linux-kernel - [PATCH 22/23] PEFILE: Load the contained key if we consider the container to be validly signed

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Date:	Tue, 30 Oct 2012 19:22:39 +0000
From:	David Howells <dhowells@...hat.com>
To:	rusty@...tcorp.com.au
Cc:	dhowells@...hat.com, pjones@...hat.com, jwboyer@...hat.com,
	mjg@...hat.com, dmitry.kasatkin@...el.com,
	zohar@...ux.vnet.ibm.com, keescook@...omium.org,
	keyrings@...ux-nfs.org, linux-kernel@...r.kernel.org
Subject: [PATCH 22/23] PEFILE: Load the contained key if we consider the
 container to be validly signed

Load the key contained in the PE binary if the signature on the container can
be verified by following the chain of X.509 certificates in the PKCS#7 message
to a key that we already trust.  Typically, the trusted key will be acquired
from a source outside of the kernel, such as the UEFI database.

Signed-off-by: David Howells <dhowells@...hat.com>
---

 crypto/asymmetric_keys/pefile_parser.c   |   11 ++++++++++-
 crypto/asymmetric_keys/x509_parser.h     |    3 +++
 crypto/asymmetric_keys/x509_public_key.c |    2 +-
 3 files changed, 14 insertions(+), 2 deletions(-)


diff --git a/crypto/asymmetric_keys/pefile_parser.c b/crypto/asymmetric_keys/pefile_parser.c
index 1ab1890..28be7d3 100644
--- a/crypto/asymmetric_keys/pefile_parser.c
+++ b/crypto/asymmetric_keys/pefile_parser.c
@@ -389,6 +389,8 @@ static int pefile_key_preparse(struct key_preparsed_payload *prep)
 {
 	struct pkcs7_message *pkcs7;
 	struct pefile_context ctx;
+	const void *saved_data;
+	size_t saved_datalen;
 	int ret;
 
 	kenter("");
@@ -434,7 +436,14 @@ static int pefile_key_preparse(struct key_preparsed_payload *prep)
 	if (ret < 0)
 		goto error;
 
-	ret = -ENOANO; // Not yet complete
+	/* We can now try to load the key */
+	saved_data = prep->data;
+	saved_datalen = prep->datalen;
+	prep->data += ctx.keylist_offset;
+	prep->datalen = ctx.keylist_len;
+	ret = x509_key_preparse(prep);
+	prep->data = saved_data;
+	prep->datalen = saved_datalen;
 
 error:
 	pkcs7_free_message(ctx.pkcs7);
diff --git a/crypto/asymmetric_keys/x509_parser.h b/crypto/asymmetric_keys/x509_parser.h
index 5e35fba..65452c4 100644
--- a/crypto/asymmetric_keys/x509_parser.h
+++ b/crypto/asymmetric_keys/x509_parser.h
@@ -12,6 +12,8 @@
 #include <linux/time.h>
 #include <crypto/public_key.h>
 
+struct key_preparsed_payload;
+
 struct x509_certificate {
 	struct x509_certificate *next;
 	const struct x509_certificate *signer;	/* Certificate that signed this one */
@@ -47,3 +49,4 @@ extern struct x509_certificate *x509_cert_parse(const void *data, size_t datalen
 extern int x509_get_sig_params(struct x509_certificate *cert);
 extern int x509_check_signature(const struct public_key *pub,
 				struct x509_certificate *cert);
+extern int x509_key_preparse(struct key_preparsed_payload *prep);
diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
index 3a87512..b37f2a6 100644
--- a/crypto/asymmetric_keys/x509_public_key.c
+++ b/crypto/asymmetric_keys/x509_public_key.c
@@ -105,7 +105,7 @@ EXPORT_SYMBOL_GPL(x509_check_signature);
 /*
  * Attempt to parse a data blob for a key as an X509 certificate.
  */
-static int x509_key_preparse(struct key_preparsed_payload *prep)
+int x509_key_preparse(struct key_preparsed_payload *prep)
 {
 	struct x509_certificate *cert;
 	struct tm now;

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