Merge tag 'keys-pefile-20140709' into keys-next (6204e002) · Commits · e / devices / android_kernel_fairphone_FP3

crypto/asymmetric_keys/Kconfig

+10 −1

Original line number	Diff line number	Diff line
		@@ -33,7 +33,7 @@ config X509_CERTIFICATE_PARSER
		select ASN1
		select OID_REGISTRY
		help
		This option procides support for parsing X.509 format blobs for key
		This option provides support for parsing X.509 format blobs for key
		data and provides the ability to instantiate a crypto key from a
		public key packet found inside the certificate.

		@@ -59,4 +59,13 @@ config PKCS7_TEST_KEY

		This is intended for testing the PKCS#7 parser.

		config SIGNED_PE_FILE_VERIFICATION
		bool "Support for PE file signature verification"
		depends on PKCS7_MESSAGE_PARSER=y
		select ASN1
		select OID_REGISTRY
		help
		This option provides support for verifying the signature(s) on a
		signed PE binary.

		endif # ASYMMETRIC_KEY_TYPE

crypto/asymmetric_keys/Makefile

+15 −0

Original line number	Diff line number	Diff line
		@@ -47,3 +47,18 @@ clean-files += pkcs7-asn1.c pkcs7-asn1.h
		obj-$(CONFIG_PKCS7_TEST_KEY) += pkcs7_test_key.o
		pkcs7_test_key-y := \
		pkcs7_key_type.o

		#
		# Signed PE binary-wrapped key handling
		#
		obj-$(CONFIG_SIGNED_PE_FILE_VERIFICATION) += verify_signed_pefile.o

		verify_signed_pefile-y := \
		verify_pefile.o \
		mscode_parser.o \
		mscode-asn1.o

		$(obj)/mscode_parser.o: $(obj)/mscode-asn1.h $(obj)/mscode-asn1.h
		$(obj)/mscode-asn1.o: $(obj)/mscode-asn1.c $(obj)/mscode-asn1.h

		clean-files += mscode-asn1.c mscode-asn1.h

crypto/asymmetric_keys/mscode.asn1

0 → 100644

+28 −0

Original line number	Diff line number	Diff line
		--- Microsoft individual code signing data blob parser
		---
		--- Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
		--- Written by David Howells (dhowells@redhat.com)
		---
		--- This program is free software; you can redistribute it and/or
		--- modify it under the terms of the GNU General Public Licence
		--- as published by the Free Software Foundation; either version
		--- 2 of the Licence, or (at your option) any later version.
		---

		MSCode ::= SEQUENCE {
		type SEQUENCE {
		contentType ContentType,
		parameters ANY
		},
		content SEQUENCE {
		digestAlgorithm DigestAlgorithmIdentifier,
		digest OCTET STRING ({ mscode_note_digest })
		}
		}

		ContentType ::= OBJECT IDENTIFIER ({ mscode_note_content_type })

		DigestAlgorithmIdentifier ::= SEQUENCE {
		algorithm OBJECT IDENTIFIER ({ mscode_note_digest_algo }),
		parameters ANY OPTIONAL
		}

crypto/asymmetric_keys/mscode_parser.c

0 → 100644

+126 −0

Original line number	Diff line number	Diff line
		/* Parse a Microsoft Individual Code Signing blob
		*
		* Copyright (C) 2014 Red Hat, Inc. All Rights Reserved.
		* Written by David Howells (dhowells@redhat.com)
		*
		* This program is free software; you can redistribute it and/or
		* modify it under the terms of the GNU General Public Licence
		* as published by the Free Software Foundation; either version
		* 2 of the Licence, or (at your option) any later version.
		*/

		#define pr_fmt(fmt) "MSCODE: "fmt
		#include <linux/kernel.h>
		#include <linux/slab.h>
		#include <linux/err.h>
		#include <linux/oid_registry.h>
		#include <crypto/pkcs7.h>
		#include "verify_pefile.h"
		#include "mscode-asn1.h"

		/*
		* Parse a Microsoft Individual Code Signing blob
		*/
		int mscode_parse(struct pefile_context *ctx)
		{
		const void *content_data;
		size_t data_len;
		int ret;

		ret = pkcs7_get_content_data(ctx->pkcs7, &content_data, &data_len, 1);

		if (ret) {
		pr_debug("PKCS#7 message does not contain data\n");
		return ret;
		}

		pr_devel("Data: %zu [%*ph]\n", data_len, (unsigned)(data_len),
		content_data);

		return asn1_ber_decoder(&mscode_decoder, ctx, content_data, data_len);
		}

		/*
		* Check the content type OID
		*/
		int mscode_note_content_type(void *context, size_t hdrlen,
		unsigned char tag,
		const void *value, size_t vlen)
		{
		enum OID oid;

		oid = look_up_OID(value, vlen);
		if (oid == OID__NR) {
		char buffer[50];

		sprint_oid(value, vlen, buffer, sizeof(buffer));
		pr_err("Unknown OID: %s\n", buffer);
		return -EBADMSG;
		}

