Merge branch 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

Pull general security subsystem updates from James Morris:
 "TPM (from Jarkko):
   - essential clean up for tpm_crb so that ARM64 and x86 versions do
     not distract each other as much as before

   - /dev/tpm0 rejects now too short writes (shorter buffer than
     specified in the command header

   - use DMA-safe buffer in tpm_tis_spi

   - otherwise mostly minor fixes.

  Smack:
   - base support for overlafs

  Capabilities:
   - BPRM_FCAPS fixes, from Richard Guy Briggs:

     The audit subsystem is adding a BPRM_FCAPS record when auditing
     setuid application execution (SYSCALL execve). This is not expected
     as it was supposed to be limited to when the file system actually
     had capabilities in an extended attribute. It lists all
     capabilities making the event really ugly to parse what is
     happening. The PATH record correctly records the setuid bit and
     owner. Suppress the BPRM_FCAPS record on set*id.

  TOMOYO:
   - Y2038 timestamping fixes"

* 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (28 commits)
  MAINTAINERS: update the IMA, EVM, trusted-keys, encrypted-keys entries
  Smack: Base support for overlayfs
  MAINTAINERS: remove David Safford as maintainer for encrypted+trusted keys
  tomoyo: fix timestamping for y2038
  capabilities: audit log other surprising conditions
  capabilities: fix logic for effective root or real root
  capabilities: invert logic for clarity
  capabilities: remove a layer of conditional logic
  capabilities: move audit log decision to function
  capabilities: use intuitive names for id changes
  capabilities: use root_priveleged inline to clarify logic
  capabilities: rename has_cap to has_fcap
  capabilities: intuitive names for cap gain status
  capabilities: factor out cap_bprm_set_creds privileged root
  tpm, tpm_tis: use ARRAY_SIZE() to define TPM_HID_USR_IDX
  tpm: fix duplicate inline declaration specifier
  tpm: fix type of a local variables in tpm_tis_spi.c
  tpm: fix type of a local variable in tpm2_map_command()
  tpm: fix type of a local variable in tpm2_get_cc_attrs_tbl()
  tpm-dev-common: Reject too short writes
  ...

10 files changed, 161 insertions, 171 deletions

diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c
index 610638a80383..461bf0b8a094 100644
--- a/drivers/char/tpm/tpm-dev-common.c
+++ b/drivers/char/tpm/tpm-dev-common.c
@@ -110,6 +110,12 @@ ssize_t tpm_common_write(struct file *file, const char __user *buf,
 		return -EFAULT;
 	}
 
+	if (in_size < 6 ||
+	    in_size < be32_to_cpu(*((__be32 *) (priv->data_buffer + 2)))) {
+		mutex_unlock(&priv->buffer_mutex);
+		return -EINVAL;
+	}
+
 	/* atomic tpm command send and result receive. We only hold the ops
 	 * lock during this period so that the tpm can be unregistered even if
 	 * the char dev is held open.
diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
index 86f38d239476..83a77a445538 100644
--- a/drivers/char/tpm/tpm-sysfs.c
+++ b/drivers/char/tpm/tpm-sysfs.c
@@ -20,44 +20,48 @@
 #include <linux/device.h>
 #include "tpm.h"
 
-#define READ_PUBEK_RESULT_SIZE 314
+struct tpm_readpubek_out {
+	u8 algorithm[4];
+	u8 encscheme[2];
+	u8 sigscheme[2];
+	__be32 paramsize;
+	u8 parameters[12];
+	__be32 keysize;
+	u8 modulus[256];
+	u8 checksum[20];
+} __packed;
+
 #define READ_PUBEK_RESULT_MIN_BODY_SIZE (28 + 256)
 #define TPM_ORD_READPUBEK 124
-static const struct tpm_input_header tpm_readpubek_header = {
-	.tag = cpu_to_be16(TPM_TAG_RQU_COMMAND),
-	.length = cpu_to_be32(30),
-	.ordinal = cpu_to_be32(TPM_ORD_READPUBEK)
-};
+
 static ssize_t pubek_show(struct device *dev, struct device_attribute *attr,
 			  char *buf)
 {
-	u8 *data;
-	struct tpm_cmd_t tpm_cmd;
-	ssize_t err;
-	int i, rc;
+	struct tpm_buf tpm_buf;
+	struct tpm_readpubek_out *out;
+	ssize_t rc;
+	int i;
 	char *str = buf;
 	struct tpm_chip *chip = to_tpm_chip(dev);
+	char anti_replay[20];
 
