tee-supplicant: send READY=1 notification to systemd

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

Signed-off-by: Ayoub Zaki <[email protected]>
Acked-by: Jerome Forissier <[email protected]>
Tested-by: Mikko Rapeli <[email protected]>

tee-supplicant/CMakeLists.txt

@@ -28,6 +28,7 @@ set(SRC
 	src/hmac_sha2.c
 	src/rpmb.c
 	src/sha2.c
+	src/sd_notify.c
 	src/tee_supp_fs.c
 	src/tee_supplicant.c
 	src/teec_ta_load.c

tee-supplicant/Makefile

@@ -18,7 +18,8 @@ TEES_SRCS	:= tee_supplicant.c \
 		   teec_ta_load.c \
 		   tee_supp_fs.c \
 		   rpmb.c \
-		   handle.c
+		   handle.c \
+		   sd_notify.c
 
 ifeq ($(CFG_GP_SOCKETS),y)
 TEES_SRCS 	+= tee_socket.c

tee-supplicant/src/sd_notify.c

@@ -0,0 +1,93 @@
+// SPDX-License-Identifier: MIT-0
+/*
+ * The code below is imported from:
+ * https://www.freedesktop.org/software/systemd/man/devel/sd_notify.html#Standalone%20Implementations
+ */
+
+#define _GNU_SOURCE 1
+#include <string.h>
+#include <errno.h>
+#include <inttypes.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "sd_notify.h"
+
+#define _cleanup_(f) __attribute__((cleanup(f)))
+
+static void closep(int *fd)
+{
+    if (!fd || *fd < 0)
+        return;
+
+    close(*fd);
+    *fd = -1;
+}
+
+static int notify(const char *message)
+{
+    union sockaddr_union {
+        struct sockaddr sa;
+        struct sockaddr_un sun;
+    } socket_addr = {
+        .sun.sun_family = AF_UNIX,
+    };
+
+    ssize_t written = 0;
+    size_t path_length, message_length = 0;
+    _cleanup_(closep) int fd = -1;
+    const char *socket_path = NULL;
+
+    /* Verify the argument first */
+    if (!message)
+       return -EINVAL;
+
+    message_length = strlen(message);
+    if (message_length == 0)
+        return -EINVAL;
+
+    /* If the variable is not set, the protocol is a noop */
+    socket_path = getenv("NOTIFY_SOCKET");
+    if (!socket_path)
+       return 0; /* Not set? Nothing to do */
+
+    /* Only AF_UNIX is supported, with path or abstract sockets */
+    if (socket_path[0] != '/' && socket_path[0] != '@')
+        return -EAFNOSUPPORT;
+
+    path_length = strlen(socket_path);
+    /* Ensure there is room for NULL byte */
+    if (path_length >= sizeof(socket_addr.sun.sun_path))
+        return -E2BIG;
+
+    memcpy(socket_addr.sun.sun_path, socket_path, path_length);
+
+    /* Support for abstract socket */
+    if (socket_addr.sun.sun_path[0] == '@')
+        socket_addr.sun.sun_path[0] = 0;
+
+    fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0);
+    if (fd < 0)
+        return -errno;
+
+    if (connect(fd, &socket_addr.sa, offsetof(struct sockaddr_un, sun_path) + path_length) != 0)
+        return -errno;
+
+    written = write(fd, message, message_length);
+    if (written != (ssize_t) message_length)
+        return written < 0 ? -errno : -EPROTO;
+
+    return 1; /* Notified! */
+}
+
+int sd_notify_ready(void)
+{
+    return notify("READY=1");
+}

tee-supplicant/src/sd_notify.h

@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: MIT-0
+/*
+ * The code below is imported from:
+ * https://www.freedesktop.org/software/systemd/man/devel/sd_notify.html#Standalone%20Implementations
+ */
+#ifndef SD_NOTIFY_H
+#define SD_NOTIFY_H
+
+int sd_notify_ready(void);
+
+#endif /* SD_NOTIFY_H */

tee-supplicant/src/tee_supplicant.c

@@ -53,6 +53,7 @@
 #include <tee_socket.h>
 #include <tee_supp_fs.h>
 #include <tee_supplicant.h>
+#include <sd_notify.h>
 #include <unistd.h>
 
 #include "optee_msg_supplicant.h"
@@ -923,6 +924,11 @@ int main(int argc, char *argv[])
 		}
 	}
 
+	/* we are set here notify systemd */
+	e = sd_notify_ready();
+	if(e < 0)
+		fprintf(stderr, "sd_notify_ready() failed: %s\n", strerror(-e));
+
 	if (daemonize) {
 		/* Release parent */
 		if (write(pipefd[1], "", 1) != 1) {