgx/provision",
+	.fops = &sgx_provision_fops,
+};
+
 int __init sgx_drv_init(void)
 {
 	unsigned int eax, ebx, ecx, edx;
@@ -190,5 +197,12 @@ int __init sgx_drv_init(void)
 		return ret;
 	}
 
+	ret = misc_register(&sgx_dev_provision);
+	if (ret) {
+		pr_err("Creating /dev/sgx/provision failed with %d.\n", ret);
+		misc_deregister(&sgx_dev_enclave);
+		return ret;
+	}
+
 	return 0;
 }
diff --git a/arch/x86/kernel/cpu/sgx/driver.h b/arch/x86/kernel/cpu/sgx/driver.h
index e4063923115b..72747d01c046 100644
--- a/arch/x86/kernel/cpu/sgx/driver.h
+++ b/arch/x86/kernel/cpu/sgx/driver.h
@@ -23,6 +23,8 @@ extern u64 sgx_attributes_reserved_mask;
 extern u64 sgx_xfrm_reserved_mask;
 extern u32 sgx_xsave_size_tbl[64];
 
+extern const struct file_operations sgx_provision_fops;
+
 long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg);
 
 int sgx_drv_init(void);
diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index 420d13fc03da..721096f1d5ba 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -669,6 +669,50 @@ static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg)
 	return ret;
 }
 
+/**
+ * sgx_ioc_enclave_set_attribute - handler for %SGX_IOC_ENCLAVE_SET_ATTRIBUTE
+ * @filep:	open file to /dev/sgx
+ * @arg:	userspace pointer to a struct sgx_enclave_set_attribute instance
+ *
+ * Mark the enclave as being allowed to access a restricted attribute bit.
+ * The requested attribute is specified via the attribute_fd field in the
+ * provided struct sgx_enclave_set_attribute.  The attribute_fd must be a
+ * handle to an SGX attribute file, e.g. "/dev/sgx/provision".
+ *
+ * Failure to explicitly request access to a restricted attribute will cause
+ * sgx_ioc_enclave_init() to fail.  Currently, the only restricted attribute
+ * is access to the PROVISION_KEY.
+ *
+ * Note, access to the EINITTOKEN_KEY is disallowed entirely.
+ *
+ * Return: 0 on success, -errno otherwise
+ */
+static long sgx_ioc_enclave_set_attribute(struct sgx_encl *encl,
+					  void __user *arg)
+{
+	struct sgx_enclave_set_attribute params;
+	struct file *attribute_file;
+	int ret;
+
+	if (copy_from_user(&params, arg, sizeof(params)))
+		return -EFAULT;
+
+	attribute_file = fget(params.attribute_fd);
+	if (!attribute_file)
+		return -EINVAL;
+
+	if (attribute_file->f_op != &sgx_provision_fops) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	encl->allowed_attributes |= SGX_ATTR_PROVISIONKEY;
+	ret = 0;
+
+out:
+	fput(attribute_file);
+	return ret;
+}
 
 long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
 {
@@ -694,6 +738,9 @@ long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
 	case SGX_IOC_ENCLAVE_INIT:
 		ret = sgx_ioc_enclave_init(encl, (void __user *)arg);
 		break;
+	case SGX_IOC_ENCLAVE_SET_ATTRIBUTE:
+		ret = sgx_ioc_enclave_set_attribute(encl, (void __user *)arg);
+		break;
 	default:
 		ret = -ENOIOCTLCMD;
 		break;
-- 
2.25.1

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

[Borislav Petkov]

On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:
> Intel Software Guard eXtensions (SGX) is a set of CPU instructions that
> can be used by applications to set aside private regions of code and
> data. The code outside the SGX hosted software entity is disallowed to
> access the memory inside the enclave enforced by the CPU. We call these
> entities as enclaves.
> 
> This commit implements a driver that provides an ioctl API to construct
> and run enclaves. Enclaves are constructed from pages residing in
> reserved physical memory areas. The contents of these pages can only be
> accessed when they are mapped as part of an enclave, by a hardware
> thread running inside the enclave.
> 
> The starting state of an enclave consists of a fixed measured set of
> pages that are copied to the EPC during the construction process by
> using ENCLS leaf functions and Software Enclave Control Structure (SECS)
> that defines the enclave properties.
> 
> Enclave are constructed by using ENCLS leaf functions ECREATE, EADD and
> EINIT. ECREATE initializes SECS, EADD copies pages from system memory to
> the EPC and EINIT check a given signed measurement and moves the enclave
> into a state ready for execution.
> 
> An initialized enclave can only be accessed through special Thread Control
> Structure (TCS) pages by using ENCLU (ring-3 only) leaf EENTER.  This leaf
> function converts a thread into enclave mode and continues the execution in
> the offset defined by the TCS provided to EENTER. An enclave is exited
> through syscall, exception, interrupts or by explicitly calling another
> ENCLU leaf EEXIT.
> 
> The permissions, which enclave page is added will set the limit for maximum
> permissions that can be set for mmap() and mprotect(). This will
> effectively allow to build different security schemes between producers and
> consumers of enclaves. Later on we can increase granularity with LSM hooks
> for page addition (i.e. for producers) and mapping of the enclave (i.e. for
> consumers)
> 
> Cc: linux-security-module@vger.kernel.org
> Acked-by: Jethro Beekman <jethro@fortanix.com>
> Tested-by: Jethro Beekman <jethro@fortanix.com>
> Tested-by: Haitao Huang <haitao.huang@linux.intel.com>
> Tested-by: Chunyang Hui <sanqian.hcy@antfin.com>
> Tested-by: Jordan Hand <jorhand@linux.microsoft.com>
> Tested-by: Nathaniel McCallum <npmccallum@redhat.com>
> Tested-by: Seth Moore <sethmo@google.com>
> Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Co-developed-by: Suresh Siddha <suresh.b.siddha@intel.com>
> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> ---
>  .../userspace-api/ioctl/ioctl-number.rst      |   1 +
>  arch/x86/include/uapi/asm/sgx.h               |  66 ++
>  arch/x86/kernel/cpu/sgx/Makefile              |   3 +
>  arch/x86/kernel/cpu/sgx/driver.c              | 194 +++++
>  arch/x86/kernel/cpu/sgx/driver.h              |  30 +
>  arch/x86/kernel/cpu/sgx/encl.c                | 335 +++++++++
>  arch/x86/kernel/cpu/sgx/encl.h                |  87 +++
>  arch/x86/kernel/cpu/sgx/ioctl.c               | 706 ++++++++++++++++++
>  arch/x86/kernel/cpu/sgx/main.c                |  11 +
>  9 files changed, 1433 insertions(+)
>  create mode 100644 arch/x86/include/uapi/asm/sgx.h
>  create mode 100644 arch/x86/kernel/cpu/sgx/driver.c
>  create mode 100644 arch/x86/kernel/cpu/sgx/driver.h
>  create mode 100644 arch/x86/kernel/cpu/sgx/encl.c
>  create mode 100644 arch/x86/kernel/cpu/sgx/encl.h
>  create mode 100644 arch/x86/kernel/cpu/sgx/ioctl.c
> 
> diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
> index 59472cd6a11d..35f713e3a267 100644
> --- a/Documentation/userspace-api/ioctl/ioctl-number.rst
> +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
> @@ -323,6 +323,7 @@ Code  Seq#    Include File                                           Comments
>                                                                       <mailto:tlewis@mindspring.com>
>  0xA3  90-9F  linux/dtlk.h
>  0xA4  00-1F  uapi/linux/tee.h                                        Generic TEE subsystem
> +0xA4  00-1F  uapi/asm/sgx.h                                          Intel SGX subsystem (a legit conflict as TEE and SGX do not co-exist)
>  0xAA  00-3F  linux/uapi/linux/userfaultfd.h
>  0xAB  00-1F  linux/nbd.h
>  0xAC  00-1F  linux/raw.h
> diff --git a/arch/x86/include/uapi/asm/sgx.h b/arch/x86/include/uapi/asm/sgx.h
> new file mode 100644
> index 000000000000..5edb08ab8fd0
> --- /dev/null
> +++ b/arch/x86/include/uapi/asm/sgx.h
> @@ -0,0 +1,66 @@
> +/* SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) WITH Linux-syscall-note */

Checkpatch complains here:

WARNING: 'SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) WITH Linux-syscall-note */' is not supported in LICENSES/...
#114: FILE: arch/x86/include/uapi/asm/sgx.h:1:
+/* SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) WITH Linux-syscall-note */

Also, you had all patches until now split nice and logically doing one
thing only.

But this one is huge. Why?

Why can't you split out the facilities which the driver uses: encl.[ch]
into a patch, then ioctl.c into a separate one and then the driver into
a third one? Or do they all belong together inseparably?

I guess I'll find out eventually but it would've been nice if they were
split out...

-- 
Regards/Gruss,
    Boris.

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

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

[Sean Christopherson]

On Thu, Jun 25, 2020 at 07:23:19PM +0200, Borislav Petkov wrote:
> Also, you had all patches until now split nice and logically doing one
> thing only.
> 
> But this one is huge. Why?
> 
> Why can't you split out the facilities which the driver uses: encl.[ch]
> into a patch, then ioctl.c into a separate one and then the driver into
> a third one? Or do they all belong together inseparably?
> 
> I guess I'll find out eventually but it would've been nice if they were
> split out...

Hmm, I think the most reasonable way to break up this beast would be to
incrementally introduce functionality.  E.g. four or so patches, one for
each ioctl() of ENCLAVE_CREATE, ENCLAVE_ADD_PAGES, ENCLAVE_INIT and
ENCLAVE_SET_ATTRIBUTE, in that order.

Splitting up by file probably wouldn't work very well.  The split is
pretty arbitrary, e.g. encl.[ch] isn't simply a pure representation of an
enclave, there is a lot of the driver details/dependencies in there, i.e.
the functionality between encl/ioctl/driver is all pretty intertwined.

But I think serially introducing each ioctl() would be fairly clean, and
would help readers/reviewers better understand SGX as the patches would
naturally document the process of building an enclave, e.g. CREATE the
enclave, then ADD_PAGES, then INIT the enclave.  SET_ATTRIBUTE is a bit
of an outlier in that it would be chronologically out of order with
respect to building the enclave, but I think that's ok. 

Jarkko, thoughts?

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

[Borislav Petkov]

On Thu, Jun 25, 2020 at 11:34:48AM -0700, Sean Christopherson wrote:
> Hmm, I think the most reasonable way to break up this beast would be to
> incrementally introduce functionality.  E.g. four or so patches, one for
> each ioctl() of ENCLAVE_CREATE, ENCLAVE_ADD_PAGES, ENCLAVE_INIT and
> ENCLAVE_SET_ATTRIBUTE, in that order.

Yeah, I guess I can try reviewing it this way too and address each ioctl
separately. You can try splitting later so that we don't waste time now.
It would be good to have it split eventually, though, so that it is more
palatable for other rewiewers too...

> Splitting up by file probably wouldn't work very well.  The split is
> pretty arbitrary, e.g. encl.[ch] isn't simply a pure representation of an
> enclave, there is a lot of the driver details/dependencies in there, i.e.
> the functionality between encl/ioctl/driver is all pretty intertwined.

... provided the functionality is not too intertwined to make a split
actually worse than a single big patch.

Thx.

-- 
Regards/Gruss,
    Boris.

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

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

[Borislav Petkov]

On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:

> Subject: Re: [PATCH v33 11/21] x86/sgx: Linux Enclave Driver
					 ^
					 Add

> Intel Software Guard eXtensions (SGX) is a set of CPU instructions that
> can be used by applications to set aside private regions of code and
> data. The code outside the SGX hosted software entity is disallowed to
> access the memory inside the enclave enforced by the CPU. We call these
> entities as enclaves.

s/as //

> This commit implements a driver that provides an ioctl API to construct

s/This commit implements/Implement/

> and run enclaves. Enclaves are constructed from pages residing in
> reserved physical memory areas. The contents of these pages can only be
> accessed when they are mapped as part of an enclave, by a hardware
> thread running inside the enclave.
> 
> The starting state of an enclave consists of a fixed measured set of
> pages that are copied to the EPC during the construction process by
> using ENCLS leaf functions and Software Enclave Control Structure (SECS)
> that defines the enclave properties.
> 
> Enclave are constructed by using ENCLS leaf functions ECREATE, EADD and

Enclaves

> EINIT. ECREATE initializes SECS, EADD copies pages from system memory to
> the EPC and EINIT check a given signed measurement and moves the enclave

		   checks

> into a state ready for execution.
> 
> An initialized enclave can only be accessed through special Thread Control
> Structure (TCS) pages by using ENCLU (ring-3 only) leaf EENTER.  This leaf
> function converts a thread into enclave mode and continues the execution in
> the offset defined by the TCS provided to EENTER. An enclave is exited
> through syscall, exception, interrupts or by explicitly calling another
> ENCLU leaf EEXIT.
> 
> The permissions, which enclave page is added will set the limit for maximum
> permissions that can be set for mmap() and mprotect().

I can't parse that sentence.

> This will
> effectively allow to build different security schemes between producers and
> consumers of enclaves. Later on we can increase granularity with LSM hooks
> for page addition (i.e. for producers) and mapping of the enclave (i.e. for
> consumers)

Other than that, nice explanation. I like that in a commit message.

Thx.

-- 
Regards/Gruss,
    Boris.

