bootc_lib/bootc_composefs/

repo.rs

//! Composefs repository lifecycle and OCI pull paths.
//!
//! This module owns how OCI images get into the composefs object store.
//! There are two pull paths, selected by the `use_unified` flag:
//!
//! ## Direct pull (`use_unified = false`)
//!
//! `pull_composefs_direct` fetches from the source transport (registry, OCI
//! dir, etc.) straight into the composefs repo via `composefs_oci::pull` with
//! default options. No containers-storage involvement.
//!
//! ## Unified pull (`use_unified = true`)
//!
//! `pull_composefs_unified` is the two-stage path that populates all three
//! stores (see [`crate::store`] for the architecture overview):
//!
//! **Stage 1** — Pull into bootc-owned containers-storage via
//! `CStorage::pull_with_progress` (or `pull_from_host_storage` if the image
//! already exists in the default podman store, saving a network round-trip).
//!
//! **Stage 2** — `composefs_oci::pull` with `LocalFetchOpt::ZeroCopy` and
//! `storage_root` pointing at the containers-storage directory. composefs-ctl
//! walks the overlay `diff/` directories and FICLONEs each file into the
//! composefs object store keyed by its SHA-512 fsverity digest. On a
//! reflink-capable filesystem this is near-instantaneous and consumes no
//! additional disk space.
//!
//! The caller provides `storage_path` as an absolute filesystem path string
//! (not a `Dir` fd) because composefs-ctl passes it to a child skopeo process.
//! It is derived from the physical root fd via `/proc/self/fd/{fd}` readlink.
//!
//! ## Entry points
//!
//! - [`pull_composefs_repo`] — upgrade/switch on a composefs-booted system.
//! - [`initialize_composefs_repository`] — `bootc install` with the composefs
//!   backend.

use fn_error_context::context;
use std::sync::Arc;

use anyhow::{Context, Result};

use composefs::fsverity::{FsVerityHashValue, Sha512HashValue};
use composefs::repository::RepositoryConfig;
use composefs_boot::bootloader::{BootEntry as ComposefsBootEntry, get_boot_resources};
use composefs_ctl::composefs;
use composefs_ctl::composefs_boot;
use composefs_ctl::composefs_oci;
use composefs_oci::{
    LocalFetchOpt, PullOptions, PullResult,
    image::create_filesystem as create_composefs_filesystem, tag_image,
};

use ostree_ext::containers_image_proxy;

use cap_std_ext::cap_std::{ambient_authority, fs::Dir};

use crate::composefs_consts::BOOTC_TAG_PREFIX;
use crate::install::{RootSetup, State};
use crate::lsm;
use crate::podstorage::CStorage;

/// Create a composefs OCI tag name for the given manifest digest.
///
/// Returns a tag like `localhost/bootc-sha256:abc...` which acts as a GC root
/// in the composefs repository, keeping the manifest, config, and all layer
/// splitstreams alive.
pub(crate) fn bootc_tag_for_manifest(manifest_digest: &str) -> String {
    format!("{BOOTC_TAG_PREFIX}{manifest_digest}")
}

pub(crate) fn open_composefs_repo(rootfs_dir: &Dir) -> Result<crate::store::ComposefsRepository> {
    crate::store::ComposefsRepository::open_path(rootfs_dir, "composefs")
        .context("Failed to open composefs repository")
}

pub(crate) async fn initialize_composefs_repository(
    state: &State,
    root_setup: &RootSetup,
    allow_missing_fsverity: bool,
    use_unified: bool,
) -> Result<PullResult<Sha512HashValue>> {
    const COMPOSEFS_REPO_INIT_JOURNAL_ID: &str = "5d4c3b2a1f0e9d8c7b6a5f4e3d2c1b0a9";

    let rootfs_dir = &root_setup.physical_root;
    let image_name = &state.source.imageref.name;
    let transport = &state.source.imageref.transport;

    tracing::info!(
        message_id = COMPOSEFS_REPO_INIT_JOURNAL_ID,
        bootc.operation = "repository_init",
        bootc.source_image = %image_name,
        bootc.transport = %transport,
        bootc.allow_missing_fsverity = allow_missing_fsverity,
        bootc.unified_storage = use_unified,
        "Initializing composefs repository for image {}:{}",
        transport,
        image_name
    );

