From 1a44b7059c183a227f2fc4519df24da09d403cba Mon Sep 17 00:00:00 2001 From: AKASHI Takahiro Date: Wed, 8 Jul 2020 14:01:52 +0900 Subject: efi_loader: image_loader: add a check against certificate type of authenticode UEFI specification requires that we shall support three type of certificates of authenticode in PE image: WIN_CERT_TYPE_EFI_GUID with the guid, EFI_CERT_TYPE_PCKS7_GUID WIN_CERT_TYPE_PKCS_SIGNED_DATA WIN_CERT_TYPE_EFI_PKCS1_15 As EDK2 does, we will support the first two that are pkcs7 SignedData. Signed-off-by: AKASHI Takahiro --- lib/efi_loader/efi_image_loader.c | 56 ++++++++++++++++++++++++++++++--------- 1 file changed, 44 insertions(+), 12 deletions(-) (limited to 'lib/efi_loader/efi_image_loader.c') diff --git a/lib/efi_loader/efi_image_loader.c b/lib/efi_loader/efi_image_loader.c index 06a2ebdb908..9b01e1ec90b 100644 --- a/lib/efi_loader/efi_image_loader.c +++ b/lib/efi_loader/efi_image_loader.c @@ -483,7 +483,8 @@ static bool efi_image_authenticate(void *efi, size_t efi_size) struct efi_signature_store *db = NULL, *dbx = NULL; struct x509_certificate *cert = NULL; void *new_efi = NULL; - size_t new_efi_size; + u8 *auth, *wincerts_end; + size_t new_efi_size, auth_size; bool ret = false; if (!efi_secure_boot_enabled()) @@ -532,21 +533,52 @@ static bool efi_image_authenticate(void *efi, size_t efi_size) } /* go through WIN_CERTIFICATE list */ - for (wincert = wincerts; - (void *)wincert < (void *)wincerts + wincerts_len; - wincert = (void *)wincert + ALIGN(wincert->dwLength, 8)) { - if (wincert->dwLength < sizeof(*wincert)) { - EFI_PRINT("%s: dwLength too small: %u < %zu\n", - __func__, wincert->dwLength, - sizeof(*wincert)); - goto err; + for (wincert = wincerts, wincerts_end = (u8 *)wincerts + wincerts_len; + (u8 *)wincert < wincerts_end; + wincert = (WIN_CERTIFICATE *) + ((u8 *)wincert + ALIGN(wincert->dwLength, 8))) { + if ((u8 *)wincert + sizeof(*wincert) >= wincerts_end) + break; + + if (wincert->dwLength <= sizeof(*wincert)) { + EFI_PRINT("dwLength too small: %u < %zu\n", + wincert->dwLength, sizeof(*wincert)); + continue; + } + + EFI_PRINT("WIN_CERTIFICATE_TYPE: 0x%x\n", + wincert->wCertificateType); + + auth = (u8 *)wincert + sizeof(*wincert); + auth_size = wincert->dwLength - sizeof(*wincert); + if (wincert->wCertificateType == WIN_CERT_TYPE_EFI_GUID) { + if (auth + sizeof(efi_guid_t) >= wincerts_end) + break; + + if (auth_size <= sizeof(efi_guid_t)) { + EFI_PRINT("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: %pUl\n", + auth); + continue; + } + + auth += sizeof(efi_guid_t); + auth_size -= sizeof(efi_guid_t); + } else if (wincert->wCertificateType + != WIN_CERT_TYPE_PKCS_SIGNED_DATA) { + EFI_PRINT("Certificate type not supported\n"); + continue; } - msg = pkcs7_parse_message((void *)wincert + sizeof(*wincert), - wincert->dwLength - sizeof(*wincert)); + + msg = pkcs7_parse_message(auth, auth_size); if (IS_ERR(msg)) { EFI_PRINT("Parsing image's signature failed\n"); msg = NULL; - goto err; + continue; } /* try black-list first */ -- cgit v1.2.3 From eb537fd7eb05665a088766128eebd45b585679d3 Mon Sep 17 00:00:00 2001 From: AKASHI Takahiro Date: Wed, 8 Jul 2020 14:01:53 +0900 Subject: efi_loader: image_loader: retrieve authenticode only if it exists Since the certificate table, which is indexed by IMAGE_DIRECTORY_ENTRY_SECURITY and contains authenticode in PE image, doesn't always exist, we should make sure that we will retrieve its pointer only if it exists. Signed-off-by: AKASHI Takahiro --- lib/efi_loader/efi_image_loader.c | 29 +++++++++++++++++++++-------- 1 file changed, 21 insertions(+), 8 deletions(-) (limited to 'lib/efi_loader/efi_image_loader.c') diff --git