Filter environment variables

Save all environment variables for later use in the application, clear
environment and re-apply only whitelisted variables for the main
firejail process. The whitelisted environment is only used by C
library. Sandboxed tools will get further variables used
internally (FIREJAIL_*).

All variables will be reapplied for the firejailed application.

This also lifts the length restriction for environment variables,
except for the variables used by Firejail itself or the sandboxed
tools.

1 files changed, 11 insertions, 19 deletions

diff --git a/src/firejail/dbus.c b/src/firejail/dbus.c
index 3cf75ed84..1d0f07089 100644
--- a/src/firejail/dbus.c
+++ b/src/firejail/dbus.c
@@ -329,7 +329,7 @@ void dbus_proxy_start(void) {
                         errExit("close");
 
                 if (arg_dbus_user == DBUS_POLICY_FILTER) {
-                        char *user_env = getenv(DBUS_SESSION_BUS_ADDRESS_ENV);
+                        const char *user_env = env_get(DBUS_SESSION_BUS_ADDRESS_ENV);
                         if (user_env == NULL) {
                                 char *dbus_user_socket = find_user_socket();
                                 write_arg(args_pipe[1], DBUS_SOCKET_PATH_PREFIX "%s",
@@ -350,7 +350,7 @@ void dbus_proxy_start(void) {
                 }
 
                 if (arg_dbus_system == DBUS_POLICY_FILTER) {
-                        char *system_env = getenv(DBUS_SYSTEM_BUS_ADDRESS_ENV);
+                        const char *system_env = env_get(DBUS_SYSTEM_BUS_ADDRESS_ENV);
                         if (system_env == NULL) {
                                 write_arg(args_pipe[1],
                                                   DBUS_SOCKET_PATH_PREFIX DBUS_SYSTEM_SOCKET);
@@ -435,8 +435,8 @@ static void socket_overlay(char *socket_path, char *proxy_path) {
         close(fd);
 }
 
-static char *get_socket_env(const char *name) {
-        char *value = getenv(name);
+static const char *get_socket_env(const char *name) {
+        const char *value = env_get(name);
         if (value == NULL)
                 return NULL;
         if (strncmp(value, DBUS_SOCKET_PATH_PREFIX,
@@ -446,21 +446,13 @@ static char *get_socket_env(const char *name) {
 }
 
 void dbus_set_session_bus_env(void) {
-        if (setenv(DBUS_SESSION_BUS_ADDRESS_ENV,
-                        DBUS_SOCKET_PATH_PREFIX RUN_DBUS_USER_SOCKET, 1) == -1) {
-                fprintf(stderr, "Error: cannot modify " DBUS_SESSION_BUS_ADDRESS_ENV
-                                                " required by --dbus-user\n");
-                exit(1);
-        }
+        env_store_name_val(DBUS_SESSION_BUS_ADDRESS_ENV,
+                           DBUS_SOCKET_PATH_PREFIX RUN_DBUS_USER_SOCKET, SETENV);
 }
 
 void dbus_set_system_bus_env(void) {
-        if (setenv(DBUS_SYSTEM_BUS_ADDRESS_ENV,
-                        DBUS_SOCKET_PATH_PREFIX RUN_DBUS_SYSTEM_SOCKET, 1) == -1) {
-                fprintf(stderr, "Error: cannot modify " DBUS_SYSTEM_BUS_ADDRESS_ENV
-                                                " required by --dbus-system\n");
-                exit(1);
-        }
+        env_store_name_val(DBUS_SYSTEM_BUS_ADDRESS_ENV,
+                           DBUS_SOCKET_PATH_PREFIX RUN_DBUS_SYSTEM_SOCKET, SETENV);
 }
 
 static void disable_socket_dir(void) {
@@ -506,7 +498,7 @@ void dbus_apply_policy(void) {
                         errExit("asprintf");
                 disable_file_or_dir(dbus_user_socket2);
 
-                char *user_env = get_socket_env(DBUS_SESSION_BUS_ADDRESS_ENV);
+                const char *user_env = get_socket_env(DBUS_SESSION_BUS_ADDRESS_ENV);
                 if (user_env != NULL && strcmp(user_env, dbus_user_socket) != 0 &&
                         strcmp(user_env, dbus_user_socket2) != 0)
                         disable_file_or_dir(user_env);
@@ -535,7 +527,7 @@ void dbus_apply_policy(void) {
 
                 disable_file_or_dir(DBUS_SYSTEM_SOCKET);
 
-                char *system_env = get_socket_env(DBUS_SYSTEM_BUS_ADDRESS_ENV);
+                const char *system_env = get_socket_env(DBUS_SYSTEM_BUS_ADDRESS_ENV);
                 if (system_env != NULL && strcmp(system_env, DBUS_SYSTEM_SOCKET) != 0)
                         disable_file_or_dir(system_env);
 
@@ -561,4 +553,4 @@ void dbus_apply_policy(void) {
 
         fwarning("An abstract unix socket for session D-BUS might still be available. Use --net or remove unix from --protocol set.\n");
 }
-#endif // HAVE_DBUSPROXY
\ No newline at end of file
+#endif // HAVE_DBUSPROXY