Hi All,
Intel's Trust Domain Extensions (TDX) protect guest VMs from malicious
hosts and some physical attacks. VM guest with TDX support is called
as a TDX Guest.
In TDX guest, the attestation process is used to verify the TDX guest
trustworthiness to other entities before provisioning secrets to the
guest. For example, a key server may request for attestation before
releasing the encryption keys to mount the encrypted rootfs or
secondary drive.
This patch set adds attestation support for the TDX guest. Details
about the TDX attestation process and the steps involved are explained
in Documentation/x86/tdx.rst (added by patch 2/3).
Following are the details of the patch set:
Patch 1/3 -> Preparatory patch for adding attestation support.
Patch 2/3 -> Adds user interface driver to support attestation.
Patch 3/3 -> Adds selftest support for TDREPORT feature.
Commit log history is maintained in the individual patches.
Current overall status of this series is, it has no pending issues
and can be considered for the upcoming merge cycle.
Kuppuswamy Sathyanarayanan (3):
x86/tdx: Add a wrapper to get TDREPORT0 from the TDX Module
virt: Add TDX guest driver
selftests: tdx: Test TDX attestation GetReport support
Documentation/virt/coco/tdx-guest.rst | 52 ++++++
Documentation/virt/index.rst | 1 +
Documentation/x86/tdx.rst | 43 +++++
arch/x86/coco/tdx/tdx.c | 40 +++++
arch/x86/include/asm/tdx.h | 2 +
drivers/virt/Kconfig | 2 +
drivers/virt/Makefile | 1 +
drivers/virt/coco/tdx-guest/Kconfig | 10 ++
drivers/virt/coco/tdx-guest/Makefile | 2 +
drivers/virt/coco/tdx-guest/tdx-guest.c | 102 ++++++++++++
include/uapi/linux/tdx-guest.h | 42 +++++
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/tdx/Makefile | 7 +
tools/testing/selftests/tdx/config | 1 +
tools/testing/selftests/tdx/tdx_guest_test.c | 163 +++++++++++++++++++
15 files changed, 469 insertions(+)
create mode 100644 Documentation/virt/coco/tdx-guest.rst
create mode 100644 drivers/virt/coco/tdx-guest/Kconfig
create mode 100644 drivers/virt/coco/tdx-guest/Makefile
create mode 100644 drivers/virt/coco/tdx-guest/tdx-guest.c
create mode 100644 include/uapi/linux/tdx-guest.h
create mode 100644 tools/testing/selftests/tdx/Makefile
create mode 100644 tools/testing/selftests/tdx/config
create mode 100644 tools/testing/selftests/tdx/tdx_guest_test.c
--
2.34.1
Attestation is used to verify the trustworthiness of a TDX guest.
During the guest bring-up, the Intel TDX module measures and records
the initial contents and configuration of the guest, and at runtime,
guest software uses runtime measurement registers (RMTRs) to measure
and record details related to kernel image, command line params, ACPI
tables, initrd, etc. At guest runtime, the attestation process is used
to attest to these measurements.
The first step in the TDX attestation process is to get the TDREPORT
data. It is a fixed size data structure generated by the TDX module
which includes the above mentioned measurements data, a MAC ID to
protect the integrity of the TDREPORT, and a 64-Byte of user specified
data passed during TDREPORT request which can uniquely identify the
TDREPORT.
Intel's TDX guest driver exposes TDX_CMD_GET_REPORT0 IOCTL interface to
enable guest userspace to get the TDREPORT subtype 0.
Add a kernel self test module to test this ABI and verify the validity
of the generated TDREPORT.
Reviewed-by: Tony Luck <[email protected]>
Reviewed-by: Mika Westerberg <[email protected]>
Acked-by: Kai Huang <[email protected]>
Acked-by: Wander Lairson Costa <[email protected]>
Acked-by: Kirill A. Shutemov <[email protected]>
Signed-off-by: Kuppuswamy Sathyanarayanan <[email protected]>
---
Changes since v17:
* Renamed TDX_CMD_GET_REPORT to TDX_CMD_GET_REPORT0.
Changes since v16:
* Modified the code to adapt to fixed size reportdata and tdeport
buffers in struct tdx_report_req.
Changes since v15:
* None
Changes since v14:
* Fixed format issue in struct comments.
* Rebased on top of v6.1-rc1
Changes since v13:
* Removed __packed from TDREPORT structs.
* Since the guest driver is moved to drivers/virt/coco, removed
tools/arch/x86/include header folder usage.
* Fixed struct comments to match kernel-doc format.
* Fixed commit log as per review comments.
* Fixed some format issues in the code.
