image-rs: Support simple signing with X-R-S-S

Support getting simple signing signatures from
registry that supports X-R-S-S extension.

Refactor into separate tests for XRSS and others.

Fixes: confidential-containers#12

Signed-off-by: Matthew Arnold <mattarno@uk.ibm.com>

.github/workflows/image_rs_build.yml

@@ -74,6 +74,7 @@ jobs:
           cargo clippy -p image-rs --all-targets --features=kata-cc-native-tls --no-default-features -- -D warnings
           cargo clippy -p image-rs --all-targets --features=enclave-cc-eaakbc-native-tls --no-default-features -- -D warnings
           cargo clippy -p image-rs --all-targets --features=enclave-cc-cckbc-native-tls --no-default-features -- -D warnings
+          cargo clippy -p image-rs --all-targets --features=kata-cc-native-tls,signature-simple-xrss --no-default-features -- -D warnings
 
       - name: Run cargo build
         uses: actions-rs/cargo@v1
@@ -100,3 +101,9 @@ jobs:
       - name: Run cargo test - kata-cc (native-tls version) with keywrap-ttrpc (default) + keywrap-jwe
         run: |
           sudo -E PATH=$PATH -s cargo test -p image-rs --no-default-features --features=kata-cc-native-tls,keywrap-jwe
+
+      - name: Run cargo test - kata-cc (native-tls version) with keywrap-ttrpc (default) + keywrap-jwe and with signatures from XRSS registry extension
+        env:
+          AUTH_PASSWORD: ${{ secrets.SH_ICR_API_KEY }}
+        run: |
+          sudo -E PATH=$PATH -s cargo test -p image-rs --no-default-features --features=kata-cc-native-tls,keywrap-jwe,signature-simple-xrss

image-rs/Cargo.toml

@@ -32,6 +32,7 @@ oci-spec = "0.6.2"
 ocicrypt-rs = { path = "../ocicrypt-rs", default-features = false, features = ["async-io"], optional = true }
 prost = { workspace = true, optional = true }
 protobuf = { workspace = true, optional = true }
+reqwest = { workspace = true, features = ["json"], optional = true }
 sequoia-openpgp = { version = "1.7.0", default-features = false, features = ["compression", "crypto-rust", "allow-experimental-crypto", "allow-variable-time-crypto"], optional = true }
 serde = { workspace = true, features = ["serde_derive", "rc"] }
 serde_json.workspace = true
@@ -111,6 +112,7 @@ signature-cosign-native = ["signature-cosign", "sigstore/cosign-native-tls"]
 oci-distribution-rustls = ["oci-distribution/rustls-tls"]
 oci-distribution-native = ["oci-distribution/native-tls"]
 
+signature-simple-xrss = ["signature-simple", "dep:reqwest"]
 signature-simple = ["signature", "sequoia-openpgp", "serde_yaml"]
 
 snapshot-overlayfs = ["nix"]

image-rs/src/signature/mechanism/simple/mod.rs

@@ -10,10 +10,15 @@ use serde::*;
 use strum_macros::Display;
 use strum_macros::EnumString;
 
+#[cfg(feature = "signature-simple")]
+use base64::Engine;
+
 #[cfg(feature = "signature-simple")]
 mod sigstore;
 #[cfg(feature = "signature-simple")]
 mod verify;
+#[cfg(feature = "signature-simple-xrss")]
+mod xrss;
 
 use crate::signature::{image::Image, mechanism::Paths, policy::ref_match::PolicyReqMatchType};
 
