[PATCH v3 2/6] tpm: Store TPM buffer length

[PATCH v3 2/6] tpm: Store TPM buffer length

[Jarkko Sakkinen]

Both TPM commands and sized buffers (TPM2B) have a fixed size header, which
is followed by the body. Store TPM buffer length to a new field in the
struct tpm_buf.

The invariant here is that the length field must always contain the total
length of the buffer, i.e. the sum header and body length. The value must
then be mapped to the length representation of the buffer type, and this
correspondence must be maintained.

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
 drivers/char/tpm/tpm-buf.c                | 36 ++++++++++++++++-------
 drivers/char/tpm/tpm-interface.c          | 18 +++++++++---
 include/linux/tpm.h                       | 10 +++----
 security/keys/trusted-keys/trusted_tpm1.c |  8 ++---
 4 files changed, 49 insertions(+), 23 deletions(-)

diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
index 88ce1a5402de..8dc6b9db006b 100644
--- a/drivers/char/tpm/tpm-buf.c
+++ b/drivers/char/tpm/tpm-buf.c
@@ -18,6 +18,12 @@ int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal)
 }
 EXPORT_SYMBOL_GPL(tpm_buf_init);
 
+/**
+ * tpm_buf_reset() - Initialize a TPM command
+ * @buf:	A @tpm_buf
+ * @tag:	TPM_TAG_RQU_COMMAND, TPM2_ST_NO_SESSIONS or TPM2_ST_SESSIONS
+ * @ordinal:	A command ordinal
+ */
 void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal)
 {
 	struct tpm_header *head = (struct tpm_header *)buf->data;
@@ -25,6 +31,8 @@ void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal)
 	head->tag = cpu_to_be16(tag);
 	head->length = cpu_to_be32(sizeof(*head));
 	head->ordinal = cpu_to_be32(ordinal);
+
+	buf->length = sizeof(*head);
 }
 EXPORT_SYMBOL_GPL(tpm_buf_reset);
 
@@ -34,33 +42,41 @@ void tpm_buf_destroy(struct tpm_buf *buf)
 }
 EXPORT_SYMBOL_GPL(tpm_buf_destroy);
 
+/**
+ * tpm_buf_length() - Return the number of bytes consumed by the buffer
+ *
+ * Return: The number of bytes consumed by the buffer
+ */
 u32 tpm_buf_length(struct tpm_buf *buf)
 {
-	struct tpm_header *head = (struct tpm_header *)buf->data;
-
-	return be32_to_cpu(head->length);
+	return buf->length;
 }
 EXPORT_SYMBOL_GPL(tpm_buf_length);
 
-void tpm_buf_append(struct tpm_buf *buf,
-		    const unsigned char *new_data,
-		    unsigned int new_len)
+/**
+ * tpm_buf_append() - Append data to an initialized buffer
+ * @buf:	A &tpm_buf
+ * @new_data:	A data blob
+ * @new_length:	Size of the appended data
+ */
+
+void tpm_buf_append(struct tpm_buf *buf, const u8 *new_data, u16 new_length)
 {
 	struct tpm_header *head = (struct tpm_header *)buf->data;
-	u32 len = tpm_buf_length(buf);
 
 	/* Return silently if overflow has already happened. */
 	if (buf->flags & TPM_BUF_OVERFLOW)
 		return;
 
-	if ((len + new_len) > PAGE_SIZE) {
+	if ((buf->length + new_length) > PAGE_SIZE) {
 		WARN(1, "tpm_buf: overflow\n");
 		buf->flags |= TPM_BUF_OVERFLOW;
 		return;
 	}
 
-	memcpy(&buf->data[len], new_data, new_len);
-	head->length = cpu_to_be32(len + new_len);
+	memcpy(&buf->data[buf->length], new_data, new_length);
+	buf->length += new_length;
+	head->length = cpu_to_be32(buf->length);
 }
 EXPORT_SYMBOL_GPL(tpm_buf_append);
 
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 66b16d26eecc..492136214447 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -217,6 +217,9 @@ ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_buf *buf,
 	int err;
 	ssize_t len;
 
+	/* The recorded length is expected to match the command length: */
+	WARN_ON(buf->length != be32_to_cpu(header->length));
+
 	len = tpm_transmit(chip, buf->data, PAGE_SIZE);
 	if (len <  0)
 		return len;
@@ -232,6 +235,11 @@ ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_buf *buf,
 	if (len < min_rsp_body_length + TPM_HEADER_SIZE)
 		return -EFAULT;
 
+	buf->length = len;
+
+	/* The recorded length is expected to match the response length: */
+	WARN_ON(buf->length != be32_to_cpu(header->length));
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(tpm_transmit_cmd);
@@ -345,12 +353,12 @@ EXPORT_SYMBOL_GPL(tpm_pcr_extend);
 /**
  * tpm_send - send a TPM command
  * @chip:	a &struct tpm_chip instance, %NULL for the default chip
- * @cmd:	a TPM command buffer
- * @buflen:	the length of the TPM command buffer
+ * @data:	command blob
+ * @cmdlen:	length of the command
  *
  * Return: same as with tpm_transmit_cmd()
  */
-int tpm_send(struct tpm_chip *chip, void *cmd, size_t buflen)
+int tpm_send(struct tpm_chip *chip, void *data, size_t length)
 {
 	struct tpm_buf buf;
 	int rc;
@@ -359,7 +367,9 @@ int tpm_send(struct tpm_chip *chip, void *cmd, size_t buflen)
 	if (!chip)
 		return -ENODEV;
 
-	buf.data = cmd;
+	buf.flags = 0;
+	buf.length = length;
+	buf.data = data;
 	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to a send a command");
 
 	tpm_put_ops(chip);
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 60032c60994b..3cfe2aeb1d9a 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -307,7 +307,8 @@ enum tpm_buf_flags {
 };
 
 struct tpm_buf {
-	unsigned int flags;
+	u32 flags;
+	u16 length;
 	u8 *data;
 };
 
@@ -331,8 +332,7 @@ int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal);
 void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal);
 void tpm_buf_destroy(struct tpm_buf *buf);
 u32 tpm_buf_length(struct tpm_buf *buf);
-void tpm_buf_append(struct tpm_buf *buf, const unsigned char *new_data,
-		    unsigned int new_len);
+void tpm_buf_append(struct tpm_buf *buf, const u8 *new_data, u16 new_length);
 void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value);
 void tpm_buf_append_u16(struct tpm_buf *buf, const u16 value);
 void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value);
@@ -361,7 +361,7 @@ extern int tpm_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
 			struct tpm_digest *digest);
 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);
+int tpm_send(struct tpm_chip *chip, void *data, size_t length);
 extern int tpm_get_random(struct tpm_chip *chip, u8 *data, size_t max);
 extern struct tpm_chip *tpm_default_chip(void);
 void tpm2_flush_context(struct tpm_chip *chip, u32 handle);
@@ -382,7 +382,7 @@ static inline int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
 	return -ENODEV;
 }
 
