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Message-Id: <1444723889-11650-2-git-send-email-jarkko.sakkinen@linux.intel.com>
Date: Tue, 13 Oct 2015 11:11:22 +0300
From: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To: tpmdd-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Cc: peterhuewe@....de, gregkh@...uxfoundation.org,
jgunthorpe@...idianresearch.com,
Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
Marcel Selhorst <tpmdd@...horst.net>
Subject: [PATCH v2 1/4] tpm: introduce tpm_buf
This patch introduces struct tpm_buf that provides a string buffer for
constructing TPM commands. This allows to construct variable sized TPM
commands. For the buffer a page is allocated and mapped, which limits
maximum size to PAGE_SIZE.
Variable sized TPM commands are needed in order to add algorithmic
agility.
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
---
drivers/char/tpm/tpm.h | 97 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 97 insertions(+)
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index f8319a0..df43979 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -1,5 +1,6 @@
/*
* Copyright (C) 2004 IBM Corporation
+ * Copyright (C) 2015 Intel Corporation
*
* Authors:
* Leendert van Doorn <leendert@...son.ibm.com>
@@ -28,6 +29,7 @@
#include <linux/tpm.h>
#include <linux/acpi.h>
#include <linux/cdev.h>
+#include <linux/highmem.h>
enum tpm_const {
TPM_MINOR = 224, /* officially assigned */
@@ -382,6 +384,101 @@ struct tpm_cmd_t {
tpm_cmd_params params;
} __packed;
+/* A string buffer type for constructing TPM commands. This is based on the
+ * ideas of string buffer code in security/keys/trusted.h but is heap based
+ * in order to keep the stack usage minimal.
+ */
+
+enum tpm_buf_flags {
+ TPM_BUF_OVERFLOW = BIT(0),
+};
+
+struct tpm_buf {
+ struct page *data_page;
+ unsigned int flags;
+ u8 *data;
+};
+
+static inline void tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal)
+{
+ struct tpm_input_header *head;
+
+ buf->data_page = alloc_page(GFP_HIGHUSER);
+ if (!buf->data_page)
+ return -ENOMEM;
+
+ buf->flags = 0;
+ buf->data = kmap(buf->data_page);
+
+ head = (struct tpm_input_header *) buf->data;
+
+ head->tag = cpu_to_be16(tag);
+ head->length = cpu_to_be32(sizeof(*head));
+ head->ordinal = cpu_to_be32(ordinal);
+
+ return 0;
+}
+
+static inline void tpm_buf_destroy(struct tpm_buf *buf)
+{
+ kunmap(buf->data_page);
+ __free_page(buf->data_page);
+}
+
+static inline u32 tpm_buf_length(struct tpm_buf *buf)
+{
+ struct tpm_input_header *head = (struct tpm_input_header *) buf->data;
+
+ return be32_to_cpu(head->length);
+}
+
+static inline u16 tpm_buf_tag(struct tpm_buf *buf)
+{
+ struct tpm_input_header *head = (struct tpm_input_header *) buf->data;
+
+ return be16_to_cpu(head->tag);
+}
+
+static inline void tpm_buf_append(struct tpm_buf *buf,
+ const unsigned char *new_data,
+ unsigned int new_len)
+{
+ struct tpm_input_header *head = (struct tpm_input_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) {
+ 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);
+}
+
+static inline void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value)
+{
+ tpm_buf_append(buf, &value, 1);
+}
+
+static inline void tpm_buf_append_u16(struct tpm_buf *buf, const u16 value)
+{
+ __be16 value2 = cpu_to_be16(value);
+
+ tpm_buf_append(buf, (u8 *) &value2, 2);
+}
+
+static inline void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value)
+{
+ __be32 value2 = cpu_to_be32(value);
+
+ tpm_buf_append(buf, (u8 *) &value2, 4);
+}
+
extern struct class *tpm_class;
extern dev_t tpm_devt;
extern const struct file_operations tpm_fops;
--
2.5.0
--
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