In MS authenticode, pkcs7 should have data in its contentInfo field. This data is tagged with SpcIndirectData type and, for a signed PE image, provides a image's message digest as SpcPeImageData.

This parser is used in image authentication to parse the field and retrieve a message digest.

Imported from linux v5.19-rc, crypto/asymmetric_keys/mscode*. Checkpatch.pl generates tones of warnings, but those are not fixed for the sake of maintainability (importing from another source).

Signed-off-by: AKASHI Takahiro takahiro.akashi@linaro.org --- include/crypto/mscode.h | 43 ++++++++++++ lib/crypto/Kconfig | 9 +++ lib/crypto/Makefile | 12 ++++ lib/crypto/mscode.asn1 | 28 ++++++++ lib/crypto/mscode_parser.c | 135 +++++++++++++++++++++++++++++++++++++ 5 files changed, 227 insertions(+) create mode 100644 include/crypto/mscode.h create mode 100644 lib/crypto/mscode.asn1 create mode 100644 lib/crypto/mscode_parser.c

diff --git a/include/crypto/mscode.h b/include/crypto/mscode.h new file mode 100644 index 000000000000..551058b96e60 --- /dev/null +++ b/include/crypto/mscode.h @@ -0,0 +1,43 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* PE Binary parser bits + * + * Copyright (C) 2014 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include <crypto/pkcs7.h> +#ifndef __UBOOT__ +#include <crypto/hash_info.h> +#endif + +struct pefile_context { +#ifndef __UBOOT__ + unsigned header_size; + unsigned image_checksum_offset; + unsigned cert_dirent_offset; + unsigned n_data_dirents; + unsigned n_sections; + unsigned certs_size; + unsigned sig_offset; + unsigned sig_len; + const struct section_header *secs; +#endif + + /* PKCS#7 MS Individual Code Signing content */ + const void *digest; /* Digest */ + unsigned digest_len; /* Digest length */ + const char *digest_algo; /* Digest algorithm */ +}; + +#ifndef __UBOOT__ +#define kenter(FMT, ...) \ + pr_devel("==> %s("FMT")\n", __func__, ##__VA_ARGS__) +#define kleave(FMT, ...) \ + pr_devel("<== %s()"FMT"\n", __func__, ##__VA_ARGS__) +#endif + +/* + * mscode_parser.c + */ +extern int mscode_parse(void *_ctx, const void *content_data, size_t data_len, + size_t asn1hdrlen); diff --git a/lib/crypto/Kconfig b/lib/crypto/Kconfig index 1c04a7ec5f48..c3f563b2e174 100644 --- a/lib/crypto/Kconfig +++ b/lib/crypto/Kconfig @@ -82,4 +82,13 @@ config PKCS7_MESSAGE_PARSER config PKCS7_VERIFY bool

+config MSCODE_PARSER + bool "MS authenticode parser" + select ASN1_DECODER + select ASN1_COMPILER + select OID_REGISTRY + help + This option provides support for parsing MicroSoft's Authenticode + in pkcs7 message. + endif # ASYMMETRIC_KEY_TYPE diff --git a/lib/crypto/Makefile b/lib/crypto/Makefile index 6792b1d4f007..bec1bc95a658 100644 --- a/lib/crypto/Makefile +++ b/lib/crypto/Makefile @@ -55,3 +55,15 @@ obj-$(CONFIG_$(SPL_)PKCS7_VERIFY) += pkcs7_verify.o

$(obj)/pkcs7_parser.o: $(obj)/pkcs7.asn1.h $(obj)/pkcs7.asn1.o: $(obj)/pkcs7.asn1.c $(obj)/pkcs7.asn1.h + +# +# Signed PE binary-wrapped key handling +# +obj-$(CONFIG_$(SPL_)MSCODE_PARSER) += mscode.o + +mscode-y := \ + mscode_parser.o \ + mscode.asn1.o + +$(obj)/mscode_parser.o: $(obj)/mscode.asn1.h $(obj)/mscode.asn1.h +$(obj)/mscode.asn1.o: $(obj)/mscode.asn1.c $(obj)/mscode.asn1.h diff --git a/lib/crypto/mscode.asn1 b/lib/crypto/mscode.asn1 new file mode 100644 index 000000000000..6d09ba48c41c --- /dev/null +++ b/lib/crypto/mscode.asn1 @@ -0,0 +1,28 @@ +--- 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 +} diff --git a/lib/crypto/mscode_parser.c b/lib/crypto/mscode_parser.c new file mode 100644 index 000000000000..90d5b37a6cf2 --- /dev/null +++ b/lib/crypto/mscode_parser.c @@ -0,0 +1,135 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* Parse a Microsoft Individual Code Signing blob + * + * Copyright (C) 2014 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#define pr_fmt(fmt) "MSCODE: "fmt +#include <linux/kernel.h> +#ifndef __UBOOT__ +#include <linux/slab.h> +#endif +#include <linux/err.h> +#include <linux/oid_registry.h> +#include <crypto/pkcs7.h> +#ifdef __UBOOT__ +#include <crypto/mscode.h> +#else +#include "verify_pefile.h" +#endif +#include "mscode.asn1.h" + +/* + * Parse a Microsoft Individual Code Signing blob + */ +int mscode_parse(void *_ctx, const void *content_data, size_t data_len, + size_t asn1hdrlen) +{ + struct pefile_context *ctx = _ctx; + + content_data -= asn1hdrlen; + data_len += asn1hdrlen; + 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 = "md4"; + break; + case OID_md5: + ctx->digest_algo = "md5"; + break; + case OID_sha1: + ctx->digest_algo = "sha1"; + break; + case OID_sha256: + ctx->digest_algo = "sha256"; + break; + case OID_sha384: + ctx->digest_algo = "sha384"; + break; + case OID_sha512: + ctx->digest_algo = "sha512"; + break; + case OID_sha224: + ctx->digest_algo = "sha224"; + 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 = kmemdup(value, vlen, GFP_KERNEL); + if (!ctx->digest) + return -ENOMEM; + + ctx->digest_len = vlen; + + return 0; +}

