Refactor handling of platforms without user/group settings (Android)

7 files changed, 57 insertions, 16 deletions

diff --git a/cmake/config.cmake b/cmake/config.cmake
index e6b70a2..049304f 100644
--- a/cmake/config.cmake
+++ b/cmake/config.cmake
@@ -18,6 +18,14 @@ set(USE_PMTU ${LINUX})
 set(USE_PKTINFO ${LINUX})
 set(USE_PACKET_MARK ${LINUX})
 
+
+if(ANDROID)
+  set(USE_USER FALSE)
+else(ANDROID)
+  set(USE_USER TRUE)
+endif(ANDROID)
+
+
 # OSX doesn't support poll on devices...
 set(USE_SELECT ${DARWIN})
 
@@ -36,9 +44,16 @@ set(ENABLE_LTO FALSE CACHE BOOL "Enable link-time optimization")
 
 if(LINUX AND NOT ANDROID)
   set(ENABLE_SYSTEMD TRUE CACHE BOOL "Enable systemd support")
+else(LINUX AND NOT ANDROID)
+  set(ENABLE_SYSTEMD FALSE)
 endif(LINUX AND NOT ANDROID)
 
-set(WITH_CMDLINE_USER TRUE CACHE BOOL "Include support for setting user/group related options on the command line")
+if(USE_USER)
+  set(WITH_CMDLINE_USER TRUE CACHE BOOL "Include support for setting user/group related options on the command line")
+else(USE_USER)
+  set(WITH_CMDLINE_USER FALSE)
+endif(USE_USER)
+
 set(WITH_CMDLINE_LOGGING TRUE CACHE BOOL "Include support for setting logging related options on the command line")
 set(WITH_CMDLINE_OPERATION TRUE CACHE BOOL "Include support for setting options related to the VPN operation (like mode, interface, encryption method) on the command line")
 set(WITH_CMDLINE_COMMANDS TRUE CACHE BOOL "Include support for setting handler scripts (e.g. --on-up) on the command line")
diff --git a/src/config.c b/src/config.c
index 86e7df6..d0d1d52 100644
--- a/src/config.c
+++ b/src/config.c
@@ -383,14 +383,10 @@ bool fastd_config_read(const char *filename, fastd_peer_group_t *peer_group, fas
 
 /** Loads information about the configured user and group */
 static void configure_user(void) {
+#ifdef USE_USER
 	conf.uid = getuid();
 	conf.gid = getgid();
 
-#ifdef __ANDROID__
-	if (conf.user || conf.group) {
-		exit_error("config error: setting user/group is not supported on Android");
-	}
-#else
 	if (conf.user) {
 		struct passwd pwd, *pwdr;
 		size_t bufspace = 1024;
@@ -683,9 +679,12 @@ void fastd_config_release(void) {
 	free(conf.status_socket);
 #endif
 
+#ifdef USE_USER
 	free(conf.user);
 	free(conf.group);
 	free(conf.groups);
+#endif
+
 	free(conf.ifname);
 	free(conf.secret);
 	free(conf.protocol_config);
diff --git a/src/config.y b/src/config.y
index c998a41..404ac1d 100644
--- a/src/config.y
+++ b/src/config.y
@@ -213,13 +213,23 @@ peer_group_statement:
 	;
 
 user:		TOK_STRING {
+#ifdef USE_USER
 			free(conf.user);
 			conf.user = fastd_strdup($1->str);
+#else
+			fastd_config_error(&@$, state, "user setting is not supported on this platform");
+			YYERROR;
+#endif
 		}
 
 group:		TOK_STRING {
+#ifdef USE_USER
 			free(conf.group);
 			conf.group = fastd_strdup($1->str);
+#else
+			fastd_config_error(&@$, state, "group setting is not supported on this platform");
+			YYERROR;
+#endif
 		}
 
 drop_capabilities:
diff --git a/src/fastd.c b/src/fastd.c
index 5a71b6a..f05b43e 100644
--- a/src/fastd.c
+++ b/src/fastd.c
@@ -256,6 +256,8 @@ static inline void write_pid(void) {
 		return;
 	}
 #endif
+
+#ifdef USE_USER
 	uid_t uid = geteuid();
 	gid_t gid = getegid();
 
@@ -265,28 +267,32 @@ static inline void write_pid(void) {
 		if (seteuid(conf.uid) < 0)
 			pr_debug_errno("seteuid");
 	}
+#endif
 
