Remove the `tedge` dependency on `UserManager`

The UserManager was used to run the `tedge` command as the `tedge` user
becomming `root` or `mosquitto` only when required.
In practice, this introduced more issues than benefits.
Notably, this forces to have a `tedge` user to run the command.
While switching to a different user is required only to create a
certificate under mosquitto.

The behavior is unchanged. Particularly, errors are ignored when giving
ownership of the certificate to mosquitto
(for instance, if the `tedge cert create` command is not run with `sudo`).

Signed-off-by: Didier Wenzek <didier.wenzek@free.fr>

14 files changed, 30 insertions, 93 deletions

diff --git a/crates/core/tedge/Cargo.toml b/crates/core/tedge/Cargo.toml
index 6c65ac3c..b169f4da 100644
--- a/crates/core/tedge/Cargo.toml
+++ b/crates/core/tedge/Cargo.toml
@@ -27,7 +27,6 @@ rustls_0_19 = {package = "rustls", version = "0.19.0" }
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 tedge_config = { path = "../../common/tedge_config" }
-tedge_users = { path = "../../common/tedge_users" }
 tedge_utils = { path = "../../common/tedge_utils" }
 thiserror = "1.0"
 toml = "0.5"
diff --git a/crates/core/tedge/src/cli/certificate/cli.rs b/crates/core/tedge/src/cli/certificate/cli.rs
index a3e9db64..dcc286cd 100644
--- a/crates/core/tedge/src/cli/certificate/cli.rs
+++ b/crates/core/tedge/src/cli/certificate/cli.rs
@@ -35,7 +35,6 @@ impl BuildCommand for TEdgeCertCli {
                     id,
                     cert_path: config.query(DeviceCertPathSetting)?,
                     key_path: config.query(DeviceKeyPathSetting)?,
-                    user_manager: context.user_manager,
                 };
                 cmd.into_boxed()
             }
@@ -51,7 +50,6 @@ impl BuildCommand for TEdgeCertCli {
                 let cmd = RemoveCertCmd {
                     cert_path: config.query(DeviceCertPathSetting)?,
                     key_path: config.query(DeviceKeyPathSetting)?,
-                    user_manager: context.user_manager,
                 };
                 cmd.into_boxed()
             }
diff --git a/crates/core/tedge/src/cli/certificate/create.rs b/crates/core/tedge/src/cli/certificate/create.rs
index 560c2a8f..2d1589c9 100644
--- a/crates/core/tedge/src/cli/certificate/create.rs
+++ b/crates/core/tedge/src/cli/certificate/create.rs
@@ -7,7 +7,6 @@ use std::{
     path::Path,
 };
 use tedge_config::*;
-use tedge_users::UserManager;
 use tedge_utils::paths::{set_permission, validate_parent_dir_exists};
 
 /// Create a self-signed device certificate
@@ -20,9 +19,6 @@ pub struct CreateCertCmd {
 
     /// The path where the device private key will be stored
     pub key_path: FilePath,
-
-    /// The UserManager required to change effective user id
-    pub user_manager: UserManager,
 }
 
 impl Command for CreateCertCmd {
@@ -39,17 +35,16 @@ impl Command for CreateCertCmd {
 
 impl CreateCertCmd {
     fn create_test_certificate(&self, config: &NewCertificateConfig) -> Result<(), CertError> {
-        let _user_guard = self.user_manager.become_user(tedge_users::BROKER_USER)?;
-
         validate_parent_dir_exists(&self.cert_path).map_err(CertError::CertPathError)?;
         validate_parent_dir_exists(&self.key_path).map_err(CertError::KeyPathError)?;
 
         let cert = KeyCertPair::new_selfsigned_certificate(config, &self.id)?;
 
-        // Creating files with permission 644
-        let mut cert_file = create_new_file(&self.cert_path)
-            .map_err(|err| err.cert_context(self.cert_path.clone()))?;
-        let mut key_file = create_new_file(&self.key_path)
+        // Creating files with permission 644 owned by the MQTT broker
+        let mut cert_file =
+            create_new_file(&self.cert_path, crate::BROKER_USER, crate::BROKER_GROUP)
+                .map_err(|err| err.cert_context(self.cert_path.clone()))?;
+        let mut key_file = create_new_file(&self.key_path, crate::BROKER_USER, crate::BROKER_GROUP)
             .map_err(|err| err.key_context(self.key_path.clone()))?;
 
         let cert_pem = cert.certificate_pem_string()?;
@@ -76,8 +71,18 @@ impl CreateCertCmd {
     }
 }
 
