diff options
Diffstat (limited to 'lib/efi_loader/efi_signature.c')
| -rw-r--r-- | lib/efi_loader/efi_signature.c | 804 |
1 files changed, 804 insertions, 0 deletions
diff --git a/lib/efi_loader/efi_signature.c b/lib/efi_loader/efi_signature.c new file mode 100644 index 0000000000..658e3547da --- /dev/null +++ b/lib/efi_loader/efi_signature.c @@ -0,0 +1,804 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Copyright (c) 2018 Patrick Wildt <patrick@blueri.se> + * Copyright (c) 2019 Linaro Limited, Author: AKASHI Takahiro + */ + +#include <common.h> +#include <charset.h> +#include <efi_loader.h> +#include <image.h> +#include <hexdump.h> +#include <malloc.h> +#include <linux/compat.h> +#include <linux/oid_registry.h> +#include <u-boot/rsa.h> +#include <u-boot/sha256.h> +#include "../lib/crypto/pkcs7_parser.h" + +const efi_guid_t efi_guid_image_security_database = + EFI_IMAGE_SECURITY_DATABASE_GUID; +const efi_guid_t efi_guid_sha256 = EFI_CERT_SHA256_GUID; +const efi_guid_t efi_guid_cert_rsa2048 = EFI_CERT_RSA2048_GUID; +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; + +#ifdef CONFIG_EFI_SECURE_BOOT + +/** + * efi_hash_regions - calculate a hash value + * @regs: List of regions + * @hash: Pointer to a pointer to buffer holding a hash value + * @size: Size of buffer to be returned + * + * Calculate a sha256 value of @regs and return a value in @hash. + * + * Return: true on success, false on error + */ +static bool efi_hash_regions(struct efi_image_regions *regs, void **hash, + size_t *size) +{ + *size = 0; + *hash = calloc(1, SHA256_SUM_LEN); + if (!*hash) { + debug("Out of memory\n"); + return false; + } + *size = SHA256_SUM_LEN; + + hash_calculate("sha256", regs->reg, regs->num, *hash); +#ifdef DEBUG + debug("hash calculated:\n"); + print_hex_dump(" ", DUMP_PREFIX_OFFSET, 16, 1, + *hash, SHA256_SUM_LEN, false); +#endif + + return true; +} + +/** + * efi_hash_msg_content - calculate a hash value of contentInfo + * @msg: Signature + * @hash: Pointer to a pointer to buffer holding a hash value + * @size: Size of buffer to be returned + * + * Calculate a sha256 value of contentInfo in @msg and return a value in @hash. + * + * Return: true on success, false on error + */ +static bool efi_hash_msg_content(struct pkcs7_message *msg, void **hash, + size_t *size) +{ + struct image_region regtmp; + + *size = 0; + *hash = calloc(1, SHA256_SUM_LEN); + if (!*hash) { + debug("Out of memory\n"); + free(msg); + return false; + } + *size = SHA256_SUM_LEN; + + regtmp.data = msg->data; + regtmp.size = msg->data_len; + + hash_calculate("sha256", ®tmp, 1, *hash); +#ifdef DEBUG + debug("hash calculated based on contentInfo:\n"); + print_hex_dump(" ", DUMP_PREFIX_OFFSET, 16, 1, + *hash, SHA256_SUM_LEN, false); +#endif + + return true; +} + +/** + * efi_signature_verify - verify a signature with a certificate + * @regs: List of regions to be authenticated + * @signed_info: Pointer to PKCS7's signed_info + * @cert: x509 certificate + * + * Signature pointed to by @signed_info against image pointed to by @regs + * is verified by a certificate pointed to by @cert. + * @signed_info holds a signature, including a message digest which is to be + * compared with a hash value calculated from @regs. + * + * Return: true if signature is verified, false if not + */ +static bool efi_signature_verify(struct efi_image_regions *regs, + struct pkcs7_message *msg, + struct pkcs7_signed_info *ps_info, + struct x509_certificate *cert) +{ + struct image_sign_info info; + struct image_region regtmp[2]; + void *hash; + size_t size; + char c; + bool verified; + + debug("%s: Enter, %p, %p, %p(issuer: %s, subject: %s)\n", __func__, + regs, ps_info, cert, cert->issuer, cert->subject); + + verified = false; + + memset(&info, '\0', sizeof(info)); + info.padding = image_get_padding_algo("pkcs-1.5"); + /* + * Note: image_get_[checksum|crypto]_algo takes an string + * argument like "<checksum>,<crypto>" + * TODO: support other hash algorithms + */ + if (!strcmp(ps_info->sig->hash_algo, "sha1")) { + info.checksum = image_get_checksum_algo("sha1,rsa2048"); + info.name = "sha1,rsa2048"; + } else if (!strcmp(ps_info->sig->hash_algo, "sha256")) { + info.checksum = image_get_checksum_algo("sha256,rsa2048"); + info.name = "sha256,rsa2048"; + } else { + debug("unknown msg digest algo: %s\n", ps_info->sig->hash_algo); + goto out; + } + info.crypto = image_get_crypto_algo(info.name); + + info.key = cert->pub->key; + info.keylen = cert->pub->keylen; + + /* verify signature */ + debug("%s: crypto: %s, signature len:%x\n", __func__, + info.name, ps_info->sig->s_size); + if (ps_info->aa_set & (1UL << sinfo_has_message_digest)) { + debug("%s: RSA verify authentication attribute\n", __func__); + /* + * NOTE: This path will be executed only for + * PE image authentication + */ + + /* check if hash matches digest first */ + debug("checking msg digest first, len:0x%x\n", + ps_info->msgdigest_len); + +#ifdef DEBUG + debug("hash in database:\n"); + print_hex_dump(" ", DUMP_PREFIX_OFFSET, 16, 1, + ps_info->msgdigest, ps_info->msgdigest_len, + false); +#endif + /* against contentInfo first */ + if ((msg->data && efi_hash_msg_content(msg, &hash, &size)) || + /* for signed image */ + efi_hash_regions(regs, &hash, &size)) { + /* for authenticated variable */ + if (ps_info->msgdigest_len != size || + memcmp(hash, ps_info->msgdigest, size)) { + debug("Digest doesn't match\n"); + free(hash); + goto out; + } + + free(hash); + } else { + debug("Digesting image failed\n"); + goto out; + } + + /* against digest */ + c = 0x31; + regtmp[0].data = &c; + regtmp[0].size = 1; + regtmp[1].data = ps_info->authattrs; + regtmp[1].size = ps_info->authattrs_len; + + if (!rsa_verify(&info, regtmp, 2, + ps_info->sig->s, ps_info->sig->s_size)) + verified = true; + } else { + debug("%s: RSA verify content data\n", __func__); + /* against all data */ + if (!rsa_verify(&info, regs->reg, regs->num, + ps_info->sig->s, ps_info->sig->s_size)) + verified = true; + } + +out: + debug("%s: Exit, verified: %d\n", __func__, verified); + return verified; +} + +/** + * efi_signature_verify_with_list - verify a signature with signature list + * @regs: List of regions to be authenticated + * @msg: Signature + * @signed_info: Pointer to PKCS7's signed_info + * @siglist: Signature list for certificates + * @valid_cert: x509 certificate that verifies this signature + * + * Signature pointed to by @signed_info against image pointed to by @regs + * is verified by signature list pointed to by @siglist. + * Signature database is a simple concatenation of one or more + * signature list(s). + * + * Return: true if signature is verified, false if not + */ +static +bool efi_signature_verify_with_list(struct efi_image_regions *regs, + struct pkcs7_message *msg, + struct pkcs7_signed_info *signed_info, + struct efi_signature_store *siglist, + struct x509_certificate **valid_cert) +{ + struct x509_certificate *cert; + struct efi_sig_data *sig_data; + bool verified = false; + + debug("%s: Enter, %p, %p, %p, %p\n", __func__, + regs, signed_info, siglist, valid_cert); + + if (!signed_info) { + void *hash; + size_t size; + + debug("%s: unsigned image\n", __func__); + /* + * verify based on calculated hash value + * TODO: support other hash algorithms + */ + if (guidcmp(&siglist->sig_type, &efi_guid_sha256)) { + debug("Digest algorithm is not supported: %pUl\n", + &siglist->sig_type); + goto out; + } + + if (!efi_hash_regions(regs, &hash, &size)) { + debug("Digesting unsigned image failed\n"); + goto out; + } + + /* go through the list */ + for (sig_data = siglist->sig_data_list; sig_data; + sig_data = sig_data->next) { +#ifdef DEBUG + debug("Msg digest in database:\n"); + print_hex_dump(" ", DUMP_PREFIX_OFFSET, 16, 1, + sig_data->data, sig_data->size, false); +#endif + if ((sig_data->size == size) && + !memcmp(sig_data->data, hash, size)) { + verified = true; + free(hash); + goto out; + } + } + free(hash); + goto out; + } + + debug("%s: signed image\n", __func__); + if (guidcmp(&siglist->sig_type, &efi_guid_cert_x509)) { + debug("Signature type is not supported: %pUl\n", + &siglist->sig_type); + goto out; + } + + /* go through the list */ + for (sig_data = siglist->sig_data_list; sig_data; + sig_data = sig_data->next) { + /* TODO: support owner check based on policy */ + + cert = x509_cert_parse(sig_data->data, sig_data->size); + if (IS_ERR(cert)) { + debug("Parsing x509 certificate failed\n"); + goto out; + } + + verified = efi_signature_verify(regs, msg, signed_info, cert); + + if (verified) { + if (valid_cert) + *valid_cert = cert; + else + x509_free_certificate(cert); + break; + } + x509_free_certificate(cert); + } + +out: + debug("%s: Exit, verified: %d\n", __func__, verified); + return verified; +} + +/** + * efi_signature_verify_with_sigdb - verify a signature with db + * @regs: List of regions to be authenticated + * @msg: Signature + * @db: Signature database for trusted certificates + * @cert: x509 certificate that verifies this signature + * + * Signature pointed to by @msg against image pointed to by @regs + * is verified by signature database pointed to by @db. + * + * Return: true if signature is verified, false if not + */ +bool efi_signature_verify_with_sigdb(struct efi_image_regions *regs, + struct pkcs7_message *msg, + struct efi_signature_store *db, + struct x509_certificate **cert) +{ + struct pkcs7_signed_info *info; + struct efi_signature_store *siglist; + bool verified = false; + + debug("%s: Enter, %p, %p, %p, %p\n", __func__, regs, msg, db, cert); + + if (!db) + goto out; + + if (!db->sig_data_list) + goto out; + + /* for unsigned image */ + if (!msg) { + debug("%s: Verify unsigned image with db\n", __func__); + for (siglist = db; siglist; siglist = siglist->next) + if (efi_signature_verify_with_list(regs, NULL, NULL, + siglist, cert)) { + verified = true; + goto out; + } + + goto out; + } + + /* for signed image or variable */ + debug("%s: Verify signed image with db\n", __func__); + for (info = msg->signed_infos; info; info = info->next) { + debug("Signed Info: digest algo: %s, pkey algo: %s\n", + info->sig->hash_algo, info->sig->pkey_algo); + + for (siglist = db; siglist; siglist = siglist->next) { + if (efi_signature_verify_with_list(regs, msg, info, + siglist, cert)) { + verified = true; + goto out; + } + } + } + +out: + debug("%s: Exit, verified: %d\n", __func__, verified); + return verified; +} + +/** + * efi_search_siglist - search signature list for a certificate + * @cert: x509 certificate + * @siglist: Signature list + * @revoc_time: Pointer to buffer for revocation time + * + * Search signature list pointed to by @siglist and find a certificate + * pointed to by @cert. + * If found, revocation time that is specified in signature database is + * returned in @revoc_time. + * + * Return: true if certificate is found, false if not + */ +static bool efi_search_siglist(struct x509_certificate *cert, + struct efi_signature_store *siglist, + time64_t *revoc_time) +{ + struct image_region reg[1]; + void *hash = NULL, *msg = NULL; + struct efi_sig_data *sig_data; + bool found = false; + + /* can be null */ + if (!siglist->sig_data_list) + return false; + + if (guidcmp(&siglist->sig_type, &efi_guid_cert_x509_sha256)) { + /* TODO: other hash algos */ + debug("Certificate's digest type is not supported: %pUl\n", + &siglist->sig_type); + goto out; + } + + /* calculate hash of TBSCertificate */ + msg = calloc(1, SHA256_SUM_LEN); + if (!msg) { + debug("Out of memory\n"); + goto out; + } + + hash = calloc(1, SHA256_SUM_LEN); + if (!hash) { + debug("Out of memory\n"); + goto out; + } + + reg[0].data = cert->tbs; + reg[0].size = cert->tbs_size; + hash_calculate("sha256", reg, 1, msg); + + /* go through signature list */ + for (sig_data = siglist->sig_data_list; sig_data; + sig_data = sig_data->next) { + /* + * struct efi_cert_x509_sha256 { + * u8 tbs_hash[256/8]; + * time64_t revocation_time; + * }; + */ + if ((sig_data->size == SHA256_SUM_LEN) && + !memcmp(sig_data->data, hash, SHA256_SUM_LEN)) { + memcpy(revoc_time, sig_data->data + SHA256_SUM_LEN, + sizeof(*revoc_time)); + found = true; + goto out; + } + } + +out: + free(hash); + free(msg); + + return found; +} + +/** + * efi_signature_verify_cert - verify a certificate with dbx + * @cert: x509 certificate + * @dbx: Signature database + * + * Search signature database pointed to by @dbx and find a certificate + * pointed to by @cert. + * This function is expected to be used against "dbx". + * + * Return: true