[PATCH v6 08/14] x86: Secure Launch kernel late boot stub
Jarkko Sakkinen
jarkko at kernel.org
Wed May 10 16:02:34 PDT 2023
On Thu May 4, 2023 at 5:50 PM EEST, Ross Philipson wrote:
> The routine slaunch_setup is called out of the x86 specific setup_arch
> routine during early kernel boot. After determining what platform is
> present, various operations specific to that platform occur. This
> includes finalizing setting for the platform late launch and verifying
> that memory protections are in place.
>
> For TXT, this code also reserves the original compressed kernel setup
> area where the APs were left looping so that this memory cannot be used.
>
> Signed-off-by: Ross Philipson <ross.philipson at oracle.com>
> ---
> arch/x86/kernel/Makefile | 1 +
> arch/x86/kernel/setup.c | 3 +
> arch/x86/kernel/slaunch.c | 497 +++++++++++++++++++++++++++++++++++++++++++++
> drivers/iommu/intel/dmar.c | 4 +
> 4 files changed, 505 insertions(+)
> create mode 100644 arch/x86/kernel/slaunch.c
>
> diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
> index dd61752..3d2a33e 100644
> --- a/arch/x86/kernel/Makefile
> +++ b/arch/x86/kernel/Makefile
> @@ -72,6 +72,7 @@ obj-$(CONFIG_X86_32) += tls.o
> obj-$(CONFIG_IA32_EMULATION) += tls.o
> obj-y += step.o
> obj-$(CONFIG_INTEL_TXT) += tboot.o
> +obj-$(CONFIG_SECURE_LAUNCH) += slaunch.o
> obj-$(CONFIG_ISA_DMA_API) += i8237.o
> obj-y += stacktrace.o
> obj-y += cpu/
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 16babff..592c09e 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -21,6 +21,7 @@
> #include <linux/root_dev.h>
> #include <linux/hugetlb.h>
> #include <linux/tboot.h>
> +#include <linux/slaunch.h>
Only because of pure curiosity: what made you choose this location in
the middle for the new include? :-)
> #include <linux/usb/xhci-dbgp.h>
> #include <linux/static_call.h>
> #include <linux/swiotlb.h>
> @@ -1063,6 +1064,8 @@ void __init setup_arch(char **cmdline_p)
> early_gart_iommu_check();
> #endif
>
> + slaunch_setup_txt();
> +
> /*
> * partially used pages are not usable - thus
> * we are rounding upwards:
> diff --git a/arch/x86/kernel/slaunch.c b/arch/x86/kernel/slaunch.c
> new file mode 100644
> index 0000000..7dba088
> --- /dev/null
> +++ b/arch/x86/kernel/slaunch.c
> @@ -0,0 +1,497 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Secure Launch late validation/setup and finalization support.
> + *
> + * Copyright (c) 2022, Oracle and/or its affiliates.
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/linkage.h>
> +#include <linux/mm.h>
> +#include <linux/io.h>
> +#include <linux/uaccess.h>
> +#include <linux/security.h>
> +#include <linux/memblock.h>
> +#include <asm/segment.h>
> +#include <asm/sections.h>
> +#include <asm/tlbflush.h>
> +#include <asm/e820/api.h>
> +#include <asm/setup.h>
> +#include <linux/slr_table.h>
> +#include <linux/slaunch.h>
> +
> +static u32 sl_flags;
> +static struct sl_ap_wake_info ap_wake_info;
> +static u64 evtlog_addr;
> +static u32 evtlog_size;
> +static u64 vtd_pmr_lo_size;
> +
> +/* This should be plenty of room */
> +static u8 txt_dmar[PAGE_SIZE] __aligned(16);
> +
> +u32 slaunch_get_flags(void)
> +{
> + return sl_flags;
> +}
> +EXPORT_SYMBOL(slaunch_get_flags);
> +
> +struct sl_ap_wake_info *slaunch_get_ap_wake_info(void)
> +{
> + return &ap_wake_info;
> +}
> +
> +struct acpi_table_header *slaunch_get_dmar_table(struct acpi_table_header *dmar)
> +{
> + /* The DMAR is only stashed and provided via TXT on Intel systems */
> + if (memcmp(txt_dmar, "DMAR", 4))
> + return dmar;
> +
> + return (struct acpi_table_header *)(&txt_dmar[0]);
> +}
> +
> +void __noreturn slaunch_txt_reset(void __iomem *txt,
> + const char *msg, u64 error)
> +{
> + u64 one = 1, val;
> +
> + pr_err("%s", msg);
> +
> + /*
> + * This performs a TXT reset with a sticky error code. The reads of
> + * TXT_CR_E2STS act as barriers.