-static inline int tpm_send(struct tpm_chip *chip, void *cmd, size_t buflen)
+static inline int tpm_send(struct tpm_chip *chip, void *data, size_t length)
 {
 	return -ENODEV;
 }
diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c
index aa108bea6739..7c1515014a5d 100644
--- a/security/keys/trusted-keys/trusted_tpm1.c
+++ b/security/keys/trusted-keys/trusted_tpm1.c
@@ -407,7 +407,7 @@ static int osap(struct tpm_buf *tb, struct osapsess *s,
 	tpm_buf_append_u32(tb, handle);
 	tpm_buf_append(tb, ononce, TPM_NONCE_SIZE);
 
-	ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
+	ret = trusted_tpm_send(tb->data, tb->length);
 	if (ret < 0)
 		return ret;
 
@@ -431,7 +431,7 @@ int oiap(struct tpm_buf *tb, uint32_t *handle, unsigned char *nonce)
 		return -ENODEV;
 
 	tpm_buf_reset(tb, TPM_TAG_RQU_COMMAND, TPM_ORD_OIAP);
-	ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
+	ret = trusted_tpm_send(tb->data, tb->length);
 	if (ret < 0)
 		return ret;
 
@@ -543,7 +543,7 @@ static int tpm_seal(struct tpm_buf *tb, uint16_t keytype,
 	tpm_buf_append_u8(tb, cont);
 	tpm_buf_append(tb, td->pubauth, SHA1_DIGEST_SIZE);
 
-	ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
+	ret = trusted_tpm_send(tb->data, tb->length);
 	if (ret < 0)
 		goto out;
 
@@ -634,7 +634,7 @@ static int tpm_unseal(struct tpm_buf *tb,
 	tpm_buf_append_u8(tb, cont);
 	tpm_buf_append(tb, authdata2, SHA1_DIGEST_SIZE);
 
-	ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
+	ret = trusted_tpm_send(tb->data, tb->length);
 	if (ret < 0) {
 		pr_info("authhmac failed (%d)\n", ret);
 		return ret;
-- 
2.42.0

Re: [PATCH v3 2/6] tpm: Store TPM buffer length

[Jerry Snitselaar]

Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>

Re: [PATCH v3 2/6] tpm: Store TPM buffer length

[Jarkko Sakkinen]

On Mon Nov 6, 2023 at 9:26 PM EET, Jerry Snitselaar wrote:
>
> Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>

Thanks.

BR, Jarkko

Re: [PATCH v3 2/6] tpm: Store TPM buffer length

[Jerry Snitselaar]

On Tue, Oct 24, 2023 at 04:15:20AM +0300, Jarkko Sakkinen wrote:
> Both TPM commands and sized buffers (TPM2B) have a fixed size header, which
> is followed by the body. Store TPM buffer length to a new field in the
> struct tpm_buf.
> 
> The invariant here is that the length field must always contain the total
> length of the buffer, i.e. the sum header and body length. The value must
> then be mapped to the length representation of the buffer type, and this
> correspondence must be maintained.
> 
> Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
> ---
>  drivers/char/tpm/tpm-buf.c                | 36 ++++++++++++++++-------
>  drivers/char/tpm/tpm-interface.c          | 18 +++++++++---
>  include/linux/tpm.h                       | 10 +++----
>  security/keys/trusted-keys/trusted_tpm1.c |  8 ++---
>  4 files changed, 49 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
> index 88ce1a5402de..8dc6b9db006b 100644
> --- a/drivers/char/tpm/tpm-buf.c
> +++ b/drivers/char/tpm/tpm-buf.c
> @@ -18,6 +18,12 @@ int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal)
>  }
>  EXPORT_SYMBOL_GPL(tpm_buf_init);
>  
> +/**
> + * tpm_buf_reset() - Initialize a TPM command
> + * @buf:	A @tpm_buf

One minor thing I meant to mention, did you intend this to be &tpm_buf like it
is for tpm_buf_append?

Regards,
Jerry

Re: [PATCH v3 2/6] tpm: Store TPM buffer length

[Jarkko Sakkinen]

On Mon Nov 6, 2023 at 9:36 PM EET, Jerry Snitselaar wrote:
> On Tue, Oct 24, 2023 at 04:15:20AM +0300, Jarkko Sakkinen wrote:
> > Both TPM commands and sized buffers (TPM2B) have a fixed size header, which
> > is followed by the body. Store TPM buffer length to a new field in the
> > struct tpm_buf.
> > 
> > The invariant here is that the length field must always contain the total
> > length of the buffer, i.e. the sum header and body length. The value must
> > then be mapped to the length representation of the buffer type, and this
> > correspondence must be maintained.
> > 
> > Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
> > ---
> >  drivers/char/tpm/tpm-buf.c                | 36 ++++++++++++++++-------
> >  drivers/char/tpm/tpm-interface.c          | 18 +++++++++---
> >  include/linux/tpm.h                       | 10 +++----
> >  security/keys/trusted-keys/trusted_tpm1.c |  8 ++---
> >  4 files changed, 49 insertions(+), 23 deletions(-)
> > 
> > diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
> > index 88ce1a5402de..8dc6b9db006b 100644
> > --- a/drivers/char/tpm/tpm-buf.c
> > +++ b/drivers/char/tpm/tpm-buf.c
> > @@ -18,6 +18,12 @@ int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal)
> >  }
> >  EXPORT_SYMBOL_GPL(tpm_buf_init);
> >  
> > +/**
> > + * tpm_buf_reset() - Initialize a TPM command
> > + * @buf:	A @tpm_buf
>
> One minor thing I meant to mention, did you intend this to be &tpm_buf like it
> is for tpm_buf_append?

Yep, thanks. I'll change it to &tpm_buf.

BR, Jarkko

[PATCH v3 3/6] tpm: Detach tpm_buf_reset() from tpm_buf_init()

[Jarkko Sakkinen]

In order to use tpm_buf_init() for other buffer types, detach
tpm_buf_reset() from tpm_buf_init().