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

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

[Jarkko Sakkinen]

On Thu, Jun 25, 2020 at 07:23:19PM +0200, Borislav Petkov wrote:
> On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:
> > Intel Software Guard eXtensions (SGX) is a set of CPU instructions that
> > can be used by applications to set aside private regions of code and
> > data. The code outside the SGX hosted software entity is disallowed to
> > access the memory inside the enclave enforced by the CPU. We call these
> > entities as enclaves.
> > 
> > This commit implements a driver that provides an ioctl API to construct
> > and run enclaves. Enclaves are constructed from pages residing in
> > reserved physical memory areas. The contents of these pages can only be
> > accessed when they are mapped as part of an enclave, by a hardware
> > thread running inside the enclave.
> > 
> > The starting state of an enclave consists of a fixed measured set of
> > pages that are copied to the EPC during the construction process by
> > using ENCLS leaf functions and Software Enclave Control Structure (SECS)
> > that defines the enclave properties.
> > 
> > Enclave are constructed by using ENCLS leaf functions ECREATE, EADD and
> > EINIT. ECREATE initializes SECS, EADD copies pages from system memory to
> > the EPC and EINIT check a given signed measurement and moves the enclave
> > into a state ready for execution.
> > 
> > An initialized enclave can only be accessed through special Thread Control
> > Structure (TCS) pages by using ENCLU (ring-3 only) leaf EENTER.  This leaf
> > function converts a thread into enclave mode and continues the execution in
> > the offset defined by the TCS provided to EENTER. An enclave is exited
> > through syscall, exception, interrupts or by explicitly calling another
> > ENCLU leaf EEXIT.
> > 
> > The permissions, which enclave page is added will set the limit for maximum
> > permissions that can be set for mmap() and mprotect(). This will
> > effectively allow to build different security schemes between producers and
> > consumers of enclaves. Later on we can increase granularity with LSM hooks
> > for page addition (i.e. for producers) and mapping of the enclave (i.e. for
> > consumers)
> > 
> > Cc: linux-security-module@vger.kernel.org
> > Acked-by: Jethro Beekman <jethro@fortanix.com>
> > Tested-by: Jethro Beekman <jethro@fortanix.com>
> > Tested-by: Haitao Huang <haitao.huang@linux.intel.com>
> > Tested-by: Chunyang Hui <sanqian.hcy@antfin.com>
> > Tested-by: Jordan Hand <jorhand@linux.microsoft.com>
> > Tested-by: Nathaniel McCallum <npmccallum@redhat.com>
> > Tested-by: Seth Moore <sethmo@google.com>
> > Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
> > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> > Co-developed-by: Suresh Siddha <suresh.b.siddha@intel.com>
> > Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
> > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > ---
> >  .../userspace-api/ioctl/ioctl-number.rst      |   1 +
> >  arch/x86/include/uapi/asm/sgx.h               |  66 ++
> >  arch/x86/kernel/cpu/sgx/Makefile              |   3 +
> >  arch/x86/kernel/cpu/sgx/driver.c              | 194 +++++
> >  arch/x86/kernel/cpu/sgx/driver.h              |  30 +
> >  arch/x86/kernel/cpu/sgx/encl.c                | 335 +++++++++
> >  arch/x86/kernel/cpu/sgx/encl.h                |  87 +++
> >  arch/x86/kernel/cpu/sgx/ioctl.c               | 706 ++++++++++++++++++
> >  arch/x86/kernel/cpu/sgx/main.c                |  11 +
> >  9 files changed, 1433 insertions(+)
> >  create mode 100644 arch/x86/include/uapi/asm/sgx.h
> >  create mode 100644 arch/x86/kernel/cpu/sgx/driver.c
> >  create mode 100644 arch/x86/kernel/cpu/sgx/driver.h
> >  create mode 100644 arch/x86/kernel/cpu/sgx/encl.c
> >  create mode 100644 arch/x86/kernel/cpu/sgx/encl.h
> >  create mode 100644 arch/x86/kernel/cpu/sgx/ioctl.c
> > 
> > diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
> > index 59472cd6a11d..35f713e3a267 100644
> > --- a/Documentation/userspace-api/ioctl/ioctl-number.rst
> > +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
> > @@ -323,6 +323,7 @@ Code  Seq#    Include File                                           Comments
> >                                                                       <mailto:tlewis@mindspring.com>
> >  0xA3  90-9F  linux/dtlk.h
> >  0xA4  00-1F  uapi/linux/tee.h                                        Generic TEE subsystem
> > +0xA4  00-1F  uapi/asm/sgx.h                                          Intel SGX subsystem (a legit conflict as TEE and SGX do not co-exist)
> >  0xAA  00-3F  linux/uapi/linux/userfaultfd.h
> >  0xAB  00-1F  linux/nbd.h
> >  0xAC  00-1F  linux/raw.h
> > diff --git a/arch/x86/include/uapi/asm/sgx.h b/arch/x86/include/uapi/asm/sgx.h
> > new file mode 100644
> > index 000000000000..5edb08ab8fd0
> > --- /dev/null
> > +++ b/arch/x86/include/uapi/asm/sgx.h
> > @@ -0,0 +1,66 @@
> > +/* SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) WITH Linux-syscall-note */
> 
> Checkpatch complains here:
> 
> WARNING: 'SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) WITH Linux-syscall-note */' is not supported in LICENSES/...
> #114: FILE: arch/x86/include/uapi/asm/sgx.h:1:
> +/* SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) WITH Linux-syscall-note */
> 
> Also, you had all patches until now split nice and logically doing one
> thing only.
> 
> But this one is huge. Why?
> 
> Why can't you split out the facilities which the driver uses: encl.[ch]
> into a patch, then ioctl.c into a separate one and then the driver into
> a third one? Or do they all belong together inseparably?
> 
> I guess I'll find out eventually but it would've been nice if they were
> split out...

It's still kind a strongly connected set of functionalities, but I get
your point.

I'd consider splitting for a slighly different angle:

1. Commit for the base driver.
2. Commit for each ioctl, adding the necessary "framework" to get that
   piece of functionality completed. The order would be:
   A. Create
   B. Add
   C. Initialize

Would be probably easier to review also this way because the commit kind
of rationalizes why things exist.

What do you think?

/Jarkko
 
 /Jarkko

/Jarkko

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

[Borislav Petkov]

On Thu, Jun 25, 2020 at 11:21:48PM +0300, Jarkko Sakkinen wrote:
> Would be probably easier to review also this way because the commit kind
> of rationalizes why things exist.
> 
> What do you think?

Sounds like a plan but you can do this for the next version - no need to
do it now. I'll try to review this way, per ioctl as I said in my mail
to Sean.

Thx.

-- 
Regards/Gruss,
    Boris.

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

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

[Borislav Petkov]

On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:
> diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
> index 59472cd6a11d..35f713e3a267 100644
> --- a/Documentation/userspace-api/ioctl/ioctl-number.rst
> +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
> @@ -323,6 +323,7 @@ Code  Seq#    Include File                                           Comments
>                                                                       <mailto:tlewis@mindspring.com>
>  0xA3  90-9F  linux/dtlk.h
>  0xA4  00-1F  uapi/linux/tee.h                                        Generic TEE subsystem
> +0xA4  00-1F  uapi/asm/sgx.h                                          Intel SGX subsystem (a legit conflict as TEE and SGX do not co-exist)

Maybe add <mailto:linux-sgx@vger.kernel.org> ?

>  0xAA  00-3F  linux/uapi/linux/userfaultfd.h
>  0xAB  00-1F  linux/nbd.h
>  0xAC  00-1F  linux/raw.h

...

> +static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs)
> +{
> +	unsigned long encl_size = secs->size + PAGE_SIZE;

Wait, you just copied @secs from user memory in sgx_ioc_enclave_create()
and now use ->size unverified? You're kidding, right?

> +	struct sgx_epc_page *secs_epc;
> +	unsigned long ssaframesize;
> +	struct sgx_pageinfo pginfo;
> +	struct sgx_secinfo secinfo;
> +	struct file *backing;
> +	long ret;
> +
> +	if (atomic_read(&encl->flags) & SGX_ENCL_CREATED)
> +		return -EINVAL;
> +
> +	ssaframesize = sgx_calc_ssaframesize(secs->miscselect, secs->xfrm);

So this is using more un-validated user input to do further calculations.
What can possibly go wrong?

I sure hope *I* am wrong and am missing something here.

If not, please, for the next version, audit all your user input and
validate it before using it. Srsly.

> +	if (sgx_validate_secs(secs, ssaframesize)) {
> +		pr_debug("invalid SECS\n");
> +		return -EINVAL;
> +	}
> +
> +	backing = shmem_file_setup("SGX backing", encl_size + (encl_size >> 5),
> +				   VM_NORESERVE);
> +	if (IS_ERR(backing))
> +		return PTR_ERR(backing);
> +
> +	encl->backing = backing;
> +
> +	secs_epc = __sgx_alloc_epc_page();
> +	if (IS_ERR(secs_epc)) {
> +		ret = PTR_ERR(secs_epc);
> +		goto err_out_backing;
> +	}
> +
> +	encl->secs.epc_page = secs_epc;
> +
> +	pginfo.addr = 0;
> +	pginfo.contents = (unsigned long)secs;
> +	pginfo.metadata = (unsigned long)&secinfo;
> +	pginfo.secs = 0;
> +	memset(&secinfo, 0, sizeof(secinfo));
> +
> +	ret = __ecreate((void *)&pginfo, sgx_get_epc_addr(secs_epc));
> +	if (ret) {
> +		pr_debug("ECREATE returned %ld\n", ret);
> +		goto err_out;
> +	}
> +
> +	if (secs->attributes & SGX_ATTR_DEBUG)
> +		atomic_or(SGX_ENCL_DEBUG, &encl->flags);
> +
> +	encl->secs.encl = encl;
> +	encl->secs_attributes = secs->attributes;
> +	encl->allowed_attributes |= SGX_ATTR_ALLOWED_MASK;
> +	encl->base = secs->base;
> +	encl->size = secs->size;
> +	encl->ssaframesize = secs->ssa_frame_size;
> +
> +	/*
> +	 * Set SGX_ENCL_CREATED only after the enclave is fully prepped.  This
> +	 * allows setting and checking enclave creation without having to take
> +	 * encl->lock.
> +	 */
> +	atomic_or(SGX_ENCL_CREATED, &encl->flags);
> +
> +	return 0;
> +
> +err_out:
> +	sgx_free_epc_page(encl->secs.epc_page);
> +	encl->secs.epc_page = NULL;
> +
> +err_out_backing:
> +	fput(encl->backing);
> +	encl->backing = NULL;
> +
> +	return ret;
> +}
> +
> +/**
> + * sgx_ioc_enclave_create - handler for %SGX_IOC_ENCLAVE_CREATE
> + * @filep:	open file to /dev/sgx

That's

@encl: enclave pointer

or so.

> + * @arg:	userspace pointer to a struct sgx_enclave_create instance
> + *
> + * Allocate kernel data structures for a new enclave and execute ECREATE after
> + * verifying the correctness of the provided SECS.
> + *
> + * Note, enforcement of restricted and disallowed attributes is deferred until
> + * sgx_ioc_enclave_init(), only the architectural correctness of the SECS is
> + * checked by sgx_ioc_enclave_create().

Well, I don't see that checking. Where is it?

> + *
> + * Return:
> + *   0 on success,
> + *   -errno otherwise
> + */
> +static long sgx_ioc_enclave_create(struct sgx_encl *encl, void __user *arg)
> +{
> +	struct sgx_enclave_create ecreate;
> +	struct page *secs_page;
> +	struct sgx_secs *secs;
> +	int ret;
> +
> +	if (copy_from_user(&ecreate, arg, sizeof(ecreate)))
> +		return -EFAULT;
> +
> +	secs_page = alloc_page(GFP_KERNEL);
> +	if (!secs_page)
> +		return -ENOMEM;
> +
> +	secs = kmap(secs_page);
> +	if (copy_from_user(secs, (void __user *)ecreate.src, sizeof(*secs))) {
> +		ret = -EFAULT;
> +		goto out;
> +	}
> +
> +	ret = sgx_encl_create(encl, secs);
> +
> +out:
> +	kunmap(secs_page);
> +	__free_page(secs_page);
> +	return ret;
> +}

-- 
Regards/Gruss,
    Boris.

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

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

[Jarkko Sakkinen]

On Thu, Jun 25, 2020 at 10:25:39PM +0200, Borislav Petkov wrote:
> On Thu, Jun 25, 2020 at 11:21:48PM +0300, Jarkko Sakkinen wrote:
> > Would be probably easier to review also this way because the commit kind
> > of rationalizes why things exist.
> > 
> > What do you think?
> 
> Sounds like a plan but you can do this for the next version - no need to
> do it now. I'll try to review this way, per ioctl as I said in my mail
> to Sean.

OK, sure I won't rush with a new version :-)

The code has been reworked so many times that it is somewhat easy to
make such split and I think it is one measure that an implementation is
somewhat sound when parts of functionality build up cleanly on top of
each other.

/Jarkko

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

[Sean Christopherson]

On Fri, Jun 26, 2020 at 11:14:19AM +0200, Borislav Petkov wrote:
> On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:
> > +static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs)
> > +{
> > +	unsigned long encl_size = secs->size + PAGE_SIZE;
> 
> Wait, you just copied @secs from user memory in sgx_ioc_enclave_create()
> and now use ->size unverified? You're kidding, right?

The size of the enclave is checked in sgx_validate_secs() before it is used
to configure the shmem backing.
 
> > +	struct sgx_epc_page *secs_epc;
> > +	unsigned long ssaframesize;
> > +	struct sgx_pageinfo pginfo;
> > +	struct sgx_secinfo secinfo;
> > +	struct file *backing;
> > +	long ret;
> > +
> > +	if (atomic_read(&encl->flags) & SGX_ENCL_CREATED)
> > +		return -EINVAL;
> > +
> > +	ssaframesize = sgx_calc_ssaframesize(secs->miscselect, secs->xfrm);
> 
> So this is using more un-validated user input to do further calculations.
> What can possibly go wrong?

ssaframesize is also validated below, and the computations on miscselect and
xfm in sgx_calc_ssaframesize() are bounded such that bad input won't send
the kernel into the weeds.

That being said, I agree that it would be safer to move sgx_calc_ssaframesize()
inside sgx_validate_secs() and only compute encl_size after the secs is
validated.

> I sure hope *I* am wrong and am missing something here.
> 
> If not, please, for the next version, audit all your user input and
> validate it before using it. Srsly.
> 
> > +	if (sgx_validate_secs(secs, ssaframesize)) {
> > +		pr_debug("invalid SECS\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	backing = shmem_file_setup("SGX backing", encl_size + (encl_size >> 5),
> > +				   VM_NORESERVE);
> > +	if (IS_ERR(backing))
> > +		return PTR_ERR(backing);
> > +
> > +	encl->backing = backing;
> > +
> > +	secs_epc = __sgx_alloc_epc_page();
> > +	if (IS_ERR(secs_epc)) {
> > +		ret = PTR_ERR(secs_epc);
> > +		goto err_out_backing;
> > +	}
> > +
> > +	encl->secs.epc_page = secs_epc;
> > +
> > +	pginfo.addr = 0;
> > +	pginfo.contents = (unsigned long)secs;
> > +	pginfo.metadata = (unsigned long)&secinfo;
> > +	pginfo.secs = 0;
> > +	memset(&secinfo, 0, sizeof(secinfo));
> > +
> > +	ret = __ecreate((void *)&pginfo, sgx_get_epc_addr(secs_epc));
> > +	if (ret) {
> > +		pr_debug("ECREATE returned %ld\n", ret);
> > +		goto err_out;
> > +	}
> > +
> > +	if (secs->attributes & SGX_ATTR_DEBUG)
> > +		atomic_or(SGX_ENCL_DEBUG, &encl->flags);
> > +
> > +	encl->secs.encl = encl;
> > +	encl->secs_attributes = secs->attributes;
> > +	encl->allowed_attributes |= SGX_ATTR_ALLOWED_MASK;
> > +	encl->base = secs->base;
> > +	encl->size = secs->size;
> > +	encl->ssaframesize = secs->ssa_frame_size;
> > +
> > +	/*
> > +	 * Set SGX_ENCL_CREATED only after the enclave is fully prepped.  This
> > +	 * allows setting and checking enclave creation without having to take
> > +	 * encl->lock.
> > +	 */
> > +	atomic_or(SGX_ENCL_CREATED, &encl->flags);
> > +
> > +	return 0;
> > +
> > +err_out:
> > +	sgx_free_epc_page(encl->secs.epc_page);
> > +	encl->secs.epc_page = NULL;
> > +
> > +err_out_backing:
> > +	fput(encl->backing);
> > +	encl->backing = NULL;
> > +
> > +	return ret;
> > +}
> > +
> > +/**
> > + * sgx_ioc_enclave_create - handler for %SGX_IOC_ENCLAVE_CREATE
> > + * @filep:	open file to /dev/sgx
> 
> That's
> 
> @encl: enclave pointer
> 
> or so.
> 
> > + * @arg:	userspace pointer to a struct sgx_enclave_create instance
> > + *
> > + * Allocate kernel data structures for a new enclave and execute ECREATE after
> > + * verifying the correctness of the provided SECS.
> > + *
> > + * Note, enforcement of restricted and disallowed attributes is deferred until
> > + * sgx_ioc_enclave_init(), only the architectural correctness of the SECS is
> > + * checked by sgx_ioc_enclave_create().
> 
> Well, I don't see that checking. Where is it?
> 
> > + *
> > + * Return:
> > + *   0 on success,
> > + *   -errno otherwise
> > + */
> > +static long sgx_ioc_enclave_create(struct sgx_encl *encl, void __user *arg)
> > +{
> > +	struct sgx_enclave_create ecreate;
> > +	struct page *secs_page;
> > +	struct sgx_secs *secs;
> > +	int ret;
> > +
> > +	if (copy_from_user(&ecreate, arg, sizeof(ecreate)))
> > +		return -EFAULT;
> > +
> > +	secs_page = alloc_page(GFP_KERNEL);
> > +	if (!secs_page)
> > +		return -ENOMEM;
> > +
> > +	secs = kmap(secs_page);
> > +	if (copy_from_user(secs, (void __user *)ecreate.src, sizeof(*secs))) {
> > +		ret = -EFAULT;
> > +		goto out;
> > +	}
> > +
> > +	ret = sgx_encl_create(encl, secs);
> > +
> > +out:
> > +	kunmap(secs_page);
> > +	__free_page(secs_page);
> > +	return ret;
> > +}
> 
> -- 
> Regards/Gruss,
>     Boris.
> 
> https://people.kernel.org/tglx/notes-about-netiquette

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

[Jarkko Sakkinen]

On Thu, Jun 25, 2020 at 08:53:34PM +0200, Borislav Petkov wrote:
> On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:
> 
> > Subject: Re: [PATCH v33 11/21] x86/sgx: Linux Enclave Driver
> 					 ^
> 					 Add

I'll change it to "Add SGX enclave driver".

