From 201b8068f35385c1c7794f24d0a3ac427210f241 Mon Sep 17 00:00:00 2001 From: Sughosh Ganu Date: Wed, 30 Dec 2020 19:27:07 +0530 Subject: efi_loader: Make the pkcs7 header parsing function an extern The pkcs7 header parsing functionality is pretty generic, and can be used by other features like capsule authentication. Make the function an extern, also changing it's name to efi_parse_pkcs7_header Signed-off-by: Sughosh Ganu --- lib/efi_loader/efi_signature.c | 85 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 85 insertions(+) (limited to 'lib/efi_loader/efi_signature.c') diff --git a/lib/efi_loader/efi_signature.c b/lib/efi_loader/efi_signature.c index 79dee27421..9ab071b611 100644 --- a/lib/efi_loader/efi_signature.c +++ b/lib/efi_loader/efi_signature.c @@ -27,6 +27,91 @@ const efi_guid_t efi_guid_cert_x509_sha256 = EFI_CERT_X509_SHA256_GUID; const efi_guid_t efi_guid_cert_type_pkcs7 = EFI_CERT_TYPE_PKCS7_GUID; #ifdef CONFIG_EFI_SECURE_BOOT +static u8 pkcs7_hdr[] = { + /* SEQUENCE */ + 0x30, 0x82, 0x05, 0xc7, + /* OID: pkcs7-signedData */ + 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x07, 0x02, + /* Context Structured? */ + 0xa0, 0x82, 0x05, 0xb8, +}; + +/** + * efi_parse_pkcs7_header - parse a signature in payload + * @buf: Pointer to payload's value + * @buflen: Length of @buf + * @tmpbuf: Pointer to temporary buffer + * + * Parse a signature embedded in payload's value and instantiate + * a pkcs7_message structure. Since pkcs7_parse_message() accepts only + * pkcs7's signedData, some header needed be prepended for correctly + * parsing authentication data + * A temporary buffer will be allocated if needed, and it should be + * kept valid during the authentication because some data in the buffer + * will be referenced by efi_signature_verify(). + * + * Return: Pointer to pkcs7_message structure on success, NULL on error + */ +struct pkcs7_message *efi_parse_pkcs7_header(const void *buf, + size_t buflen, + u8 **tmpbuf) +{ + u8 *ebuf; + size_t ebuflen, len; + struct pkcs7_message *msg; + + /* + * This is the best assumption to check if the binary is + * already in a form of pkcs7's signedData. + */ + if (buflen > sizeof(pkcs7_hdr) && + !memcmp(&((u8 *)buf)[4], &pkcs7_hdr[4], 11)) { + msg = pkcs7_parse_message(buf, buflen); + if (IS_ERR(msg)) + return NULL; + return msg; + } + + /* + * Otherwise, we should add a dummy prefix sequence for pkcs7 + * message parser to be able to process. + * NOTE: EDK2 also uses similar hack in WrapPkcs7Data() + * in CryptoPkg/Library/BaseCryptLib/Pk/CryptPkcs7VerifyCommon.c + * TODO: + * The header should be composed in a more refined manner. + */ + EFI_PRINT("Makeshift prefix added to authentication data\n"); + ebuflen = sizeof(pkcs7_hdr) + buflen; + if (ebuflen <= 0x7f) { + EFI_PRINT("Data is too short\n"); + return NULL; + } + + ebuf = malloc(ebuflen); + if (!ebuf) { + EFI_PRINT("Out of memory\n"); + return NULL; + } + + memcpy(ebuf, pkcs7_hdr, sizeof(pkcs7_hdr)); + memcpy(ebuf + sizeof(pkcs7_hdr), buf, buflen); + len = ebuflen - 4; + ebuf[2] = (len >> 8) & 0xff; + ebuf[3] = len & 0xff; + len = ebuflen - 0x13; + ebuf[0x11] = (len >> 8) & 0xff; + ebuf[0x12] = len & 0xff; + + msg = pkcs7_parse_message(ebuf, ebuflen); + + if (IS_ERR(msg)) { + free(ebuf); + return NULL; + } + + *tmpbuf = ebuf; + return msg; +} /** * efi_hash_regions - calculate a hash value -- cgit v1.2.3 From b4f20a5d83f0b8a5c30128966eabe68748631e66 Mon Sep 17 00:00:00 2001 From: Sughosh