Fix broken realmfs autoresize

When a realm has enabled 'use-flatpak' a .desktop file for GNOME
Software will be automatically generated while that realm is running.

This .desktop file will launch GNOME Software from Citadel inside a
bubblewrap sandbox. The sandbox has been prepared so that GNOME
Software will install flatpak applications into a directory that belongs
to the realm associated with the .desktop file.

When a realm has enabled 'use-flatpak' this directory will be bind
mounted (read-only) into the root filesystem of the realm so that
applications installed by GNOME Software are visible and can be launched.

Cargo.toml

@@ -1,5 +1,5 @@
 [workspace]
-members = ["citadel-realms", "citadel-installer-ui", "citadel-tool", "realmsd", "realm-config-ui" ]
+members = ["citadel-realms", "citadel-installer-ui", "citadel-tool", "realmsd", "realm-config-ui", "launch-gnome-software" ]
 [profile.release]
 lto = true
 codegen-units = 1

citadel-tool/Cargo.toml

@@ -8,14 +8,14 @@ homepage = "https://subgraph.com"
 
 [dependencies]
 libcitadel = { path = "../libcitadel" }
-rpassword = "4.0"
+rpassword = "7.3"
-clap = "2.33"
+clap = { version = "4.5", features = ["cargo", "derive"] }
 lazy_static = "1.4"
 serde_derive = "1.0"
 serde = "1.0"
-toml = "0.5"
+toml = "0.8"
 hex = "0.4"
 byteorder = "1"
 dbus = "0.8.4"
-pwhash = "0.3.1"
+pwhash = "1.0"
 tempfile = "3"

citadel-tool/src/image/mod.rs

@@ -1,89 +1,97 @@
 use std::path::Path;
 use std::process::exit;
-
+use clap::{Arg,ArgMatches};
-use clap::{App,Arg,SubCommand,ArgMatches};
+use clap::{command, ArgAction, Command};
-use clap::AppSettings::*;
-use libcitadel::{Result, ResourceImage, Logger, LogLevel, Partition, KeyPair, ImageHeader, util};
 use hex;
 
-pub fn main(args: Vec<String>) {
+use libcitadel::{Result, ResourceImage, Logger, LogLevel, Partition, KeyPair, ImageHeader, util};
 
-    let app = App::new("citadel-image")
+pub fn main() {
+    let matches = command!()
         .about("Citadel update image builder")
-        .settings(&[ArgRequiredElseHelp,ColoredHelp, DisableHelpSubcommand, DisableVersion, DeriveDisplayOrder])
+        .arg_required_else_help(true)
+        .disable_help_subcommand(true)
+        .subcommand(
+            Command::new("metainfo")
+                .about("Display metainfo variables for an image file")
+                .arg(Arg::new("path").required(true).help("Path to image file")),
+        )
+        .subcommand(
+            Command::new("info")
+                .about("Display metainfo variables for an image file")
+                .arg(Arg::new("path").required(true).help("Path to image file")),
+        )
+        .subcommand(
+            Command::new("generate-verity")
+                .about("Generate dm-verity hash tree for an image file")
+                .arg(Arg::new("path").required(true).help("Path to image file")),
+        )
+        .subcommand(
+            Command::new("verify")
+                .about("Verify dm-verity hash tree for an image file")
+                .arg(
+                    Arg::new("option")
+                        .long("option")
+                        .required(true)
+                        .help("Path to image file"),
+                ),
+        )
+        .subcommand(
+            Command::new("install-rootfs")
+                .about("Install rootfs image file to a partition")
+                .arg(
+                    Arg::new("choose")
+                        .long("just-choose")
+                        .action(ArgAction::SetTrue)
+                        .help("Don't install anything, just show which partition would be chosen"),
+                )
+                .arg(
+                    Arg::new("skip-sha")
+                        .long("skip-sha")
+                        .action(ArgAction::SetTrue)
+                        .help("Skip verification of header sha256 value"),
+                )
+                .arg(
+                    Arg::new("no-prefer")
+                        .long("no-prefer")
+                        .action(ArgAction::SetTrue)
+                        .help("Don't set PREFER_BOOT flag"),
+                )
+                .arg(
+                    Arg::new("path")
+                        .required_unless_present("choose")
+                        .help("Path to image file"),
+                ),
+        )
+        .subcommand(Command::new("genkeys").about("Generate a pair of keys"))
+        .subcommand(
+            Command::new("decompress")
+                .about("Decompress a compressed image file")
+                .arg(Arg::new("path").required(true).help("Path to image file")),
+        )
+        .subcommand(
+            Command::new("bless")
+                .about("Mark currently mounted rootfs partition as successfully booted"),
+        )
+        .subcommand(
+            Command::new("verify-shasum")
+                .about("Verify the sha256 sum of the image")
+                .arg(Arg::new("path").required(true).help("Path to image file")),
+        )
+        .get_matches();
 
-        .subcommand(SubCommand::with_name("metainfo")
-            .about("Display metainfo variables for an image file")
-            .arg(Arg::with_name("path")
-                .required(true)
-                .help("Path to image file")))
-
-        .subcommand(SubCommand::with_name("info")
-            .about("Display metainfo variables for an image file")
-            .arg(Arg::with_name("path")
-                .required(true)
-                .help("Path to image file")))
-
-        .subcommand(SubCommand::with_name("generate-verity")
-            .about("Generate dm-verity hash tree for an image file")
-            .arg(Arg::with_name("path")
-                .required(true)
-                .help("Path to image file")))
-
-        .subcommand(SubCommand::with_name("verify")
-            .about("Verify dm-verity hash tree for an image file")
-            .arg(Arg::with_name("path")
-                .required(true)
-                .help("Path to image file")))
-
-        .subcommand(SubCommand::with_name("install-rootfs")
-            .about("Install rootfs image file to a partition")
-            .arg(Arg::with_name("choose")
-                .long("just-choose")
-                .help("Don't install anything, just show which partition would be chosen"))
-            .arg(Arg::with_name("skip-sha")
-                .long("skip-sha")
-                .help("Skip verification of header sha256 value"))
-            .arg(Arg::with_name("no-prefer")
-                .long("no-prefer")
-                .help("Don't set PREFER_BOOT flag"))
-            .arg(Arg::with_name("path")
-                .required_unless("choose")
-                .help("Path to image file")))
-
-        .subcommand(SubCommand::with_name("genkeys")
-            .about("Generate a pair of keys"))
-
-        .subcommand(SubCommand::with_name("decompress")
-            .about("Decompress a compressed image file")
-            .arg(Arg::with_name("path")
-                .required(true)
-                .help("Path to image file")))
-
-        .subcommand(SubCommand::with_name("bless")
-            .about("Mark currently mounted rootfs partition as successfully booted"))
-
-        .subcommand(SubCommand::with_name("verify-shasum")
-            .about("Verify the sha256 sum of the image")
-            .arg(Arg::with_name("path")
-                .required(true)
-                .help("Path to image file")));
-
-    Logger::set_log_level(LogLevel::Debug);
-
-    let matches = app.get_matches_from(args);
     let result = match matches.subcommand() {
-        ("metainfo", Some(m)) => metainfo(m),
+        Some(("metainfo", sub_m)) => metainfo(sub_m),
-        ("info", Some(m)) => info(m),
+        Some(("info", sub_m)) => info(sub_m),
-        ("generate-verity", Some(m)) => generate_verity(m),
+        Some(("generate-verity", sub_m)) => generate_verity(sub_m),
-        ("verify", Some(m)) => verify(m),
+        Some(("verify", sub_m)) => verify(sub_m),
-        ("sign-image", Some(m)) => sign_image(m),
+        Some(("sign-image", sub_m)) => sign_image(sub_m),
-        ("genkeys", Some(_)) => genkeys(),
+        Some(("genkeys", _)) => genkeys(),
-        ("decompress", Some(m)) => decompress(m),
+        Some(("decompress", sub_m)) => decompress(sub_m),
-        ("verify-shasum", Some(m)) => verify_shasum(m),
+        Some(("verify-shasum", sub_m)) => verify_shasum(sub_m),
-        ("install-rootfs", Some(m)) => install_rootfs(m),
+        Some(("install-rootfs", sub_m)) => install_rootfs(sub_m),
-        ("install", Some(m)) => install_image(m),
+        Some(("install", sub_m)) => install_image(sub_m),
-        ("bless", Some(_)) => bless(),
+        Some(("bless", _)) => bless(),
         _ => Ok(()),
     };
 
@@ -159,7 +167,9 @@ fn verify_shasum(arg_matches: &ArgMatches) -> Result<()> {
 }
 
 fn load_image(arg_matches: &ArgMatches) -> Result<ResourceImage> {
-    let path = arg_matches.value_of("path").expect("path argument missing");
+    let path = arg_matches.get_one::<String>("path")
+        .expect("path argument missing");
+
     if !Path::new(path).exists() {
         bail!("Cannot load image {}: File does not exist", path);
     }
@@ -171,14 +181,14 @@ fn load_image(arg_matches: &ArgMatches) -> Result<ResourceImage> {
 }
 
 fn install_rootfs(arg_matches: &ArgMatches) -> Result<()> {
-    if arg_matches.is_present("choose") {
+    if arg_matches.get_flag("choose") {
         let _ = choose_install_partition(true)?;
         return Ok(())
     }
 
     let img = load_image(arg_matches)?;
 
