From 4d2a7bfad5b79b3a362fc7cfed8d7ddbd263a838 Mon Sep 17 00:00:00 2001 From: Cedric Xing Date: Wed, 7 May 2025 18:06:06 -0700 Subject: [PATCH] virt: tdx-guest: Expose TDX MRs as sysfs attributes MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Expose the most commonly used TDX MRs (Measurement Registers) as sysfs attributes. Use the ioctl() interface of /dev/tdx_guest to request a full TDREPORT for access to other TD measurements. Directory structure of TDX MRs inside a TDVM is as follows: /sys/class/misc/tdx_guest └── measurements ├── mrconfigid ├── mrowner ├── mrownerconfig ├── mrtd:sha384 ├── rtmr0:sha384 ├── rtmr1:sha384 ├── rtmr2:sha384 └── rtmr3:sha384 Read the file/attribute to retrieve the current value of an MR. Write to the file/attribute (if writable) to extend the corresponding RTMR. Refer to Documentation/ABI/testing/sysfs-devices-virtual-misc-tdx_guest for more information. Signed-off-by: Cedric Xing Acked-by: Dionna Amalie Glaze [djbw: fixup exit order] Link: https://patch.msgid.link/20250508010606.4129953-1-dan.j.williams@intel.com Signed-off-by: Dan Williams --- .../sysfs-devices-virtual-misc-tdx_guest | 63 ++++++++ MAINTAINERS | 1 + drivers/virt/coco/tdx-guest/Kconfig | 1 + drivers/virt/coco/tdx-guest/tdx-guest.c | 151 +++++++++++++++++- 4 files changed, 214 insertions(+), 2 deletions(-) create mode 100644 Documentation/ABI/testing/sysfs-devices-virtual-misc-tdx_guest diff --git a/Documentation/ABI/testing/sysfs-devices-virtual-misc-tdx_guest b/Documentation/ABI/testing/sysfs-devices-virtual-misc-tdx_guest new file mode 100644 index 0000000000000..8fca56c8c9dfe --- /dev/null +++ b/Documentation/ABI/testing/sysfs-devices-virtual-misc-tdx_guest @@ -0,0 +1,63 @@ +What: /sys/devices/virtual/misc/tdx_guest/measurements/MRNAME[:HASH] +Date: April, 2025 +KernelVersion: v6.16 +Contact: linux-coco@lists.linux.dev +Description: + Value of a TDX measurement register (MR). MRNAME and HASH above + are placeholders. The optional suffix :HASH is used for MRs + that have associated hash algorithms. See below for a complete + list of TDX MRs exposed via sysfs. Refer to Intel TDX Module + ABI Specification for the definition of TDREPORT and the full + list of TDX measurements. + + Intel TDX Module ABI Specification can be found at: + https://www.intel.com/content/www/us/en/developer/tools/trust-domain-extensions/documentation.html#architecture + + See also: + https://docs.kernel.org/driver-api/coco/measurement-registers.html + +What: /sys/devices/virtual/misc/tdx_guest/measurements/mrconfigid +Date: April, 2025 +KernelVersion: v6.16 +Contact: linux-coco@lists.linux.dev +Description: + (RO) MRCONFIGID - 48-byte immutable storage typically used for + software-defined ID for non-owner-defined configuration of the + guest TD – e.g., run-time or OS configuration. + +What: /sys/devices/virtual/misc/tdx_guest/measurements/mrowner +Date: April, 2025 +KernelVersion: v6.16 +Contact: linux-coco@lists.linux.dev +Description: + (RO) MROWNER - 48-byte immutable storage typically used for + software-defined ID for the guest TD’s owner. + +What: /sys/devices/virtual/misc/tdx_guest/measurements/mrownerconfig +Date: April, 2025 +KernelVersion: v6.16 +Contact: linux-coco@lists.linux.dev +Description: + (RO) MROWNERCONFIG - 48-byte immutable storage typically used + for software-defined ID for owner-defined configuration of the + guest TD – e.g., specific to the workload rather than the + run-time or OS. + +What: /sys/devices/virtual/misc/tdx_guest/measurements/mrtd:sha384 +Date: April, 2025 +KernelVersion: v6.16 +Contact: linux-coco@lists.linux.dev +Description: + (RO) MRTD - Measurement of the initial contents of the TD. + +What: /sys/devices/virtual/misc/tdx_guest/measurements/rtmr[0123]:sha384 +Date: April, 2025 +KernelVersion: v6.16 +Contact: linux-coco@lists.linux.dev +Description: + (RW) RTMR[0123] - 4 Run-Time extendable Measurement Registers. + Read from any of these returns the current value of the + corresponding RTMR. Write extends the written buffer to the + RTMR. All writes must start at offset 0 and be 48 bytes in + size. Partial writes will result in EINVAL returned by the + write() syscall. diff --git a/MAINTAINERS b/MAINTAINERS index 8bf8a818bce52..912e16ace0b4a 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -26321,6 +26321,7 @@ L: x86@kernel.org L: linux-coco@lists.linux.dev S: Supported T: git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/tdx +F: Documentation/ABI/testing/sysfs-devices-virtual-misc-tdx_guest F: arch/x86/boot/compressed/tdx* F: arch/x86/coco/tdx/ F: arch/x86/include/asm/shared/tdx.h diff --git a/drivers/virt/coco/tdx-guest/Kconfig b/drivers/virt/coco/tdx-guest/Kconfig index 22dd59e194315..dbbdc14383b13 100644 --- a/drivers/virt/coco/tdx-guest/Kconfig +++ b/drivers/virt/coco/tdx-guest/Kconfig @@ -2,6 +2,7 @@ config TDX_GUEST_DRIVER tristate "TDX Guest driver" depends on INTEL_TDX_GUEST select TSM_REPORTS + select TSM_MEASUREMENTS help The driver provides userspace interface to communicate with the TDX module to request the TDX guest details like attestation diff --git a/drivers/virt/coco/tdx-guest/tdx-guest.c b/drivers/virt/coco/tdx-guest/tdx-guest.c index 224e7dde9cdee..15810fb02d984 100644 --- a/drivers/virt/coco/tdx-guest/tdx-guest.c +++ b/drivers/virt/coco/tdx-guest/tdx-guest.c @@ -5,6 +5,8 @@ * Copyright (C) 2022 Intel Corporation */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + #include #include #include @@ -15,14 +17,146 @@ #include #include #include +#include #include -#include +#include #include #include #include +/* TDREPORT buffer */ +static u8 *tdx_report_buf; + +/* Lock to serialize TDG.MR.REPORT and TDG.MR.RTMR.EXTEND TDCALLs */ +static DEFINE_MUTEX(mr_lock); + +/* TDREPORT fields */ +enum { + TDREPORT_reportdata = 128, + TDREPORT_tee_tcb_info = 256, + TDREPORT_tdinfo = TDREPORT_tee_tcb_info + 256, + TDREPORT_attributes = TDREPORT_tdinfo, + TDREPORT_xfam = TDREPORT_attributes + sizeof(u64), + TDREPORT_mrtd = TDREPORT_xfam + sizeof(u64), + TDREPORT_mrconfigid = TDREPORT_mrtd + SHA384_DIGEST_SIZE, + TDREPORT_mrowner = TDREPORT_mrconfigid + SHA384_DIGEST_SIZE, + TDREPORT_mrownerconfig = TDREPORT_mrowner + SHA384_DIGEST_SIZE, + TDREPORT_rtmr0 = TDREPORT_mrownerconfig + SHA384_DIGEST_SIZE, + TDREPORT_rtmr1 = TDREPORT_rtmr0 + SHA384_DIGEST_SIZE, + TDREPORT_rtmr2 = TDREPORT_rtmr1 + SHA384_DIGEST_SIZE, + TDREPORT_rtmr3 = TDREPORT_rtmr2 + SHA384_DIGEST_SIZE, + TDREPORT_servtd_hash = TDREPORT_rtmr3 + SHA384_DIGEST_SIZE, +}; + +static int tdx_do_report(sockptr_t data, sockptr_t tdreport) +{ + scoped_cond_guard(mutex_intr, return -EINTR, &mr_lock) { + u8 *reportdata = tdx_report_buf + TDREPORT_reportdata; + int ret; + + if (!sockptr_is_null(data) && + copy_from_sockptr(reportdata, data, TDX_REPORTDATA_LEN)) + return -EFAULT; + + ret = tdx_mcall_get_report0(reportdata, tdx_report_buf); + if (WARN_ONCE(ret, "tdx_mcall_get_report0() failed: %d", ret)) + return ret; + + if (!sockptr_is_null(tdreport) && + copy_to_sockptr(tdreport, tdx_report_buf, TDX_REPORT_LEN)) + return -EFAULT; + } + return 0; +} + +static int tdx_do_extend(u8 