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
 drivers/char/tpm/tpm-buf.c                | 15 ++++++++--
 drivers/char/tpm/tpm-sysfs.c              |  3 +-
 drivers/char/tpm/tpm1-cmd.c               | 26 +++++++++++-----
 drivers/char/tpm/tpm2-cmd.c               | 36 ++++++++++++++++-------
 drivers/char/tpm/tpm2-space.c             |  7 +++--
 drivers/char/tpm/tpm_vtpm_proxy.c         | 13 ++++----
 include/linux/tpm.h                       |  2 +-
 security/keys/trusted-keys/trusted_tpm1.c |  4 +--
 security/keys/trusted-keys/trusted_tpm2.c |  9 ++++--
 9 files changed, 80 insertions(+), 35 deletions(-)

diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
index 8dc6b9db006b..fa9a4c51157a 100644
--- a/drivers/char/tpm/tpm-buf.c
+++ b/drivers/char/tpm/tpm-buf.c
@@ -6,14 +6,25 @@
 #include <linux/module.h>
 #include <linux/tpm.h>
 
-int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal)
+/**
+ * tpm_buf_init() - Initialize from the heap
+ * @buf:	A @tpm_buf
+ *
+ * Initialize all structure fields to zero, allocate a page from the heap, and
+ * zero the bytes that the buffer headers will consume.
+ *
+ * Return: 0 or -ENOMEM
+ */
+int tpm_buf_init(struct tpm_buf *buf)
 {
 	buf->data = (u8 *)__get_free_page(GFP_KERNEL);
 	if (!buf->data)
 		return -ENOMEM;
 
 	buf->flags = 0;
-	tpm_buf_reset(buf, tag, ordinal);
+	buf->length = TPM_HEADER_SIZE;
+	memset(buf->data, 0, TPM_HEADER_SIZE);
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(tpm_buf_init);
diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
index 54c71473aa29..557e7f86d98d 100644
--- a/drivers/char/tpm/tpm-sysfs.c
+++ b/drivers/char/tpm/tpm-sysfs.c
@@ -44,9 +44,10 @@ static ssize_t pubek_show(struct device *dev, struct device_attribute *attr,
 	if (tpm_try_get_ops(chip))
 		return 0;
 
-	if (tpm_buf_init(&tpm_buf, TPM_TAG_RQU_COMMAND, TPM_ORD_READPUBEK))
+	if (tpm_buf_init(&tpm_buf))
 		goto out_ops;
 
+	tpm_buf_reset(&tpm_buf, TPM_TAG_RQU_COMMAND, TPM_ORD_READPUBEK);
 	tpm_buf_append(&tpm_buf, anti_replay, sizeof(anti_replay));
 
 	if (tpm_transmit_cmd(chip, &tpm_buf, READ_PUBEK_RESULT_MIN_BODY_SIZE,
diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index cf64c7385105..28fea4e2daaf 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -328,10 +328,11 @@ static int tpm1_startup(struct tpm_chip *chip)
 
 	dev_info(&chip->dev, "starting up the TPM manually\n");
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_STARTUP);
+	rc = tpm_buf_init(&buf);
 	if (rc < 0)
 		return rc;
 
+	tpm_buf_reset(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_STARTUP);
 	tpm_buf_append_u16(&buf, TPM_ST_CLEAR);
 
 	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to start the TPM");
@@ -466,10 +467,11 @@ int tpm1_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash,
 	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_PCR_EXTEND);
+	rc = tpm_buf_init(&buf);
 	if (rc)
 		return rc;
 
+	tpm_buf_reset(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_PCR_EXTEND);
 	tpm_buf_append_u32(&buf, pcr_idx);
 	tpm_buf_append(&buf, hash, TPM_DIGEST_SIZE);
 
@@ -485,10 +487,12 @@ ssize_t tpm1_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap,
 	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_CAP);
+	rc = tpm_buf_init(&buf);
 	if (rc)
 		return rc;
 
+	tpm_buf_reset(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_CAP);
+
 	if (subcap_id == TPM_CAP_VERSION_1_1 ||
 	    subcap_id == TPM_CAP_VERSION_1_2) {
 		tpm_buf_append_u32(&buf, subcap_id);
@@ -537,10 +541,12 @@ int tpm1_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
 	u32 recd;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_RANDOM);
+	rc = tpm_buf_init(&buf);
 	if (rc)
 		return rc;
 
+	tpm_buf_reset(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_RANDOM);
+
 	do {
 		tpm_buf_append_u32(&buf, num_bytes);
 
@@ -586,10 +592,11 @@ int tpm1_pcr_read(struct tpm_chip *chip, u32 pcr_idx, u8 *res_buf)
 	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_PCRREAD);
+	rc = tpm_buf_init(&buf);
 	if (rc)
 		return rc;
 
+	tpm_buf_reset(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_PCRREAD);
 	tpm_buf_append_u32(&buf, pcr_idx);
 
 	rc = tpm_transmit_cmd(chip, &buf, TPM_DIGEST_SIZE,
@@ -622,10 +629,12 @@ static int tpm1_continue_selftest(struct tpm_chip *chip)
 	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_CONTINUE_SELFTEST);
+	rc = tpm_buf_init(&buf);
 	if (rc)
 		return rc;
 
+	tpm_buf_reset(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_CONTINUE_SELFTEST);
+
 	rc = tpm_transmit_cmd(chip, &buf, 0, "continue selftest");
 	tpm_buf_destroy(&buf);
 	return rc;
@@ -752,9 +761,12 @@ int tpm1_pm_suspend(struct tpm_chip *chip, u32 tpm_suspend_pcr)
 		rc = tpm1_pcr_extend(chip, tpm_suspend_pcr, dummy_hash,
 				     "extending dummy pcr before suspend");
 
-	rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_SAVESTATE);
+	rc = tpm_buf_init(&buf);
 	if (rc)
 		return rc;
+
+	tpm_buf_reset(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_SAVESTATE);
+
 	/* now do the actual savestate */
 	for (try = 0; try < TPM_RETRY; try++) {
 		rc = tpm_transmit_cmd(chip, &buf, 0, NULL);
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 93545be190a5..94dacbf74e0d 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -183,10 +183,12 @@ int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
 		expected_digest_size = chip->allocated_banks[i].digest_size;
 	}
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_PCR_READ);
+	rc = tpm_buf_init(&buf);
 	if (rc)
 		return rc;
 
+	tpm_buf_reset(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_PCR_READ);
+
 	pcr_select[pcr_idx >> 3] = 1 << (pcr_idx & 0x7);
 
 	tpm_buf_append_u32(&buf, 1);
@@ -240,10 +242,11 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
 	int rc;
 	int i;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND);
+	rc = tpm_buf_init(&buf);
 	if (rc)
 		return rc;
 
+	tpm_buf_reset(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND);
 	tpm_buf_append_u32(&buf, pcr_idx);
 
 	auth_area.handle = cpu_to_be32(TPM2_RS_PW);
@@ -299,7 +302,7 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
 	if (!num_bytes || max > TPM_MAX_RNG_DATA)
 		return -EINVAL;
 
-	err = tpm_buf_init(&buf, 0, 0);
+	err = tpm_buf_init(&buf);
 	if (err)
 		return err;
 
@@ -350,13 +353,14 @@ void tpm2_flush_context(struct tpm_chip *chip, u32 handle)
 	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_FLUSH_CONTEXT);
+	rc = tpm_buf_init(&buf);
 	if (rc) {
 		dev_warn(&chip->dev, "0x%08x was not flushed, out of memory\n",
 			 handle);
 		return;
 	}
 