-    if !arg_matches.is_present("skip-sha") {
+    if !arg_matches.get_flag("skip-sha") {
         info!("Verifying sha256 hash of image");
         let shasum = img.generate_shasum()?;
         if shasum != img.metainfo().shasum() {
@@ -188,7 +198,7 @@ fn install_rootfs(arg_matches: &ArgMatches) -> Result<()> {
 
     let partition = choose_install_partition(true)?;
 
-    if !arg_matches.is_present("no-prefer") {
+    if !arg_matches.get_flag("no-prefer") {
         clear_prefer_boot()?;
         img.header().set_flag(ImageHeader::FLAG_PREFER_BOOT);
     }
@@ -212,7 +222,9 @@ fn sign_image(arg_matches: &ArgMatches) -> Result<()> {
 }
 
 fn install_image(arg_matches: &ArgMatches) -> Result<()> {
-    let source = arg_matches.value_of("path").expect("path argument missing");
+    let source = arg_matches.get_one::<String>("path")
+        .expect("path argument missing");
+
     let img = load_image(arg_matches)?;
     let _hdr = img.header();
     let metainfo = img.metainfo();

citadel-tool/src/install/cli.rs

@@ -125,7 +125,7 @@ fn read_passphrase(prompt: &str) -> io::Result<Option<String>> {
     loop {
         println!("{}", prompt);
         println!();
-        let passphrase = rpassword::read_password_from_tty(Some("  Passphrase : "))?;
+        let passphrase = rpassword::prompt_password("  Passphrase : ")?;
         if passphrase.is_empty() {
             println!("Passphrase cannot be empty");
             continue;
@@ -133,7 +133,7 @@ fn read_passphrase(prompt: &str) -> io::Result<Option<String>> {
         if passphrase == "q" || passphrase == "Q" {
             return Ok(None);
         }
-        let confirm    = rpassword::read_password_from_tty(Some("  Confirm    : "))?;
+        let confirm = rpassword::prompt_password("  Confirm    : ")?;
         if confirm == "q" || confirm == "Q" {
             return Ok(None);
         }

citadel-tool/src/main.rs

@@ -34,9 +34,9 @@ fn main() {
     } else if exe == Path::new("/usr/libexec/citadel-install-backend") {
         install_backend::main();
     } else if exe == Path::new("/usr/bin/citadel-image") {
-        image::main(args);
+        image::main();
     } else if exe == Path::new("/usr/bin/citadel-realmfs") {
-        realmfs::main(args);
+        realmfs::main();
     } else if exe == Path::new("/usr/bin/citadel-update") {
         update::main(args);
     } else if exe == Path::new("/usr/libexec/citadel-desktop-sync") {
@@ -57,8 +57,8 @@ fn dispatch_command(args: Vec<String>) {
         match command.as_str() {
             "boot" => boot::main(rebuild_args("citadel-boot", args)),
             "install" => install::main(rebuild_args("citadel-install", args)),
-            "image" => image::main(rebuild_args("citadel-image", args)),
+            "image" => image::main(),
-            "realmfs" => realmfs::main(rebuild_args("citadel-realmfs", args)),
+            "realmfs" => realmfs::main(),
             "update" => update::main(rebuild_args("citadel-update", args)),
             "mkimage" => mkimage::main(rebuild_args("citadel-mkimage", args)),
             "sync" => sync::main(rebuild_args("citadel-desktop-sync", args)),

citadel-tool/src/realmfs/mod.rs

@@ -1,28 +1,24 @@
-use clap::App;
+use clap::{command, Command};
-use clap::ArgMatches;
+use clap::{Arg, ArgMatches};
 
 use libcitadel::{Result,RealmFS,Logger,LogLevel};
 use libcitadel::util::is_euid_root;
-use clap::SubCommand;
-use clap::AppSettings::*;
-use clap::Arg;
 use libcitadel::ResizeSize;
 use std::process::exit;
 
-pub fn main(args: Vec<String>) {
+pub fn main() {
 
     Logger::set_log_level(LogLevel::Debug);
 
-    let app = App::new("citadel-realmfs")
+    let matches = command!()
-        .about("Citadel realmfs image tool")
+        .about("citadel-realmfs")
-        .settings(&[ArgRequiredElseHelp,ColoredHelp, DisableHelpSubcommand, DisableVersion, DeriveDisplayOrder,SubcommandsNegateReqs])
+        .arg_required_else_help(true)
-
+        .subcommand(Command::new("resize")
-        .subcommand(SubCommand::with_name("resize")
             .about("Resize an existing RealmFS image. If the image is currently sealed, it will also be unsealed.")
-            .arg(Arg::with_name("image")
+            .arg(Arg::new("image")
                 .help("Path or name of RealmFS image to resize")
                 .required(true))
-            .arg(Arg::with_name("size")
+            .arg(Arg::new("size")
                 .help("Size to increase RealmFS image to (or by if prefixed with '+')")
                 .long_help("\
 The size can be followed by a 'g' or 'm' character \
@@ -35,53 +31,53 @@ is the final absolute size of the image.")
                 .required(true)))
 
 
-        .subcommand(SubCommand::with_name("fork")
+        .subcommand(Command::new("fork")
             .about("Create a new RealmFS image as an unsealed copy of an existing image")
-            .arg(Arg::with_name("image")
+            .arg(Arg::new("image")
                 .help("Path or name of RealmFS image to fork")
                 .required(true))
 
-            .arg(Arg::with_name("forkname")
+            .arg(Arg::new("forkname")
                 .help("Name of new image to create")
                 .required(true)))
 
-        .subcommand(SubCommand::with_name("autoresize")
+        .subcommand(Command::new("autoresize")
             .about("Increase size of RealmFS image if not enough free space remains")
-            .arg(Arg::with_name("image")
+            .arg(Arg::new("image")
                 .help("Path or name of RealmFS image")
                 .required(true)))
 
-        .subcommand(SubCommand::with_name("update")
+        .subcommand(Command::new("update")
             .about("Open an update shell on the image")
-            .arg(Arg::with_name("image")
+            .arg(Arg::new("image")
                 .help("Path or name of RealmFS image")
                 .required(true)))
 
-        .subcommand(SubCommand::with_name("activate")
+        .subcommand(Command::new("activate")
             .about("Activate a RealmFS by creating a block device for the image and mounting it.")
-            .arg(Arg::with_name("image")
+            .arg(Arg::new("image")
                 .help("Path or name of RealmFS image to activate")
                 .required(true)))
 
-        .subcommand(SubCommand::with_name("deactivate")
+        .subcommand(Command::new("deactivate")
             .about("Deactivate a RealmFS by unmounting it and removing block device created during activation.")
-            .arg(Arg::with_name("image")
+            .arg(Arg::new("image")
                 .help("Path or name of RealmFS image to deactivate")
                 .required(true)))
 
 
-        .arg(Arg::with_name("image")
+        .arg(Arg::new("image")
             .help("Name of or path to RealmFS image to display information about")
-            .required(true));
+            .required(true))
+        .get_matches();
 
-    let matches = app.get_matches_from(args);
     let result = match matches.subcommand() {
-        ("resize", Some(m)) => resize(m),
+        Some(("resize", m)) => resize(m),
-        ("autoresize", Some(m)) => autoresize(m),
+        Some(("autoresize", m)) => autoresize(m),
-        ("fork", Some(m)) => fork(m),
+        Some(("fork", m)) => fork(m),
-        ("update", Some(m)) => update(m),
+        Some(("update", m)) => update(m),
-        ("activate", Some(m)) => activate(m),
+        Some(("activate", m)) => activate(m),
-        ("deactivate", Some(m)) => deactivate(m),
+        Some(("deactivate", m)) => deactivate(m),
         _ => image_info(&matches),
     };
 
@@ -92,7 +88,7 @@ is the final absolute size of the image.")
 }
 
 fn realmfs_image(arg_matches: &ArgMatches) -> Result<RealmFS> {
-    let image = match arg_matches.value_of("image") {
+    let image = match arg_matches.get_one::<String>("image") {
         Some(s) => s,
         None => bail!("Image argument required."),
     };
@@ -136,10 +132,9 @@ fn parse_resize_size(s: &str) -> Result<ResizeSize> {
 fn resize(arg_matches: &ArgMatches) -> Result<()> {
     let img = realmfs_image(arg_matches)?;
     info!("image is {}", img.path().display());
-    let size_arg = match arg_matches.value_of("size") {
+    let size_arg = match arg_matches.get_one::<String>("size") {
         Some(size) => size,
         None => "No size argument",
-
     };
     info!("Size is {}", size_arg);
     let mode_add = size_arg.starts_with('+');
@@ -165,7 +160,7 @@ fn autoresize(arg_matches: &ArgMatches) -> Result<()> {
 
 fn fork(arg_matches: &ArgMatches) -> Result<()> {
     let img = realmfs_image(arg_matches)?;
-    let forkname = match arg_matches.value_of("forkname") {
+    let forkname = match arg_matches.get_one::<String>("forkname") {
         Some(name) => name,
         None => bail!("No fork name argument"),
     };
@@ -190,7 +185,7 @@ fn update(arg_matches: &ArgMatches) -> Result<()> {
 
