Verify plugin signatures

crates/ely_app/Cargo.toml

@@ -7,6 +7,7 @@ rust-version.workspace = true
 
 [dependencies]
 directories.workspace = true
+ed25519-dalek.workspace = true
 ely_browser_core = { path = "../ely_browser_core" }
 ely_design_system = { path = "../ely_design_system" }
 ely_domain = { path = "../ely_domain" }

crates/ely_app/src/services/mod.rs

@@ -2,3 +2,7 @@ pub mod download_checksums;
 pub mod download_files;
 pub mod plugin_package_store;
 pub mod plugin_packages;
+pub mod plugin_signatures;
+
+#[cfg(test)]
+mod plugin_package_fixtures;

crates/ely_app/src/services/plugin_package_fixtures.rs

@@ -0,0 +1,93 @@
+use std::{
+    error::Error,
+    fs,
+    path::{Path, PathBuf},
+};
+
+use ed25519_dalek::{Signer, SigningKey};
+use ely_domain::PluginManifest;
+use sha2::{Digest, Sha256};
+
+use super::plugin_signatures::signing_payload;
+
+const KEY_ID: &str = "elydora-alpha-plugins";
+const TEST_SIGNING_KEY: [u8; 32] = [9; 32];
+
+pub(crate) fn write_signed_package(
+    root: &Path,
+    name: &str,
+    component: &[u8],
+) -> Result<PathBuf, Box<dyn Error>> {
+    let package = root.join(format!("{name}.rplug"));
+    fs::create_dir_all(package.join("signatures"))?;
+    fs::write(package.join("component.wasm"), component)?;
+    sign_package_in_place(package.as_path(), name)?;
+    Ok(package)
+}
+
+pub(crate) fn sign_package_in_place(package: &Path, name: &str) -> Result<(), Box<dyn Error>> {
+    fs::create_dir_all(package.join("signatures"))?;
+
+    let signing_key = SigningKey::from_bytes(&TEST_SIGNING_KEY);
+    let public_key = hex_bytes(signing_key.verifying_key().to_bytes().as_slice());
+    let component = fs::read(package.join("component.wasm"))?;
+    let checksum = format!("{:x}", Sha256::digest(component.as_slice()));
+    let placeholder_signature = "0".repeat(128);
+
+    fs::write(
+        package.join("plugin.toml"),
+        manifest_toml(name, checksum.as_str(), public_key.as_str(), placeholder_signature.as_str()),
+    )?;
+
+    let manifest_text = fs::read_to_string(package.join("plugin.toml"))?;
+    let manifest = PluginManifest::from_toml(manifest_text.as_str())?;
+    let payload = signing_payload(package, &manifest)?;
+    let signature = signing_key.sign(payload.as_slice());
+    let signature = hex_bytes(signature.to_bytes().as_slice());
+
+    fs::write(package.join("signatures").join("ed25519.sig"), signature.as_str())?;
+    fs::write(
+        package.join("plugin.toml"),
+        manifest_toml(name, checksum.as_str(), public_key.as_str(), signature.as_str()),
+    )?;
+
+    Ok(())
+}
+
+fn manifest_toml(name: &str, checksum: &str, public_key: &str, signature: &str) -> String {
+    format!(
+        r#"
+id = "com.elydora.{name}"
+name = "Verified Plugin"
+description = "Exports verified content."
+author = "Elydora"
+homepage = "https://elydora.com/plugins/{name}"
+permissions = ["page:metadata"]
+contributes = ["command-bar-command"]
+min_ely_build = "0.1.0"
+checksum = "{checksum}"
+
+[signature]
+algorithm = "ed25519"
+key_id = "{KEY_ID}"
+public_key = "{public_key}"
+value = "{signature}"
+"#
+    )
+}
+
+fn hex_bytes(bytes: &[u8]) -> String {
+    let mut encoded = String::with_capacity(bytes.len() * 2);
+    for byte in bytes {
+        encoded.push(hex_char(byte >> 4));
+        encoded.push(hex_char(byte & 0x0f));
+    }
+    encoded
+}
+
+fn hex_char(value: u8) -> char {
+    match value {
+        0..=9 => (b'0' + value) as char,
+        _ => (b'a' + value - 10) as char,
+    }
+}

crates/ely_app/src/services/plugin_package_store.rs

@@ -261,9 +261,8 @@ mod tests {
         time::{SystemTime, UNIX_EPOCH},
     };
 
