pivy-tool: add delete-cert command

Author: arekinath

piv.c

@@ -3135,17 +3135,21 @@ piv_write_cert(struct piv_token *pk, enum piv_slotid slotid,
 		    "%02x", slotid));
 	}
 
-	tlv = tlv_init_write();
-	tlv_push(tlv, 0x70);
-	tlv_write(tlv, data, datalen);
-	tlv_pop(tlv);
-	tlv_push(tlv, 0x71);
-	tlv_write_byte(tlv, (uint8_t)flags);
-	tlv_pop(tlv);
+	if (data != NULL && datalen > 0) {
+		tlv = tlv_init_write();
+		tlv_push(tlv, 0x70);
+		tlv_write(tlv, data, datalen);
+		tlv_pop(tlv);
+		tlv_push(tlv, 0x71);
+		tlv_write_byte(tlv, (uint8_t)flags);
+		tlv_pop(tlv);
 
-	err = piv_write_file(pk, tag, tlv_buf(tlv), tlv_len(tlv));
+		err = piv_write_file(pk, tag, tlv_buf(tlv), tlv_len(tlv));
 
-	tlv_free(tlv);
+		tlv_free(tlv);
+	} else {
+		err = piv_write_file(pk, tag, NULL, 0);
+	}
 
 	return (err);
 }

pivy-tool.c

@@ -1734,6 +1734,62 @@ cmd_cert(uint slotid)
 	return (ERRF_OK);
 }
 
+static errf_t *
+cmd_delete_cert(uint slotid)
+{
+	errf_t *err;
+
+	assert_slotid(slotid);
+
+	if ((err = piv_txn_begin(selk)))
+		errfx(1, err, "failed to open transaction");
+	assert_select(selk);
+admin_again:
+	err = piv_auth_admin(selk, admin_key, key_length, key_alg);
+	if (err && (errf_caused_by(err, "PermissionError") ||
+	    errf_caused_by(err, "ArgumentError")) &&
+	    admin_key == DEFAULT_ADMIN_KEY) {
+		errf_free(err);
+		err = try_pinfo_admin_key(selk);
+		if (err == ERRF_OK)
+			goto admin_again;
+	}
+
+	if (err == ERRF_OK)
+		err = piv_write_cert(selk, slotid, NULL, 0, PIV_COMP_NONE);
+
+	if (err == ERRF_OK && slotid >= 0x82 && slotid <= 0x95 &&
+	    piv_token_keyhistory_oncard(selk) >= slotid - 0x82) {
+		uint oncard, offcard;
+		const char *url;
+
+		oncard = piv_token_keyhistory_oncard(selk);
+		offcard = piv_token_keyhistory_offcard(selk);
+		url = piv_token_offcard_url(selk);
+
+		if (oncard > 0)
+			--oncard;
+
+		err = piv_write_keyhistory(selk, oncard, offcard, url);
+
+		if (err) {
+			warnfx(err, "failed to update key "
+			    "history object with new cert, trying to "
+			    "continue anyway...");
+			err = ERRF_OK;
+		}
+	}
+
+	piv_txn_end(selk);
+
+	if (err) {
+		err = errf("write_cert", err, "failed to delete cert");
+		return (err);
+	}
+
+	return (ERRF_OK);
+}
+
 static errf_t *
 cmd_write_cert(uint slotid)
 {
@@ -2784,6 +2840,7 @@ usage(void)
 	    "                         and replaces the cert in the given slot\n"
 	    "  req-cert <slot>        Generates an X.509 CSR for the key in\n"
 	    "                         the given slot (for user auth)\n"
+	    "  delete-cert <slot>     Clears the certificate from the given slot\n"
 	    "  change-pin             Changes the PIV PIN\n"
 	    "  change-puk             Changes the PIV PUK\n"
 	    "  reset-pin              Resets the PIN using the PUK\n"
@@ -3430,6 +3487,28 @@ main(int argc, char *argv[])
 			override = piv_force_slot(selk, slotid, overalg);
 		err = cmd_write_cert(slotid);
 
+	} else if (strcmp(op, "delete-cert") == 0) {
+		enum piv_slotid slotid;
+
+		if (optind >= argc) {
+			warnx("not enough arguments for %s (slot required)",
+			    op);
+			usage();
+		}
+		err = piv_slotid_from_string(argv[optind++], &slotid);
+		if (err != ERRF_OK)
+			errfx(EXIT_BAD_ARGS, err, "failed to parse slot id");
+
+		if (optind < argc) {
+			warnx("too many arguments for %s", op);
+			usage();
+		}
+
+		check_select_key();
+		if (hasover)
+			override = piv_force_slot(selk, slotid, overalg);
+		err = cmd_delete_cert(slotid);
+
 	} else if (strcmp(op, "req-cert") == 0) {
 		enum piv_slotid slotid;