 fn activate(arg_matches: &ArgMatches) -> Result<()> {
     let img = realmfs_image(arg_matches)?;
-    let img_arg = arg_matches.value_of("image").unwrap();
+    let img_arg = arg_matches.get_one::<String>("image").unwrap();
 
     if img.is_activated() {
         info!("RealmFS image {} is already activated", img_arg);
@@ -203,7 +198,7 @@ fn activate(arg_matches: &ArgMatches) -> Result<()> {
 
 fn deactivate(arg_matches: &ArgMatches) -> Result<()> {
     let img = realmfs_image(arg_matches)?;
-    let img_arg = arg_matches.value_of("image").unwrap();
+    let img_arg = arg_matches.get_one::<String>("image").unwrap();
     if !img.is_activated() {
         info!("RealmFS image {} is not activated", img_arg);
     } else if img.is_in_use() {

citadel-tool/src/sync/desktop_sync.rs

@@ -99,7 +99,7 @@ impl DesktopFileSync {
     }
 
     fn collect_source_files(&mut self,  directory: impl AsRef<Path>) -> Result<()> {
-        let mut directory = Realms::current_realm_symlink().join(directory.as_ref());
+        let mut directory = self.realm.run_path().join(directory.as_ref());
         directory.push("share/applications");
         if directory.exists() {
             util::read_directory(&directory, |dent| {
@@ -126,7 +126,11 @@ impl DesktopFileSync {
     }
 
     fn remove_missing_target_files(&mut self) -> Result<()> {
-        let sources = self.source_filenames();
+        let mut sources = self.source_filenames();
+        // If flatpak is enabled, don't remove the generated GNOME Software desktop file
+        if self.realm.config().flatpak() {
+            sources.insert(format!("realm-{}.org.gnome.Software.desktop", self.realm.name()));
+        }
         let prefix = format!("realm-{}.", self.realm.name());
         util::read_directory(Self::CITADEL_APPLICATIONS, |dent| {
             if let Some(filename) = dent.file_name().to_str() {
@@ -182,7 +186,9 @@ impl DesktopFileSync {
 
     fn sync_item(&self, item: &DesktopItem) -> Result<()> {
         let mut dfp = DesktopFileParser::parse_from_path(&item.path, "/usr/libexec/citadel-run ")?;
-        if dfp.is_showable() {
+        // When use-flatpak is enabled a gnome-software desktop file will be generated
+        let flatpak_gs_hide = dfp.filename() == "org.gnome.Software.desktop" && self.realm.config().flatpak();
+        if dfp.is_showable() && !flatpak_gs_hide {
             self.sync_item_icon(&mut dfp);
             dfp.write_to_dir(Self::CITADEL_APPLICATIONS, Some(&self.realm))?;
         } else {

citadel-tool/src/sync/icons.rs

@@ -4,7 +4,6 @@ use std::path::{Path, PathBuf};
 
 use libcitadel::{Result, util, Realm};
 use std::cell::{RefCell, Cell};
-use std::fs;
 use crate::sync::desktop_file::DesktopFile;
 use crate::sync::REALM_BASE_PATHS;
 

citadel-tool/src/sync/mod.rs

@@ -14,7 +14,7 @@ fn has_arg(args: &[String], arg: &str) -> bool {
 
 pub const REALM_BASE_PATHS:&[&str]  = &[
     "rootfs/usr",
-    "rootfs/var/lib/flatpak/exports",
+    "flatpak/exports",
     "home/.local",
     "home/.local/share/flatpak/exports"
 ];

launch-gnome-software/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "launch-gnome-software"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+libcitadel = { path = "../libcitadel" }
+anyhow = "1.0"

launch-gnome-software/src/main.rs

@@ -0,0 +1,67 @@
+use std::env;
+
+use libcitadel::{Logger, LogLevel, Realm, Realms, util};
+use libcitadel::flatpak::GnomeSoftwareLauncher;
+
+use anyhow::{bail, Result};
+
+
+fn realm_arg() -> Option<String> {
+    let mut args = env::args();
+    while let Some(arg) = args.next() {
+        if arg == "--realm" {
+            return args.next();
+        }
+    }
+    None
+}
+
+fn choose_realm() -> Result<Realm> {
+    let mut realms = Realms::load()?;
+    if let Some(realm_name) = realm_arg() {
+        match realms.by_name(&realm_name) {
+            None => bail!("realm '{}' not found", realm_name),
+            Some(realm) => return Ok(realm),
+        }
+    }
+    let realm = match realms.current() {
+        Some(realm) => realm,
+        None => bail!("no current realm"),
+    };
+
+    Ok(realm)
+}
+
+fn has_arg(arg: &str) -> bool {
+    env::args()
+        .skip(1)
+        .any(|s| s == arg)
+}
+
+fn launch() -> Result<()> {
+    let realm = choose_realm()?;
+    if !util::is_euid_root() {
+        bail!("Must be run with root euid");
+    }
+    let mut launcher = GnomeSoftwareLauncher::new(realm)?;
+
+    if has_arg("--quit") {
+        launcher.quit()?;
+    } else {
+        if has_arg("--shell") {
+            launcher.set_run_shell();
+        }
+        launcher.launch()?;
+    }
+    Ok(())
+}
+
+fn main() {
+    if has_arg("--verbose") {
+        Logger::set_log_level(LogLevel::Verbose);
+    }
+
+    if let Err(err) = launch() {
+        eprintln!("Error: {}", err);
+    }
+}

libcitadel/Cargo.toml

@@ -10,6 +10,7 @@ nix = "0.17.0"
 toml = "0.5"
 serde = "1.0"
 serde_derive = "1.0"
+serde_json = "=1.0.1"
 lazy_static = "1.4"
 sodiumoxide = "0.2"
 hex = "0.4"

libcitadel/src/flatpak/bubblewrap.rs

@@ -0,0 +1,221 @@
+use std::ffi::OsStr;
+use std::{fs, io};
+use std::fs::File;
+use std::os::fd::AsRawFd;
+use std::os::unix::process::CommandExt;
+use std::path::Path;
+use std::process::Command;
+
+use crate::{Logger, LogLevel, Result, verbose};
+
+const BWRAP_PATH: &str = "/usr/libexec/flatpak-bwrap";
+
+pub struct BubbleWrap {
+    command: Command,
+}
+
+impl BubbleWrap {
+
+    pub fn new() -> Self {
+        BubbleWrap {
+            command: Command::new(BWRAP_PATH),
+        }
+    }
+
+    fn add_arg<S: AsRef<OsStr>>(&mut self, arg: S) -> &mut Self {
+        self.command.arg(arg);
+        self
+    }
+
+    fn add_args<S: AsRef<OsStr>>(&mut self, args: &[S]) -> &mut Self {
+        for arg in args {
+            self.add_arg(arg.as_ref());
+        }
+        self
+    }
+
+    pub fn ro_bind(&mut self, path_list: &[&str]) -> &mut Self {
+        for &path in path_list {
+            self.add_args(&["--ro-bind", path, path]);
+        }
+        self
+    }
+
+    pub fn ro_bind_to(&mut self, src: &str, dest: &str) -> &mut Self {
+        self.add_args(&["--ro-bind", src, dest])
+    }
+
+    pub fn bind_to(&mut self, src: &str, dest: &str) -> &mut Self {
+        self.add_args(&["--bind", src, dest])
+    }
+
+    pub fn create_dirs(&mut self, dir_list: &[&str]) -> &mut Self {
+        for &dir in dir_list {
+            self.add_args(&["--dir", dir]);
+        }
+        self
+    }
+
+    pub fn create_symlinks(&mut self, links: &[(&str, &str)]) -> &mut Self {
+        for (src,dest) in links {
+            self.add_args(&["--symlink", src, dest]);
+        }
+        self
+    }
+
+    pub fn mount_dev(&mut self) -> &mut Self {
+        self.add_args(&["--dev", "/dev"])
+    }
+
+    pub fn mount_proc(&mut self) -> &mut Self {
+        self.add_args(&["--proc", "/proc"])
+    }
+
+    pub fn dev_bind(&mut self, path: &str) -> &mut Self {
+        self.add_args(&["--dev-bind", path, path])
+    }
+
+    pub fn clear_env(&mut self) -> &mut Self {
+        self.add_arg("--clearenv")
+    }
+
+    pub fn set_env_list(&mut self, env_list: &[&str]) -> &mut Self {
+        for line in env_list {
+            if let Some((k,v)) = line.split_once("=") {
+                self.add_args(&["--setenv", k, v]);
+            } else {
+                eprintln!("Warning: environment variable '{}' does not have = delimiter. Ignoring", line);
+            }
+        }
+        self
+    }
+
+    pub fn unshare_all(&mut self) -> &mut Self {
+        self.add_arg("--unshare-all")
+    }
+
+    pub fn share_net(&mut self) -> &mut Self {
+        self.add_arg("--share-net")
+    }
+
+    pub fn log_command(&self) {
+        let mut buffer = String::new();
+        verbose!("{}", BWRAP_PATH);
+        for arg in self.command.get_args() {
+            if let Some(s) = arg.to_str() {
+                if s.starts_with("-") {
+                    if !buffer.is_empty() {
+                        verbose!("    {}", buffer);
+                        buffer.clear();
+                    }
+                }
+                if !buffer.is_empty() {
+                    buffer.push(' ');
+                }
+                buffer.push_str(s);
+            }
+        }
+        if !buffer.is_empty() {
+            verbose!("    {}", buffer);
+        }
+    }
+
+    pub fn status_file(&mut self, status_file: &File) -> &mut Self {
+        // Rust sets O_CLOEXEC when opening files so we create
+        // a new descriptor that will remain open across exec()
+        let dup_fd = unsafe {
+            libc::dup(status_file.as_raw_fd())
+        };
+        if dup_fd == -1 {
+            warn!("Failed to dup() status file descriptor: {}", io::Error::last_os_error());
+            warn!("Skipping --json-status-fd argument");
+            self
+        } else {
+            self.add_arg("--json-status-fd")
+                .add_arg(dup_fd.to_string())
+        }
+    }
+
+    pub fn launch<S: AsRef<OsStr>>(&mut self, cmd: &[S]) -> Result<()> {
+        if Logger::is_log_level(LogLevel::Verbose) {
+            self.log_command();
+            let s = cmd.iter().map(|s| format!("{} ", s.as_ref().to_str().unwrap())).collect::<String>();
+            verbose!("    {}", s)
+        }
+        self.add_args(cmd);
+        let err = self.command.exec();
+        bail!("failed to exec bubblewrap: {}", err);
+    }
+}
+
+#[derive(Deserialize,Clone)]
+#[serde(rename_all="kebab-case")]
+pub struct BubbleWrapRunningStatus {
+    pub child_pid: u64,
+    pub cgroup_namespace: u64,
+    pub ipc_namespace: u64,
+    pub mnt_namespace: u64,
+    pub pid_namespace: u64,
+    pub uts_namespace: u64,
+}
+
+#[derive(Deserialize,Clone)]
+#[serde(rename_all="kebab-case")]
+pub struct BubbleWrapExitStatus {
+    pub exit_code: u32,
+}
+
+#[derive(Clone)]
+pub struct BubbleWrapStatus {
+    running: BubbleWrapRunningStatus,
+    exit: Option<BubbleWrapExitStatus>,
+}
+
+impl BubbleWrapStatus {
+    pub fn parse_file(path: impl AsRef<Path>) -> Result<Option<Self>> {
+        if !path.as_ref().exists() {
+            return Ok(None)
+        }
+
+        let s = fs::read_to_string(path)
+            .map_err(context!("error reading status file"))?;
+
+        let mut lines = s.lines();
+        let running = match lines.next() {
+            None => return Ok(None),
+            Some(s) => serde_json::from_str::<BubbleWrapRunningStatus>(s)
+                .map_err(context!("failed to parse status line ({})", s))?
+        };
+
+        let exit = match lines.next() {
+            None => None,
+            Some(s) => Some(serde_json::from_str::<BubbleWrapExitStatus>(s)
+                .map_err(context!("failed to parse exit line ({})", s))?)
+        };
+
+        Ok(Some(BubbleWrapStatus {
+            running,
+            exit
+        }))
+    }
+
+    pub fn is_running(&self) -> bool {
+        self.exit.is_none()
+    }
+
+    pub fn running_status(&self) -> &BubbleWrapRunningStatus {
+        &self.running
+    }
+
+    pub fn child_pid(&self) -> u64 {
+        self.running.child_pid
+    }
+
+    pub fn pid_namespace(&self) -> u64 {
+        self.running.pid_namespace
+    }
+
+    pub fn exit_status(&self) -> Option<&BubbleWrapExitStatus> {
+        self.exit.as_ref()
+    }
+}