mr_ind, const u8 *data) +{ + scoped_cond_guard(mutex_intr, return -EINTR, &mr_lock) { + /* + * TDX requires @extend_buf to be 64-byte aligned. + * It's safe to use REPORTDATA buffer for that purpose because + * tdx_mr_report/extend_lock() are mutually exclusive. + */ + u8 *extend_buf = tdx_report_buf + TDREPORT_reportdata; + int ret; + + memcpy(extend_buf, data, SHA384_DIGEST_SIZE); + + ret = tdx_mcall_extend_rtmr(mr_ind, extend_buf); + if (WARN_ONCE(ret, "tdx_mcall_extend_rtmr(%u) failed: %d", mr_ind, ret)) + return ret; + } + return 0; +} + +#define TDX_MR_(r) .mr_value = (void *)TDREPORT_##r, TSM_MR_(r, SHA384) +static struct tsm_measurement_register tdx_mrs[] = { + { TDX_MR_(rtmr0) | TSM_MR_F_RTMR }, + { TDX_MR_(rtmr1) | TSM_MR_F_RTMR }, + { TDX_MR_(rtmr2) | TSM_MR_F_RTMR }, + { TDX_MR_(rtmr3) | TSM_MR_F_RTMR }, + { TDX_MR_(mrtd) }, + { TDX_MR_(mrconfigid) | TSM_MR_F_NOHASH }, + { TDX_MR_(mrowner) | TSM_MR_F_NOHASH }, + { TDX_MR_(mrownerconfig) | TSM_MR_F_NOHASH }, +}; +#undef TDX_MR_ + +static int tdx_mr_refresh(const struct tsm_measurements *tm) +{ + return tdx_do_report(KERNEL_SOCKPTR(NULL), KERNEL_SOCKPTR(NULL)); +} + +static int tdx_mr_extend(const struct tsm_measurements *tm, + const struct tsm_measurement_register *mr, + const u8 *data) +{ + return tdx_do_extend(mr - tm->mrs, data); +} + +static struct tsm_measurements tdx_measurements = { + .mrs = tdx_mrs, + .nr_mrs = ARRAY_SIZE(tdx_mrs), + .refresh = tdx_mr_refresh, + .write = tdx_mr_extend, +}; + +static const struct attribute_group *tdx_mr_init(void) +{ + const struct attribute_group *g; + int rc; + + u8 *buf __free(kfree) = kzalloc(TDX_REPORT_LEN, GFP_KERNEL); + if (!buf) + return ERR_PTR(-ENOMEM); + + tdx_report_buf = buf; + rc = tdx_mr_refresh(&tdx_measurements); + if (rc) + return ERR_PTR(rc); + + /* + * @mr_value was initialized with the offset only, while the base + * address is being added here. + */ + for (size_t i = 0; i < ARRAY_SIZE(tdx_mrs); ++i) + *(long *)&tdx_mrs[i].mr_value += (long)buf; + + g = tsm_mr_create_attribute_group(&tdx_measurements); + if (!IS_ERR(g)) + tdx_report_buf = no_free_ptr(buf); + + return g; +} + +static void tdx_mr_deinit(const struct attribute_group *mr_grp) +{ + tsm_mr_free_attribute_group(mr_grp); + kfree(tdx_report_buf); +} + /* * Intel's SGX QE implementation generally uses Quote size less * than 8K (2K Quote data + ~5K of certificate blob). @@ -285,10 +419,16 @@ static const struct file_operations tdx_guest_fops = { .unlocked_ioctl = tdx_guest_ioctl, }; +static const struct attribute_group *tdx_attr_groups[] = { + NULL, /* measurements */ + NULL +}; + static struct miscdevice tdx_misc_dev = { .name = KBUILD_MODNAME, .minor = MISC_DYNAMIC_MINOR, .fops = &tdx_guest_fops, + .groups = tdx_attr_groups, }; static const struct x86_cpu_id tdx_guest_ids[] = { @@ -311,9 +451,13 @@ static int __init tdx_guest_init(void) if (!x86_match_cpu(tdx_guest_ids)) return -ENODEV; + tdx_attr_groups[0] = tdx_mr_init(); + if (IS_ERR(tdx_attr_groups[0])) + return PTR_ERR(tdx_attr_groups[0]); + ret = misc_register(&tdx_misc_dev); if (ret) - return ret; + goto deinit_mr; quote_data = alloc_quote_buf(); if (!quote_data) { @@ -332,6 +476,8 @@ free_quote: free_quote_buf(quote_data); free_misc: misc_deregister(&tdx_misc_dev); +deinit_mr: + tdx_mr_deinit(tdx_attr_groups[0]); return ret; } @@ -342,6 +488,7 @@ static void __exit tdx_guest_exit(void) tsm_unregister(&tdx_tsm_ops); free_quote_buf(quote_data); misc_deregister(&tdx_misc_dev); + tdx_mr_deinit(tdx_attr_groups[0]); } module_exit(tdx_guest_exit); -- 2.47.2