[PATCH v16 36/38] x86/slaunch: Secure Launch late initcall platform module

[Ross Philipson <ross.philipson@gmail.com>]

From: "Daniel P. Smith" <dpsmith@apertussolutions.com>

The Secure Launch platform module is a late init module. During the
init call, the TPM event log is read and measurements taken in the
early boot stub code are located. These measurements are extended
into the TPM PCRs using the mainline TPM kernel driver.

The platform module also registers the securityfs nodes to allow
fetching and writing events from/to the DRTM TPM event log. In
addition, on Intel, access to TXT register fields is made available
for reading.

Co-developed-by: garnetgrimm <grimmg@ainfosec.com>
Signed-off-by: garnetgrimm <grimmg@ainfosec.com>
Co-developed-by: Ross Philipson <ross.philipson@gmail.com>
Signed-off-by: Daniel P. Smith <dpsmith@apertussolutions.com>
Signed-off-by: Ross Philipson <ross.philipson@gmail.com>
---
 arch/x86/kernel/Makefile   |   1 +
 arch/x86/kernel/slmodule.c | 353 +++++++++++++++++++++++++++++++++++++
 2 files changed, 354 insertions(+)
 create mode 100644 arch/x86/kernel/slmodule.c

diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index bf2471701662..8b039ed0a902 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -98,6 +98,7 @@ obj-$(CONFIG_IA32_EMULATION)	+= tls.o
 obj-y				+= step.o
 obj-$(CONFIG_INTEL_TXT)		+= tboot.o
 obj-$(CONFIG_SECURE_LAUNCH)	+= slaunch.o
+obj-$(CONFIG_SECURE_LAUNCH)	+= slmodule.o
 obj-$(CONFIG_ISA_DMA_API)	+= i8237.o
 obj-y				+= stacktrace.o
 obj-y				+= cpu/
diff --git a/arch/x86/kernel/slmodule.c b/arch/x86/kernel/slmodule.c
new file mode 100644
index 000000000000..9688249e274c
--- /dev/null
+++ b/arch/x86/kernel/slmodule.c
@@ -0,0 +1,353 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Secure Launch late validation/setup, securityfs exposure and finalization.
+ *
+ * Copyright (c) 2026 Apertus Solutions, LLC
+ * Copyright (c) 2026 Assured Information Security, Inc.
+ * Copyright (c) 2026, Oracle and/or its affiliates.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/fs.h>
+#include <linux/init.h>
+#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 <linux/tpm.h>
+#include <asm/segment.h>
+#include <asm/sections.h>
+#include <crypto/sha2.h>
+#include <linux/efi.h>
+#include <linux/slr_table.h>
+#include <linux/slaunch.h>
+
+/*
+ * The macro DECLARE_TXT_PUB_READ_U is used to read values from the TXT
+ * public registers as unsigned values.