a/lib/efi_loader/efi_image_loader.c b/lib/efi_loader/efi_image_loader.c index 9b01e1ec90b..de230409e33 100644 --- a/lib/efi_loader/efi_image_loader.c +++ b/lib/efi_loader/efi_image_loader.c @@ -267,6 +267,8 @@ bool efi_image_parse(void *efi, size_t len, struct efi_image_regions **regp, dos = (void *)efi; nt = (void *)(efi + dos->e_lfanew); + authoff = 0; + authsz = 0; /* * Count maximum number of regions to be digested. @@ -305,25 +307,36 @@ bool efi_image_parse(void *efi, size_t len, struct efi_image_regions **regp, efi_image_region_add(regs, &opt->DataDirectory[ctidx] + 1, efi + opt->SizeOfHeaders, 0); + + authoff = opt->DataDirectory[ctidx].VirtualAddress; + authsz = opt->DataDirectory[ctidx].Size; } bytes_hashed = opt->SizeOfHeaders; align = opt->FileAlignment; - authoff = opt->DataDirectory[ctidx].VirtualAddress; - authsz = opt->DataDirectory[ctidx].Size; } else if (nt->OptionalHeader.Magic == IMAGE_NT_OPTIONAL_HDR32_MAGIC) { IMAGE_OPTIONAL_HEADER32 *opt = &nt->OptionalHeader; + /* Skip CheckSum */ efi_image_region_add(regs, efi, &opt->CheckSum, 0); - efi_image_region_add(regs, &opt->Subsystem, - &opt->DataDirectory[ctidx], 0); - efi_image_region_add(regs, &opt->DataDirectory[ctidx] + 1, - efi + opt->SizeOfHeaders, 0); + if (nt->OptionalHeader.NumberOfRvaAndSizes <= ctidx) { + efi_image_region_add(regs, + &opt->Subsystem, + efi + opt->SizeOfHeaders, 0); + } else { + /* Skip Certificates Table */ + efi_image_region_add(regs, &opt->Subsystem, + &opt->DataDirectory[ctidx], 0); + efi_image_region_add(regs, + &opt->DataDirectory[ctidx] + 1, + efi + opt->SizeOfHeaders, 0); + + authoff = opt->DataDirectory[ctidx].VirtualAddress; + authsz = opt->DataDirectory[ctidx].Size; + } bytes_hashed = opt->SizeOfHeaders; align = opt->FileAlignment; - authoff = opt->DataDirectory[ctidx].VirtualAddress; - authsz = opt->DataDirectory[ctidx].Size; } else { EFI_PRINT("%s: Invalid optional header magic %x\n", __func__, nt->OptionalHeader.Magic); -- cgit v1.2.3 From 11bafb259648dea054e07dc5c8003eb8c736f36c Mon Sep 17 00:00:00 2001 From: AKASHI Takahiro Date: Wed, 8 Jul 2020 14:01:56 +0900 Subject: efi_loader: image_loader: verification for all signatures should pass A signed image may have multiple signatures in - each WIN_CERTIFICATE in authenticode, and/or - each SignerInfo in pkcs7 SignedData (of WIN_CERTIFICATE) In the initial implementation of efi_image_authenticate(), the criteria of verification check for multiple signatures case is a bit ambiguous and it may cause inconsistent result. With this patch, we will make sure that verification check in efi_image_authenticate() should pass against all the signatures. The only exception would be - the case where a digest algorithm used in signature is not supported by U-Boot, or - the case where parsing some portion of authenticode has failed In those cases, we don't know how the signature be handled and should just ignore them. Please note that, due to this change, efi_signature_verify_with_sigdb()'s function prototype will be modified, taking "dbx" as well as "db" instead of outputing a "certificate." If "dbx" is null, the behavior would be the exact same as before. The function's name will be changed to efi_signature_verify() once current efi_signature_verify() has gone due to further improvement in intermediate certificates support. Signed-off-by: AKASHI Takahiro --- lib/efi_loader/efi_image_loader.c | 43 ++++++++++++++++++++------------------- 1 file changed, 22 insertions(+), 21 deletions(-) (limited to 'lib/efi_loader/efi_image_loader.c') diff --git a/lib/efi_loader/efi_image_loader.c b/lib/efi_loader/efi_image_loader.c index de230409e33..058359fc258 100644 --- a/lib/efi_loader/efi_image_loader.c +++ b/lib/efi_loader/efi_image_loader.c @@ -448,13 +448,13 @@ static bool efi_image_unsigned_authenticate(struct efi_image_regions *regs) } /* try black-list first */ - if (efi_signature_verify_with_sigdb(regs, NULL, dbx, NULL)) { + if (efi_signature_verify_one(regs, NULL, dbx)) { EFI_PRINT("Image is not signed and rejected by \"dbx\"\n"); goto out; } /* try white-list */ - if (efi_signature_verify_with_sigdb(regs, NULL, db, NULL)) + if (efi_signature_verify_one(regs, NULL, db)) ret = true; else EFI_PRINT("Image is not signed and not found in \"db\" or \"dbx\"\n"); @@ -494,12 +494,13 @@ static bool efi_image_authenticate(void *efi, size_t efi_size) size_t wincerts_len; struct pkcs7_message *msg = NULL; struct efi_signature_store *db = NULL, *dbx = NULL; - struct x509_certificate *cert = NULL; void *new_efi = NULL; u8 *auth, *wincerts_end; size_t new_efi_size, auth_size; bool ret = false; + debug("%s: Enter, %d\n", __func__, ret); + if (!efi_secure_boot_enabled()) return true; @@ -545,7 +546,17 @@ static bool efi_image_authenticate(void *efi, size_t efi_size) goto err; } - /* go through WIN_CERTIFICATE list */ + /* + * go through WIN_CERTIFICATE list + * NOTE: + * We may have multiple signatures either as WIN_CERTIFICATE's + * 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 + */ for (wincert = wincerts, wincerts_end = (u8 *)wincerts + wincerts_len; (u8 *)wincert < wincerts_end; wincert = (WIN_CERTIFICATE *) @@ -595,42 +606,32 @@ static bool efi_image_authenticate(void *efi, size_t efi_size) } /* try black-list first */ - if (efi_signature_verify_with_sigdb(regs, msg, dbx, NULL)) { + if (efi_signature_verify_one(regs, msg, dbx)) { EFI_PRINT("Signature was rejected by \"dbx\"\n"); goto err; } - if (!efi_signature_verify_signers(msg, dbx)) { - EFI_PRINT("Signer was rejected by \"dbx\"\n"); + if (!efi_signature_check_signers(msg, dbx)) { + EFI_PRINT("Signer(s) in \"dbx\"\n"); goto err; - } else { - ret = true; } /* try white-list */ - if (!efi_signature_verify_with_sigdb(regs, msg, db, &cert)) { - EFI_PRINT("Verifying signature with \"db\" failed\n"); + if (!efi_signature_verify_with_sigdb(regs, msg, db, dbx)) { + EFI_PRINT("Signature was not verified by \"db\"\n"); goto err; - } else { - ret = true; - } - - if (!efi_signature_verify_cert(cert, dbx)) { - EFI_PRINT("Certificate was rejected by \"dbx\"\n"); - goto err; - } else { - ret = true; } } + ret = true; err: - x509_free_certificate(cert); efi_sigstore_free(db); efi_sigstore_free(dbx); pkcs7_free_message(msg); free(regs); free(new_efi); + debug("%s: Exit, %d\n", __func__, ret); return ret; } #else -- cgit v1.2.3 From 7926dfb579cb17efc62ede2ce6d5c0a6f7e2f855 Mon Sep 17 00:00:00 2001 From: AKASHI Takahiro Date: Wed, 8 Jul 2020 14:01:57 +0900 Subject: efi_loader: image_loader: add digest-based verification for signed image In case that a type of certificate in "db" or "dbx" is EFI_CERT_X509_SHA256_GUID, it is actually not a certificate which contains a public key for RSA decryption, but a digest of image to be loaded. If the value matches to a value calculated from a given binary image, it is granted for loading. With this patch, common digest check code, which used to be used for unsigned image verification, will be extracted from efi_signature_verify_with_sigdb() into efi_signature_lookup_digest(), and extra step for digest check will be added to efi_image_authenticate(). Signed-off-by: AKASHI Takahiro --- lib/efi_loader/efi_image_loader.c | 44 ++++++++++++++++++++++++++++++++------- 1 file changed, 37 insertions(+), 7 deletions(-) (limited to 'lib/efi_loader/efi_image_loader.c') diff --git a/lib/efi_loader/efi_image_loader.c