-    use sha2::{Digest, Sha256};
-
     use super::{PluginPackageStore, PluginPackageStoreError};
+    use crate::services::plugin_package_fixtures::write_signed_package;
     use crate::services::plugin_packages::PluginPackageReader;
 
     #[test]
@@ -324,43 +323,7 @@ mod tests {
     }
 
     fn write_package(root: &Path, name: &str, component: &[u8]) -> Result<PathBuf, Box<dyn Error>> {
-        let package = root.join(format!("{name}.rplug"));
-        fs::create_dir_all(package.join("signatures"))?;
-        fs::write(package.join("component.wasm"), component)?;
-
-        let checksum = sha256_bytes(component);
-        let signature = "b".repeat(128);
-        fs::write(package.join("signatures").join("ed25519.sig"), &signature)?;
-        fs::write(
-            package.join("plugin.toml"),
-            manifest_toml(name, checksum.as_str(), signature.as_str()),
-        )?;
-
-        Ok(package)
-    }
-
-    fn manifest_toml(name: &str, checksum: &str, signature: &str) -> String {
-        format!(
-            r#"
-id = "com.elydora.{name}"
-name = "Verified Plugin"
-description = "Exports verified content."
-author = "Elydora"
-homepage = "https://elydora.com/plugins/{name}"
-permissions = ["page:metadata"]
-contributes = ["command-bar-command"]
-min_ely_build = "0.1.0"
-checksum = "{checksum}"
-
-[signature]
-algorithm = "ed25519"
-value = "{signature}"
-"#
-        )
-    }
-
-    fn sha256_bytes(bytes: &[u8]) -> String {
-        format!("{:x}", Sha256::digest(bytes))
+        write_signed_package(root, name, component)
     }
 
     struct TempTree {

crates/ely_app/src/services/plugin_packages.rs

@@ -9,6 +9,8 @@ use ely_domain::PluginManifest;
 use sha2::{Digest, Sha256};
 use thiserror::Error;
 
+use super::plugin_signatures::{PluginSignatureVerificationError, PluginSignatureVerifier};
+
 #[derive(Clone, Debug, Eq, PartialEq)]
 pub struct VerifiedPluginPackage {
     source_path: PathBuf,
@@ -48,6 +50,9 @@ pub enum PluginPackageError {
     #[error("plugin package signature mismatch for signatures/ed25519.sig")]
     SignatureMismatch,
 
+    #[error(transparent)]
+    SignatureVerification(#[from] PluginSignatureVerificationError),
+
     #[error(transparent)]
     Manifest(#[from] ely_domain::DomainError),
 }
@@ -78,6 +83,7 @@ impl PluginPackageReader {
         if signature.trim().to_ascii_lowercase() != manifest.signature().value() {
             return Err(PluginPackageError::SignatureMismatch);
         }
+        PluginSignatureVerifier::verify(path, &manifest)?;
 
         let package_hash = sha256_directory(path)?;
         Ok(VerifiedPluginPackage::new(path.to_path_buf(), manifest, package_hash))
@@ -304,9 +310,8 @@ mod tests {
         time::{SystemTime, UNIX_EPOCH},
     };
 
-    use sha2::{Digest, Sha256};
-
     use super::PluginPackageReader;
+    use crate::services::plugin_package_fixtures::{sign_package_in_place, write_signed_package};
 
     #[test]
     fn reads_verified_directory_package() -> Result<(), Box<dyn Error>> {
@@ -346,6 +351,19 @@ mod tests {
         Ok(())
     }
 
+    #[test]
+    fn rejects_package_signature_verification_failure() -> Result<(), Box<dyn Error>> {
+        let package = write_package("verification", b"wasm component")?;
+        fs::write(package.join("README.md"), "unsigned package metadata")?;
+
+        let error = PluginPackageReader::read_directory_package(&package)
+            .err()
+            .ok_or_else(|| std::io::Error::other("package read succeeded"))?;
+
+        assert!(matches!(error, super::PluginPackageError::SignatureVerification(_)));
+        Ok(())
+    }
+
     #[test]
     fn rejects_non_package_directory() -> Result<(), Box<dyn Error>> {
         let package = temp_root()?.join("invalid");
@@ -365,6 +383,7 @@ mod tests {
         let first_hash =
             PluginPackageReader::read_directory_package(&package)?.package_hash().to_string();
         fs::write(package.join("README.md"), "updated package metadata")?;
+        sign_package_in_place(package.as_path(), "package-hash")?;
 
