Am Freitag, 16. Oktober 2015, 20:40:25 schrieb Jarkko Sakkinen:
> 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.sakki...@linux.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 36ceb71..cb46f62 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 <leend...@watson.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 */
> @@ -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;
> + }
Why not use WARN_ONCE?
> +
> + 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;
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