Re: [tpmdd-devel] [PATCH v7 07/10] tpm: TPM 2.0 baseline support

From: Jarkko Sakkinen
Date: Mon Dec 01 2014 - 12:55:46 EST

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On Tue, Nov 25, 2014 at 07:42:25PM -0500, Stefan Berger wrote:
> On 11/11/2014 08:45 AM, Jarkko Sakkinen wrote:
> >TPM 2.0 devices are separated by adding a field 'flags' to struct
> >tpm_chip and defining a flag TPM_CHIP_FLAG_TPM2 for tagging them.
> >
> >This patch adds the following internal functions:
> >
> >- tpm2_get_random()
> >- tpm2_get_tpm_pt()
> >- tpm2_pcr_extend()
> >- tpm2_pcr_read()
> >- tpm2_startup()
> >
> >Additionally, the following exported functions are implemented for
> >implementing TPM 2.0 device drivers:
> >
> >- tpm2_do_selftest()
> >- tpm2_calc_ordinal_durations()
> >- tpm2_gen_interrupt()
> >
> >The existing functions that are exported for the use for existing
> >subsystems have been changed to check the flags field in struct
> >tpm_chip and use appropriate TPM 2.0 counterpart if
> >TPM_CHIP_FLAG_TPM2 is est.
> >
> >The code for tpm2_calc_ordinal_duration() and tpm2_startup() were
> >originally written by Will Arthur.
> >
> >Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
> >Signed-off-by: Will Arthur <will.c.arthur@xxxxxxxxx>
> >---
> > drivers/char/tpm/Makefile | 2 +-
> > drivers/char/tpm/tpm-chip.c | 21 +-
> > drivers/char/tpm/tpm-interface.c | 24 +-
> > drivers/char/tpm/tpm.h | 67 +++++
> > drivers/char/tpm/tpm2-cmd.c | 566 +++++++++++++++++++++++++++++++++++++++
> > 5 files changed, 668 insertions(+), 12 deletions(-)
> > create mode 100644 drivers/char/tpm/tpm2-cmd.c
> >
> >diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
> >index 837da04..ae56af9 100644
> >--- a/drivers/char/tpm/Makefile
> >+++ b/drivers/char/tpm/Makefile
> >@@ -2,7 +2,7 @@
> > # Makefile for the kernel tpm device drivers.
> > #
> > obj-$(CONFIG_TCG_TPM) += tpm.o
> >-tpm-y := tpm-interface.o tpm-dev.o tpm-sysfs.o tpm-chip.o
> >+tpm-y := tpm-interface.o tpm-dev.o tpm-sysfs.o tpm-chip.o tpm2-cmd.o
> > tpm-$(CONFIG_ACPI) += tpm_ppi.o
> >
> > ifdef CONFIG_ACPI
> >diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> >index 5d268ac..4d25b24 100644
> >--- a/drivers/char/tpm/tpm-chip.c
> >+++ b/drivers/char/tpm/tpm-chip.c
> >@@ -213,11 +213,14 @@ int tpm_chip_register(struct tpm_chip *chip)
> > if (rc)
> > return rc;
> >
> >- rc = tpm_add_ppi(chip);
> >- if (rc)
> >- goto out_err;
> >+ /* Populate sysfs for TPM1 devices. */
> >+ if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
> >+ rc = tpm_add_ppi(chip);
> >+ if (rc)
> >+ goto out_err;
> >
> >- chip->bios_dir = tpm_bios_log_setup(chip->devname);
> >+ chip->bios_dir = tpm_bios_log_setup(chip->devname);
> >+ }
> >
> > /* Make the chip available. */
> > spin_lock(&driver_lock);
> >@@ -248,10 +251,12 @@ void tpm_chip_unregister(struct tpm_chip *chip)
> > spin_unlock(&driver_lock);
> > synchronize_rcu();
> >
> >- tpm_remove_ppi(chip);
> >-
> >- if (chip->bios_dir)
> >- tpm_bios_log_teardown(chip->bios_dir);
> >+ /* Clean up sysfs for TPM1 devices. */
> >+ if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
> >+ if (chip->bios_dir)
> >+ tpm_bios_log_teardown(chip->bios_dir);
> >+ tpm_remove_ppi(chip);
> >+ }
> >
> > tpm_dev_del_device(chip);
> > }
> >diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> >index 9e4ce4d..e62b835 100644
> >--- a/drivers/char/tpm/tpm-interface.c
> >+++ b/drivers/char/tpm/tpm-interface.c
> >@@ -360,7 +360,10 @@ ssize_t tpm_transmit(struct tpm_chip *chip, const char *buf,
> > if (chip->vendor.irq)
> > goto out_recv;
> >
> >- stop = jiffies + tpm_calc_ordinal_duration(chip, ordinal);
> >+ if (chip->flags & TPM_CHIP_FLAG_TPM2)
> >+ stop = jiffies + tpm2_calc_ordinal_duration(chip, ordinal);
> >+ else
> >+ stop = jiffies + tpm_calc_ordinal_duration(chip, ordinal);
> > do {
> > u8 status = chip->ops->status(chip);
> > if ((status & chip->ops->req_complete_mask) ==
> >@@ -483,7 +486,7 @@ static const struct tpm_input_header tpm_startup_header = {
> > static int tpm_startup(struct tpm_chip *chip, __be16 startup_type)
> > {
> > struct tpm_cmd_t start_cmd;
> >- start_cmd.header.in = tpm_startup_header;
> >+
> > start_cmd.params.startup_in.startup_type = startup_type;
> > return tpm_transmit_cmd(chip, &start_cmd, TPM_INTERNAL_RESULT_SIZE,
> > "attempting to start the TPM");
> >@@ -680,7 +683,10 @@ int tpm_pcr_read(u32 chip_num, int pcr_idx, u8 *res_buf)
> > chip = tpm_chip_find_get(chip_num);
> > if (chip == NULL)
> > return -ENODEV;
> >- rc = tpm_pcr_read_dev(chip, pcr_idx, res_buf);
> >+ if (chip->flags & TPM_CHIP_FLAG_TPM2)
> >+ rc = tpm2_pcr_read(chip, pcr_idx, res_buf);
> >+ else
> >+ rc = tpm_pcr_read_dev(chip, pcr_idx, res_buf);
> > tpm_chip_put(chip);
> > return rc;
> > }
> >@@ -714,6 +720,12 @@ int tpm_pcr_extend(u32 chip_num, int pcr_idx, const u8 *hash)
> > if (chip == NULL)
> > return -ENODEV;
> >
> >+ if (chip->flags & TPM_CHIP_FLAG_TPM2) {
> >+ rc = tpm2_pcr_extend(chip, pcr_idx, hash);
> >+ tpm_chip_put(chip);
> >+ return rc;
> >+ }
> >+
> > cmd.header.in = pcrextend_header;
> > cmd.params.pcrextend_in.pcr_idx = cpu_to_be32(pcr_idx);
> > memcpy(cmd.params.pcrextend_in.hash, hash, TPM_DIGEST_SIZE);
> >@@ -974,6 +986,12 @@ int tpm_get_random(u32 chip_num, u8 *out, size_t max)
> > if (chip == NULL)
> > return -ENODEV;
> >
> >+ if (chip->flags & TPM_CHIP_FLAG_TPM2) {
> >+ err = tpm2_get_random(chip, out, max);
> >+ tpm_chip_put(chip);
> >+ return err;
> >+ }
> >+
> > do {
> > tpm_cmd.header.in = tpm_getrandom_header;
> > tpm_cmd.params.getrandom_in.num_bytes = cpu_to_be32(num_bytes);
> >diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> >index 9d062e6..8a434d2 100644
> >--- a/drivers/char/tpm/tpm.h
> >+++ b/drivers/char/tpm/tpm.h
> >@@ -62,6 +62,57 @@ enum tpm_duration {
> > #define TPM_ERR_INVALID_POSTINIT 38
> >
> > #define TPM_HEADER_SIZE 10
> >+
> >+enum tpm2_const {
> >+ TPM2_PLATFORM_PCR = 24,
> >+ TPM2_PCR_SELECT_MIN = ((TPM2_PLATFORM_PCR + 7) / 8),
> >+ TPM2_TIMEOUT_A = 750 * 1000,
> >+ TPM2_TIMEOUT_B = 2000 * 1000,
> >+ TPM2_TIMEOUT_C = 200 * 1000,
> >+ TPM2_TIMEOUT_D = 30 * 1000,
> >+ TPM2_DURATION_SHORT = 20 * 1000,
> >+ TPM2_DURATION_MEDIUM = 750 * 1000,
> >+ TPM2_DURATION_LONG = 2000 * 1000,
> >+};
> >+
> >+enum tpm2_structures {
> >+ TPM2_ST_NO_SESSIONS = 0x8001,
> >+ TPM2_ST_SESSIONS = 0x8002,
> >+};
> >+
> >+enum tpm2_return_codes {
> >+ TPM2_RC_TESTING = 0x090A,
> >+ TPM2_RC_DISABLED = 0x0120,
> >+};
> >+
> >+enum tpm2_algorithms {
> >+ TPM2_ALG_SHA1 = 0x0004,
> >+};
> >+
> >+enum tpm2_command_codes {
> >+ TPM2_CC_FIRST = 0x011F,
> >+ TPM2_CC_SELF_TEST = 0x0143,
> >+ TPM2_CC_STARTUP = 0x0144,
> >+ TPM2_CC_GET_CAPABILITY = 0x017A,
> >+ TPM2_CC_GET_RANDOM = 0x017B,
> >+ TPM2_CC_PCR_READ = 0x017E,
> >+ TPM2_CC_PCR_EXTEND = 0x0182,
> >+ TPM2_CC_LAST = 0x018F,
> >+};
> >+
> >+enum tpm2_permanent_handles {
> >+ TPM2_RS_PW = 0x40000009,
> >+};
> >+
> >+enum tpm2_capabilities {
> >+ TPM2_CAP_TPM_PROPERTIES = 6,
> >+};
> >+
> >+enum tpm2_startup_types {
> >+ TPM2_SU_CLEAR = 0x0000,
> >+ TPM2_SU_STATE = 0x0001,
> >+};
> >+
> > struct tpm_chip;
> >
> > struct tpm_vendor_specific {
> >@@ -96,12 +147,17 @@ struct tpm_vendor_specific {
> >
> > #define TPM_PPI_VERSION_LEN 3
> >
> >+enum tpm_chip_flags {
> >+ TPM_CHIP_FLAG_TPM2 = BIT(0),
> >+};
> >+
> > struct tpm_chip {
> > struct device *pdev; /* Device stuff */
> > struct device dev;
> > struct cdev cdev;
> >
> > const struct tpm_class_ops *ops;
> >+ unsigned int flags;
> >
> > int dev_num; /* /dev/tpm# */
> > char devname[7];
> >@@ -362,3 +418,14 @@ static inline void tpm_remove_ppi(struct tpm_chip *chip)
> > {
> > }
> > #endif
> >+
> >+int tpm2_startup(struct tpm_chip *chip, __be16 startup_type);
> >+int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx, u8 *res_buf);
> >+int tpm2_pcr_extend(struct tpm_chip *chip, int pcr_idx, const u8 *hash);
> >+int tpm2_get_random(struct tpm_chip *chip, u8 *out, size_t max);
> >+
> >+extern ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id,
> >+ u32 *value, const char *desc);
> >+extern unsigned long tpm2_calc_ordinal_duration(struct tpm_chip *, u32);
> >+extern int tpm2_do_selftest(struct tpm_chip *chip);
> >+extern int tpm2_gen_interrupt(struct tpm_chip *chip);
> >diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> >new file mode 100644
> >index 0000000..458a17d
> >--- /dev/null
> >+++ b/drivers/char/tpm/tpm2-cmd.c
> >@@ -0,0 +1,566 @@
> >+/*
> >+ * Copyright (C) 2014 Intel Corporation
> >+ *
> >+ * Authors:
> >+ * Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
> >+ *
> >+ * Maintained by: <tpmdd-devel@xxxxxxxxxxxxxxxxxxxxx>
> >+ *
> >+ * This file contains TPM2 protocol implementations of the commands
> >+ * used by the kernel internally.
> >+ *
> >+ * This program is free software; you can redistribute it and/or
> >+ * modify it under the terms of the GNU General Public License
> >+ * as published by the Free Software Foundation; version 2
> >+ * of the License.
> >+ */
> >+
> >+#include "tpm.h"
> >+
> >+struct tpm2_startup_in {
> >+ __be16 startup_type;
> >+} __packed;
> >+
> >+struct tpm2_self_test_in {
> >+ u8 full_test;
> >+} __packed;
> >+
> >+struct tpm2_pcr_read_in {
> >+ __be32 pcr_selects_cnt;
> >+ __be16 hash_alg;
> >+ u8 pcr_select_size;
> >+ u8 pcr_select[TPM2_PCR_SELECT_MIN];
> >+} __packed;
> >+
> >+struct tpm2_pcr_read_out {
> >+ __be32 update_cnt;
> >+ __be32 pcr_selects_cnt;
> >+ __be16 hash_alg;
> >+ u8 pcr_select_size;
> >+ u8 pcr_select[TPM2_PCR_SELECT_MIN];
> >+ __be32 digests_cnt;
> >+ __be16 digest_size;
> >+ u8 digest[TPM_DIGEST_SIZE];
> >+} __packed;
> >+
> >+struct tpm2_null_auth_area {
> >+ __be32 handle;
> >+ __be16 nonce_size;
> >+ u8 attributes;
> >+ __be16 auth_size;
> >+} __packed;
> >+
> >+struct tpm2_pcr_extend_in {
> >+ __be32 pcr_idx;
> >+ __be32 auth_area_size;
> >+ struct tpm2_null_auth_area auth_area;
> >+ __be32 digest_cnt;
> >+ __be16 hash_alg;
> >+ u8 digest[TPM_DIGEST_SIZE];
> >+} __packed;
> >+
> >+struct tpm2_get_tpm_pt_in {
> >+ __be32 cap_id;
> >+ __be32 property_id;
> >+ __be32 property_cnt;
> >+} __packed;
> >+
> >+struct tpm2_get_tpm_pt_out {
> >+ u8 more_data;
> >+ __be32 subcap_id;
> >+ __be32 property_cnt;
> >+ __be32 property_id;
> >+ __be32 value;
> >+} __packed;
> >+
> >+struct tpm2_get_random_in {
> >+ __be16 size;
> >+} __packed;
> >+
> >+struct tpm2_get_random_out {
> >+ __be16 size;
> >+ u8 buffer[TPM_MAX_RNG_DATA];
> >+} __packed;
> >+
> >+union tpm2_cmd_params {
> >+ struct tpm2_startup_in startup_in;
> >+ struct tpm2_self_test_in selftest_in;
> >+ struct tpm2_pcr_read_in pcrread_in;
> >+ struct tpm2_pcr_read_out pcrread_out;
> >+ struct tpm2_pcr_extend_in pcrextend_in;
> >+ struct tpm2_get_tpm_pt_in get_tpm_pt_in;
> >+ struct tpm2_get_tpm_pt_out get_tpm_pt_out;
> >+ struct tpm2_get_random_in getrandom_in;
> >+ struct tpm2_get_random_out getrandom_out;
> >+};
> >+
> >+struct tpm2_cmd {
> >+ tpm_cmd_header header;
> >+ union tpm2_cmd_params params;
> >+} __packed;
> >+
> >+/*
> >+ * Array with one entry per ordinal defining the maximum amount
> >+ * of time the chip could take to return the result. The values
> >+ * of the SHORT, MEDIUM, and LONG durations are taken from the
> >+ * PC Client Profile (PTP) specification.
> >+ */
> >+static const u8 tpm2_ordinal_duration[TPM2_CC_LAST - TPM2_CC_FIRST + 1] = {
> >+ TPM_UNDEFINED, /* 11F */
> >+ TPM_UNDEFINED, /* 120 */
> >+ TPM_LONG, /* 121 */
> >+ TPM_UNDEFINED, /* 122 */
> >+ TPM_UNDEFINED, /* 123 */
> >+ TPM_UNDEFINED, /* 124 */
> >+ TPM_UNDEFINED, /* 125 */
> >+ TPM_UNDEFINED, /* 126 */
> >+ TPM_UNDEFINED, /* 127 */
> >+ TPM_UNDEFINED, /* 128 */
> >+ TPM_LONG, /* 129 */
> >+ TPM_UNDEFINED, /* 12a */
> >+ TPM_UNDEFINED, /* 12b */
> >+ TPM_UNDEFINED, /* 12c */
> >+ TPM_UNDEFINED, /* 12d */
> >+ TPM_UNDEFINED, /* 12e */
> >+ TPM_UNDEFINED, /* 12f */
> >+ TPM_UNDEFINED, /* 130 */
> >+ TPM_UNDEFINED, /* 131 */
> >+ TPM_UNDEFINED, /* 132 */
> >+ TPM_UNDEFINED, /* 133 */
> >+ TPM_UNDEFINED, /* 134 */
> >+ TPM_UNDEFINED, /* 135 */
> >+ TPM_UNDEFINED, /* 136 */
> >+ TPM_UNDEFINED, /* 137 */
> >+ TPM_UNDEFINED, /* 138 */
> >+ TPM_UNDEFINED, /* 139 */
> >+ TPM_UNDEFINED, /* 13a */
> >+ TPM_UNDEFINED, /* 13b */
> >+ TPM_UNDEFINED, /* 13c */
> >+ TPM_UNDEFINED, /* 13d */
> >+ TPM_MEDIUM, /* 13e */
> >+ TPM_UNDEFINED, /* 13f */
> >+ TPM_UNDEFINED, /* 140 */
> >+ TPM_UNDEFINED, /* 141 */
> >+ TPM_UNDEFINED, /* 142 */
> >+ TPM_LONG, /* 143 */
> >+ TPM_MEDIUM, /* 144 */
> >+ TPM_UNDEFINED, /* 145 */
> >+ TPM_UNDEFINED, /* 146 */
> >+ TPM_UNDEFINED, /* 147 */
> >+ TPM_UNDEFINED, /* 148 */
> >+ TPM_UNDEFINED, /* 149 */
> >+ TPM_UNDEFINED, /* 14a */
> >+ TPM_UNDEFINED, /* 14b */
> >+ TPM_UNDEFINED, /* 14c */
> >+ TPM_UNDEFINED, /* 14d */
> >+ TPM_LONG, /* 14e */
> >+ TPM_UNDEFINED, /* 14f */
> >+ TPM_UNDEFINED, /* 150 */
> >+ TPM_UNDEFINED, /* 151 */
> >+ TPM_UNDEFINED, /* 152 */
> >+ TPM_UNDEFINED, /* 153 */
> >+ TPM_UNDEFINED, /* 154 */
> >+ TPM_UNDEFINED, /* 155 */
> >+ TPM_UNDEFINED, /* 156 */
> >+ TPM_UNDEFINED, /* 157 */
> >+ TPM_UNDEFINED, /* 158 */
> >+ TPM_UNDEFINED, /* 159 */
> >+ TPM_UNDEFINED, /* 15a */
> >+ TPM_UNDEFINED, /* 15b */
> >+ TPM_MEDIUM, /* 15c */
> >+ TPM_UNDEFINED, /* 15d */
> >+ TPM_UNDEFINED, /* 15e */
> >+ TPM_UNDEFINED, /* 15f */
> >+ TPM_UNDEFINED, /* 160 */
> >+ TPM_UNDEFINED, /* 161 */
> >+ TPM_UNDEFINED, /* 162 */
> >+ TPM_UNDEFINED, /* 163 */
> >+ TPM_UNDEFINED, /* 164 */
> >+ TPM_UNDEFINED, /* 165 */
> >+ TPM_UNDEFINED, /* 166 */
> >+ TPM_UNDEFINED, /* 167 */
> >+ TPM_UNDEFINED, /* 168 */
> >+ TPM_UNDEFINED, /* 169 */
> >+ TPM_UNDEFINED, /* 16a */
> >+ TPM_UNDEFINED, /* 16b */
> >+ TPM_UNDEFINED, /* 16c */
> >+ TPM_UNDEFINED, /* 16d */
> >+ TPM_UNDEFINED, /* 16e */
> >+ TPM_UNDEFINED, /* 16f */
> >+ TPM_UNDEFINED, /* 170 */
> >+ TPM_UNDEFINED, /* 171 */
> >+ TPM_UNDEFINED, /* 172 */
> >+ TPM_UNDEFINED, /* 173 */
> >+ TPM_UNDEFINED, /* 174 */
> >+ TPM_UNDEFINED, /* 175 */
> >+ TPM_UNDEFINED, /* 176 */
> >+ TPM_LONG, /* 177 */
> >+ TPM_UNDEFINED, /* 178 */
> >+ TPM_UNDEFINED, /* 179 */
> >+ TPM_MEDIUM, /* 17a */
> >+ TPM_LONG, /* 17b */
> >+ TPM_UNDEFINED, /* 17c */
> >+ TPM_UNDEFINED, /* 17d */
> >+ TPM_UNDEFINED, /* 17e */
> >+ TPM_UNDEFINED, /* 17f */
> >+ TPM_UNDEFINED, /* 180 */
> >+ TPM_UNDEFINED, /* 181 */
> >+ TPM_MEDIUM, /* 182 */
> >+ TPM_UNDEFINED, /* 183 */
> >+ TPM_UNDEFINED, /* 184 */
> >+ TPM_MEDIUM, /* 185 */
> >+ TPM_MEDIUM, /* 186 */
> >+ TPM_UNDEFINED, /* 187 */
> >+ TPM_UNDEFINED, /* 188 */
> >+ TPM_UNDEFINED, /* 189 */
> >+ TPM_UNDEFINED, /* 18a */
> >+ TPM_UNDEFINED, /* 18b */
> >+ TPM_UNDEFINED, /* 18c */
> >+ TPM_UNDEFINED, /* 18d */
> >+ TPM_UNDEFINED, /* 18e */
> >+ TPM_UNDEFINED /* 18f */
> >+};
> >+
> >+static const struct tpm_input_header tpm2_startup_header = {
> >+ .tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
> >+ .length = cpu_to_be32(12),
>
> 12 -> sizeof(struct tpm_input_header) + sizeof(struct pm2_startup_in)
>
> >+ .ordinal = cpu_to_be32(TPM2_CC_STARTUP)
> >+};
> >+
> >+/**
> >+ * tpm2_startup() - send startup command to the TPM chip
> >+ * @chip: TPM chip to use.
> >+ * @startup_type startup type. The value is either
> >+ * TPM_SU_CLEAR or TPM_SU_STATE.
> >+ *
> >+ * 0 is returned when the operation is successful. When a negative number is
> >+ * returned it remarks a POSIX error code. When a positive number is returned
> >+ * it remarks a TPM error.
>
> Replace 'When's with 'If's. (when being 'temporal')
>
> >+ */
> >+int tpm2_startup(struct tpm_chip *chip, __be16 startup_type)
> >+{
> >+ struct tpm2_cmd cmd;
> >+
> >+ cmd.header.in = tpm2_startup_header;
> >+
> >+ cmd.params.startup_in.startup_type = startup_type;
> >+ return tpm_transmit_cmd(chip, &cmd, sizeof(cmd),
> >+ "attempting to start the TPM");
> >+}
> >+
> >+#define TPM2_PCR_READ_IN_SIZE \
> >+ (sizeof(struct tpm_input_header) + \
> >+ sizeof(struct tpm2_pcr_read_in))
> >+
>
> Ah! You could also use a #define above!
>
> >+static const struct tpm_input_header tpm2_pcrread_header = {
> >+ .tag = cpu_to_be16(TPM2_ST_NO_SESSIONS),
> >+ .length = cpu_to_be32(TPM2_PCR_READ_IN_SIZE),
> >+ .ordinal = cpu_to_be32(TPM2_CC_PCR_READ)
> >+};
> >+
> >+/**
> >+ * tpm2_pcr_read() - read a PCR value
> >+ * @chip: TPM chip to use.
> >+ * @pcr_idx: index of the PCR to read.
> >+ * @ref_buf: buffer to store the resulting hash,
> >+ *
> >+ * 0 is returned when the operation is successful. When a negative number is
> >+ * returned it remarks a POSIX error code. When a positive number is returned
> >+ * it remarks a TPM error.
> >+ */
>
> Replace 'When's with 'If's. Also further below.
>
> >+int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx, u8 *res_buf)
> >+{
> >+ int rc;
> >+ struct tpm2_cmd cmd;
> >+ u8 *buf;
> >+ int i, j;
> >+
> >+ if (pcr_idx >= TPM2_PLATFORM_PCR)
> >+ return -EINVAL;
> >+
> >+ cmd.header.in = tpm2_pcrread_header;
> >+ cmd.params.pcrread_in.pcr_selects_cnt = cpu_to_be32(1);
> >+ cmd.params.pcrread_in.hash_alg = cpu_to_be16(TPM2_ALG_SHA1);
> >+ cmd.params.pcrread_in.pcr_select_size = TPM2_PCR_SELECT_MIN;
> >+
> >+ for (i = 0; i < TPM2_PCR_SELECT_MIN; i++) {
> >+ j = pcr_idx - i * 8;
> >+
> >+ cmd.params.pcrread_in.pcr_select[i] =
> >+ (j >= 0 && j < 8) ? 1 << j : 0;
> >+ }
>
> Umpf - what's this? You need to set the PCR index as an index in the
> bitfield?
>
> pcr_idx >> 3 gives you the index into the array, assuming that [0] holds
> bits for PCR0 to 7.
>
> 1 << (pcr_idx & 0x7) gives you the bit to set, assuming bit 0 is to be set
> for PCR 0
> 1 << (7- (pcr_idx & 0x7)) gives you the bit to set, assuming bit 7 is to be
> set for PCR 0.
>
> memset(cmd.params.pcrread_in.pcr_select, 0,
> sizeof(cmd.params.pcrread_in.pcr_select));
> cmd.params.pcrread_in.pcr_select[pcr_idx >> 3] = 1 << (pcr_idx & 0x7);

Just sloppy and ugly code that nobody has commented so far and since it has
worked I haven't really give it much thought :) Will definitely clean
that mess, thanks.

/Jarkko
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