Changes since v12:
* Changed #ifdef DEBUG usage with if (DEBUG).
* Initialized reserved entries values to zero.
Changes since v11:
* Renamed devname with TDX_GUEST_DEVNAME.
Changes since v10:
* Replaced TD/TD Guest usage with guest or TDX guest.
* Reworded the subject line.
Changes since v9:
* Copied arch/x86/include/uapi/asm/tdx.h to tools/arch/x86/include to
decouple header dependency between kernel source and tools dir.
* Fixed Makefile to adapt to above change.
* Fixed commit log and comments.
* Added __packed to hardware structs.
Changes since v8:
* Please refer to https://lore.kernel.org/all/ \
20220728034420.648314-1-sathyanarayanan.kuppuswamy@linux.intel.com/
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/tdx/Makefile | 7 +
tools/testing/selftests/tdx/config | 1 +
tools/testing/selftests/tdx/tdx_guest_test.c | 163 +++++++++++++++++++
4 files changed, 172 insertions(+)
create mode 100644 tools/testing/selftests/tdx/Makefile
create mode 100644 tools/testing/selftests/tdx/config
create mode 100644 tools/testing/selftests/tdx/tdx_guest_test.c
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 0464b2c6c1e4..f60e14d16bfd 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -73,6 +73,7 @@ TARGETS += sync
TARGETS += syscall_user_dispatch
TARGETS += sysctl
TARGETS += tc-testing
+TARGETS += tdx
TARGETS += timens
ifneq (1, $(quicktest))
TARGETS += timers
diff --git a/tools/testing/selftests/tdx/Makefile b/tools/testing/selftests/tdx/Makefile
new file mode 100644
index 000000000000..8dd43517cd55
--- /dev/null
+++ b/tools/testing/selftests/tdx/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+
+CFLAGS += -O3 -Wl,-no-as-needed -Wall -static
+
+TEST_GEN_PROGS := tdx_guest_test
+
+include ../lib.mk
diff --git a/tools/testing/selftests/tdx/config b/tools/testing/selftests/tdx/config
new file mode 100644
index 000000000000..aa1edc829ab6
--- /dev/null
+++ b/tools/testing/selftests/tdx/config
@@ -0,0 +1 @@
+CONFIG_TDX_GUEST_DRIVER=y
diff --git a/tools/testing/selftests/tdx/tdx_guest_test.c b/tools/testing/selftests/tdx/tdx_guest_test.c
new file mode 100644
index 000000000000..2a2afd856798
--- /dev/null
+++ b/tools/testing/selftests/tdx/tdx_guest_test.c
@@ -0,0 +1,163 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Test TDX guest features
+ *
+ * Copyright (C) 2022 Intel Corporation.
+ *
+ * Author: Kuppuswamy Sathyanarayanan <[email protected]>
+ */
+
+#include <sys/ioctl.h>
+
+#include <errno.h>
+#include <fcntl.h>
+
+#include "../kselftest_harness.h"
+#include "../../../../include/uapi/linux/tdx-guest.h"
+
+#define TDX_GUEST_DEVNAME "/dev/tdx_guest"
+#define HEX_DUMP_SIZE 8
+#define DEBUG 0
+
+/**
+ * struct tdreport_type - Type header of TDREPORT_STRUCT.
+ * @type: Type of the TDREPORT (0 - SGX, 81 - TDX, rest are reserved)
+ * @sub_type: Subtype of the TDREPORT (Default value is 0).
+ * @version: TDREPORT version (Default value is 0).
+ * @reserved: Added for future extension.
+ *
+ * More details can be found in TDX v1.0 module specification, sec
+ * titled "REPORTTYPE".
+ */
+struct tdreport_type {
+ __u8 type;
+ __u8 sub_type;
+ __u8 version;
+ __u8 reserved;
+};
+
+/**
+ * struct reportmac - TDX guest report data, MAC and TEE hashes.
+ * @type: TDREPORT type header.
+ * @reserved1: Reserved for future extension.
+ * @cpu_svn: CPU security version.
+ * @tee_tcb_info_hash: SHA384 hash of TEE TCB INFO.
+ * @tee_td_info_hash: SHA384 hash of TDINFO_STRUCT.
+ * @reportdata: User defined unique data passed in TDG.MR.REPORT request.
+ * @reserved2: Reserved for future extension.
+ * @mac: CPU MAC ID.