> + */
> + memcpy_toio(txt + TXT_CR_ERRORCODE, &error, sizeof(error));
> + memcpy_fromio(&val, txt + TXT_CR_E2STS, sizeof(val));
> + memcpy_toio(txt + TXT_CR_CMD_NO_SECRETS, &one, sizeof(one));
> + memcpy_fromio(&val, txt + TXT_CR_E2STS, sizeof(val));
> + memcpy_toio(txt + TXT_CR_CMD_UNLOCK_MEM_CONFIG, &one, sizeof(one));
> + memcpy_fromio(&val, txt + TXT_CR_E2STS, sizeof(val));
> + memcpy_toio(txt + TXT_CR_CMD_RESET, &one, sizeof(one));
> +
> + for ( ; ; )
> + asm volatile ("hlt");
> +
> + unreachable();
> +}
> +
> +/*
> + * The TXT heap is too big to map all at once with early_ioremap
> + * so it is done a table at a time.
> + */
> +static void __init *txt_early_get_heap_table(void __iomem *txt, u32 type,
> + u32 bytes)
> +{
> + u64 base, size, offset = 0;
> + void *heap;
> + int i;
> +
> + if (type > TXT_SINIT_TABLE_MAX)
> + slaunch_txt_reset(txt,
> + "Error invalid table type for early heap walk\n",
> + SL_ERROR_HEAP_WALK);
Align with 'txt'.
> +
> + memcpy_fromio(&base, txt + TXT_CR_HEAP_BASE, sizeof(base));
> + memcpy_fromio(&size, txt + TXT_CR_HEAP_SIZE, sizeof(size));
> +
> + /* Iterate over heap tables looking for table of "type" */
> + for (i = 0; i < type; i++) {
> + base += offset;
> + heap = early_memremap(base, sizeof(u64));
> + if (!heap)
> + slaunch_txt_reset(txt,
> + "Error early_memremap of heap for heap walk\n",
> + SL_ERROR_HEAP_MAP);
> +
> + offset = *((u64 *)heap);
> +
> + /*
> + * After the first iteration, any offset of zero is invalid and
> + * implies the TXT heap is corrupted.
> + */
> + if (!offset)
> + slaunch_txt_reset(txt,
> + "Error invalid 0 offset in heap walk\n",
> + SL_ERROR_HEAP_ZERO_OFFSET);
> +
> + early_memunmap(heap, sizeof(u64));
> + }
> +
> + /* Skip the size field at the head of each table */
> + base += sizeof(u64);
> + heap = early_memremap(base, bytes);
> + if (!heap)
> + slaunch_txt_reset(txt,
> + "Error early_memremap of heap section\n",
> + SL_ERROR_HEAP_MAP);
> +
> + return heap;
> +}
> +
> +static void __init txt_early_put_heap_table(void *addr, unsigned long size)
> +{
> + early_memunmap(addr, size);
> +}
> +
> +/*
> + * TXT uses a special set of VTd registers to protect all of memory from DMA
> + * until the IOMMU can be programmed to protect memory. There is the low
> + * memory PMR that can protect all memory up to 4G. The high memory PRM can
> + * be setup to protect all memory beyond 4Gb. Validate that these values cover
> + * what is expected.
