Add validity checks for `SwitchUser` method

Change-Id: I586044883648768d682c70757b521564ea57d17e

diff --git a/sessiond/src/fs_helpers.cpp b/sessiond/src/fs_helpers.cpp
index 0fcf0f3..966f724 100644 (file)
--- a/sessiond/src/fs_helpers.cpp
+++ b/sessiond/src/fs_helpers.cpp
@@ -164,6 +164,20 @@ void fs_helpers::create_main_subdirectory(const int session_uid, std::string_vie
                        + "` subdirectory");
 }
 
+bool fs_helpers::subsession_exists(const int session_uid, const int subsession_id) try {
+       std::string home_dir = fs_helpers::get_home_dir_by_user_id(session_uid);
+       std::string main_dir = std::move(home_dir) + "/" + main_dir_name.data();
+       std::string subsession_dir = std::move(main_dir) + "/" + std::to_string(subsession_id);
+       fs::path subsession_path { subsession_dir };
+       return fs::exists(subsession_path);
+}
+catch (std::exception const &ex) {
+       std::cerr << "Exception " << ex.what() << std::endl
+               << "while executing subsession_exists function [session_uid=" << session_uid
+               << " subsession_id=" << subsession_id << "]" << std::endl;
+       return false;
+}
+
 void fs_helpers::add_user_subsession(const int session_uid, const int subsession_id)
 {
        try {

diff --git a/sessiond/src/fs_helpers.h b/sessiond/src/fs_helpers.h
index 8b61be5..333740c 100644 (file)
--- a/sessiond/src/fs_helpers.h
+++ b/sessiond/src/fs_helpers.h
@@ -18,6 +18,7 @@ namespace fs_helpers
        void copy_ownership(std::string_view src_path, std::string_view dest_path);
        std::string get_smack_label(std::string_view src_path, smack_label_type type);
        void copy_smack_attributes(std::string_view src_path, std::string_view dest_path);
+       bool subsession_exists(const int session_uid, const int subsession_id);
        void add_user_subsession(const int session_uid, const int subsession_id);
        void remove_user_subsession(const int session_uid, const int subsession_id);
        std::vector<int> get_user_list(const int session_uid);

diff --git a/sessiond/src/main.cpp b/sessiond/src/main.cpp
index c5b8c6e..0c0d76c 100644 (file)
--- a/sessiond/src/main.cpp
+++ b/sessiond/src/main.cpp
@@ -175,6 +175,11 @@ struct sessiond_context {
                        return;
                }
 
+               if (!fs_helpers::subsession_exists(session_uid, next_subsession_id)) {
+                       g_dbus_method_invocation_return_dbus_error(invocation, "org.freedesktop.DBus.Error.FileNotFound", "Invalid UID or subsession passed");
+                       return;
+               }
+
                switch_id += 1;
 
                int prev_subsession_id = INITIAL_SUB_SESSION_ID;