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From:   Ross Philipson <ross.philipson@oracle.com>
To:     linux-kernel@vger.kernel.org, x86@kernel.org,
        iommu@lists.linux-foundation.org, linux-integrity@vger.kernel.org,
        linux-doc@vger.kernel.org
Cc:     ross.philipson@oracle.com, dpsmith@apertussolutions.com,
        tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com,
        luto@amacapital.net, trenchboot-devel@googlegroups.com
Subject: [PATCH 10/13] x86: Secure Launch adding event log securityfs
Date:   Thu, 24 Sep 2020 10:58:38 -0400
Message-Id: <1600959521-24158-11-git-send-email-ross.philipson@oracle.com>
In-Reply-To: <1600959521-24158-1-git-send-email-ross.philipson@oracle.com>
References: <1600959521-24158-1-git-send-email-ross.philipson@oracle.com>
Precedence: bulk

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

The late init functionality registers securityfs nodes to allow access
to TXT register fields on Intel along with the fetching of and writing
events to the late launch TPM log.

Signed-off-by: Daniel P. Smith <dpsmith@apertussolutions.com>
Signed-off-by: Ross Philipson <ross.philipson@oracle.com>
Signed-off-by: garnetgrimm <grimmg@ainfosec.com>
---
 arch/x86/kernel/slaunch.c | 293 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 292 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/slaunch.c b/arch/x86/kernel/slaunch.c
index e040e32..7bdb89e 100644
--- a/arch/x86/kernel/slaunch.c
+++ b/arch/x86/kernel/slaunch.c
@@ -8,7 +8,7 @@
  *
  * Author(s):
  *     Daniel P. Smith <dpsmith@apertussolutions.com>
- *
+ *     Garnet T. Grimm <grimmg@ainfosec.com>
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -493,3 +493,294 @@ void __init slaunch_setup(void)
 	    vendor[3] == INTEL_CPUID_MFGID_EDX)
 		slaunch_setup_intel();
 }
+
+#define SL_FS_ENTRIES		10
+/* root directory node must be last */
+#define SL_ROOT_DIR_ENTRY	(SL_FS_ENTRIES - 1)
+#define SL_TXT_DIR_ENTRY	(SL_FS_ENTRIES - 2)
+#define SL_TXT_FILE_FIRST	(SL_TXT_DIR_ENTRY - 1)
+#define SL_TXT_ENTRY_COUNT	7
+
+#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)					\
+{									\
+	void __iomem *txt;						\
+	char msg_buffer[msg_size];					\
+	u##size reg_value = 0;						\
+	txt = ioremap(TXT_PUB_CONFIG_REGS_BASE,				\
+			TXT_NR_CONFIG_PAGES * PAGE_SIZE);		\
+	if (IS_ERR(txt))						\
+		return PTR_ERR(txt);					\
+	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", 0, 0};
+static void *txt_heap;
+static struct txt_heap_event_log_pointer2_1_element __iomem *evtlog20;
+static DEFINE_MUTEX(sl_evt_log_mutex);
+
+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)
+{
+	char *data;
+	ssize_t result;
+
+	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 (evtlog20)
+		result = tpm20_log_event(evtlog20, sl_evtlog.addr,
+					 datalen, data);
+	else
+		result = tpm12_log_event(sl_evtlog.addr, 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,
+};
+
+static struct dentry *fs_entries[SL_FS_ENTRIES];
+
+struct sfs_file {
+	int parent;
+	const char *name;
+	const struct file_operations *fops;
+};
+
+static const struct sfs_file sl_files[] = {
+	{ SL_TXT_DIR_ENTRY, "sts", &sts_ops },
+	{ SL_TXT_DIR_ENTRY, "ests", &ests_ops },
+	{ SL_TXT_DIR_ENTRY, "errorcode", &errorcode_ops },
+	{ SL_TXT_DIR_ENTRY, "didvid", &didvid_ops },
+	{ SL_TXT_DIR_ENTRY, "ver_emif", &ver_emif_ops },
+	{ SL_TXT_DIR_ENTRY, "scratchpad", &scratchpad_ops },
+	{ SL_TXT_DIR_ENTRY, "e2sts", &e2sts_ops }
+};
+
+static int sl_create_file(int entry, int parent, const char *name,
+		const struct file_operations *ops)
+{
+	if (entry < 0 || entry > SL_TXT_DIR_ENTRY)