-	memset(&tpm_cmd, 0, sizeof(tpm_cmd));
-
-	tpm_cmd.header.in = tpm_readpubek_header;
-	err = tpm_transmit_cmd(chip, NULL, &tpm_cmd, READ_PUBEK_RESULT_SIZE,
-			       READ_PUBEK_RESULT_MIN_BODY_SIZE, 0,
-			       "attempting to read the PUBEK");
-	if (err)
-		goto out;
-
-	/*
-	   ignore header 10 bytes
-	   algorithm 32 bits (1 == RSA )
-	   encscheme 16 bits
-	   sigscheme 16 bits
-	   parameters (RSA 12->bytes: keybit, #primes, expbit)
-	   keylenbytes 32 bits
-	   256 byte modulus
-	   ignore checksum 20 bytes
-	 */
-	data = tpm_cmd.params.readpubek_out_buffer;
+	memset(&anti_replay, 0, sizeof(anti_replay));
+
+	rc = tpm_buf_init(&tpm_buf, TPM_TAG_RQU_COMMAND, TPM_ORD_READPUBEK);
+	if (rc)
+		return rc;
+
+	tpm_buf_append(&tpm_buf, anti_replay, sizeof(anti_replay));
+
+	rc = tpm_transmit_cmd(chip, NULL, tpm_buf.data, PAGE_SIZE,
+			      READ_PUBEK_RESULT_MIN_BODY_SIZE, 0,
+			      "attempting to read the PUBEK");
+	if (rc) {
+		tpm_buf_destroy(&tpm_buf);
+		return 0;
+	}
+
+	out = (struct tpm_readpubek_out *)&tpm_buf.data[10];
 	str +=
 	    sprintf(str,
 		    "Algorithm: %02X %02X %02X %02X\n"
@@ -68,21 +72,26 @@ static ssize_t pubek_show(struct device *dev, struct device_attribute *attr,
 		    "%02X %02X %02X %02X\n"
 		    "Modulus length: %d\n"
 		    "Modulus:\n",
-		    data[0], data[1], data[2], data[3],
-		    data[4], data[5],
-		    data[6], data[7],
-		    data[12], data[13], data[14], data[15],
-		    data[16], data[17], data[18], data[19],
-		    data[20], data[21], data[22], data[23],
-		    be32_to_cpu(*((__be32 *) (data + 24))));
+		    out->algorithm[0], out->algorithm[1], out->algorithm[2],
+		    out->algorithm[3],
+		    out->encscheme[0], out->encscheme[1],
+		    out->sigscheme[0], out->sigscheme[1],
+		    out->parameters[0], out->parameters[1],
+		    out->parameters[2], out->parameters[3],
+		    out->parameters[4], out->parameters[5],
+		    out->parameters[6], out->parameters[7],
+		    out->parameters[8], out->parameters[9],
+		    out->parameters[10], out->parameters[11],
+		    be32_to_cpu(out->keysize));
 
 	for (i = 0; i < 256; i++) {
-		str += sprintf(str, "%02X ", data[i + 28]);
+		str += sprintf(str, "%02X ", out->modulus[i]);
 		if ((i + 1) % 16 == 0)
 			str += sprintf(str, "\n");
 	}
-out:
+
 	rc = str - buf;
+	tpm_buf_destroy(&tpm_buf);
 	return rc;
 }
 static DEVICE_ATTR_RO(pubek);
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 2d5466a72e40..528cffbd49d3 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -345,17 +345,6 @@ enum tpm_sub_capabilities {
 	TPM_CAP_PROP_TIS_DURATION = 0x120,
 };
 