+	tpm_buf_reset(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_FLUSH_CONTEXT);
 	tpm_buf_append_u32(&buf, handle);
 
 	tpm_transmit_cmd(chip, &buf, 0, "flushing context");
@@ -390,9 +394,11 @@ ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id,  u32 *value,
 	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
+	rc = tpm_buf_init(&buf);
 	if (rc)
 		return rc;
+
+	tpm_buf_reset(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
 	tpm_buf_append_u32(&buf, TPM2_CAP_TPM_PROPERTIES);
 	tpm_buf_append_u32(&buf, property_id);
 	tpm_buf_append_u32(&buf, 1);
@@ -431,9 +437,11 @@ void tpm2_shutdown(struct tpm_chip *chip, u16 shutdown_type)
 	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_SHUTDOWN);
+	rc = tpm_buf_init(&buf);
 	if (rc)
 		return;
+
+	tpm_buf_reset(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_SHUTDOWN);
 	tpm_buf_append_u16(&buf, shutdown_type);
 	tpm_transmit_cmd(chip, &buf, 0, "stopping the TPM");
 	tpm_buf_destroy(&buf);
@@ -459,10 +467,11 @@ static int tpm2_do_selftest(struct tpm_chip *chip)
 	int rc;
 
 	for (full = 0; full < 2; full++) {
-		rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_SELF_TEST);
+		rc = tpm_buf_init(&buf);
 		if (rc)
 			return rc;
 
+		tpm_buf_reset(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_SELF_TEST);
 		tpm_buf_append_u8(&buf, full);
 		rc = tpm_transmit_cmd(chip, &buf, 0,
 				      "attempting the self test");
@@ -495,9 +504,11 @@ int tpm2_probe(struct tpm_chip *chip)
 	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
+	rc = tpm_buf_init(&buf);
 	if (rc)
 		return rc;
+
+	tpm_buf_reset(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
 	tpm_buf_append_u32(&buf, TPM2_CAP_TPM_PROPERTIES);
 	tpm_buf_append_u32(&buf, TPM_PT_TOTAL_COMMANDS);
 	tpm_buf_append_u32(&buf, 1);
@@ -560,10 +571,11 @@ ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 	int rc;
 	int i = 0;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
+	rc = tpm_buf_init(&buf);
 	if (rc)
 		return rc;
 
+	tpm_buf_reset(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
 	tpm_buf_append_u32(&buf, TPM2_CAP_PCRS);
 	tpm_buf_append_u32(&buf, 0);
 	tpm_buf_append_u32(&buf, 1);
@@ -649,10 +661,11 @@ int tpm2_get_cc_attrs_tbl(struct tpm_chip *chip)
 		goto out;
 	}
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
+	rc = tpm_buf_init(&buf);
 	if (rc)
 		goto out;
 
+	tpm_buf_reset(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_GET_CAPABILITY);
 	tpm_buf_append_u32(&buf, TPM2_CAP_COMMANDS);
 	tpm_buf_append_u32(&buf, TPM2_CC_FIRST);
 	tpm_buf_append_u32(&buf, nr_commands);
@@ -711,10 +724,11 @@ static int tpm2_startup(struct tpm_chip *chip)
 
 	dev_info(&chip->dev, "starting up the TPM manually\n");
 
-	rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_STARTUP);
+	rc = tpm_buf_init(&buf);
 	if (rc < 0)
 		return rc;
 
+	tpm_buf_reset(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_STARTUP);
 	tpm_buf_append_u16(&buf, TPM2_SU_CLEAR);
 	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to start the TPM");
 	tpm_buf_destroy(&buf);
diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c
index 363afdd4d1d3..43584b4176d6 100644
--- a/drivers/char/tpm/tpm2-space.c
+++ b/drivers/char/tpm/tpm2-space.c
@@ -76,10 +76,12 @@ static int tpm2_load_context(struct tpm_chip *chip, u8 *buf,
 	unsigned int body_size;
 	int rc;
 
-	rc = tpm_buf_init(&tbuf, TPM2_ST_NO_SESSIONS, TPM2_CC_CONTEXT_LOAD);
+	rc = tpm_buf_init(&tbuf);
 	if (rc)
 		return rc;
 
+	tpm_buf_reset(&tbuf, TPM2_ST_NO_SESSIONS, TPM2_CC_CONTEXT_LOAD);
+
 	ctx = (struct tpm2_context *)&buf[*offset];
 	body_size = sizeof(*ctx) + be16_to_cpu(ctx->blob_size);
 	tpm_buf_append(&tbuf, &buf[*offset], body_size);
@@ -126,10 +128,11 @@ static int tpm2_save_context(struct tpm_chip *chip, u32 handle, u8 *buf,
 	unsigned int body_size;
 	int rc;
 
-	rc = tpm_buf_init(&tbuf, TPM2_ST_NO_SESSIONS, TPM2_CC_CONTEXT_SAVE);
+	rc = tpm_buf_init(&tbuf);
 	if (rc)
 		return rc;
 
+	tpm_buf_reset(&tbuf, TPM2_ST_NO_SESSIONS, TPM2_CC_CONTEXT_SAVE);
 	tpm_buf_append_u32(&tbuf, handle);
 
 	rc = tpm_transmit_cmd(chip, &tbuf, 0, NULL);
diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c b/drivers/char/tpm/tpm_vtpm_proxy.c
index 30e953988cab..b2b9a15a4a59 100644
--- a/drivers/char/tpm/tpm_vtpm_proxy.c
+++ b/drivers/char/tpm/tpm_vtpm_proxy.c
@@ -399,14 +399,15 @@ static int vtpm_proxy_request_locality(struct tpm_chip *chip, int locality)
 	const struct tpm_header *header;
 	struct proxy_dev *proxy_dev = dev_get_drvdata(&chip->dev);
 
-	if (chip->flags & TPM_CHIP_FLAG_TPM2)
-		rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS,
-				  TPM2_CC_SET_LOCALITY);
-	else
-		rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND,
-				  TPM_ORD_SET_LOCALITY);
+	rc = tpm_buf_init(&buf);
 	if (rc)
 		return rc;
+
+	if (chip->flags & TPM_CHIP_FLAG_TPM2)
+		tpm_buf_reset(&buf, TPM2_ST_SESSIONS, TPM2_CC_SET_LOCALITY);
+	else
+		tpm_buf_reset(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_SET_LOCALITY);
+
 	tpm_buf_append_u8(&buf, locality);
 
 	proxy_dev->state |= STATE_DRIVER_COMMAND;
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 3cfe2aeb1d9a..c355597351c6 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -328,7 +328,7 @@ struct tpm2_hash {
 };
 
 
-int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal);
+int tpm_buf_init(struct tpm_buf *buf);
 void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal);
 void tpm_buf_destroy(struct tpm_buf *buf);
 u32 tpm_buf_length(struct tpm_buf *buf);
diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c
index 7c1515014a5d..fcf0eef79ba0 100644
--- a/security/keys/trusted-keys/trusted_tpm1.c
+++ b/security/keys/trusted-keys/trusted_tpm1.c
@@ -664,7 +664,7 @@ static int key_seal(struct trusted_key_payload *p,
 	struct tpm_buf tb;
 	int ret;
 