    crate::store::ensure_composefs_dir(rootfs_dir)?;

    let config = RepositoryConfig::new(composefs::fsverity::Algorithm::SHA512);
    let config = if allow_missing_fsverity {
        config.set_insecure()
    } else {
        config
    };
    let (repo, _created) =
        crate::store::ComposefsRepository::init_path(rootfs_dir, "composefs", config)
            .context("Failed to initialize composefs repository")?;

    let imgref: containers_image_proxy::ImageReference = state
        .source
        .imageref
        .to_string()
        .as_str()
        .try_into()
        .context("Parsing source image reference")?;

    // Ensure the compatibility symlink ostree/bootc -> ../composefs/bootc
    // exists.  This is needed for LBI and (when unified storage is enabled)
    // for containers-storage under composefs/bootc/storage.  The existing
    // /usr/lib/bootc/storage symlink and all runtime code using
    // ostree/bootc/storage depend on this link.
    crate::store::ensure_composefs_bootc_link(rootfs_dir)?;

    let repo = Arc::new(repo);

    let pull_result = if use_unified {
        // Unified path: first into containers-storage on the target
        // rootfs, then cstor zero-copy into composefs. This ensures the image
        // is available for `podman run` from first boot.
        let sepolicy = state.load_policy()?;
        let run = Dir::open_ambient_dir("/run", ambient_authority())?;
        let imgstore = CStorage::create(rootfs_dir, &run, sepolicy.as_ref())?;
        let storage_path = root_setup.physical_root_path.join(CStorage::subpath());

        let r = pull_composefs_unified(&imgstore, storage_path.as_str(), &repo, &imgref).await?;

        // SELinux-label the containers-storage now that all pulls are done.
        imgstore
            .ensure_labeled()
            .context("SELinux labeling of containers-storage")?;
        r
    } else {
        // Direct path: pull directly into composefs via skopeo, without
        // containers-storage as intermediary.
        pull_composefs_direct(&repo, &imgref).await?
    };

    // Tag the manifest as a bootc-owned GC root.
    let tag = bootc_tag_for_manifest(&pull_result.manifest_digest.to_string());
    tag_image(&*repo, &pull_result.manifest_digest, &tag)
        .context("Tagging pulled image as bootc GC root")?;

    tracing::info!(
        message_id = COMPOSEFS_REPO_INIT_JOURNAL_ID,
        bootc.operation = "repository_init",
        bootc.manifest_digest = %pull_result.manifest_digest,
        bootc.manifest_verity = pull_result.manifest_verity.to_hex(),
        bootc.config_digest = %pull_result.config_digest,
        bootc.config_verity = pull_result.config_verity.to_hex(),
        bootc.tag = tag,
        "Pulled image into composefs repository",
    );

    Ok(pull_result)
}

/// Result of pulling a composefs repository, including the OCI manifest digest
/// needed to reconstruct image metadata from the local composefs repo.
pub(crate) struct PullRepoResult {
    pub(crate) repo: crate::store::ComposefsRepository,
    pub(crate) entries: Vec<ComposefsBootEntry<Sha512HashValue>>,
    pub(crate) id: Sha512HashValue,
    /// The OCI manifest content digest (e.g. "sha256:abc...")
    pub(crate) manifest_digest: String,
}

/// Pull an image directly into the composefs repository via skopeo.
///
/// This is the default path: the image is fetched directly from the source
/// transport (registry, oci directory, etc.) into the composefs repo without
/// going through containers-storage first.
async fn pull_composefs_direct(
    repo: &Arc<crate::store::ComposefsRepository>,
    imgref: &containers_image_proxy::ImageReference,
) -> Result<PullResult<Sha512HashValue>> {
    let imgref_str = imgref.to_string();
    tracing::info!("Direct pull: fetching {imgref_str} into composefs repository");

    let mut config = crate::deploy::new_proxy_config();
    ostree_ext::container::apply_container_proxy_opts_for_transport(&mut config, imgref.transport)?;

    let pull_result = composefs_oci::pull(
        repo,
        &imgref_str,
        None,
        PullOptions {
            img_proxy_config: Some(config),
            ..Default::default()
        },
    )
    .await
    .context("Pulling image into composefs repository")?;