		/*
		* pesign utility had a bug where it was putting
		* OID_msIndividualSPKeyPurpose instead of OID_msPeImageDataObjId
		* So allow both OIDs.
		*/
		if (oid != OID_msPeImageDataObjId &&
		oid != OID_msIndividualSPKeyPurpose) {
		pr_err("Unexpected content type OID %u\n", oid);
		return -EBADMSG;
		}

		return 0;
		}

		/*
		* Note the digest algorithm OID
		*/
		int mscode_note_digest_algo(void *context, size_t hdrlen,
		unsigned char tag,
		const void *value, size_t vlen)
		{
		struct pefile_context *ctx = context;
		char buffer[50];
		enum OID oid;

		oid = look_up_OID(value, vlen);
		switch (oid) {
		case OID_md4:
		ctx->digest_algo = HASH_ALGO_MD4;
		break;
		case OID_md5:
		ctx->digest_algo = HASH_ALGO_MD5;
		break;
		case OID_sha1:
		ctx->digest_algo = HASH_ALGO_SHA1;
		break;
		case OID_sha256:
		ctx->digest_algo = HASH_ALGO_SHA256;
		break;

		case OID__NR:
		sprint_oid(value, vlen, buffer, sizeof(buffer));
		pr_err("Unknown OID: %s\n", buffer);
		return -EBADMSG;

		default:
		pr_err("Unsupported content type: %u\n", oid);
		return -ENOPKG;
		}

		return 0;
		}

		/*
		* Note the digest we're guaranteeing with this certificate
		*/
		int mscode_note_digest(void *context, size_t hdrlen,
		unsigned char tag,
		const void *value, size_t vlen)
		{
		struct pefile_context *ctx = context;

		ctx->digest = value;
		ctx->digest_len = vlen;
		return 0;
		}

crypto/asymmetric_keys/verify_pefile.c

0 → 100644

+457 −0

Original line number	Diff line number	Diff line
		/* Parse a signed PE binary
		*
		* Copyright (C) 2014 Red Hat, Inc. All Rights Reserved.
		* Written by David Howells (dhowells@redhat.com)
		*
		* This program is free software; you can redistribute it and/or
		* modify it under the terms of the GNU General Public Licence
		* as published by the Free Software Foundation; either version
		* 2 of the Licence, or (at your option) any later version.
		*/

		#define pr_fmt(fmt) "PEFILE: "fmt
		#include <linux/module.h>
		#include <linux/kernel.h>
		#include <linux/slab.h>
		#include <linux/err.h>
		#include <linux/pe.h>
		#include <linux/asn1.h>
		#include <crypto/pkcs7.h>
		#include <crypto/hash.h>
		#include "verify_pefile.h"

		/*
		* Parse a PE binary.
		*/
		static int pefile_parse_binary(const void *pebuf, unsigned int pelen,
		struct pefile_context *ctx)
		{
		const struct mz_hdr *mz = pebuf;
		const struct pe_hdr *pe;
		const struct pe32_opt_hdr *pe32;
		const struct pe32plus_opt_hdr *pe64;
		const struct data_directory *ddir;
		const struct data_dirent *dde;
		const struct section_header secs, sec;
		size_t cursor, datalen = pelen;

		kenter("");

		#define chkaddr(base, x, s) \
		do { \
		if ((x) < base \|\| (s) >= datalen \|\| (x) > datalen - (s)) \
		return -ELIBBAD; \
		} while (0)

		chkaddr(0, 0, sizeof(*mz));
		if (mz->magic != MZ_MAGIC)
		return -ELIBBAD;
		cursor = sizeof(*mz);

		chkaddr(cursor, mz->peaddr, sizeof(*pe));
		pe = pebuf + mz->peaddr;
		if (pe->magic != PE_MAGIC)
		return -ELIBBAD;
		cursor = mz->peaddr + sizeof(*pe);

		chkaddr(0, cursor, sizeof(pe32->magic));
		pe32 = pebuf + cursor;
		pe64 = pebuf + cursor;

