From a74f8b36352e79b13d48fa92759c9ea6b78d5817 Mon Sep 17 00:00:00 2001 From: Jarkko Sakkinen Date: Sun, 11 Oct 2015 12:26:58 +0300 Subject: [PATCH] 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 Reviewed-by: Peter Huewe Signed-off-by: Peter Huewe --- 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 36ceb710f0eb..cb46f6267af2 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 @@ -28,6 +29,7 @@ #include #include #include +#include enum tpm_const { TPM_MINOR = 224, /* officially assigned */ @@ -390,6 +392,101 @@ 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; -- 2.20.1