libcitadel/src/flatpak/launcher.rs

@@ -0,0 +1,259 @@
+use std::{fs, io};
+use std::fs::File;
+use std::os::unix::fs::FileTypeExt;
+use std::os::unix::prelude::CommandExt;
+use std::path::{Path, PathBuf};
+use std::process::Command;
+
+use crate::{Realm, Result, util};
+use crate::flatpak::{BubbleWrap, BubbleWrapStatus, SANDBOX_STATUS_FILE_DIRECTORY, SandboxStatus};
+use crate::flatpak::netns::NetNS;
+
+
+const FLATPAK_PATH: &str = "/usr/bin/flatpak";
+
+const ENVIRONMENT: &[&str; 7] = &[
+    "HOME=/home/citadel",
+    "USER=citadel",
+    "XDG_RUNTIME_DIR=/run/user/1000",
+    "XDG_DATA_DIRS=/home/citadel/.local/share/flatpak/exports/share:/usr/share",
+    "TERM=xterm-256color",
+    "GTK_A11Y=none",
+    "FLATPAK_USER_DIR=/home/citadel/realm-flatpak",
+];
+
+const FLATHUB_URL: &str = "https://dl.flathub.org/repo/flathub.flatpakrepo";
+
+pub struct GnomeSoftwareLauncher {
+    realm: Realm,
+    status: Option<BubbleWrapStatus>,
+    netns: NetNS,
+    run_shell: bool,
+}
+impl GnomeSoftwareLauncher {
+
+    pub fn new(realm: Realm) -> Result<Self> {
+        let sandbox_status = SandboxStatus::load(SANDBOX_STATUS_FILE_DIRECTORY)?;
+        let status = sandbox_status.realm_status(&realm);
+        let netns = NetNS::new(NetNS::GS_NETNS_NAME);
+        Ok(GnomeSoftwareLauncher {
+            realm,
+            status,
+            netns,
+            run_shell: false,
+        })
+    }
+
+    pub fn set_run_shell(&mut self) {
+        self.run_shell = true;
+    }
+
+    fn ensure_flatpak_dir(&self) -> Result<()> {
+        let flatpak_user_dir = self.realm.base_path_file("flatpak");
+        if !flatpak_user_dir.exists() {
+            if let Err(err) = fs::create_dir(&flatpak_user_dir) {
+                bail!("failed to create realm flatpak directory ({}): {}", flatpak_user_dir.display(), err);
+            }
+            util::chown_user(&flatpak_user_dir)?;
+        }
+        Ok(())
+    }
+
+    fn add_flathub(&self) -> Result<()> {
+        let flatpak_user_dir = self.realm.base_path_file("flatpak");
+
+        match Command::new(FLATPAK_PATH)
+            .env("FLATPAK_USER_DIR", flatpak_user_dir)
+            .arg("remote-add")
+            .arg("--user")
+            .arg("--if-not-exists")
+            .arg("flathub")
+            .arg(FLATHUB_URL)
+            .status() {
+            Ok(status) => {
+                if status.success() {
+                    Ok(())
+
+                } else {
+                    bail!("failed to add flathub repo")
+                }
+            },
+            Err(err) =>  bail!("error running flatpak command: {}", err),
+        }
+    }
+
+    fn scan_tmp_directory(path: &Path) -> io::Result<Option<String>> {
+        for entry in fs::read_dir(&path)? {
+            let entry = entry?;
+            if entry.file_type()?.is_socket() {
+                if let Some(filename) = entry.path().file_name() {
+                    if let Some(filename) = filename.to_str() {
+                        if filename.starts_with("dbus-") {
+                            return Ok(Some(format!("/tmp/{}", filename)));
+                        }
+                    }
+                }
+            }
+        }
+        Ok(None)
+    }
+
+    fn find_dbus_socket(&self) -> Result<String> {
+        let pid = self.running_pid()?;
+        let tmp_dir = PathBuf::from(format!("/proc/{}/root/tmp", pid));
+        if !tmp_dir.is_dir() {
+            bail!("no /tmp directory found for process pid={}", pid);
+        }
+
+        if let Some(s) = Self::scan_tmp_directory(&tmp_dir)
+            .map_err(context!("error reading directory {}", tmp_dir.display()))? {
+            Ok(s)
+
+        } else {
+            bail!("no dbus socket found in /tmp directory for process pid={}", pid);
+        }
+    }
+
+    fn launch_sandbox(&self, status_file: &File) -> Result<()> {
+        self.ensure_flatpak_dir()?;
+        if let Err(err) = self.netns.nsenter() {
+            bail!("Failed to enter 'gnome-software' network namespace: {}", err);
+        }
+        verbose!("Entered network namespace ({})", NetNS::GS_NETNS_NAME);
+
+        if let Err(err) = util::drop_privileges(1000, 1000) {
+            bail!("Failed to drop privileges to uid = gid = 1000: {}", err);
+        }
+        verbose!("Dropped privileges (uid=1000, gid=1000)");
+
+        self.add_flathub()?;
+        let flatpak_user_dir = self.realm.base_path_file("flatpak");
+        let flatpak_user_dir = flatpak_user_dir.to_str().unwrap();
+
+        let cmd = if self.run_shell { "/usr/bin/bash" } else { "/usr/bin/gnome-software"};
+        verbose!("Running command in sandbox: {}", cmd);
+
+        BubbleWrap::new()
+            .ro_bind(&[
+                "/usr/bin",
+                "/usr/lib",
+                "/usr/libexec",
+                "/usr/share/dbus-1",
+                "/usr/share/icons",
+                "/usr/share/mime",
+                "/usr/share/X11",
+                "/usr/share/glib-2.0",
+                "/usr/share/xml",
+                "/usr/share/drirc.d",
+                "/usr/share/fontconfig",
+                "/usr/share/fonts",
+                "/usr/share/zoneinfo",
+                "/usr/share/swcatalog",
+
+                "/etc/passwd",
+                "/etc/machine-id",
+                "/etc/nsswitch.conf",
+                "/etc/fonts",
+                "/etc/ssl",
+                "/sys/dev/char", "/sys/devices",
+                "/run/user/1000/wayland-0",
+            ])
+            .ro_bind_to("/run/NetworkManager/resolv.conf", "/etc/resolv.conf")
+            .bind_to(flatpak_user_dir, "/home/citadel/realm-flatpak")
+            .create_symlinks(&[
+                ("usr/lib", "/lib64"),
+                ("usr/bin", "/bin"),
+                ("/tmp", "/var/tmp"),
+            ])
+            .create_dirs(&[
+                "/var/lib/flatpak",
+                "/home/citadel",
+                "/tmp",
+                "/sys/block", "/sys/bus", "/sys/class",
+            ])
+
+
+            .mount_dev()
+            .dev_bind("/dev/dri")
+            .mount_proc()
+            .unshare_all()
+            .share_net()
+
+            .clear_env()
+            .set_env_list(ENVIRONMENT)
+
+            .status_file(status_file)
+
+            .launch(&["dbus-run-session", "--", cmd])?;
+        Ok(())
+    }
+
+    pub fn new_realm_status_file(&self) -> Result<File> {
+        let path = Path::new(SANDBOX_STATUS_FILE_DIRECTORY).join(self.realm.name());
+        File::create(&path)
+            .map_err(context!("failed to open sandbox status file {}", path.display()))
+    }
+
+    pub fn launch(&self) -> Result<()> {
+        self.netns.ensure_exists()?;
+        if self.is_running() {
+            let cmd = if self.run_shell { "/usr/bin/bash" } else { "/usr/bin/gnome-software"};
+            self.launch_in_running_sandbox(&[cmd])?;
+        } else {
+            let status_file = self.new_realm_status_file()?;
+            self.ensure_flatpak_dir()?;
+            self.launch_sandbox(&status_file)?;
+        }
+        Ok(())
+    }
+
+    pub fn quit(&self) -> Result<()> {
+        if self.is_running() {
+            self.launch_in_running_sandbox(&["/usr/bin/gnome-software", "--quit"])?;
+        } else {
+            warn!("No running sandbox found for realm {}", self.realm.name());
+        }
+        Ok(())
+    }
+
+    pub fn is_running(&self) -> bool {
+        self.status.as_ref()
+            .map(|s| s.is_running())
+            .unwrap_or(false)
+    }
+
+    fn running_pid(&self) -> Result<u64> {
+        self.status.as_ref()
+            .map(|s| s.child_pid())
+            .ok_or(format_err!("no sandbox status available for realm '{}',", self.realm.name()))
+    }
+
+    fn dbus_session_address(&self) -> Result<String> {
+        let dbus_socket = Self::find_dbus_socket(&self)?;
+        Ok(format!("unix:path={}", dbus_socket))
+    }
+
+    fn launch_in_running_sandbox(&self, command: &[&str]) -> Result<()> {
+        let dbus_address = self.dbus_session_address()?;
+
+        let pid = self.running_pid()?.to_string();
+        let mut env = ENVIRONMENT.iter()
+            .map(|s| s.split_once('=').unwrap())
+            .collect::<Vec<_>>();
+        env.push(("DBUS_SESSION_BUS_ADDRESS", dbus_address.as_str()));
+
+        let err = Command::new("/usr/bin/nsenter")
+            .env_clear()
+            .envs( env )
+            .args(&[
+                "--all",
+                "--target", pid.as_str(),
+                "--setuid", "1000",
+                "--setgid", "1000",
+            ])
+            .args(command)
+            .exec();
+
+        Err(format_err!("failed to execute nsenter: {}", err))
+    }
+}

