Change rootless required function and privilege decision

crates/libcgroups/src/common.rs

@@ -25,6 +25,17 @@ use super::stats::Stats;
 pub const CGROUP_PROCS: &str = "cgroup.procs";
 pub const DEFAULT_CGROUP_ROOT: &str = "/sys/fs/cgroup";
 
+#[cfg(feature = "systemd")]
+#[inline]
+fn is_true_root() -> bool {
+    if !nix::unistd::geteuid().is_root() {
+        return false;
+    }
+    let uid_map_path = "/proc/self/uid_map";
+    let content = std::fs::read_to_string(uid_map_path)
+        .unwrap_or_else(|_| panic!("failed to read {}", uid_map_path));
+    content.contains("4294967295")
+}
 pub trait CgroupManager {
     type Error;
 
@@ -388,7 +399,7 @@ fn create_systemd_cgroup_manager(
         );
     }
 
-    let use_system = nix::unistd::geteuid().is_root();
+    let use_system = is_true_root();
 
     tracing::info!(
         "systemd cgroup manager with system bus {} will be used",

crates/libcontainer/src/container/init_builder.rs

@@ -13,7 +13,7 @@ use crate::{
     error::{ErrInvalidSpec, LibcontainerError, MissingSpecError},
     notify_socket::NOTIFY_FILE,
     process::args::ContainerType,
-    tty, user_ns,
+    tty, user_ns, utils,
 };
 
 use super::{
@@ -87,6 +87,11 @@ impl InitContainerBuilder {
         };
 
         let user_ns_config = UserNamespaceConfig::new(&spec)?;
+
+        if utils::rootless_required() && !utils::is_in_new_userns() && user_ns_config.is_none() {
+            return Err(LibcontainerError::NoUserNamespace);
+        }
+
         let config = YoukiConfig::from_spec(&spec, container.id(), user_ns_config.is_some())?;
         config.save(&container_dir).map_err(|err| {
             tracing::error!(?container_dir, "failed to save config: {}", err);

crates/libcontainer/src/container/tenant_builder.rs

@@ -121,6 +121,10 @@ impl TenantContainerBuilder {
         let use_systemd = self.should_use_systemd(&container);
         let user_ns_config = UserNamespaceConfig::new(&spec)?;
 
+        if utils::rootless_required() && !utils::is_in_new_userns() && user_ns_config.is_none() {
+            return Err(LibcontainerError::NoUserNamespace);
+        }
+
         let (read_end, write_end) =
             pipe2(OFlag::O_CLOEXEC).map_err(LibcontainerError::OtherSyscall)?;
 

crates/libcontainer/src/error.rs

@@ -22,6 +22,8 @@ pub enum LibcontainerError {
     InvalidInput(String),
     #[error("requires at least one executors")]
     NoExecutors,
+    #[error("rootless container requires valid user namespace definition")]
+    NoUserNamespace,
 
     // Invalid inputs
     #[error(transparent)]

crates/libcontainer/src/process/container_init_process.rs

@@ -376,7 +376,8 @@ pub fn container_init_process(
             })?;
         }
 
-        let bind_service = namespaces.get(LinuxNamespaceType::User)?.is_some();
+        let bind_service =
+            namespaces.get(LinuxNamespaceType::User)?.is_some() || utils::is_in_new_userns();
         let rootfs = RootFS::new();
         rootfs
             .prepare_rootfs(

crates/libcontainer/src/user_ns.rs

@@ -1,5 +1,6 @@
 use crate::error::MissingSpecError;
 use crate::namespaces::{NamespaceError, Namespaces};
+use crate::utils;
 use nix::unistd::Pid;
 use oci_spec::runtime::{Linux, LinuxIdMapping, LinuxNamespace, LinuxNamespaceType, Mount, Spec};
 use std::fs;
@@ -85,8 +86,6 @@ type Result<T> = std::result::Result<T, UserNamespaceError>;
 pub enum ValidateSpecError {
     #[error(transparent)]
     MissingSpec(#[from] crate::error::MissingSpecError),
-    #[error("rootless container requires valid user namespace definition")]
-    NoUserNamespace, // TODO fix this while fixing podman
     #[error("new user namespace requires valid uid mappings")]
     NoUIDMappings,
     #[error("new user namespace requires valid gid mappings")]
@@ -152,13 +151,6 @@ impl UserNamespaceConfig {
             .get(LinuxNamespaceType::User)
             .map_err(ValidateSpecError::Namespaces)?;
 
