diff options
Diffstat (limited to 'lib')
-rw-r--r-- | lib/efi_loader/Kconfig | 1 | ||||
-rw-r--r-- | lib/efi_loader/efi_image_loader.c | 33 | ||||
-rw-r--r-- | lib/efi_loader/efi_signature.c | 413 | ||||
-rw-r--r-- | lib/efi_loader/efi_variable.c | 42 |
4 files changed, 208 insertions, 281 deletions
diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig index 6017ffe9a6..bad1a29ba8 100644 --- a/lib/efi_loader/Kconfig +++ b/lib/efi_loader/Kconfig @@ -205,6 +205,7 @@ config EFI_SECURE_BOOT select ASYMMETRIC_PUBLIC_KEY_SUBTYPE select X509_CERTIFICATE_PARSER select PKCS7_MESSAGE_PARSER + select PKCS7_VERIFY default n help Select this option to enable EFI secure boot support. diff --git a/lib/efi_loader/efi_image_loader.c b/lib/efi_loader/efi_image_loader.c index fef0bb870c..eea42cc204 100644 --- a/lib/efi_loader/efi_image_loader.c +++ b/lib/efi_loader/efi_image_loader.c @@ -546,6 +546,11 @@ static bool efi_image_authenticate(void *efi, size_t efi_size) goto err; } + if (efi_signature_lookup_digest(regs, dbx)) { + EFI_PRINT("Image's digest was found in \"dbx\"\n"); + goto err; + } + /* * go through WIN_CERTIFICATE list * NOTE: @@ -553,10 +558,9 @@ static bool efi_image_authenticate(void *efi, size_t efi_size) * in PE header, or as pkcs7 SignerInfo's in SignedData. * So the verification policy here is: * - Success if, at least, one of signatures is verified - * - unless - * any of signatures is rejected explicitly, or - * none of digest algorithms are supported + * - unless signature is rejected explicitly with its digest. */ + for (wincert = wincerts, wincerts_end = (u8 *)wincerts + wincerts_len; (u8 *)wincert < wincerts_end; wincert = (WIN_CERTIFICATE *) @@ -627,32 +631,29 @@ static bool efi_image_authenticate(void *efi, size_t efi_size) /* try black-list first */ if (efi_signature_verify_one(regs, msg, dbx)) { EFI_PRINT("Signature was rejected by \"dbx\"\n"); - goto err; + continue; } if (!efi_signature_check_signers(msg, dbx)) { EFI_PRINT("Signer(s) in \"dbx\"\n"); - goto err; - } - - if (efi_signature_lookup_digest(regs, dbx)) { - EFI_PRINT("Image's digest was found in \"dbx\"\n"); - goto err; + continue; } /* try white-list */ - if (efi_signature_verify_with_sigdb(regs, msg, db, dbx)) - continue; + if (efi_signature_verify(regs, msg, db, dbx)) { + ret = true; + break; + } debug("Signature was not verified by \"db\"\n"); - if (efi_signature_lookup_digest(regs, db)) - continue; + if (efi_signature_lookup_digest(regs, db)) { + ret = true; + break; + } debug("Image's digest was not found in \"db\" or \"dbx\"\n"); - goto err; } - ret = true; err: efi_sigstore_free(db); diff --git a/lib/efi_loader/efi_signature.c b/lib/efi_loader/efi_signature.c index fc0314e6d4..79dee27421 100644 --- a/lib/efi_loader/efi_signature.c +++ b/lib/efi_loader/efi_signature.c @@ -10,7 +10,9 @@ #include <image.h> #include <hexdump.h> #include <malloc.h> +#include <crypto/pkcs7.h> #include <crypto/pkcs7_parser.h> +#include <crypto/public_key.h> #include <linux/compat.h> #include <linux/oid_registry.h> #include <u-boot/rsa.h> @@ -61,143 +63,6 @@ static bool efi_hash_regions(struct image_region *regs, int count, } /** - * 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; - - regtmp.data = msg->data; - regtmp.size = msg->data_len; - - return efi_hash_regions(®tmp, 1, hash, size); -} - -/** - * 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; - - EFI_PRINT("%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 { - EFI_PRINT("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 */ - EFI_PRINT("%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)) { - EFI_PRINT("%s: RSA verify authentication attribute\n", - __func__); - /* - * NOTE: This path will be executed only for - * PE image authentication - */ - - /* check if hash matches digest first */ - EFI_PRINT("checking msg digest first, len:0x%x\n", - ps_info->msgdigest_len); - -#ifdef DEBUG - EFI_PRINT("hash in database:\n"); - print_hex_dump(" ", DUMP_PREFIX_OFFSET, 16, 1, - ps_info->msgdigest, ps_info->msgdigest_len, - false); -#endif - /* against contentInfo first */ - hash = NULL; - if ((msg->data && efi_hash_msg_content(msg, &hash, &size)) || - /* for signed image */ - efi_hash_regions(regs->reg, regs->num, &hash, &size)) { - /* for