libcitadel/src/flatpak/mod.rs

@@ -0,0 +1,16 @@
+
+pub(crate) mod setup;
+pub(crate) mod status;
+
+pub(crate) mod bubblewrap;
+
+pub(crate) mod launcher;
+
+pub(crate) mod netns;
+
+pub use status::SandboxStatus;
+
+pub use bubblewrap::{BubbleWrap,BubbleWrapStatus,BubbleWrapRunningStatus,BubbleWrapExitStatus};
+pub use launcher::GnomeSoftwareLauncher;
+
+pub const SANDBOX_STATUS_FILE_DIRECTORY: &str = "/run/citadel/realms/gs-sandbox-status";

libcitadel/src/flatpak/netns.rs

@@ -0,0 +1,132 @@
+use std::ffi::OsStr;
+use std::path::Path;
+use std::process::Command;
+
+use crate::{util,Result};
+
+
+const BRIDGE_NAME: &str = "vz-clear";
+const VETH0: &str = "gs-veth0";
+const VETH1: &str = "gs-veth1";
+const IP_ADDRESS: &str = "172.17.0.222/24";
+const GW_ADDRESS: &str = "172.17.0.1";
+
+
+pub struct NetNS {
+    name: String,
+}
+
+impl NetNS {
+    pub const GS_NETNS_NAME: &'static str = "gnome-software";
+    pub fn new(name: &str) -> Self {
+        NetNS {
+            name: name.to_string(),
+        }
+    }
+
+    fn create(&self) -> crate::Result<()> {
+        Ip::new().link_add_veth(VETH0, VETH1).run()?;
+        Ip::new().link_set_netns(VETH0, &self.name).run()?;
+        Ip::new().link_set_master(VETH1, BRIDGE_NAME).run()?;
+        Ip::new().link_set_dev_up(VETH1).run()?;
+
+        Ip::new().ip_netns_exec_ip(&self.name).addr_add(IP_ADDRESS, VETH0).run()?;
+        Ip::new().ip_netns_exec_ip(&self.name).link_set_dev_up(VETH0).run()?;
+        Ip::new().ip_netns_exec_ip(&self.name).route_add_default(GW_ADDRESS).run()?;
+
+        Ok(())
+    }
+    pub fn ensure_exists(&self) -> Result<()> {
+        if Path::new(&format!("/run/netns/{}", self.name)).exists() {
+            verbose!("Network namespace ({}) exists", self.name);
+            return Ok(())
+        }
+        verbose!("Setting up network namespace ({})", self.name);
+
+        Ip::new().netns_add(&self.name).run()
+            .map_err(context!("Failed to add network namespace '{}'", self.name))?;
+
+        if let Err(err) = self.create() {
+            Ip::new().netns_delete(&self.name).run()?;
+            Err(err)
+        } else {
+            Ok(())
+        }
+    }
+
+    pub fn nsenter(&self) -> Result<()> {
+        util::nsenter_netns(&self.name)
+    }
+}
+const IP_PATH: &str = "/usr/sbin/ip";
+struct Ip {
+    command: Command,
+}
+
+impl Ip {
+
+    fn new() -> Self {
+        let mut command = Command::new(IP_PATH);
+        command.env_clear();
+        Ip { command }
+    }
+
+    fn add_args<S: AsRef<OsStr>>(&mut self, args: &[S]) -> &mut Self {
+        for arg in args {
+            self.command.arg(arg);
+        }
+        self
+    }
+
+    pub fn netns_add(&mut self, name: &str) -> &mut Self {
+        self.add_args(&["netns", "add", name])
+    }
+
+    pub fn netns_delete(&mut self, name: &str) -> &mut Self {
+        self.add_args(&["netns", "delete", name])
+    }
+
+    pub fn link_add_veth(&mut self, name: &str, peer_name: &str) -> &mut Self {
+        self.add_args(&["link", "add", name, "type", "veth", "peer", "name", peer_name])
+    }
+
+    pub fn link_set_netns(&mut self, iface: &str, netns_name: &str) -> &mut Self {
+        self.add_args(&["link", "set", iface, "netns", netns_name])
+    }
+
+    pub fn link_set_master(&mut self, iface: &str, bridge_name: &str) -> &mut Self {
+        self.add_args(&["link", "set", iface, "master", bridge_name])
+    }
+
+    pub fn link_set_dev_up(&mut self, iface: &str) -> &mut Self {
+        self.add_args(&["link", "set", "dev", iface, "up"])
+    }
+
+    pub fn ip_netns_exec_ip(&mut self, netns_name: &str) -> &mut Self {
+        self.add_args(&["netns", "exec", netns_name, IP_PATH])
+    }
+
+    pub fn addr_add(&mut self, ip_address: &str, dev: &str) -> &mut Self {
+        self.add_args(&["addr", "add", ip_address, "dev", dev])
+    }
+
+    pub fn route_add_default(&mut self, gateway: &str) -> &mut Self {
+        self.add_args(&["route", "add", "default", "via", gateway])
+    }
+
+    fn run(&mut self) -> crate::Result<()> {
+        verbose!("{:?}", self.command);
+        match self.command.status() {
+            Ok(status) => {
+                if status.success() {
+                    Ok(())
+                } else {
+                    bail!("IP command ({:?}) did not succeeed.", self.command);
+                }
+            }
+            Err(err) => {
+                bail!("error running ip command ({:?}): {}", self.command, err);
+            }
+        }
+    }
+}