> 
> > Intel Software Guard eXtensions (SGX) is a set of CPU instructions that
> > can be used by applications to set aside private regions of code and
> > data. The code outside the SGX hosted software entity is disallowed to
> > access the memory inside the enclave enforced by the CPU. We call these
> > entities as enclaves.
> 
> s/as //
> 
> > This commit implements a driver that provides an ioctl API to construct
> 
> s/This commit implements/Implement/
> 
> > and run enclaves. Enclaves are constructed from pages residing in
> > reserved physical memory areas. The contents of these pages can only be
> > accessed when they are mapped as part of an enclave, by a hardware
> > thread running inside the enclave.
> > 
> > The starting state of an enclave consists of a fixed measured set of
> > pages that are copied to the EPC during the construction process by
> > using ENCLS leaf functions and Software Enclave Control Structure (SECS)
> > that defines the enclave properties.
> > 
> > Enclave are constructed by using ENCLS leaf functions ECREATE, EADD and
> 
> Enclaves
> 
> > EINIT. ECREATE initializes SECS, EADD copies pages from system memory to
> > the EPC and EINIT check a given signed measurement and moves the enclave
> 
> 		   checks
> 
> > into a state ready for execution.
> > 
> > An initialized enclave can only be accessed through special Thread Control
> > Structure (TCS) pages by using ENCLU (ring-3 only) leaf EENTER.  This leaf
> > function converts a thread into enclave mode and continues the execution in
> > the offset defined by the TCS provided to EENTER. An enclave is exited
> > through syscall, exception, interrupts or by explicitly calling another
> > ENCLU leaf EEXIT.
> > 
> > The permissions, which enclave page is added will set the limit for maximum
> > permissions that can be set for mmap() and mprotect().
> 
> I can't parse that sentence.

Neither can I.

> > This will
> > effectively allow to build different security schemes between producers and
> > consumers of enclaves. Later on we can increase granularity with LSM hooks
> > for page addition (i.e. for producers) and mapping of the enclave (i.e. for
> > consumers)

I rephrased the whole paragraph:

"
The mmap() permissions are capped by the contained enclave page
permissions. The mapped areas must also be opaque, i.e. each page address
must contain a page. This logic is implemented in sgx_encl_may_map().
"

> Other than that, nice explanation. I like that in a commit message.
> 
> Thx.

Thank you.

> 
> -- 
> Regards/Gruss,
>     Boris.
> 
> https://people.kernel.org/tglx/notes-about-netiquette

/Jarkko

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

[Jarkko Sakkinen]

On Thu, Jun 25, 2020 at 11:34:48AM -0700, Sean Christopherson wrote:
> On Thu, Jun 25, 2020 at 07:23:19PM +0200, Borislav Petkov wrote:
> > Also, you had all patches until now split nice and logically doing one
> > thing only.
> > 
> > But this one is huge. Why?
> > 
> > Why can't you split out the facilities which the driver uses: encl.[ch]
> > into a patch, then ioctl.c into a separate one and then the driver into
> > a third one? Or do they all belong together inseparably?
> > 
> > I guess I'll find out eventually but it would've been nice if they were
> > split out...
> 
> Hmm, I think the most reasonable way to break up this beast would be to
> incrementally introduce functionality.  E.g. four or so patches, one for
> each ioctl() of ENCLAVE_CREATE, ENCLAVE_ADD_PAGES, ENCLAVE_INIT and
> ENCLAVE_SET_ATTRIBUTE, in that order.
> 
> Splitting up by file probably wouldn't work very well.  The split is
> pretty arbitrary, e.g. encl.[ch] isn't simply a pure representation of an
> enclave, there is a lot of the driver details/dependencies in there, i.e.
> the functionality between encl/ioctl/driver is all pretty intertwined.
> 
> But I think serially introducing each ioctl() would be fairly clean, and
> would help readers/reviewers better understand SGX as the patches would
> naturally document the process of building an enclave, e.g. CREATE the
> enclave, then ADD_PAGES, then INIT the enclave.  SET_ATTRIBUTE is a bit
> of an outlier in that it would be chronologically out of order with
> respect to building the enclave, but I think that's ok. 
> 
> Jarkko, thoughts?

I proposed the same before I go this email so I guess we have a
consensus here.

/Jarkko

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

[Borislav Petkov]

On Fri, Jun 26, 2020 at 07:16:27AM -0700, Sean Christopherson wrote:
> That being said, I agree that it would be safer to move sgx_calc_ssaframesize()
> inside sgx_validate_secs() and only compute encl_size after the secs is
> validated.

Yap, that would be the right thing to do.

-- 
Regards/Gruss,
    Boris.

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

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

[Borislav Petkov]

On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:

...

This could use some commenting along the lines of:

"— If the enclave developer requires measurement of the page as a
proof for the content, use EEXTEND to add a measurement for 256 bytes of
the page. Repeat this operation until the entire page is measured."

At least this text from the SDM maps to the 256 bytes below. Otherwise
it is magic.

> +static int __sgx_encl_extend(struct sgx_encl *encl,
> +			     struct sgx_epc_page *epc_page)
> +{
> +	int ret;
> +	int i;
> +
> +	for (i = 0; i < 16; i++) {
> +		ret = __eextend(sgx_get_epc_addr(encl->secs.epc_page),
> +				sgx_get_epc_addr(epc_page) + (i * 0x100));
> +		if (ret) {
> +			if (encls_failed(ret))
> +				ENCLS_WARN(ret, "EEXTEND");
> +			return -EIO;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int sgx_encl_add_page(struct sgx_encl *encl, unsigned long src,
> +			     unsigned long offset, unsigned long length,
> +			     struct sgx_secinfo *secinfo, unsigned long flags)
> +{
> +	struct sgx_encl_page *encl_page;
> +	struct sgx_epc_page *epc_page;
> +	int ret;
> +
> +	encl_page = sgx_encl_page_alloc(encl, offset, secinfo->flags);
> +	if (IS_ERR(encl_page))
> +		return PTR_ERR(encl_page);
> +
> +	epc_page = __sgx_alloc_epc_page();
> +	if (IS_ERR(epc_page)) {
> +		kfree(encl_page);
> +		return PTR_ERR(epc_page);
> +	}
> +
> +	if (atomic_read(&encl->flags) &
> +	    (SGX_ENCL_INITIALIZED | SGX_ENCL_DEAD)) {
> +		ret = -EFAULT;
> +		goto err_out_free;
> +	}

You can do this first thing when you enter the function so that
you don't have to allocate needlessly in the error case, when
SGX_ENCL_INITIALIZED | SGX_ENCL_DEAD is set.

> +
> +	mmap_read_lock(current->mm);
> +	mutex_lock(&encl->lock);
> +
> +	/*
> +	 * Insert prior to EADD in case of OOM.  EADD modifies MRENCLAVE, i.e.
> +	 * can't be gracefully unwound, while failure on EADD/EXTEND is limited
> +	 * to userspace errors (or kernel/hardware bugs).
> +	 */
> +	ret = radix_tree_insert(&encl->page_tree, PFN_DOWN(encl_page->desc),
> +				encl_page);
> +	if (ret)
> +		goto err_out_unlock;
> +
> +	ret = __sgx_encl_add_page(encl, encl_page, epc_page, secinfo,
> +				  src);
> +	if (ret)
> +		goto err_out;
> +
> +	/*
> +	 * Complete the "add" before doing the "extend" so that the "add"
> +	 * isn't in a half-baked state in the extremely unlikely scenario the
> +	 * the enclave will be destroyed in response to EEXTEND failure.
> +	 */
> +	encl_page->encl = encl;
> +	encl_page->epc_page = epc_page;
> +	encl->secs_child_cnt++;
> +
> +	if (flags & SGX_PAGE_MEASURE) {
> +		ret = __sgx_encl_extend(encl, epc_page);
> +		if (ret)
> +			goto err_out;
> +	}
> +
> +	mutex_unlock(&encl->lock);
> +	mmap_read_unlock(current->mm);
> +	return ret;
> +
> +err_out:
> +	radix_tree_delete(&encl_page->encl->page_tree,
> +			  PFN_DOWN(encl_page->desc));
> +
> +err_out_unlock:
> +	mutex_unlock(&encl->lock);
> +	mmap_read_unlock(current->mm);
> +
> +err_out_free:
> +	sgx_free_epc_page(epc_page);
> +	kfree(encl_page);
> +
> +	/*
> +	 * Destroy enclave on ENCLS failure as this means that EPC has been
> +	 * invalidated.
> +	 */
> +	if (ret == -EIO) {
> +		mutex_lock(&encl->lock);
> +		sgx_encl_destroy(encl);
> +		mutex_unlock(&encl->lock);
> +	}
> +
> +	return ret;
> +}
> +
> +/**
> + * sgx_ioc_enclave_add_pages() - The handler for %SGX_IOC_ENCLAVE_ADD_PAGES
> + * @encl:       pointer to an enclave instance (via ioctl() file pointer)
> + * @arg:	a user pointer to a struct sgx_enclave_add_pages instance
> + *
> + * Add one or more pages to an uninitialized enclave, and optionally extend the

"uninitialized"?

Where is the test for SGX_ENCL_INITIALIZED and erroring out otherwise?

I.e., what happens if you add pages to an initialized enclave?

> + * measurement with the contents of the page. The address range of pages must
> + * be contiguous.

Must? Who is enforcing this? I'm trying to find where...

> The SECINFO and measurement mask are applied to all pages.
> + *
> + * A SECINFO for a TCS is required to always contain zero permissions because
> + * CPU silently zeros them. Allowing anything else would cause a mismatch in
> + * the measurement.
> + *
> + * mmap()'s protection bits are capped by the page permissions. For each page
> + * address, the maximum protection bits are computed with the following
> + * heuristics:
> + *
> + * 1. A regular page: PROT_R, PROT_W and PROT_X match the SECINFO permissions.
> + * 2. A TCS page: PROT_R | PROT_W.
> + *
> + * mmap() is not allowed to surpass the minimum of the maximum protection bits
> + * within the given address range.
> + *
> + * If ENCLS opcode fails, that effectively means that EPC has been invalidated.
> + * When this happens the enclave is destroyed and -EIO is returned to the
> + * caller.
> + *
> + * Return:
> + *   0 on success,
> + *   -EACCES if an executable source page is located in a noexec partition,
> + *   -EIO if either ENCLS[EADD] or ENCLS[EEXTEND] fails
> + *   -errno otherwise
> + */
> +static long sgx_ioc_enclave_add_pages(struct sgx_encl *encl, void __user *arg)
> +{
> +	struct sgx_enclave_add_pages addp;
> +	struct sgx_secinfo secinfo;
> +	unsigned long c;
> +	int ret;
> +
> +	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...

> +
> +	if (addp.offset + addp.length - PAGE_SIZE >= encl->size)
> +		return -EINVAL;
> +
> +	if (copy_from_user(&secinfo, (void __user *)addp.secinfo,
> +			   sizeof(secinfo)))
> +		return -EFAULT;
> +
> +	if (sgx_validate_secinfo(&secinfo))
> +		return -EINVAL;
> +
> +	for (c = 0 ; c < addp.length; c += PAGE_SIZE) {
> +		if (signal_pending(current)) {
> +			ret = -EINTR;
> +			break;
> +		}
> +
> +		if (need_resched())
> +			cond_resched();
> +
> +		ret = sgx_encl_add_page(encl, addp.src + c, addp.offset + c,
> +					addp.length - c, &secinfo, addp.flags);
> +		if (ret)
> +			break;
> +	}
> +
> +	addp.count = c;
> +
> +	if (copy_to_user(arg, &addp, sizeof(addp)))
> +		return -EFAULT;
> +
> +	return ret;
> +}
> +
-- 
Regards/Gruss,
    Boris.

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

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

[Borislav Petkov]

On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:
> +static int sgx_encl_init(struct sgx_encl *encl, struct sgx_sigstruct *sigstruct,
> +			 void *token)
> +{
> +	u64 mrsigner[4];
> +	int ret;
> +	int i;
> +	int j;
> +
> +	/* Check that the required attributes have been authorized. */
> +	if (encl->secs_attributes & ~encl->allowed_attributes)
> +		return -EACCES;
> +
> +	ret = sgx_get_key_hash(sigstruct->modulus, mrsigner);
> +	if (ret)
> +		return ret;
> +
> +	mutex_lock(&encl->lock);
> +
> +	if (atomic_read(&encl->flags) & SGX_ENCL_INITIALIZED) {
> +		ret = -EFAULT;
> +		goto err_out;
> +	}

That test should be the first thing this function or its caller does.

> +	for (i = 0; i < SGX_EINIT_SLEEP_COUNT; i++) {
> +		for (j = 0; j < SGX_EINIT_SPIN_COUNT; j++) {

Ew, what's that double-loop for?

It tries to init an enclave a bunch of times. Why does it need to init
more than once?

> +			ret = sgx_einit(sigstruct, token, encl->secs.epc_page,
> +					mrsigner);
> +			if (ret == SGX_UNMASKED_EVENT)
> +				continue;
> +			else
> +				break;
> +		}
> +
> +		if (ret != SGX_UNMASKED_EVENT)
> +			break;
> +
> +		msleep_interruptible(SGX_EINIT_SLEEP_TIME);
> +
> +		if (signal_pending(current)) {
> +			ret = -ERESTARTSYS;
> +			goto err_out;
> +		}
> +	}
> +
> +	if (ret & ENCLS_FAULT_FLAG) {
> +		if (encls_failed(ret))
> +			ENCLS_WARN(ret, "EINIT");
> +
> +		sgx_encl_destroy(encl);
> +		ret = -EFAULT;
> +	} else if (ret) {
> +		pr_debug("EINIT returned %d\n", ret);
> +		ret = -EPERM;
> +	} else {
> +		atomic_or(SGX_ENCL_INITIALIZED, &encl->flags);
> +	}
> +
> +err_out:
> +	mutex_unlock(&encl->lock);
> +	return ret;
> +}
> +
> +/**
> + * sgx_ioc_enclave_init - handler for %SGX_IOC_ENCLAVE_INIT
> + *
> + * @filep:	open file to /dev/sgx

@encl:       pointer to an enclave instance (via ioctl() file pointer)

> + * @arg:	userspace pointer to a struct sgx_enclave_init instance
> + *
> + * Flush any outstanding enqueued EADD operations and perform EINIT.  The
> + * Launch Enclave Public Key Hash MSRs are rewritten as necessary to match
> + * the enclave's MRSIGNER, which is caculated from the provided sigstruct.
> + *
> + * Return:
> + *   0 on success,
> + *   SGX error code on EINIT failure,
> + *   -errno otherwise
> + */
> +static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg)
> +{
> +	struct sgx_sigstruct *sigstruct;
> +	struct sgx_enclave_init einit;
> +	struct page *initp_page;
> +	void *token;
> +	int ret;
> +
> +	if (!(atomic_read(&encl->flags) & SGX_ENCL_CREATED))

Might just as well check the other flags: doing EINIT on an already
initialized enclave - SGX_ENCL_INITIALIZED - is perhaps a nono or
similarly on a SGX_ENCL_DEAD enclave.