-        // If conditions requires us to use rootless, we must either create a new
-        // user namespace or enter an existing.
-        // TODO FIX THIS FOR ROOTLESS
-        if rootless_required() && user_namespace.is_none() {
-            return Err(UserNamespaceError::NoUserNamespace);
-        }
-
         if user_namespace.is_some() && user_namespace.unwrap().path().is_none() {
             tracing::debug!("container with new user namespace should be created");
 
@@ -225,22 +217,12 @@ impl TryFrom<&Linux> for UserNamespaceConfig {
             uid_mappings: linux.uid_mappings().to_owned(),
             gid_mappings: linux.gid_mappings().to_owned(),
             user_namespace: user_namespace.cloned(),
-            privileged: nix::unistd::geteuid().is_root(),
+            privileged: !utils::rootless_required(),
             id_mapper: UserNamespaceIDMapper::new(),
         })
     }
 }
 
-/// Checks if rootless mode should be used
-// TODO fix this along with podman
-pub fn rootless_required() -> bool {
-    if !nix::unistd::geteuid().is_root() {
-        return true;
-    }
-
-    matches!(std::env::var("YOUKI_USE_ROOTLESS").as_deref(), Ok("true"))
-}
-
 pub fn unprivileged_user_ns_enabled() -> Result<bool> {
     let user_ns_sysctl = Path::new("/proc/sys/kernel/unprivileged_userns_clone");
     if !user_ns_sysctl.exists() {
@@ -269,10 +251,6 @@ fn validate_spec_for_new_user_ns(spec: &Spec) -> std::result::Result<(), Validat
         "validating spec for container with new user namespace"
     );
     let linux = spec.linux().as_ref().ok_or(MissingSpecError::Linux)?;
-    let namespaces = Namespaces::try_from(linux.namespaces().as_ref())?;
-    if namespaces.get(LinuxNamespaceType::User)?.is_none() {
-        return Err(ValidateSpecError::NoUserNamespace);
-    }
 
     let gid_mappings = linux
         .gid_mappings()
@@ -303,9 +281,8 @@ fn validate_spec_for_new_user_ns(spec: &Spec) -> std::result::Result<(), Validat
         .as_ref()
         .and_then(|process| process.user().additional_gids().as_ref())
     {
-        let privileged = nix::unistd::geteuid().is_root();
+        let privileged = !utils::rootless_required();
 
-        // TODO fix this along with fixes for podman
         match (privileged, additional_gids.is_empty()) {
             (true, false) => {
                 for gid in additional_gids {
@@ -516,19 +493,6 @@ mod tests {
             .size(10_u32)
             .build()?];
 
-        let linux_no_userns = LinuxBuilder::default()
-            .namespaces(vec![])
-            .uid_mappings(uid_mappings.clone())
-            .gid_mappings(gid_mappings.clone())
-            .build()?;
-        assert!(validate_spec_for_new_user_ns(
-            &SpecBuilder::default()
-                .linux(linux_no_userns)
-                .build()
-                .unwrap()
-        )
-        .is_err());
-
         let linux_uid_empty = LinuxBuilder::default()
             .namespaces(vec![userns.clone()])
             .uid_mappings(vec![])

crates/libcontainer/src/utils.rs

@@ -258,6 +258,21 @@ pub fn ensure_procfs(path: &Path) -> Result<(), EnsureProcfsError> {
     Ok(())
 }
 
+pub fn is_in_new_userns() -> bool {
+    let uid_map_path = "/proc/self/uid_map";
+    let content = std::fs::read_to_string(uid_map_path)
+        .unwrap_or_else(|_| panic!("failed to read {}", uid_map_path));
+    !content.contains("4294967295")
+}
+
+/// Checks if rootless mode needs to be used
+pub fn rootless_required() -> bool {
+    if !nix::unistd::geteuid().is_root() {
+        return true;
+    }
+    is_in_new_userns()
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

crates/youki/src/observability.rs

@@ -73,7 +73,13 @@ where
     let log_level_filter = tracing_subscriber::filter::LevelFilter::from(level);
     let log_format = detect_log_format(config.log_format.as_deref())
         .with_context(|| "failed to detect log format")?;
-    let systemd_journald = if config.systemd_log {
+
+    #[cfg(debug_assertions)]
+    let journald = true;
+    #[cfg(not(debug_assertions))]
+    let journald = config.systemd_log;
+
+    let systemd_journald = if journald {
         Some(tracing_journald::layer()?.with_syslog_identifier("youki".to_string()))
     } else {
         None

crates/youki/src/rootpath.rs

@@ -1,6 +1,6 @@
 use anyhow::{bail, Result};
-use libcontainer::user_ns::rootless_required;
 use libcontainer::utils::create_dir_all_with_mode;
+use libcontainer::utils::rootless_required;
 use nix::libc;
 use nix::sys::stat::Mode;
 use nix::unistd::getuid;