fix(errors)!: forbid interpolated details in wire-facing internal errors

Reviewed-on: #95

server/Cargo.lock

@@ -2,15 +2,6 @@
 # It is not intended for manual editing.
 version = 4
 
-[[package]]
-name = "addr2line"
-version = "0.25.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1b5d307320b3181d6d7954e663bd7c774a838b8220fe0593c86d9fb09f498b4b"
-dependencies = [
- "gimli",
-]
-
 [[package]]
 name = "adler2"
 version = "2.0.1"
@@ -1166,30 +1157,6 @@ dependencies = [
  "tower-service",
 ]
 
-[[package]]
-name = "backtrace"
-version = "0.3.76"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bb531853791a215d7c62a30daf0dde835f381ab5de4589cfe7c649d2cbe92bd6"
-dependencies = [
- "addr2line",
- "cfg-if",
- "libc",
- "miniz_oxide",
- "object",
- "rustc-demangle",
- "windows-link",
-]
-
-[[package]]
-name = "backtrace-ext"
-version = "0.2.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "537beee3be4a18fb023b570f80e3ae28003db9167a751266b259926e25539d50"
-dependencies = [
- "backtrace",
-]
-
 [[package]]
 name = "base16ct"
 version = "0.2.0"
@@ -2365,12 +2332,6 @@ dependencies = [
  "wasip3",
 ]
 
-[[package]]
-name = "gimli"
-version = "0.32.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e629b9b98ef3dd8afe6ca2bd0f89306cec16d43d907889945bc5d6687f2f13c7"
-
 [[package]]
 name = "glob"
 version = "0.3.3"
@@ -2828,12 +2789,6 @@ dependencies = [
  "serde",
 ]
 
-[[package]]
-name = "is_ci"
-version = "1.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7655c9839580ee829dfacba1d1278c2b7883e50a277ff7541299489d6bdfdc45"
-
 [[package]]
 name = "itertools"
 version = "0.10.5"
@@ -3169,18 +3124,9 @@ version = "7.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5f98efec8807c63c752b5bd61f862c165c115b0a35685bdcfd9238c7aeb592b7"
 dependencies = [
- "backtrace",
- "backtrace-ext",
  "cfg-if",
  "miette-derive",
- "owo-colors",
+ "unicode-width",
- "serde",
- "supports-color",
- "supports-hyperlinks",
- "supports-unicode",
- "terminal_size",
- "textwrap",
- "unicode-width 0.1.14",
 ]
 
 [[package]]
@@ -3402,15 +3348,6 @@ dependencies = [
  "smallvec",
 ]
 
-[[package]]
-name = "object"
-version = "0.37.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ff76201f031d8863c38aa7f905eca4f53abbfa15f609db4277d44cd8938f33fe"
-dependencies = [
- "memchr",
-]
-
 [[package]]
 name = "oid-registry"
 version = "0.8.1"
@@ -3438,12 +3375,6 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7c87def4c32ab89d880effc9e097653c8da5d6ef28e6b539d313baaacfbafcbe"
 
-[[package]]
-name = "owo-colors"
-version = "4.3.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d211803b9b6b570f68772237e415a029d5a50c65d382910b879fb19d3271f94d"
-
 [[package]]
 name = "parity-scale-codec"
 version = "3.7.5"
@@ -4247,12 +4178,6 @@ version = "1.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "48fd7bd8a6377e15ad9d42a8ec25371b94ddc67abe7c8b9127bec79bebaaae18"
 
-[[package]]
-name = "rustc-demangle"
-version = "0.1.27"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b50b8869d9fc858ce7266cce0194bd74df58b9d0e3f6df3a9fc8eb470d95c09d"
-
 [[package]]
 name = "rustc-hash"
 version = "2.1.2"
@@ -4892,27 +4817,6 @@ version = "2.6.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "13c2bddecc57b384dee18652358fb23172facb8a2c51ccc10d74c157bdea3292"
 
-[[package]]
-name = "supports-color"
-version = "3.0.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c64fc7232dd8d2e4ac5ce4ef302b1d81e0b80d055b9d77c7c4f51f6aa4c867d6"
-dependencies = [
- "is_ci",
-]
-
-[[package]]
-name = "supports-hyperlinks"
-version = "3.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e396b6523b11ccb83120b115a0b7366de372751aa6edf19844dfb13a6af97e91"
-
-[[package]]
-name = "supports-unicode"
-version = "3.0.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b7401a30af6cb5818bb64852270bb722533397edcfc7344954a38f420819ece2"
-
 [[package]]
 name = "syn"
 version = "1.0.109"
@@ -4986,16 +4890,6 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
-[[package]]
-name = "terminal_size"
-version = "0.4.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "230a1b821ccbd75b185820a1f1ff7b14d21da1e442e22c0863ea5f08771a8874"
-dependencies = [
- "rustix",
- "windows-sys 0.61.2",
-]
-
 [[package]]
 name = "test-log"
 version = "0.2.20"
@@ -5027,16 +4921,6 @@ dependencies = [
  "test-log-core",
 ]
 
-[[package]]
-name = "textwrap"
-version = "0.16.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c13547615a44dc9c452a8a534638acdf07120d4b6847c8178705da06306a3057"
-dependencies = [
- "unicode-linebreak",
- "unicode-width 0.2.2",
-]
-
 [[package]]
 name = "thiserror"
 version = "2.0.18"
@@ -5476,12 +5360,6 @@ version = "1.0.24"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e6e4313cd5fcd3dad5cafa179702e2b244f760991f45397d14d4ebf38247da75"
 