		switch (pe32->magic) {
		case PE_OPT_MAGIC_PE32:
		chkaddr(0, cursor, sizeof(*pe32));
		ctx->image_checksum_offset =
		(unsigned long)&pe32->csum - (unsigned long)pebuf;
		ctx->header_size = pe32->header_size;
		cursor += sizeof(*pe32);
		ctx->n_data_dirents = pe32->data_dirs;
		break;

		case PE_OPT_MAGIC_PE32PLUS:
		chkaddr(0, cursor, sizeof(*pe64));
		ctx->image_checksum_offset =
		(unsigned long)&pe64->csum - (unsigned long)pebuf;
		ctx->header_size = pe64->header_size;
		cursor += sizeof(*pe64);
		ctx->n_data_dirents = pe64->data_dirs;
		break;

		default:
		pr_debug("Unknown PEOPT magic = %04hx\n", pe32->magic);
		return -ELIBBAD;
		}

		pr_debug("checksum @ %x\n", ctx->image_checksum_offset);
		pr_debug("header size = %x\n", ctx->header_size);

		if (cursor >= ctx->header_size \|\| ctx->header_size >= datalen)
		return -ELIBBAD;

		if (ctx->n_data_dirents > (ctx->header_size - cursor) / sizeof(*dde))
		return -ELIBBAD;

		ddir = pebuf + cursor;
		cursor += sizeof(dde) ctx->n_data_dirents;

		ctx->cert_dirent_offset =
		(unsigned long)&ddir->certs - (unsigned long)pebuf;
		ctx->certs_size = ddir->certs.size;

		if (!ddir->certs.virtual_address \|\| !ddir->certs.size) {
		pr_debug("Unsigned PE binary\n");
		return -EKEYREJECTED;
		}

		chkaddr(ctx->header_size, ddir->certs.virtual_address,
		ddir->certs.size);
		ctx->sig_offset = ddir->certs.virtual_address;
		ctx->sig_len = ddir->certs.size;
		pr_debug("cert = %x @%x [%*ph]\n",
		ctx->sig_len, ctx->sig_offset,
		ctx->sig_len, pebuf + ctx->sig_offset);

		ctx->n_sections = pe->sections;
		if (ctx->n_sections > (ctx->header_size - cursor) / sizeof(*sec))
		return -ELIBBAD;
		ctx->secs = secs = pebuf + cursor;

		return 0;
		}

		/*
		* Check and strip the PE wrapper from around the signature and check that the
		* remnant looks something like PKCS#7.
		*/
		static int pefile_strip_sig_wrapper(const void *pebuf,
		struct pefile_context *ctx)
		{
		struct win_certificate wrapper;
		const u8 *pkcs7;

		if (ctx->sig_len < sizeof(wrapper)) {
		pr_debug("Signature wrapper too short\n");
		return -ELIBBAD;
		}

		memcpy(&wrapper, pebuf + ctx->sig_offset, sizeof(wrapper));
		pr_debug("sig wrapper = { %x, %x, %x }\n",
		wrapper.length, wrapper.revision, wrapper.cert_type);

		/* Both pesign and sbsign round up the length of certificate table
		* (in optional header data directories) to 8 byte alignment.
		*/
		if (round_up(wrapper.length, 8) != ctx->sig_len) {
		pr_debug("Signature wrapper len wrong\n");
		return -ELIBBAD;
		}
		if (wrapper.revision != WIN_CERT_REVISION_2_0) {
		pr_debug("Signature is not revision 2.0\n");
		return -ENOTSUPP;
		}
		if (wrapper.cert_type != WIN_CERT_TYPE_PKCS_SIGNED_DATA) {
		pr_debug("Signature certificate type is not PKCS\n");
		return -ENOTSUPP;
		}

		/* Looks like actual pkcs signature length is in wrapper->length.
		* size obtained from data dir entries lists the total size of
		* certificate table which is also aligned to octawrod boundary.
		*
		* So set signature length field appropriately.
		*/
		ctx->sig_len = wrapper.length;
		ctx->sig_offset += sizeof(wrapper);
		ctx->sig_len -= sizeof(wrapper);
		if (ctx->sig_len == 0) {
		pr_debug("Signature data missing\n");
		return -EKEYREJECTED;
		}