> + */
> +static void __init slaunch_verify_pmrs(void __iomem *txt)
> +{
> + struct txt_os_sinit_data *os_sinit_data;
> + u32 field_offset, err = 0;
> + const char *errmsg = "";
> + unsigned long last_pfn;
> +
> + field_offset = offsetof(struct txt_os_sinit_data, lcp_po_base);
> + os_sinit_data = txt_early_get_heap_table(txt, TXT_OS_SINIT_DATA_TABLE,
> + field_offset);
> +
> + /* Save a copy */
> + vtd_pmr_lo_size = os_sinit_data->vtd_pmr_lo_size;
> +
> + last_pfn = e820__end_of_ram_pfn();
> +
> + /*
> + * First make sure the hi PMR covers all memory above 4G. In the
> + * unlikely case where there is < 4G on the system, the hi PMR will
> + * not be set.
> + */
> + if (os_sinit_data->vtd_pmr_hi_base != 0x0ULL) {
> + if (os_sinit_data->vtd_pmr_hi_base != 0x100000000ULL) {
> + err = SL_ERROR_HI_PMR_BASE;
> + errmsg = "Error hi PMR base\n";
> + goto out;
> + }
> +
> + if (PFN_PHYS(last_pfn) > os_sinit_data->vtd_pmr_hi_base +
> + os_sinit_data->vtd_pmr_hi_size) {
> + err = SL_ERROR_HI_PMR_SIZE;
> + errmsg = "Error hi PMR size\n";
> + goto out;
> + }
> + }
> +
> + /*
> + * Lo PMR base should always be 0. This was already checked in
> + * early stub.
> + */
> +
> + /*
> + * Check that if the kernel was loaded below 4G, that it is protected
> + * by the lo PMR. Note this is the decompressed kernel. The ACM would
> + * have ensured the compressed kernel (the MLE image) was protected.
> + */
> + if ((__pa_symbol(_end) < 0x100000000ULL) &&
> + (__pa_symbol(_end) > os_sinit_data->vtd_pmr_lo_size)) {
> + err = SL_ERROR_LO_PMR_MLE;
> + errmsg = "Error lo PMR does not cover MLE kernel\n";
> + }
> +
> + /*
> + * Other regions of interest like boot param, AP wake block, cmdline
> + * already checked for PMR coverage in the early stub code.
> + */
> +
> +out:
> + txt_early_put_heap_table(os_sinit_data, field_offset);
> +
> + if (err)
> + slaunch_txt_reset(txt, errmsg, err);
> +}
> +
> +static void __init slaunch_txt_reserve_range(u64 base, u64 size)
> +{
> + int type;
> +
> + type = e820__get_entry_type(base, base + size - 1);
> + if (type == E820_TYPE_RAM) {
> + pr_info("memblock reserve base: %llx size: %llx\n", base, size);
> + memblock_reserve(base, size);
> + }
> +}
> +
> +/*
> + * For Intel, certain regions of memory must be marked as reserved by putting
> + * them on the memblock reserved list if they are not already e820 reserved.
> + * This includes:
> + * - The TXT HEAP
> + * - The ACM area
> + * - The TXT private register bank
> + * - The MDR list sent to the MLE by the ACM (see TXT specification)
> + * (Normally the above are properly reserved by firmware but if it was not
> + * done, reserve them now)
> + * - The AP wake block
> + * - TPM log external to the TXT heap
> + *
> + * Also if the low PMR doesn't cover all memory < 4G, any RAM regions above
> + * the low PMR must be reservered too.
