install: Add --copy-etc

This allows injection of arbitrary config files from an external
source into the target root.

This is pretty low tech...I'd really like to also support
structured, cleanly "day 2" updatable configmaps, etc.

But there is simply no getting away from the generally wanting the
ability to inject arbitrary machine-local external state today.
It's the lowest common denominitator that applies across many
use cases.

We're agnostic to *how* the data is provided; that could be fetched
from cloud instance metadata, the hypervisor, a USB stick, config
state provided for bootc-image-builder, etc.

Just one technical implementation point, we do handle SELinux labeling here
in a consistent way at least.

Signed-off-by: Colin Walters <walters@verbum.org>

lib/src/install.rs

@@ -11,6 +11,7 @@ mod baseline;
 use std::io::BufWriter;
 use std::io::Write;
 use std::os::fd::AsFd;
+use std::os::unix::fs::DirBuilderExt;
 use std::os::unix::process::CommandExt;
 use std::process::Command;
 use std::str::FromStr;
@@ -21,11 +22,15 @@ use anyhow::{anyhow, Context, Result};
 use camino::Utf8Path;
 use camino::Utf8PathBuf;
 use cap_std::fs::Dir;
+use cap_std_ext::cap_primitives;
 use cap_std_ext::cap_std;
+use cap_std_ext::cap_std::fs::DirBuilder;
+use cap_std_ext::cap_std::io_lifetimes::AsFilelike;
 use cap_std_ext::prelude::CapStdExtDirExt;
 use chrono::prelude::*;
 use clap::ValueEnum;
 use ostree_ext::oci_spec;
+use rustix::fd::AsRawFd;
 use rustix::fs::FileTypeExt;
 use rustix::fs::MetadataExt;
 
@@ -38,6 +43,7 @@ use serde::{Deserialize, Serialize};
 
 use self::baseline::InstallBlockDeviceOpts;
 use crate::containerenv::ContainerExecutionInfo;
+use crate::lsm::Labeler;
 use crate::task::Task;
 use crate::utils::sigpolicy_from_opts;
 
@@ -124,6 +130,27 @@ pub(crate) struct InstallConfigOpts {
     #[serde(default)]
     pub(crate) disable_selinux: bool,
 
+    /// Inject arbitrary files into the target deployment `/etc`.  One can use
+    /// this for example to inject systemd units, or `tmpfiles.d` snippets
+    /// which set up SSH keys.
+    ///
+    /// Files injected this way become "unmanaged state"; they will be carried
+    /// forward across upgrades, but will not otherwise be updated unless
+    /// a secondary mechanism takes ownership thereafter.
+    ///
+    /// This option can be specified multiple times; the files will be copied
+    /// in order.
+    ///
+    /// Any missing parent directories will be implicitly created with root ownership
+    /// and mode 0755.
+    ///
+    /// This option pairs well with additional bind mount
+    /// volumes set up via the container orchestrator, e.g.:
+    /// `podman run ... -v /path/to/config:/tmp/etc <image> bootc install to-disk --copy-etc /tmp/etc`
+    #[clap(long)]
+    #[serde(default)]
+    pub(crate) copy_etc: Option<Vec<Utf8PathBuf>>,
+
     // Only occupy at most this much space (if no units are provided, GB is assumed).
     // Using this option reserves space for partitions created dynamically on the
     // next boot, or by subsequent tools.
@@ -564,11 +591,16 @@ kargs = ["console=ttyS0", "foo=bar"]
     }
 }
 
+struct DeploymentComplete {
+    aleph: InstallAleph,
+    deployment: Dir,
+}
+
 #[context("Creating ostree deployment")]
 async fn initialize_ostree_root_from_self(
     state: &State,
     root_setup: &RootSetup,
-) -> Result<InstallAleph> {
+) -> Result<DeploymentComplete> {
     let rootfs_dir = &root_setup.rootfs_fd;
     let rootfs = root_setup.rootfs.as_path();
     let cancellable = gio::Cancellable::NONE;
@@ -714,7 +746,10 @@ async fn initialize_ostree_root_from_self(
         kernel: uname.release().to_str()?.to_string(),
     };
 