-	ret = tpm_buf_init(&tb, 0, 0);
+	ret = tpm_buf_init(&tb);
 	if (ret)
 		return ret;
 
@@ -690,7 +690,7 @@ static int key_unseal(struct trusted_key_payload *p,
 	struct tpm_buf tb;
 	int ret;
 
-	ret = tpm_buf_init(&tb, 0, 0);
+	ret = tpm_buf_init(&tb);
 	if (ret)
 		return ret;
 
diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index bc700f85f80b..c54659d06dcb 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -252,12 +252,13 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 	if (rc)
 		return rc;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE);
+	rc = tpm_buf_init(&buf);
 	if (rc) {
 		tpm_put_ops(chip);
 		return rc;
 	}
 
+	tpm_buf_reset(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE);
 	tpm_buf_append_u32(&buf, options->keyhandle);
 	tpm2_buf_append_auth(&buf, TPM2_RS_PW,
 			     NULL /* nonce */, 0,
@@ -409,10 +410,11 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 	if (blob_len > payload->blob_len)
 		return -E2BIG;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD);
+	rc = tpm_buf_init(&buf);
 	if (rc)
 		return rc;
 
+	tpm_buf_reset(&buf, TPM2_ST_SESSIONS, TPM2_CC_LOAD);
 	tpm_buf_append_u32(&buf, options->keyhandle);
 	tpm2_buf_append_auth(&buf, TPM2_RS_PW,
 			     NULL /* nonce */, 0,
@@ -465,10 +467,11 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 	u8 *data;
 	int rc;
 
-	rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL);
+	rc = tpm_buf_init(&buf);
 	if (rc)
 		return rc;
 
+	tpm_buf_reset(&buf, TPM2_ST_SESSIONS, TPM2_CC_UNSEAL);
 	tpm_buf_append_u32(&buf, blob_handle);
 	tpm2_buf_append_auth(&buf,
 			     options->policyhandle ?
-- 
2.42.0

Re: [PATCH v3 3/6] tpm: Detach tpm_buf_reset() from tpm_buf_init()

[Jerry Snitselaar]

Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>

Re: [PATCH v3 3/6] tpm: Detach tpm_buf_reset() from tpm_buf_init()

[Jarkko Sakkinen]

On Mon Nov 6, 2023 at 9:31 PM EET, Jerry Snitselaar wrote:
> Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>

Thanks.

BR, Jarkko

[PATCH v3 4/6] tpm: Support TPM2 sized buffers (TPM2B)

[Jarkko Sakkinen]

Add boolean parameters @alloc and @sized to tpm_buf_init():

* If @alloc is set to false, buf->data is assumed to be pre-feeded and
  owned by the caller.
* If @sized is set to true, the buffer represents a sized buffer
  (TPM2B).

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
 drivers/char/tpm/tpm-buf.c                | 32 ++++++++++++++++-------
 drivers/char/tpm/tpm-sysfs.c              |  2 +-
 drivers/char/tpm/tpm1-cmd.c               | 14 +++++-----
 drivers/char/tpm/tpm2-cmd.c               | 22 ++++++++--------
 drivers/char/tpm/tpm2-space.c             |  4 +--
 drivers/char/tpm/tpm_vtpm_proxy.c         |  2 +-
 include/linux/tpm.h                       |  3 ++-
 security/keys/trusted-keys/trusted_tpm1.c |  4 +--
 security/keys/trusted-keys/trusted_tpm2.c |  6 ++---
 9 files changed, 51 insertions(+), 38 deletions(-)

diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
index fa9a4c51157a..f1d92d7e758d 100644
--- a/drivers/char/tpm/tpm-buf.c
+++ b/drivers/char/tpm/tpm-buf.c
@@ -7,22 +7,32 @@
 #include <linux/tpm.h>
 
 /**
- * tpm_buf_init() - Initialize from the heap
+ * tpm_buf_init() - Initialize a TPM buffer
  * @buf:	A @tpm_buf
+ * @sized:	Represent a sized buffer (TPM2B)
+ * @alloc:	Allocate from the heap
  *
  * Initialize all structure fields to zero, allocate a page from the heap, and
  * zero the bytes that the buffer headers will consume.
  *
  * Return: 0 or -ENOMEM
  */
-int tpm_buf_init(struct tpm_buf *buf)
+int tpm_buf_init(struct tpm_buf *buf, bool alloc, bool sized)
 {
-	buf->data = (u8 *)__get_free_page(GFP_KERNEL);
-	if (!buf->data)
-		return -ENOMEM;
+	if (alloc) {
+		buf->data = (u8 *)__get_free_page(GFP_KERNEL);
+		if (!buf->data)
+			return -ENOMEM;
+	}
+
+	if (sized) {
+		buf->flags = TPM_BUF_SIZED;
+		buf->length = 2;
+	} else {
+		buf->flags = 0;
+		buf->length = TPM_HEADER_SIZE;
+	}
 
-	buf->flags = 0;
-	buf->length = TPM_HEADER_SIZE;
 	memset(buf->data, 0, TPM_HEADER_SIZE);
 
 	return 0;
@@ -73,8 +83,6 @@ EXPORT_SYMBOL_GPL(tpm_buf_length);
 
 void tpm_buf_append(struct tpm_buf *buf, const u8 *new_data, u16 new_length)
 {
-	struct tpm_header *head = (struct tpm_header *)buf->data;
-
 	/* Return silently if overflow has already happened. */
 	if (buf->flags & TPM_BUF_OVERFLOW)
 		return;
@@ -87,7 +95,11 @@ void tpm_buf_append(struct tpm_buf *buf, const u8 *new_data, u16 new_length)
 
 	memcpy(&buf->data[buf->length], new_data, new_length);
 	buf->length += new_length;
-	head->length = cpu_to_be32(buf->length);
+
+	if (buf->flags & TPM_BUF_SIZED)
+		((__be16 *)buf->data)[0] = cpu_to_be16(buf->length - 2);
+	else
+		((struct tpm_header *)buf->data)->length = cpu_to_be32(buf->length);
 }
 EXPORT_SYMBOL_GPL(tpm_buf_append);
 
diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
index 557e7f86d98d..047a7064039e 100644
--- a/drivers/char/tpm/tpm-sysfs.c
+++ b/drivers/char/tpm/tpm-sysfs.c
@@ -44,7 +44,7 @@ static ssize_t pubek_show(struct device *dev, struct device_attribute *attr,
 	if (tpm_try_get_ops(chip))
 		return 0;
 
-	if (tpm_buf_init(&tpm_buf))
+	if (tpm_buf_init(&tpm_buf, true, false))
 		goto out_ops;
 
 	tpm_buf_reset(&tpm_buf, TPM_TAG_RQU_COMMAND, TPM_ORD_READPUBEK);
diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index 28fea4e2daaf..396694018590 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -328,7 +328,7 @@ static int tpm1_startup(struct tpm_chip *chip)
 
 	dev_info(&chip->dev, "starting up the TPM manually\n");
 