         let second_hash =
             PluginPackageReader::read_directory_package(&package)?.package_hash().to_string();
@@ -374,43 +393,7 @@ mod tests {
     }
 
     fn write_package(name: &str, component: &[u8]) -> Result<PathBuf, Box<dyn Error>> {
-        let package = temp_root()?.join(format!("{name}.rplug"));
-        fs::create_dir_all(package.join("signatures"))?;
-        fs::write(package.join("component.wasm"), component)?;
-
-        let checksum = sha256_bytes(component);
-        let signature = "b".repeat(128);
-        fs::write(package.join("signatures").join("ed25519.sig"), &signature)?;
-        fs::write(
-            package.join("plugin.toml"),
-            manifest_toml(name, checksum.as_str(), signature.as_str()),
-        )?;
-
-        Ok(package)
-    }
-
-    fn manifest_toml(name: &str, checksum: &str, signature: &str) -> String {
-        format!(
-            r#"
-id = "com.elydora.{name}"
-name = "Verified Plugin"
-description = "Exports verified content."
-author = "Elydora"
-homepage = "https://elydora.com/plugins/{name}"
-permissions = ["page:metadata"]
-contributes = ["command-bar-command"]
-min_ely_build = "0.1.0"
-checksum = "{checksum}"
-
-[signature]
-algorithm = "ed25519"
-value = "{signature}"
-"#
-        )
-    }
-
-    fn sha256_bytes(bytes: &[u8]) -> String {
-        format!("{:x}", Sha256::digest(bytes))
+        write_signed_package(temp_root()?.as_path(), name, component)
     }
 