> + */
> +static void __init slaunch_txt_reserve(void __iomem *txt)
> +{
> + struct txt_sinit_memory_descriptor_record *mdr;
> + struct txt_sinit_mle_data *sinit_mle_data;
> + u64 base, size, heap_base, heap_size;
> + u32 mdrnum, mdroffset, mdrslen;
> + u32 field_offset, i;
> + void *mdrs;
> +
> + base = TXT_PRIV_CONFIG_REGS_BASE;
> + size = TXT_PUB_CONFIG_REGS_BASE - TXT_PRIV_CONFIG_REGS_BASE;
> + slaunch_txt_reserve_range(base, size);
> +
> + memcpy_fromio(&heap_base, txt + TXT_CR_HEAP_BASE, sizeof(heap_base));
> + memcpy_fromio(&heap_size, txt + TXT_CR_HEAP_SIZE, sizeof(heap_size));
> + slaunch_txt_reserve_range(heap_base, heap_size);
> +
> + memcpy_fromio(&base, txt + TXT_CR_SINIT_BASE, sizeof(base));
> + memcpy_fromio(&size, txt + TXT_CR_SINIT_SIZE, sizeof(size));
> + slaunch_txt_reserve_range(base, size);
> +
> + field_offset = offsetof(struct txt_sinit_mle_data,
> + sinit_vtd_dmar_table_size);
> + sinit_mle_data = txt_early_get_heap_table(txt, TXT_SINIT_MLE_DATA_TABLE,
> + field_offset);
> +
> + mdrnum = sinit_mle_data->num_of_sinit_mdrs;
> + mdroffset = sinit_mle_data->sinit_mdrs_table_offset;
> +
> + txt_early_put_heap_table(sinit_mle_data, field_offset);
> +
> + if (!mdrnum)
> + goto nomdr;
> +
> + mdrslen = mdrnum * sizeof(struct txt_sinit_memory_descriptor_record);
> +
> + mdrs = txt_early_get_heap_table(txt, TXT_SINIT_MLE_DATA_TABLE,
> + mdroffset + mdrslen - 8);
> +
> + mdr = mdrs + mdroffset - 8;
> +
> + for (i = 0; i < mdrnum; i++, mdr++) {
> + /* Spec says some entries can have length 0, ignore them */
> + if (mdr->type > 0 && mdr->length > 0)
> + slaunch_txt_reserve_range(mdr->address, mdr->length);
> + }
> +
> + txt_early_put_heap_table(mdrs, mdroffset + mdrslen - 8);
> +
> +nomdr:
> + slaunch_txt_reserve_range(ap_wake_info.ap_wake_block,
> + ap_wake_info.ap_wake_block_size);
> +
> + /*
> + * Earlier checks ensured that the event log was properly situated
> + * either inside the TXT heap or outside. This is a check to see if the
> + * event log needs to be reserved. If it is in the TXT heap, it is
> + * already reserved.
> + */
> + if (evtlog_addr < heap_base || evtlog_addr > (heap_base + heap_size))
> + slaunch_txt_reserve_range(evtlog_addr, evtlog_size);
> +
> + for (i = 0; i < e820_table->nr_entries; i++) {
> + base = e820_table->entries[i].addr;
> + size = e820_table->entries[i].size;
> + if ((base >= vtd_pmr_lo_size) && (base < 0x100000000ULL))
> + slaunch_txt_reserve_range(base, size);
> + else if ((base < vtd_pmr_lo_size) &&
> + (base + size > vtd_pmr_lo_size))
> + slaunch_txt_reserve_range(vtd_pmr_lo_size,
> + base + size - vtd_pmr_lo_size);
> + }
> +}
> +
> +/*
> + * TXT stashes a safe copy of the DMAR ACPI table to prevent tampering.
> + * It is stored in the TXT heap. Fetch it from there and make it available
> + * to the IOMMU driver.