+		return -EINVAL;
+	fs_entries[entry] = securityfs_create_file(name, 0440,
+			fs_entries[parent], NULL, ops);
+	if (IS_ERR(fs_entries[entry])) {
+		pr_err("Error creating securityfs %s file\n", name);
+		return PTR_ERR(fs_entries[entry]);
+	}
+	return 0;
+}
+
+static long slaunch_expose_securityfs(void)
+{
+	long ret = 0;
+	int i = 0;
+
+	fs_entries[SL_ROOT_DIR_ENTRY] = securityfs_create_dir("slaunch", NULL);
+	if (IS_ERR(fs_entries[SL_ROOT_DIR_ENTRY])) {
+		pr_err("Error creating securityfs slaunch root directory\n");
+		ret = PTR_ERR(fs_entries[SL_ROOT_DIR_ENTRY]);
+		goto err;
+	}
+
+	if (sl_flags & SL_FLAG_ARCH_TXT) {
+		fs_entries[SL_TXT_DIR_ENTRY] = securityfs_create_dir("txt",
+				fs_entries[SL_ROOT_DIR_ENTRY]);
+		if (IS_ERR(fs_entries[SL_TXT_DIR_ENTRY])) {
+			pr_err("Error creating securityfs txt directory\n");
+			ret = PTR_ERR(fs_entries[SL_TXT_DIR_ENTRY]);
+			goto err_dir;
+		}
+
+		for (i = 0; i < SL_TXT_ENTRY_COUNT; i++) {
+			ret = sl_create_file(SL_TXT_FILE_FIRST - i,
+					sl_files[i].parent, sl_files[i].name,
+					sl_files[i].fops);
+			if (ret)
+				goto err_dir;
+		}
+	}
+
+	if (sl_evtlog.addr > 0) {
+		ret = sl_create_file(0, SL_ROOT_DIR_ENTRY, sl_evtlog.name,
+				&sl_evtlog_ops);
+		if (ret)
+			goto err_dir;
+	}
+
+	return 0;
+
+err_dir:
+	for (i = 0; i <= SL_ROOT_DIR_ENTRY; i++)
+		securityfs_remove(fs_entries[i]);
+err:
+	return ret;
+}
+
+static void slaunch_teardown_securityfs(void)
+{
+	int i;
+
+	for (i = 0; i < SL_FS_ENTRIES; i++)
+		securityfs_remove(fs_entries[i]);
+
+	if (sl_flags & SL_FLAG_ARCH_TXT) {
+		if (sl_evtlog.addr) {
+			memunmap(sl_evtlog.addr);
+			sl_evtlog.addr = NULL;
+		}
+		sl_evtlog.size = 0;
+		if (txt_heap) {
+			memunmap(txt_heap);
+			txt_heap = NULL;
+		}
+	}
+}
+
+static void slaunch_intel_evtlog(void)
+{
+	void __iomem *config;
+	struct txt_os_mle_data *params;
+	void *os_sinit_data;
+	u64 base, size;
+
+	config = ioremap(TXT_PUB_CONFIG_REGS_BASE, TXT_NR_CONFIG_PAGES *
+			 PAGE_SIZE);
+	if (!config) {
+		pr_err("Error failed to ioremap TXT reqs\n");
+		return;
+	}
+
+	memcpy_fromio(&base, config + TXT_CR_HEAP_BASE, sizeof(u64));
+	memcpy_fromio(&size, config + TXT_CR_HEAP_SIZE, sizeof(u64));
+	iounmap(config);
+
+	/* now map TXT heap */
+	txt_heap = memremap(base, size, MEMREMAP_WB);
+	if (!txt_heap) {
+		pr_err("Error failed to memremap TXT heap\n");
+		return;
+	}
+
+	params = (struct txt_os_mle_data *)txt_os_mle_data_start(txt_heap);
+
+	sl_evtlog.size = params->evtlog_size;
+	sl_evtlog.addr = memremap(params->evtlog_addr, params->evtlog_size,
+				  MEMREMAP_WB);
+	if (!sl_evtlog.addr) {
+		pr_err("Error failed to memremap TPM event log\n");
+		return;
+	}
+
+	/* Determine if this is TPM 1.2 or 2.0 event log */
+	if (memcmp(sl_evtlog.addr + sizeof(struct tpm12_pcr_event),
+		    TPM20_EVTLOG_SIGNATURE, sizeof(TPM20_EVTLOG_SIGNATURE)))
+		return; /* looks like it is not 2.0 */
+
+	/* For TPM 2.0 logs, the extended heap element must be located */
+	os_sinit_data = txt_os_sinit_data_start(txt_heap);
+
+	evtlog20 = tpm20_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 (!evtlog20)
+		pr_err("Error failed to find TPM20 event log element\n");
+}
+
+static int __init slaunch_late_init(void)
+{
+	/* Check to see if Secure Launch happened */
+	if (!(sl_flags & (SL_FLAG_ACTIVE|SL_FLAG_ARCH_TXT)))
+		return 0;
+
+	/* Only Intel TXT is supported at this point */
+	slaunch_intel_evtlog();
+
+	return slaunch_expose_securityfs();
+}
+
+static void __exit slaunch_exit(void)
+{
+	slaunch_teardown_securityfs();
+}
+
+late_initcall(slaunch_late_init);
+
+__exitcall(slaunch_exit);
-- 
1.8.3.1