    Ok(pull_result)
}

/// Pull an image via unified storage: first into bootc-owned containers-storage,
/// then from there into the composefs repository via cstor (zero-copy
/// reflink/hardlink).
///
/// The caller provides:
/// - `imgstore`: the bootc-owned `CStorage` instance (may be on an arbitrary
///   mount point during install, or under `/sysroot` during upgrade)
/// - `storage_path`: the absolute filesystem path to that containers-storage
///   directory, so cstor and skopeo can find it (e.g.
///   `/mnt/sysroot/ostree/bootc/storage` during install, or
///   `/sysroot/ostree/bootc/storage` during upgrade)
///
/// This ensures the image is available in containers-storage for `podman run`
/// while also populating the composefs repo for booting.
async fn pull_composefs_unified(
    imgstore: &CStorage,
    storage_path: &str,
    repo: &Arc<crate::store::ComposefsRepository>,
    imgref: &containers_image_proxy::ImageReference,
) -> Result<PullResult<Sha512HashValue>> {
    let image = &imgref.name;

    // Stage 1: get the image into bootc-owned containers-storage.
    if imgref.transport == containers_image_proxy::Transport::ContainerStorage {
        // The image is in the default containers-storage (/var/lib/containers/storage).
        // Copy it into bootc-owned storage.
        tracing::info!("Unified pull: copying {image} from host containers-storage");
        imgstore
            .pull_from_host_storage(image)
            .await
            .context("Copying image from host containers-storage into bootc storage")?;
    } else {
        // For registry (docker://), oci:, docker-daemon:, etc. — pull
        // via the native podman API with streaming progress display.
        let pull_ref = imgref.to_string();
        tracing::info!("Unified pull: fetching {pull_ref} into containers-storage");
        imgstore
            .pull_with_progress(&pull_ref)
            .await
            .context("Pulling image into bootc containers-storage")?;
    }

    // Stage 2: import full OCI structure (layers + config + manifest) from
    // containers-storage into composefs via cstor (zero-copy reflink/hardlink).
    let cstor_imgref_str = format!("containers-storage:{image}");
    tracing::info!("Unified pull: importing from {cstor_imgref_str} (zero-copy)");

    let storage = std::path::Path::new(storage_path);
    let pull_opts = PullOptions {
        // The image is already in bootc-owned containers-storage at this point
        // (placed there by Stage 1 of the unified pull). Use ZeroCopy so we
        // actually import via reflink/hardlink and fail loudly if that isn't
        // possible — a plain copy fallback here would mean Stage 1 and Stage 2
        // are on different filesystems or the storage root is wrong.
        local_fetch: LocalFetchOpt::ZeroCopy,
        storage_root: Some(storage),
        ..Default::default()
    };
    let pull_result = composefs_oci::pull(repo, &cstor_imgref_str, None, pull_opts)
        .await
        .context("Importing from containers-storage into composefs")?;

    Ok(pull_result)
}

/// Pulls an image into a composefs repository at /sysroot.
///
/// When `use_unified` is true, the image is first pulled into bootc-owned
/// containers-storage (so it's available for `podman run`), then imported
/// from there into the composefs repo via zero-copy reflinks.
///
/// When `use_unified` is false (the default), the image is pulled directly
/// into the composefs repo via skopeo.
///
/// Checks for boot entries in the image and returns them.
#[context("Pulling composefs repository")]
pub(crate) async fn pull_composefs_repo(
    spec_imgref: &crate::spec::ImageReference,
    allow_missing_fsverity: bool,
    use_unified: bool,
) -> Result<PullRepoResult> {
    const COMPOSEFS_PULL_JOURNAL_ID: &str = "4c3b2a1f0e9d8c7b6a5f4e3d2c1b0a9f8";

    let imgref = spec_imgref.to_image_proxy_ref()?;

    tracing::info!(
        message_id = COMPOSEFS_PULL_JOURNAL_ID,
        bootc.operation = "pull",
        bootc.source_image = &spec_imgref.image,
        bootc.transport = %imgref.transport,
        bootc.allow_missing_fsverity = allow_missing_fsverity,
        bootc.unified_storage = use_unified,
        "Pulling composefs image {imgref}",
    );

    let rootfs_dir = Dir::open_ambient_dir("/sysroot", ambient_authority())?;

    let mut repo = open_composefs_repo(&rootfs_dir).context("Opening composefs repo")?;
    if allow_missing_fsverity {
        repo.set_insecure();
    }

    let repo = Arc::new(repo);