-struct	tpm_readpubek_params_out {
-	u8	algorithm[4];
-	u8	encscheme[2];
-	u8	sigscheme[2];
-	__be32	paramsize;
-	u8	parameters[12]; /*assuming RSA*/
-	__be32	keysize;
-	u8	modulus[256];
-	u8	checksum[20];
-} __packed;
-
 typedef union {
 	struct	tpm_input_header in;
 	struct	tpm_output_header out;
@@ -385,8 +374,6 @@ struct tpm_getrandom_in {
 } __packed;
 
 typedef union {
-	struct	tpm_readpubek_params_out readpubek_out;
-	u8	readpubek_out_buffer[sizeof(struct tpm_readpubek_params_out)];
 	struct	tpm_pcrread_in	pcrread_in;
 	struct	tpm_pcrread_out	pcrread_out;
 	struct	tpm_getrandom_in getrandom_in;
@@ -557,7 +544,7 @@ static inline void tpm_add_ppi(struct tpm_chip *chip)
 }
 #endif
 
-static inline inline u32 tpm2_rc_value(u32 rc)
+static inline u32 tpm2_rc_value(u32 rc)
 {
 	return (rc & BIT(7)) ? rc & 0xff : rc;
 }
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index e1a41b788f08..f40d20671a78 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -834,72 +834,43 @@ static const struct tpm_input_header tpm2_selftest_header = {
 };
 
 /**
- * tpm2_continue_selftest() - start a self test
- *
- * @chip: TPM chip to use
- * @full: test all commands instead of testing only those that were not
- *        previously tested.
- *
- * Return: Same as with tpm_transmit_cmd with exception of RC_TESTING.
- */
-static int tpm2_start_selftest(struct tpm_chip *chip, bool full)
-{
-	int rc;
-	struct tpm2_cmd cmd;
-
-	cmd.header.in = tpm2_selftest_header;
-	cmd.params.selftest_in.full_test = full;
-
-	rc = tpm_transmit_cmd(chip, NULL, &cmd, TPM2_SELF_TEST_IN_SIZE, 0, 0,
-			      "continue selftest");
-
-	/* At least some prototype chips seem to give RC_TESTING error
-	 * immediately. This is a workaround for that.
-	 */
-	if (rc == TPM2_RC_TESTING) {
-		dev_warn(&chip->dev, "Got RC_TESTING, ignoring\n");
-		rc = 0;
-	}
-
-	return rc;
-}
-
-/**
- * tpm2_do_selftest() - run a full self test
+ * tpm2_do_selftest() - ensure that all self tests have passed
  *
  * @chip: TPM chip to use
  *
  * Return: Same as with tpm_transmit_cmd.
  *
- * During the self test TPM2 commands return with the error code RC_TESTING.
- * Waiting is done by issuing PCR read until it executes successfully.
+ * The TPM can either run all self tests synchronously and then return
+ * RC_SUCCESS once all tests were successful. Or it can choose to run the tests
+ * asynchronously and return RC_TESTING immediately while the self tests still
+ * execute in the background. This function handles both cases and waits until
+ * all tests have completed.
  */
 static int tpm2_do_selftest(struct tpm_chip *chip)
 {
 	int rc;
-	unsigned int loops;
-	unsigned int delay_msec = 100;
-	unsigned long duration;
-	int i;
-
-	duration = tpm2_calc_ordinal_duration(chip, TPM2_CC_SELF_TEST);
+	unsigned int delay_msec = 20;
+	long duration;
+	struct tpm2_cmd cmd;
 
-	loops = jiffies_to_msecs(duration) / delay_msec;
+	duration = jiffies_to_msecs(
+		tpm2_calc_ordinal_duration(chip, TPM2_CC_SELF_TEST));
 
-	rc = tpm2_start_selftest(chip, true);
-	if (rc)
-		return rc;
+	while (duration > 0) {
+		cmd.header.in = tpm2_selftest_header;
+		cmd.params.selftest_in.full_test = 0;
 
