[PATCH v7 03/17] efi_loader: add signature database parser
Heinrich Schuchardt
xypron.glpk at gmx.de
Fri Apr 17 20:05:41 CEST 2020
On 4/14/20 4:51 AM, AKASHI Takahiro wrote:
> efi_signature_parse_sigdb() is a helper function will be used to parse
> signature database variable and instantiate a signature store structure
> in later patches.
>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
> ---
> include/efi_loader.h | 3 +
> lib/efi_loader/efi_signature.c | 226 +++++++++++++++++++++++++++++++++
> 2 files changed, 229 insertions(+)
>
> diff --git a/include/efi_loader.h b/include/efi_loader.h
> index 8cf85d2fb7e2..fea2ead02e93 100644
> --- a/include/efi_loader.h
> +++ b/include/efi_loader.h
> @@ -750,6 +750,9 @@ bool efi_signature_verify_with_sigdb(struct efi_image_regions *regs,
> efi_status_t efi_image_region_add(struct efi_image_regions *regs,
> const void *start, const void *end,
> int nocheck);
> +
> +void efi_sigstore_free(struct efi_signature_store *sigstore);
> +struct efi_signature_store *efi_sigstore_parse_sigdb(u16 *name);
> #endif /* CONFIG_EFI_SECURE_BOOT */
>
> #else /* CONFIG_IS_ENABLED(EFI_LOADER) */
> diff --git a/lib/efi_loader/efi_signature.c b/lib/efi_loader/efi_signature.c
> index 23dac94c0593..2d1f38980e5f 100644
> --- a/lib/efi_loader/efi_signature.c
> +++ b/lib/efi_loader/efi_signature.c
> @@ -580,4 +580,230 @@ efi_status_t efi_image_region_add(struct efi_image_regions *regs,
>
> 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) {
This code is unreachable (as indicated by cppcheck).
Please, send a follow-up patch.
Best regards
Heinrich
> + 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 */
>
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