> + */
> +static void __init slaunch_copy_dmar_table(void __iomem *txt)
> +{
> + struct txt_sinit_mle_data *sinit_mle_data;
> + u32 field_offset, dmar_size, dmar_offset;
> + void *dmar;
> +
> + memset(&txt_dmar, 0, PAGE_SIZE);
> +
> + field_offset = offsetof(struct txt_sinit_mle_data,
> + processor_scrtm_status);
> + sinit_mle_data = txt_early_get_heap_table(txt, TXT_SINIT_MLE_DATA_TABLE,
> + field_offset);
> +
> + dmar_size = sinit_mle_data->sinit_vtd_dmar_table_size;
> + dmar_offset = sinit_mle_data->sinit_vtd_dmar_table_offset;
> +
> + txt_early_put_heap_table(sinit_mle_data, field_offset);
> +
> + if (!dmar_size || !dmar_offset)
> + slaunch_txt_reset(txt,
> + "Error invalid DMAR table values\n",
> + SL_ERROR_HEAP_INVALID_DMAR);
> +
> + if (unlikely(dmar_size > PAGE_SIZE))
> + slaunch_txt_reset(txt,
> + "Error DMAR too big to store\n",
> + SL_ERROR_HEAP_DMAR_SIZE);
> +
> +
> + dmar = txt_early_get_heap_table(txt, TXT_SINIT_MLE_DATA_TABLE,
> + dmar_offset + dmar_size - 8);
> + if (!dmar)
> + slaunch_txt_reset(txt,
> + "Error early_ioremap of DMAR\n",
> + SL_ERROR_HEAP_DMAR_MAP);
> +
> + memcpy(&txt_dmar[0], dmar + dmar_offset - 8, dmar_size);
> +
> + txt_early_put_heap_table(dmar, dmar_offset + dmar_size - 8);
> +}
> +
> +/*
> + * The location of the safe AP wake code block is stored in the TXT heap.
> + * Fetch needed values here in the early init code for later use in SMP
> + * startup.
> + *
> + * Also get the TPM event log values are in the SLRT and have to be fetched.
> + * They will be put on the memblock reserve list later.
> + */
> +static void __init slaunch_fetch_values(void __iomem *txt)
> +{
> + struct txt_os_mle_data *os_mle_data;
> + struct slr_entry_log_info *log_info;
> + struct slr_table *slrt;
> + u8 *jmp_offset;
> + u32 size;
> +
> + os_mle_data = txt_early_get_heap_table(txt, TXT_OS_MLE_DATA_TABLE,
> + sizeof(*os_mle_data));
> +
> + ap_wake_info.ap_wake_block = os_mle_data->ap_wake_block;
> + ap_wake_info.ap_wake_block_size = os_mle_data->ap_wake_block_size;
> +
> + jmp_offset = os_mle_data->mle_scratch + SL_SCRATCH_AP_JMP_OFFSET;
> + ap_wake_info.ap_jmp_offset = *((u32 *)jmp_offset);
> +
> + slrt = (struct slr_table *)early_memremap(os_mle_data->slrt, sizeof(*slrt));
> + if (!slrt)
> + slaunch_txt_reset(txt,
> + "Error early_memremap of SLRT failed\n",
> + SL_ERROR_SLRT_MAP);
> +
> + size = slrt->size;
> + early_memunmap(slrt, sizeof(*slrt));
> +
> + slrt = (struct slr_table *)early_memremap(os_mle_data->slrt, size);
> + if (!slrt)
> + slaunch_txt_reset(txt,
> + "Error early_memremap of SLRT failed\n",
> + SL_ERROR_SLRT_MAP);
> +
> + log_info = (struct slr_entry_log_info *)
> + slr_next_entry_by_tag(slrt, NULL, SLR_ENTRY_LOG_INFO);
> +
> + if (!log_info)
> + slaunch_txt_reset(txt,
> + "SLRT missing logging info entry\n",
> + SL_ERROR_SLRT_MISSING_ENTRY);
> +
> + evtlog_addr = log_info->addr;
> + evtlog_size = log_info->size;
> +
> + early_memunmap(slrt, size);
> +
> + txt_early_put_heap_table(os_mle_data, sizeof(*os_mle_data));
> +}
> +
> +/*
> + * Intel TXT specific late stub setup and validation.
> + */
> +void __init slaunch_setup_txt(void)
> +{
> + u64 one = TXT_REGVALUE_ONE, val;
> + void __iomem *txt;
> +
> + if (!boot_cpu_has(X86_FEATURE_SMX))
> + return;
> +
> + /*
> + * If booted through secure launch entry point, the loadflags
> + * option will be set.
> + */
> + if (!(boot_params.hdr.loadflags & SLAUNCH_FLAG))
> + return;
> +
> + /*
> + * See if SENTER was done by reading the status register in the
> + * public space. If the public register space cannot be read, TXT may
> + * be disabled.