And you could do similar sanity checks in the other ioctl functions.

-- 
Regards/Gruss,
    Boris.

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

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

[Sean Christopherson]

On Sat, Jun 27, 2020 at 07:43:35PM +0200, Borislav Petkov wrote:
> On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:
> > +static int sgx_encl_init(struct sgx_encl *encl, struct sgx_sigstruct *sigstruct,
> > +			 void *token)
> > +{
> > +	u64 mrsigner[4];
> > +	int ret;
> > +	int i;
> > +	int j;
> > +
> > +	/* Check that the required attributes have been authorized. */
> > +	if (encl->secs_attributes & ~encl->allowed_attributes)
> > +		return -EACCES;
> > +
> > +	ret = sgx_get_key_hash(sigstruct->modulus, mrsigner);
> > +	if (ret)
> > +		return ret;
> > +
> > +	mutex_lock(&encl->lock);
> > +
> > +	if (atomic_read(&encl->flags) & SGX_ENCL_INITIALIZED) {
> > +		ret = -EFAULT;
> > +		goto err_out;
> > +	}
> 
> That test should be the first thing this function or its caller does.

Hmm, I was going to say that SGX_ENCL_INITIALIZED can't be checked until
encl->lock is held, but that's not true for this path as mutual exclusion
is provided by the SGX_ENCL_IOCTL flag.  So yeah, this can be checked at
the same time as SGX_ENCL_CREATED in sgx_ioc_enclave_init().

> > +	for (i = 0; i < SGX_EINIT_SLEEP_COUNT; i++) {
> > +		for (j = 0; j < SGX_EINIT_SPIN_COUNT; j++) {
> 
> Ew, what's that double-loop for?
> 
> It tries to init an enclave a bunch of times. Why does it need to init
> more than once?

ENCLS[EINIT] is interruptible because it has such a high latency, e.g. 50k+
cycles on success.  If an IRQ/NMI/SMI becomes pending, EINIT may fail with
SGX_UNMASKED_EVENT so that the event can be serviced.

The idea behind the double loop is to try EINIT in a tight loop, then back
off and sleep for a while before retrying that tight inner loop.

> > +			ret = sgx_einit(sigstruct, token, encl->secs.epc_page,
> > +					mrsigner);
> > +			if (ret == SGX_UNMASKED_EVENT)
> > +				continue;
> > +			else
> > +				break;
> > +		}
> > +
> > +		if (ret != SGX_UNMASKED_EVENT)
> > +			break;
> > +
> > +		msleep_interruptible(SGX_EINIT_SLEEP_TIME);
> > +
> > +		if (signal_pending(current)) {
> > +			ret = -ERESTARTSYS;
> > +			goto err_out;
> > +		}
> > +	}
> > +
> > +	if (ret & ENCLS_FAULT_FLAG) {
> > +		if (encls_failed(ret))
> > +			ENCLS_WARN(ret, "EINIT");
> > +
> > +		sgx_encl_destroy(encl);
> > +		ret = -EFAULT;
> > +	} else if (ret) {
> > +		pr_debug("EINIT returned %d\n", ret);
> > +		ret = -EPERM;
> > +	} else {
> > +		atomic_or(SGX_ENCL_INITIALIZED, &encl->flags);
> > +	}
> > +
> > +err_out:
> > +	mutex_unlock(&encl->lock);
> > +	return ret;
> > +}
> > +
> > +/**
> > + * sgx_ioc_enclave_init - handler for %SGX_IOC_ENCLAVE_INIT
> > + *
> > + * @filep:	open file to /dev/sgx
> 
> @encl:       pointer to an enclave instance (via ioctl() file pointer)
> 
> > + * @arg:	userspace pointer to a struct sgx_enclave_init instance
> > + *
> > + * Flush any outstanding enqueued EADD operations and perform EINIT.  The
> > + * Launch Enclave Public Key Hash MSRs are rewritten as necessary to match
> > + * the enclave's MRSIGNER, which is caculated from the provided sigstruct.
> > + *
> > + * Return:
> > + *   0 on success,
> > + *   SGX error code on EINIT failure,
> > + *   -errno otherwise
> > + */
> > +static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg)
> > +{
> > +	struct sgx_sigstruct *sigstruct;
> > +	struct sgx_enclave_init einit;
> > +	struct page *initp_page;
> > +	void *token;
> > +	int ret;
> > +
> > +	if (!(atomic_read(&encl->flags) & SGX_ENCL_CREATED))
> 
> Might just as well check the other flags: doing EINIT on an already
> initialized enclave - SGX_ENCL_INITIALIZED - is perhaps a nono or
> similarly on a SGX_ENCL_DEAD enclave.
> 
> And you could do similar sanity checks in the other ioctl functions.

Ya, as above, SGX_ENCL_INITIALIZED can be checked here.

SGX_ENCL_DEAD is actually already checked in in the top level sgx_ioctl(),
i.e. the check in sgx_encl_add_page() can technically be flat out dropped.

I say "technically" because I'm a bit torn over SGX_ENCL_DEAD; encl->lock
must be held to SGX_ENCL_DEAD (the page fault and reclaim flows rely on
this), but as it stands today only ioctl() paths (guarded by SGX_ENCL_IOCTL)
and sgx_release() (makes the ioctls() unreachable) set SGX_ENCL_DEAD.

So it's safe to check SGX_ENCL_DEAD from ioctl() context without holding
encl->lock, at least in the current code base, but it feels weird/sketchy.

In the end I don't think I have a strong opinion.  Removing the technically
unnecessary DEAD check in sgx_encl_add_page() is the simplest change, so it
may make sense to do that and nothing more for initial upstreaming.  Long
term, I fully expect we'll add paths that set SGX_ENCL_DEAD outside of
ioctl() context, e.g. to handle EPC OOM, but it wouldn't be a bad thing to
have a standalone commit in a future series to add DEAD checks (under
encl->lock) in the ADD and INIT flows.

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

[Borislav Petkov]

On Mon, Jun 29, 2020 at 08:27:19AM -0700, Sean Christopherson wrote:
> Hmm, I was going to say that SGX_ENCL_INITIALIZED can't be checked until
> encl->lock is held, but that's not true for this path as mutual exclusion
> is provided by the SGX_ENCL_IOCTL flag.  So yeah, this can be checked at
> the same time as SGX_ENCL_CREATED in sgx_ioc_enclave_init().

Right, so my point is to have state checks for flags which make sense in
all ioctl entry points, in order to catch a misuse early. But we're on
the same page.

> ENCLS[EINIT] is interruptible because it has such a high latency, e.g. 50k+
> cycles on success.  If an IRQ/NMI/SMI becomes pending, EINIT may fail with
> SGX_UNMASKED_EVENT so that the event can be serviced.
>
> The idea behind the double loop is to try EINIT in a tight loop, then back
> off and sleep for a while before retrying that tight inner loop.

That gist of that kinda wants to be in a comment over that double-loop for
future on-lookers.

Thx.

-- 
Regards/Gruss,
    Boris.

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

Re: [PATCH v33 12/21] x86/sgx: Allow a limited use of ATTRIBUTE.PROVISIONKEY for attestation

[Borislav Petkov]

On Thu, Jun 18, 2020 at 01:08:34AM +0300, Jarkko Sakkinen wrote:
> Provisioning Certification Enclave (PCE), the root of trust for other
> enclaves, generates a signing key from a fused key called Provisioning
> Certification Key. PCE can then use this key to certify an attestation key
> of a QE, e.g. we get the chain of trust down to the hardware if the Intel

What's a QE?

I don't see this acronym resolved anywhere in the whole patchset.

> signed PCE is used.
> 
> To use the needed keys, ATTRIBUTE.PROVISIONKEY is required but should be
> only allowed for those who actually need it so that only the trusted
> parties can certify QE's.
> 
> Obviously the attestation service should know the public key of the used
> PCE and that way detect illegit attestation, but whitelisting the legit
> users still adds an additional layer of defence.
> 
> Add new device file called /dev/sgx/provision. The sole purpose of this
> file is to provide file descriptors that act as privilege tokens to allow
> to build enclaves with ATTRIBUTE.PROVISIONKEY set. A new ioctl called
> SGX_IOC_ENCLAVE_SET_ATTRIBUTE is used to assign this token to an enclave.

So I'm sure I'm missing something here: what controls which
enclave can open /dev/sgx/provision and thus pass the FD to
SGX_IOC_ENCLAVE_SET_ATTRIBUTE?

And in general, how does that whole flow look like: what calls
SGX_IOC_ENCLAVE_SET_ATTRIBUTE when?

Thx.

-- 
Regards/Gruss,
    Boris.

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

Re: [PATCH v33 12/21] x86/sgx: Allow a limited use of ATTRIBUTE.PROVISIONKEY for attestation

[Sean Christopherson]

On Mon, Jun 29, 2020 at 06:02:42PM +0200, Borislav Petkov wrote:
> On Thu, Jun 18, 2020 at 01:08:34AM +0300, Jarkko Sakkinen wrote:
> > Provisioning Certification Enclave (PCE), the root of trust for other
> > enclaves, generates a signing key from a fused key called Provisioning
> > Certification Key. PCE can then use this key to certify an attestation key
> > of a QE, e.g. we get the chain of trust down to the hardware if the Intel
> 
> What's a QE?
> 
> I don't see this acronym resolved anywhere in the whole patchset.

Quoting Enclave.

> > signed PCE is used.
> > 
> > To use the needed keys, ATTRIBUTE.PROVISIONKEY is required but should be
> > only allowed for those who actually need it so that only the trusted
> > parties can certify QE's.
> > 
> > Obviously the attestation service should know the public key of the used
> > PCE and that way detect illegit attestation, but whitelisting the legit
> > users still adds an additional layer of defence.
> > 
> > Add new device file called /dev/sgx/provision. The sole purpose of this
> > file is to provide file descriptors that act as privilege tokens to allow
> > to build enclaves with ATTRIBUTE.PROVISIONKEY set. A new ioctl called
> > SGX_IOC_ENCLAVE_SET_ATTRIBUTE is used to assign this token to an enclave.
> 
> So I'm sure I'm missing something here: what controls which
> enclave can open /dev/sgx/provision and thus pass the FD to
> SGX_IOC_ENCLAVE_SET_ATTRIBUTE?

/dev/sgx/provision is root-only by default, the expectation is that the admin
will configure the system to grant only specific enclaves access to the
PROVISION_KEY.

> And in general, how does that whole flow look like: what calls
> SGX_IOC_ENCLAVE_SET_ATTRIBUTE when?

The basic gist is that the host process of an enclave that needs/wants access
to the PROVISION_KEY will invoke SGX_IOC_ENCLAVE_SET_ATTRIBUTE when building
the enclave.  Any enclave can request access to PROVISION_KEY, but practically
speaking only the PCE and QE (or their non-Intel equivalents) actually need
access to the key.  KVM (future series) will also respect /dev/sgx/provision,
i.e. require a similar ioctl() to expose the PROVISION_KEY to a guest.

E.g. for my own personal testing, I never do anything attestation related, so
none of the enclaves I run request PROVISION_KEY, but I do expose it to VMs to
test the KVM paths.

In this series, access is fairly binary, i.e. there's no additional kernel
infrastructure to help userspace make per-enclave decisions.  There have been
more than a few proposals on how to extend the kernel to help provide better
granularity, e.g. LSM hooks, but it was generally agreed to punt that stuff
to post-upstreaming to keep things "simple" once we went far enough down
various paths to ensure we weren't painting ourselves into a corner.

If you want super gory details, Intel's whitepaper on attestation in cloud
environments is a good starting point[*], but I don't recommended doing much
more than skimming unless you really like attestation stuff or are
masochistic, which IMO amount to the same thing :-)

[*] https://download.01.org/intel-sgx/dcap-1.0/docs/SGX_ECDSA_QuoteGenReference_DCAP_API_Linux_1.0.pdf

Re: [PATCH v33 12/21] x86/sgx: Allow a limited use of ATTRIBUTE.PROVISIONKEY for attestation

[Borislav Petkov]

On Mon, Jun 29, 2020 at 03:04:00PM -0700, Sean Christopherson wrote:
> > I don't see this acronym resolved anywhere in the whole patchset.
> 
> Quoting Enclave.

Yah, pls add it somewhere.

> /dev/sgx/provision is root-only by default, the expectation is that the admin
> will configure the system to grant only specific enclaves access to the
> PROVISION_KEY.

Uuh, I don't like "the expectation is" - the reality happens to turn
differently, more often than not.

> In this series, access is fairly binary, i.e. there's no additional kernel
> infrastructure to help userspace make per-enclave decisions.  There have been
> more than a few proposals on how to extend the kernel to help provide better
> granularity, e.g. LSM hooks, but it was generally agreed to punt that stuff
> to post-upstreaming to keep things "simple" once we went far enough down
> various paths to ensure we weren't painting ourselves into a corner.

So this all sounds to me like we should not upstream /dev/sgx/provision
now but delay it until the infrastructure for that has been made more
concrete. We can always add it then. Changing it after the fact -
if we have to and for whatever reason - would be a lot harder for a
user-visible interface which someone has started using already.

So I'd leave  that out from the initial patchset.

> If you want super gory details, Intel's whitepaper on attestation in cloud
> environments is a good starting point[*], but I don't recommended doing much
> more than skimming unless you really like attestation stuff or are
> masochistic, which IMO amount to the same thing :-)

No thanks. :)

-- 
Regards/Gruss,
    Boris.

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

Re: [PATCH v33 12/21] x86/sgx: Allow a limited use of ATTRIBUTE.PROVISIONKEY for attestation

[Sean Christopherson]

On Tue, Jun 30, 2020 at 10:49:56AM +0200, Borislav Petkov wrote:
> On Mon, Jun 29, 2020 at 03:04:00PM -0700, Sean Christopherson wrote:
> > /dev/sgx/provision is root-only by default, the expectation is that the admin
> > will configure the system to grant only specific enclaves access to the
> > PROVISION_KEY.
> 
> Uuh, I don't like "the expectation is" - the reality happens to turn
> differently, more often than not.

Would it help if I worded it as "only root should ever be able to run an
enclave with access to PROVISION_KEY"?  We obviously can't control what
admins actually do, hence my wording of it as the expected behavior.

> > In this series, access is fairly binary, i.e. there's no additional kernel
> > infrastructure to help userspace make per-enclave decisions.  There have been
> > more than a few proposals on how to extend the kernel to help provide better
> > granularity, e.g. LSM hooks, but it was generally agreed to punt that stuff
> > to post-upstreaming to keep things "simple" once we went far enough down
> > various paths to ensure we weren't painting ourselves into a corner.
> 
> So this all sounds to me like we should not upstream /dev/sgx/provision
> now but delay it until the infrastructure for that has been made more
> concrete. We can always add it then. Changing it after the fact -
> if we have to and for whatever reason - would be a lot harder for a
> user-visible interface which someone has started using already.

The userspace and attestation infrastructure is very concrete, i.e. the
need for userspace to be able to access PROVISION_KEY is there, as is the
desire to be able to restrict access to PROVISION_KEY, e.g. I believe Andy
Lutomirski originally requested the ability to restrict access.

