On Thu, 2014-11-20 at 16:54 +0000, David Howells wrote:
> It is possible for a PKCS#7 message to have detached data. However, to verify
> the signatures on a PKCS#7 message, we have to be able to digest the data.
> Provide a function to supply that data. An error is given if the PKCS#7
> message included embedded data.
>
> Signed-off-by: David Howells <[email protected]>
Ok, PCKS#7 supports detached data. I assume this is not needed for
kernel modules. What is the motivation for adding this support to the
kernel?
Mimi
> ---
>
> crypto/asymmetric_keys/pkcs7_verify.c | 26 ++++++++++++++++++++++++++
> include/crypto/pkcs7.h | 3 +++
> 2 files changed, 29 insertions(+)
>
> diff --git a/crypto/asymmetric_keys/pkcs7_verify.c
> b/crypto/asymmetric_keys/pkcs7_verify.c
> index 667064daf66b..c6ee41bfda6e 100644
> --- a/crypto/asymmetric_keys/pkcs7_verify.c
> +++ b/crypto/asymmetric_keys/pkcs7_verify.c
> @@ -382,3 +382,29 @@ int pkcs7_verify(struct pkcs7_message *pkcs7)
> return enopkg;
> }
> EXPORT_SYMBOL_GPL(pkcs7_verify);
> +
> +/**
> + * pkcs7_supply_detached_data - Supply the data needed to verify a PKCS#7
> message
> + * @pkcs7: The PKCS#7 message
> + * @data: The data to be verified
> + * @datalen: The amount of data
> + *
> + * Supply the detached data needed to verify a PKCS#7 message. Note that no
> + * attempt to retain/pin the data is made. That is left to the caller. The
> + * data will not be modified by pkcs7_verify() and will not be freed when the
> + * PKCS#7 message is freed.
> + *
> + * Returns -EINVAL if data is already supplied in the message, 0 otherwise.
> + */
> +int pkcs7_supply_detached_data(struct pkcs7_message *pkcs7,
> + const void *data, size_t datalen)
> +{
> + if (pkcs7->data) {
> + pr_debug("Data already supplied\n");
> + return -EINVAL;
> + }
> + pkcs7->data = data;
> + pkcs7->data_len = datalen;
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(pkcs7_supply_detached_data);
> diff --git a/include/crypto/pkcs7.h b/include/crypto/pkcs7.h
> index 691c79172a26..e235ab4957ee 100644
> --- a/include/crypto/pkcs7.h
> +++ b/include/crypto/pkcs7.h
> @@ -34,3 +34,6 @@ extern int pkcs7_validate_trust(struct pkcs7_message *pkcs7,
> * pkcs7_verify.c
> */
> extern int pkcs7_verify(struct pkcs7_message *pkcs7);
> +
> +extern int pkcs7_supply_detached_data(struct pkcs7_message *pkcs7,
> + const void *data, size_t datalen);
>
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