Ganu Date: Wed, 30 Dec 2020 19:27:08 +0530 Subject: efi_loader: Re-factor code to build the signature store from efi signature list The efi_sigstore_parse_sigdb function reads the uefi authenticated variable, stored in the signature database format and builds the signature store structure. Factor out the code for building the signature store. This can then be used by the capsule authentication routine to build the signature store even when the signature database is not stored as an uefi authenticated variable Signed-off-by: Sughosh Ganu --- include/efi_loader.h | 2 + lib/efi_loader/efi_signature.c | 103 ++++++++++++++++++++++++----------------- 2 files changed, 63 insertions(+), 42 deletions(-) (limited to 'lib/efi_loader/efi_signature.c') diff --git a/include/efi_loader.h b/include/efi_loader.h index f1dfb1d33f..7fd65eeb8d 100644 --- a/include/efi_loader.h +++ b/include/efi_loader.h @@ -813,6 +813,8 @@ efi_status_t efi_image_region_add(struct efi_image_regions *regs, int nocheck); void efi_sigstore_free(struct efi_signature_store *sigstore); +struct efi_signature_store *efi_build_signature_store(void *sig_list, + efi_uintn_t size); struct efi_signature_store *efi_sigstore_parse_sigdb(u16 *name); bool efi_secure_boot_enabled(void); diff --git a/lib/efi_loader/efi_signature.c b/lib/efi_loader/efi_signature.c index 9ab071b611..87525bdc80 100644 --- a/lib/efi_loader/efi_signature.c +++ b/lib/efi_loader/efi_signature.c @@ -736,6 +736,63 @@ err: return NULL; } +/** + * efi_sigstore_parse_sigdb - parse the signature list and populate + * the signature store + * + * @sig_list: Pointer to the signature list + * @size: Size of the signature list + * + * Parse the efi signature list and instantiate a signature store + * structure. + * + * Return: Pointer to signature store on success, NULL on error + */ +struct efi_signature_store *efi_build_signature_store(void *sig_list, + efi_uintn_t size) +{ + struct efi_signature_list *esl; + struct efi_signature_store *sigstore = NULL, *siglist; + + esl = sig_list; + while (size > 0) { + /* List must exist if there is remaining data. */ + if (size < sizeof(*esl)) { + EFI_PRINT("Signature list in wrong format\n"); + goto err; + } + + if (size < esl->signature_list_size) { + EFI_PRINT("Signature list in wrong format\n"); + goto err; + } + + /* Parse a single siglist. */ + siglist = efi_sigstore_parse_siglist(esl); + if (!siglist) { + EFI_PRINT("Parsing of signature list of failed\n"); + goto err; + } + + /* Append siglist */ + siglist->next = sigstore; + sigstore = siglist; + + /* Next */ + size -= esl->signature_list_size; + esl = (void *)esl + esl->signature_list_size; + } + free(sig_list); + + return sigstore; + +err: + efi_sigstore_free(sigstore); + free(sig_list); + + return NULL; +} + /** * efi_sigstore_parse_sigdb - parse a signature database variable * @name: Variable's name @@ -747,8 +804,7 @@ err: */ struct efi_signature_store *efi_sigstore_parse_sigdb(u16 *name) { - struct efi_signature_store *sigstore = NULL, *siglist; - struct efi_signature_list *esl; + struct efi_signature_store *sigstore = NULL; const efi_guid_t *vendor; void *db; efi_uintn_t db_size; @@ -784,47 +840,10 @@ struct efi_signature_store *efi_sigstore_parse_sigdb(u16 *name) ret = EFI_CALL(efi_get_variable(name, vendor, NULL, &db_size, db)); if (ret != EFI_SUCCESS) { EFI_PRINT("Getting variable, %ls, failed\n", name); - goto err; - } - - /* Parse siglist list */ - esl = db; - while (db_size > 