The additional infrastructure for per-enclave decisions is somewhat
orthogonal to the PROVISION_KEY, e.g. they won't necessarily be employed
by everyone running enclaves, and environments that do have per-enclave
policies would still likely want the extra layer of restriction for
PROVISION_KEY.  I only brought the additional policy crud to call out that
we've done enough path-finding on additional restrictions to have strong
confidence that adding /dev/sgx/provision won't prevent us from adding more
fine grained control in the future.

> So I'd leave  that out from the initial patchset.

Re: [PATCH v33 12/21] x86/sgx: Allow a limited use of ATTRIBUTE.PROVISIONKEY for attestation

[Andy Lutomirski]

On Tue, Jun 30, 2020 at 7:20 AM Sean Christopherson
<sean.j.christopherson@intel.com> wrote:
>
> On Tue, Jun 30, 2020 at 10:49:56AM +0200, Borislav Petkov wrote:
> > On Mon, Jun 29, 2020 at 03:04:00PM -0700, Sean Christopherson wrote:
> > > /dev/sgx/provision is root-only by default, the expectation is that the admin
> > > will configure the system to grant only specific enclaves access to the
> > > PROVISION_KEY.
> >
> > Uuh, I don't like "the expectation is" - the reality happens to turn
> > differently, more often than not.
>
> Would it help if I worded it as "only root should ever be able to run an
> enclave with access to PROVISION_KEY"?  We obviously can't control what
> admins actually do, hence my wording of it as the expected behavior.
>
> > > In this series, access is fairly binary, i.e. there's no additional kernel
> > > infrastructure to help userspace make per-enclave decisions.  There have been
> > > more than a few proposals on how to extend the kernel to help provide better
> > > granularity, e.g. LSM hooks, but it was generally agreed to punt that stuff
> > > to post-upstreaming to keep things "simple" once we went far enough down
> > > various paths to ensure we weren't painting ourselves into a corner.
> >
> > So this all sounds to me like we should not upstream /dev/sgx/provision
> > now but delay it until the infrastructure for that has been made more
> > concrete. We can always add it then. Changing it after the fact -
> > if we have to and for whatever reason - would be a lot harder for a
> > user-visible interface which someone has started using already.
>
> The userspace and attestation infrastructure is very concrete, i.e. the
> need for userspace to be able to access PROVISION_KEY is there, as is the
> desire to be able to restrict access to PROVISION_KEY, e.g. I believe Andy
> Lutomirski originally requested the ability to restrict access.
>
> The additional infrastructure for per-enclave decisions is somewhat
> orthogonal to the PROVISION_KEY, e.g. they won't necessarily be employed
> by everyone running enclaves, and environments that do have per-enclave
> policies would still likely want the extra layer of restriction for
> PROVISION_KEY.  I only brought the additional policy crud to call out that
> we've done enough path-finding on additional restrictions to have strong
> confidence that adding /dev/sgx/provision won't prevent us from adding more
> fine grained control in the future.

I agree.

I anticipate that most of the nasty fine-grained stuff will end up in
userspace down the road.  Systems can be configured such that
provisioning is done as root, or systems can end up with fancy SELinux
rules or daemons that pass around fds or whatever, but all of this can
be done with the kernel code in this patchset.

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

[Sean Christopherson]

On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:
> +static int sgx_validate_secs(const struct sgx_secs *secs,
> +			     unsigned long ssaframesize)
> +{
> +	if (secs->size < (2 * PAGE_SIZE) || !is_power_of_2(secs->size))
> +		return -EINVAL;
> +
> +	if (secs->base & (secs->size - 1))
> +		return -EINVAL;
> +
> +	if (secs->miscselect & sgx_misc_reserved_mask ||
> +	    secs->attributes & sgx_attributes_reserved_mask ||
> +	    secs->xfrm & sgx_xfrm_reserved_mask)
> +		return -EINVAL;
> +
> +	if (secs->attributes & SGX_ATTR_MODE64BIT) {
> +		if (secs->size > sgx_encl_size_max_64)
> +			return -EINVAL;
> +	} else if (secs->size > sgx_encl_size_max_32)
> +		return -EINVAL;

These should be >=, not >, the SDM uses one of those fancy ≥ ligatures.

Internal versions use more obvious pseudocode, e.g.:

    if ((DS:TMP_SECS.ATTRIBUTES.MODE64BIT = 1) AND
        (DS:TMP_SECS.SIZE AND (~((1 << CPUID.18.0:EDX[15:8]) – 1)))
    {
        #GP(0);
    }

> +
> +	if (!(secs->xfrm & XFEATURE_MASK_FP) ||
> +	    !(secs->xfrm & XFEATURE_MASK_SSE) ||
> +	    (((secs->xfrm >> XFEATURE_BNDREGS) & 1) !=
> +	     ((secs->xfrm >> XFEATURE_BNDCSR) & 1)))
> +		return -EINVAL;
> +
> +	if (!secs->ssa_frame_size || ssaframesize > secs->ssa_frame_size)
> +		return -EINVAL;
> +
> +	if (memchr_inv(secs->reserved1, 0, sizeof(secs->reserved1)) ||
> +	    memchr_inv(secs->reserved2, 0, sizeof(secs->reserved2)) ||
> +	    memchr_inv(secs->reserved3, 0, sizeof(secs->reserved3)) ||
> +	    memchr_inv(secs->reserved4, 0, sizeof(secs->reserved4)))
> +		return -EINVAL;
> +
> +	return 0;
> +}

Re: [PATCH v33 12/21] x86/sgx: Allow a limited use of ATTRIBUTE.PROVISIONKEY for attestation

[Dr. Greg]

Good afternoon, I hope the week is progressing productively to an end
for everyone.

I think it was almost two months ago now that Thomas Gleixner
indicated that security and privacy issues that we were raising with
respect to this driver, with what we believe is legitimate domain
expertise, threatened the upstreaming of the driver.  I think the case
can be made that those claims were somewhat specious given a fast
forward to today and the continued uncertainty regarding the
architecture of this driver.

So I will take that risk once again in order to provide some context
for this thread.

On Tue, Jun 30, 2020 at 10:49:56AM +0200, Borislav Petkov wrote:
> On Mon, Jun 29, 2020 at 03:04:00PM -0700, Sean Christopherson wrote:
> > > I don't see this acronym resolved anywhere in the whole patchset.
> > 
> > Quoting Enclave.

> Yah, pls add it somewhere.

For the benefit of everyone not deeply involved with this and perhaps
something that Jarkko can cut and paste if he desires.

The Quoting Enclave (QE) is the trusted endpoint that is responsible
for signing the report of an enclave's initialized status on a
platform.

In Enhanced Privacy ID (EPID) based attestation, the QE is the
custodian of one of the private EPID group keys that is provisioned to
the platform by the Intel Attestation Service (IAS).  The quoting
enclave generates a signature over the attesting enclave's report
structure using that key.  The IAS uses its public copy of the group
key to verify that the signature is from a trusted endpoint running on
a member of the group.

The EPID provisioning process 'trusts' that the platform, to which the
private group key is being delegated to, is a known Intel platform by
virtue of the fact that the Platform Certification Enclave (PCE) is
able to generate an identifier that could only be generated by having
access to a specific symmetric encryption key.  A key that is
available only to enclaves that have been initialized with the
PROVISION_KEY attribute bit.

The QE encrypts the private group key using a signer specific
(MRSIGNER) symmetric encryption key that only the QE can generate
while in a trusted initialization state.  That provides a mechanisum
for persisting this chain of trust outside the context of execution of
the QE.

Things are slightly different from a mechanistic perspective when the
Data Center Attestation Protocol (DCAP) is being used, but
conceptually the same.  In that attestation variant, the QE carries
the PROVISION_KEY attribute so that it can certify that the report
signature, generated with the Elliptic Curve Digital Signature
Algorithm (ECDSA) rather then EPID, is from a known platform.

> > /dev/sgx/provision is root-only by default, the expectation is
> > that the admin will configure the system to grant only specific
> > enclaves access to the PROVISION_KEY.

> Uuh, I don't like "the expectation is" - the reality happens to turn
> differently, more often than not.

Indeed, which is why we have consistently maintained that the platform
owner should be allowed to use cryptographic access controls over
which enclaves can possess the PROVISION_KEY attribute.

Given the security threat on a platform that is capable of supporting
Enclave Dynamic Memory Management (EDMM), the ability to initialize an
enclave is also a legitimate candidate for cryptographic access
control.

We can bikeshed the significance of these issues all day, but for the
record, access to the PROVISION_KEY allows platforms to be absolutely
and precisely fingerprinted for their entire lifespan.

Initialized enclaves on an EDMM capable platform have the ability to
execute arbitrary code, over which the kernel security infrastructure
has no visibility into or control over.

There is little doubt that EDMM will be a mainstay of the Confidential
Computing Initiative (CCI), which is the target of this driver.  A
review of the archives will indicate that RedHat/IBM has already
confirmed that their candidate for this infrastructure (Enarx)
requires EDMM.

To refresh everyone further, the last version of the SFLC patches that
we proposed, allows a platform owner to run the driver in a default
mode, which uses the proposed DAC controls over all of this or to opt
for stronger cryptographic controls.  The approach that we took has
virtually no impact on the architecture and footprint of the driver.

> > In this series, access is fairly binary, i.e. there's no
> > additional kernel infrastructure to help userspace make
> > per-enclave decisions.  There have been more than a few proposals
> > on how to extend the kernel to help provide better granularity,
> > e.g. LSM hooks, but it was generally agreed to punt that stuff to
> > post-upstreaming to keep things "simple" once we went far enough
> > down various paths to ensure we weren't painting ourselves into a
> > corner.

> So this all sounds to me like we should not upstream
> /dev/sgx/provision now but delay it until the infrastructure for
> that has been made more concrete. We can always add it
> then. Changing it after the fact - if we have to and for whatever
> reason - would be a lot harder for a user-visible interface which
> someone has started using already.
>
> So I'd leave that out from the initial patchset.

Without access to the PROVISION_KEY attribute, the two standard
mechanisms for attestation will not function, the technology is
arguably useless for its intended purposes without attestation.

Once again, I will leave it to community bike shedding as to whether
or not Linux wants the ability to support unfettered deterministic
platform fingerprinting that can be conducted for the physical
lifespan of the platform.

Once again, for the record, our approach affords compatibility with
the now 6+ year old out-of-tree user interface, without requiring its
use.  I would argue that the continually voiced concerns about
'painting ourselves into a corner', with respect to access
authorization, is significantly less of a problem with our approach
rather then without it.

> > If you want super gory details, Intel's whitepaper on attestation
> > in cloud environments is a good starting point[*], but I don't
> > recommended doing much more than skimming unless you really like
> > attestation stuff or are masochistic, which IMO amount to the same
> > thing :-)

> No thanks. :)

Interesting reflections and perhaps worthy of some introspection by
the Linux development community.

I will concede that there are a lot of musty corners that need to be
explored in order to understand how all of this works and the
security/privacy issues involved.  I certainly wouldn't wish
exploration on those corners on anyone.

I think everyone will concede that my ideas and suggestions on these
issues have been deemed to be unpopular, if not without merit.  They
do, however, come from the perspective of someone who directed a
complete and independent implementation of all of this infrastructure.

A process which has left me with no uncertainty whatsoever with
respect to the issues involved in all of this.

> Regards/Gruss,
>     Boris.

Best wishes for a pleasant and productive weekend to everyone.

Dr. Greg

As always,
Dr. Greg Wettstein, Ph.D, Worker      Autonomously self-defensive
Enjellic Systems Development, LLC     IOT platforms and edge devices.
4206 N. 19th Ave.
Fargo, ND  58102
PH: 701-281-1686                      EMAIL: greg@enjellic.com
------------------------------------------------------------------------------
"I suppose that could happen but he wouldn't know a Galois Field
 if it kicked him in the nuts."
                                -- Anonymous mathematician
                                   Resurrection.

Re: [PATCH v33 12/21] x86/sgx: Allow a limited use of ATTRIBUTE.PROVISIONKEY for attestation

[Jarkko Sakkinen]

On Mon, Jun 29, 2020 at 06:02:42PM +0200, Borislav Petkov wrote:
> On Thu, Jun 18, 2020 at 01:08:34AM +0300, Jarkko Sakkinen wrote:
> > Provisioning Certification Enclave (PCE), the root of trust for other
> > enclaves, generates a signing key from a fused key called Provisioning
> > Certification Key. PCE can then use this key to certify an attestation key
> > of a QE, e.g. we get the chain of trust down to the hardware if the Intel
> 
> What's a QE?
> 
> I don't see this acronym resolved anywhere in the whole patchset.

Quoting Enclave.

> 
> > signed PCE is used.
> > 
> > To use the needed keys, ATTRIBUTE.PROVISIONKEY is required but should be
> > only allowed for those who actually need it so that only the trusted
> > parties can certify QE's.
> > 
> > Obviously the attestation service should know the public key of the used
> > PCE and that way detect illegit attestation, but whitelisting the legit
> > users still adds an additional layer of defence.
> > 
> > Add new device file called /dev/sgx/provision. The sole purpose of this
> > file is to provide file descriptors that act as privilege tokens to allow
> > to build enclaves with ATTRIBUTE.PROVISIONKEY set. A new ioctl called
> > SGX_IOC_ENCLAVE_SET_ATTRIBUTE is used to assign this token to an enclave.
> 
> So I'm sure I'm missing something here: what controls which
> enclave can open /dev/sgx/provision and thus pass the FD to
> SGX_IOC_ENCLAVE_SET_ATTRIBUTE?
> 
> And in general, how does that whole flow look like: what calls
> SGX_IOC_ENCLAVE_SET_ATTRIBUTE when?

I've documented it in the Remote Attestation section:

https://github.com/jsakkine-intel/linux-sgx/blob/master/Documentation/x86/sgx.rst

/Jarkko

Re: [PATCH v33 12/21] x86/sgx: Allow a limited use of ATTRIBUTE.PROVISIONKEY for attestation

[Jarkko Sakkinen]

On Mon, Jun 29, 2020 at 03:04:00PM -0700, Sean Christopherson wrote:
> On Mon, Jun 29, 2020 at 06:02:42PM +0200, Borislav Petkov wrote:
> > On Thu, Jun 18, 2020 at 01:08:34AM +0300, Jarkko Sakkinen wrote:
> > > Provisioning Certification Enclave (PCE), the root of trust for other
> > > enclaves, generates a signing key from a fused key called Provisioning
> > > Certification Key. PCE can then use this key to certify an attestation key
> > > of a QE, e.g. we get the chain of trust down to the hardware if the Intel
> > 
> > What's a QE?
> > 
> > I don't see this acronym resolved anywhere in the whole patchset.
> 
> Quoting Enclave.
> 
> > > signed PCE is used.
> > > 
> > > To use the needed keys, ATTRIBUTE.PROVISIONKEY is required but should be
> > > only allowed for those who actually need it so that only the trusted
> > > parties can certify QE's.
> > > 
> > > Obviously the attestation service should know the public key of the used
> > > PCE and that way detect illegit attestation, but whitelisting the legit
> > > users still adds an additional layer of defence.
> > > 
> > > Add new device file called /dev/sgx/provision. The sole purpose of this
> > > file is to provide file descriptors that act as privilege tokens to allow
> > > to build enclaves with ATTRIBUTE.PROVISIONKEY set. A new ioctl called
> > > SGX_IOC_ENCLAVE_SET_ATTRIBUTE is used to assign this token to an enclave.
> > 
> > So I'm sure I'm missing something here: what controls which
> > enclave can open /dev/sgx/provision and thus pass the FD to
> > SGX_IOC_ENCLAVE_SET_ATTRIBUTE?
> 
> /dev/sgx/provision is root-only by default, the expectation is that the admin
> will configure the system to grant only specific enclaves access to the
> PROVISION_KEY.
> 
> > And in general, how does that whole flow look like: what calls
> > SGX_IOC_ENCLAVE_SET_ATTRIBUTE when?
> 
> The basic gist is that the host process of an enclave that needs/wants access
> to the PROVISION_KEY will invoke SGX_IOC_ENCLAVE_SET_ATTRIBUTE when building
> the enclave.  Any enclave can request access to PROVISION_KEY, but practically
> speaking only the PCE and QE (or their non-Intel equivalents) actually need
> access to the key.  KVM (future series) will also respect /dev/sgx/provision,
> i.e. require a similar ioctl() to expose the PROVISION_KEY to a guest.
> 
> E.g. for my own personal testing, I never do anything attestation related, so
> none of the enclaves I run request PROVISION_KEY, but I do expose it to VMs to
> test the KVM paths.
> 
> In this series, access is fairly binary, i.e. there's no additional kernel
> infrastructure to help userspace make per-enclave decisions.  There have been
> more than a few proposals on how to extend the kernel to help provide better
> granularity, e.g. LSM hooks, but it was generally agreed to punt that stuff
> to post-upstreaming to keep things "simple" once we went far enough down
> various paths to ensure we weren't painting ourselves into a corner.
> 
> If you want super gory details, Intel's whitepaper on attestation in cloud
> environments is a good starting point[*], but I don't recommended doing much
> more than skimming unless you really like attestation stuff or are
> masochistic, which IMO amount to the same thing :-)
> 
> [*] https://download.01.org/intel-sgx/dcap-1.0/docs/SGX_ECDSA_QuoteGenReference_DCAP_API_Linux_1.0.pdf

Section 3 in [*] is what describes the infrastructure. DCAP is only a
component in the whole attestation infrastructure.