		/* What's left should a PKCS#7 cert */
		pkcs7 = pebuf + ctx->sig_offset;
		if (pkcs7[0] == (ASN1_CONS_BIT \| ASN1_SEQ)) {
		if (pkcs7[1] == 0x82 &&
		pkcs7[2] == (((ctx->sig_len - 4) >> 8) & 0xff) &&
		pkcs7[3] == ((ctx->sig_len - 4) & 0xff))
		return 0;
		if (pkcs7[1] == 0x80)
		return 0;
		if (pkcs7[1] > 0x82)
		return -EMSGSIZE;
		}

		pr_debug("Signature data not PKCS#7\n");
		return -ELIBBAD;
		}

		/*
		* Compare two sections for canonicalisation.
		*/
		static int pefile_compare_shdrs(const void a, const void b)
		{
		const struct section_header *shdra = a;
		const struct section_header *shdrb = b;
		int rc;

		if (shdra->data_addr > shdrb->data_addr)
		return 1;
		if (shdrb->data_addr > shdra->data_addr)
		return -1;

		if (shdra->virtual_address > shdrb->virtual_address)
		return 1;
		if (shdrb->virtual_address > shdra->virtual_address)
		return -1;

		rc = strcmp(shdra->name, shdrb->name);
		if (rc != 0)
		return rc;

		if (shdra->virtual_size > shdrb->virtual_size)
		return 1;
		if (shdrb->virtual_size > shdra->virtual_size)
		return -1;

		if (shdra->raw_data_size > shdrb->raw_data_size)
		return 1;
		if (shdrb->raw_data_size > shdra->raw_data_size)
		return -1;

		return 0;
		}

		/*
		* Load the contents of the PE binary into the digest, leaving out the image
		* checksum and the certificate data block.
		*/
		static int pefile_digest_pe_contents(const void *pebuf, unsigned int pelen,
		struct pefile_context *ctx,
		struct shash_desc *desc)
		{
		unsigned *canon, tmp, loop, i, hashed_bytes;
		int ret;

		/* Digest the header and data directory, but leave out the image
		* checksum and the data dirent for the signature.
		*/
		ret = crypto_shash_update(desc, pebuf, ctx->image_checksum_offset);
		if (ret < 0)
		return ret;

		tmp = ctx->image_checksum_offset + sizeof(uint32_t);
		ret = crypto_shash_update(desc, pebuf + tmp,
		ctx->cert_dirent_offset - tmp);
		if (ret < 0)
		return ret;

		tmp = ctx->cert_dirent_offset + sizeof(struct data_dirent);
		ret = crypto_shash_update(desc, pebuf + tmp, ctx->header_size - tmp);
		if (ret < 0)
		return ret;

		canon = kcalloc(ctx->n_sections, sizeof(unsigned), GFP_KERNEL);
		if (!canon)
		return -ENOMEM;

		/* We have to canonicalise the section table, so we perform an
		* insertion sort.
		*/
		canon[0] = 0;
		for (loop = 1; loop < ctx->n_sections; loop++) {
		for (i = 0; i < loop; i++) {
		if (pefile_compare_shdrs(&ctx->secs[canon[i]],
		&ctx->secs[loop]) > 0) {
		memmove(&canon[i + 1], &canon[i],
		(loop - i) * sizeof(canon[0]));
		break;
		}
		}
		canon[i] = loop;
		}

		hashed_bytes = ctx->header_size;
		for (loop = 0; loop < ctx->n_sections; loop++) {
		i = canon[loop];
		if (ctx->secs[i].raw_data_size == 0)
		continue;
		ret = crypto_shash_update(desc,
		pebuf + ctx->secs[i].data_addr,
		ctx->secs[i].raw_data_size);
		if (ret < 0) {
		kfree(canon);
		return ret;
		}
		hashed_bytes += ctx->secs[i].raw_data_size;
		}
		kfree(canon);

		if (pelen > hashed_bytes) {
		tmp = hashed_bytes + ctx->certs_size;
		ret = crypto_shash_update(desc,
		pebuf + hashed_bytes,
		pelen - tmp);
		if (ret < 0)
		return ret;
		}

		return 0;
		}

		/*
		* Digest the contents of the PE binary, leaving out the image checksum and the
		* certificate data block.
		*/
		static int pefile_digest_pe(const void *pebuf, unsigned int pelen,
		struct pefile_context *ctx)
		{
		struct crypto_shash *tfm;
		struct shash_desc *desc;
		size_t digest_size, desc_size;
		void *digest;
		int ret;

		kenter(",%u", ctx->digest_algo);

