feat: allow to set defaut environment variables when opening a new session

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "dysm-rs"
-version = "0.1.0"
+version = "0.1.1"
 edition = "2021"
 authors = ["Dany LE"]
 description = "Diya Session Manager"

references/daemon.conf

@@ -7,6 +7,7 @@
 
 # PAM service
 # the pam service used for authentication
+# if not specified, default to diya
 pam_service = "diya"
 
 # Default session command
@@ -14,6 +15,7 @@ pam_service = "diya"
 # any session ruining. Often, this default session will be a login
 # session that handles the user input and send user
 # credentials to the daemon via Dbus message
+# this configuration is mandatory
 default_session_command = "/usr/bin/diyac -x /usr/bin/diya-login-shell"
 
 # default session user
@@ -23,12 +25,21 @@ default_session_user = "xdg"
 
 # if false keep only one session at a time
 # open a new session will close any previously opened session
-# default true, optional
+# default true (if not specified), optional
 enable_multiple_session = false
 
 # User session command
 # The command to run to start a user session after the
 # login session is successful
 # the logged in user will own this session
+# this configuration is mandatory
+user_session_command = "/usr/bin/diyac -x /usr/bin/diya-shell"
+
+# setting environment variables
+# when opening a session, optional
+[session.envars]
+# format key = string value
+# example
+DBUS_SESSION_BUS_ADDRESS = "unix:path=/tmp/dbus-1"
+DBUS_SESSION_BUS_PID = "3598"
 
-user_session_command = "/usr/bin/diyac -x /usr/bin/diya-shell"

src/auth.rs

@@ -35,6 +35,7 @@ use nix::unistd::execvpe;
 use nix::unistd::setgroups;
 use nix::unistd::User;
 use nix::unistd::{getgrouplist, initgroups, setgid, setuid};
+use std::collections::HashMap;
 use std::ffi::{CStr, CString};
 use std::os::raw::c_void;
 use std::ptr;
@@ -196,6 +197,7 @@ pub trait Session {
     ///
     /// - `&self` - Object that implement this trait
     /// - `command` (`&str`) - Command to executed in a new user session
+    /// - `envars` (`&HashMap<String, String>`) - environment variable for the new session
     ///
     /// # Returns
     ///
@@ -205,7 +207,11 @@ pub trait Session {
     ///
     /// Any error raised during session opening
     ///
-    fn run(&self, command: &str) -> Result<(), Box<dyn std::error::Error>>;
+    fn run(
+        &self,
+        command: &str,
+        envars: &HashMap<String, String>,
+    ) -> Result<(), Box<dyn std::error::Error>>;
 
     /// End the currently running session
     ///
@@ -234,6 +240,7 @@ trait DropPrivilege {
     ///
     /// - `&self` - Object that define this trait
     /// - `command` (`&str`) - Command that will be executed un the user session after privilege dropping
+    /// - `envars` (`&HashMap<String, String>`) - environment variable for the new session
     ///
     /// # Returns
     ///
@@ -242,7 +249,11 @@ trait DropPrivilege {
     /// # Errors
     /// Any error
     ///
-    fn drop_and_run(&self, command: &str) -> Result<(), Box<dyn std::error::Error>> {
+    fn drop_and_run(
+        &self,
+        command: &str,
+        envars: &HashMap<String, String>,
+    ) -> Result<(), Box<dyn std::error::Error>> {
         DEBUG!("Run command: {} as user: {}", command, self.username());
         let user =
             User::from_name(self.username())?.ok_or(ERR!("Unknown user {}", self.username()))?;
@@ -258,8 +269,12 @@ trait DropPrivilege {
         let arg_c = CString::new("-c")?;
         let arg_cmd = CString::new(command)?;
         let args = vec![arg0.as_c_str(), arg_c.as_c_str(), arg_cmd.as_c_str()];
-        let env_user = CString::new(format!("USER={}", self.username()))?;
-        let envs = vec![env_user.as_c_str()];
+
+        let mut envs_c_string = vec![CString::new(format!("USER={}", self.username()))?];
+        for (k, v) in envars {
+            envs_c_string.push(CString::new(format!("{}={}", k, v))?);
+        }
+        let envs: Vec<&CStr> = envs_c_string.iter().map(|e| e.as_c_str()).collect();
         execvpe(shell.as_c_str(), &args, &envs)?;
         Ok(())
     }
@@ -511,8 +526,12 @@ impl Session for AnonymousSession {
         Ok(())
     }
 