[*] https://software.intel.com/sites/default/files/managed/f1/b8/intel-sgx-support-for-third-party-attestation.pdf

/Jarkko

Re: [PATCH v33 12/21] x86/sgx: Allow a limited use of ATTRIBUTE.PROVISIONKEY for attestation

[Jarkko Sakkinen]

On Tue, Jun 30, 2020 at 10:49:56AM +0200, Borislav Petkov wrote:
> On Mon, Jun 29, 2020 at 03:04:00PM -0700, Sean Christopherson wrote:
> > > I don't see this acronym resolved anywhere in the whole patchset.
> > 
> > Quoting Enclave.
> 
> Yah, pls add it somewhere.
> 
> > /dev/sgx/provision is root-only by default, the expectation is that the admin
> > will configure the system to grant only specific enclaves access to the
> > PROVISION_KEY.
> 
> Uuh, I don't like "the expectation is" - the reality happens to turn
> differently, more often than not.
> 
> > In this series, access is fairly binary, i.e. there's no additional kernel
> > infrastructure to help userspace make per-enclave decisions.  There have been
> > more than a few proposals on how to extend the kernel to help provide better
> > granularity, e.g. LSM hooks, but it was generally agreed to punt that stuff
> > to post-upstreaming to keep things "simple" once we went far enough down
> > various paths to ensure we weren't painting ourselves into a corner.
> 
> So this all sounds to me like we should not upstream /dev/sgx/provision
> now but delay it until the infrastructure for that has been made more
> concrete. We can always add it then. Changing it after the fact -
> if we have to and for whatever reason - would be a lot harder for a
> user-visible interface which someone has started using already.
> 
> So I'd leave  that out from the initial patchset.

I'm trying to understand what is meant by "more concrete". Attestation
is needed for most enclave applications.

If this patch is dropped, should we also allow PROVISION_KEY attribute
to all enclaves?  Dropping this patch and keeping that check in the
driver patch is not very coherent behaviour.

/Jarkko

Re: [PATCH v33 12/21] x86/sgx: Allow a limited use of ATTRIBUTE.PROVISIONKEY for attestation

[Jarkko Sakkinen]

On Fri, Jul 03, 2020 at 05:32:28AM +0300, Jarkko Sakkinen wrote:
> On Mon, Jun 29, 2020 at 06:02:42PM +0200, Borislav Petkov wrote:
> > On Thu, Jun 18, 2020 at 01:08:34AM +0300, Jarkko Sakkinen wrote:
> > > Provisioning Certification Enclave (PCE), the root of trust for other
> > > enclaves, generates a signing key from a fused key called Provisioning
> > > Certification Key. PCE can then use this key to certify an attestation key
> > > of a QE, e.g. we get the chain of trust down to the hardware if the Intel
> > 
> > What's a QE?
> > 
> > I don't see this acronym resolved anywhere in the whole patchset.
> 
> Quoting Enclave.

Thanks for spotting this. I updated my GIT-tree accordingly.

/Jarkko

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

[Jarkko Sakkinen]

On Fri, Jun 26, 2020 at 11:14:19AM +0200, Borislav Petkov wrote:
> On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:
> > diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
> > index 59472cd6a11d..35f713e3a267 100644
> > --- a/Documentation/userspace-api/ioctl/ioctl-number.rst
> > +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
> > @@ -323,6 +323,7 @@ Code  Seq#    Include File                                           Comments
> >                                                                       <mailto:tlewis@mindspring.com>
> >  0xA3  90-9F  linux/dtlk.h
> >  0xA4  00-1F  uapi/linux/tee.h                                        Generic TEE subsystem
> > +0xA4  00-1F  uapi/asm/sgx.h                                          Intel SGX subsystem (a legit conflict as TEE and SGX do not co-exist)
> 
> Maybe add <mailto:linux-sgx@vger.kernel.org> ?
> 
> >  0xAA  00-3F  linux/uapi/linux/userfaultfd.h
> >  0xAB  00-1F  linux/nbd.h
> >  0xAC  00-1F  linux/raw.h
> 
> ...
> 
> > +static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs)
> > +{
> > +	unsigned long encl_size = secs->size + PAGE_SIZE;
> 
> Wait, you just copied @secs from user memory in sgx_ioc_enclave_create()
> and now use ->size unverified? You're kidding, right?

The validation is done in sgx_validate_secs().

> 
> > +	struct sgx_epc_page *secs_epc;
> > +	unsigned long ssaframesize;
> > +	struct sgx_pageinfo pginfo;
> > +	struct sgx_secinfo secinfo;
> > +	struct file *backing;
> > +	long ret;
> > +
> > +	if (atomic_read(&encl->flags) & SGX_ENCL_CREATED)
> > +		return -EINVAL;
> > +
> > +	ssaframesize = sgx_calc_ssaframesize(secs->miscselect, secs->xfrm);
> 
> So this is using more un-validated user input to do further calculations.
> What can possibly go wrong?
> 
> I sure hope *I* am wrong and am missing something here.
> 
> If not, please, for the next version, audit all your user input and
> validate it before using it. Srsly.

It works but is unclean. I'd guess reason for this is just that code has
evolved into this state over time.

I'd just move the call to sgx_calc_ssaframesize() inside
sgx_validate_secs().

/Jarkko

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

[Jarkko Sakkinen]

On Fri, Jun 26, 2020 at 04:20:19PM +0200, Borislav Petkov wrote:
> On Fri, Jun 26, 2020 at 07:16:27AM -0700, Sean Christopherson wrote:
> > That being said, I agree that it would be safer to move sgx_calc_ssaframesize()
> > inside sgx_validate_secs() and only compute encl_size after the secs is
> > validated.
> 

Changed as

if (!secs->ssa_frame_size)
	return -EINVAL;

if (sgx_calc_ssa_frame_size(secs->miscselect, secs->xfrm) >
    secs->ssa_frame_size)
	return -EINVAL;

/Jarkko

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

[Jarkko Sakkinen]

On Fri, Jun 26, 2020 at 05:34:00PM +0200, Borislav Petkov wrote:
> On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:
> 
> ...
> 
> This could use some commenting along the lines of:
> 
> "— If the enclave developer requires measurement of the page as a
> proof for the content, use EEXTEND to add a measurement for 256 bytes of
> the page. Repeat this operation until the entire page is measured."
> 
> At least this text from the SDM maps to the 256 bytes below. Otherwise
> it is magic.

Copied with pride:

/*
 * If the caller requires measurement of the page as a proof for the content,
 * use EEXTEND to add a measurement for 256 bytes of the page. Repeat this
 * operation until the entire page is measured."
 */

> > +static int sgx_encl_add_page(struct sgx_encl *encl, unsigned long src,
> > +			     unsigned long offset, unsigned long length,
> > +			     struct sgx_secinfo *secinfo, unsigned long flags)
> > +{
> > +	struct sgx_encl_page *encl_page;
> > +	struct sgx_epc_page *epc_page;
> > +	int ret;
> > +
> > +	encl_page = sgx_encl_page_alloc(encl, offset, secinfo->flags);
> > +	if (IS_ERR(encl_page))
> > +		return PTR_ERR(encl_page);
> > +
> > +	epc_page = __sgx_alloc_epc_page();
> > +	if (IS_ERR(epc_page)) {
> > +		kfree(encl_page);
> > +		return PTR_ERR(epc_page);
> > +	}
> > +
> > +	if (atomic_read(&encl->flags) &
> > +	    (SGX_ENCL_INITIALIZED | SGX_ENCL_DEAD)) {
> > +		ret = -EFAULT;
> > +		goto err_out_free;
> > +	}
> 
> You can do this first thing when you enter the function so that
> you don't have to allocate needlessly in the error case, when
> SGX_ENCL_INITIALIZED | SGX_ENCL_DEAD is set.

Updated version:

static int sgx_encl_add_page(struct sgx_encl *encl, unsigned long src,
			     unsigned long offset, unsigned long length,
			     struct sgx_secinfo *secinfo, unsigned long flags)
{
	struct sgx_encl_page *encl_page;
	struct sgx_epc_page *epc_page;
	struct sgx_va_page *va_page;
	int ret;

	if (atomic_read(&encl->flags) & SGX_ENCL_INITIALIZED)
		return -EFAULT;

SGX_ENCL_DEAD check is unnecessary altogether as this flag cannot be
possibly be unset inside ioctl. 'sgx_release()' will set it which is
the release callback for the enclave file.

'sgx_ioctl()' also unnecessarily has this check I just noticed (and
removed).

> "uninitialized"?
> 
> Where is the test for SGX_ENCL_INITIALIZED and erroring out otherwise?
> 
> I.e., what happens if you add pages to an initialized enclave?

Because of historical reasons it is in sgx_encl_add_page(). Then we
allowed ioctl's operate on enclave concurrently. Today we enforce
sequential operation on a single enclave with SGX_ENCL_IOCTL flag
because that is the only sane way to use the construction operations.

Therefore the check can be moved to sgx_ioc_encl_add_pages() if you
request so but first I have one remark to discuss.

I noticed that sometimes wrong state flags turn into -EINVAL and
sometimes into -EFAULT (like in the previous case). I'd suggest
that when the ioctl is blocked based encl->flags and only on that,
the ioctl would return -ENOIOCTLCMD in both cases, i.e. this
command is not available.

That would give much better aids for debugging user space code.

> 
> > + * measurement with the contents of the page. The address range of pages must
> > + * be contiguous.
> 
> Must? Who is enforcing this? I'm trying to find where...

Unfortunately I cannot recall what I meant when I wrote that. I removed
that sentence. I'm not sure what I meant exactly when I used 'contiguous'
here.

> > The SECINFO and measurement mask are applied to all pages.
> > + *
> > + * A SECINFO for a TCS is required to always contain zero permissions because
> > + * CPU silently zeros them. Allowing anything else would cause a mismatch in
> > + * the measurement.
> > + *
> > + * mmap()'s protection bits are capped by the page permissions. For each page
> > + * address, the maximum protection bits are computed with the following
> > + * heuristics:
> > + *
> > + * 1. A regular page: PROT_R, PROT_W and PROT_X match the SECINFO permissions.
> > + * 2. A TCS page: PROT_R | PROT_W.
> > + *
> > + * mmap() is not allowed to surpass the minimum of the maximum protection bits
> > + * within the given address range.
> > + *
> > + * If ENCLS opcode fails, that effectively means that EPC has been invalidated.
> > + * When this happens the enclave is destroyed and -EIO is returned to the
> > + * caller.
> > + *
> > + * Return:
> > + *   0 on success,
> > + *   -EACCES if an executable source page is located in a noexec partition,
> > + *   -EIO if either ENCLS[EADD] or ENCLS[EEXTEND] fails
> > + *   -errno otherwise
> > + */
> > +static long sgx_ioc_enclave_add_pages(struct sgx_encl *encl, void __user *arg)
> > +{
> > +	struct sgx_enclave_add_pages addp;
> > +	struct sgx_secinfo secinfo;
> > +	unsigned long c;
> > +	int ret;
> > +
> > +	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...

SGX_IOC_ENCLAVE_CREATE defines the address range, and thus sets the
limit on how many pages in total can be added to the enclave.

sgx_encl_size_max_64 contains the maximum size for the address range
and is initialized as follows:

cpuid_count(SGX_CPUID, 0, &eax, &ebx, &ecx, &edx);
sgx_encl_size_max_64 = 1ULL << ((edx >> 8) & 0xFF);

[derived from sgx_drv_init()]

> > +
> > +	if (addp.offset + addp.length - PAGE_SIZE >= encl->size)
> > +		return -EINVAL;
> > +
> > +	if (copy_from_user(&secinfo, (void __user *)addp.secinfo,
> > +			   sizeof(secinfo)))
> > +		return -EFAULT;
> > +
> > +	if (sgx_validate_secinfo(&secinfo))
> > +		return -EINVAL;
> > +
> > +	for (c = 0 ; c < addp.length; c += PAGE_SIZE) {
> > +		if (signal_pending(current)) {
> > +			ret = -EINTR;
> > +			break;
> > +		}
> > +
> > +		if (need_resched())
> > +			cond_resched();
> > +
> > +		ret = sgx_encl_add_page(encl, addp.src + c, addp.offset + c,
> > +					addp.length - c, &secinfo, addp.flags);
> > +		if (ret)
> > +			break;
> > +	}
> > +
> > +	addp.count = c;

If you referred with your previous question, how to limit the number of
pages that this ioctl can process in one run, it is already supported
in the API with 'addp.count'.

It'd be possible to add this if required:

addp.length = min(addp.length, SGX_ENCLAVE_IOC_ADD_PAGES_MAX_LENGTH));

/Jarkko

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

[Jarkko Sakkinen]

On Sat, Jun 27, 2020 at 07:43:35PM +0200, Borislav Petkov wrote:
> On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:
> > +static int sgx_encl_init(struct sgx_encl *encl, struct sgx_sigstruct *sigstruct,
> > +			 void *token)
> > +{
> > +	u64 mrsigner[4];
> > +	int ret;
> > +	int i;
> > +	int j;
> > +
> > +	/* Check that the required attributes have been authorized. */
> > +	if (encl->secs_attributes & ~encl->allowed_attributes)
> > +		return -EACCES;
> > +
> > +	ret = sgx_get_key_hash(sigstruct->modulus, mrsigner);
> > +	if (ret)
> > +		return ret;
> > +
> > +	mutex_lock(&encl->lock);
> > +
> > +	if (atomic_read(&encl->flags) & SGX_ENCL_INITIALIZED) {
> > +		ret = -EFAULT;
> > +		goto err_out;
> > +	}
> 
> That test should be the first thing this function or its caller does.

Fixed.

> 
> > +	for (i = 0; i < SGX_EINIT_SLEEP_COUNT; i++) {
> > +		for (j = 0; j < SGX_EINIT_SPIN_COUNT; j++) {
> 
> Ew, what's that double-loop for?
> 
> It tries to init an enclave a bunch of times. Why does it need to init
> more than once?

