From c7649f82c6ace3666240bf5a192f730a4f8271f6 Mon Sep 17 00:00:00 2001
From: Ayoub Zaki <ayoub.zaki@embetrix.com>
Date: Thu, 30 May 2024 13:36:59 +0200
Subject: [PATCH] Add option to send READY=1 notification to systemd after
 tee-supplicant is setup

This option is very useful when tee-supplicant is started from systemd and can used with Type=notify to signal readiness

Note: this cannot be used with daemonize option as it the process is forking
---
 flags.mk                            |  2 ++
 tee-supplicant/src/tee_supplicant.c | 30 +++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/flags.mk b/flags.mk
index be4088c1..31d36785 100644
--- a/flags.mk
+++ b/flags.mk
@@ -9,6 +9,8 @@ PKG_CONFIG	?= $(CROSS_COMPILE)pkg-config
 
 C_COMPILER=$(shell readlink -f $$(which $(CC)))
 
+override LDFLAGS += -ldl
+
 override CFLAGS += -Wall -Wbad-function-cast -Wcast-align \
 		   -Werror-implicit-function-declaration -Wextra \
 		   -Wfloat-equal -Wformat-nonliteral -Wformat-security \
diff --git a/tee-supplicant/src/tee_supplicant.c b/tee-supplicant/src/tee_supplicant.c
index 98dec3ce..94587c94 100644
--- a/tee-supplicant/src/tee_supplicant.c
+++ b/tee-supplicant/src/tee_supplicant.c
@@ -54,6 +54,7 @@
 #include <tee_supp_fs.h>
 #include <tee_supplicant.h>
 #include <unistd.h>
+#include <dlfcn.h>
 
 #include "optee_msg_supplicant.h"
 
@@ -493,6 +494,8 @@ static int usage(int status)
 	fprintf(stderr, "\t-h, --help: this help\n");
 	fprintf(stderr, "\t-d, --daemonize: run as a daemon (fork and return "
 			"after child has opened the TEE device or on error)\n");
+	fprintf(stderr, "\t-n, --sdnotify: signal READY=1 to systemd "
+			"after tee-supplicant is setup)\n");
 	fprintf(stderr, "\t-f, --fs-parent-path: secure fs parent path [%s]\n",
 			supplicant_params.fs_parent_path);
 	fprintf(stderr, "\t-l, --ta-path: TA load path\n");
@@ -819,6 +822,7 @@ int main(int argc, char *argv[])
 	struct thread_arg arg = { .fd = -1 };
 	int pipefd[2] = { 0, };
 	bool daemonize = false;
+	bool sdnotify = false;
 	char *dev = NULL;
 	int e = 0;
 	int long_index = 0;
@@ -835,6 +839,7 @@ int main(int argc, char *argv[])
 		/* long name      | has argument  | flag | short value */
 		{ "help",            no_argument,       0, 'h' },
 		{ "daemonize",       no_argument,       0, 'd' },
+		{ "sdnotify",        no_argument,       0, 'n' },
 		{ "fs-parent-path",  required_argument, 0, 'f' },
 		{ "ta-path",         required_argument, 0, 'l' },
 		{ "ta-dir",          required_argument, 0, 't' },
@@ -852,6 +857,9 @@ int main(int argc, char *argv[])
 			case 'd':
 				daemonize = true;
 				break;
+			case 'n':
+				sdnotify = true;
+				break;
 			case 'f':
 				supplicant_params.fs_parent_path = optarg;
 				break;
@@ -923,6 +931,28 @@ int main(int argc, char *argv[])
 		}
 	}
 
+	if (sdnotify) {
+		/* we are set here notify systemd */
+		int(*__sd_notify__)();
+		void *systemd = dlopen("libsystemd.so", RTLD_LAZY);
+		if (systemd) {
+			*(int**)(&__sd_notify__) = dlsym(systemd, "sd_notify");
+			if (__sd_notify__) {
+					int ret = __sd_notify__(0, "READY=1");
+					if (ret <= 0) {
+						fprintf(stderr, "sd_notify failed: %d\n", ret);
+					}
+			}
+			else {
+				fprintf(stderr, "Couldn't find sd_notify symbol: %s\n", dlerror());
+			}
+			dlclose(systemd);
+		}
+		else {
+			fprintf(stderr, "Couldn't open libsystemd.so: %s\n", dlerror());
+		}		
+	}
+
 	if (daemonize) {
 		/* Release parent */
 		if (write(pipefd[1], "", 1) != 1) {