-    Ok(aleph)
+    Ok(DeploymentComplete {
+        aleph,
+        deployment: root,
+    })
 }
 
 #[context("Copying to oci")]
@@ -1058,6 +1093,63 @@ async fn prepare_install(
     Ok(state)
 }
 
+// Backing implementation of --copy-etc; just your basic
+// recursive copy algorithm.  Parent directories are
+// created as necessary
+fn copy_unmanaged_etc(
+    sepolicy: &ostree::SePolicy,
+    src: &Dir,
+    dest: &Dir,
+    path: &mut Utf8PathBuf,
+) -> Result<u64> {
+    let mut r = 0u64;
+    for ent in src.read_dir(&path)? {
+        let ent = ent?;
+        let name = ent.file_name();
+        let name = if let Some(name) = name.to_str() {
+            name
+        } else {
+            anyhow::bail!("Non-UTF8 name: {name:?}");
+        };
+        let meta = ent.metadata()?;
+        path.push(Utf8Path::new(name));
+        r += 1;
+        if meta.is_dir() {
+            if let Some(parent) = path.parent() {
+                dest.create_dir_all(parent)
+                    .with_context(|| format!("Creating {parent}"))?;
+            }
+            if !dest.try_exists(&path)? {
+                let mut db = DirBuilder::new();
+                db.mode(meta.mode());
+                let label = Labeler::new(sepolicy, path, meta.mode())?;
+                dest.create_dir_with(&path, &db)
+                    .with_context(|| format!("Creating {path:?}"))?;
+                drop(label);
+            }
+            r += copy_unmanaged_etc(sepolicy, src, dest, path)?;
+        } else {
+            dest.remove_file_optional(&path)?;
+            let label = Labeler::new(sepolicy, path, meta.mode())?;
+            if meta.is_symlink() {
+                let link_target = cap_primitives::fs::read_link_contents(
+                    &src.as_filelike_view(),
+                    path.as_std_path(),
+                )
+                .context("Reading symlink")?;
+                cap_primitives::fs::symlink_contents(link_target, &dest.as_filelike_view(), &path)
+                    .with_context(|| format!("Writing symlink {path:?}"))?;
+            } else {
+                src.copy(&path, dest, &path)
+                    .with_context(|| format!("Copying {path:?}"))?;
+            }
+            drop(label);
+        }
+        assert!(path.pop());
+    }
+    Ok(r)
+}
+
 async fn install_to_filesystem_impl(state: &State, rootfs: &mut RootSetup) -> Result<()> {
     if state.override_disable_selinux {
         rootfs.kargs.push("selinux=0".to_string());
@@ -1071,16 +1163,41 @@ async fn install_to_filesystem_impl(state: &State, rootfs: &mut RootSetup) -> Re
     tracing::debug!("boot uuid={boot_uuid}");
 