@@ -71,9 +76,16 @@ impl SignScheme for SimpleParameters {
     async fn init(&mut self, config: &Paths) -> Result<()> {
         prepare_runtime_dirs(crate::config::SIG_STORE_CONFIG_DIR).await?;
         self.initialize_sigstore_config().await?;
-        let sig_store_config_file = crate::resource::get_resource(&config.sigstore_config).await?;
+        let sig_store_config_file = crate::resource::get_resource(&config.sigstore_config).await;
+
+        #[cfg(feature = "signature-simple-xrss")]
+        if sig_store_config_file.is_err() {
+            // When using xrss extension a sigstore config file is optional
+            return Ok(());
+        }
+
         let sig_store_config_file =
-            serde_yaml::from_slice::<sigstore::SigstoreConfig>(&sig_store_config_file)?;
+            serde_yaml::from_slice::<sigstore::SigstoreConfig>(&sig_store_config_file?)?;
         self.sig_store_config_file
             .update_self(sig_store_config_file)?;
         Ok(())
@@ -86,7 +98,6 @@ impl SignScheme for SimpleParameters {
 
     #[cfg(feature = "signature-simple")]
     async fn allows_image(&self, image: &mut Image, _auth: &RegistryAuth) -> Result<()> {
-        use base64::Engine;
         // FIXME: only support "GPGKeys" type now.
         //
         // refer to https://github.com/confidential-containers/image-rs/issues/14
@@ -108,7 +119,7 @@ impl SignScheme for SimpleParameters {
             }
         };
 
-        let sigs = self.get_signatures(image).await?;
+        let sigs = self.get_signatures(image, _auth).await?;
         let mut reject_reasons: Vec<anyhow::Error> = Vec::new();
 
         for sig in sigs.iter() {
@@ -182,22 +193,19 @@ impl SimpleParameters {
     /// Set the content of sigstore config with files in
     /// [`crate::config::SIG_STORE_CONFIG_DIR`]
     pub async fn initialize_sigstore_config(&mut self) -> Result<()> {
-        // If the registry support `X-Registry-Supports-Signatures` API extension,
-        // try to get signatures from the registry first.
-        // Else, get signatures from "sigstore" according to the sigstore config file.
-        // (https://github.com/containers/image/issues/384)
-        //
-        // TODO: Add get signatures from registry X-R-S-S API extension.
-        //
-        // issue: https://github.com/confidential-containers/image-rs/issues/12
         let sigstore_config =
             sigstore::SigstoreConfig::new_from_configs(crate::config::SIG_STORE_CONFIG_DIR).await?;
         self.sig_store_config_file.update_self(sigstore_config)?;
 
         Ok(())
     }
 
-    pub async fn get_signatures(&self, image: &Image) -> Result<Vec<Vec<u8>>> {
+    pub async fn get_signatures(
+        &self,
+        image: &Image,
+        _auth: &RegistryAuth,
+    ) -> Result<Vec<Vec<u8>>> {
+        let mut sigs: Vec<Vec<u8>> = Vec::new();
         // Get image digest (manifest digest)
         let image_digest = if !image.manifest_digest.is_empty() {
             image.manifest_digest.clone()
@@ -207,6 +215,22 @@ impl SimpleParameters {
             bail!("Missing image digest");
         };
 
+        #[cfg(feature = "signature-simple-xrss")]
+        {
+            let registry_client = xrss::RegistryClient::new();
+            let mut registry_sigs = registry_client
+                .get_signatures_from_registry(image, &image_digest, _auth)
+                .await?;
+            sigs.append(&mut registry_sigs);
+            if self.sig_store_config_file == sigstore::SigstoreConfig::default() {
+                if sigs.is_empty() {
+                    bail!("Missing sigstore config file and no signatures in registry");
+                }
+
+                return Ok(sigs);
+            }
+        }
+
         // Format the sigstore name: `image-repository@digest-algorithm=digest-value`.
         let sigstore_name = sigstore::format_sigstore_name(&image.reference, image_digest);
 
@@ -219,7 +243,8 @@ impl SimpleParameters {
         let sigstore_uri = url::Url::parse(&sigstore)
             .map_err(|e| anyhow!("Failed to parse sigstore_uri: {:?}", e))?;
 
-        let sigs = sigstore::get_sigs_from_specific_sigstore(sigstore_uri).await?;
+        let mut sigstore_sigs = sigstore::get_sigs_from_specific_sigstore(sigstore_uri).await?;
+        sigs.append(&mut sigstore_sigs);
 
         Ok(sigs)
     }