From 1919000c897ccf0f88a5584faf3a2efc1a7a3c30 Mon Sep 17 00:00:00 2001
From: Sebastien RAILLET <sebastien.raillet@marelli.com>
Date: Wed, 22 Sep 2021 16:54:31 +0200
Subject: dlt-daemon: create sockets using "android way"

* Before this commit, dlt-daemon sockets were created inside
/data/local/tmp. This works but have many drawbacks:
    - /data/local/tmp isn't always a tmpfs depending of the android
    system you have. Means sockets are potentially created on a
    filesystem which binds to a real device
    - as the sockets are created by the dlt-daemon itself, this
    prevent the usage of specific SELinux labels / contexts as
    they will inherit the label / context from its parent
    location (e.g the ones from /data/local/tmp). This prevent a
    fine control of the SELinux label / context that you would like
    to apply on them

* This commit adapts the dlt-daemon in such way:
    - application and control sockets are now created inside
    /dev/socket which is the standard path for sockets on android
    - these sockets are now created by init (see dlt-daemon.rc) and
    their fds are recovered by dlt-daemon through a specific android
    API (dlt_daemon_unix_android_get_socket). If the fds can't be
    recovered, we fallback to the previous mechanism by creating
    by ourself the sockets (even if this will prevent SELinux
    label / context on this socket)
    - all these modifications have been put under compilation flag
    for android

Signed-off-by: Sebastien RAILLET <sebastien.raillet@marelli.com>
---
 src/daemon/dlt_daemon_unix_socket.c | 44 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 43 insertions(+), 1 deletion(-)

(limited to 'src/daemon/dlt_daemon_unix_socket.c')

diff --git a/src/daemon/dlt_daemon_unix_socket.c b/src/daemon/dlt_daemon_unix_socket.c
index b58beb1..ea889b0 100644
--- a/src/daemon/dlt_daemon_unix_socket.c
+++ b/src/daemon/dlt_daemon_unix_socket.c
@@ -28,17 +28,59 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sys/un.h>
-#include <sys/socket.h>
+#if defined(ANDROID)
+#   include <cutils/sockets.h> /* for android_get_control_socket() */
+#   include <libgen.h> /* for basename() */
+#else
+#   include <sys/socket.h> /* for socket(), connect(), (), and recv() */
+#endif
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <syslog.h>
 #include <errno.h>
+
 #include "dlt-daemon.h"
 #include "dlt_common.h"
 #include "dlt-daemon_cfg.h"
 #include "dlt_daemon_socket.h"
 #include "dlt_daemon_unix_socket.h"
 
+#ifdef ANDROID
+DltReturnValue dlt_daemon_unix_android_get_socket(int *sock, const char *sock_path)
+{
+    DltReturnValue ret = DLT_RETURN_OK;
+
+    if ((sock == NULL) || (sock_path == NULL)) {
+        dlt_log(LOG_ERR, "dlt_daemon_unix_android_get_socket: arguments invalid");
+        ret = DLT_RETURN_WRONG_PARAMETER;
+    }
+    else {
+        const char* sock_name = basename(sock_path);
+        if (sock_name == NULL) {
+            dlt_log(LOG_WARNING,
+                    "dlt_daemon_unix_android_get_socket: can't get socket name from its path");
+            ret = DLT_RETURN_ERROR;
+        }
+        else {
+            *sock = android_get_control_socket(sock_name);
+            if (*sock < 0) {
+                dlt_log(LOG_WARNING,
+                        "dlt_daemon_unix_android_get_socket: can get socket from init");
+                ret = DLT_RETURN_ERROR;
+            }
+            else {
+                if (listen(*sock, 1) == -1) {
+                    dlt_vlog(LOG_WARNING, "unix socket: listen error: %s", strerror(errno));
+                    ret = DLT_RETURN_ERROR;
+                }
+            }
+        }
+    }
+
+    return ret;
+}
+#endif
+
 int dlt_daemon_unix_socket_open(int *sock, char *sock_path, int type, int mask)
 {
     struct sockaddr_un addr;
-- 
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