[PATCH v3 04/16] efi_loader: add signature database parser
AKASHI Takahiro
takahiro.akashi at linaro.org
Mon Dec 9 07:00:44 CET 2019
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 3ca68f9bbb6e..3b3618e0be24 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -720,6 +720,9 @@ 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 823d3311e010..98302e1ab3d3 100644
--- a/lib/efi_loader/efi_signature.c
+++ b/lib/efi_loader/efi_signature.c
@@ -581,4 +581,230 @@ 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) {
+ 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 */
--
2.24.0
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