libcitadel/src/flatpak/setup.rs

@@ -0,0 +1,58 @@
+use std::path::Path;
+use crate::{Realm, Result, util};
+
+const GNOME_SOFTWARE_DESKTOP_TEMPLATE: &str = "\
+[Desktop Entry]
+Name=Software
+Comment=Add, remove or update software on this computer
+Icon=org.gnome.Software
+Exec=/usr/libexec/launch-gnome-software --realm $REALM_NAME
+Terminal=false
+Type=Application
+Categories=GNOME;GTK;System;PackageManager;
+Keywords=Updates;Upgrade;Sources;Repositories;Preferences;Install;Uninstall;Program;Software;App;Store;
+StartupNotify=true
+";
+
+const APPLICATION_DIRECTORY: &str = "/home/citadel/.local/share/applications";
+
+pub struct FlatpakSetup<'a> {
+    realm: &'a Realm,
+}
+
+impl <'a> FlatpakSetup<'a> {
+
+    pub fn new(realm: &'a Realm) -> Self {
+        Self { realm }
+    }
+
+    pub fn setup(&self) -> Result<()> {
+        self.write_desktop_file()?;
+        self.ensure_flatpak_directory()?;
+        Ok(())
+    }
+
+
+    fn write_desktop_file(&self) -> Result<()> {
+        let appdir = Path::new(APPLICATION_DIRECTORY);
+        if !appdir.exists() {
+            util::create_dir(appdir)?;
+            if let Some(parent) = appdir.parent().and_then(|p| p.parent()) {
+                util::chown_tree(parent, (1000,1000), true)?;
+            }
+        }
+        let path = appdir.join(format!("realm-{}.org.gnome.Software.desktop", self.realm.name()));
+        util::write_file(path, GNOME_SOFTWARE_DESKTOP_TEMPLATE.replace("$REALM_NAME", self.realm.name()))?;
+        Ok(())
+    }
+
+    fn ensure_flatpak_directory(&self) -> Result<()> {
+        let path = self.realm.base_path_file("flatpak");
+        if !path.exists() {
+            util::create_dir(&path)?;
+            util::chown_user(&path)?;
+        }
+        Ok(())
+    }
+
+}

libcitadel/src/flatpak/status.rs

@@ -0,0 +1,144 @@
+use std::collections::HashMap;
+use std::fs::File;
+use std::path::{Path, PathBuf};
+use std::time::SystemTime;
+use crate::flatpak::bubblewrap::BubbleWrapStatus;
+use crate::{Realm, Result, util};
+
+
+/// Utility function to read modified time from a path.
+fn modified_time(path: &Path) -> Result<SystemTime> {
+    path.metadata().and_then(|meta| meta.modified())
+        .map_err(context!("failed to read modified time from '{}'", path.display()))
+}
+
+/// Utility function to detect if current modified time of a path
+/// matches an earlier recorded modified time.
+fn modified_changed(path: &Path, old_modified: SystemTime) -> bool {
+    if !path.exists() {
+        // Path existed at some earlier point, so something changed
+        return true;
+    }
+
+    match modified_time(path) {
+        Ok(modified) => old_modified != modified,
+        Err(err) => {
+            // Print a warning but assume change
+            warn!("{}", err);
+            true
+        },
+    }
+}
+
+/// Records the content of single entry in a sandbox status directory.
+///
+/// The path to the status file as well as the last modified time are
+/// recorded so that changes in status of a sandbox can be detected.
+struct StatusEntry {
+    status: BubbleWrapStatus,
+    path: PathBuf,
+    modified: SystemTime,
+}
+
+
+impl StatusEntry {
+
+    fn load_timestamp_and_status(path: &Path) -> Result<Option<(SystemTime, BubbleWrapStatus)>> {
+        if path.exists() {
+            let modified = modified_time(path)?;
+            if let Some(status) = BubbleWrapStatus::parse_file(path)? {
+                return Ok(Some((modified, status)));
+            }
+        }
+        Ok(None)
+    }
+
+    fn load(base_dir: &Path, name: &str) -> Result<Option<Self>> {
+        let path = base_dir.join(name);
+        let result = StatusEntry::load_timestamp_and_status(&path)?
+            .map(|(modified, status)| StatusEntry { status, path, modified });
+        Ok(result)
+    }
+
+    fn is_modified(&self) -> bool {
+        modified_changed(&self.path, self.modified)
+    }
+}
+
+
+/// Holds information about entries in a sandbox status directory.
+///
+/// Bubblewrap accepts a command line argument that asks for status
+/// information to be written as a json structure to a file descriptor.
+///
+pub struct SandboxStatus {
+    base_dir: PathBuf,
+    base_modified: SystemTime,
+    entries: HashMap<String, StatusEntry>,
+}
+
+impl SandboxStatus {
+
+    pub fn need_reload(&self) -> bool {
+        if modified_changed(&self.base_dir, self.base_modified) {
+            return true;
+        }
+        self.entries.values().any(|entry| entry.is_modified())
+    }
+
+    fn process_dir_entry(&mut self, dir_entry: PathBuf) -> Result<()> {
+        fn realm_name_for_path(path: &Path) -> Option<&str> {
+            path.file_name()
+                .and_then(|name| name.to_str())
+                .filter(|name| Realm::is_valid_name(name))
+
+        }
+        if dir_entry.is_file() {
+            if let Some(name) = realm_name_for_path(&dir_entry) {
+                if let Some(entry) = StatusEntry::load(&self.base_dir, name)? {
+                    self.entries.insert(name.to_string(), entry);
+                }
+            }
+        }
+        Ok(())
+    }
+
+    pub fn reload(&mut self) -> Result<()> {
+        self.entries.clear();
+        self.base_modified = modified_time(&self.base_dir)?;
+        let base_dir = self.base_dir.clone();
+        util::read_directory(&base_dir, |entry| {
+            self.process_dir_entry(entry.path())
+        })
+    }
+
+    fn new(base_dir: &Path) -> Result<Self> {
+        let base_dir = base_dir.to_owned();
+        let base_modified = modified_time(&base_dir)?;
+        Ok(SandboxStatus {
+            base_dir,
+            base_modified,
+            entries: HashMap::new(),
+        })
+    }
+
+    pub fn load(directory: impl AsRef<Path>) -> Result<SandboxStatus> {
+        let base_dir = directory.as_ref();
+        if !base_dir.exists() {
+            util::create_dir(base_dir)?;
+        }
+        let mut status = SandboxStatus::new(base_dir)?;
+        status.reload()?;
+        Ok(status)
+    }
+
+    pub fn realm_status(&self, realm: &Realm) -> Option<BubbleWrapStatus> {
+        self.entries.get(realm.name()).map(|entry| entry.status.clone())
+    }
+
+    pub fn new_realm_status_file(&self, realm: &Realm) -> Result<File> {
+        let path = self.base_dir.join(realm.name());
+        File::create(&path)
+            .map_err(context!("failed to open sandbox status file {}", path.display()))
+    }
+}

libcitadel/src/lib.rs

@@ -21,6 +21,8 @@ mod realm;
 pub mod terminal;
 mod system;
 
+pub mod flatpak;
+
 pub use crate::config::OsRelease;
 pub use crate::blockdev::BlockDev;
 pub use crate::cmdline::CommandLine;

libcitadel/src/log.rs

@@ -62,6 +62,11 @@ impl Logger {
         logger.level = level;
     }
 
+    pub fn is_log_level(level: LogLevel) -> bool {
+        let logger = LOGGER.lock().unwrap();
+        logger.level >= level
+    }
+
     pub fn set_log_output(output: Box<dyn LogOutput>) {
         let mut logger = LOGGER.lock().unwrap();
         logger.output = output;

libcitadel/src/realm/config.rs

@@ -77,6 +77,9 @@ pub struct RealmConfig {
     #[serde(rename="use-fuse")]
     pub use_fuse: Option<bool>,
 
+    #[serde(rename="use-flatpak")]
+    pub use_flatpak: Option<bool>,
+
     #[serde(rename="use-gpu")]
     pub use_gpu: Option<bool>,
 
@@ -201,6 +204,7 @@ impl RealmConfig {
             wayland_socket: Some("wayland-0".to_string()),
             use_kvm: Some(false),
             use_fuse: Some(false),
+            use_flatpak: Some(false),
             use_gpu: Some(false),
             use_gpu_card0: Some(false),
             use_network: Some(true),
@@ -233,6 +237,7 @@ impl RealmConfig {
             wayland_socket: None,
             use_kvm: None,
             use_fuse: None,
+            use_flatpak: None,
             use_gpu: None,
             use_gpu_card0: None,
             use_network: None,
@@ -267,6 +272,14 @@ impl RealmConfig {
         self.bool_value(|c| c.use_fuse)
     }
 
+    /// If `true` flatpak directory will be mounted into realm
+    /// and a desktop file will be created to launch gnome-software
+    ///
+    pub fn flatpak(&self) -> bool {
+        self.bool_value(|c| c.use_flatpak)
+    }
+
+
     /// If `true` render node device /dev/dri/renderD128 will be added to realm.
     ///
     /// This enables hardware graphics acceleration in realm.

libcitadel/src/realm/launcher.rs

@@ -60,7 +60,7 @@ impl <'a> RealmLauncher <'a> {
         if config.kvm() {
             self.add_device("/dev/kvm");
         }
-        if config.fuse() {
+        if config.fuse() || config.flatpak() {
             self.add_device("/dev/fuse");
         }
 