-fn create_new_file(path: impl AsRef<Path>) -> Result<File, CertError> {
-    Ok(OpenOptions::new().write(true).create_new(true).open(path)?)
+fn create_new_file(path: impl AsRef<Path>, user: &str, group: &str) -> Result<File, CertError> {
+    let file = OpenOptions::new()
+        .write(true)
+        .create_new(true)
+        .open(path.as_ref())?;
+
+    // Ignore errors - This was the behavior with the now deprecated user manager.
+    // - When `tedge cert create` is not run as root, a certificate is created but owned by the user running the command.
+    // - A better approach could be to remove this `chown` and run the command as mosquitto.
+    let _ = tedge_utils::file::change_user_and_group(path.as_ref(), user, group);
+
+    Ok(file)
 }
 
 #[cfg(test)]
@@ -85,7 +90,6 @@ mod tests {
     use super::*;
     use assert_matches::assert_matches;
     use std::fs;
-    use tedge_users::UserManager;
     use tempfile::*;
 
     #[test]
@@ -99,7 +103,6 @@ mod tests {
             id: String::from(id),
             cert_path: cert_path.clone(),
             key_path: key_path.clone(),
-            user_manager: UserManager::new(),
         };
 
         assert_matches!(
@@ -127,7 +130,6 @@ mod tests {
             id: "my-device-id".into(),
             cert_path: cert_path.clone(),
             key_path: key_path.clone(),
-            user_manager: UserManager::new(),
         };
 
         assert!(cmd
@@ -149,7 +151,6 @@ mod tests {
             id: "my-device-id".into(),
             cert_path,
             key_path,
-            user_manager: UserManager::new(),
         };
 
         let cert_error = cmd
@@ -168,7 +169,6 @@ mod tests {
             id: "my-device-id".into(),
             cert_path,
             key_path,
-            user_manager: UserManager::new(),
         };
 
         let cert_error = cmd
diff --git a/crates/core/tedge/src/cli/certificate/error.rs b/crates/core/tedge/src/cli/certificate/error.rs
index 8fffc417..8193350d 100644
--- a/crates/core/tedge/src/cli/certificate/error.rs
+++ b/crates/core/tedge/src/cli/certificate/error.rs
@@ -2,7 +2,6 @@ use reqwest::StatusCode;
 use std::error::Error;
 use tedge_config::FilePath;
 use tedge_config::{ConfigSettingError, TEdgeConfigError};
-use tedge_users::UserSwitchError;
 use tedge_utils::paths::PathsError;
 
 #[derive(thiserror::Error, Debug)]
@@ -72,9 +71,6 @@ pub enum CertError {
     #[error(transparent)]
     UrlParseError(#[from] url::ParseError),
 
-    #[error(transparent)]
-    UserSwitchError(#[from] UserSwitchError),
-
     #[error("HTTP Connection Problem: {msg} \nHint: {hint}")]
     CertificateValidationFailure { hint: String, msg: String },
 
diff --git a/crates/core/tedge/src/cli/certificate/remove.rs b/crates/core/tedge/src/cli/certificate/remove.rs
index e46acfbf..8f978972 100644
--- a/crates/core/tedge/src/cli/certificate/remove.rs
+++ b/crates/core/tedge/src/cli/certificate/remove.rs
@@ -1,7 +1,6 @@
 use super::error::CertError;
 use crate::command::Command;
 use tedge_config::*;
-use tedge_users::UserManager;
 use tedge_utils::paths::ok_if_not_found;
 
 /// Remove the device certificate
@@ -11,9 +10,6 @@ pub struct RemoveCertCmd {
 
     /// The path of the private key to be removed
     pub key_path: FilePath,
-
-    /// The UserManager required to change effective user id.
-    pub user_manager: UserManager,
 }
 
 impl Command for RemoveCertCmd {
@@ -29,7 +25,6 @@ impl Command for RemoveCertCmd {
 
 impl RemoveCertCmd {
     fn remove_certificate(&self) -> Result<(), CertError> {
-        let _user_guard = self.user_manager.become_user(tedge_users::BROKER_USER)?;
         std::fs::remove_file(&self.cert_path).or_else(ok_if_not_found)?;
         std::fs::remove_file(&self.key_path).or_else(ok_if_not_found)?;
 
diff --git a/crates/core/tedge/src/cli/connect/c8y_direct_connection.rs b/crates/core/tedge/src/cli/connect/c8y_direct_connection.rs
index bba72e6a..89400667 100644
--- a/crates/core/tedge/src/cli/connect/c8y_direct_connection.rs
+++ b/crates/core/tedge/src/cli/connect/c8y_direct_connection.rs
@@ -13,11 +13,8 @@ use std::path::PathBuf;
 use std::{fs::File, io::BufReader};
 use tedge_config::FilePath;
 