b/lib/efi_loader/efi_image_loader.c index 058359fc258..b7cf26046e0 100644 --- a/lib/efi_loader/efi_image_loader.c +++ b/lib/efi_loader/efi_image_loader.c @@ -448,16 +448,16 @@ static bool efi_image_unsigned_authenticate(struct efi_image_regions *regs) } /* try black-list first */ - if (efi_signature_verify_one(regs, NULL, dbx)) { - EFI_PRINT("Image is not signed and rejected by \"dbx\"\n"); + if (efi_signature_lookup_digest(regs, dbx)) { + EFI_PRINT("Image is not signed and its digest found in \"dbx\"\n"); goto out; } /* try white-list */ - if (efi_signature_verify_one(regs, NULL, db)) + if (efi_signature_lookup_digest(regs, db)) ret = true; else - EFI_PRINT("Image is not signed and not found in \"db\" or \"dbx\"\n"); + EFI_PRINT("Image is not signed and its digest not found in \"db\" or \"dbx\"\n"); out: efi_sigstore_free(db); @@ -605,6 +605,25 @@ static bool efi_image_authenticate(void *efi, size_t efi_size) continue; } + /* + * NOTE: + * UEFI specification defines two signature types possible + * in signature database: + * a. x509 certificate, where a signature in image is + * a message digest encrypted by RSA public key + * (EFI_CERT_X509_GUID) + * b. bare hash value of message digest + * (EFI_CERT_SHAxxx_GUID) + * + * efi_signature_verify() handles case (a), while + * efi_signature_lookup_digest() handles case (b). + * + * There is a third type: + * c. message digest of a certificate + * (EFI_CERT_X509_SHAAxxx_GUID) + * This type of signature is used only in revocation list + * (dbx) and handled as part of efi_signatgure_verify(). + */ /* try black-list first */ if (efi_signature_verify_one(regs, msg, dbx)) { EFI_PRINT("Signature was rejected by \"dbx\"\n"); @@ -616,11 +635,22 @@ static bool efi_image_authenticate(void *efi, size_t efi_size) goto err; } - /* try white-list */ - if (!efi_signature_verify_with_sigdb(regs, msg, db, dbx)) { - EFI_PRINT("Signature was not verified by \"db\"\n"); + if (efi_signature_lookup_digest(regs, dbx)) { + EFI_PRINT("Image's digest was found in \"dbx\"\n"); goto err; } + + /* try white-list */ + if (efi_signature_verify_with_sigdb(regs, msg, db, dbx)) + continue; + + debug("Signature was not verified by \"db\"\n"); + + if (efi_signature_lookup_digest(regs, db)) + continue; + + debug("Image's digest was not found in \"db\" or \"dbx\"\n"); + goto err; } ret = true; -- cgit v1.2.3 From 39a75f5af139eaa53758a8cb0e0788cfafdaf54c Mon Sep 17 00:00:00 2001 From: Heinrich Schuchardt Date: Tue, 7 Jul 2020 07:23:44 +0200 Subject: efi_loader: wrong printf format in efi_image_parse MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Commit 1b6c08548c85 ("efi_loader: image_loader: replace debug to EFI_PRINT") leads to a build warning on 32bit systems: lib/efi_loader/efi_image_loader.c: In function ‘efi_image_parse’: include/efi_loader.h:123:8: warning: format ‘%lu’ expects argument of type ‘long unsigned int’, but argument 8 has type ‘size_t’ {aka ‘unsigned int’} [-Wformat=] Use %zu for printing size_t. Fixes: 1b6c08548c85 ("efi_loader: image_loader: replace debug to EFI_PRINT") Signed-off-by: Heinrich Schuchardt --- lib/efi_loader/efi_image_loader.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'lib/efi_loader/efi_image_loader.c') diff --git a/lib/efi_loader/efi_image_loader.c b/lib/efi_loader/efi_image_loader.c index b7cf26046e0..fef0bb870c6 100644 --- a/lib/efi_loader/efi_image_loader.c +++ b/lib/efi_loader/efi_image_loader.c @@ -382,7 +382,7 @@ 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: %lu\n", + EFI_PRINT("extra data for hash: %zu\n", len - (bytes_hashed + authsz)); efi_image_region_add(regs, efi + bytes_hashed, efi + len - authsz, 0); -- cgit v1.2.3