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PKCS#7: Allow detached data to be supplied for signature checking purposes

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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.

This is used in a subsequent patch to supply the data to module signing where
the signature is in the form of a PKCS#7 message with detached data, whereby
the detached data is the module content that is signed.

Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Vivek Goyal <vgoyal@redhat.com>
This commit is contained in:
David Howells 2015-07-20 21:16:26 +01:00
parent 4573b64a31
commit 4ebdb76f7d
2 changed files with 28 additions and 0 deletions
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25
crypto/asymmetric_keys/pkcs7_verify.c
View File

@ -382,3 +382,28 @@ 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;
}

3
include/crypto/pkcs7.h
View File

@ -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);