+ */
+#define DECLARE_TXT_PUB_READ_U(size, fmt, msg_size)			\
+static ssize_t txt_pub_read_u##size(unsigned int offset,		\
+		loff_t *read_offset,					\
+		size_t read_len,					\
+		char __user *buf)					\
+{									\
+	char msg_buffer[msg_size];					\
+	u##size reg_value = 0;						\
+	void __iomem *txt;						\
+									\
+	txt = ioremap(TXT_PUB_CONFIG_REGS_BASE,				\
+			TXT_NR_CONFIG_PAGES * PAGE_SIZE);		\
+	if (!txt)							\
+		return -EFAULT;						\
+	memcpy_fromio(&reg_value, txt + offset, sizeof(u##size));	\
+	iounmap(txt);							\
+	snprintf(msg_buffer, msg_size, fmt, reg_value);			\
+	return simple_read_from_buffer(buf, read_len, read_offset,	\
+			&msg_buffer, msg_size);				\
+}
+
+DECLARE_TXT_PUB_READ_U(8, "%#04x\n", 6);
+DECLARE_TXT_PUB_READ_U(32, "%#010x\n", 12);
+DECLARE_TXT_PUB_READ_U(64, "%#018llx\n", 20);
+
+#define DECLARE_TXT_FOPS(reg_name, reg_offset, reg_size)		\
+static ssize_t txt_##reg_name##_read(struct file *flip,			\
+		char __user *buf, size_t read_len, loff_t *read_offset)	\
+{									\
+	return txt_pub_read_u##reg_size(reg_offset, read_offset,	\
+			read_len, buf);					\
+}									\
+static const struct file_operations reg_name##_ops = {			\
+	.read = txt_##reg_name##_read,					\
+}
+
+DECLARE_TXT_FOPS(sts, TXT_CR_STS, 64);
+DECLARE_TXT_FOPS(ests, TXT_CR_ESTS, 8);
+DECLARE_TXT_FOPS(errorcode, TXT_CR_ERRORCODE, 32);
+DECLARE_TXT_FOPS(didvid, TXT_CR_DIDVID, 64);
+DECLARE_TXT_FOPS(e2sts, TXT_CR_E2STS, 64);
+DECLARE_TXT_FOPS(ver_emif, TXT_CR_VER_EMIF, 32);
+DECLARE_TXT_FOPS(scratchpad, TXT_CR_SCRATCHPAD, 64);
+
+/*
+ * Securityfs exposure
+ */
+struct memfile {
+	char *name;
+	void *addr;
+	size_t size;
+};
+
+static struct memfile sl_evtlog = { "eventlog", NULL, 0 };
+static void *txt_heap;
+static struct txt_heap_event_log_pointer2_1_element *evtlog21;
+static DEFINE_MUTEX(sl_evt_log_mutex);
+static struct tcg_efi_specid_event_head *efi_head;
+
+static ssize_t sl_evtlog_read(struct file *file, char __user *buf,
+			      size_t count, loff_t *pos)
+{
+	ssize_t size;
+
+	if (!sl_evtlog.addr)
+		return 0;
+
+	mutex_lock(&sl_evt_log_mutex);
+	size = simple_read_from_buffer(buf, count, pos, sl_evtlog.addr,
+				       sl_evtlog.size);
+	mutex_unlock(&sl_evt_log_mutex);
+
+	return size;
+}
+
+static ssize_t sl_evtlog_write(struct file *file, const char __user *buf,
+			       size_t datalen, loff_t *ppos)
+{
+	ssize_t result;
+	char *data;
+
+	if (!sl_evtlog.addr)
+		return 0;
+
+	/* No partial writes. */
+	result = -EINVAL;
+	if (*ppos != 0)
+		goto out;
+
+	data = memdup_user(buf, datalen);
+	if (IS_ERR(data)) {
+		result = PTR_ERR(data);
+		goto out;
+	}
+
+	mutex_lock(&sl_evt_log_mutex);
+	if (evtlog21)
+		result = tpm2_log_event(evtlog21, sl_evtlog.addr,
+					sl_evtlog.size, datalen, data);
+	else
+		result = tpm_log_event(sl_evtlog.addr, sl_evtlog.size,
+				       datalen, data);
