Some versions of openssl might have the CMS feature disabled
LibreSSL disables this feature too
If the feature is disabled, fallback to PKCS7

In file included from scripts/sign-file.c:46:0:
/usr/x86_64-pc-linux-gnu/include/openssl/cms.h:62:2: error: #error CMS is disabled.
 #error CMS is disabled.

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
Signed-off-by: David Howells <dhowells@redhat.com>

This patch adds support for signing a kernel module with a raw
detached PKCS#7 signature/message.

The signature is not converted and is simply appended to the module so
it needs to be in the right format. Using openssl, a valid signature can
be generated like this:
  $ openssl smime -sign -nocerts -noattr -binary -in <module> -inkey \
    <key> -signer <x509> -outform der -out <raw sig>

The resulting raw signature from the above command is (more or less)
identical to the raw signature that sign-file itself can produce like
this:
  $ scripts/sign-file -d <hash algo> <key> <x509> <module>

Signed-off-by: Juerg Haefliger <juerg.haefliger@hpe.com>
Signed-off-by: David Howells <dhowells@redhat.com>

In file included from scripts/sign-file.c:47:0:
/usr/include/openssl/cms.h:62:2: error: #error CMS is disabled.
 #error CMS is disabled.
  ^
scripts/Makefile.host:91: recipe for target 'scripts/sign-file' failed
make[1]: *** [scripts/sign-file] Error 1
Makefile:567: recipe for target 'scripts' failed
make: *** [scripts] Error 2


Fix SSL headers so that the kernel can build with LibreSSL

Signed-off-by: Codarren Velvindron <codarren@hackers.mu>
Acked-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: David Howells <dhowells@redhat.com>

The sign-file.c program actually uses CMS rather than PKCS#7 to sign a file
since that allows the target X.509 certificate to be specified by
subjectKeyId rather than by issuer + serialNumber.

However, older versions of the OpenSSL crypto library (such as may be found
in CentOS 5.11) don't support CMS.  Assume everything prior to
OpenSSL-1.0.0 doesn't support CMS and switch to using PKCS#7 in that case.

Further, the pre-1.0.0 OpenSSL only supports PKCS#7 signing with SHA1, so
give an error from the sign-file script if the caller requests anything
other than SHA1.

The compiler gives the following error with an OpenSSL crypto library
that's too old:

  HOSTCC  scripts/sign-file
scripts/sign-file.c:23:25: fatal error: openssl/cms.h: No such file or directory
 #include <openssl/cms.h>

Reported-by: Vinson Lee <vlee@twopensource.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: David Woodhouse <David.Woodhouse@intel.com>

The GPL does not permit us to link against the OpenSSL library. Use
LGPL for sign-file and extract-file instead.

[ The whole "openssl isn't compatible with gpl" is really just
  fear-mongering, but there's no reason not to make modsign LGPL, so
  nobody cares.  - Linus ]

Reported-by: Julian Andres Klode <jak@jak-linux.org>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Julian Andres Klode <jak@jak-linux.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Fix the following warning:

	scripts/sign-file.c: In function ‘main’:
	scripts/sign-file.c:188: warning: value computed is not used

whereby the result of BIO_ctrl() is cast inside of BIO_reset() to an
integer of a different size - which we're not checking but probably should.

Reported-by: James Morris <jmorris@namei.org>
Signed-off-by: David Howells <dhowells@redhat.com>

A PKCS#7 or CMS message can have per-signature authenticated attributes
that are digested as a lump and signed by the authorising key for that
signature.  If such attributes exist, the content digest isn't itself
signed, but rather it is included in a special authattr which then
contributes to the signature.

Further, we already require the master message content type to be
pkcs7_signedData - but there's also a separate content type for the data
itself within the SignedData object and this must be repeated inside the
authattrs for each signer [RFC2315 9.2, RFC5652 11.1].

We should really validate the authattrs if they exist or forbid them
entirely as appropriate.  To this end:

 (1) Alter the PKCS#7 parser to reject any message that has more than one
     signature where at least one signature has authattrs and at least one
     that does not.

