Here's a set of patches that implements a PKCS#7 message parser in the kernel.
The PKCS#7 message parsing will then be used to limit kexec to authenticated
kernels only if so configured.
The patches provide the following facilities:
(1) Parse an ASN.1 PKCS#7 message and pick out useful bits such as the data
content and the X.509 certificates used to sign it and all the data
signatures.
(2) Verify all the data signatures against the set of X.509 certificates
available in the message.
(3) Follow the certificate chains and verify that:
(a) for every self-signed X.509 certificate, check that it validly signed
itself, and:
(b) for every non-self-signed certificate, if we have a 'parent'
certificate, the former is validly signed by the latter.
(4) Look for intersections between the certificate chains and the trusted
keyring, if any intersections are found, verify that the trusted
certificates signed the intersection point in the chain.
(5) For testing purposes, a key type can be made available that will take a
PKCS#7 message, check that the message is trustworthy, and if so, add its
data content into the key.
They can be found on this branch also:
http://git.kernel.org/cgit/linux/kernel/git/dhowells/linux-modsign.git/log/?h=pkcs7
and are tagged with:
keys-pkcs7-20140708
David
---
David Howells (7):
X.509: Export certificate parse and free functions
PKCS#7: Implement a parser [RFC 2315]
PKCS#7: Digest the data in a signed-data message
PKCS#7: Find the right key in the PKCS#7 key list and verify the signature
PKCS#7: Verify internal certificate chain
PKCS#7: Find intersection between PKCS#7 message and known, trusted keys
PKCS#7: Provide a key type for testing PKCS#7
crypto/asymmetric_keys/Kconfig | 22 ++
crypto/asymmetric_keys/Makefile | 22 ++
crypto/asymmetric_keys/pkcs7.asn1 | 127 +++++++++
crypto/asymmetric_keys/pkcs7_key_type.c | 97 +++++++
crypto/asymmetric_keys/pkcs7_parser.c | 396 +++++++++++++++++++++++++++++
crypto/asymmetric_keys/pkcs7_parser.h | 61 ++++
crypto/asymmetric_keys/pkcs7_trust.c | 219 ++++++++++++++++
crypto/asymmetric_keys/pkcs7_verify.c | 323 ++++++++++++++++++++++++
crypto/asymmetric_keys/x509_cert_parser.c | 3
include/crypto/pkcs7.h | 36 +++
include/linux/oid_registry.h | 1
11 files changed, 1307 insertions(+)
create mode 100644 crypto/asymmetric_keys/pkcs7.asn1
create mode 100644 crypto/asymmetric_keys/pkcs7_key_type.c
create mode 100644 crypto/asymmetric_keys/pkcs7_parser.c
create mode 100644 crypto/asymmetric_keys/pkcs7_parser.h
create mode 100644 crypto/asymmetric_keys/pkcs7_trust.c
create mode 100644 crypto/asymmetric_keys/pkcs7_verify.c
create mode 100644 include/crypto/pkcs7.h