From SDM:

"Periodically, EINIT polls for certain asynchronous events. If such an
event is detected, it completes with failure code (ZF=1 and RAX =
SGX_UNMASKED_EVENT), and RIP is incremented to point to the next
instruction. These events includes external interrupts, non-maskable
interrupts, system-management interrupts, machine checks, INIT signals,
and the VMX-preemption timer. EINIT does not fail if the pending event
is inhibited (e.g., external interrupts could be inhibited due to
blocking by MOV SS blocking or by STI)."

Not exactly sure though why this must be polled inside the kernel though.

> 
> > +			ret = sgx_einit(sigstruct, token, encl->secs.epc_page,
> > +					mrsigner);
> > +			if (ret == SGX_UNMASKED_EVENT)
> > +				continue;
> > +			else
> > +				break;
> > +		}
> > +
> > +		if (ret != SGX_UNMASKED_EVENT)
> > +			break;
> > +
> > +		msleep_interruptible(SGX_EINIT_SLEEP_TIME);
> > +
> > +		if (signal_pending(current)) {
> > +			ret = -ERESTARTSYS;
> > +			goto err_out;
> > +		}
> > +	}
> > +
> > +	if (ret & ENCLS_FAULT_FLAG) {
> > +		if (encls_failed(ret))
> > +			ENCLS_WARN(ret, "EINIT");
> > +
> > +		sgx_encl_destroy(encl);
> > +		ret = -EFAULT;
> > +	} else if (ret) {
> > +		pr_debug("EINIT returned %d\n", ret);
> > +		ret = -EPERM;
> > +	} else {
> > +		atomic_or(SGX_ENCL_INITIALIZED, &encl->flags);
> > +	}
> > +
> > +err_out:
> > +	mutex_unlock(&encl->lock);
> > +	return ret;
> > +}
> > +
> > +/**
> > + * sgx_ioc_enclave_init - handler for %SGX_IOC_ENCLAVE_INIT
> > + *
> > + * @filep:	open file to /dev/sgx
> 
> @encl:       pointer to an enclave instance (via ioctl() file pointer)
> 
> > + * @arg:	userspace pointer to a struct sgx_enclave_init instance
> > + *
> > + * Flush any outstanding enqueued EADD operations and perform EINIT.  The
> > + * Launch Enclave Public Key Hash MSRs are rewritten as necessary to match
> > + * the enclave's MRSIGNER, which is caculated from the provided sigstruct.
> > + *
> > + * Return:
> > + *   0 on success,
> > + *   SGX error code on EINIT failure,
> > + *   -errno otherwise
> > + */
> > +static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg)
> > +{
> > +	struct sgx_sigstruct *sigstruct;
> > +	struct sgx_enclave_init einit;
> > +	struct page *initp_page;
> > +	void *token;
> > +	int ret;
> > +
> > +	if (!(atomic_read(&encl->flags) & SGX_ENCL_CREATED))
> 
> Might just as well check the other flags: doing EINIT on an already
> initialized enclave - SGX_ENCL_INITIALIZED - is perhaps a nono or
> similarly on a SGX_ENCL_DEAD enclave.
> 
> And you could do similar sanity checks in the other ioctl functions.

Agreed (see my earlier response, let's continue this discussion there).

/Jarkko

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

[Jarkko Sakkinen]

On Mon, Jun 29, 2020 at 08:27:19AM -0700, Sean Christopherson wrote:
> On Sat, Jun 27, 2020 at 07:43:35PM +0200, Borislav Petkov wrote:
> > On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:
> > > +static int sgx_encl_init(struct sgx_encl *encl, struct sgx_sigstruct *sigstruct,
> > > +			 void *token)
> > > +{
> > > +	u64 mrsigner[4];
> > > +	int ret;
> > > +	int i;
> > > +	int j;
> > > +
> > > +	/* Check that the required attributes have been authorized. */
> > > +	if (encl->secs_attributes & ~encl->allowed_attributes)
> > > +		return -EACCES;
> > > +
> > > +	ret = sgx_get_key_hash(sigstruct->modulus, mrsigner);
> > > +	if (ret)
> > > +		return ret;
> > > +
> > > +	mutex_lock(&encl->lock);
> > > +
> > > +	if (atomic_read(&encl->flags) & SGX_ENCL_INITIALIZED) {
> > > +		ret = -EFAULT;
> > > +		goto err_out;
> > > +	}
> > 
> > That test should be the first thing this function or its caller does.
> 
> Hmm, I was going to say that SGX_ENCL_INITIALIZED can't be checked until
> encl->lock is held, but that's not true for this path as mutual exclusion
> is provided by the SGX_ENCL_IOCTL flag.  So yeah, this can be checked at
> the same time as SGX_ENCL_CREATED in sgx_ioc_enclave_init().
> 
> > > +	for (i = 0; i < SGX_EINIT_SLEEP_COUNT; i++) {
> > > +		for (j = 0; j < SGX_EINIT_SPIN_COUNT; j++) {
> > 
> > Ew, what's that double-loop for?
> > 
> > It tries to init an enclave a bunch of times. Why does it need to init
> > more than once?
> 
> ENCLS[EINIT] is interruptible because it has such a high latency, e.g. 50k+
> cycles on success.  If an IRQ/NMI/SMI becomes pending, EINIT may fail with
> SGX_UNMASKED_EVENT so that the event can be serviced.
> 
> The idea behind the double loop is to try EINIT in a tight loop, then back
> off and sleep for a while before retrying that tight inner loop.
> 
> > > +			ret = sgx_einit(sigstruct, token, encl->secs.epc_page,
> > > +					mrsigner);
> > > +			if (ret == SGX_UNMASKED_EVENT)
> > > +				continue;
> > > +			else
> > > +				break;
> > > +		}
> > > +
> > > +		if (ret != SGX_UNMASKED_EVENT)
> > > +			break;
> > > +
> > > +		msleep_interruptible(SGX_EINIT_SLEEP_TIME);
> > > +
> > > +		if (signal_pending(current)) {
> > > +			ret = -ERESTARTSYS;
> > > +			goto err_out;
> > > +		}
> > > +	}
> > > +
> > > +	if (ret & ENCLS_FAULT_FLAG) {
> > > +		if (encls_failed(ret))
> > > +			ENCLS_WARN(ret, "EINIT");
> > > +
> > > +		sgx_encl_destroy(encl);
> > > +		ret = -EFAULT;
> > > +	} else if (ret) {
> > > +		pr_debug("EINIT returned %d\n", ret);
> > > +		ret = -EPERM;
> > > +	} else {
> > > +		atomic_or(SGX_ENCL_INITIALIZED, &encl->flags);
> > > +	}
> > > +
> > > +err_out:
> > > +	mutex_unlock(&encl->lock);
> > > +	return ret;
> > > +}
> > > +
> > > +/**
> > > + * sgx_ioc_enclave_init - handler for %SGX_IOC_ENCLAVE_INIT
> > > + *
> > > + * @filep:	open file to /dev/sgx
> > 
> > @encl:       pointer to an enclave instance (via ioctl() file pointer)
> > 
> > > + * @arg:	userspace pointer to a struct sgx_enclave_init instance
> > > + *
> > > + * Flush any outstanding enqueued EADD operations and perform EINIT.  The
> > > + * Launch Enclave Public Key Hash MSRs are rewritten as necessary to match
> > > + * the enclave's MRSIGNER, which is caculated from the provided sigstruct.
> > > + *
> > > + * Return:
> > > + *   0 on success,
> > > + *   SGX error code on EINIT failure,
> > > + *   -errno otherwise
> > > + */
> > > +static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg)
> > > +{
> > > +	struct sgx_sigstruct *sigstruct;
> > > +	struct sgx_enclave_init einit;
> > > +	struct page *initp_page;
> > > +	void *token;
> > > +	int ret;
> > > +
> > > +	if (!(atomic_read(&encl->flags) & SGX_ENCL_CREATED))
> > 
> > Might just as well check the other flags: doing EINIT on an already
> > initialized enclave - SGX_ENCL_INITIALIZED - is perhaps a nono or
> > similarly on a SGX_ENCL_DEAD enclave.
> > 
> > And you could do similar sanity checks in the other ioctl functions.
> 
> Ya, as above, SGX_ENCL_INITIALIZED can be checked here.
> 
> SGX_ENCL_DEAD is actually already checked in in the top level sgx_ioctl(),
> i.e. the check in sgx_encl_add_page() can technically be flat out dropped.
> 
> I say "technically" because I'm a bit torn over SGX_ENCL_DEAD; encl->lock
> must be held to SGX_ENCL_DEAD (the page fault and reclaim flows rely on
> this), but as it stands today only ioctl() paths (guarded by SGX_ENCL_IOCTL)
> and sgx_release() (makes the ioctls() unreachable) set SGX_ENCL_DEAD.
> 
> So it's safe to check SGX_ENCL_DEAD from ioctl() context without holding
> encl->lock, at least in the current code base, but it feels weird/sketchy.
> 
> In the end I don't think I have a strong opinion.  Removing the technically
> unnecessary DEAD check in sgx_encl_add_page() is the simplest change, so it
> may make sense to do that and nothing more for initial upstreaming.  Long
> term, I fully expect we'll add paths that set SGX_ENCL_DEAD outside of
> ioctl() context, e.g. to handle EPC OOM, but it wouldn't be a bad thing to
> have a standalone commit in a future series to add DEAD checks (under
> encl->lock) in the ADD and INIT flows.

AFAIK nonne of th ioctl's should not need SGX_ENCL_DEAD check.

/Jarkko

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

[Jarkko Sakkinen]

On Wed, Jul 01, 2020 at 08:59:02PM -0700, Sean Christopherson wrote:
> On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:
> > +static int sgx_validate_secs(const struct sgx_secs *secs,
> > +			     unsigned long ssaframesize)
> > +{
> > +	if (secs->size < (2 * PAGE_SIZE) || !is_power_of_2(secs->size))
> > +		return -EINVAL;
> > +
> > +	if (secs->base & (secs->size - 1))
> > +		return -EINVAL;
> > +
> > +	if (secs->miscselect & sgx_misc_reserved_mask ||
> > +	    secs->attributes & sgx_attributes_reserved_mask ||
> > +	    secs->xfrm & sgx_xfrm_reserved_mask)
> > +		return -EINVAL;
> > +
> > +	if (secs->attributes & SGX_ATTR_MODE64BIT) {
> > +		if (secs->size > sgx_encl_size_max_64)
> > +			return -EINVAL;
> > +	} else if (secs->size > sgx_encl_size_max_32)
> > +		return -EINVAL;
> 
> These should be >=, not >, the SDM uses one of those fancy ≥ ligatures.
> 
> Internal versions use more obvious pseudocode, e.g.:
> 
>     if ((DS:TMP_SECS.ATTRIBUTES.MODE64BIT = 1) AND
>         (DS:TMP_SECS.SIZE AND (~((1 << CPUID.18.0:EDX[15:8]) – 1)))
>     {
>         #GP(0);

Updated as:

static int sgx_validate_secs(const struct sgx_secs *secs)
{
	u64 max_size = (secs->attributes & SGX_ATTR_MODE64BIT) ?
		       sgx_encl_size_max_64 : sgx_encl_size_max_32;

	if (secs->size < (2 * PAGE_SIZE) || !is_power_of_2(secs->size))
		return -EINVAL;

	if (secs->base & (secs->size - 1))
		return -EINVAL;

	if (secs->miscselect & sgx_misc_reserved_mask ||
	    secs->attributes & sgx_attributes_reserved_mask ||
	    secs->xfrm & sgx_xfrm_reserved_mask)
		return -EINVAL;

	if (secs->size >= max_size)
		return -EINVAL;

/Jarkko

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

[Sean Christopherson]

On Sat, Jul 04, 2020 at 04:43:49AM +0300, Jarkko Sakkinen wrote:
> On Mon, Jun 29, 2020 at 08:27:19AM -0700, Sean Christopherson wrote:
> > On Sat, Jun 27, 2020 at 07:43:35PM +0200, Borislav Petkov wrote:
> > > And you could do similar sanity checks in the other ioctl functions.
> > 
> > Ya, as above, SGX_ENCL_INITIALIZED can be checked here.
> > 
> > SGX_ENCL_DEAD is actually already checked in in the top level sgx_ioctl(),
> > i.e. the check in sgx_encl_add_page() can technically be flat out dropped.
> > 
> > I say "technically" because I'm a bit torn over SGX_ENCL_DEAD; encl->lock
> > must be held to SGX_ENCL_DEAD (the page fault and reclaim flows rely on
> > this), but as it stands today only ioctl() paths (guarded by SGX_ENCL_IOCTL)
> > and sgx_release() (makes the ioctls() unreachable) set SGX_ENCL_DEAD.
> > 
> > So it's safe to check SGX_ENCL_DEAD from ioctl() context without holding
> > encl->lock, at least in the current code base, but it feels weird/sketchy.
> > 
> > In the end I don't think I have a strong opinion.  Removing the technically
> > unnecessary DEAD check in sgx_encl_add_page() is the simplest change, so it
> > may make sense to do that and nothing more for initial upstreaming.  Long
> > term, I fully expect we'll add paths that set SGX_ENCL_DEAD outside of
> > ioctl() context, e.g. to handle EPC OOM, but it wouldn't be a bad thing to
> > have a standalone commit in a future series to add DEAD checks (under
> > encl->lock) in the ADD and INIT flows.
> 
> AFAIK nonne of th ioctl's should not need SGX_ENCL_DEAD check.

I can't tell if the double negative was intended, but I took a peek at your
current master and see that you removed the SGX_ENCL_DEAD check in
sgx_ioctl().  That check needs to stay, e.g. if EEXTEND fails we absolutely
need to prevent any further operations on the enclave.

The above was calling out that additional checks on SGX_ENCL_DEAD after
acquiring encl->lock are not necessary because SGX_ENCL_DEAD can only be
set when the ioctls() are no longer reachable or from within an ioctl(),
which provides exclusivity via SGX_ENCL_IOCTL.

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

[Jarkko Sakkinen]

On Mon, Jul 06, 2020 at 06:38:47PM -0700, Sean Christopherson wrote:
> On Sat, Jul 04, 2020 at 04:43:49AM +0300, Jarkko Sakkinen wrote:
> > On Mon, Jun 29, 2020 at 08:27:19AM -0700, Sean Christopherson wrote:
> > > On Sat, Jun 27, 2020 at 07:43:35PM +0200, Borislav Petkov wrote:
> > > > And you could do similar sanity checks in the other ioctl functions.
> > > 
> > > Ya, as above, SGX_ENCL_INITIALIZED can be checked here.
> > > 
> > > SGX_ENCL_DEAD is actually already checked in in the top level sgx_ioctl(),
> > > i.e. the check in sgx_encl_add_page() can technically be flat out dropped.
> > > 
> > > I say "technically" because I'm a bit torn over SGX_ENCL_DEAD; encl->lock
> > > must be held to SGX_ENCL_DEAD (the page fault and reclaim flows rely on
> > > this), but as it stands today only ioctl() paths (guarded by SGX_ENCL_IOCTL)
> > > and sgx_release() (makes the ioctls() unreachable) set SGX_ENCL_DEAD.
> > > 
> > > So it's safe to check SGX_ENCL_DEAD from ioctl() context without holding
> > > encl->lock, at least in the current code base, but it feels weird/sketchy.
> > > 
> > > In the end I don't think I have a strong opinion.  Removing the technically
> > > unnecessary DEAD check in sgx_encl_add_page() is the simplest change, so it
> > > may make sense to do that and nothing more for initial upstreaming.  Long
> > > term, I fully expect we'll add paths that set SGX_ENCL_DEAD outside of
> > > ioctl() context, e.g. to handle EPC OOM, but it wouldn't be a bad thing to
> > > have a standalone commit in a future series to add DEAD checks (under
> > > encl->lock) in the ADD and INIT flows.
> > 
> > AFAIK nonne of th ioctl's should not need SGX_ENCL_DEAD check.
> 
> I can't tell if the double negative was intended, but I took a peek at your
> current master and see that you removed the SGX_ENCL_DEAD check in
> sgx_ioctl().  That check needs to stay, e.g. if EEXTEND fails we absolutely
> need to prevent any further operations on the enclave.
> 
> The above was calling out that additional checks on SGX_ENCL_DEAD after
> acquiring encl->lock are not necessary because SGX_ENCL_DEAD can only be
> set when the ioctls() are no longer reachable or from within an ioctl(),
> which provides exclusivity via SGX_ENCL_IOCTL.