Now We are migrating from EFI_PRINT() to log macro's.

Signed-off-by: AKASHI Takahiro takahiro.akashi@linaro.org --- lib/efi_loader/efi_image_loader.c | 54 +++++++++++++++---------------- 1 file changed, 27 insertions(+), 27 deletions(-)

diff --git a/lib/efi_loader/efi_image_loader.c b/lib/efi_loader/efi_image_loader.c index 961139888504..fe8e4a89082c 100644 --- a/lib/efi_loader/efi_image_loader.c +++ b/lib/efi_loader/efi_image_loader.c @@ -238,7 +238,7 @@ efi_status_t efi_image_region_add(struct efi_image_regions *regs, int i, j;

if (regs->num >= regs->max) { - EFI_PRINT("%s: no more room for regions\n", __func__); + log_err("%s: no more room for regions\n", __func__); return EFI_OUT_OF_RESOURCES; }

@@ -263,7 +263,7 @@ efi_status_t efi_image_region_add(struct efi_image_regions *regs, }

/* new data overlapping registered region */ - EFI_PRINT("%s: new region already part of another\n", __func__); + log_err("%s: new region already part of another\n", __func__); return EFI_INVALID_PARAMETER; }

@@ -434,8 +434,8 @@ bool efi_image_parse(void *efi, size_t len, struct efi_image_regions **regp, bytes_hashed = opt->SizeOfHeaders; align = opt->FileAlignment; } else { - EFI_PRINT("%s: Invalid optional header magic %x\n", __func__, - nt->OptionalHeader.Magic); + log_err("%s: Invalid optional header magic %x\n", __func__, + nt->OptionalHeader.Magic); goto err; }

@@ -445,7 +445,7 @@ bool efi_image_parse(void *efi, size_t len, struct efi_image_regions **regp, nt->FileHeader.SizeOfOptionalHeader); sorted = calloc(sizeof(IMAGE_SECTION_HEADER *), num_sections); if (!sorted) { - EFI_PRINT("%s: Out of memory\n", __func__); + log_err("%s: Out of memory\n", __func__); goto err; }

@@ -464,7 +464,7 @@ bool efi_image_parse(void *efi, size_t len, struct efi_image_regions **regp, efi_image_region_add(regs, efi + sorted[i]->PointerToRawData, efi + sorted[i]->PointerToRawData + size, 0); - EFI_PRINT("section[%d](%s): raw: 0x%x-0x%x, virt: %x-%x\n", + log_debug("section[%d](%s): raw: 0x%x-0x%x, virt: %x-%x\n", i, sorted[i]->Name, sorted[i]->PointerToRawData, sorted[i]->PointerToRawData + size, @@ -478,7 +478,7 @@ bool efi_image_parse(void *efi, size_t len, struct efi_image_regions **regp,

