x86/sgx: Move provisioning device creation out of SGX driver

And extract sgx_set_attribute() out of sgx_ioc_enclave_provision() and
export it as symbol for KVM to use.

The provisioning key is sensitive. The SGX driver only allows to create
an enclave which can access the provisioning key when the enclave
creator has permission to open /dev/sgx_provision. It should apply to
a VM as well, as the provisioning key is platform-specific, thus an
unrestricted VM can also potentially compromise the provisioning key.

Move the provisioning device creation out of sgx_drv_init() to
sgx_init() as a preparation for adding SGX virtualization support,
so that even if the SGX driver is not enabled due to flexible launch
control not being available, SGX virtualization can still be enabled,
and use it to restrict a VM's capability of being able to access the
provisioning key.

 [ bp: Massage commit message. ]

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Acked-by: Dave Hansen <dave.hansen@intel.com>
Link: https://lkml.kernel.org/r/0f4d044d621561f26d5f4ef73e8dc6cd18cc7e79.1616136308.git.kai.huang@intel.com

diff --git a/arch/x86/include/asm/sgx.h b/arch/x86/include/asm/sgx.h
index 954042e04102960392f44da43e2a1e5f52688314..a16e2c9154a31262582fdf8df955394de8fbb17c 100644 (file)
--- a/arch/x86/include/asm/sgx.h
+++ b/arch/x86/include/asm/sgx.h
@@ -372,4 +372,7 @@ int sgx_virt_einit(void __user *sigstruct, void __user *token,
                   void __user *secs, u64 *lepubkeyhash, int *trapnr);
 #endif
 
+int sgx_set_attribute(unsigned long *allowed_attributes,
+                     unsigned int attribute_fd);
+
 #endif /* _ASM_X86_SGX_H */

diff --git a/arch/x86/kernel/cpu/sgx/driver.c b/arch/x86/kernel/cpu/sgx/driver.c
index 8ce6d8371cfbf74eba9a4eba624220350d43f1c9..aa9b8b8688676fc66ebc6fdd605fe4467991af13 100644 (file)
--- a/arch/x86/kernel/cpu/sgx/driver.c
+++ b/arch/x86/kernel/cpu/sgx/driver.c
@@ -136,10 +136,6 @@ static const struct file_operations sgx_encl_fops = {
        .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 = "sgx_enclave",
@@ -147,13 +143,6 @@ static struct miscdevice sgx_dev_enclave = {
        .fops = &sgx_encl_fops,
 };
 
-static struct miscdevice sgx_dev_provision = {
-       .minor = MISC_DYNAMIC_MINOR,
-       .name = "sgx_provision",
-       .nodename = "sgx_provision",
-       .fops = &sgx_provision_fops,
-};
-
 int __init sgx_drv_init(void)
 {
        unsigned int eax, ebx, ecx, edx;
@@ -187,11 +176,5 @@ int __init sgx_drv_init(void)
        if (ret)
                return ret;
 
-       ret = misc_register(&sgx_dev_provision);
-       if (ret) {
-               misc_deregister(&sgx_dev_enclave);
-               return ret;
-       }
-
        return 0;
 }

diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index 7be9c064a64003e7886ee61d3d8e2fee4aaefac7..83df20e3e633353ca0b707cda6cae51cb6f09714 100644 (file)
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -2,6 +2,7 @@
 /*  Copyright(c) 2016-20 Intel Corporation. */
 
 #include <asm/mman.h>
+#include <asm/sgx.h>
 #include <linux/mman.h>
 #include <linux/delay.h>
 #include <linux/file.h>
@@ -666,24 +667,11 @@ out:
 static long sgx_ioc_enclave_provision(struct sgx_encl *encl, void __user *arg)
 {
        struct sgx_enclave_provision params;
-       struct file *file;
 
        if (copy_from_user(&params, arg, sizeof(params)))
                return -EFAULT;
 
-       file = fget(params.fd);
-       if (!file)
-               return -EINVAL;
-
-       if (file->f_op != &sgx_provision_fops) {
-               fput(file);
-               return -EINVAL;
-       }
-
-       encl->attributes_mask |= SGX_ATTR_PROVISIONKEY;
-
-       fput(file);
-       return 0;
+       return sgx_set_attribute(&encl->attributes_mask, params.fd);
 }
 
 long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 227f1e2ad9cf99d541e8deb9bf8924a0a716fc93..92cb11dffd4cbaab9326a5c23f3903b7253f651b 100644 (file)
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -1,14 +1,17 @@
 // SPDX-License-Identifier: GPL-2.0
 /*  Copyright(c) 2016-20 Intel Corporation. */
 
+#include <linux/file.h>
 #include <linux/freezer.h>
 #include <linux/highmem.h>
 #include <linux/kthread.h>
+#include <linux/miscdevice.h>
 #include <linux/pagemap.h>
 #include <linux/ratelimit.h>
 #include <linux/sched/mm.h>
 #include <linux/sched/signal.h>
 #include <linux/slab.h>
+#include <asm/sgx.h>
 #include "driver.h"
 #include "encl.h"
 #include "encls.h"
@@ -743,6 +746,51 @@ void sgx_update_lepubkeyhash(u64 *lepubkeyhash)
                wrmsrl(MSR_IA32_SGXLEPUBKEYHASH0 + i, lepubkeyhash[i]);
 }
 
+const struct file_operations sgx_provision_fops = {
+       .owner                  = THIS_MODULE,
+};
+
+static struct miscdevice sgx_dev_provision = {
+       .minor = MISC_DYNAMIC_MINOR,
+       .name = "sgx_provision",
+       .nodename = "sgx_provision",
+       .fops = &sgx_provision_fops,
+};
+
+/**
+ * sgx_set_attribute() - Update allowed attributes given file descriptor
+ * @allowed_attributes:                Pointer to allowed enclave attributes
+ * @attribute_fd:              File descriptor for specific attribute
+ *
+ * Append enclave attribute indicated by file descriptor to allowed
+ * attributes. Currently only SGX_ATTR_PROVISIONKEY indicated by
+ * /dev/sgx_provision is supported.
+ *
+ * Return:
+ * -0:         SGX_ATTR_PROVISIONKEY is appended to allowed_attributes
+ * -EINVAL:    Invalid, or not supported file descriptor
+ */
+int sgx_set_attribute(unsigned long *allowed_attributes,
+                     unsigned int attribute_fd)
+{
+       struct file *file;
+
+       file = fget(attribute_fd);
+       if (!file)
+               return -EINVAL;
+
+       if (file->f_op != &sgx_provision_fops) {
+               fput(file);
+               return -EINVAL;
+       }
+
+       *allowed_attributes |= SGX_ATTR_PROVISIONKEY;
+
+       fput(file);
+       return 0;
+}
+EXPORT_SYMBOL_GPL(sgx_set_attribute);
+
 static int __init sgx_init(void)
 {
        int ret;
@@ -759,6 +807,10 @@ static int __init sgx_init(void)
                goto err_page_cache;
        }
 
+       ret = misc_register(&sgx_dev_provision);
+       if (ret)
+               goto err_kthread;
+
        /*
         * Always try to initialize the native *and* KVM drivers.
         * The KVM driver is less picky than the native one and
@@ -770,10 +822,13 @@ static int __init sgx_init(void)
        ret = sgx_drv_init();
 
        if (sgx_vepc_init() && ret)
-               goto err_kthread;
+               goto err_provision;
 
        return 0;
 
+err_provision:
+       misc_deregister(&sgx_dev_provision);
+
 err_kthread:
        kthread_stop(ksgxd_tsk);