From 72ea9211f1e0e02725311f7fe15eee9d3eb5b888 Mon Sep 17 00:00:00 2001
From: Sangyoon Jang <s89.jang@samsung.com>
Date: Mon, 12 Sep 2016 13:48:08 +0900
Subject: [PATCH] Add auth checking at signal agent

Only root or 'app_fw' user can send to agent.

Change-Id: If3ec8662fa9290af7f0d7ffc22b73b39dcfb9a4f
Signed-off-by: Sangyoon Jang <s89.jang@samsung.com>
---
 installer/pkgmgr_installer_signal_agent.c | 45 +++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/installer/pkgmgr_installer_signal_agent.c b/installer/pkgmgr_installer_signal_agent.c
index 5c49f9a..ca43fad 100644
--- a/installer/pkgmgr_installer_signal_agent.c
+++ b/installer/pkgmgr_installer_signal_agent.c
@@ -15,6 +15,8 @@
  *
  */
 
+#define _GNU_SOURCE
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -24,6 +26,7 @@
 #include <sys/types.h>
 #include <sys/un.h>
 #include <linux/limits.h>
+#include <pwd.h>
 
 #include <glib.h>
 #include <glib-unix.h>
@@ -40,6 +43,8 @@
 #define LOG_TAG "PKGMGR_INSTALLER_SIGNAL_AGENT"
 
 #define BUFMAX 4096
+#define PWBUFSIZE sysconf(_SC_GETPW_R_SIZE_MAX)
+#define APPFW_USERNAME "app_fw"
 
 static int server_fd;
 static GMainLoop *loop;
@@ -141,6 +146,41 @@ static gboolean __quit(gpointer user_data)
 	return FALSE;
 }
 
+static int __check_authority(int fd)
+{
+	int r;
+	struct ucred cr;
+	socklen_t len;
+	struct passwd pwd;
+	struct passwd *pwd_r;
+	char buf[PWBUFSIZE];
+
+	len = sizeof(struct ucred);
+	r = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cr, &len);
+	if (r != 0) {
+		LOGE("getsockopt failed: %d", errno);
+		return -1;
+	}
+
+	/* allow root user */
+	if (cr.uid == 0)
+		return 0;
+
+	r = getpwuid_r(cr.uid, &pwd, buf, sizeof(buf), &pwd_r);
+	if (r != 0 || pwd_r == NULL) {
+		LOGE("getpwuid failed: %d", r);
+		return -1;
+	}
+
+	/* only app_fw user can send signal to agent */
+	if (strcmp(pwd_r->pw_name, APPFW_USERNAME) != 0) {
+		LOGE("unauthorized client");
+		return -1;
+	}
+
+	return 0;
+}
+
 /**
  * packet format:
  * +----------------+-------------+-----------+-------------------+
@@ -166,6 +206,11 @@ static gboolean __handle_signal(gint fd, GIOCondition cond, gpointer user_data)
 		return FALSE;
 	}
 
+	if (__check_authority(clifd)) {
+		close(clifd);
+		return TRUE;
+	}
+
 	r = recv(clifd, buf, sizeof(size_t) + sizeof(gsize), 0);
 	if (r < 0) {
 		LOGE("recv failed: %d", errno);
-- 
2.34.1