authenticated variable */ - if (ps_info->msgdigest_len != size || - memcmp(hash, ps_info->msgdigest, size)) { - EFI_PRINT("Digest doesn't match\n"); - free(hash); - goto out; - } - - free(hash); - } else { - EFI_PRINT("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 { - EFI_PRINT("%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: - EFI_PRINT("%s: Exit, verified: %d\n", __func__, verified); - return verified; -} - -/** * efi_signature_lookup_digest - search for an image's digest in sigdb * @regs: List of regions to be authenticated * @db: Signature database for trusted certificates @@ -260,61 +125,129 @@ out: } /** - * 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 + * efi_lookup_certificate - find a certificate within db + * @msg: Signature + * @db: Signature database * - * 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). + * Search signature database pointed to by @db and find a certificate + * pointed to by @cert. * - * Return: true if signature is verified, false if not + * Return: true if found, false otherwise. */ -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) +static bool efi_lookup_certificate(struct x509_certificate *cert, + struct efi_signature_store *db) { - struct x509_certificate *cert; + struct efi_signature_store *siglist; struct efi_sig_data *sig_data; - bool verified = false; + struct image_region reg[1]; + void *hash = NULL, *hash_tmp = NULL; + size_t size = 0; + bool found = false; - EFI_PRINT("%s: Enter, %p, %p, %p, %p\n", __func__, - regs, signed_info, siglist, valid_cert); + EFI_PRINT("%s: Enter, %p, %p\n", __func__, cert, db); - if (guidcmp(&siglist->sig_type, &efi_guid_cert_x509)) { - EFI_PRINT("Signature type is not supported: %pUl\n", - &siglist->sig_type); + if (!cert || !db || !db->sig_data_list) 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 */ + /* + * TODO: identify a certificate using sha256 digest + * Is there any better way? + */ + /* calculate hash of TBSCertificate */ + reg[0].data = cert->tbs; + reg[0].size = cert->tbs_size; + if (!efi_hash_regions(reg, 1, &hash, &size)) + goto out; - cert = x509_cert_parse(sig_data->data, sig_data->size); - if (IS_ERR(cert)) { - EFI_PRINT("Parsing x509 certificate failed\n"); - goto out; + EFI_PRINT("%s: searching for %s\n", __func__, cert->subject); + for (siglist = db; siglist; siglist = siglist->next) { + /* only with x509 certificate */ + if (guidcmp(&siglist->sig_type, &efi_guid_cert_x509)) + continue; + + for (sig_data = siglist->sig_data_list; sig_data; + sig_data = sig_data->next) { + struct x509_certificate *cert_tmp; + + cert_tmp = x509_cert_parse(sig_data->data, + sig_data->size); + if (IS_ERR_OR_NULL(cert_tmp)) + continue; + + EFI_PRINT("%s: against %s\n", __func__, + cert_tmp->subject); + reg[0].data = cert_tmp->tbs; + reg[0].size = cert_tmp->tbs_size; + if (!efi_hash_regions(reg, 1, &hash_tmp, NULL)) + goto out; + + x509_free_certificate(cert_tmp); + + if (!memcmp(hash, hash_tmp, size)) { + found = true; + goto out; + } } + } +out: + free(hash); + free(hash_tmp); - verified = efi_signature_verify(regs, msg, signed_info, cert); + EFI_PRINT("%s: Exit, found: %d\n", __func__, found); + return found; +} - if (verified) { - if (valid_cert) - *valid_cert = cert; - else - x509_free_certificate(cert); - break; +/** + * efi_verify_certificate - verify certificate's signature with database + * @signer: Certificate + * @db: Signature database + * @root: Certificate to verify @signer + * + * Determine if certificate pointed to by @signer may be verified + * by one of certificates in signature database pointed to by @db. + * + * Return: true if certificate is verified, false otherwise. + */ +static bool efi_verify_certificate(struct x509_certificate *signer, + struct efi_signature_store *db, + struct x509_certificate **root) +{ + struct efi_signature_store *siglist; + struct efi_sig_data *sig_data; + struct x509_certificate *cert; + bool verified = false; + int ret; + + EFI_PRINT("%s: Enter, %p, %p\n", __func__, signer, db); + + if (!signer || !db || !db->sig_data_list) + goto out; + + for (siglist = db; siglist; siglist = siglist->next) { + /* only with x509 certificate */ + if (guidcmp(&siglist->sig_type, &efi_guid_cert_x509)) + continue; + + for (sig_data = siglist->sig_data_list; sig_data; + sig_data = sig_data->next) { + cert = x509_cert_parse(sig_data->data, sig_data->size); + if (IS_ERR_OR_NULL(cert)) { + EFI_PRINT("Cannot parse x509 certificate\n"); + continue; + } + + ret = public_key_verify_signature(cert->pub, + signer->sig); + if (!ret) { + verified = true; + if (root) + *root = cert; + else + x509_free_certificate(cert); + goto out; + } + x509_free_certificate(cert); } - x509_free_certificate(cert); } out: @@ -335,7 +268,7 @@ out: * protocol at this time and any image will be unconditionally revoked * when this match occurs. * - * Return: true if check passed, false otherwise. + * Return: true if check passed (not found), false otherwise. */ static bool efi_signature_check_revocation(struct pkcs7_signed_info *sinfo, struct x509_certificate *cert, @@ -405,56 +338,8 @@ out: return !revoked; } -/** - * efi_signature_verify_one - verify signatures with database - * @regs: List of regions to be authenticated - * @msg: Signature - * @db: Signature database - * - * All the signature pointed to by @msg against image pointed to by @regs - * will be verified by signature database pointed to by @db. - * - * Return: true if verification for one of signatures passed, false - * otherwise - */ -bool efi_signature_verify_one(struct efi_image_regions *regs, - struct pkcs7_message *msg, - struct efi_signature_store *db) -{ - struct pkcs7_signed_info *sinfo; - struct efi_signature_store *siglist; - struct x509_certificate *cert; - bool verified = false; - - EFI_PRINT("%s: Enter, %p, %p, %p\n", __func__, regs, msg, db); - - if (!db) - goto out; - - if (!db->sig_data_list) - goto out; - - EFI_PRINT("%s: Verify signed image with db\n", __func__); - for (sinfo = msg->signed_infos; sinfo; sinfo = sinfo->next) { - EFI_PRINT("Signed Info: digest algo: %s, pkey algo: %s\n", - sinfo->sig->hash_algo, sinfo->sig->pkey_algo); - - for (siglist = db; siglist; siglist = siglist->next) - if (efi_signature_verify_with_list(regs, msg, sinfo, - siglist, &cert)) { - verified = true; - goto out; - } - EFI_PRINT("Valid certificate not in \"db\"\n"); - } - -out: - EFI_PRINT("%s: Exit, verified: %d\n", __func__, verified); - return verified; -} - -/** - * efi_signature_verify_with_sigdb - verify signatures with db and dbx +/* + * efi_signature_verify - verify signatures with db and dbx * @regs: List of regions to be authenticated * @msg: Signature * @db: Signature database for trusted certificates @@ -465,43 +350,71 @@ out: * * Return: true if verification for all signatures passed, false otherwise */ -bool efi_signature_verify_with_sigdb(struct efi_image_regions *regs, - struct pkcs7_message *msg, - struct efi_signature_store *db, - struct efi_signature_store *dbx) +bool efi_signature_verify(struct efi_image_regions *regs, + struct pkcs7_message *msg, + struct efi_signature_store *db, + struct efi_signature_store *dbx) { - struct pkcs7_signed_info *info; - struct efi_signature_store *siglist; - struct x509_certificate *cert; + struct pkcs7_signed_info *sinfo; + struct x509_certificate *signer, *root; bool verified = false; + int ret; EFI_PRINT("%s: Enter, %p, %p, %p, %p\n", __func__, regs, msg, db, dbx); if (!regs || !msg || !db || !db->sig_data_list) goto out; - for (info = msg->signed_infos; info; info = info->next) { + for (sinfo = msg->signed_infos; sinfo; sinfo = sinfo->next) { EFI_PRINT("Signed Info: digest algo: %s, pkey algo: %s\n", - info->sig->hash_algo, info->sig->pkey_algo); + sinfo->sig->hash_algo, sinfo->sig->pkey_algo); - for (siglist = db; siglist; siglist = siglist->next) { - if (efi_signature_verify_with_list(regs, msg, info, - siglist, &cert)) - break; - } - if (!siglist) { - EFI_PRINT("Valid certificate not in \"db\"\n"); + /* + * only for authenticated variable. + * + * If this function is called for image, + * hash calculation will be done in + * pkcs7_verify_one(). + */ + if (!msg->data && + !efi_hash_regions(regs->reg, regs->num, + (void **)&sinfo->sig->digest, NULL)) { + EFI_PRINT("Digesting an image failed\n"); goto out; } - if (!dbx || efi_signature_check_revocation(info, cert, dbx)) + EFI_PRINT("Verifying certificate chain\n"); + signer = NULL; + ret = pkcs7_verify_one(msg, sinfo, &signer); + if (ret == -ENOPKG) continue; - EFI_PRINT("Certificate in \"dbx\"\n"); - goto out; - } - verified = true; + if (ret < 0 || !signer) + goto out; + + if (sinfo->blacklisted) + goto out; + EFI_PRINT("Verifying last certificate in chain\n"); + if (signer->self_signed) { + if (efi_lookup_certificate(signer, db)) + if (efi_signature_check_revocation(sinfo, + signer, dbx)) + break; + } else if (efi_verify_certificate(signer, db, &root)) { + bool check; + + check = efi_signature_check_revocation(sinfo, root, + dbx); + x509_free_certificate(root); + if (check) + break; + } + + EFI_PRINT("Certificate chain didn't reach trusted CA\n"); + } + if (sinfo) + verified = true; out: EFI_PRINT("%s: Exit, verified: %d\n", __func__, verified); return verified; diff --git a/lib/efi_loader/efi_variable.c b/lib/efi_loader/efi_variable.c index e509d6dbf0..a10b9caa8b 100644 --- a/lib/efi_loader/efi_variable.c +++ b/lib/efi_loader/efi_variable.c @@ -37,16 +37,21 @@ static u8 pkcs7_hdr[] = { * efi_variable_parse_signature - parse a signature in variable * @buf: Pointer to variable's value * @buflen: Length of @buf + * @tmpbuf: Pointer to temporary buffer * * Parse a signature embedded in variable'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, particularly for variable's. + * 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 */ static struct pkcs7_message *efi_variable_parse_signature(const void *buf, - size_t buflen) + size_t buflen, + u8 **tmpbuf) { u8 *ebuf; size_t ebuflen, len; @@ -59,7 +64,9 @@ static struct pkcs7_message *efi_variable_parse_signature(const void *buf, if (buflen > sizeof(pkcs7_hdr) && !memcmp(&((u8 *)buf)[4], &pkcs7_hdr[4], 11)) { msg = pkcs7_parse_message(buf, buflen); - goto out; + if (IS_ERR(msg)) + return NULL; + return msg; } /* @@ -94,12 +101,12 @@ static struct pkcs7_message *efi_variable_parse_signature(const void *buf, msg = pkcs7_parse_message(ebuf, ebuflen); - free(ebuf); - -out: - if (IS_ERR(msg)) + if (IS_ERR(msg)) { + free(ebuf); return NULL; + } + *tmpbuf = ebuf; return msg; } @@ -136,6 +143,7 @@ static efi_status_t efi_variable_authenticate(u16 *variable, struct efi_time timestamp; struct rtc_time tm; u64 new_time; + u8 *ebuf; enum efi_auth_var_type var_type; efi_status_t ret; @@ -143,6 +151,7 @@ static efi_status_t efi_variable_authenticate(u16 *variable, truststore = NULL; truststore2 = NULL; regs = NULL; + ebuf = NULL; ret = EFI_SECURITY_VIOLATION; if (*data_size < sizeof(struct efi_variable_authentication_2)) @@ -204,9 +213,12 @@ static efi_status_t efi_variable_authenticate(u16 *variable, /* variable's signature list */ if (auth->auth_info.hdr.dwLength < sizeof(auth->auth_info)) goto err; + + /* ebuf should be kept valid during the authentication */ var_sig = efi_variable_parse_signature(auth->auth_info.cert_data, auth->auth_info.hdr.dwLength - - sizeof(auth->auth_info)); + - sizeof(auth->auth_info), + &ebuf); if (!var_sig) { EFI_PRINT("Parsing variable's signature failed\n"); goto err; @@ -241,12 +253,11 @@ static efi_status_t efi_variable_authenticate(u16 *variable, } /* verify signature */ - if (efi_signature_verify_with_sigdb(regs, var_sig, truststore, NULL)) { + if (efi_signature_verify(regs, var_sig, truststore, NULL)) { EFI_PRINT("Verified\n"); } else { if (truststore2 && - efi_signature_verify_with_sigdb(regs, var_sig, - truststore2, NULL)) { + efi_signature_verify(regs, var_sig, truststore2, NULL)) { EFI_PRINT("Verified\n"); } else { EFI_PRINT("Verifying variable's signature failed\n"); @@ -262,6 +273,7 @@ err: efi_sigstore_free(truststore); efi_sigstore_free(truststore2); pkcs7_free_message(var_sig); + free(ebuf); free(regs); return ret; @@ -496,10 +508,6 @@ efi_status_t efi_init_variables(void) if (ret != EFI_SUCCESS) return ret; - ret = efi_init_secure_state(); - if (ret != EFI_SUCCESS) - return ret; - if (IS_ENABLED(CONFIG_EFI_VARIABLES_PRESEED)) { ret = efi_var_restore((struct efi_var_file *) __efi_var_file_begin); @@ -507,5 +515,9 @@ efi_status_t efi_init_variables(void) log_err("Invalid EFI variable seed\n"); } - return efi_var_from_file(); + ret = efi_var_from_file(); + if (ret != EFI_SUCCESS) + return ret; + + return efi_init_secure_state(); } |