-	for (i = 0; i < loops; i++) {
-		/* Attempt to read a PCR value */
-		rc = tpm2_pcr_read(chip, 0, NULL);
-		if (rc < 0)
-			break;
+		rc = tpm_transmit_cmd(chip, NULL, &cmd, TPM2_SELF_TEST_IN_SIZE,
+				      0, 0, "continue selftest");
 
 		if (rc != TPM2_RC_TESTING)
 			break;
 
 		tpm_msleep(delay_msec);
+		duration -= delay_msec;
+
+		/* wait longer the next round */
+		delay_msec *= 2;
 	}
 
 	return rc;
@@ -1009,7 +980,7 @@ static int tpm2_get_cc_attrs_tbl(struct tpm_chip *chip)
 {
 	struct tpm_buf buf;
 	u32 nr_commands;
-	u32 *attrs;
+	__be32 *attrs;
 	u32 cc;
 	int i;
 	int rc;
@@ -1049,7 +1020,7 @@ static int tpm2_get_cc_attrs_tbl(struct tpm_chip *chip)
 
 	chip->nr_commands = nr_commands;
 
-	attrs = (u32 *)&buf.data[TPM_HEADER_SIZE + 9];
+	attrs = (__be32 *)&buf.data[TPM_HEADER_SIZE + 9];
 	for (i = 0; i < nr_commands; i++, attrs++) {
 		chip->cc_attrs_tbl[i] = be32_to_cpup(attrs);
 		cc = chip->cc_attrs_tbl[i] & 0xFFFF;
diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c
index e2e059d8ffec..4e4014eabdb9 100644
--- a/drivers/char/tpm/tpm2-space.c
+++ b/drivers/char/tpm/tpm2-space.c
@@ -242,7 +242,7 @@ static int tpm2_map_command(struct tpm_chip *chip, u32 cc, u8 *cmd)
 	struct tpm_space *space = &chip->work_space;
 	unsigned int nr_handles;
 	u32 attrs;
-	u32 *handle;
+	__be32 *handle;
 	int i;
 
 	i = tpm2_find_cc(chip, cc);
@@ -252,7 +252,7 @@ static int tpm2_map_command(struct tpm_chip *chip, u32 cc, u8 *cmd)
 	attrs = chip->cc_attrs_tbl[i];
 	nr_handles = (attrs >> TPM2_CC_ATTR_CHANDLES) & GENMASK(2, 0);
 
-	handle = (u32 *)&cmd[TPM_HEADER_SIZE];
+	handle = (__be32 *)&cmd[TPM_HEADER_SIZE];
 	for (i = 0; i < nr_handles; i++, handle++) {
 		if ((be32_to_cpu(*handle) & 0xFF000000) == TPM2_HT_TRANSIENT) {
 			if (!tpm2_map_to_phandle(space, handle))
diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
index 8f0a98dea327..7b3c2a8aa9de 100644
--- a/drivers/char/tpm/tpm_crb.c
+++ b/drivers/char/tpm/tpm_crb.c
@@ -92,14 +92,9 @@ enum crb_status {
 	CRB_DRV_STS_COMPLETE	= BIT(0),
 };
 
-enum crb_flags {
-	CRB_FL_ACPI_START	= BIT(0),
-	CRB_FL_CRB_START	= BIT(1),
-	CRB_FL_CRB_SMC_START	= BIT(2),
-};
-
 struct crb_priv {
-	unsigned int flags;
+	u32 sm;
+	const char *hid;
 	void __iomem *iobase;
 	struct crb_regs_head __iomem *regs_h;
 	struct crb_regs_tail __iomem *regs_t;
@@ -128,14 +123,16 @@ struct tpm2_crb_smc {
  * Anyhow, we do not wait here as a consequent CMD_READY request
  * will be handled correctly even if idle was not completed.
  *
- * The function does nothing for devices with ACPI-start method.
+ * The function does nothing for devices with ACPI-start method
+ * or SMC-start method.
  *
  * Return: 0 always
  */
 static int __maybe_unused crb_go_idle(struct device *dev, struct crb_priv *priv)
 {
-	if ((priv->flags & CRB_FL_ACPI_START) ||
-	    (priv->flags & CRB_FL_CRB_SMC_START))
+	if ((priv->sm == ACPI_TPM2_START_METHOD) ||
+	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD) ||
+	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC))
 		return 0;
 