     // Write the aleph data that captures the system state at the time of provisioning for aid in future debugging.
-    {
-        let aleph = initialize_ostree_root_from_self(state, rootfs).await?;
-        rootfs
-            .rootfs_fd
-            .atomic_replace_with(BOOTC_ALEPH_PATH, |f| {
-                serde_json::to_writer(f, &aleph)?;
-                anyhow::Ok(())
-            })
-            .context("Writing aleph version")?;
-    }
+    let deployresult = initialize_ostree_root_from_self(state, rootfs).await?;
+    rootfs
+        .rootfs_fd
+        .atomic_replace_with(BOOTC_ALEPH_PATH, |f| {
+            serde_json::to_writer(f, &deployresult.aleph)?;
+            anyhow::Ok(())
+        })
+        .context("Writing aleph version")?;
+    let sepolicy =
+        ostree::SePolicy::new_at(deployresult.deployment.as_raw_fd(), gio::Cancellable::NONE)?;
+
+    // Copy unmanaged configuration
+    let target_etc = deployresult
+        .deployment
+        .open_dir("etc")
+        .context("Opening deployment /etc")?;
+    let copy_etc = state
+        .config_opts
+        .copy_etc
+        .iter()
+        .flatten()
+        .cloned()
+        .collect::<Vec<_>>();
+    tokio::task::spawn_blocking(move || {
+        for src in copy_etc {
+            println!("Injecting configuration from {src}");
+            let src = Dir::open_ambient_dir(&src, cap_std::ambient_authority())
+                .with_context(|| format!("Opening {src}"))?;
+            let mut pb = ".".into();
+            let n = copy_unmanaged_etc(&sepolicy, &src, &target_etc, &mut pb)?;
+            tracing::debug!("Copied config files: {n}");
+        }
+        anyhow::Ok(())
+    })
+    .await??;
 
     crate::bootloader::install_via_bootupd(&rootfs.device, &rootfs.rootfs, &state.config_opts)?;
     tracing::debug!("Installed bootloader");
@@ -1092,6 +1209,8 @@ async fn install_to_filesystem_impl(state: &State, rootfs: &mut RootSetup) -> Re
         .args(["+i", "."])
         .run()?;
 
+    drop(deployresult);
+
     // Finalize mounted filesystems
     if !rootfs.is_alongside {
         let bootfs = rootfs.rootfs.join("boot");
@@ -1369,11 +1488,78 @@ pub(crate) async fn install_to_filesystem(opts: InstallToFilesystemOpts) -> Resu
     Ok(())
 }
 
-#[test]
-fn install_opts_serializable() {
-    let c: InstallToDiskOpts = serde_json::from_value(serde_json::json!({
-        "device": "/dev/vda"
-    }))
-    .unwrap();
-    assert_eq!(c.block_opts.device, "/dev/vda");
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn install_opts_serializable() {
+        let c: InstallToDiskOpts = serde_json::from_value(serde_json::json!({
+            "device": "/dev/vda"
+        }))
+        .unwrap();
+        assert_eq!(c.block_opts.device, "/dev/vda");
+    }
+
+    #[test]
+    fn test_copy_etc() -> Result<()> {
+        use std::path::PathBuf;
+        fn impl_count(d: &Dir, path: &mut PathBuf) -> Result<u64> {
+            let mut c = 0u64;
+            for ent in d.read_dir(&path)? {
+                let ent = ent?;
+                path.push(ent.file_name());
+                c += 1;
+                if ent.file_type()?.is_dir() {
+                    c += impl_count(d, path)?;
+                }
+                path.pop();
+            }
+            return Ok(c);
+        }
+        fn count(d: &Dir) -> Result<u64> {
+            let mut p = PathBuf::from(".");
+            impl_count(d, &mut p)
+        }
+
+        use cap_std_ext::cap_tempfile::TempDir;
+        let tmproot = TempDir::new(cap_std::ambient_authority())?;
+        let src_etc = TempDir::new(cap_std::ambient_authority())?;
+
+        let init_tmproot = || -> Result<()> {
+            tmproot.write("foo.conf", "somefoo")?;
+            tmproot.symlink("foo.conf", "foo-link.conf")?;
+            tmproot.create_dir_all("systemd/system")?;
+            tmproot.write("systemd/system/foo.service", "[fooservice]")?;
+            tmproot.write("systemd/system/other.service", "[otherservice]")?;
+            Ok(())
+        };
+
+        let mut pb = ".".into();
+        let sepolicy = &ostree::SePolicy::new_at(tmproot.as_raw_fd(), gio::Cancellable::NONE)?;
+        // First, a no-op
+        copy_unmanaged_etc(sepolicy, &src_etc, &tmproot, &mut pb).unwrap();
+        assert_eq!(count(&tmproot).unwrap(), 0);
+
+        init_tmproot()?;
+
+        // Another no-op but with data in dest already
+        copy_unmanaged_etc(sepolicy, &src_etc, &tmproot, &mut pb).unwrap();
+        assert_eq!(count(&tmproot).unwrap(), 6);
+
+        src_etc.write("injected.conf", "injected")?;
+        copy_unmanaged_etc(sepolicy, &src_etc, &tmproot, &mut pb).unwrap();
+        assert_eq!(count(&tmproot).unwrap(), 7);
+
+        src_etc.create_dir_all("systemd/system")?;
+        src_etc.write("systemd/system/foo.service", "[overwrittenfoo]")?;
+        copy_unmanaged_etc(sepolicy, &src_etc, &tmproot, &mut pb).unwrap();
+        assert_eq!(count(&tmproot).unwrap(), 7);
+        assert_eq!(
+            tmproot.read_to_string("systemd/system/foo.service")?,
+            "[overwrittenfoo]"
+        );
+
+        Ok(())
+    }
 }