    // Upgrade any old-format OCI images before pulling.  Old bootc
    // (composefs-rs ≤ 2203e8f) did not add IMAGE_REF_KEY to config
    // splitstreams, so the new GC's tag-based stream walk cannot reach
    // their layer objects.  upgrade_repo() rewrites those config
    // splitstreams in place before we add a new deployment, ensuring all
    // existing deployments are GC-safe.  It is idempotent and fast when
    // images are already in the current format.
    let upgrade_result =
        composefs_oci::upgrade_repo(&repo).context("Upgrading old-format OCI images")?;
    if upgrade_result.upgraded > 0 {
        tracing::info!(
            "Upgraded {} old-format OCI image(s) to current format",
            upgrade_result.upgraded
        );
    }

    let pull_result = if use_unified {
        // Create bootc-owned containers-storage on the rootfs.
        // Load SELinux policy from the running system so newly pulled layers
        // get the correct container_var_lib_t labels.
        let root = Dir::open_ambient_dir("/", ambient_authority())?;
        let sepolicy = lsm::new_sepolicy_at(&root)?;
        let run = Dir::open_ambient_dir("/run", ambient_authority())?;
        let imgstore = CStorage::create(&rootfs_dir, &run, sepolicy.as_ref())?;
        let storage_path = format!("/sysroot/{}", CStorage::subpath());

        pull_composefs_unified(&imgstore, &storage_path, &repo, &imgref).await?
    } else {
        pull_composefs_direct(&repo, &imgref).await?
    };

    // Tag the manifest as a bootc-owned GC root.
    let tag = bootc_tag_for_manifest(&pull_result.manifest_digest.to_string());
    tag_image(&*repo, &pull_result.manifest_digest, &tag)
        .context("Tagging pulled image as bootc GC root")?;

    tracing::info!(
        message_id = COMPOSEFS_PULL_JOURNAL_ID,
        bootc.operation = "pull",
        bootc.manifest_digest = %pull_result.manifest_digest,
        bootc.manifest_verity = pull_result.manifest_verity.to_hex(),
        bootc.config_digest = %pull_result.config_digest,
        bootc.config_verity = pull_result.config_verity.to_hex(),
        bootc.tag = tag,
        "Pulled image into composefs repository",
    );

    // Generate the bootable EROFS image (idempotent).
    let id = composefs_oci::generate_boot_image(&repo, &pull_result.manifest_digest)
        .context("Generating bootable EROFS image")?;

    // Get boot entries from the OCI filesystem (untransformed).
    let fs = create_composefs_filesystem(&*repo, &pull_result.config_digest, None)
        .context("Creating composefs filesystem for boot entry discovery")?;
    let entries =
        get_boot_resources(&fs, &*repo).context("Extracting boot entries from OCI image")?;

    // Unwrap the Arc to get the owned repo back.
    let mut repo = Arc::try_unwrap(repo).map_err(|_| {
        anyhow::anyhow!("BUG: Arc<Repository> still has other references after pull completed")
    })?;
    if allow_missing_fsverity {
        repo.set_insecure();
    }

    Ok(PullRepoResult {
        repo,
        entries,
        id,
        manifest_digest: pull_result.manifest_digest.to_string(),
    })
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_bootc_tag_for_manifest() {
        let digest = "sha256:abc123def456";
        let tag = bootc_tag_for_manifest(digest);
        assert_eq!(tag, "localhost/bootc-sha256:abc123def456");
        assert!(tag.starts_with(BOOTC_TAG_PREFIX));
    }
}