 	iowrite32(CRB_CTRL_REQ_GO_IDLE, &priv->regs_t->ctrl_req);
@@ -174,14 +171,16 @@ static bool crb_wait_for_reg_32(u32 __iomem *reg, u32 mask, u32 value,
  * The device should respond within TIMEOUT_C.
  *
  * The function does nothing for devices with ACPI-start method
+ * or SMC-start method.
  *
  * Return: 0 on success -ETIME on timeout;
  */
 static int __maybe_unused crb_cmd_ready(struct device *dev,
 					struct crb_priv *priv)
 {
-	if ((priv->flags & CRB_FL_ACPI_START) ||
-	    (priv->flags & CRB_FL_CRB_SMC_START))
+	if ((priv->sm == ACPI_TPM2_START_METHOD) ||
+	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD) ||
+	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC))
 		return 0;
 
 	iowrite32(CRB_CTRL_REQ_CMD_READY, &priv->regs_t->ctrl_req);
@@ -325,13 +324,20 @@ static int crb_send(struct tpm_chip *chip, u8 *buf, size_t len)
 	/* Make sure that cmd is populated before issuing start. */
 	wmb();
 
-	if (priv->flags & CRB_FL_CRB_START)
+	/* The reason for the extra quirk is that the PTT in 4th Gen Core CPUs
+	 * report only ACPI start but in practice seems to require both
+	 * CRB start, hence invoking CRB start method if hid == MSFT0101.
+	 */
+	if ((priv->sm == ACPI_TPM2_COMMAND_BUFFER) ||
+	    (priv->sm == ACPI_TPM2_MEMORY_MAPPED) ||
+	    (!strcmp(priv->hid, "MSFT0101")))
 		iowrite32(CRB_START_INVOKE, &priv->regs_t->ctrl_start);
 
-	if (priv->flags & CRB_FL_ACPI_START)
+	if ((priv->sm == ACPI_TPM2_START_METHOD) ||
+	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD))
 		rc = crb_do_acpi_start(chip);
 
-	if (priv->flags & CRB_FL_CRB_SMC_START) {
+	if (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC) {
 		iowrite32(CRB_START_INVOKE, &priv->regs_t->ctrl_start);
 		rc = tpm_crb_smc_start(&chip->dev, priv->smc_func_id);
 	}
@@ -345,7 +351,9 @@ static void crb_cancel(struct tpm_chip *chip)
 
 	iowrite32(CRB_CANCEL_INVOKE, &priv->regs_t->ctrl_cancel);
 
-	if ((priv->flags & CRB_FL_ACPI_START) && crb_do_acpi_start(chip))
+	if (((priv->sm == ACPI_TPM2_START_METHOD) ||
+	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD)) &&
+	     crb_do_acpi_start(chip))
 		dev_err(&chip->dev, "ACPI Start failed\n");
 }
 
@@ -458,7 +466,8 @@ static int crb_map_io(struct acpi_device *device, struct crb_priv *priv,
 	 * the control area, as one nice sane region except for some older
 	 * stuff that puts the control area outside the ACPI IO region.
 	 */
-	if (!(priv->flags & CRB_FL_ACPI_START)) {
+	if ((priv->sm == ACPI_TPM2_COMMAND_BUFFER) ||
+	    (priv->sm == ACPI_TPM2_MEMORY_MAPPED)) {
 		if (buf->control_address == io_res.start +
 		    sizeof(*priv->regs_h))
 			priv->regs_h = priv->iobase;
@@ -552,18 +561,6 @@ static int crb_acpi_add(struct acpi_device *device)
 	if (!priv)
 		return -ENOMEM;
 