@@ -153,6 +153,10 @@ impl <'a> RealmLauncher <'a> {
             writeln!(s, "BindReadOnly=/run/user/1000/{}:/run/user/host/wayland-0", config.wayland_socket())?;
         }
 
+        if config.flatpak() {
+            writeln!(s, "BindReadOnly={}:/var/lib/flatpak", self.realm.base_path_file("flatpak").display())?;
+        }
+
         for bind in config.extra_bindmounts() {
             if Self::is_valid_bind_item(bind) {
                 writeln!(s, "Bind={}", bind)?;

libcitadel/src/realm/manager.rs

@@ -4,6 +4,8 @@ use std::sync::{Arc, RwLock, RwLockReadGuard, RwLockWriteGuard};
 use posix_acl::{ACL_EXECUTE, ACL_READ, PosixACL, Qualifier};
 
 use crate::{Mountpoint, Result, Realms, RealmFS, Realm, util};
+use crate::flatpak::GnomeSoftwareLauncher;
+use crate::flatpak::setup::FlatpakSetup;
 use crate::realm::pidmapper::{PidLookupResult, PidMapper};
 use crate::realmfs::realmfs_set::RealmFSSet;
 
@@ -21,6 +23,7 @@ struct Inner {
     events: RealmEventListener,
     realms: Realms,
     realmfs_set: RealmFSSet,
+    pid_mapper: PidMapper,
 }
 
 impl Inner {
@@ -28,7 +31,8 @@ impl Inner {
         let events = RealmEventListener::new();
         let realms = Realms::load()?;
         let realmfs_set = RealmFSSet::load()?;
-        Ok(Inner { events, realms, realmfs_set })
+        let pid_mapper = PidMapper::new()?;
+        Ok(Inner { events, realms, realmfs_set, pid_mapper })
     }
 }
 
@@ -230,6 +234,10 @@ impl RealmManager {
             self.ensure_run_media_directory()?;
         }
 
+        if realm.config().flatpak() {
+            FlatpakSetup::new(realm).setup()?;
+        }
+
         self.systemd.start_realm(realm, &rootfs)?;
 
         self.create_realm_namefile(realm)?;
@@ -268,6 +276,15 @@ impl RealmManager {
         self.run_in_realm(realm, &["/usr/bin/ln", "-s", "/run/user/host/wayland-0", "/run/user/1000/wayland-0"], false)
     }
 
+    fn stop_gnome_software_sandbox(&self, realm: &Realm) -> Result<()> {
+        let launcher = GnomeSoftwareLauncher::new(realm.clone())?;
+        if launcher.is_running() {
+            info!("Stopping GNOME Software sandbox for {}", realm.name());
+            launcher.quit()?;
+        }
+        Ok(())
+    }
+
     pub fn stop_realm(&self, realm: &Realm) -> Result<()> {
         if !realm.is_active() {
             info!("ignoring stop request on realm '{}' which is not running", realm.name());
@@ -276,6 +293,12 @@ impl RealmManager {
 
         info!("Stopping realm {}", realm.name());
 
+        if realm.config().flatpak() {
+            if let Err(err) = self.stop_gnome_software_sandbox(realm) {
+                warn!("Error stopping GNOME Software sandbox: {}", err);
+            }
+        }
+
         realm.set_active(false);
         self.systemd.stop_realm(realm)?;
         realm.cleanup_rootfs();
@@ -335,8 +358,8 @@ impl RealmManager {
     }
 
     pub fn realm_by_pid(&self, pid: u32) -> PidLookupResult {
-        let mapper = PidMapper::new(self.active_realms(false));
+        let realms = self.realm_list();
-        mapper.lookup_pid(pid as libc::pid_t)
+        self.inner_mut().pid_mapper.lookup_pid(pid as libc::pid_t, realms)
     }
 
     pub fn rescan_realms(&self) -> Result<(Vec<Realm>,Vec<Realm>)> {

libcitadel/src/realm/pidmapper.rs

@@ -1,6 +1,7 @@
 use std::ffi::OsStr;
 use procfs::process::Process;
-use crate::Realm;
+use crate::{Result, Realm};
+use crate::flatpak::{SANDBOX_STATUS_FILE_DIRECTORY, SandboxStatus};
 
 pub enum PidLookupResult {
     Unknown,
@@ -9,14 +10,15 @@ pub enum PidLookupResult {
 }
 
 pub struct PidMapper {
-    active_realms: Vec<Realm>,
+    sandbox_status: SandboxStatus,
     my_pid_ns_id: Option<u64>,
 }
 
 impl PidMapper {
-    pub fn new(active_realms: Vec<Realm>) -> Self {
+    pub fn new() -> Result<Self> {
+        let sandbox_status = SandboxStatus::load(SANDBOX_STATUS_FILE_DIRECTORY)?;
         let my_pid_ns_id = Self::self_pid_namespace_id();
-        PidMapper { active_realms, my_pid_ns_id }
+        Ok(PidMapper { sandbox_status, my_pid_ns_id })
     }
 
     fn read_process(pid: libc::pid_t) -> Option<Process> {
@@ -72,7 +74,30 @@ impl PidMapper {
         Self::read_process(ppid)
     }
 
-    pub fn lookup_pid(&self, pid: libc::pid_t) -> PidLookupResult {
+    fn refresh_sandbox_status(&mut self) -> Result<()> {
+        if self.sandbox_status.need_reload() {
+            self.sandbox_status.reload()?;
+        }
+        Ok(())
+    }
+
+    fn search_sandbox_realms(&mut self, pid_ns: u64, realms: &[Realm]) -> Option<Realm> {
+        if let Err(err) = self.refresh_sandbox_status() {
+            warn!("error reloading sandbox status directory: {}", err);
+            return None;
+        }
+
+        for r in realms {
+            if let Some(status) = self.sandbox_status.realm_status(r) {
+                if status.pid_namespace() == pid_ns {
+                    return Some(r.clone())
+                }
+            }
+        }
+        None
+    }
+
+    pub fn lookup_pid(&mut self, pid: libc::pid_t, realms: Vec<Realm>) -> PidLookupResult {
         const MAX_PARENT_SEARCH: i32 = 8;
         let mut n = 0;
 
@@ -92,13 +117,17 @@ impl PidMapper {
                 return PidLookupResult::Citadel;
             }
 
-            if let Some(realm) = self.active_realms.iter()
+            if let Some(realm) = realms.iter()
-                .find(|r| r.has_pid_ns(pid_ns_id))
+                .find(|r| r.is_active() && r.has_pid_ns(pid_ns_id))
                 .cloned()
             {
                 return PidLookupResult::Realm(realm)
             }
 
+            if let Some(r) = self.search_sandbox_realms(pid_ns_id, &realms) {
+                return PidLookupResult::Realm(r)
+            }
+
             proc = match Self::parent_process(proc) {
                 Some(proc) => proc,
                 None => return PidLookupResult::Unknown,
@@ -108,5 +137,4 @@ impl PidMapper {
         }
         PidLookupResult::Unknown
     }
-
 }

libcitadel/src/realm/realm.rs

@@ -279,6 +279,9 @@ impl Realm {
         symlink::write(&rootfs, self.rootfs_symlink(), false)?;
         symlink::write(mountpoint.path(), self.realmfs_mountpoint_symlink(), false)?;
         symlink::write(self.base_path().join("home"), self.run_path().join("home"), false)?;
+        if self.config().flatpak() {
+            symlink::write(self.base_path().join("flatpak"), self.run_path().join("flatpak"), false)?;
+        }
 
         Ok(rootfs)
     }
@@ -300,6 +303,9 @@ impl Realm {
         Self::remove_symlink(self.realmfs_mountpoint_symlink());
         Self::remove_symlink(self.rootfs_symlink());
         Self::remove_symlink(self.run_path().join("home"));
+        if self.config().flatpak() {
+            Self::remove_symlink(self.run_path().join("flatpak"));
+        }
 
         if let Err(e) = fs::remove_dir(self.run_path()) {
             warn!("failed to remove run directory {}: {}", self.run_path().display(), e);

libcitadel/src/realm/systemd.rs

@@ -31,6 +31,28 @@ impl Systemd {
         if realm.config().ephemeral_home() {
             self.setup_ephemeral_home(realm)?;
         }
+        if realm.config().flatpak() {
+            self.setup_flatpak_workaround(realm)?;
+        }
+        Ok(())
+    }
+
+    // What even is this??
+    //
+    // Good question.
+    //
+    // https://bugzilla.redhat.com/show_bug.cgi?id=2210335#c10
+    //
+    fn setup_flatpak_workaround(&self, realm: &Realm) -> Result<()> {
+        let commands = &[
+            vec!["/usr/bin/mount", "-m", "-t","proc", "proc", "/run/flatpak-workaround/proc"],
+            vec!["/usr/bin/chmod", "700", "/run/flatpak-workaround"],
+        ];
+
+        for cmd in commands {
+            Self::machinectl_shell(realm, cmd, "root", false, true)?;
+        }
+
         Ok(())
     }
 

libcitadel/src/realmfs/resizer.rs

@@ -23,8 +23,8 @@ impl ResizeSize {
 
     pub fn gigs(n: usize) -> Self {
         ResizeSize(BLOCKS_PER_GIG * n)
-
     }
+
     pub fn megs(n: usize) -> Self {
         ResizeSize(BLOCKS_PER_MEG * n)
     }
@@ -45,8 +45,8 @@ impl ResizeSize {
         self.0 / BLOCKS_PER_MEG
     }
 