/* 3. Extra data excluding Certificates Table */ if (bytes_hashed + authsz < len) { - EFI_PRINT("extra data for hash: %zu\n", + log_debug("extra data for hash: %zu\n", len - (bytes_hashed + authsz)); efi_image_region_add(regs, efi + bytes_hashed, efi + len - authsz, 0); @@ -487,18 +487,18 @@ bool efi_image_parse(void *efi, size_t len, struct efi_image_regions **regp, /* Return Certificates Table */ if (authsz) { if (len < authoff + authsz) { - EFI_PRINT("%s: Size for auth too large: %u >= %zu\n", - __func__, authsz, len - authoff); + log_err("%s: Size for auth too large: %u >= %zu\n", + __func__, authsz, len - authoff); goto err; } if (authsz < sizeof(*auth)) { - EFI_PRINT("%s: Size for auth too small: %u < %zu\n", - __func__, authsz, sizeof(*auth)); + log_err("%s: Size for auth too small: %u < %zu\n", + __func__, authsz, sizeof(*auth)); goto err; } *auth = efi + authoff; *auth_len = authsz; - EFI_PRINT("WIN_CERTIFICATE: 0x%x, size: 0x%x\n", authoff, + log_debug("WIN_CERTIFICATE: 0x%x, size: 0x%x\n", authoff, authsz); } else { *auth = NULL; @@ -549,7 +549,7 @@ static bool efi_image_authenticate(void *efi, size_t efi_size) size_t auth_size; bool ret = false;

- EFI_PRINT("%s: Enter, %d\n", __func__, ret); + log_debug("%s: Enter, %d\n", __func__, ret);

if (!efi_secure_boot_enabled()) return true; @@ -560,7 +560,7 @@ static bool efi_image_authenticate(void *efi, size_t efi_size)

if (!efi_image_parse(new_efi, efi_size, &regs, &wincerts, &wincerts_len)) { - EFI_PRINT("Parsing PE executable image failed\n"); + log_err("Parsing PE executable image failed\n"); goto out; }

@@ -569,18 +569,18 @@ static bool efi_image_authenticate(void *efi, size_t efi_size) */ db = efi_sigstore_parse_sigdb(u"db"); if (!db) { - EFI_PRINT("Getting signature database(db) failed\n"); + log_err("Getting signature database(db) failed\n"); goto out; }

dbx = efi_sigstore_parse_sigdb(u"dbx"); if (!dbx) { - EFI_PRINT("Getting signature database(dbx) failed\n"); + log_err("Getting signature database(dbx) failed\n"); goto out; }

if (efi_signature_lookup_digest(regs, dbx, true)) { - EFI_PRINT("Image's digest was found in "dbx"\n"); + log_debug("Image's digest was found in "dbx"\n"); goto out; }

@@ -602,12 +602,12 @@ static bool efi_image_authenticate(void *efi, size_t efi_size) break;

if (wincert->dwLength <= sizeof(*wincert)) { - EFI_PRINT("dwLength too small: %u < %zu\n", + log_debug("dwLength too small: %u < %zu\n", wincert->dwLength, sizeof(*wincert)); continue; }

- EFI_PRINT("WIN_CERTIFICATE_TYPE: 0x%x\n", + log_debug("WIN_CERTIFICATE_TYPE: 0x%x\n", wincert->wCertificateType);

auth = (u8 *)wincert + sizeof(*wincert); @@ -617,12 +617,12 @@ static bool efi_image_authenticate(void *efi, size_t efi_size) break;

if (auth_size <= sizeof(efi_guid_t)) { - EFI_PRINT("dwLength too small: %u < %zu\n", + log_debug("dwLength too small: %u < %zu\n", wincert->dwLength, sizeof(*wincert)); continue; } if (guidcmp(auth, &efi_guid_cert_type_pkcs7)) { - EFI_PRINT("Certificate type not supported: %pUs\n", + log_debug("Certificate type not supported: %pUs\n", auth); ret = false; goto out; @@ -632,14 +632,14 @@ static bool efi_image_authenticate(void *efi, size_t efi_size) auth_size -= sizeof(efi_guid_t); } else if (wincert->wCertificateType != WIN_CERT_TYPE_PKCS_SIGNED_DATA) { - EFI_PRINT("Certificate type not supported\n"); + log_debug("Certificate type not supported\n"); ret = false; goto out; }

msg = pkcs7_parse_message(auth, auth_size); if (IS_ERR(msg)) { - EFI_PRINT("Parsing image's signature failed\n"); + log_err("Parsing image's signature failed\n"); msg = NULL; continue; } @@ -666,13 +666,13 @@ static bool efi_image_authenticate(void *efi, size_t efi_size) /* try black-list first */ if (efi_signature_verify_one(regs, msg, dbx)) { ret = false; - EFI_PRINT("Signature was rejected by "dbx"\n"); + log_debug("Signature was rejected by "dbx"\n"); goto out; }

if (!efi_signature_check_signers(msg, dbx)) { ret = false; - EFI_PRINT("Signer(s) in "dbx"\n"); + log_debug("Signer(s) in "dbx"\n"); goto out; }

@@ -682,7 +682,7 @@ static bool efi_image_authenticate(void *efi, size_t efi_size) continue; }

- EFI_PRINT("Signature was not verified by "db"\n"); + log_debug("Signature was not verified by "db"\n"); }

@@ -698,7 +698,7 @@ out: if (new_efi != efi) free(new_efi);

- EFI_PRINT("%s: Exit, %d\n", __func__, ret); + log_debug("%s: Exit, %d\n", __func__, ret); return ret; } #else

In this test case, a image binary, helloworld.efi.signed, is willfully modified to print a corrupted message while the signature itself is unchanged.