-	rc = tpm_buf_init(&buf);
+	rc = tpm_buf_init(&buf, true, false);
 	if (rc < 0)
 		return rc;
 
@@ -467,7 +467,7 @@ int tpm1_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash,
 	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf);
+	rc = tpm_buf_init(&buf, true, false);
 	if (rc)
 		return rc;
 
@@ -487,7 +487,7 @@ ssize_t tpm1_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap,
 	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf);
+	rc = tpm_buf_init(&buf, true, false);
 	if (rc)
 		return rc;
 
@@ -541,7 +541,7 @@ int tpm1_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
 	u32 recd;
 	int rc;
 
-	rc = tpm_buf_init(&buf);
+	rc = tpm_buf_init(&buf, true, false);
 	if (rc)
 		return rc;
 
@@ -592,7 +592,7 @@ int tpm1_pcr_read(struct tpm_chip *chip, u32 pcr_idx, u8 *res_buf)
 	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf);
+	rc = tpm_buf_init(&buf, true, false);
 	if (rc)
 		return rc;
 
@@ -629,7 +629,7 @@ static int tpm1_continue_selftest(struct tpm_chip *chip)
 	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf);
+	rc = tpm_buf_init(&buf, true, false);
 	if (rc)
 		return rc;
 
@@ -761,7 +761,7 @@ int tpm1_pm_suspend(struct tpm_chip *chip, u32 tpm_suspend_pcr)
 		rc = tpm1_pcr_extend(chip, tpm_suspend_pcr, dummy_hash,
 				     "extending dummy pcr before suspend");
 
-	rc = tpm_buf_init(&buf);
+	rc = tpm_buf_init(&buf, true, false);
 	if (rc)
 		return rc;
 
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 94dacbf74e0d..1d3e0833641d 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -183,7 +183,7 @@ int tpm2_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
 		expected_digest_size = chip->allocated_banks[i].digest_size;
 	}
 
-	rc = tpm_buf_init(&buf);
+	rc = tpm_buf_init(&buf, true, false);
 	if (rc)
 		return rc;
 
@@ -242,7 +242,7 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
 	int rc;
 	int i;
 
-	rc = tpm_buf_init(&buf);
+	rc = tpm_buf_init(&buf, true, false);
 	if (rc)
 		return rc;
 
@@ -302,7 +302,7 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max)
 	if (!num_bytes || max > TPM_MAX_RNG_DATA)
 		return -EINVAL;
 
-	err = tpm_buf_init(&buf);
+	err = tpm_buf_init(&buf, true, false);
 	if (err)
 		return err;
 
@@ -353,7 +353,7 @@ void tpm2_flush_context(struct tpm_chip *chip, u32 handle)
 	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf);
+	rc = tpm_buf_init(&buf, true, false);
 	if (rc) {
 		dev_warn(&chip->dev, "0x%08x was not flushed, out of memory\n",
 			 handle);
@@ -394,7 +394,7 @@ ssize_t tpm2_get_tpm_pt(struct tpm_chip *chip, u32 property_id,  u32 *value,
 	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf);
+	rc = tpm_buf_init(&buf, true, false);
 	if (rc)
 		return rc;
 
@@ -437,7 +437,7 @@ void tpm2_shutdown(struct tpm_chip *chip, u16 shutdown_type)
 	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf);
+	rc = tpm_buf_init(&buf, true, false);
 	if (rc)
 		return;
 
@@ -467,7 +467,7 @@ static int tpm2_do_selftest(struct tpm_chip *chip)
 	int rc;
 
 	for (full = 0; full < 2; full++) {
-		rc = tpm_buf_init(&buf);
+		rc = tpm_buf_init(&buf, true, false);
 		if (rc)
 			return rc;
 
@@ -504,7 +504,7 @@ int tpm2_probe(struct tpm_chip *chip)
 	struct tpm_buf buf;
 	int rc;
 
-	rc = tpm_buf_init(&buf);
+	rc = tpm_buf_init(&buf, true, false);
 	if (rc)
 		return rc;
 
@@ -571,7 +571,7 @@ ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
 	int rc;
 	int i = 0;
 
-	rc = tpm_buf_init(&buf);
+	rc = tpm_buf_init(&buf, true, false);
 	if (rc)
 		return rc;
 
@@ -661,7 +661,7 @@ int tpm2_get_cc_attrs_tbl(struct tpm_chip *chip)
 		goto out;
 	}
 
-	rc = tpm_buf_init(&buf);
+	rc = tpm_buf_init(&buf, true, false);
 	if (rc)
 		goto out;
 
@@ -724,7 +724,7 @@ static int tpm2_startup(struct tpm_chip *chip)
 
 	dev_info(&chip->dev, "starting up the TPM manually\n");
 
-	rc = tpm_buf_init(&buf);
+	rc = tpm_buf_init(&buf, true, false);
 	if (rc < 0)
 		return rc;
 
diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c
index 43584b4176d6..ab2a863baffb 100644
--- a/drivers/char/tpm/tpm2-space.c
+++ b/drivers/char/tpm/tpm2-space.c
@@ -76,7 +76,7 @@ static int tpm2_load_context(struct tpm_chip *chip, u8 *buf,
 	unsigned int body_size;
 	int rc;
 
-	rc = tpm_buf_init(&tbuf);
+	rc = tpm_buf_init(&tbuf, true, false);
 	if (rc)
 		return rc;
 
@@ -128,7 +128,7 @@ static int tpm2_save_context(struct tpm_chip *chip, u32 handle, u8 *buf,
 	unsigned int body_size;
 	int rc;
 
-	rc = tpm_buf_init(&tbuf);
+	rc = tpm_buf_init(&tbuf, true, false);
 	if (rc)
 		return rc;
 
diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c b/drivers/char/tpm/tpm_vtpm_proxy.c
index b2b9a15a4a59..52325abd395d 100644
--- a/drivers/char/tpm/tpm_vtpm_proxy.c
+++ b/drivers/char/tpm/tpm_vtpm_proxy.c
@@ -399,7 +399,7 @@ static int vtpm_proxy_request_locality(struct tpm_chip *chip, int locality)
 	const struct tpm_header *header;
 	struct proxy_dev *proxy_dev = dev_get_drvdata(&chip->dev);
 
-	rc = tpm_buf_init(&buf);
+	rc = tpm_buf_init(&buf, true, false);
 	if (rc)
 		return rc;
 
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index c355597351c6..687b5173bdab 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -304,6 +304,7 @@ struct tpm_header {
 
 enum tpm_buf_flags {
 	TPM_BUF_OVERFLOW	= BIT(0),
+	TPM_BUF_SIZED		= BIT(1),
 };
 
 struct tpm_buf {
@@ -328,7 +329,7 @@ struct tpm2_hash {
 };
 