+ *
+ * It is MAC-protected and contains hashes of the remainder of the
+ * report structure along with user provided report data. More details can
+ * be found in TDX v1.0 Module specification, sec titled "REPORTMACSTRUCT"
+ */
+struct reportmac {
+ struct tdreport_type type;
+ __u8 reserved1[12];
+ __u8 cpu_svn[16];
+ __u8 tee_tcb_info_hash[48];
+ __u8 tee_td_info_hash[48];
+ __u8 reportdata[64];
+ __u8 reserved2[32];
+ __u8 mac[32];
+};
+
+/**
+ * struct td_info - TDX guest measurements and configuration.
+ * @attr: TDX Guest attributes (like debug, spet_disable, etc).
+ * @xfam: Extended features allowed mask.
+ * @mrtd: Build time measurement register.
+ * @mrconfigid: Software-defined ID for non-owner-defined configuration
+ * of the guest - e.g., run-time or OS configuration.
+ * @mrowner: Software-defined ID for the guest owner.
+ * @mrownerconfig: Software-defined ID for owner-defined configuration of
+ * the guest - e.g., specific to the workload.
+ * @rtmr: Run time measurement registers.
+ * @reserved: Added for future extension.
+ *
+ * It contains the measurements and initial configuration of the TDX guest
+ * that was locked at initialization and a set of measurement registers
+ * that are run-time extendable. More details can be found in TDX v1.0
+ * Module specification, sec titled "TDINFO_STRUCT".
+ */
+struct td_info {
+ __u8 attr[8];
+ __u64 xfam;
+ __u64 mrtd[6];
+ __u64 mrconfigid[6];
+ __u64 mrowner[6];
+ __u64 mrownerconfig[6];
+ __u64 rtmr[24];
+ __u64 reserved[14];
+};
+
+/*
+ * struct tdreport - Output of TDCALL[TDG.MR.REPORT].
+ * @reportmac: Mac protected header of size 256 bytes.
+ * @tee_tcb_info: Additional attestable elements in the TCB are not
+ * reflected in the reportmac.
+ * @reserved: Added for future extension.
+ * @tdinfo: Measurements and configuration data of size 512 bytes.
+ *
+ * More details can be found in TDX v1.0 Module specification, sec
+ * titled "TDREPORT_STRUCT".
+ */
+struct tdreport {
+ struct reportmac reportmac;
+ __u8 tee_tcb_info[239];
+ __u8 reserved[17];
+ struct td_info tdinfo;
+};
+
+static void print_array_hex(const char *title, const char *prefix_str,
+ const void *buf, int len)
+{
+ int i, j, line_len, rowsize = HEX_DUMP_SIZE;
+ const __u8 *ptr = buf;
+
+ printf("\t\t%s", title);
+
+ for (j = 0; j < len; j += rowsize) {
+ line_len = rowsize < (len - j) ? rowsize : (len - j);
+ printf("%s%.8x:", prefix_str, j);
+ for (i = 0; i < line_len; i++)
+ printf(" %.2x", ptr[j + i]);
+ printf("\n");
+ }
+
+ printf("\n");
+}
+
+TEST(verify_report)
+{
+ struct tdx_report_req req;
+ struct tdreport *tdreport;
+ int devfd, i;
+
+ devfd = open(TDX_GUEST_DEVNAME, O_RDWR | O_SYNC);
+ ASSERT_LT(0, devfd);
+
+ /* Generate sample report data */
+ for (i = 0; i < TDX_REPORTDATA_LEN; i++)
+ req.reportdata[i] = i;
+
+ /* Get TDREPORT */
+ ASSERT_EQ(0, ioctl(devfd, TDX_CMD_GET_REPORT0, &req));
+
+ if (DEBUG) {
+ print_array_hex("\n\t\tTDX report data\n", "",
+ req.reportdata, sizeof(req.reportdata));
+
+ print_array_hex("\n\t\tTDX tdreport data\n", "",
+ req.tdreport, sizeof(req.tdreport));
+ }
+
+ /* Make sure TDREPORT data includes the REPORTDATA passed */
+ tdreport = (struct tdreport *)req.tdreport;
+ ASSERT_EQ(0, memcmp(&tdreport->reportmac.reportdata[0],
+ req.reportdata, sizeof(req.reportdata)));
+
+ ASSERT_EQ(0, close(devfd));
+}
+
+TEST_HARNESS_MAIN
--
2.34.1
To support TDX attestation, the TDX guest driver exposes an IOCTL
interface to allow userspace to get the TDREPORT0 (a.k.a. TDREPORT
subtype 0) from the TDX module via TDG.MR.TDREPORT TDCALL.
In order to get the TDREPORT0 in the TDX guest driver, instead of using
a low level function like __tdx_module_call(), add a
tdx_mcall_get_report0() wrapper function to handle it.
This is a preparatory patch for adding attestation support.
