diff mbox series

[v41,12/24] x86/sgx: Add SGX_IOC_ENCLAVE_CREATE

Message ID 20201112220135.165028-13-jarkko@kernel.org (mailing list archive)
State New, archived
Headers show
Series Intel SGX foundations | expand

Commit Message

Jarkko Sakkinen Nov. 12, 2020, 10:01 p.m. UTC 
Add an ioctl() that performs ECREATE function of ENCLS instruction, which
creates SGX Enclave Control Structure (SECS).

Although the SECS is an in-memory data structure, it is present in enclave
memory and is not directly accessible by software.

Tested-by: Jethro Beekman <jethro@fortanix.com> # v40
# Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
# Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
Changes from v39:
* Remove sgx_validate_secs() and ECREATE do the validation. If it fails,
  return -EIO.

 .../userspace-api/ioctl/ioctl-number.rst      |   1 +
 arch/x86/include/uapi/asm/sgx.h               |  25 ++++
 arch/x86/kernel/cpu/sgx/Makefile              |   1 +
 arch/x86/kernel/cpu/sgx/driver.c              |  12 ++
 arch/x86/kernel/cpu/sgx/driver.h              |   3 +
 arch/x86/kernel/cpu/sgx/encl.c                |   8 ++
 arch/x86/kernel/cpu/sgx/encl.h                |   7 +
 arch/x86/kernel/cpu/sgx/ioctl.c               | 123 ++++++++++++++++++
 8 files changed, 180 insertions(+)
 create mode 100644 arch/x86/include/uapi/asm/sgx.h
 create mode 100644 arch/x86/kernel/cpu/sgx/ioctl.c

Comments

Jarkko Sakkinen Nov. 17, 2020, 5:35 p.m. UTC | #1 
On Sun, Nov 15, 2020 at 12:40:44PM +0800, Hillf Danton wrote:
> On Fri, 13 Nov 2020 00:01:23 +0200 Jarkko Sakkinen wrote:
> > 
> > +long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
> > +{
> > +	struct sgx_encl *encl = filep->private_data;
> > +	int ret;
> > +
> > +	if (test_and_set_bit(SGX_ENCL_IOCTL, &encl->flags))
> > +		return -EBUSY;
> 
> Looks like encl->ioctl_mutex is needed to exlusively serialize
> concurrent ioctl threads and make encl->flags free of the duty.
> Plus it can cut the confusing EBUSY in userspace as it is not
> a critical path in any form.

The reason it is there was lock juggling with sgx_encl_grow() [*].

Andd since you never should use these ioctl's in parallel so why not
explicitly signal it to the user space?

[*] https://lore.kernel.org/linux-sgx/20190827001128.25066-4-sean.j.christopherson@intel.com/

/Jarkko
diff mbox series

Patch

diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
index 55a2d9b2ce33..a4c75a28c839 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                                          <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
diff --git a/arch/x86/include/uapi/asm/sgx.h b/arch/x86/include/uapi/asm/sgx.h
new file mode 100644
index 000000000000..f31bb17e27c3
--- /dev/null
+++ b/arch/x86/include/uapi/asm/sgx.h
@@ -0,0 +1,25 @@ 
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Copyright(c) 2016-20 Intel Corporation.
+ */
+#ifndef _UAPI_ASM_X86_SGX_H
+#define _UAPI_ASM_X86_SGX_H
+
+#include <linux/types.h>
+#include <linux/ioctl.h>
+
+#define SGX_MAGIC 0xA4
+
+#define SGX_IOC_ENCLAVE_CREATE \
+	_IOW(SGX_MAGIC, 0x00, struct sgx_enclave_create)
+
+/**
+ * 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;
+};
+
+#endif /* _UAPI_ASM_X86_SGX_H */
diff --git a/arch/x86/kernel/cpu/sgx/Makefile b/arch/x86/kernel/cpu/sgx/Makefile
index 3fc451120735..91d3dc784a29 100644
--- a/arch/x86/kernel/cpu/sgx/Makefile
+++ b/arch/x86/kernel/cpu/sgx/Makefile
@@ -1,4 +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
index 248213dea78e..9878b542c616 100644
--- a/arch/x86/kernel/cpu/sgx/driver.c
+++ b/arch/x86/kernel/cpu/sgx/driver.c
@@ -88,10 +88,22 @@  static unsigned long sgx_get_unmapped_area(struct file *file,
 	return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
 }
 
+#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 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,
 };
diff --git a/arch/x86/kernel/cpu/sgx/driver.h b/arch/x86/kernel/cpu/sgx/driver.h
index cda9c43b7543..a728e8e848bd 100644
--- a/arch/x86/kernel/cpu/sgx/driver.h
+++ b/arch/x86/kernel/cpu/sgx/driver.h
@@ -9,8 +9,11 @@ 
 #include <linux/rwsem.h>
 #include <linux/sched.h>
 #include <linux/workqueue.h>
+#include <uapi/asm/sgx.h>
 #include "sgx.h"
 