 
-int tpm_buf_init(struct tpm_buf *buf);
+int tpm_buf_init(struct tpm_buf *buf, bool alloc, bool sized);
 void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal);
 void tpm_buf_destroy(struct tpm_buf *buf);
 u32 tpm_buf_length(struct tpm_buf *buf);
diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c
index fcf0eef79ba0..ed5dc3b45d52 100644
--- a/security/keys/trusted-keys/trusted_tpm1.c
+++ b/security/keys/trusted-keys/trusted_tpm1.c
@@ -664,7 +664,7 @@ static int key_seal(struct trusted_key_payload *p,
 	struct tpm_buf tb;
 	int ret;
 
-	ret = tpm_buf_init(&tb);
+	ret = tpm_buf_init(&tb, true, false);
 	if (ret)
 		return ret;
 
@@ -690,7 +690,7 @@ static int key_unseal(struct trusted_key_payload *p,
 	struct tpm_buf tb;
 	int ret;
 
-	ret = tpm_buf_init(&tb);
+	ret = tpm_buf_init(&tb, true, false);
 	if (ret)
 		return ret;
 
diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index c54659d06dcb..c41f30770138 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -252,7 +252,7 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 	if (rc)
 		return rc;
 
-	rc = tpm_buf_init(&buf);
+	rc = tpm_buf_init(&buf, true, false);
 	if (rc) {
 		tpm_put_ops(chip);
 		return rc;
@@ -410,7 +410,7 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 	if (blob_len > payload->blob_len)
 		return -E2BIG;
 
-	rc = tpm_buf_init(&buf);
+	rc = tpm_buf_init(&buf, true, false);
 	if (rc)
 		return rc;
 
@@ -467,7 +467,7 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 	u8 *data;
 	int rc;
 
-	rc = tpm_buf_init(&buf);
+	rc = tpm_buf_init(&buf, true, false);
 	if (rc)
 		return rc;
 
-- 
2.42.0

Re: [PATCH v3 4/6] tpm: Support TPM2 sized buffers (TPM2B)

[Jarkko Sakkinen]

On Fri, 2023-10-27 at 08:32 -0400, James Bottomley wrote:
> On Tue, 2023-10-24 at 04:15 +0300, Jarkko Sakkinen wrote:
> > +++ b/drivers/char/tpm/tpm-buf.c
> > @@ -7,22 +7,32 @@
> >  #include <linux/tpm.h>
> >  
> >  /**
> > - * tpm_buf_init() - Initialize from the heap
> > + * tpm_buf_init() - Initialize a TPM buffer
> >   * @buf:       A @tpm_buf
> > + * @sized:     Represent a sized buffer (TPM2B)
> > + * @alloc:     Allocate from the heap
> >   *
> >   * Initialize all structure fields to zero, allocate a page from the
> > heap, and
> >   * zero the bytes that the buffer headers will consume.
> >   *
> >   * Return: 0 or -ENOMEM
> >   */
> > -int tpm_buf_init(struct tpm_buf *buf)
> > +int tpm_buf_init(struct tpm_buf *buf, bool alloc, bool sized)
> 
> I think it creates a phenomenally confusing interface to use multiple
> booleans because, unlike flags, it's not self describing at point of
> use.  The confusion is enormously heightened here by having the doc
> book arguments be the reverse of the actual function prototype (I just
> tripped over this).
> 
> The alloc flag is particularly counter intuitive: if you pass in an
> allocated buffer, you expect to be responsible for freeing it again,
> but that's not how you use it; you really use it like a reset not an
> alloc, which looks odd because you already created a separate
> tpm_buf_reset function which can't be used in this case.
> 
> Why not replace the alloc flags with two reset functions: one for TPM2B
> buffers and one for command buffers?
> 
> James

Or you can make that as internal (__tpm_buf_init()) and add two
wrappers.

BR, Jarkko

Re: [PATCH v3 4/6] tpm: Support TPM2 sized buffers (TPM2B)

[Jerry Snitselaar]

On Tue, Oct 24, 2023 at 04:15:22AM +0300, Jarkko Sakkinen wrote:
> Add boolean parameters @alloc and @sized to tpm_buf_init():
> 
> * If @alloc is set to false, buf->data is assumed to be pre-feeded and
>   owned by the caller.
> * If @sized is set to true, the buffer represents a sized buffer
>   (TPM2B).
> 
> Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
> ---
>  drivers/char/tpm/tpm-buf.c                | 32 ++++++++++++++++-------
>  drivers/char/tpm/tpm-sysfs.c              |  2 +-
>  drivers/char/tpm/tpm1-cmd.c               | 14 +++++-----
>  drivers/char/tpm/tpm2-cmd.c               | 22 ++++++++--------
>  drivers/char/tpm/tpm2-space.c             |  4 +--
>  drivers/char/tpm/tpm_vtpm_proxy.c         |  2 +-
>  include/linux/tpm.h                       |  3 ++-
>  security/keys/trusted-keys/trusted_tpm1.c |  4 +--
>  security/keys/trusted-keys/trusted_tpm2.c |  6 ++---
>  9 files changed, 51 insertions(+), 38 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
> index fa9a4c51157a..f1d92d7e758d 100644
> --- a/drivers/char/tpm/tpm-buf.c
> +++ b/drivers/char/tpm/tpm-buf.c
> @@ -7,22 +7,32 @@
>  #include <linux/tpm.h>
>  
>  /**
> - * tpm_buf_init() - Initialize from the heap
> + * tpm_buf_init() - Initialize a TPM buffer
>   * @buf:	A @tpm_buf
> + * @sized:	Represent a sized buffer (TPM2B)
> + * @alloc:	Allocate from the heap
>   *
>   * Initialize all structure fields to zero, allocate a page from the heap, and

Depending on what the decision ends up being on the bools, flags,
separate functions, or wrappers possibly an "if needed" should be
tacked on to the end of "allocate a page from the heap" here.


Flags would be better when coming across calls to the routine in the
code than the bools, but I think switching to wrappers around
a __tpm_buf_init for the different types would be good.