     fn temp_root() -> Result<PathBuf, Box<dyn Error>> {

crates/ely_app/src/services/plugin_signatures.rs

@@ -0,0 +1,306 @@
+use std::{
+    ffi::OsStr,
+    fs,
+    io::{self, Read},
+    path::{Component, Path, PathBuf},
+};
+
+use ed25519_dalek::{Signature, Verifier, VerifyingKey};
+use ely_domain::PluginManifest;
+use sha2::{Digest, Sha256};
+use thiserror::Error;
+
+#[derive(Debug, Error)]
+pub enum PluginSignatureVerificationError {
+    #[error("plugin signature public key is invalid for key {key_id}")]
+    InvalidPublicKey { key_id: String },
+
+    #[error("plugin signature value is invalid for key {key_id}")]
+    InvalidSignature { key_id: String },
+
+    #[error("plugin signature verification failed for key {key_id}")]
+    VerificationFailed { key_id: String },
+
+    #[error("failed to read plugin package entry {entry}: {path}")]
+    ReadFailed { entry: &'static str, path: PathBuf, source: io::Error },
+
+    #[error("plugin package entry name must be valid utf-8: {path}")]
+    InvalidEntryName { path: PathBuf },
+
+    #[error("plugin package entry cannot be signed through a symlink: {path}")]
+    SymlinkEntry { path: PathBuf },
+
+    #[error("plugin package entry type is unsupported: {path}")]
+    UnsupportedEntry { path: PathBuf },
+}
+
+pub struct PluginSignatureVerifier;
+
+impl PluginSignatureVerifier {
+    pub fn verify(
+        package_root: &Path,
+        manifest: &PluginManifest,
+    ) -> Result<(), PluginSignatureVerificationError> {
+        let key_id = manifest.signature().key_id().to_string();
+        let public_key =
+            decode_hex_array::<32>(manifest.signature().public_key()).ok_or_else(|| {
+                PluginSignatureVerificationError::InvalidPublicKey { key_id: key_id.clone() }
+            })?;
+        let signature = decode_hex_array::<64>(manifest.signature().value()).ok_or_else(|| {
+            PluginSignatureVerificationError::InvalidSignature { key_id: key_id.clone() }
+        })?;
+        let key = VerifyingKey::from_bytes(&public_key).map_err(|_| {
+            PluginSignatureVerificationError::InvalidPublicKey { key_id: key_id.clone() }
+        })?;
+        let signature = Signature::from_bytes(&signature);
+        let payload = signing_payload(package_root, manifest)?;
+
+        key.verify(payload.as_slice(), &signature)
+            .map_err(|_| PluginSignatureVerificationError::VerificationFailed { key_id })
+    }
+}
+
+pub(crate) fn signing_payload(
+    package_root: &Path,
+    manifest: &PluginManifest,
+) -> Result<Vec<u8>, PluginSignatureVerificationError> {
+    let mut payload = Vec::new();
+    append_field(&mut payload, "format", "ely.rplug.signature.v1");
+    append_field(&mut payload, "id", manifest.id().as_str());
+    append_field(&mut payload, "name", manifest.name());
+    append_field(&mut payload, "description", manifest.description());
+    append_field(&mut payload, "author", manifest.author());
+    append_field(&mut payload, "homepage", manifest.homepage());
+    append_list(
+        &mut payload,
+        "permissions",
+        manifest.permissions().iter().map(|permission| permission.as_str()),
+    );
+    append_list(
+        &mut payload,
+        "contributes",
+        manifest.contributes().iter().map(|contribution| contribution.as_str()),
+    );
+    append_field(&mut payload, "min_ely_build", manifest.min_ely_build().to_string().as_str());
+    append_field(&mut payload, "checksum", manifest.checksum());
+    append_field(&mut payload, "signature_algorithm", manifest.signature().algorithm().as_str());
+    append_field(&mut payload, "signature_key_id", manifest.signature().key_id());
+    append_field(&mut payload, "signature_public_key", manifest.signature().public_key());
+    append_field(&mut payload, "package_files_sha256", package_files_hash(package_root)?.as_str());
+    Ok(payload)
+}
+
+fn package_files_hash(package_root: &Path) -> Result<String, PluginSignatureVerificationError> {
+    let mut entries = Vec::new();
+    collect_signed_entries(package_root, Path::new(""), &mut entries)?;
+    entries.sort_by(|left, right| left.relative_path.cmp(&right.relative_path));
+
+    let mut hasher = Sha256::new();
+    for entry in entries {
+        let relative_path = canonical_relative_path(entry.relative_path.as_path())?;
+        match entry.kind {
+            SignedEntryKind::Directory => {
+                hasher.update(b"dir\0");
+                hasher.update(relative_path.as_bytes());
+                hasher.update(b"\0");
+            }
+            SignedEntryKind::File => {
+                hasher.update(b"file\0");
+                hasher.update(relative_path.as_bytes());
+                hasher.update(b"\0");
+                hash_file_content(entry.absolute_path.as_path(), &mut hasher)?;
+            }
+        }
+    }
+
+    Ok(format!("{:x}", hasher.finalize()))
+}
+
+fn collect_signed_entries(
+    root: &Path,
+    relative_dir: &Path,
+    entries: &mut Vec<SignedEntry>,
+) -> Result<(), PluginSignatureVerificationError> {
+    let absolute_dir = root.join(relative_dir);
+    for entry in fs::read_dir(absolute_dir.as_path()).map_err(|source| {
+        PluginSignatureVerificationError::ReadFailed {
+            entry: "package",
+            path: absolute_dir.clone(),
+            source,
+        }
+    })? {
+        let entry = entry.map_err(|source| PluginSignatureVerificationError::ReadFailed {
+            entry: "package",
