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Registered in England and Wales under Company Registration No. 3798903 From: David Howells To: jmorris@namei.org cc: dhowells@redhat.com, mcgrof@gmail.com, zohar@linux.vnet.ibm.com, dwmw2@infradead.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [GIT PULL] MODSIGN: Use PKCS#7 for module signatures [ver #7] MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <24178.1438990638.1@warthog.procyon.org.uk> Content-Transfer-Encoding: 8BIT Date: Sat, 08 Aug 2015 00:37:18 +0100 Message-ID: <24179.1438990638@warthog.procyon.org.uk> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi James, Can you pull this into security/next please? Its aim is twofold: firstly, make the module signatures of PKCS#7/CMS format rather than a home-brewed format and secondly to pave the way for use of the signing code for firmware signatures (to follow later). To this end, the patchset effects the following changes: (1) Extracts both parts of an X.509 AuthorityKeyIdentifier (AKID) extension. We already extract the bit that can match the subjectKeyIdentifier (SKID) of the parent X.509 cert, but we currently ignore the bits that can match the issuer and serialNumber. Looks up an X.509 cert by issuer and serialNumber if those are provided in the AKID. If the keyIdentifier is also provided, checks that the subjectKeyIdentifier of the cert found matches that also. If no issuer and serialNumber are provided in the AKID, looks up an X.509 cert by SKID using the AKID keyIdentifier. This allows module signing to be done with certificates that don't have an SKID by which they can be looked up. (2) Makes use of the PKCS#7 facility to provide module signatures. sign-file is replaced with a program that generates a PKCS#7 message that has no X.509 certs embedded and that has detached data (the module content) and adds it onto the message with magic string and descriptor. (3) The PKCS#7 message supplies all the information that is needed to select the X.509 cert to be used to verify the signature by standard means (including selection of digest algorithm and public key algorithm). No kernel-specific magic values are required. (4) Makes it possible to get sign-file to just write out a file containing the PKCS#7 signature blob. This can be used for debugging and potentially for firmware signing. (5) Extracts the function that does PKCS#7 signature verification on a blob from the module signing code and put it somewhere more general so that other things, such as firmware signing, can make use of it without depending on module config options. (6) Adds support for CMS messages in place of PKCS#7 (they're very similar ASN.1) and makes sign-file create CMS messages instead of PKCS#7. This allows signatures to refer to the verifying key by X.509 cert SKID instead of X.509 cert issuer and serial number. (7) Provides support for providing a password/pin for an encrypted private key to sign-file. (8) Makes it possible to use PKCS#11 with sign-file, thus allowing the use of cryptographic hardware. (9) Overhauls the way the module signing key is handled. If the name in CONFIG_MODULE_SIG_KEY is "signing_key.pem" then a key will be automatically generated and placed in the build directory. If the name is different, autogeneration is suppressed and the file is presumed to be a PEM file containing both the private key and X.509 certificate. (10) Overhauls the way auxiliary trusted keys are added to the kernel. Files matching the pattern "*.x509" are no longer just gathered up and cat'd together. Now CONFIG_SYSTEM_TRUSTED_KEYS must be set to point to a single PEM file containing a set of X.509 certs cat'd together if this facility is desired. (11) Severely restricts what authenticateAttributes are permitted in a PKCS#7 or CMS message and what content type may be used. This is selected by the in-kernel user with the appropriate VERIFYING_*_SIGNATURE constant. Note that the revised sign-file program no longer supports the "-s " option to add an externally generated