0) { - /* List must exist if there is remaining data. */ - if (db_size < sizeof(*esl)) { - EFI_PRINT("variable, %ls, in wrong format\n", name); - goto err; - } - - if (db_size < esl->signature_list_size) { - EFI_PRINT("variable, %ls, in wrong format\n", name); - goto err; - } - - /* Parse a single siglist. */ - siglist = efi_sigstore_parse_siglist(esl); - if (!siglist) { - EFI_PRINT("Parsing signature list of %ls failed\n", - name); - goto err; - } - - /* Append siglist */ - siglist->next = sigstore; - sigstore = siglist; - - /* Next */ - db_size -= esl->signature_list_size; - esl = (void *)esl + esl->signature_list_size; + free(db); + return NULL; } - free(db); - - return sigstore; -err: - efi_sigstore_free(sigstore); - free(db); - - return NULL; + return efi_build_signature_store(db, db_size); } #endif /* CONFIG_EFI_SECURE_BOOT */ -- cgit v1.2.3 From 04be98bd6bcfccf3ab028fda0ca962dd00f61260 Mon Sep 17 00:00:00 2001 From: Sughosh Ganu Date: Wed, 30 Dec 2020 19:27:09 +0530 Subject: efi: capsule: Add support for uefi capsule authentication Add support for authenticating uefi capsules. Most of the signature verification functionality is shared with the uefi secure boot feature. The root certificate containing the public key used for the signature verification is stored as part of the device tree blob. The root certificate is stored as an efi signature list(esl) file -- this file contains the x509 certificate which is the root certificate. Signed-off-by: Sughosh Ganu --- board/emulation/common/Makefile | 1 + board/emulation/common/qemu_capsule.c | 48 +++++++++++++ include/efi_api.h | 18 +++++ include/efi_loader.h | 6 ++ lib/efi_loader/Kconfig | 17 +++++ lib/efi_loader/efi_capsule.c | 122 ++++++++++++++++++++++++++++++++++ lib/efi_loader/efi_signature.c | 4 +- 7 files changed, 214 insertions(+), 2 deletions(-) create mode 100644 board/emulation/common/qemu_capsule.c (limited to 'lib/efi_loader/efi_signature.c') diff --git a/board/emulation/common/Makefile b/board/emulation/common/Makefile index c5b452e7e3..7ed447a69d 100644 --- a/board/emulation/common/Makefile +++ b/board/emulation/common/Makefile @@ -2,3 +2,4 @@ obj-$(CONFIG_SYS_MTDPARTS_RUNTIME) += qemu_mtdparts.o obj-$(CONFIG_SET_DFU_ALT_INFO) += qemu_dfu.o +obj-$(CONFIG_EFI_CAPSULE_FIRMWARE_MANAGEMENT) += qemu_capsule.o diff --git a/board/emulation/common/qemu_capsule.c b/board/emulation/common/qemu_capsule.c new file mode 100644 index 0000000000..f1d403501a --- /dev/null +++ b/board/emulation/common/qemu_capsule.c @@ -0,0 +1,48 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Copyright (c) 2020 Linaro Limited + */ + +#include +#include +#include +#include +#include + +DECLARE_GLOBAL_DATA_PTR; + +int efi_get_public_key_data(void **pkey, efi_uintn_t *pkey_len) +{ + const void *fdt_blob = gd->fdt_blob; + const void *blob; + const char *cnode_name = "capsule-key"; + const char *snode_name = "signature"; + int sig_node; + int len; + + sig_node = fdt_subnode_offset(fdt_blob, 0, snode_name); + if (sig_node < 0) { + EFI_PRINT("Unable to get signature node offset\n"); + return -FDT_ERR_NOTFOUND; + } + + blob = fdt_getprop(fdt_blob, sig_node, cnode_name, &len); + + if (!blob || len < 0) { + EFI_PRINT("Unable to get capsule-key value\n"); + *pkey = NULL; + *pkey_len = 0; + return -FDT_ERR_NOTFOUND; + } + + *pkey = (void *)blob; + *pkey_len = len; + + return 0; +} + +bool efi_capsule_auth_enabled(void) +{ + return env_get("capsule_authentication_enabled") != NULL ? + true : false; +} diff --git a/include/efi_api.h b/include/efi_api.h index e82d4ca9ff..ecb43a0607 100644 --- a/include/efi_api.h +++ b/include/efi_api.h @@ -1812,6 +1812,24 @@ struct efi_variable_authentication_2 { struct win_certificate_uefi_guid auth_info; } __attribute__((__packed__)); +/** + * efi_firmware_image_authentication - Capsule authentication method + * descriptor + * + * This structure describes an authentication information for + * a capsule with IMAGE_ATTRIBUTE_AUTHENTICATION_REQUIRED set + * and should be included as part of the capsule. + * Only EFI_CERT_TYPE_PKCS7_GUID is accepted. + * + * @monotonic_count: Count to prevent replay + * @auth_info: Authentication info + */ +struct efi_firmware_image_authentication { + uint64_t monotonic_count; + struct win_certificate_uefi_guid auth_info; +} __attribute__((__packed__)); + + /** * efi_signature_data - A format of signature * diff --git a/include/efi_loader.h b/include/efi_loader.h index 7fd65eeb8d..4719fa93f0 100644 --- a/include/efi_loader.h +++ b/include/efi_loader.h @@ -819,6 +819,8 @@ struct efi_signature_store *efi_sigstore_parse_sigdb(u16 *name); bool efi_secure_boot_enabled(void); +bool efi_capsule_auth_enabled(void); + bool efi_image_parse(void *efi, size_t len, struct efi_image_regions **regp, WIN_CERTIFICATE **auth, size_t *auth_len); @@ -847,6 +849,10 @@ efi_status_t EFIAPI efi_query_capsule_caps( u64 *maximum_capsule_size, u32 *reset_type); +efi_status_t efi_capsule_authenticate(const void *capsule, + efi_uintn_t capsule_size, + void **image, efi_uintn_t *image_size); + #define EFI_CAPSULE_DIR L"\\EFI\\UpdateCapsule\\" /* Hook at initialization */ diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig index e780491357..fdf245dea3 100644 --- a/lib/efi_loader/Kconfig +++ b/lib/efi_loader/Kconfig @@ -153,6 +153,23 @@ config EFI_CAPSULE_FIRMWARE_MANAGEMENT Select this option if you want to enable capsule-based firmware update using Firmware Management Protocol. +config EFI_CAPSULE_AUTHENTICATE + bool "Update Capsule authentication" + depends on EFI_CAPSULE_FIRMWARE + depends on EFI_CAPSULE_ON_DISK + depends on EFI_CAPSULE_FIRMWARE_MANAGEMENT + select SHA256 + select RSA + select RSA_VERIFY + select RSA_VERIFY_WITH_PKEY + select X509_CERTIFICATE_PARSER + select PKCS7_MESSAGE_PARSER + select PKCS7_VERIFY + default n + help + Select this option if you want to enable capsule + authentication + config EFI_CAPSULE_FIRMWARE_FIT bool "FMP driver for FIT image" depends on EFI_CAPSULE_FIRMWARE_MANAGEMENT diff --git a/lib/efi_loader/efi_capsule.c b/lib/efi_loader/efi_capsule.c index 4ef2546267..dad1b0fcf7 100644 --- a/lib/efi_loader/efi_capsule.c +++ b/lib/efi_loader/efi_capsule.c @@ -14,6 +14,10 @@ #include #include +#include +#include +#include + const efi_guid_t efi_guid_capsule_report = EFI_CAPSULE_REPORT_GUID; static const efi_guid_t efi_guid_firmware_management_capsule_id = EFI_FIRMWARE_MANAGEMENT_CAPSULE_ID_GUID; @@ -191,6 +195,124 @@ skip: return NULL; } +#if defined(CONFIG_EFI_CAPSULE_AUTHENTICATE) + +const efi_guid_t efi_guid_capsule_root_cert_guid = + EFI_FIRMWARE_MANAGEMENT_CAPSULE_ID_GUID; + +__weak int efi_get_public_key_data(void **pkey, efi_uintn_t *pkey_len) +{ + /* The platform is supposed to provide + * a method for getting the public key + * stored in the form of efi signature + * list + */ + return 0; +} + +efi_status_t efi_capsule_authenticate(const void *capsule, efi_uintn_t capsule_size, + void **image, efi_uintn_t *image_size) +{ + u8 *buf; + int ret; + void *fdt_pkey, *pkey; + efi_uintn_t pkey_len; + uint64_t monotonic_count; + struct efi_signature_store *truststore; + struct pkcs7_message *capsule_sig; + struct efi_image_regions *regs; + struct efi_firmware_image_authentication *auth_hdr; + efi_status_t status; + + status = EFI_SECURITY_VIOLATION; + capsule_sig = NULL; + truststore = NULL; + regs = NULL; + + /* Sanity checks */ + if (capsule == NULL || capsule_size == 0) + goto out; + + auth_hdr = (struct efi_firmware_image_authentication *)capsule; + if (capsule_size < sizeof(*auth_hdr)) + goto out; + + if (auth_hdr->auth_info.hdr.dwLength <= + offsetof(struct win_certificate_uefi_guid, cert_data)) + goto out; + + if (guidcmp(&auth_hdr->auth_info.cert_type, &efi_guid_cert_type_pkcs7)) + goto out; + + *image = (uint8_t *)capsule + sizeof(auth_hdr->monotonic_count) + + auth_hdr->auth_info.hdr.dwLength; + *image_size = capsule_size - auth_hdr->auth_info.hdr.dwLength - + sizeof(auth_hdr->monotonic_count); + memcpy(&monotonic_count, &auth_hdr->monotonic_count, + sizeof(monotonic_count)); + + /* data to be digested */ + regs = calloc(sizeof(*regs) + sizeof(struct image_region) * 2, 1); + if (!regs) + goto out; + + regs->max = 2; + efi_image_region_add(regs, (uint8_t *)*image, + (uint8_t *)*image + *image_size, 1); + + efi_image_region_add(regs, (uint8_t *)&monotonic_count, + (uint8_t *)&monotonic_count + sizeof(monotonic_count), + 1); + + capsule_sig = efi_parse_pkcs7_header(auth_hdr->auth_info.cert_data, + auth_hdr->auth_info.hdr.dwLength + - sizeof(auth_hdr->auth_info), + &buf); + if (IS_ERR(capsule_sig)) { + debug("Parsing variable's pkcs7 header failed\n"); + capsule_sig = NULL; + goto out; + } + + ret = efi_get_public_key_data(&fdt_pkey, &pkey_len); + if (ret < 0) + goto out; + + pkey = malloc(pkey_len); + if (!pkey) + goto out; + + memcpy(pkey, fdt_pkey, pkey_len); + truststore = efi_build_signature_store(pkey, pkey_len); + if (!truststore) + goto out; + + /* verify signature */ + if (efi_signature_verify(regs, capsule_sig, truststore, NULL)) { + debug("Verified\n"); + } else { + debug("Verifying variable's signature failed\n"); + goto out; + } + + status = EFI_SUCCESS; + +out: + efi_sigstore_free(truststore); + pkcs7_free_message(capsule_sig); + free(regs); + + return status; +} +#else +efi_status_t efi_capsule_authenticate(const void *capsule, efi_uintn_t capsule_size, + void **image, efi_uintn_t *image_size) +{ + return EFI_UNSUPPORTED; +} +#endif /* CONFIG_EFI_CAPSULE_AUTHENTICATE */ + + /** * efi_capsule_update_firmware - update firmware from capsule * @capsule_data: Capsule diff --git a/lib/efi_loader/efi_signature.c b/lib/efi_loader/efi_signature.c index 87525bdc80..c7ec275414 100644 --- a/lib/efi_loader/efi_signature.c +++ b/lib/efi_loader/efi_signature.c @@ -26,7 +26,7 @@ const efi_guid_t efi_guid_cert_x509 = EFI_CERT_X509_GUID; const efi_guid_t efi_guid_cert_x509_sha256 = EFI_CERT_X509_SHA256_GUID; const efi_guid_t efi_guid_cert_type_pkcs7 = EFI_CERT_TYPE_PKCS7_GUID; -#ifdef CONFIG_EFI_SECURE_BOOT +#if defined(CONFIG_EFI_SECURE_BOOT) || defined(CONFIG_EFI_CAPSULE_AUTHENTICATE) static u8 pkcs7_hdr[] = { /* SEQUENCE */ 0x30, 0x82, 0x05, 0xc7, @@ -846,4 +846,4 @@ struct efi_signature_store *efi_sigstore_parse_sigdb(u16 *name) return efi_build_signature_store(db, db_size); } -#endif /* CONFIG_EFI_SECURE_BOOT */ +#endif /* CONFIG_EFI_SECURE_BOOT || CONFIG_EFI_CAPSULE_AUTHENTICATE */ -- cgit v1.2.3