if a certificate is not rejected, false otherwise. + */ +bool efi_signature_verify_cert(struct x509_certificate *cert, + struct efi_signature_store *dbx) +{ + struct efi_signature_store *siglist; + time64_t revoc_time; + bool found = false; + + debug("%s: Enter, %p, %p\n", __func__, dbx, cert); + + if (!cert) + return false; + + for (siglist = dbx; siglist; siglist = siglist->next) { + if (efi_search_siglist(cert, siglist, &revoc_time)) { + /* TODO */ + /* compare signing time with revocation time */ + + found = true; + break; + } + } + + debug("%s: Exit, verified: %d\n", __func__, !found); + return !found; +} + +/** + * efi_signature_verify_signers - verify signers' certificates with dbx + * @msg: Signature + * @dbx: Signature database + * + * Determine if any of signers' certificates in @msg may be verified + * by any of certificates in signature database pointed to by @dbx. + * This function is expected to be used against "dbx". + * + * Return: true if none of certificates is rejected, false otherwise. + */ +bool efi_signature_verify_signers(struct pkcs7_message *msg, + struct efi_signature_store *dbx) +{ + struct pkcs7_signed_info *info; + bool found = false; + + debug("%s: Enter, %p, %p\n", __func__, msg, dbx); + + if (!msg) + goto out; + + for (info = msg->signed_infos; info; info = info->next) { + if (info->signer && + !efi_signature_verify_cert(info->signer, dbx)) { + found = true; + goto out; + } + } +out: + debug("%s: Exit, verified: %d\n", __func__, !found); + return !found; +} + +/** + * efi_image_region_add - add an entry of region + * @regs: Pointer to array of regions + * @start: Start address of region + * @end: End address of region + * @nocheck: flag against overlapped regions + * + * Take one entry of region [@start, @end] and append it to the list + * pointed to by @regs. If @nocheck is false, overlapping among entries + * will be checked first. + * + * Return: 0 on success, status code (negative) on error + */ +efi_status_t efi_image_region_add(struct efi_image_regions *regs, + const void *start, const void *end, + int nocheck) +{ + struct image_region *reg; + int i, j; + + if (regs->num >= regs->max) { + debug("%s: no more room for regions\n", __func__); + return EFI_OUT_OF_RESOURCES; + } + + if (end < start) + return EFI_INVALID_PARAMETER; + + for (i = 0; i < regs->num; i++) { + reg = ®s->reg[i]; + if (nocheck) + continue; + + if (start > reg->data + reg->size) + continue; + + if ((start >= reg->data && start < reg->data + reg->size) || + (end > reg->data && end < reg->data + reg->size)) { + debug("%s: new region already part of another\n", + __func__); + return EFI_INVALID_PARAMETER; + } + + if (start < reg->data && end < reg->data + reg->size) { + for (j = regs->num - 1; j >= i; j--) + memcpy(®s->reg[j], ®s->reg[j + 1], + sizeof(*reg)); + break; + } + } + + reg = ®s->reg[i]; + reg->data = start; + reg->size = end - start; + regs->num++; + + return EFI_SUCCESS; +} + +/** + * efi_sigstore_free - free signature store + * @sigstore: Pointer to signature store structure + * + * Feee all the memories held in signature store and itself, + * which were allocated by efi_sigstore_parse_sigdb(). + */ +void efi_sigstore_free(struct efi_signature_store *sigstore) +{ + struct efi_signature_store *sigstore_next; + struct efi_sig_data *sig_data, *sig_data_next; + + while (sigstore) { + sigstore_next = sigstore->next; + + sig_data = sigstore->sig_data_list; + while (sig_data) { + sig_data_next = sig_data->next; + free(sig_data->data); + free(sig_data); + sig_data = sig_data_next; + } + + free(sigstore); + sigstore = sigstore_next; + } +} + +/** + * efi_sigstore_parse_siglist - parse a signature list + * @name: Pointer to signature list + * + * Parse signature list and instantiate a signature store structure. + * Signature database is a simple concatenation of one or more + * signature list(s). + * + * Return: Pointer to signature store on success, NULL on error + */ +static struct efi_signature_store * +efi_sigstore_parse_siglist(struct efi_signature_list *esl) +{ + struct efi_signature_store *siglist = NULL; + struct efi_sig_data *sig_data, *sig_data_next; + struct efi_signature_data *esd; + size_t left; + + /* + * UEFI specification defines certificate types: + * for non-signed images, + * EFI_CERT_SHA256_GUID + * EFI_CERT_RSA2048_GUID + * EFI_CERT_RSA2048_SHA256_GUID + * EFI_CERT_SHA1_GUID + * EFI_CERT_RSA2048_SHA_GUID + * EFI_CERT_SHA224_GUID + * EFI_CERT_SHA384_GUID + * EFI_CERT_SHA512_GUID + * + * for signed images, + * EFI_CERT_X509_GUID + * NOTE: Each certificate will normally be in a separate + * EFI_SIGNATURE_LIST as the size may vary depending on + * its algo's. + * + * for timestamp revocation of certificate, + * EFI_CERT_X509_SHA512_GUID + * EFI_CERT_X509_SHA256_GUID + * EFI_CERT_X509_SHA384_GUID + */ + + if (esl->signature_list_size + <= (sizeof(*esl) + esl->signature_header_size)) { + debug("Siglist in wrong format\n"); + return NULL; + } + + /* Create a head */ + siglist = calloc(sizeof(*siglist), 1); + if (!siglist) { + debug("Out of memory\n"); + goto err; + } + memcpy(&siglist->sig_type, &esl->signature_type, sizeof(efi_guid_t)); + + /* Go through the list */ + sig_data_next = NULL; + left = esl->signature_list_size + - (sizeof(*esl) + esl->signature_header_size); + esd = (struct efi_signature_data *) + ((u8 *)esl + sizeof(*esl) + esl->signature_header_size); + + while ((left > 0) && left >= esl->signature_size) { + /* Signature must exist if there is remaining data. */ + if (left < esl->signature_size) { + debug("Certificate is too small\n"); + goto err; + } + + sig_data = calloc(esl->signature_size + - sizeof(esd->signature_owner), 1); + if (!sig_data) { + debug("Out of memory\n"); + goto err; + } + + /* Append signature data */ + memcpy(&sig_data->owner, &esd->signature_owner, + sizeof(efi_guid_t)); + sig_data->size = esl->signature_size + - sizeof(esd->signature_owner); + sig_data->data = malloc(sig_data->size); + if (!sig_data->data) { + debug("Out of memory\n"); + goto err; + } + memcpy(sig_data->data, esd->signature_data, sig_data->size); + + sig_data->next = sig_data_next; + sig_data_next = sig_data; + + /* Next */ + esd = (struct efi_signature_data *) + ((u8 *)esd + esl->signature_size); + left -= esl->signature_size; + } + siglist->sig_data_list = sig_data_next; + + return siglist; + +err: + efi_sigstore_free(siglist); + + return NULL; +} + +/** + * efi_sigstore_parse_sigdb - parse a signature database variable + * @name: Variable's name + * + * Read in a value of signature database variable pointed to by + * @name, parse it and instantiate a signature store structure. + * + * Return: Pointer to signature store on success, NULL on error + */ +struct efi_signature_store *efi_sigstore_parse_sigdb(u16 *name) +{ + struct efi_signature_store *sigstore = NULL, *siglist; + struct efi_signature_list *esl; + const efi_guid_t *vendor; + void *db; + efi_uintn_t db_size; + efi_status_t ret; + + if (!u16_strcmp(name, L"PK") || !u16_strcmp(name, L"KEK")) { + vendor = &efi_global_variable_guid; + } else if (!u16_strcmp(name, L"db") || !u16_strcmp(name, L"dbx")) { + vendor = &efi_guid_image_security_database; + } else { + debug("unknown signature database, %ls\n", name); + return NULL; + } + + /* retrieve variable data */ + db_size = 0; + ret = EFI_CALL(efi_get_variable(name, vendor, NULL, &db_size, NULL)); + if (ret == EFI_NOT_FOUND) { + debug("variable, %ls, not found\n", name); + sigstore = calloc(sizeof(*sigstore), 1); + return sigstore; + } else if (ret != EFI_BUFFER_TOO_SMALL) { + debug("Getting variable, %ls, failed\n", name); + return NULL; + } + + db = malloc(db_size); + if (!db) { + debug("Out of memory\n"); + return NULL; + } + + ret = EFI_CALL(efi_get_variable(name, vendor, NULL, &db_size, db)); + if (ret != EFI_SUCCESS) { + debug("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)) { + debug("variable, %ls, in wrong format\n", name); + goto err; + } + + if (db_size < esl->signature_list_size) { + debug("variable, %ls, in wrong format\n", name); + goto err; + } + + /* Parse a single siglist. */ + siglist = efi_sigstore_parse_siglist(esl); + if (!siglist) { + debug("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 sigstore; + +err: + efi_sigstore_free(sigstore); + free(db); + + return NULL; +} +#endif /* CONFIG_EFI_SECURE_BOOT */ |