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Yubico · Feb 2, 2024 · be38388 · be38388
1 parent 3b8e322
commit be38388
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Showing 4 changed files with 74 additions and 18 deletions.
diff --git a/src/cbor.c b/src/cbor.c
@@ -1386,12 +1386,31 @@ cbor_decode_assert_authdata(const cbor_item_t *item, fido_blob_t *authdata_cbor,
 static int
 decode_x5c(const cbor_item_t *item, void *arg)
 {
-	fido_blob_t *x5c = arg;
+	fido_blob_array_t *x5c = arg;
+	fido_blob_t *list_ptr;
+	fido_blob_t blob;
 
-	if (x5c->len)
-		return (0); /* ignore */
+	memset(&blob, 0, sizeof(blob));
 
-	return (fido_blob_decode(item, x5c));
+	if (x5c->len == SIZE_MAX) {
+		fido_log_debug("%s: len", __func__);
+		return (-1);
+	}
+	if (fido_blob_decode(item, &blob) != 0) {
+		fido_log_debug("%s: fido_blob_decode", __func__);
+		return (-1);
+	}
+	if ((list_ptr = recallocarray(x5c->ptr, x5c->len, x5c->len + 1,
+	    sizeof(blob))) == NULL) {
+		fido_log_debug("%s: recallocarray", __func__);
+		fido_blob_reset(&blob);
+		return (-1);
+	}
+
+	list_ptr[x5c->len++] = blob;
+	x5c->ptr = list_ptr;
+
+	return (0);
 }
 
 static int
@@ -1427,6 +1446,7 @@ decode_attstmt_entry(const cbor_item_t *key, const cbor_item_t *val, void *arg)
 			goto out;
 		}
 	} else if (!strcmp(name, "x5c")) {
+		fido_free_blob_array(&attstmt->x5c);  /* XXX */
 		if (cbor_isa_array(val) == false ||
 		    cbor_array_is_definite(val) == false ||
 		    cbor_array_iter(val, &attstmt->x5c, decode_x5c) < 0) {

diff --git a/src/cred.c b/src/cred.c
@@ -279,20 +279,26 @@ get_signed_hash_u2f(fido_blob_t *dgst, const unsigned char *rp_id,
 static int
 verify_attstmt(const fido_blob_t *dgst, const fido_attstmt_t *attstmt)
 {
+	const fido_blob_t *blob;
 	BIO		*rawcert = NULL;
 	X509		*cert = NULL;
 	EVP_PKEY	*pkey = NULL;
 	int		 ok = -1;
 
+	/* XXX: only leaf certificate */
+	if ((blob = attstmt->x5c.ptr) == NULL || blob->ptr == NULL) {
+		fido_log_debug("%s: x5c", __func__);
+		return (-1);
+	}
+
 	/* openssl needs ints */
-	if (attstmt->x5c.len > INT_MAX) {
-		fido_log_debug("%s: x5c.len=%zu", __func__, attstmt->x5c.len);
+	if (blob->len > INT_MAX) {
+		fido_log_debug("%s: blob.len=%zu", __func__, blob->len);
 		return (-1);
 	}
 
 	/* fetch key from x509 */
-	if ((rawcert = BIO_new_mem_buf(attstmt->x5c.ptr,
-	    (int)attstmt->x5c.len)) == NULL ||
+	if ((rawcert = BIO_new_mem_buf(blob->ptr, (int)blob->len)) == NULL ||
 	    (cert = d2i_X509_bio(rawcert, NULL)) == NULL ||
 	    (pkey = X509_get_pubkey(cert)) == NULL) {
 		fido_log_debug("%s: x509 key", __func__);
@@ -543,7 +549,7 @@ fido_cred_clean_attstmt(fido_attstmt_t *attstmt)
 	fido_blob_reset(&attstmt->certinfo);
 	fido_blob_reset(&attstmt->pubarea);
 	fido_blob_reset(&attstmt->cbor);
-	fido_blob_reset(&attstmt->x5c);
+	fido_free_blob_array(&attstmt->x5c);
 	fido_blob_reset(&attstmt->sig);
 
 	memset(attstmt, 0, sizeof(*attstmt));
@@ -688,9 +694,19 @@ fido_cred_set_id(fido_cred_t *cred, const unsigned char *ptr, size_t len)
 int
 fido_cred_set_x509(fido_cred_t *cred, const unsigned char *ptr, size_t len)
 {
-	if (fido_blob_set(&cred->attstmt.x5c, ptr, len) < 0)
+	fido_blob_t *blob;
+
+	if ((blob = fido_blob_new()) == NULL)
+		return (FIDO_ERR_INTERNAL);
+
+	if (fido_blob_set(blob, ptr, len) < 0)
 		return (FIDO_ERR_INVALID_ARGUMENT);
 