Got it.

/Jarkko

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

[Haitao Huang]

On Fri, 03 Jul 2020 22:31:10 -0500, Jarkko Sakkinen  
<jarkko.sakkinen@linux.intel.com> wrote:

> On Wed, Jul 01, 2020 at 08:59:02PM -0700, Sean Christopherson wrote:
>> On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:
>> > +static int sgx_validate_secs(const struct sgx_secs *secs,
>> > +			     unsigned long ssaframesize)
>> > +{
>> > +	if (secs->size < (2 * PAGE_SIZE) || !is_power_of_2(secs->size))
>> > +		return -EINVAL;
>> > +
>> > +	if (secs->base & (secs->size - 1))
>> > +		return -EINVAL;
>> > +
>> > +	if (secs->miscselect & sgx_misc_reserved_mask ||
>> > +	    secs->attributes & sgx_attributes_reserved_mask ||
>> > +	    secs->xfrm & sgx_xfrm_reserved_mask)
>> > +		return -EINVAL;
>> > +
>> > +	if (secs->attributes & SGX_ATTR_MODE64BIT) {
>> > +		if (secs->size > sgx_encl_size_max_64)
>> > +			return -EINVAL;
>> > +	} else if (secs->size > sgx_encl_size_max_32)
>> > +		return -EINVAL;
>>
>> These should be >=, not >, the SDM uses one of those fancy ≥ ligatures.
>>
>> Internal versions use more obvious pseudocode, e.g.:
>>
>>     if ((DS:TMP_SECS.ATTRIBUTES.MODE64BIT = 1) AND
>>         (DS:TMP_SECS.SIZE AND (~((1 << CPUID.18.0:EDX[15:8]) – 1)))
>>     {
>>         #GP(0);
>
> Updated as:
>
> static int sgx_validate_secs(const struct sgx_secs *secs)
> {
> 	u64 max_size = (secs->attributes & SGX_ATTR_MODE64BIT) ?
> 		       sgx_encl_size_max_64 : sgx_encl_size_max_32;
>
> 	if (secs->size < (2 * PAGE_SIZE) || !is_power_of_2(secs->size))
> 		return -EINVAL;
>
> 	if (secs->base & (secs->size - 1))
> 		return -EINVAL;
>
> 	if (secs->miscselect & sgx_misc_reserved_mask ||
> 	    secs->attributes & sgx_attributes_reserved_mask ||
> 	    secs->xfrm & sgx_xfrm_reserved_mask)
> 		return -EINVAL;
>
> 	if (secs->size >= max_size)
> 		return -EINVAL;
>

This should be > not >=. Issue raised and fixed by Fábio Silva for ported  
patches for OOT SGX support:  
https://github.com/intel/SGXDataCenterAttestationPrimitives/pull/123

I tested and verified with Intel arch, the comparison indeed should be >.

Thanks
Haitao

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

[Sean Christopherson]

On Tue, Sep 01, 2020 at 10:06:32PM -0500, Haitao Huang wrote:
> On Fri, 03 Jul 2020 22:31:10 -0500, Jarkko Sakkinen
> <jarkko.sakkinen@linux.intel.com> wrote:
> 
> > On Wed, Jul 01, 2020 at 08:59:02PM -0700, Sean Christopherson wrote:
> > > On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:
> > > > +static int sgx_validate_secs(const struct sgx_secs *secs,
> > > > +			     unsigned long ssaframesize)
> > > > +{
> > > > +	if (secs->size < (2 * PAGE_SIZE) || !is_power_of_2(secs->size))
> > > > +		return -EINVAL;
> > > > +
> > > > +	if (secs->base & (secs->size - 1))
> > > > +		return -EINVAL;
> > > > +
> > > > +	if (secs->miscselect & sgx_misc_reserved_mask ||
> > > > +	    secs->attributes & sgx_attributes_reserved_mask ||
> > > > +	    secs->xfrm & sgx_xfrm_reserved_mask)
> > > > +		return -EINVAL;
> > > > +
> > > > +	if (secs->attributes & SGX_ATTR_MODE64BIT) {
> > > > +		if (secs->size > sgx_encl_size_max_64)
> > > > +			return -EINVAL;
> > > > +	} else if (secs->size > sgx_encl_size_max_32)
> > > > +		return -EINVAL;
> > > 
> > > These should be >=, not >, the SDM uses one of those fancy ≥ ligatures.
> > > 
> > > Internal versions use more obvious pseudocode, e.g.:
> > > 
> > >     if ((DS:TMP_SECS.ATTRIBUTES.MODE64BIT = 1) AND
> > >         (DS:TMP_SECS.SIZE AND (~((1 << CPUID.18.0:EDX[15:8]) – 1)))
> > >     {
> > >         #GP(0);
> > 
> > Updated as:
> > 
> > static int sgx_validate_secs(const struct sgx_secs *secs)
> > {
> > 	u64 max_size = (secs->attributes & SGX_ATTR_MODE64BIT) ?
> > 		       sgx_encl_size_max_64 : sgx_encl_size_max_32;
> > 
> > 	if (secs->size < (2 * PAGE_SIZE) || !is_power_of_2(secs->size))
> > 		return -EINVAL;
> > 
> > 	if (secs->base & (secs->size - 1))
> > 		return -EINVAL;
> > 
> > 	if (secs->miscselect & sgx_misc_reserved_mask ||
> > 	    secs->attributes & sgx_attributes_reserved_mask ||
> > 	    secs->xfrm & sgx_xfrm_reserved_mask)
> > 		return -EINVAL;
> > 
> > 	if (secs->size >= max_size)
> > 		return -EINVAL;
> > 
> 
> This should be > not >=. Issue raised and fixed by Fábio Silva for ported
> patches for OOT SGX support:
> https://github.com/intel/SGXDataCenterAttestationPrimitives/pull/123
> 
> I tested and verified with Intel arch, the comparison indeed should be >.

And this is a confirmed SDM bug, correct?

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

[Haitao Huang]

On Wed, 02 Sep 2020 11:10:12 -0500, Sean Christopherson  
<sean.j.christopherson@intel.com> wrote:

> On Tue, Sep 01, 2020 at 10:06:32PM -0500, Haitao Huang wrote:
>> On Fri, 03 Jul 2020 22:31:10 -0500, Jarkko Sakkinen
>> <jarkko.sakkinen@linux.intel.com> wrote:
>>
>> > On Wed, Jul 01, 2020 at 08:59:02PM -0700, Sean Christopherson wrote:
>> > > On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:
>> > > > +static int sgx_validate_secs(const struct sgx_secs *secs,
>> > > > +			     unsigned long ssaframesize)
>> > > > +{
>> > > > +	if (secs->size < (2 * PAGE_SIZE) || !is_power_of_2(secs->size))
>> > > > +		return -EINVAL;
>> > > > +
>> > > > +	if (secs->base & (secs->size - 1))
>> > > > +		return -EINVAL;
>> > > > +
>> > > > +	if (secs->miscselect & sgx_misc_reserved_mask ||
>> > > > +	    secs->attributes & sgx_attributes_reserved_mask ||
>> > > > +	    secs->xfrm & sgx_xfrm_reserved_mask)
>> > > > +		return -EINVAL;
>> > > > +
>> > > > +	if (secs->attributes & SGX_ATTR_MODE64BIT) {
>> > > > +		if (secs->size > sgx_encl_size_max_64)
>> > > > +			return -EINVAL;
>> > > > +	} else if (secs->size > sgx_encl_size_max_32)
>> > > > +		return -EINVAL;
>> > >
>> > > These should be >=, not >, the SDM uses one of those fancy ≥  
>> ligatures.
>> > >
>> > > Internal versions use more obvious pseudocode, e.g.:
>> > >
>> > >     if ((DS:TMP_SECS.ATTRIBUTES.MODE64BIT = 1) AND
>> > >         (DS:TMP_SECS.SIZE AND (~((1 << CPUID.18.0:EDX[15:8]) – 1)))
>> > >     {
>> > >         #GP(0);
>> >
>> > Updated as:
>> >
>> > static int sgx_validate_secs(const struct sgx_secs *secs)
>> > {
>> > 	u64 max_size = (secs->attributes & SGX_ATTR_MODE64BIT) ?
>> > 		       sgx_encl_size_max_64 : sgx_encl_size_max_32;
>> >
>> > 	if (secs->size < (2 * PAGE_SIZE) || !is_power_of_2(secs->size))
>> > 		return -EINVAL;
>> >
>> > 	if (secs->base & (secs->size - 1))
>> > 		return -EINVAL;
>> >
>> > 	if (secs->miscselect & sgx_misc_reserved_mask ||
>> > 	    secs->attributes & sgx_attributes_reserved_mask ||
>> > 	    secs->xfrm & sgx_xfrm_reserved_mask)
>> > 		return -EINVAL;
>> >
>> > 	if (secs->size >= max_size)
>> > 		return -EINVAL;
>> >
>>
>> This should be > not >=. Issue raised and fixed by Fábio Silva for  
>> ported
>> patches for OOT SGX support:
>> https://github.com/intel/SGXDataCenterAttestationPrimitives/pull/123
>>
>> I tested and verified with Intel arch, the comparison indeed should be  
>> >.
>
> And this is a confirmed SDM bug, correct?

yes, the pseudo code for ECREATE is inaccurate and inconsistent with the  
CPUID spec. The latter is correct.
Haitao

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

[Jarkko Sakkinen]

On Tue, Sep 01, 2020 at 10:06:32PM -0500, Haitao Huang wrote:
> On Fri, 03 Jul 2020 22:31:10 -0500, Jarkko Sakkinen
> <jarkko.sakkinen@linux.intel.com> wrote:
> 
> > On Wed, Jul 01, 2020 at 08:59:02PM -0700, Sean Christopherson wrote:
> > > On Thu, Jun 18, 2020 at 01:08:33AM +0300, Jarkko Sakkinen wrote:
> > > > +static int sgx_validate_secs(const struct sgx_secs *secs,
> > > > +			     unsigned long ssaframesize)
> > > > +{
> > > > +	if (secs->size < (2 * PAGE_SIZE) || !is_power_of_2(secs->size))
> > > > +		return -EINVAL;
> > > > +
> > > > +	if (secs->base & (secs->size - 1))
> > > > +		return -EINVAL;
> > > > +
> > > > +	if (secs->miscselect & sgx_misc_reserved_mask ||
> > > > +	    secs->attributes & sgx_attributes_reserved_mask ||
> > > > +	    secs->xfrm & sgx_xfrm_reserved_mask)
> > > > +		return -EINVAL;
> > > > +
> > > > +	if (secs->attributes & SGX_ATTR_MODE64BIT) {
> > > > +		if (secs->size > sgx_encl_size_max_64)
> > > > +			return -EINVAL;
> > > > +	} else if (secs->size > sgx_encl_size_max_32)
> > > > +		return -EINVAL;
> > > 
> > > These should be >=, not >, the SDM uses one of those fancy ≥ ligatures.
> > > 
> > > Internal versions use more obvious pseudocode, e.g.:
> > > 
> > >     if ((DS:TMP_SECS.ATTRIBUTES.MODE64BIT = 1) AND
> > >         (DS:TMP_SECS.SIZE AND (~((1 << CPUID.18.0:EDX[15:8]) – 1)))
> > >     {
> > >         #GP(0);
> > 
> > Updated as:
> > 
> > static int sgx_validate_secs(const struct sgx_secs *secs)
> > {
> > 	u64 max_size = (secs->attributes & SGX_ATTR_MODE64BIT) ?
> > 		       sgx_encl_size_max_64 : sgx_encl_size_max_32;
> > 
> > 	if (secs->size < (2 * PAGE_SIZE) || !is_power_of_2(secs->size))
> > 		return -EINVAL;
> > 
> > 	if (secs->base & (secs->size - 1))
> > 		return -EINVAL;
> > 
> > 	if (secs->miscselect & sgx_misc_reserved_mask ||
> > 	    secs->attributes & sgx_attributes_reserved_mask ||
> > 	    secs->xfrm & sgx_xfrm_reserved_mask)
> > 		return -EINVAL;
> > 
> > 	if (secs->size >= max_size)
> > 		return -EINVAL;
> > 
> 
> This should be > not >=. Issue raised and fixed by Fábio Silva for ported
> patches for OOT SGX support:
> https://github.com/intel/SGXDataCenterAttestationPrimitives/pull/123
> 
> I tested and verified with Intel arch, the comparison indeed should be >.
> 
> Thanks
> Haitao

Thans a lot!

I added this changelog entry to the v37 log:

* Fixed off-by-one error in a size calculation:
  https://github.com/intel/SGXDataCenterAttestationPrimitives/commit/e44cc238becf584cc079aef40b557c6af9a03f38

Given the Boris' earlier feedback I xref every changelog
entry in v37 changelog. Then it is also less time consuming
to spot if something is missing.

/Jarkko

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

[Dave Hansen]

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.

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

[Jarkko Sakkinen]

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

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

[Borislav Petkov]

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

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

[Dave Hansen]

On 10/27/20 3:05 AM, Borislav Petkov wrote:
> 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.

I can't think of a *lot* of spots where we have sanity checks like this
for memory.  We have cgroups and the overcommit limits.  But, in
general, folks can allocate as much memory as they want until
allocations start to fail.

Should SGX be any different?

If we had a sanity check that said, "you can only allocate 1/2 of
enclave memory", wouldn't that just make somebody mad because they want
one big enclave?

Or, do you just want a sanity check to see if, up front, the user is
asking for more enclave memory than there is on the *whole* system?
That's also sane, but it doesn't take overcommit into account.  That's
why, for instance, we have vm.overcommit_ratio for normal memory.

BTW, I think we all agree that a cgroup controller for enclave memory is
going to be needed eventually.

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

[Borislav Petkov]

On Tue, Oct 27, 2020 at 08:20:00AM -0700, Dave Hansen wrote:
> I can't think of a *lot* of spots where we have sanity checks like this
> for memory.  We have cgroups and the overcommit limits.  But, in
> general, folks can allocate as much memory as they want until
> allocations start to fail.
>
> Should SGX be any different?
> 
> If we had a sanity check that said, "you can only allocate 1/2 of
> enclave memory", wouldn't that just make somebody mad because they want
> one big enclave?
>
> Or, do you just want a sanity check to see if, up front, the user is
> asking for more enclave memory than there is on the *whole* system?
> That's also sane, but it doesn't take overcommit into account.  That's
> why, for instance, we have vm.overcommit_ratio for normal memory.

Yeah, you're making sense and there's really no need for SGX to be any
different. Especially since users are already familiar the "policy" of
failing allocations when too much memory requested. :-)

> BTW, I think we all agree that a cgroup controller for enclave memory is
> going to be needed eventually.

Right.

Thx.

-- 
Regards/Gruss,
    Boris.

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