+            path: absolute_dir.clone(),
+            source,
+        })?;
+        let absolute_path = entry.path();
+        let relative_path = relative_dir.join(entry.file_name());
+        if excluded_signature_entry(relative_path.as_path()) {
+            continue;
+        }
+
+        let metadata = fs::symlink_metadata(absolute_path.as_path()).map_err(|source| {
+            PluginSignatureVerificationError::ReadFailed {
+                entry: "package",
+                path: absolute_path.clone(),
+                source,
+            }
+        })?;
+        let file_type = metadata.file_type();
+
+        if file_type.is_symlink() {
+            return Err(PluginSignatureVerificationError::SymlinkEntry { path: absolute_path });
+        }
+        if file_type.is_dir() {
+            entries.push(SignedEntry::new(
+                relative_path.clone(),
+                absolute_path,
+                SignedEntryKind::Directory,
+            ));
+            collect_signed_entries(root, relative_path.as_path(), entries)?;
+            continue;
+        }
+        if file_type.is_file() {
+            entries.push(SignedEntry::new(relative_path, absolute_path, SignedEntryKind::File));
+            continue;
+        }
+
+        return Err(PluginSignatureVerificationError::UnsupportedEntry { path: absolute_path });
+    }
+
+    Ok(())
+}
+
+fn excluded_signature_entry(path: &Path) -> bool {
+    let mut components = path.components();
+    match components.next() {
+        Some(Component::Normal(value)) if value == OsStr::new("plugin.toml") => true,
+        Some(Component::Normal(value)) if value == OsStr::new("signatures") => true,
+        _ => false,
+    }
+}
+
+fn canonical_relative_path(path: &Path) -> Result<String, PluginSignatureVerificationError> {
+    let mut parts = Vec::new();
+    for component in path.components() {
+        let Component::Normal(value) = component else {
+            return Err(PluginSignatureVerificationError::InvalidEntryName {
+                path: path.to_path_buf(),
+            });
+        };
+        parts.push(utf8_entry_name(value, path)?);
+    }
+    Ok(parts.join("/"))
+}
+
+fn utf8_entry_name<'a>(
+    value: &'a OsStr,
+    path: &Path,
+) -> Result<&'a str, PluginSignatureVerificationError> {
+    value.to_str().ok_or_else(|| PluginSignatureVerificationError::InvalidEntryName {
+        path: path.to_path_buf(),
+    })
+}
+
+fn hash_file_content(
+    path: &Path,
+    hasher: &mut Sha256,
+) -> Result<(), PluginSignatureVerificationError> {
+    let mut file =
+        fs::File::open(path).map_err(|source| PluginSignatureVerificationError::ReadFailed {
+            entry: "package",
+            path: path.to_path_buf(),
+            source,
+        })?;
+    let metadata =
+        file.metadata().map_err(|source| PluginSignatureVerificationError::ReadFailed {
+            entry: "package",
+            path: path.to_path_buf(),
+            source,
+        })?;
+    hasher.update(metadata.len().to_le_bytes());
+    hasher.update(b"\0");
+    let mut buffer = [0_u8; 8192];
+
+    loop {
+        let read = file.read(&mut buffer).map_err(|source| {
+            PluginSignatureVerificationError::ReadFailed {
+                entry: "package",
+                path: path.to_path_buf(),
+                source,
+            }
+        })?;
+        if read == 0 {
+            break;
+        }
+        hasher.update(&buffer[..read]);
+    }
+
+    Ok(())
+}
+
+fn append_field(payload: &mut Vec<u8>, name: &str, value: &str) {
+    payload.extend_from_slice(name.as_bytes());
+    payload.extend_from_slice(b"\0");
+    payload.extend_from_slice(value.len().to_string().as_bytes());
+    payload.extend_from_slice(b"\0");
+    payload.extend_from_slice(value.as_bytes());
+    payload.extend_from_slice(b"\0");
+}
+
+fn append_list<'a>(payload: &mut Vec<u8>, name: &str, values: impl Iterator<Item = &'a str>) {
+    let values = values.collect::<Vec<_>>();
+    payload.extend_from_slice(name.as_bytes());
+    payload.extend_from_slice(b"\0");
+    payload.extend_from_slice(values.len().to_string().as_bytes());
+    payload.extend_from_slice(b"\0");
+    for value in values {
+        payload.extend_from_slice(value.len().to_string().as_bytes());
+        payload.extend_from_slice(b"\0");
+        payload.extend_from_slice(value.as_bytes());
+        payload.extend_from_slice(b"\0");
+    }
+}
+
+fn decode_hex_array<const N: usize>(value: &str) -> Option<[u8; N]> {
+    if value.len() != N * 2 {
+        return None;
+    }
+
+    let mut output = [0_u8; N];
+    for (index, chunk) in value.as_bytes().chunks_exact(2).enumerate() {
+        let high = hex_nibble(chunk[0])?;
+        let low = hex_nibble(chunk[1])?;
+        output[index] = (high << 4) | low;
+    }
+    Some(output)
+}
+
+fn hex_nibble(value: u8) -> Option<u8> {
+    match value {
+        b'0'..=b'9' => Some(value - b'0'),
+        b'a'..=b'f' => Some(value - b'a' + 10),
+        b'A'..=b'F' => Some(value - b'A' + 10),
+        _ => None,
+    }
+}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+struct SignedEntry {
+    relative_path: PathBuf,
+    absolute_path: PathBuf,
+    kind: SignedEntryKind,
+}
+
+impl SignedEntry {
+    fn new(relative_path: PathBuf, absolute_path: PathBuf, kind: SignedEntryKind) -> Self {
+        Self { relative_path, absolute_path, kind }
+    }
+}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+enum SignedEntryKind {
+    Directory,
+    File,
+}