-	/* The reason for the extra quirk is that the PTT in 4th Gen Core CPUs
-	 * report only ACPI start but in practice seems to require both
-	 * ACPI start and CRB start.
-	 */
-	if (sm == ACPI_TPM2_COMMAND_BUFFER || sm == ACPI_TPM2_MEMORY_MAPPED ||
-	    !strcmp(acpi_device_hid(device), "MSFT0101"))
-		priv->flags |= CRB_FL_CRB_START;
-
-	if (sm == ACPI_TPM2_START_METHOD ||
-	    sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD)
-		priv->flags |= CRB_FL_ACPI_START;
-
 	if (sm == ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC) {
 		if (buf->header.length < (sizeof(*buf) + sizeof(*crb_smc))) {
 			dev_err(dev,
@@ -574,9 +571,11 @@ static int crb_acpi_add(struct acpi_device *device)
 		}
 		crb_smc = ACPI_ADD_PTR(struct tpm2_crb_smc, buf, sizeof(*buf));
 		priv->smc_func_id = crb_smc->smc_func_id;
-		priv->flags |= CRB_FL_CRB_SMC_START;
 	}
 
+	priv->sm = sm;
+	priv->hid = acpi_device_hid(device);
+
 	rc = crb_map_io(device, priv, buf);
 	if (rc)
 		return rc;
diff --git a/drivers/char/tpm/tpm_tis.c b/drivers/char/tpm/tpm_tis.c
index 7e55aa9ce680..e2d1055fb814 100644
--- a/drivers/char/tpm/tpm_tis.c
+++ b/drivers/char/tpm/tpm_tis.c
@@ -30,6 +30,7 @@
 #include <linux/freezer.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
+#include <linux/kernel.h>
 #include "tpm.h"
 #include "tpm_tis_core.h"
 
@@ -223,7 +224,7 @@ static int tpm_tcg_read_bytes(struct tpm_tis_data *data, u32 addr, u16 len,
 }
 
 static int tpm_tcg_write_bytes(struct tpm_tis_data *data, u32 addr, u16 len,
-			       u8 *value)
+			       const u8 *value)
 {
 	struct tpm_tis_tcg_phy *phy = to_tpm_tis_tcg_phy(data);
 
@@ -365,7 +366,7 @@ static struct pnp_driver tis_pnp_driver = {
 	},
 };
 
-#define TIS_HID_USR_IDX sizeof(tpm_pnp_tbl)/sizeof(struct pnp_device_id) -2
+#define TIS_HID_USR_IDX (ARRAY_SIZE(tpm_pnp_tbl) - 2)
 module_param_string(hid, tpm_pnp_tbl[TIS_HID_USR_IDX].id,
 		    sizeof(tpm_pnp_tbl[TIS_HID_USR_IDX].id), 0444);
 MODULE_PARM_DESC(hid, "Set additional specific HID for this driver to probe");
diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 63bc6c3b949e..fdde971bc810 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -252,7 +252,7 @@ out:
  * tpm.c can skip polling for the data to be available as the interrupt is
  * waited for here
  */
-static int tpm_tis_send_data(struct tpm_chip *chip, u8 *buf, size_t len)
+static int tpm_tis_send_data(struct tpm_chip *chip, const u8 *buf, size_t len)
 {
 	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
 	int rc, status, burstcnt;
@@ -343,7 +343,7 @@ static void disable_interrupts(struct tpm_chip *chip)
  * tpm.c can skip polling for the data to be available as the interrupt is
  * waited for here
  */
-static int tpm_tis_send_main(struct tpm_chip *chip, u8 *buf, size_t len)
+static int tpm_tis_send_main(struct tpm_chip *chip, const u8 *buf, size_t len)
 {
 	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
 	int rc;
@@ -445,7 +445,7 @@ static int probe_itpm(struct tpm_chip *chip)
 {
 	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
 	int rc = 0;
-	u8 cmd_getticks[] = {
+	static const u8 cmd_getticks[] = {
 		0x00, 0xc1, 0x00, 0x00, 0x00, 0x0a,
 		0x00, 0x00, 0x00, 0xf1
 	};
diff --git a/drivers/char/tpm/tpm_tis_core.h b/drivers/char/tpm/tpm_tis_core.h
index e2212f021a02..6bbac319ff3b 100644
--- a/drivers/char/tpm/tpm_tis_core.h
+++ b/drivers/char/tpm/tpm_tis_core.h
@@ -98,7 +98,7 @@ struct tpm_tis_phy_ops {
 	int (*read_bytes)(struct tpm_tis_data *data, u32 addr, u16 len,
 			  u8 *result);
 	int (*write_bytes)(struct tpm_tis_data *data, u32 addr, u16 len,
-			   u8 *value);
+			   const u8 *value);
 	int (*read16)(struct tpm_tis_data *data, u32 addr, u16 *result);
 	int (*read32)(struct tpm_tis_data *data, u32 addr, u32 *result);
 	int (*write32)(struct tpm_tis_data *data, u32 addr, u32 src);
@@ -128,7 +128,7 @@ static inline int tpm_tis_read32(struct tpm_tis_data *data, u32 addr,
 }
 
 static inline int tpm_tis_write_bytes(struct tpm_tis_data *data, u32 addr,
-				      u16 len, u8 *value)
+				      u16 len, const u8 *value)
 {
 	return data->phy_ops->write_bytes(data, addr, len, value);
 }
diff --git a/drivers/char/tpm/tpm_tis_spi.c b/drivers/char/tpm/tpm_tis_spi.c
index 88fe72ae967f..424ff2fde1f2 100644
--- a/drivers/char/tpm/tpm_tis_spi.c
+++ b/drivers/char/tpm/tpm_tis_spi.c
@@ -46,9 +46,7 @@
 struct tpm_tis_spi_phy {
 	struct tpm_tis_data priv;
 	struct spi_device *spi_device;
-
-	u8 tx_buf[4];
-	u8 rx_buf[4];
+	u8 *iobuf;
 };
 
 static inline struct tpm_tis_spi_phy *to_tpm_tis_spi_phy(struct tpm_tis_data *data)
@@ -57,7 +55,7 @@ static inline struct tpm_tis_spi_phy *to_tpm_tis_spi_phy(struct tpm_tis_data *da
 }
 
 static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
-				u8 *buffer, u8 direction)
+				u8 *in, const u8 *out)
 {
 	struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
 	int ret = 0;
@@ -71,14 +69,14 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
 	while (len) {
 		transfer_len = min_t(u16, len, MAX_SPI_FRAMESIZE);
 
-		phy->tx_buf[0] = direction | (transfer_len - 1);
-		phy->tx_buf[1] = 0xd4;
-		phy->tx_buf[2] = addr >> 8;
-		phy->tx_buf[3] = addr;
+		phy->iobuf[0] = (in ? 0x80 : 0) | (transfer_len - 1);
+		phy->iobuf[1] = 0xd4;
+		phy->iobuf[2] = addr >> 8;
+		phy->iobuf[3] = addr;
 
 		memset(&spi_xfer, 0, sizeof(spi_xfer));
-		spi_xfer.tx_buf = phy->tx_buf;
-		spi_xfer.rx_buf = phy->rx_buf;
+		spi_xfer.tx_buf = phy->iobuf;
+		spi_xfer.rx_buf = phy->iobuf;
 		spi_xfer.len = 4;
 		spi_xfer.cs_change = 1;
 
@@ -88,9 +86,9 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
 		if (ret < 0)
 			goto exit;
 
-		if ((phy->rx_buf[3] & 0x01) == 0) {
+		if ((phy->iobuf[3] & 0x01) == 0) {
 			// handle SPI wait states
-			phy->tx_buf[0] = 0;
+			phy->iobuf[0] = 0;
 
 			for (i = 0; i < TPM_RETRY; i++) {
 				spi_xfer.len = 1;
@@ -99,7 +97,7 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
 				ret = spi_sync_locked(phy->spi_device, &m);
 				if (ret < 0)
 					goto exit;
-				if (phy->rx_buf[0] & 0x01)
+				if (phy->iobuf[0] & 0x01)
 					break;
 			}
 