-use tedge_users::UserManager;
-
 // Connect directly to the c8y cloud over mqtt and publish device create message.
 pub fn create_device_with_direct_connection(
-    user_manager: UserManager,
     bridge_config: &BridgeConfig,
     device_type: &str,
 ) -> Result<(), ConnectError> {
@@ -37,7 +34,7 @@ pub fn create_device_with_direct_connection(
         bridge_config.bridge_root_cert_path.clone(),
     )?;
 
-    let pvt_key = read_pvt_key(user_manager, bridge_config.bridge_keyfile.clone())?;
+    let pvt_key = read_pvt_key(bridge_config.bridge_keyfile.clone())?;
     let cert_chain = read_cert_chain(bridge_config.bridge_certfile.clone())?;
 
     let _ = client_config.set_single_client_cert(cert_chain, pvt_key);
@@ -139,12 +136,7 @@ fn add_root_cert(
     Ok(())
 }
 
-fn read_pvt_key(
-    user_manager: UserManager,
-    key_file: tedge_config::FilePath,
-) -> Result<rustls_0_19::PrivateKey, ConnectError> {
-    // Become BROKER_USER to read the private key
-    let _user_guard = user_manager.become_user(tedge_users::BROKER_USER)?;
+fn read_pvt_key(key_file: tedge_config::FilePath) -> Result<rustls_0_19::PrivateKey, ConnectError> {
     parse_pkcs8_key(key_file.clone()).or_else(|_| parse_rsa_key(key_file))
 }
 
@@ -213,7 +205,6 @@ mod tests {
 
     #[test]
     fn parse_supported_key() {
-        let user_manager = UserManager::new();
         let key = concat!(
             "-----BEGIN RSA PRIVATE KEY-----\n",
             "MC4CAQ\n",
@@ -221,14 +212,13 @@ mod tests {
         );
         let mut temp_file = NamedTempFile::new().unwrap();
         temp_file.write_all(key.as_bytes()).unwrap();
-        let parsed_key = read_pvt_key(user_manager, temp_file.path().into()).unwrap();
+        let parsed_key = read_pvt_key(temp_file.path().into()).unwrap();
         let expected_pvt_key = rustls_0_19::PrivateKey(vec![48, 46, 2, 1]);
         assert_eq!(parsed_key, expected_pvt_key);
     }
 
     #[test]
     fn parse_unsupported_key() {
-        let user_manager = UserManager::new();
         let key = concat!(
             "-----BEGIN DSA PRIVATE KEY-----\n",
             "MC4CAQ\n",
@@ -236,7 +226,7 @@ mod tests {
         );
         let mut temp_file = NamedTempFile::new().unwrap();
         temp_file.write_all(key.as_bytes()).unwrap();
-        let err = read_pvt_key(user_manager, temp_file.path().into()).unwrap_err();
+        let err = read_pvt_key(temp_file.path().into()).unwrap_err();
         assert!(matches!(err, ConnectError::UnknownPrivateKeyFormat));
     }
 }
diff --git a/crates/core/tedge/src/cli/connect/cli.rs b/crates/core/tedge/src/cli/connect/cli.rs
index 654af945..7253d1a7 100644
--- a/crates/core/tedge/src/cli/connect/cli.rs
+++ b/crates/core/tedge/src/cli/connect/cli.rs
@@ -32,11 +32,7 @@ impl BuildCommand for TEdgeConnectOpt {
                 cloud: Cloud::C8y,
                 common_mosquitto_config: CommonMosquittoConfig::default(),
                 is_test_connection,
-                service_manager: service_manager(
-                    context.user_manager.clone(),
-                    context.config_location.tedge_config_root_path,
-                )?,
-                user_manager: context.user_manager,
+                service_manager: service_manager(context.config_location.tedge_config_root_path)?,
             },
             TEdgeConnectOpt::Az { is_test_connection } => ConnectCommand {
                 config_location: context.config_location.clone(),
@@ -44,11 +40,7 @@ impl BuildCommand for TEdgeConnectOpt {
                 cloud: Cloud::Azure,
                 common_mosquitto_config: CommonMosquittoConfig::default(),
                 is_test_connection,
-                service_manager: service_manager(
-                    context.user_manager.clone(),
-                    context.config_location.tedge_config_root_path,
-                )?,
-                user_manager: context.user_manager,
+                service_manager: service_manager(context.config_location.tedge_config_root_path)?,
             },
         }
         .into_boxed())
diff --git a/crates/core/tedge/src/cli/connect/command.rs b/crates/core/tedge/src/cli/connect/command.rs
index 7da926d0..faed5fde 100644
--- a/crates/core/tedge/src/cli/connect/command.rs
+++ b/crates/core/tedge/src/cli/connect/command.rs
@@ -7,7 +7,6 @@ use std::path::{Path, PathBuf};
 use std::sync::Arc;
 use std::time::Duration;
 use tedge_config::*;
-use tedge_users::UserManager;
 use tedge_utils::paths::{create_directories, ok_if_not_found, DraftFile};
 use which::which;
 