-    fn run(&self, command: &str) -> Result<(), Box<dyn std::error::Error>> {
-        self.drop_and_run(command)
+    fn run(
+        &self,
+        command: &str,
+        envars: &HashMap<String, String>,
+    ) -> Result<(), Box<dyn std::error::Error>> {
+        self.drop_and_run(command, envars)
     }
 
     fn end(&self) -> Result<(), Box<dyn std::error::Error>> {
@@ -535,10 +554,14 @@ impl Session for PamSession {
         Ok(())
     }
 
-    fn run(&self, command: &str) -> Result<(), Box<dyn std::error::Error>> {
+    fn run(
+        &self,
+        command: &str,
+        envars: &HashMap<String, String>,
+    ) -> Result<(), Box<dyn std::error::Error>> {
         self.pam_set_credentials(PAM_ESTABLISH_CRED)?
             .pam_open_session()?
-            .drop_and_run(command)
+            .drop_and_run(command, envars)
     }
 
     fn end(&self) -> Result<(), Box<dyn std::error::Error>> {

src/configuration.rs

@@ -8,7 +8,7 @@
 //! the `Display` trait for easy debugging and logging.
 use crate::INFO;
 use core::fmt;
-use std::path::PathBuf;
+use std::{collections::HashMap, path::PathBuf};
 use toml::Value;
 
 /// Configuration
@@ -25,6 +25,8 @@ pub struct Configuration {
     user_session_command: String,
     /// flag to enable multiple session
     enable_multiple_session: bool,
+    /// Session environment variables
+    session_envars: HashMap<String, String>,
 }
 
 impl Configuration {
@@ -77,6 +79,23 @@ impl Configuration {
                 .get("enable_multiple_session")
                 .and_then(Value::as_bool)
                 .unwrap_or(true),
+            session_envars: table
+                .get("session")
+                .and_then(Value::as_table)
+                .and_then(|table| table.get("envars"))
+                .and_then(Value::as_table)
+                .and_then(|table| {
+                    Some(
+                        table
+                            .into_iter()
+                            .filter_map(|(k, v)| {
+                                v.as_str()
+                                    .and_then(|value| Some((k.to_string(), value.to_string())))
+                            })
+                            .collect(),
+                    )
+                })
+                .unwrap_or(HashMap::new()),
         })
     }
 
@@ -120,6 +139,14 @@ impl Configuration {
     pub fn enable_multiple_session(&self) -> bool {
         self.enable_multiple_session
     }
+
+    /// Session default environment variables
+    ///
+    /// # Returs
+    /// HashMap<String, String>
+    pub fn session_envars(&self) -> &HashMap<String, String> {
+        &self.session_envars
+    }
 }
 
 impl fmt::Display for Configuration {
@@ -141,6 +168,10 @@ impl fmt::Display for Configuration {
             "  - Enable multiple session: {}",
             self.enable_multiple_session
         )?;
+        writeln!(f, "  - Session environment variables:")?;
+        for (k, v) in &self.session_envars {
+            writeln!(f, "    + {} = '{}'", k, v)?;
+        }
         Ok(())
     }
 }

src/session.rs

@@ -404,7 +404,7 @@ impl SessionManager {
             Ok(()) => {
                 DEBUG!("Authenticate success");
                 invocation.return_value(Some(&Variant::tuple_from_iter([true.to_variant()])));
-                if ! self.config.enable_multiple_session() {
+                if !self.config.enable_multiple_session() {
                     self.drop_all_sessions();
                 }
                 match self.open_session(self.config.user_session_command(), &session) {
@@ -445,7 +445,9 @@ impl SessionManager {
                 Ok(child)
             }
             ForkResult::Child => {
-                session.run(command).expect("This should not happend");
+                session
+                    .run(command, self.config.session_envars())
+                    .expect("This should not happend");
                 panic!();
             }
         }

src/tests.rs

@@ -20,4 +20,16 @@ fn test_configuration_loading() {
         "/usr/bin/diyac -x /usr/bin/diya-shell"
     );
     assert_eq!(config.enable_multiple_session(), false);
+
+    assert_eq!(
+        config
+            .session_envars()
+            .get("DBUS_SESSION_BUS_ADDRESS")
+            .unwrap(),
+        "unix:path=/tmp/dbus-1"
+    );
+    assert_eq!(
+        config.session_envars().get("DBUS_SESSION_BUS_PID").unwrap(),
+        "3598"
+    );
 }