Acked-by: Wander Lairson Costa <[email protected]>
Signed-off-by: Kuppuswamy Sathyanarayanan <[email protected]>
---
Changes since v17:
* Included subtype index to TDREPORT and modified the commit
logs and comments to align with it.
* Renamed tdx_mcall_get_report() to tdx_mcall_get_report0()
Changes since v16
* Added invalid operand error code support.
* Removed subtype param in tdx_mcall_get_report().
Changes since v15:
* None
Changes since v14:
* Instead of exporting __tdx_module_call(), added a new wrapper.
* Rebased on top of v6.1-rc1
arch/x86/coco/tdx/tdx.c | 40 ++++++++++++++++++++++++++++++++++++++
arch/x86/include/asm/tdx.h | 2 ++
2 files changed, 42 insertions(+)
diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
index 928dcf7a20d9..4121c5d296ee 100644
--- a/arch/x86/coco/tdx/tdx.c
+++ b/arch/x86/coco/tdx/tdx.c
@@ -5,6 +5,8 @@
#define pr_fmt(fmt) "tdx: " fmt
#include <linux/cpufeature.h>
+#include <linux/export.h>
+#include <linux/io.h>
#include <asm/coco.h>
#include <asm/tdx.h>
#include <asm/vmx.h>
@@ -15,6 +17,7 @@
/* TDX module Call Leaf IDs */
#define TDX_GET_INFO 1
#define TDX_GET_VEINFO 3
+#define TDX_GET_REPORT 4
#define TDX_ACCEPT_PAGE 6
/* TDX hypercall Leaf IDs */
@@ -34,6 +37,12 @@
#define VE_GET_PORT_NUM(e) ((e) >> 16)
#define VE_IS_IO_STRING(e) ((e) & BIT(4))
+/* TDX Module call error codes */
+#define TDCALL_RETURN_CODE(a) ((a) >> 32)
+#define TDCALL_INVALID_OPERAND 0xc0000100
+
+#define TDREPORT_SUBTYPE_0 0
+
/*
* Wrapper for standard use of __tdx_hypercall with no output aside from
* return code.
@@ -98,6 +107,37 @@ static inline void tdx_module_call(u64 fn, u64 rcx, u64 rdx, u64 r8, u64 r9,
panic("TDCALL %lld failed (Buggy TDX module!)\n", fn);
}
+/**
+ * tdx_mcall_get_report0() - Wrapper to get TDREPORT0 (a.k.a. TDREPORT
+ * subtype 0) using TDG.MR.REPORT TDCALL.
+ * @reportdata: Address of the input buffer which contains user-defined
+ * REPORTDATA to be included into TDREPORT.
+ * @tdreport: Address of the output buffer to store TDREPORT.
+ *
+ * Refer to section titled "TDG.MR.REPORT leaf" in the TDX Module
+ * v1.0 specification for more information on TDG.MR.REPORT TDCALL.
+ * It is used in the TDX guest driver module to get the TDREPORT0.
+ *
+ * Return 0 on success, -EINVAL for invalid operands, or -EIO on
+ * other TDCALL failures.
+ */
+int tdx_mcall_get_report0(u8 *reportdata, u8 *tdreport)
+{
+ u64 ret;
+
+ ret = __tdx_module_call(TDX_GET_REPORT, virt_to_phys(tdreport),
+ virt_to_phys(reportdata), TDREPORT_SUBTYPE_0,
+ 0, NULL);
+ if (ret) {
+ if (TDCALL_RETURN_CODE(ret) == TDCALL_INVALID_OPERAND)
+ return -EINVAL;
+ return -EIO;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(tdx_mcall_get_report0);
+
static u64 get_cc_mask(void)
{
struct tdx_module_output out;
diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index 020c81a7c729..28d889c9aa16 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -67,6 +67,8 @@ void tdx_safe_halt(void);
bool tdx_early_handle_ve(struct pt_regs *regs);
+int tdx_mcall_get_report0(u8 *reportdata, u8 *tdreport);
+
#else
static inline void tdx_early_init(void) { };
--
2.34.1
Sathya, this conflicts with some fixes Kirill made that got applied in
6.1-rc3. Can you double-check that the result looks right and tests OK,
please?
https://git.kernel.org/pub/scm/linux/kernel/git/daveh/devel.git/log/?h=tdxreport
On 11/17/22 11:07 AM, Dave Hansen wrote:
> Sathya, this conflicts with some fixes Kirill made that got applied in
> 6.1-rc3. Can you double-check that the result looks right and tests OK,
> please?
>
> https://git.kernel.org/pub/scm/linux/kernel/git/daveh/devel.git/log/?h=tdxreport
It looks fine. Tested it and it works fine.
--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer