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Message-Id: <20220504161439.1.I776854f47e3340cc2913ed4d8ecdd328048b73c3@changeid>
Date: Wed, 4 May 2022 16:20:53 -0700
From: Evan Green <evgreen@...omium.org>
To: linux-kernel@...r.kernel.org
Cc: Matthew Garrett <mgarrett@...ora.tech>, dlunev@...gle.com,
zohar@...ux.ibm.com, jejb@...ux.ibm.com,
linux-integrity@...r.kernel.org, corbet@....net, rjw@...ysocki.net,
gwendal@...omium.org, jarkko@...nel.org, linux-pm@...r.kernel.org,
Matthew Garrett <matthewgarrett@...gle.com>,
Matthew Garrett <mjg59@...gle.com>,
Evan Green <evgreen@...omium.org>, Hao Wu <hao.wu@...rik.com>,
Jason Gunthorpe <jgg@...pe.ca>,
Peter Huewe <peterhuewe@....de>, axelj <axelj@...s.com>
Subject: [PATCH 01/10] tpm: Add support for in-kernel resetting of PCRs
From: Matthew Garrett <matthewgarrett@...gle.com>
Add an internal command for resetting a PCR. This will be used by the
encrypted hibernation code to set PCR23 to a known value. The
hibernation code will seal the hibernation key with a policy specifying
PCR23 be set to this known value as a mechanism to ensure that the
hibernation key is genuine. But to do this repeatedly, resetting the PCR
is necessary as well.
From: Matthew Garrett <mjg59@...gle.com>
Signed-off-by: Matthew Garrett <mjg59@...gle.com>
Signed-off-by: Evan Green <evgreen@...omium.org>
---
Matthew's original version of this patch was at:
https://patchwork.kernel.org/patch/12096487/
drivers/char/tpm/tpm-interface.c | 28 +++++++++++++++++++++++++
drivers/char/tpm/tpm.h | 2 ++
drivers/char/tpm/tpm1-cmd.c | 34 ++++++++++++++++++++++++++++++
drivers/char/tpm/tpm2-cmd.c | 36 ++++++++++++++++++++++++++++++++
include/linux/tpm.h | 7 +++++++
5 files changed, 107 insertions(+)
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 1621ce8187052c..17b8643ee109c2 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -342,6 +342,34 @@ int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
}
EXPORT_SYMBOL_GPL(tpm_pcr_extend);
+/**
+ * tpm_pcr_reset - reset the specified PCR
+ * @chip: a &struct tpm_chip instance, %NULL for the default chip
+ * @pcr_idx: the PCR to be reset
+ *
+ * Return: same as with tpm_transmit_cmd()
+ */
+int tpm_pcr_reset(struct tpm_chip *chip, u32 pcr_idx)
+{
+ int rc;
+
+ chip = tpm_find_get_ops(chip);
+ if (!chip)
+ return -ENODEV;
+
+ if (chip->flags & TPM_CHIP_FLAG_TPM2) {
+ rc = tpm2_pcr_reset(chip, pcr_idx);
+ goto out;
+ }
+
+ rc = tpm1_pcr_reset(chip, pcr_idx, "attempting to reset a PCR");
+
+out:
+ tpm_put_ops(chip);
+ return rc;
+}
+EXPORT_SYMBOL_GPL(tpm_pcr_reset);
+
/**
* tpm_send - send a TPM command
* @chip: a &struct tpm_chip instance, %NULL for the default chip
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 2163c6ee0d364f..72b6c0873852c6 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -174,6 +174,7 @@ int tpm1_get_timeouts(struct tpm_chip *chip);
unsigned long tpm1_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal);
int tpm1_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash,
const char *log_msg);
+int tpm1_pcr_reset(struct tpm_chip *chip, u32 pcr_idx, const char *log_msg);
int tpm1_pcr_read(struct tpm_chip *chip, u32 pcr_idx, u8 *res_buf);
ssize_t tpm1_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap,
const char *desc, size_t min_cap_length);
@@ -216,6 +217,7 @@ int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
struct tpm_digest *digest, u16 *digest_size_ptr);
int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
struct tpm_digest *digests);
+int tpm2_pcr_reset(struct tpm_chip *chip, u32 pcr_idx);
int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max);
ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id,
u32 *value, const char *desc);
diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index f7dc986fa4a0a2..9b9ad1fc20ccfd 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -478,6 +478,40 @@ int tpm1_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash,
return rc;
}
+struct tpm_pcr_selection {
+ u16 size_of_select;
+ u8 pcr_select[3];
+} __packed;
+
+#define TPM_ORD_PCR_RESET 200
+int tpm1_pcr_reset(struct tpm_chip *chip, u32 pcr_idx, const char *log_msg)
+{
+ struct tpm_pcr_selection selection;
+ struct tpm_buf buf;
+ int i, rc;
+ char tmp;
+
+ rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_PCR_RESET);
+ if (rc)
+ return rc;
+
+ selection.size_of_select = 3;
+
+ for (i = 0; i < selection.size_of_select; i++) {
+ tmp = 0;
+ if (pcr_idx / 3 == i) {
+ pcr_idx -= i * 8;
+ tmp |= 1 << pcr_idx;
+ }
+ selection.pcr_select[i] = tmp;
+ }
+ tpm_buf_append(&buf, (u8 *)&selection, sizeof(selection));
+
+ rc = tpm_transmit_cmd(chip, &buf, sizeof(selection), log_msg);
+ tpm_buf_destroy(&buf);
+ return rc;
+}
+
#define TPM_ORD_GET_CAP 101
ssize_t tpm1_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap,
const char *desc, size_t min_cap_length)
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 4704fa553098b5..c0806b4447c8b2 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -269,6 +269,42 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
return rc;
}
+/**
+ * tpm2_pcr_reset() - reset a PCR
+ *
+ * @chip: TPM chip to use.
+ * @pcr_idx: index of the PCR.
+ *
+ * Return: Same as with tpm_transmit_cmd.
+ */
+int tpm2_pcr_reset(struct tpm_chip *chip, u32 pcr_idx)
+{
+ struct tpm_buf buf;
+ struct tpm2_null_auth_area auth_area;
+ int rc;
+
+ rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_RESET);
+ if (rc)
+ return rc;
+
+ tpm_buf_append_u32(&buf, pcr_idx);
+
+ auth_area.handle = cpu_to_be32(TPM2_RS_PW);
+ auth_area.nonce_size = 0;
+ auth_area.attributes = 0;
+ auth_area.auth_size = 0;
+
+ tpm_buf_append_u32(&buf, sizeof(struct tpm2_null_auth_area));
+ tpm_buf_append(&buf, (const unsigned char *)&auth_area,
+ sizeof(auth_area));
+
+ rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to reset a PCR");
+
+ tpm_buf_destroy(&buf);
+
+ return rc;
+}
+
struct tpm2_get_random_out {
__be16 size;
u8 buffer[TPM_MAX_RNG_DATA];
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index dfeb25a0362dee..8320cbac6f4009 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -219,6 +219,7 @@ enum tpm2_command_codes {
TPM2_CC_HIERARCHY_CONTROL = 0x0121,
TPM2_CC_HIERARCHY_CHANGE_AUTH = 0x0129,
TPM2_CC_CREATE_PRIMARY = 0x0131,
+ TPM2_CC_PCR_RESET = 0x013D,
TPM2_CC_SEQUENCE_COMPLETE = 0x013E,
TPM2_CC_SELF_TEST = 0x0143,
TPM2_CC_STARTUP = 0x0144,
@@ -423,6 +424,7 @@ extern ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_buf *buf,
size_t min_rsp_body_length, const char *desc);
extern int tpm_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
struct tpm_digest *digest);
+extern int tpm_pcr_reset(struct tpm_chip *chip, u32 pcr_idx);
extern int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
struct tpm_digest *digests);
extern int tpm_send(struct tpm_chip *chip, void *cmd, size_t buflen);
@@ -440,6 +442,11 @@ static inline int tpm_pcr_read(struct tpm_chip *chip, int pcr_idx,
return -ENODEV;
}
+static inline int tpm_pcr_reset(struct tpm_chip *chip, int pcr_idx)
+{
+ return -ENODEV;
+}
+
static inline int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
struct tpm_digest *digests)
{
--
2.31.0
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