 (2) Validate authattrs if they are present and strongly restrict them.
     Only the following authattrs are permitted and all others are
     rejected:

     (a) contentType.  This is checked to be an OID that matches the
     	 content type in the SignedData object.

     (b) messageDigest.  This must match the crypto digest of the data.

     (c) signingTime.  If present, we check that this is a valid, parseable
     	 UTCTime or GeneralTime and that the date it encodes fits within
     	 the validity window of the matching X.509 cert.

     (d) S/MIME capabilities.  We don't check the contents.

     (e) Authenticode SP Opus Info.  We don't check the contents.

     (f) Authenticode Statement Type.  We don't check the contents.

     The message is rejected if (a) or (b) are missing.  If the message is
     an Authenticode type, the message is rejected if (e) is missing; if
     not Authenticode, the message is rejected if (d) - (f) are present.

     The S/MIME capabilities authattr (d) unfortunately has to be allowed
     to support kernels already signed by the pesign program.  This only
     affects kexec.  sign-file suppresses them (CMS_NOSMIMECAP).

     The message is also rejected if an authattr is given more than once or
     if it contains more than one element in its set of values.

 (3) Add a parameter to pkcs7_verify() to select one of the following
     restrictions and pass in the appropriate option from the callers:

     (*) VERIFYING_MODULE_SIGNATURE

	 This requires that the SignedData content type be pkcs7-data and
	 forbids authattrs.  sign-file sets CMS_NOATTR.  We could be more
	 flexible and permit authattrs optionally, but only permit minimal
	 content.

     (*) VERIFYING_FIRMWARE_SIGNATURE

	 This requires that the SignedData content type be pkcs7-data and
	 requires authattrs.  In future, this will require an attribute
	 holding the target firmware name in addition to the minimal set.

     (*) VERIFYING_UNSPECIFIED_SIGNATURE

	 This requires that the SignedData content type be pkcs7-data but
	 allows either no authattrs or only permits the minimal set.

     (*) VERIFYING_KEXEC_PE_SIGNATURE

	 This only supports the Authenticode SPC_INDIRECT_DATA content type
	 and requires at least an SpcSpOpusInfo authattr in addition to the
	 minimal set.  It also permits an SPC_STATEMENT_TYPE authattr (and
	 an S/MIME capabilities authattr because the pesign program doesn't
	 remove these).

     (*) VERIFYING_KEY_SIGNATURE
     (*) VERIFYING_KEY_SELF_SIGNATURE

	 These are invalid in this context but are included for later use
	 when limiting the use of X.509 certs.

 (4) The pkcs7_test key type is given a module parameter to select between
     the above options for testing purposes.  For example:

	echo 1 >/sys/module/pkcs7_test_key/parameters/usage
	keyctl padd pkcs7_test foo @s </tmp/stuff.pkcs7

     will attempt to check the signature on stuff.pkcs7 as if it contains a
     firmware blob (1 being VERIFYING_FIRMWARE_SIGNATURE).

Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: David Woodhouse <David.Woodhouse@intel.com>

Make sign-file use the OpenSSL CMS routines to generate a message to be
used as the signature blob instead of the PKCS#7 routines.  This allows us
to change how the matching X.509 certificate is selected.  With PKCS#7 the
only option is to match on the serial number and issuer fields of an X.509
certificate; with CMS, we also have the option of matching by subjectKeyId
extension.  The new behaviour is selected with the "-k" flag.

Without the -k flag specified, the output is pretty much identical to the
PKCS#7 output.

Whilst we're at it, don't include the S/MIME capability list in the message
as it's irrelevant to us.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-By: David Woodhouse <David.Woodhouse@intel.com

This is only the key; the corresponding *cert* still needs to be in
$(topdir)/signing_key.x509. And there's no way to actually use this
from the build system yet.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: David Howells <dhowells@redhat.com>

We don't want this in the Kconfig since it might then get exposed in
/proc/config.gz. So make it a parameter to Kbuild instead. This also
means we don't have to jump through hoops to strip quotes from it, as
we would if it was a config option.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Mimi Zohar <zohar@linux.vnet.ibm.com>