lib/src/lsm.rs

@@ -161,6 +161,33 @@ pub(crate) fn lsm_label(target: &Utf8Path, as_path: &Utf8Path, recurse: bool) ->
         .run()
 }
 
+#[cfg(feature = "install")]
+pub(crate) struct Labeler<'a> {
+    _sepolicy: &'a ostree::SePolicy,
+}
+
+#[cfg(feature = "install")]
+impl<'a> Labeler<'a> {
+    pub(crate) fn new(
+        sepolicy: &'a ostree::SePolicy,
+        path: &'_ Utf8Path,
+        mode: u32,
+    ) -> Result<Self> {
+        sepolicy.setfscreatecon(path.as_str(), mode)?;
+        Ok(Self {
+            _sepolicy: sepolicy,
+        })
+    }
+}
+
+#[cfg(feature = "install")]
+impl<'a> Drop for Labeler<'a> {
+    fn drop(&mut self) {
+        // TODO: add better bindings for only calling this if we did find a label
+        ostree::SePolicy::fscreatecon_cleanup()
+    }
+}
+
 #[cfg(feature = "install")]
 pub(crate) fn xattrs_have_selinux(xattrs: &ostree::glib::Variant) -> bool {
     let v = xattrs.data_as_bytes();

tests/kolainst/install

@@ -29,8 +29,13 @@ case "${AUTOPKGTEST_REBOOT_MARK:-}" in
     COPY usr usr
 EOF
     podman build -t localhost/testimage .
-    podman run --rm -ti --privileged --pid=host --env RUST_LOG=error,bootc_lib::install=debug \
-      localhost/testimage bootc install to-disk --skip-fetch-check --karg=foo=bar ${DEV}
+    mkdir -p injected-config/etc/systemd/system/
+    cat > injected-config/etc/systemd/system/injected.service << 'EOF'
+[Service]
+ExecStart=echo injected
+EOF
+    podman run --rm -ti --privileged --pid=host -v ./injected-config:/config --env RUST_LOG=error,bootc_lib::install=debug \
+      localhost/testimage bootc install to-disk --copy-etc /config --skip-fetch-check --karg=foo=bar ${DEV}
     # In theory we could e.g. wipe the bootloader setup on the primary disk, then reboot;
     # but for now let's just sanity test that the install command executes.
     lsblk ${DEV}
@@ -39,6 +44,9 @@ EOF
     grep localtestkarg=somevalue /var/mnt/loader/entries/*.conf
     grep -Ee '^linux /boot/ostree' /var/mnt/loader/entries/*.conf
     umount /var/mnt
+    mount /dev/vda4 /var/mnt
+    diff /var/mnt/ostree/deploy/default/deploy/*.0/etc/systemd/system/injected.service injected-config/etc/systemd/system/injected.service
+    umount /var/mnt
     echo "ok install"
 
     # Now test install to-filesystem