From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heinrich Schuchardt Date: Fri, 3 Jul 2020 12:56:55 +0200 Subject: [PATCH v2 06/17] efi_loader: image_loader: add a check against certificate type of authenticode In-Reply-To: <20200609050947.17861-7-takahiro.akashi@linaro.org> References: <20200609050947.17861-1-takahiro.akashi@linaro.org> <20200609050947.17861-7-takahiro.akashi@linaro.org> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 09.06.20 07:09, AKASHI Takahiro wrote: > 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(-) > > diff --git a/lib/efi_loader/efi_image_loader.c b/lib/efi_loader/efi_image_loader.c > index 5b00fea2f113..38b2c24ab1d6 100644 > --- a/lib/efi_loader/efi_image_loader.c > +++ b/lib/efi_loader/efi_image_loader.c > @@ -484,7 +484,8 @@ 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()) > @@ -533,21 +534,52 @@ 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; Shouldn't you compare the end of the current certificate to wincerts_end? ((u8 *)wincert + ALIGN(wincert->dwLength, 8))) <= wincerts_end But you doing such a comparison anyway two lines below. So there is no need to duplicate the test here. > + wincert = (WIN_CERTIFICATE *) > + ((u8 *)wincert + ALIGN(wincert->dwLength, 8))) { > + if ((u8 *)wincert + sizeof(*wincert) >= wincerts_end) > + break; Why is this >= and not >? Best regards Heinrich > + > + 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 */ >