signature. This is deprecated in favour of using PKCS#11. Note also that the format of the signature file that would be passed to -s has changed. Thanks, David --- The following changes since commit 459c15e53cf7e4e88a78ecfb109af5a267c5500a: Merge tag 'asn1-fixes-20150805' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs into next (2015-08-07 13:27:58 +1000) are available in the git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git tags/modsign-pkcs7-20150807 for you to fetch changes up to d158553fdadb0501551a50fcb9537f73d3ed8e01: PKCS#7: Appropriately restrict authenticated attributes and content type (2015-08-07 16:26:15 +0100) ---------------------------------------------------------------- Module signing with PKCS#7 ---------------------------------------------------------------- David Howells (16): ASN.1: Add an ASN.1 compiler option to dump the element tree ASN.1: Copy string names to tokens in ASN.1 compiler X.509: Extract both parts of the AuthorityKeyIdentifier X.509: Support X.509 lookup by Issuer+Serial form AuthorityKeyIdentifier PKCS#7: Allow detached data to be supplied for signature checking purposes MODSIGN: Provide a utility to append a PKCS#7 signature to a module MODSIGN: Use PKCS#7 messages as module signatures system_keyring.c doesn't need to #include module-internal.h MODSIGN: Extract the blob PKCS#7 signature verifier from module signing PKCS#7: Check content type and versions X.509: Change recorded SKID & AKID to not include Subject or Issuer PKCS#7: Support CMS messages also [RFC5652] sign-file: Generate CMS message as signature instead of PKCS#7 PKCS#7: Improve and export the X.509 ASN.1 time object decoder KEYS: Add a name for PKEY_ID_PKCS7 PKCS#7: Appropriately restrict authenticated attributes and content type David Woodhouse (9): modsign: Abort modules_install when signing fails modsign: Allow password to be specified for signing key modsign: Allow signing key to be PKCS#11 modsign: Allow external signing key to be specified modsign: Extract signing cert from CONFIG_MODULE_SIG_KEY if needed modsign: Use single PEM file for autogenerated key modsign: Add explicit CONFIG_SYSTEM_TRUSTED_KEYS option extract-cert: Cope with multiple X.509 certificates in a single file modsign: Use extract-cert to process CONFIG_SYSTEM_TRUSTED_KEYS Luis R. Rodriguez (1): sign-file: Add option to only create signature file .gitignore | 1 + Documentation/kbuild/kbuild.txt | 5 + Documentation/module-signing.txt | 51 +++- Makefile | 8 +- arch/x86/kernel/kexec-bzimage64.c | 4 +- crypto/asymmetric_keys/Makefile | 8 +- crypto/asymmetric_keys/asymmetric_type.c | 11 + crypto/asymmetric_keys/pkcs7.asn1 | 22 +- crypto/asymmetric_keys/pkcs7_key_type.c | 14 +- crypto/asymmetric_keys/pkcs7_parser.c | 269 ++++++++++++++++++- crypto/asymmetric_keys/pkcs7_parser.h | 20 +- crypto/asymmetric_keys/pkcs7_trust.c | 10 +- crypto/asymmetric_keys/pkcs7_verify.c | 145 ++++++++-- crypto/asymmetric_keys/public_key.c | 1 + crypto/asymmetric_keys/verify_pefile.c | 7 +- crypto/asymmetric_keys/x509_akid.asn1 | 35 +++ crypto/asymmetric_keys/x509_cert_parser.c | 231 ++++++++++------ crypto/asymmetric_keys/x509_parser.h | 12 +- crypto/asymmetric_keys/x509_public_key.c | 95 ++++--- include/crypto/pkcs7.h | 13 +- include/crypto/public_key.h | 18 +- include/keys/system_keyring.h | 7 + include/linux/oid_registry.h | 4 +- include/linux/verify_pefile.h | 6 +- init/Kconfig | 55 +++- kernel/Makefile | 112 +++++--- kernel/module_signing.c | 213 ++------------- kernel/system_certificates.S | 3 + kernel/system_keyring.c | 53 +++- scripts/Makefile | 4 + scripts/Makefile.modinst | 2 +- scripts/asn1_compiler.c | 229 ++++++++++------ scripts/extract-cert.c | 166 ++++++++++++ scripts/sign-file | 421 ------------------------------ scripts/sign-file.c | 260 ++++++++++++++++++ 35 files changed, 1587 insertions(+), 928 deletions(-) create mode 100644 crypto/asymmetric_keys/x509_akid.asn1 create mode 100644 scripts/extract-cert.c delete mode 100755 scripts/sign-file create mode 100755 scripts/sign-file.c