@@ -113,12 +111,12 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
 		spi_xfer.len = transfer_len;
 		spi_xfer.delay_usecs = 5;
 
-		if (direction) {
+		if (in) {
 			spi_xfer.tx_buf = NULL;
-			spi_xfer.rx_buf = buffer;
-		} else {
-			spi_xfer.tx_buf = buffer;
+		} else if (out) {
 			spi_xfer.rx_buf = NULL;
+			memcpy(phy->iobuf, out, transfer_len);
+			out += transfer_len;
 		}
 
 		spi_message_init(&m);
@@ -127,8 +125,12 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
 		if (ret < 0)
 			goto exit;
 
+		if (in) {
+			memcpy(in, phy->iobuf, transfer_len);
+			in += transfer_len;
+		}
+
 		len -= transfer_len;
-		buffer += transfer_len;
 	}
 
 exit:
@@ -139,40 +141,51 @@ exit:
 static int tpm_tis_spi_read_bytes(struct tpm_tis_data *data, u32 addr,
 				  u16 len, u8 *result)
 {
-	return tpm_tis_spi_transfer(data, addr, len, result, 0x80);
+	return tpm_tis_spi_transfer(data, addr, len, result, NULL);
 }
 
 static int tpm_tis_spi_write_bytes(struct tpm_tis_data *data, u32 addr,
-				   u16 len, u8 *value)
+				   u16 len, const u8 *value)
 {
-	return tpm_tis_spi_transfer(data, addr, len, value, 0);
+	return tpm_tis_spi_transfer(data, addr, len, NULL, value);
 }
 
 static int tpm_tis_spi_read16(struct tpm_tis_data *data, u32 addr, u16 *result)
 {
+	__le16 result_le;
 	int rc;
 
-	rc = data->phy_ops->read_bytes(data, addr, sizeof(u16), (u8 *)result);
+	rc = data->phy_ops->read_bytes(data, addr, sizeof(u16),
+				       (u8 *)&result_le);
 	if (!rc)
-		*result = le16_to_cpu(*result);
+		*result = le16_to_cpu(result_le);
+
 	return rc;
 }
 
 static int tpm_tis_spi_read32(struct tpm_tis_data *data, u32 addr, u32 *result)
 {
+	__le32 result_le;
 	int rc;
 
-	rc = data->phy_ops->read_bytes(data, addr, sizeof(u32), (u8 *)result);
+	rc = data->phy_ops->read_bytes(data, addr, sizeof(u32),
+				       (u8 *)&result_le);
 	if (!rc)
-		*result = le32_to_cpu(*result);
+		*result = le32_to_cpu(result_le);
+
 	return rc;
 }
 
 static int tpm_tis_spi_write32(struct tpm_tis_data *data, u32 addr, u32 value)
 {
-	value = cpu_to_le32(value);
-	return data->phy_ops->write_bytes(data, addr, sizeof(u32),
-					   (u8 *)&value);
+	__le32 value_le;
+	int rc;
+
+	value_le = cpu_to_le32(value);
+	rc = data->phy_ops->write_bytes(data, addr, sizeof(u32),
+					(u8 *)&value_le);
+
+	return rc;
 }
 
 static const struct tpm_tis_phy_ops tpm_spi_phy_ops = {
@@ -194,6 +207,10 @@ static int tpm_tis_spi_probe(struct spi_device *dev)
 
 	phy->spi_device = dev;
 
+	phy->iobuf = devm_kmalloc(&dev->dev, MAX_SPI_FRAMESIZE, GFP_KERNEL);
+	if (!phy->iobuf)
+		return -ENOMEM;
+
 	return tpm_tis_core_init(&dev->dev, &phy->priv, -1, &tpm_spi_phy_ops,
 				 NULL);
 }