>   * zero the bytes that the buffer headers will consume.
>   *

Re: [PATCH v3 4/6] tpm: Support TPM2 sized buffers (TPM2B)

[Jarkko Sakkinen]

On Tue Nov 7, 2023 at 7:20 PM EET, Jerry Snitselaar wrote:
> On Tue, Oct 24, 2023 at 04:15:22AM +0300, Jarkko Sakkinen wrote:
> > Add boolean parameters @alloc and @sized to tpm_buf_init():
> > 
> > * If @alloc is set to false, buf->data is assumed to be pre-feeded and
> >   owned by the caller.
> > * If @sized is set to true, the buffer represents a sized buffer
> >   (TPM2B).
> > 
> > Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
> > ---
> >  drivers/char/tpm/tpm-buf.c                | 32 ++++++++++++++++-------
> >  drivers/char/tpm/tpm-sysfs.c              |  2 +-
> >  drivers/char/tpm/tpm1-cmd.c               | 14 +++++-----
> >  drivers/char/tpm/tpm2-cmd.c               | 22 ++++++++--------
> >  drivers/char/tpm/tpm2-space.c             |  4 +--
> >  drivers/char/tpm/tpm_vtpm_proxy.c         |  2 +-
> >  include/linux/tpm.h                       |  3 ++-
> >  security/keys/trusted-keys/trusted_tpm1.c |  4 +--
> >  security/keys/trusted-keys/trusted_tpm2.c |  6 ++---
> >  9 files changed, 51 insertions(+), 38 deletions(-)
> > 
> > diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
> > index fa9a4c51157a..f1d92d7e758d 100644
> > --- a/drivers/char/tpm/tpm-buf.c
> > +++ b/drivers/char/tpm/tpm-buf.c
> > @@ -7,22 +7,32 @@
> >  #include <linux/tpm.h>
> >  
> >  /**
> > - * tpm_buf_init() - Initialize from the heap
> > + * tpm_buf_init() - Initialize a TPM buffer
> >   * @buf:	A @tpm_buf
> > + * @sized:	Represent a sized buffer (TPM2B)
> > + * @alloc:	Allocate from the heap
> >   *
> >   * Initialize all structure fields to zero, allocate a page from the heap, and
>
> Depending on what the decision ends up being on the bools, flags,
> separate functions, or wrappers possibly an "if needed" should be
> tacked on to the end of "allocate a page from the heap" here.
>
>
> Flags would be better when coming across calls to the routine in the
> code than the bools, but I think switching to wrappers around
> a __tpm_buf_init for the different types would be good.

Yeah, I'll bake something based on this discussion.

BR, Jarkko

[PATCH v3 6/6] KEYS: trusted: tpm2: Use struct tpm_buf for sized buffers

[Jarkko Sakkinen]

Take advantage of the new sized buffer (TPM2B) mode of struct tpm_buf in
tpm2_seal_trusted(). This allows to add robustness to the command
construction without requiring to calculate buffer sizes manually.

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
v2:
* Use tpm_buf_read_*
---
 security/keys/trusted-keys/trusted_tpm2.c | 51 +++++++++++++----------
 1 file changed, 29 insertions(+), 22 deletions(-)

diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index c41f30770138..5d262306184c 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -228,8 +228,9 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 		      struct trusted_key_payload *payload,
 		      struct trusted_key_options *options)
 {
+	off_t offset = TPM_HEADER_SIZE;
+	struct tpm_buf buf, sized;
 	int blob_len = 0;
-	struct tpm_buf buf;
 	u32 hash;
 	u32 flags;
 	int i;
@@ -258,6 +259,13 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 		return rc;
 	}
 
+	rc = tpm_buf_init(&sized, true, true);
+	if (rc) {
+		tpm_buf_destroy(&buf);
+		tpm_put_ops(chip);
+		return rc;
+	}
+
 	tpm_buf_reset(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE);
 	tpm_buf_append_u32(&buf, options->keyhandle);
 	tpm2_buf_append_auth(&buf, TPM2_RS_PW,
@@ -267,36 +275,36 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 			     TPM_DIGEST_SIZE);
 
 	/* sensitive */
-	tpm_buf_append_u16(&buf, 4 + options->blobauth_len + payload->key_len);
+	tpm_buf_append_u16(&sized, options->blobauth_len);
 
-	tpm_buf_append_u16(&buf, options->blobauth_len);
 	if (options->blobauth_len)
-		tpm_buf_append(&buf, options->blobauth, options->blobauth_len);
+		tpm_buf_append(&sized, options->blobauth, options->blobauth_len);
 
-	tpm_buf_append_u16(&buf, payload->key_len);
-	tpm_buf_append(&buf, payload->key, payload->key_len);
+	tpm_buf_append_u16(&sized, payload->key_len);
+	tpm_buf_append(&sized, payload->key, payload->key_len);
+	tpm_buf_append(&buf, sized.data, sized.length);
 
 	/* public */
-	tpm_buf_append_u16(&buf, 14 + options->policydigest_len);
-	tpm_buf_append_u16(&buf, TPM_ALG_KEYEDHASH);
-	tpm_buf_append_u16(&buf, hash);
+	tpm_buf_init(&sized, false, true);
+	tpm_buf_append_u16(&sized, TPM_ALG_KEYEDHASH);
+	tpm_buf_append_u16(&sized, hash);
 
 	/* key properties */
 	flags = 0;
 	flags |= options->policydigest_len ? 0 : TPM2_OA_USER_WITH_AUTH;
-	flags |= payload->migratable ? 0 : (TPM2_OA_FIXED_TPM |
-					    TPM2_OA_FIXED_PARENT);
-	tpm_buf_append_u32(&buf, flags);
+	flags |= payload->migratable ? 0 : (TPM2_OA_FIXED_TPM | TPM2_OA_FIXED_PARENT);
+	tpm_buf_append_u32(&sized, flags);
 
 	/* policy */
-	tpm_buf_append_u16(&buf, options->policydigest_len);
+	tpm_buf_append_u16(&sized, options->policydigest_len);
 	if (options->policydigest_len)
-		tpm_buf_append(&buf, options->policydigest,
-			       options->policydigest_len);
+		tpm_buf_append(&sized, options->policydigest, options->policydigest_len);
 
 	/* public parameters */
-	tpm_buf_append_u16(&buf, TPM_ALG_NULL);
-	tpm_buf_append_u16(&buf, 0);
+	tpm_buf_append_u16(&sized, TPM_ALG_NULL);
+	tpm_buf_append_u16(&sized, 0);
+
+	tpm_buf_append(&buf, sized.data, sized.length);
 
 	/* outside info */
 	tpm_buf_append_u16(&buf, 0);
@@ -313,21 +321,20 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 	if (rc)
 		goto out;
 
-	blob_len = be32_to_cpup((__be32 *) &buf.data[TPM_HEADER_SIZE]);
+	blob_len = tpm_buf_read_u32(&buf, &offset);
 	if (blob_len > MAX_BLOB_SIZE) {
 		rc = -E2BIG;
 		goto out;
 	}
-	if (tpm_buf_length(&buf) < TPM_HEADER_SIZE + 4 + blob_len) {
+	if (buf.length - offset < blob_len) {
 		rc = -EFAULT;
 		goto out;
 	}
 
-	blob_len = tpm2_key_encode(payload, options,
-				   &buf.data[TPM_HEADER_SIZE + 4],
-				   blob_len);
+	blob_len = tpm2_key_encode(payload, options, &buf.data[offset], blob_len);
 
 out:
+	tpm_buf_destroy(&sized);
 	tpm_buf_destroy(&buf);
 
 	if (rc > 0) {
-- 
2.42.0