tpm: Store the length of the tpm_buf data separately.

TPM2B buffers, or sized buffers, have a two byte header, which contains the
length of the payload as a 16-bit big-endian number, without counting in
the space taken by the header. This differs from encoding in the TPM header
where the length includes also the bytes taken by the header.

Unbound the length of a tpm_buf from the value stored to the TPM command
header. A separate encoding and decoding step so that different buffer
types can be supported, with variant header format and length encoding.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
index 96cee41d5b9c1393510cad4f207f79741bdcbe1a..2f2710ca6f6d1dd31d3dde26d1305f4e77beecbb 100644 (file)
--- a/drivers/char/tpm/tpm-buf.c
+++ b/drivers/char/tpm/tpm-buf.c
@@ -3,25 +3,44 @@
  * Handling of TPM command and other buffers.
  */
 
+#include <linux/tpm_command.h>
 #include <linux/module.h>
 #include <linux/tpm.h>
 
+/**
+ * tpm_buf_init() - Allocate and 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
+ *
+ * Return: 0 or -ENOMEM
+ */
 int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal)
 {
        buf->data = (u8 *)__get_free_page(GFP_KERNEL);
        if (!buf->data)
                return -ENOMEM;
 
-       buf->flags = 0;
        tpm_buf_reset(buf, tag, ordinal);
        return 0;
 }
 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;
 
+       WARN_ON(tag != TPM_TAG_RQU_COMMAND && tag != TPM2_ST_NO_SESSIONS &&
+               tag != TPM2_ST_SESSIONS && tag != 0);
+
+       buf->flags = 0;
+       buf->length = sizeof(*head);
        head->tag = cpu_to_be16(tag);
        head->length = cpu_to_be32(sizeof(*head));
        head->ordinal = cpu_to_be32(ordinal);
@@ -34,33 +53,41 @@ 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 data
+ * @buf:       A &tpm_buf
+ *
+ * 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 f940045a014e8b2a5572c3ac4761a4976642c27f..5da134f12c9a470fb83f85574b46b6105466111a 100644 (file)
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -232,6 +232,7 @@ 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;
        return 0;
 }
 EXPORT_SYMBOL_GPL(tpm_transmit_cmd);

diff --git a/include/keys/trusted_tpm.h b/include/keys/trusted_tpm.h
index 7769b726863ab10b5b160366d7fa918784491995..a088b33fd0e3b7d5ed981fcbda082b03c9933461 100644 (file)
--- a/include/keys/trusted_tpm.h
+++ b/include/keys/trusted_tpm.h
@@ -6,8 +6,6 @@
 #include <linux/tpm_command.h>
 
 /* implementation specific TPM constants */
-#define MAX_BUF_SIZE                   1024
-#define TPM_GETRANDOM_SIZE             14
 #define TPM_SIZE_OFFSET                        2
 #define TPM_RETURN_OFFSET              6
 #define TPM_DATA_OFFSET                        10

diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 0a8c1351adc29b10f39b43182eabf483c361d8ae..1d7b39b5c383accc9abf7196529235c50c107408 100644 (file)
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -306,7 +306,8 @@ enum tpm_buf_flags {
  * A string buffer type for constructing TPM commands.
  */
 struct tpm_buf {
-       unsigned int flags;
+       u32 flags;
+       u32 length;
        u8 *data;
 };
 
@@ -329,8 +330,7 @@ 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);

diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c
index 37bce84eef993275e9da814b0dec4a288c1a5bf3..89c9798d18007192f30e6cd21605b78cd6cb55d9 100644 (file)
--- a/security/keys/trusted-keys/trusted_tpm1.c
+++ b/security/keys/trusted-keys/trusted_tpm1.c
@@ -367,6 +367,7 @@ int trusted_tpm_send(unsigned char *cmd, size_t buflen)
                return rc;
 
        buf.flags = 0;
+       buf.length = buflen;
        buf.data = cmd;
        dump_tpm_buf(cmd);
        rc = tpm_transmit_cmd(chip, &buf, 4, "sending data");
@@ -417,7 +418,7 @@ 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;
 
@@ -441,7 +442,7 @@ 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;
 
@@ -553,7 +554,7 @@ 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;
 
@@ -644,7 +645,7 @@ 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;