+	/* compat: sets only a leaf certificate */
+	fido_free_blob_array(&cred->attstmt.x5c);
+	cred->attstmt.x5c.ptr = blob;
+	cred->attstmt.x5c.len = 1;
+
 	return (FIDO_OK);
 }
 
@@ -1027,16 +1043,34 @@ fido_cred_clientdata_hash_len(const fido_cred_t *cred)
 	return (cred->cdh.len);
 }
 
+const unsigned char *
+fido_cred_x5c_cert_ptr(const fido_cred_t *cred, size_t idx)
+{
+	if (idx >= cred->attstmt.x5c.len)
+		return NULL;
+
+	return (cred->attstmt.x5c.ptr[idx].ptr);
+}
+
 const unsigned char *
 fido_cred_x5c_ptr(const fido_cred_t *cred)
 {
-	return (cred->attstmt.x5c.ptr);
+	return (fido_cred_x5c_cert_ptr(cred, 0));
+}
+
+size_t
+fido_cred_x5c_cert_len(const fido_cred_t *cred, size_t idx)
+{
+	if (idx >= cred->attstmt.x5c.len)
+		return 0;
+
+	return (cred->attstmt.x5c.ptr[idx].len);
 }
 
 size_t
 fido_cred_x5c_len(const fido_cred_t *cred)
 {
-	return (cred->attstmt.x5c.len);
+	return (fido_cred_x5c_cert_len(cred, 0));
 }
 
 const unsigned char *

diff --git a/src/fido.h b/src/fido.h
@@ -124,6 +124,7 @@ const unsigned char *fido_cred_pubkey_ptr(const fido_cred_t *);
 const unsigned char *fido_cred_sig_ptr(const fido_cred_t *);
 const unsigned char *fido_cred_user_id_ptr(const fido_cred_t *);
 const unsigned char *fido_cred_x5c_ptr(const fido_cred_t *);
+const unsigned char *fido_cred_x5c_cert_ptr(const fido_cred_t *, size_t);
 
 int fido_assert_allow_cred(fido_assert_t *, const unsigned char *, size_t);
 int fido_assert_empty_allow_list(fido_assert_t *);
@@ -226,6 +227,7 @@ size_t fido_cred_pubkey_len(const fido_cred_t *);
 size_t fido_cred_sig_len(const fido_cred_t *);
 size_t fido_cred_user_id_len(const fido_cred_t *);
 size_t fido_cred_x5c_len(const fido_cred_t *);
+size_t fido_cred_x5c_cert_len(const fido_cred_t *, size_t);
 
 uint8_t  fido_assert_flags(const fido_assert_t *, size_t);
 uint32_t fido_assert_sigcount(const fido_assert_t *, size_t);

diff --git a/src/fido/types.h b/src/fido/types.h
@@ -140,12 +140,12 @@ typedef struct fido_attcred {
 } fido_attcred_t;
 
 typedef struct fido_attstmt {
-	fido_blob_t certinfo; /* tpm attestation TPMS_ATTEST structure */
-	fido_blob_t pubarea;  /* tpm attestation TPMT_PUBLIC structure */
-	fido_blob_t cbor;     /* cbor-encoded attestation statement */
-	fido_blob_t x5c;      /* attestation certificate */
-	fido_blob_t sig;      /* attestation signature */
-	int         alg;      /* attestation algorithm (cose) */
+	fido_blob_t certinfo;  /* tpm attestation TPMS_ATTEST structure */
+	fido_blob_t pubarea;   /* tpm attestation TPMT_PUBLIC structure */
+	fido_blob_t cbor;      /* cbor-encoded attestation statement */
+	fido_blob_array_t x5c; /* attestation certificate chain */
+	fido_blob_t sig;       /* attestation signature */
+	int         alg;       /* attestation algorithm (cose) */
 } fido_attstmt_t;
 
 typedef struct fido_rp {