+	mutex_unlock(&sl_evt_log_mutex);
+
+	kfree(data);
+out:
+	return result;
+}
+
+static const struct file_operations sl_evtlog_ops = {
+	.read = sl_evtlog_read,
+	.write = sl_evtlog_write,
+	.llseek = default_llseek,
+};
+
+struct sfs_file {
+	const char *name;
+	const struct file_operations *fops;
+};
+
+#define SL_TXT_ENTRY_COUNT	7
+static const struct sfs_file sl_txt_files[] = {
+	{ "sts", &sts_ops },
+	{ "ests", &ests_ops },
+	{ "errorcode", &errorcode_ops },
+	{ "didvid", &didvid_ops },
+	{ "ver_emif", &ver_emif_ops },
+	{ "scratchpad", &scratchpad_ops },
+	{ "e2sts", &e2sts_ops }
+};
+
+/* sysfs file handles */
+static struct dentry *slaunch_dir;
+static struct dentry *event_file;
+static struct dentry *txt_dir;
+static struct dentry *txt_entries[SL_TXT_ENTRY_COUNT];
+
+static long slaunch_expose_securityfs(void)
+{
+	long ret = 0;
+	int i;
+
+	slaunch_dir = securityfs_create_dir("slaunch", NULL);
+	if (IS_ERR(slaunch_dir))
+		return PTR_ERR(slaunch_dir);
+
+	if (slaunch_get_flags() & SL_FLAG_ARCH_TXT) {
+		txt_dir = securityfs_create_dir("txt", slaunch_dir);
+		if (IS_ERR(txt_dir)) {
+			ret = PTR_ERR(txt_dir);
+			goto remove_slaunch;
+		}
+
+		for (i = 0; i < ARRAY_SIZE(sl_txt_files); i++) {
+			txt_entries[i] =
+				securityfs_create_file(sl_txt_files[i].name, 0440, txt_dir,
+						       NULL, sl_txt_files[i].fops);
+			if (IS_ERR(txt_entries[i])) {
+				ret = PTR_ERR(txt_entries[i]);
+				goto remove_files;
+			}
+		}
+	}
+
+	if (sl_evtlog.addr) {
+		event_file = securityfs_create_file(sl_evtlog.name, 0440,
+						    slaunch_dir, NULL,
+						    &sl_evtlog_ops);
+		if (IS_ERR(event_file)) {
+			ret = PTR_ERR(event_file);
+			goto remove_files;
+		}
+	}
+
+	return 0;
+
+remove_files:
+	if (slaunch_get_flags() & SL_FLAG_ARCH_TXT) {
+		while (--i >= 0)
+			securityfs_remove(txt_entries[i]);
+		securityfs_remove(txt_dir);
+	}
+
+remove_slaunch:
+	securityfs_remove(slaunch_dir);
+
+	return ret;
+}
+
+static void slaunch_teardown_securityfs(void)
+{
+	int i;
+
+	securityfs_remove(event_file);
+	if (sl_evtlog.addr) {
+		memunmap(sl_evtlog.addr);
+		sl_evtlog.addr = NULL;
+	}
+	sl_evtlog.size = 0;
+
+	if (slaunch_get_flags() & SL_FLAG_ARCH_TXT) {
+		for (i = 0; i < ARRAY_SIZE(sl_txt_files); i++)
+			securityfs_remove(txt_entries[i]);
+
+		securityfs_remove(txt_dir);
+
+		if (txt_heap) {
+			memunmap(txt_heap);
+			txt_heap = NULL;
+		}
+	}
+
+	securityfs_remove(slaunch_dir);
+}
+
+static void __init slaunch_intel_evtlog(void __iomem *txt)
+{
+	struct slr_entry_log_info *log_info;
+	struct txt_os_mle_data *params;
+	struct slr_table *slrt;
+	void *os_sinit_data;
+	u64 base, size;
+
+	memcpy_fromio(&base, txt + TXT_CR_HEAP_BASE, sizeof(base));
+	memcpy_fromio(&size, txt + TXT_CR_HEAP_SIZE, sizeof(size));
+
+	/* now map TXT heap */
+	txt_heap = memremap(base, size, MEMREMAP_WB);
+	if (!txt_heap)