-    /// If the RealmFS needs to be resized to a larger size, returns the
+    /// If the RealmFS has less than `AUTO_RESIZE_MINIMUM_FREE` blocks free then choose a new
-    /// recommended size.
+    /// size to resize the filesystem to and return it. Otherwise, return `None`
     pub fn auto_resize_size(realmfs: &RealmFS) -> Option<ResizeSize> {
         let sb = match Superblock::load(realmfs.path(), 4096) {
             Ok(sb) => sb,
@@ -56,22 +56,37 @@ impl ResizeSize {
             },
         };
 
-        sb.free_block_count();
         let free_blocks = sb.free_block_count() as usize;
-        if free_blocks < AUTO_RESIZE_MINIMUM_FREE.nblocks() {
+        if free_blocks >= AUTO_RESIZE_MINIMUM_FREE.nblocks() {
-            let metainfo_nblocks = realmfs.metainfo().nblocks() + 1;
+            return None;
-            let increase_multiple = metainfo_nblocks / AUTO_RESIZE_INCREASE_SIZE.nblocks();
+        }
-            let grow_size = (increase_multiple + 1) * AUTO_RESIZE_INCREASE_SIZE.nblocks();
+
-            let mask = grow_size - 1;
+        let metainfo_nblocks = realmfs.metainfo().nblocks();
-            let grow_blocks = (free_blocks + mask) & !mask;
+
-            Some(ResizeSize::blocks(grow_blocks))
+        if metainfo_nblocks >= AUTO_RESIZE_INCREASE_SIZE.nblocks() {
+            return Some(ResizeSize::blocks(metainfo_nblocks + AUTO_RESIZE_INCREASE_SIZE.nblocks()))
+        }
+
+        // If current size is under 4GB (AUTO_RESIZE_INCREASE_SIZE) and raising size to 4GB will create more than the
+        // minimum free space (1GB) then just do that.
+        if free_blocks + (AUTO_RESIZE_INCREASE_SIZE.nblocks() - metainfo_nblocks) >= AUTO_RESIZE_MINIMUM_FREE.nblocks() {
+            Some(AUTO_RESIZE_INCREASE_SIZE)
         } else {
-            None
+            // Otherwise for original size under 4GB, since raising to 4GB is not enough,
+            // raise size to 8GB
+            Some(ResizeSize::blocks(AUTO_RESIZE_INCREASE_SIZE.nblocks() * 2))
         }
     }
 }
 
 const SUPERBLOCK_SIZE: usize = 1024;
+
+/// An EXT4 superblock structure.
+///
+/// A class for reading the first superblock from an EXT4 filesystem
+/// and parsing the Free Block Count field. No other fields are parsed
+/// since this is the only information needed for the resize operation.
+///
 pub struct Superblock([u8; SUPERBLOCK_SIZE]);
 
 impl Superblock {

libcitadel/src/realmfs/update.rs

@@ -76,8 +76,6 @@ impl <'a> Update<'a> {
         }
         self.realmfs.copy_image_file(self.target())?;
 
-        self.truncate_verity()?;
-        self.resize_image_file()?;
         Ok(())
     }
 
@@ -115,9 +113,8 @@ impl <'a> Update<'a> {
     }
 
     // Return size of image file in blocks based on metainfo `nblocks` field.
-    // Include header block in count so add one block
     fn metainfo_nblock_size(&self) -> usize {
-        self.realmfs.metainfo().nblocks() + 1
+        self.realmfs.metainfo().nblocks()
     }
 
     fn unmount_update_image(&mut self) {
@@ -159,7 +156,8 @@ impl <'a> Update<'a> {
     }
 
     fn set_target_len(&self, nblocks: usize) -> Result<()> {
-        let len = (nblocks * BLOCK_SIZE) as u64;
+        // add one block for header block
+        let len = ((nblocks + 1) * BLOCK_SIZE) as u64;
         let f = fs::OpenOptions::new()
             .write(true)
             .open(&self.target)
@@ -176,7 +174,7 @@ impl <'a> Update<'a> {
 
         if self.realmfs.header().has_flag(ImageHeader::FLAG_HASH_TREE) {
             self.set_target_len(metainfo_nblocks)?;
-        } else if file_nblocks > metainfo_nblocks {
+        } else if file_nblocks > (metainfo_nblocks + 1) {
             warn!("RealmFS image size was greater than length indicated by metainfo.nblocks but FLAG_HASH_TREE not set");
         }
         Ok(())
@@ -185,7 +183,7 @@ impl <'a> Update<'a> {
     // If resize was requested, adjust size of update copy of image file.
     fn resize_image_file(&self) -> Result<()> {
         let nblocks = match self.resize {
-            Some(rs) => rs.nblocks() + 1,
+            Some(rs) => rs.nblocks(),
             None => return Ok(()),
         };
 
@@ -224,7 +222,7 @@ impl <'a> Update<'a> {
     fn seal(&mut self) -> Result<()> {
         let nblocks = match self.resize {
             Some(rs) => rs.nblocks(),
-            None => self.metainfo_nblock_size() - 1,
+            None => self.metainfo_nblock_size(),
         };
 
         let salt = hex::encode(randombytes(32));
@@ -232,20 +230,11 @@ impl <'a> Update<'a> {
             .map_err(context!("failed to create verity context for realmfs update image {:?}", self.target()))?;
         let output = verity.generate_image_hashtree_with_salt(&salt, nblocks)
             .map_err(context!("failed to generate dm-verity hashtree for realmfs update image {:?}", self.target()))?;
-        // XXX passes metainfo for nblocks
+
-        //let output = Verity::new(&self.target).generate_image_hashtree_with_salt(&self.realmfs.metainfo(), &salt)?;
         let root_hash = output.root_hash()
             .ok_or_else(|| format_err!("no root hash returned from verity format operation"))?;
         info!("root hash is {}", output.root_hash().unwrap());
 
-        /*
-        let nblocks = match self.resize {
-            Some(rs) => rs.nblocks(),
-            None => self.metainfo_nblock_size() - 1,
-        };
-
-         */
-
         info!("Signing new image with user realmfs keys");
         let metainfo_bytes = RealmFS::generate_metainfo(self.realmfs.name(), nblocks, salt.as_str(), root_hash);
         let keys = self.realmfs.sealing_keys().expect("No sealing keys");

libcitadel/src/util.rs

@@ -7,6 +7,7 @@ use std::env;
 use std::fs::{self, File, DirEntry};
 use std::ffi::CString;
 use std::io::{self, Seek, Read, BufReader, SeekFrom};
+use std::os::fd::AsRawFd;
 use std::time::{SystemTime, UNIX_EPOCH};
 
 use walkdir::WalkDir;
@@ -217,7 +218,8 @@ where
 ///
 pub fn remove_file(path: impl AsRef<Path>) -> Result<()> {
     let path = path.as_ref();
-    if path.exists() {
+    let is_symlink = fs::symlink_metadata(path).is_ok();
+    if is_symlink || path.exists() {
         fs::remove_file(path)
             .map_err(context!("failed to remove file {:?}", path))?;
     }
@@ -368,9 +370,38 @@ pub fn touch_mtime(path: &Path) -> Result<()> {
 
     utimes(path, meta.atime(),mtime)?;
     Ok(())
-
-
-
-
-
 }
+
+pub fn nsenter_netns(netns: &str) -> Result<()> {
+    let mut path = PathBuf::from("/run/netns");
+    path.push(netns);
+    if !path.exists() {
+        bail!("Network namespace '{}' does not exist", netns);
+    }
+    let f = File::open(&path)
+        .map_err(context!("error opening netns file {}", path.display()))?;
+
+    let fd = f.as_raw_fd();
+
+    unsafe {
+        if libc::setns(fd, libc::CLONE_NEWNET) == -1 {
+            let err = io::Error::last_os_error();
+            bail!("failed to setns() into network namespace '{}': {}", netns, err);
+        }
+    }
+    Ok(())
+}
+
+pub fn drop_privileges(uid: u32, gid: u32) -> Result<()> {
+    unsafe {
+        if libc::setgid(gid) == -1 {
+            let err = io::Error::last_os_error();
+            bail!("failed to call setgid({}): {}", gid, err);
+
+        } else if libc::setuid(uid) == -1 {
+            let err = io::Error::last_os_error();
+            bail!("failed to call setuid({}): {}", uid, err);
+        }
+    }
+    Ok(())
+}

systemd/citadel-desktop-watcher.path

@@ -4,6 +4,6 @@ StartLimitIntervalSec=0
 
 [Path]
 PathChanged=/run/citadel/realms/current/current.realm/rootfs/usr/share/applications
-PathChanged=/run/citadel/realms/current/current.realm/rootfs/var/lib/flatpak/exports/share/applications
+PathChanged=/run/citadel/realms/current/current.realm/flatpak/exports/share/applications
 PathChanged=/run/citadel/realms/current/current.realm/home/.local/share/applications
 PathChanged=/run/citadel/realms/current/current.realm/home/.local/share/flatpak/exports/share/applications