@@ -26,7 +25,6 @@ pub struct ConnectCommand {
     pub common_mosquitto_config: CommonMosquittoConfig,
     pub is_test_connection: bool,
     pub service_manager: Arc<dyn SystemServiceManager>,
-    pub user_manager: UserManager,
 }
 
 pub enum DeviceStatus {
@@ -135,7 +133,6 @@ impl Command for ConnectCommand {
             &bridge_config,
             &updated_mosquitto_config,
             self.service_manager.as_ref(),
-            self.user_manager.clone(),
             &self.config_location,
             &device_type,
         )?;
@@ -389,7 +386,6 @@ fn new_bridge(
     bridge_config: &BridgeConfig,
     common_mosquitto_config: &CommonMosquittoConfig,
     service_manager: &dyn SystemServiceManager,
-    user_manager: UserManager,
     config_location: &TEdgeConfigLocation,
     device_type: &str,
 ) -> Result<(), ConnectError> {
@@ -414,7 +410,6 @@ fn new_bridge(
     if bridge_config.cloud_name.eq("c8y") {
         println!("Creating the device in Cumulocity cloud.\n");
         let () = c8y_direct_connection::create_device_with_direct_connection(
-            user_manager,
             bridge_config,
             device_type,
         )?;
diff --git a/crates/core/tedge/src/cli/connect/error.rs b/crates/core/tedge/src/cli/connect/error.rs
index 4dc9453e..07ddbfbc 100644
--- a/crates/core/tedge/src/cli/connect/error.rs
+++ b/crates/core/tedge/src/cli/connect/error.rs
@@ -1,5 +1,3 @@
-use tedge_users::UserSwitchError;
-
 #[derive(thiserror::Error, Debug)]
 pub enum ConnectError {
     #[error("Couldn't load certificate, provide valid certificate path in configuration. Use 'tedge config --set'")]
@@ -51,7 +49,4 @@ pub enum ConnectError {
 
     #[error("Could not parse certificate")]
     RumqttcCertificate,
-
-    #[error(transparent)]
-    UserSwitchError(#[from] UserSwitchError),
 }
diff --git a/crates/core/tedge/src/cli/disconnect/cli.rs b/crates/core/tedge/src/cli/disconnect/cli.rs
index e13a9250..3afb8c26 100644
--- a/crates/core/tedge/src/cli/disconnect/cli.rs
+++ b/crates/core/tedge/src/cli/disconnect/cli.rs
@@ -22,10 +22,7 @@ impl BuildCommand for TEdgeDisconnectBridgeCli {
                 cloud: Cloud::C8y,
                 use_mapper: true,
                 use_agent: true,
-                service_manager: service_manager(
-                    context.user_manager.clone(),
-                    context.config_location.tedge_config_root_path,
-                )?,
+                service_manager: service_manager(context.config_location.tedge_config_root_path)?,
             },
             TEdgeDisconnectBridgeCli::Az => DisconnectBridgeCommand {
                 config_location: context.config_location.clone(),
@@ -33,10 +30,7 @@ impl BuildCommand for TEdgeDisconnectBridgeCli {
                 cloud: Cloud::Azure,
                 use_mapper: true,
                 use_agent: false,
-                service_manager: service_manager(
-                    context.user_manager.clone(),
-                    context.config_location.tedge_config_root_path,
-                )?,
+                service_manager: service_manager(context.config_location.tedge_config_root_path)?,
             },
         };
         Ok(cmd.into_boxed())
diff --git a/crates/core/tedge/src/command.rs b/crates/core/tedge/src/command.rs
index 0ad255f5..759afa4f 100644
--- a/crates/core/tedge/src/command.rs
+++ b/crates/core/tedge/src/command.rs
@@ -1,5 +1,3 @@
-use tedge_users::UserManager;
-
 /// A trait to be implemented by all tedge sub-commands.
 ///
 /// A command encapsulates all the required parameters and provides an `execute()` method
@@ -150,5 +148,4 @@ pub trait BuildCommand {
 pub struct BuildContext {
     pub config_repository: tedge_config::TEdgeConfigRepository,
     pub config_location: tedge_config::TEdgeConfigLocation,
-    pub user_manager: UserManager,
 }
diff --git a/crates/core/tedge/src/main.rs b/crates/core/tedge/src/main.rs
index e4dc777e..ea5ccd9a 100644
--- a/crates/core/tedge/src/main.rs
+++ b/crates/core/tedge/src/main.rs
@@ -5,7 +5,6 @@ use std::path::Path;
 
