[PATCH RFC 11/17] console: ratp: add security config option

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

For secure systems that disable the regular console, RATP should be
disabled as well, so add an option to do so.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 Sconfig            |  1 +
 common/Sconfig     |  9 +++++++++
 common/console.c   |  4 +++-
 common/ratp/ratp.c | 17 +++++++++++++++++
 4 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 common/Sconfig

diff --git a/Sconfig b/Sconfig
index 93f5760ad96f..899a1fb5783f 100644
--- a/Sconfig
+++ b/Sconfig
@@ -5,4 +5,5 @@ mainmenu "Barebox/$(ARCH) Security Configuration"
 source "scripts/Sconfig.include"
 
 source "security/Sconfig"
+source "common/Sconfig"
 source "commands/Sconfig"
diff --git a/common/Sconfig b/common/Sconfig
new file mode 100644
index 000000000000..479ac5cdf2e5
--- /dev/null
+++ b/common/Sconfig
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+menu "General Settings"
+
+config RATP
+	bool "Allow remote control via RATP"
+	depends on $(kconfig-enabled,CONSOLE_RATP)
+
+endmenu
diff --git a/common/console.c b/common/console.c
index dc552e4c5dac..65e4f1f85224 100644
--- a/common/console.c
+++ b/common/console.c
@@ -5,6 +5,7 @@
  */
 
 #include <config.h>
+#include <security/config.h>
 #include <common.h>
 #include <stdarg.h>
 #include <malloc.h>
@@ -492,7 +493,8 @@ static int getc_raw(void)
 			if (cdev->tstc(cdev)) {
 				int ch = cdev->getc(cdev);
 
-				if (IS_ENABLED(CONFIG_RATP) && ch == 0x01) {
+				if (IS_ENABLED(CONFIG_RATP) && ch == 0x01 &&
+				    IS_ALLOWED(SCONFIG_RATP)) {
 					barebox_ratp(cdev);
 					return -1;
 				}
diff --git a/common/ratp/ratp.c b/common/ratp/ratp.c
index 2906f5a09098..f2735fa88531 100644
--- a/common/ratp/ratp.c
+++ b/common/ratp/ratp.c
@@ -14,6 +14,7 @@
 #define pr_fmt(fmt) "barebox-ratp: " fmt
 
 #include <common.h>
+#include <security/config.h>
 #include <command.h>
 #include <malloc.h>
 #include <init.h>
@@ -46,6 +47,7 @@ struct ratp_ctx {
 
 	struct ratp_bb_pkt *fs_rx;
 
+	struct sconfig_notifier_block sconfig_notifier;
 	struct poller_struct poller;
 	struct work_queue wq;
 
@@ -456,11 +458,22 @@ static void ratp_work_cancel(struct work_struct *w)
 	free(rw);
 }
 
+static void barebox_ratp_sconfig_update(struct sconfig_notifier_block *nb,
+				       enum security_config_option opt,
+				       bool allowed)
+{
+	if (!allowed && ratp_ctx)
+		ratp_unregister(ratp_ctx);
+}
+
 int barebox_ratp(struct console_device *cdev)
 {
 	int ret;
 	struct ratp_ctx *ctx;
 
+	if (!IS_ALLOWED(SCONFIG_RATP))
+		return -EPERM;
+
 	if (!cdev->getc || !cdev->putc)
 		return -EINVAL;
 
@@ -515,6 +528,10 @@ int barebox_ratp(struct console_device *cdev)
 	console_set_active(&ctx->ratp_console, CONSOLE_STDOUT | CONSOLE_STDERR |
 			CONSOLE_STDIN);
 
+	sconfig_register_handler_filtered(&ctx->sconfig_notifier,
+					  barebox_ratp_sconfig_update,
+					  SCONFIG_RATP);
+
 	return 0;
 
 out:
-- 
2.39.5