 	FILE *f = fopen(conf.pid_file, "w");
-	if (f == NULL) {
-		pr_error_errno("can't write PID file: fopen");
-		goto end;
-	}
+	if (f) {
+		if (fprintf(f, "%u", (unsigned)getpid()) < 0)
+			pr_error_errno("can't write PID file: fprintf");
 
-	if (fprintf(f, "%u", (unsigned)getpid()) < 0)
-		pr_error_errno("can't write PID file: fprintf");
+		if (fclose(f) < 0)
+			pr_warn_errno("fclose");
 
-	if (fclose(f) < 0)
-		pr_warn_errno("fclose");
+	}
+	else {
+		pr_error_errno("can't write PID file: fopen");
+	}
 
- end:
+#ifdef USE_USER
 	if (seteuid(uid) < 0)
 		pr_debug_errno("seteuid");
 	if (setegid(gid) < 0)
 		pr_debug_errno("setegid");
+#endif
 }
 
 /** Switches to the configured user */
 static void set_user(void) {
+#ifdef USE_USER
 	if (conf.user || conf.group) {
 		if (setgid(conf.gid) < 0)
 			exit_errno("setgid");
@@ -296,10 +302,12 @@ static void set_user(void) {
 
 		pr_info("changed to UID %i, GID %i", (int)conf.uid, (int)conf.gid);
 	}
+#endif
 }
 
 /** Sets the configured user's supplementary groups */
 static void set_groups(void) {
+#ifdef USE_USER
 	if (conf.groups) {
 		if (setgroups(conf.n_groups, conf.groups) < 0) {
 			if (errno != EPERM)
@@ -312,6 +320,7 @@ static void set_groups(void) {
 				pr_debug_errno("setgroups");
 		}
 	}
+#endif
 }
 
 /** Switches the user and drops all capabilities */
diff --git a/src/fastd.h b/src/fastd.h
index fc4acd1..f46e221 100644
--- a/src/fastd.h
+++ b/src/fastd.h
@@ -204,6 +204,7 @@ struct fastd_config {
 
 	fastd_drop_caps_t drop_caps;		/**< Specifies if and when to drop capabilities */
 
+#ifdef USE_USER
 	char *user;				/**< Specifies which user to switch to after initialization */
 	char *group;				/**< Can specify an alternative group to switch to */
 
@@ -211,6 +212,7 @@ struct fastd_config {
 	gid_t gid;				/**< The GID of the configured group */
 	size_t n_groups;			/**< The number of supplementary groups of the user */
 	gid_t *groups;				/**< The supplementary groups of the configured user */
+#endif
 
 	const fastd_protocol_t *protocol;	/**< The handshake protocol */
 	fastd_string_stack_t *method_list;	/**< The list of configured method names */
diff --git a/src/fastd_config.h.in b/src/fastd_config.h.in
index 5286992..03ccc56 100644
--- a/src/fastd_config.h.in
+++ b/src/fastd_config.h.in
@@ -71,6 +71,9 @@
 /** Defined if the platform supports SO_MARK */
 #cmakedefine USE_PACKET_MARK
 
+/** Defined if the platform supports settings users and groups */
+#cmakedefine USE_USER
+
 /** Defined if the platform supports binding on IPv4 and IPv6 with a single socket */
 #cmakedefine USE_MULTIAF_BIND
 
diff --git a/src/status.c b/src/status.c
index 7505ef9..3c82e0c 100644
--- a/src/status.c
+++ b/src/status.c
@@ -203,6 +203,7 @@ void fastd_status_init(void) {
 		return;
 	}
 
+#ifdef USE_USER
 	uid_t uid = geteuid();
 	gid_t gid = getegid();
 
@@ -212,7 +213,7 @@ void fastd_status_init(void) {
 		if (seteuid(conf.uid) < 0)
 			pr_debug_errno("seteuid");
 	}
-
+#endif
 
 	ctx.status_fd = socket(AF_UNIX, SOCK_STREAM, 0);
 	if (ctx.status_fd < 0)
@@ -242,10 +243,12 @@ void fastd_status_init(void) {
 		exit_errno("fastd_status_init: listen");
 
 
+#ifdef USE_USER
 	if (seteuid(uid) < 0)
 		pr_debug_errno("seteuid");
 	if (setegid(gid) < 0)
 		pr_debug_errno("setegid");
+#endif
 }
 
 /** Closes the status socket */