 use anyhow::Context;
 use clap::Parser;
-use tedge_users::UserManager;
 mod cli;
 mod command;
 mod error;
@@ -16,6 +15,9 @@ type ConfigError = crate::error::TEdgeError;
 
 use command::{BuildCommand, BuildContext};
 
+const BROKER_USER: &str = "mosquitto";
+const BROKER_GROUP: &str = "mosquitto";
+
 fn main() -> anyhow::Result<()> {
     let opt = cli::Opt::parse();
 
@@ -24,15 +26,12 @@ fn main() -> anyhow::Result<()> {
         return Ok(());
     }
 
-    let user_manager = UserManager::new();
     let tedge_config_location = tedge_config::TEdgeConfigLocation::from_custom_root(opt.config_dir);
-    let _user_guard = user_manager.become_user(tedge_users::TEDGE_USER)?;
     let config_repository = tedge_config::TEdgeConfigRepository::new(tedge_config_location.clone());
 
     let build_context = BuildContext {
         config_repository,
         config_location: tedge_config_location,
-        user_manager,
     };
 
     if let Some(tedge_opt) = opt.tedge {
diff --git a/crates/core/tedge/src/system_services/manager.rs b/crates/core/tedge/src/system_services/manager.rs
index 7c39ea8c..83b4cd56 100644
--- a/crates/core/tedge/src/system_services/manager.rs
+++ b/crates/core/tedge/src/system_services/manager.rs
@@ -2,7 +2,6 @@ use crate::system_services::*;
 use std::fmt::Debug;
 use std::path::PathBuf;
 use std::sync::Arc;
-use tedge_users::UserManager;
 
 /// Abstraction over the system-provided facility that manages starting, stopping as well as other
 /// service-related management functions of system services.
@@ -43,11 +42,7 @@ pub trait SystemServiceManager: Debug {
 }
 
 pub fn service_manager(
-    user_manager: UserManager,
     config_root: PathBuf,
 ) -> Result<Arc<dyn SystemServiceManager>, SystemServiceError> {
-    Ok(Arc::new(GeneralServiceManager::try_new(
-        user_manager,
-        config_root,
-    )?))
+    Ok(Arc::new(GeneralServiceManager::try_new(config_root)?))
 }
diff --git a/crates/core/tedge/src/system_services/managers/general_manager.rs b/crates/core/tedge/src/system_services/managers/general_manager.rs
index fad556e3..dd5f3f8c 100644
--- a/crates/core/tedge/src/system_services/managers/general_manager.rs
+++ b/crates/core/tedge/src/system_services/managers/general_manager.rs
@@ -5,20 +5,15 @@ use crate::system_services::{
 use std::fmt;
 use std::path::PathBuf;
 use std::process::ExitStatus;
-use tedge_users::{UserManager, ROOT_USER};
 
 #[derive(Debug)]
 pub struct GeneralServiceManager {
-    user_manager: UserManager,
     init_config: InitConfig,
     config_path: String,
 }
 
 impl GeneralServiceManager {
-    pub fn try_new(
-        user_manager: UserManager,
-        config_root: PathBuf,
-    ) -> Result<Self, SystemServiceError> {
+    pub fn try_new(config_root: PathBuf) -> Result<Self, SystemServiceError> {
         let init_config = SystemConfig::try_new(config_root.clone())?.init;
         let config_path = config_root
             .join(SERVICE_CONFIG_FILE)
@@ -26,7 +21,6 @@ impl GeneralServiceManager {
             .unwrap_or(SERVICE_CONFIG_FILE)
             .to_string();
         Ok(Self {
-            user_manager,
             init_config,
             config_path,
         })
@@ -238,8 +232,6 @@ impl GeneralServiceManager {
         exec_command: ExecCommand,
         config_path: &str,
     ) -> Result<ServiceCommandExitStatus, SystemServiceError> {
-        let _root_guard = self.user_manager.become_user(ROOT_USER);
-
         exec_command
             .to_command()
             .status()