+		slaunch_reset(txt, "Error memremap TXT heap failed\n", SL_ERROR_HEAP_MAP);
+
+	params = (struct txt_os_mle_data *)slaunch_txt_get_heap_table(txt_heap,
+								      TXT_OS_MLE_DATA_TABLE);
+
+	/* Get the SLRT and remap it */
+	slrt = memremap(params->slrt, sizeof(*slrt), MEMREMAP_WB);
+	if (!slrt)
+		slaunch_reset(txt, "Error memremap SLR Table failed\n", SL_ERROR_SLRT_MAP);
+	size = slrt->size;
+	memunmap(slrt);
+
+	slrt = memremap(params->slrt, size, MEMREMAP_WB);
+	if (!slrt)
+		slaunch_reset(txt, "Error memremap SLR Table failed\n", SL_ERROR_SLRT_MAP);
+
+	log_info = slr_next_entry_by_tag(slrt, NULL, SLR_ENTRY_LOG_INFO);
+	if (!log_info)
+		slaunch_reset(txt, "Error SLR Table missing entry\n", SL_ERROR_SLRT_MISSING_ENTRY);
+
+	sl_evtlog.size = log_info->size;
+	sl_evtlog.addr = memremap(log_info->addr, log_info->size, MEMREMAP_WB);
+	if (!sl_evtlog.addr)
+		slaunch_reset(txt, "Error memremap TPM event log failed\n", SL_ERROR_EVENTLOG_MAP);
+
+	memunmap(slrt);
+
+	/* Determine if this is TPM 1.2 or 2.0 event log */
+	if (memcmp(sl_evtlog.addr + sizeof(struct tcg_pcr_event),
+		   TCG_SPECID_SIG, sizeof(TCG_SPECID_SIG)))
+		return; /* looks like it is not 2.0 */
+
+	/* For TPM 2.0 logs, the extended heap element must be located */
+	os_sinit_data = slaunch_txt_get_heap_table(txt_heap, TXT_OS_SINIT_DATA_TABLE);
+
+	evtlog21 = txt_find_log2_1_element(os_sinit_data);
+
+	/*
+	 * If this fails, things are in really bad shape. Any attempt to write
+	 * events to the log will fail.
+	 */
+	if (!evtlog21)
+		slaunch_reset(txt, "Error locate TPM20 event log element failed\n",
+			      SL_ERROR_TPM_INVALID_LOG20);
+
+	/* Save pointer to the EFI SpecID log header */
+	efi_head = (struct tcg_efi_specid_event_head *)(sl_evtlog.addr +
+							sizeof(struct tcg_pcr_event));
+}
+
+static void __init slaunch_tpm_open_locality2(void __iomem *txt)
+{
+	struct tpm_chip *tpm;
+	int rc;
+
+	tpm = tpm_default_chip();
+	if (!tpm)
+		slaunch_reset(txt, "Could not get default TPM chip\n", SL_ERROR_TPM_INIT);
+
+	rc = tpm_chip_set_locality(tpm, 2);
+	if (rc)
+		slaunch_reset(txt, "Could not set TPM chip locality 2\n", SL_ERROR_TPM_INIT);
+}
+
+static int __init slaunch_module_init(void)
+{
+	void __iomem *txt;
+
+	/* Check to see if Secure Launch happened */
+	if ((slaunch_get_flags() & (SL_FLAG_ACTIVE|SL_FLAG_ARCH_TXT)) !=
+	    (SL_FLAG_ACTIVE | SL_FLAG_ARCH_TXT))
+		return 0;
+
+	txt = ioremap(TXT_PRIV_CONFIG_REGS_BASE, TXT_NR_CONFIG_PAGES *
+		      PAGE_SIZE);
+	if (!txt)
+		panic("Error ioremap of TXT priv registers\n");
+
+	/* Only Intel TXT is supported at this point */
+	slaunch_intel_evtlog(txt);
+	slaunch_tpm_open_locality2(txt);
+	iounmap(txt);
+
+	return slaunch_expose_securityfs();
+}
+
+static void __exit slaunch_module_exit(void)
+{
+	slaunch_teardown_securityfs();
+}
+
+late_initcall(slaunch_module_init);
+__exitcall(slaunch_module_exit);
-- 
2.47.3