+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
index 848b17a3a028..e60c504f869f 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -46,6 +46,7 @@  static vm_fault_t sgx_vma_fault(struct vm_fault *vmf)
 	struct sgx_encl_page *entry;
 	unsigned long phys_addr;
 	struct sgx_encl *encl;
+	unsigned long pfn;
 	vm_fault_t ret;
 
 	encl = vma->vm_private_data;
@@ -61,6 +62,13 @@  static vm_fault_t sgx_vma_fault(struct vm_fault *vmf)
 
 	phys_addr = sgx_get_epc_phys_addr(entry->epc_page);
 
+	/* Check if another thread got here first to insert the PTE. */
+	if (!follow_pfn(vma, addr, &pfn)) {
+		mutex_unlock(&encl->lock);
+
+		return VM_FAULT_NOPAGE;
+	}
+
 	ret = vmf_insert_pfn(vma, addr, PFN_DOWN(phys_addr));
 	if (ret != VM_FAULT_NOPAGE) {
 		mutex_unlock(&encl->lock);
diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h
index b7e02eab5868..6ecb03c08edf 100644
--- a/arch/x86/kernel/cpu/sgx/encl.h
+++ b/arch/x86/kernel/cpu/sgx/encl.h
@@ -26,9 +26,16 @@  struct sgx_encl_page {
 	struct sgx_encl *encl;
 };
 
+enum sgx_encl_flags {
+	SGX_ENCL_IOCTL		= BIT(0),
+	SGX_ENCL_DEBUG		= BIT(1),
+	SGX_ENCL_CREATED	= BIT(2),
+};
+
 struct sgx_encl {
 	unsigned long base;
 	unsigned long size;
+	unsigned long flags;
 	unsigned int page_cnt;
 	unsigned int secs_child_cnt;
 	struct mutex lock;
diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
new file mode 100644
index 000000000000..1355490843d1
--- /dev/null
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -0,0 +1,123 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*  Copyright(c) 2016-20 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"
+
+static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs)
+{
+	struct sgx_epc_page *secs_epc;
+	struct sgx_pageinfo pginfo;
+	struct sgx_secinfo secinfo;
+	unsigned long encl_size;
+	long ret;
+
+	/* The extra page goes to SECS. */
+	encl_size = secs->size + PAGE_SIZE;
+
+	secs_epc = __sgx_alloc_epc_page();
+	if (IS_ERR(secs_epc))
+		return PTR_ERR(secs_epc);
+
+	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_virt_addr(secs_epc));
+	if (ret) {
+		ret = -EIO;
+		goto err_out;
+	}
+
+	if (secs->attributes & SGX_ATTR_DEBUG)
+		set_bit(SGX_ENCL_DEBUG, &encl->flags);
+
+	encl->secs.encl = encl;
+	encl->base = secs->base;
+	encl->size = secs->size;
+
+	/* Set only after completion, as encl->lock has not been taken. */
+	set_bit(SGX_ENCL_CREATED, &encl->flags);
+
+	return 0;
+
+err_out:
+	sgx_free_epc_page(encl->secs.epc_page);
+	encl->secs.epc_page = NULL;
+
+	return ret;
+}
+
+/**
+ * sgx_ioc_enclave_create() - handler for %SGX_IOC_ENCLAVE_CREATE
+ * @encl:	An enclave pointer.
+ * @arg:	The ioctl argument.
+ *
+ * Allocate kernel data structures for the enclave and invoke ECREATE.
+ *
+ * Return:
+ * - 0:		Success.
+ * - -EIO:	ECREATE failed.
+ * - -errno:	POSIX error.
+ */
+static long sgx_ioc_enclave_create(struct sgx_encl *encl, void __user *arg)
+{
+	struct sgx_enclave_create create_arg;
+	void *secs;
+	int ret;
+
+	if (test_bit(SGX_ENCL_CREATED, &encl->flags))
+		return -EINVAL;
+
+	if (copy_from_user(&create_arg, arg, sizeof(create_arg)))
+		return -EFAULT;
+
+	secs = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!secs)
+		return -ENOMEM;
+
+	if (copy_from_user(secs, (void __user *)create_arg.src, PAGE_SIZE))
+		ret = -EFAULT;
+	else
+		ret = sgx_encl_create(encl, secs);
+
+	kfree(secs);
+	return ret;
+}
+
+long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
+{
+	struct sgx_encl *encl = filep->private_data;
+	int ret;
+
+	if (test_and_set_bit(SGX_ENCL_IOCTL, &encl->flags))
+		return -EBUSY;
+
+	switch (cmd) {
+	case SGX_IOC_ENCLAVE_CREATE:
+		ret = sgx_ioc_enclave_create(encl, (void __user *)arg);
+		break;
+	default:
+		ret = -ENOIOCTLCMD;
+		break;
+	}
+
+	clear_bit(SGX_ENCL_IOCTL, &encl->flags);
+	return ret;
+}