> + */
> + txt = early_ioremap(TXT_PUB_CONFIG_REGS_BASE,
> + TXT_NR_CONFIG_PAGES * PAGE_SIZE);
> + if (!txt)
> + return;
> +
> + memcpy_fromio(&val, txt + TXT_CR_STS, sizeof(val));
> + early_iounmap(txt, TXT_NR_CONFIG_PAGES * PAGE_SIZE);
> +
> + /* SENTER should have been done */
> + if (!(val & TXT_SENTER_DONE_STS))
> + panic("Error TXT.STS SENTER_DONE not set\n");
> +
> + /* SEXIT should have been cleared */
> + if (val & TXT_SEXIT_DONE_STS)
> + panic("Error TXT.STS SEXIT_DONE set\n");
> +
> + /* Now we want to use the private register space */
> + txt = early_ioremap(TXT_PRIV_CONFIG_REGS_BASE,
> + TXT_NR_CONFIG_PAGES * PAGE_SIZE);
> + if (!txt) {
> + /* This is really bad, no where to go from here */
> + panic("Error early_ioremap of TXT priv registers\n");
> + }
> +
> + /*
> + * Try to read the Intel VID from the TXT private registers to see if
> + * TXT measured launch happened properly and the private space is
> + * available.
> + */
> + memcpy_fromio(&val, txt + TXT_CR_DIDVID, sizeof(val));
> + if ((val & 0xffff) != 0x8086) {
> + /*
> + * Can't do a proper TXT reset since it appears something is
> + * wrong even though SENTER happened and it should be in SMX
> + * mode.
> + */
> + panic("Invalid TXT vendor ID, not in SMX mode\n");
> + }
> +
> + /* Set flags so subsequent code knows the status of the launch */
> + sl_flags |= (SL_FLAG_ACTIVE|SL_FLAG_ARCH_TXT);
> +
> + /*
> + * Reading the proper DIDVID from the private register space means we
> + * are in SMX mode and private registers are open for read/write.
> + */
> +
> + /* On Intel, have to handle TPM localities via TXT */
> + memcpy_toio(txt + TXT_CR_CMD_SECRETS, &one, sizeof(one));
> + memcpy_fromio(&val, txt + TXT_CR_E2STS, sizeof(val));
> + memcpy_toio(txt + TXT_CR_CMD_OPEN_LOCALITY1, &one, sizeof(one));
> + memcpy_fromio(&val, txt + TXT_CR_E2STS, sizeof(val));
> +
> + slaunch_fetch_values(txt);
> +
> + slaunch_verify_pmrs(txt);
> +
> + slaunch_txt_reserve(txt);
> +
> + slaunch_copy_dmar_table(txt);
> +
> + early_iounmap(txt, TXT_NR_CONFIG_PAGES * PAGE_SIZE);
> +
> + pr_info("Intel TXT setup complete\n");
> +}
> diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
> index a3414af..5d1ac8d 100644
> --- a/drivers/iommu/intel/dmar.c
> +++ b/drivers/iommu/intel/dmar.c
> @@ -28,6 +28,7 @@
> #include <linux/iommu.h>
> #include <linux/numa.h>
> #include <linux/limits.h>
> +#include <linux/slaunch.h>
> #include <asm/irq_remapping.h>
>
> #include "iommu.h"
> @@ -660,6 +661,9 @@ static inline int dmar_walk_dmar_table(struct acpi_table_dmar *dmar,
> */
> dmar_tbl = tboot_get_dmar_table(dmar_tbl);
>
> + /* If Secure Launch is active, it has similar logic */
> + dmar_tbl = slaunch_get_dmar_table(dmar_tbl);
> +
> dmar = (struct acpi_table_dmar *)dmar_tbl;
> if (!dmar)
> return -ENODEV;
> --
> 1.8.3.1
Is it possible to test TXT in QEMU? Never done it so that's why I'm
asking.
BR, Jarkko
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