This binary must be rejected under secure boot mode.

Signed-off-by: AKASHI Takahiro takahiro.akashi@linaro.org --- test/py/tests/test_efi_secboot/conftest.py | 3 ++ test/py/tests/test_efi_secboot/forge_image.sh | 5 +++ test/py/tests/test_efi_secboot/test_signed.py | 35 +++++++++++++++++++ 3 files changed, 43 insertions(+) create mode 100644 test/py/tests/test_efi_secboot/forge_image.sh

diff --git a/test/py/tests/test_efi_secboot/conftest.py b/test/py/tests/test_efi_secboot/conftest.py index 8a53dabe5414..db6b8d301f85 100644 --- a/test/py/tests/test_efi_secboot/conftest.py +++ b/test/py/tests/test_efi_secboot/conftest.py @@ -105,6 +105,9 @@ def efi_boot_env(request, u_boot_config): # Sign already-signed image with another key check_call('cd %s; sbsign --key db1.key --cert db1.crt --output helloworld.efi.signed_2sigs helloworld.efi.signed' % mnt_point, shell=True) + # Create a corrupted signed image + check_call('cd %s; sh %s/test/py/tests/test_efi_secboot/forge_image.sh helloworld.efi.signed helloworld_forged.efi.signed' + % (mnt_point, u_boot_config.source_dir), shell=True) # Digest image check_call('cd %s; %shash-to-efi-sig-list helloworld.efi db_hello.hash; %ssign-efi-sig-list -t "2020-04-07" -c KEK.crt -k KEK.key db db_hello.hash db_hello.auth' % (mnt_point, EFITOOLS_PATH, EFITOOLS_PATH), diff --git a/test/py/tests/test_efi_secboot/forge_image.sh b/test/py/tests/test_efi_secboot/forge_image.sh new file mode 100644 index 000000000000..2465d10fa7b8 --- /dev/null +++ b/test/py/tests/test_efi_secboot/forge_image.sh @@ -0,0 +1,5 @@ +# SPDX-License-Identifier: GPL-2.0-or-later +#!/bin/sh + +replace_exp="s/H\0e\0l\0l\0o\0/h\0E\0L\0L\0O\0/g" +perl -p -e ${replace_exp} < $1 > $2 diff --git a/test/py/tests/test_efi_secboot/test_signed.py b/test/py/tests/test_efi_secboot/test_signed.py index 30b3fa4e701e..ca52e853d8f8 100644 --- a/test/py/tests/test_efi_secboot/test_signed.py +++ b/test/py/tests/test_efi_secboot/test_signed.py @@ -334,3 +334,38 @@ class TestEfiSignedImage(object): 'efidebug test bootmgr']) assert ''HELLO' failed' in ''.join(output) assert 'efi_start_image() returned: 26' in ''.join(output) + + def test_efi_signed_image_auth8(self, u_boot_console, efi_boot_env): + """ + Test Case 8 - Secure boot is in force, + Same as Test Case 2 but the image binary to be loaded + was willfully modified (forged) + Must be rejected. + """ + u_boot_console.restart_uboot() + disk_img = efi_boot_env + with u_boot_console.log.section('Test Case 8a'): + # Test Case 8a, Secure boot is not yet forced + output = u_boot_console.run_command_list([ + 'host bind 0 %s' % disk_img, + 'efidebug boot add -b 1 HELLO1 host 0:1 /helloworld_forged.efi.signed -s ""', + 'efidebug boot next 1', + 'efidebug test bootmgr']) + assert('hELLO, world!' in ''.join(output)) + + with u_boot_console.log.section('Test Case 8b'): + # Test Case 8b, Install signature database and verify the image + output = u_boot_console.run_command_list([ + 'fatload host 0:1 4000000 db.auth', + 'setenv -e -nv -bs -rt -at -i 4000000:$filesize db', + 'fatload host 0:1 4000000 KEK.auth', + 'setenv -e -nv -bs -rt -at -i 4000000:$filesize KEK', + 'fatload host 0:1 4000000 PK.auth', + 'setenv -e -nv -bs -rt -at -i 4000000:$filesize PK']) + assert 'Failed to set EFI variable' not in ''.join(output) + output = u_boot_console.run_command_list([ + 'efidebug boot next 1', + 'efidebug test bootmgr']) + assert(not 'hELLO, world!' in ''.join(output)) + assert(''HELLO1' failed' in ''.join(output)) + assert('efi_start_image() returned: 26' in ''.join(output))