		/* Allocate the hashing algorithm we're going to need and find out how
		* big the hash operational data will be.
		*/
		tfm = crypto_alloc_shash(hash_algo_name[ctx->digest_algo], 0, 0);
		if (IS_ERR(tfm))
		return (PTR_ERR(tfm) == -ENOENT) ? -ENOPKG : PTR_ERR(tfm);

		desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
		digest_size = crypto_shash_digestsize(tfm);

		if (digest_size != ctx->digest_len) {
		pr_debug("Digest size mismatch (%zx != %x)\n",
		digest_size, ctx->digest_len);
		ret = -EBADMSG;
		goto error_no_desc;
		}
		pr_debug("Digest: desc=%zu size=%zu\n", desc_size, digest_size);

		ret = -ENOMEM;
		desc = kzalloc(desc_size + digest_size, GFP_KERNEL);
		if (!desc)
		goto error_no_desc;

		desc->tfm = tfm;
		desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
		ret = crypto_shash_init(desc);
		if (ret < 0)
		goto error;

		ret = pefile_digest_pe_contents(pebuf, pelen, ctx, desc);
		if (ret < 0)
		goto error;

		digest = (void *)desc + desc_size;
		ret = crypto_shash_final(desc, digest);
		if (ret < 0)
		goto error;

		pr_debug("Digest calc = [%*ph]\n", ctx->digest_len, digest);

		/* Check that the PE file digest matches that in the MSCODE part of the
		* PKCS#7 certificate.
		*/
		if (memcmp(digest, ctx->digest, ctx->digest_len) != 0) {
		pr_debug("Digest mismatch\n");
		ret = -EKEYREJECTED;
		} else {
		pr_debug("The digests match!\n");
		}

		error:
		kfree(desc);
		error_no_desc:
		crypto_free_shash(tfm);
		kleave(" = %d", ret);
		return ret;
		}

		/**
		* verify_pefile_signature - Verify the signature on a PE binary image
		* @pebuf: Buffer containing the PE binary image
		* @pelen: Length of the binary image
		* @trust_keyring: Signing certificates to use as starting points
		* @_trusted: Set to true if trustworth, false otherwise
		*
		* Validate that the certificate chain inside the PKCS#7 message inside the PE
		* binary image intersects keys we already know and trust.
		*
		* Returns, in order of descending priority:
		*
		* (*) -ELIBBAD if the image cannot be parsed, or:
		*
		* (*) -EKEYREJECTED if a signature failed to match for which we have a valid
		* key, or:
		*
		* (*) 0 if at least one signature chain intersects with the keys in the trust
		* keyring, or:
		*
		* (*) -ENOPKG if a suitable crypto module couldn't be found for a check on a
		* chain.
		*
		* (*) -ENOKEY if we couldn't find a match for any of the signature chains in
		* the message.
		*
		* May also return -ENOMEM.
		*/
		int verify_pefile_signature(const void *pebuf, unsigned pelen,
		struct key trusted_keyring, bool _trusted)
		{
		struct pkcs7_message *pkcs7;
		struct pefile_context ctx;
		const void *data;
		size_t datalen;
		int ret;

		kenter("");

		memset(&ctx, 0, sizeof(ctx));
		ret = pefile_parse_binary(pebuf, pelen, &ctx);
		if (ret < 0)
		return ret;

		ret = pefile_strip_sig_wrapper(pebuf, &ctx);
		if (ret < 0)
		return ret;

		pkcs7 = pkcs7_parse_message(pebuf + ctx.sig_offset, ctx.sig_len);
		if (IS_ERR(pkcs7))
		return PTR_ERR(pkcs7);
		ctx.pkcs7 = pkcs7;

		ret = pkcs7_get_content_data(ctx.pkcs7, &data, &datalen, false);
		if (ret < 0 \|\| datalen == 0) {
		pr_devel("PKCS#7 message does not contain data\n");
		ret = -EBADMSG;
		goto error;
		}

		ret = mscode_parse(&ctx);
		if (ret < 0)
		goto error;

		pr_debug("Digest: %u [%*ph]\n",
		ctx.digest_len, ctx.digest_len, ctx.digest);

		/* Generate the digest and check against the PKCS7 certificate
		* contents.
		*/
		ret = pefile_digest_pe(pebuf, pelen, &ctx);
		if (ret < 0)
		goto error;

		ret = pkcs7_verify(pkcs7);
		if (ret < 0)
		goto error;

		ret = pkcs7_validate_trust(pkcs7, trusted_keyring, _trusted);

		error:
		pkcs7_free_message(ctx.pkcs7);
		return ret;
		}