-[[package]]
-name = "unicode-linebreak"
-version = "0.1.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3b09c83c3c29d37506a3e260c08c03743a6bb66a9cd432c6934ab501a190571f"
-
 [[package]]
 name = "unicode-segmentation"
 version = "1.13.2"
@@ -5494,12 +5372,6 @@ version = "0.1.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7dd6e30e90baa6f72411720665d41d89b9a3d039dc45b8faea1ddd07f617f6af"
 
-[[package]]
-name = "unicode-width"
-version = "0.2.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b4ac048d71ede7ee76d585517add45da530660ef4390e49b098733c6e897f254"
-
 [[package]]
 name = "unicode-xid"
 version = "0.2.6"

server/Cargo.toml

@@ -15,7 +15,10 @@ k256 = { version = "0.13.4", features = ["ecdsa", "pkcs8"] }
 kameo = {git = "https://github.com/hdbg/kameo.git", rev = "805b417"}
 kameo_actors = {git = "https://github.com/hdbg/kameo.git", rev = "805b417"}
 hmac = "0.13.0"
-miette = { version = "7.6.0", features = ["fancy", "serde"] }
+# `derive` only: nothing renders a miette Report yet, so `fancy` would drag the
+# terminal-formatting stack (owo-colors, supports-color, textwrap, terminal_size)
+# into the headless daemon. A CLI that wants pretty output enables `fancy` itself.
+miette = "7.6.0"
 ml-dsa = { version = "0.1.0-rc.9", features = ["zeroize"] }
 mutants = "0.0.4"
 prost = "0.14.3"

server/crates/arbiter-client/src/auth.rs

@@ -23,6 +23,7 @@ use arbiter_proto::{
 use chrono::DateTime;
 
 #[derive(Debug, thiserror::Error)]
+#[non_exhaustive]
 pub enum AuthError {
     #[error("Server sent invalid auth challenge")]
     InvalidChallenge,

server/crates/arbiter-client/src/client.rs

@@ -17,6 +17,7 @@ use tokio_stream::wrappers::ReceiverStream;
 use tonic::transport::ClientTlsConfig;
 
 #[derive(Debug, thiserror::Error)]
+#[non_exhaustive]
 pub enum ArbiterClientError {
     #[error("Authentication error")]
     Authentication(#[from] AuthError),

server/crates/arbiter-client/src/storage.rs

@@ -4,6 +4,7 @@ use arbiter_proto::home_path;
 use std::path::{Path, PathBuf};
 
 #[derive(Debug, thiserror::Error)]
+#[non_exhaustive]
 pub enum StorageError {
     #[error("Invalid signing key length in storage: expected {expected} bytes, got {actual} bytes")]
     InvalidKeyLength { expected: usize, actual: usize },

server/crates/arbiter-client/src/transport.rs

@@ -11,6 +11,7 @@ pub fn next_request_id() -> i32 {
 }
 
 #[derive(Debug, thiserror::Error)]
+#[non_exhaustive]
 pub enum ClientSignError {
     #[error("Transport channel closed")]
     ChannelClosed,

server/crates/arbiter-proto/src/url.rs

@@ -30,6 +30,7 @@ impl Display for ArbiterUrl {
 }
 
 #[derive(Debug, thiserror::Error, miette::Diagnostic)]
+#[non_exhaustive]
 pub enum Error {
     #[error("Invalid URL scheme, expected '{ARBITER_URL_SCHEME}://'")]
     #[diagnostic(

server/crates/arbiter-server/src/crypto/integrity/v1.rs

@@ -13,6 +13,7 @@ use diesel_async::{AsyncConnection, RunQueryDsl};
 use hmac::Hmac;
 use kameo::{actor::ActorRef, error::SendError};
 use sha2::{Digest as _, Sha256};
+use tracing::error;
 
 #[derive(Debug, thiserror::Error)]
 pub enum Error {
@@ -121,7 +122,10 @@ pub async fn sign_entity<E: Integrable>(
             .await
             .map_err(|err| match err {
                 SendError::HandlerError(inner) => Error::Vault(inner),
-                _ => Error::VaultSend,
+                other => {
+                    error!(?other, "Vault unreachable while signing integrity envelope");
+                    Error::VaultSend
+                }
             })?;
 
     insert_into(integrity_envelope::table)
@@ -195,12 +199,18 @@ pub async fn verify_entity<E: Integrable>(
         Err(SendError::HandlerError(
             vault::Error::Sealed | vault::Error::KeyVersionMismatch { .. },
         )) => Ok(AttestationStatus::Unavailable),
-        Err(_) => Err(Error::VaultSend),
+        Err(other) => {
+            error!(?other, "Vault unreachable while verifying integrity envelope");
+            Err(Error::VaultSend)
+        }
     }
 }
 
 pub async fn is_signing_available(vault: &ActorRef<Vault>) -> Result<bool, Error> {
-    let state = vault.ask(GetState).await.map_err(|_| Error::VaultSend)?;
+    let state = vault.ask(GetState).await.map_err(|err| {
+        error!(?err, "Vault unreachable while querying signing availability");
+        Error::VaultSend
+    })?;
     Ok(matches!(state, vault::VaultState::Unsealed))
 }
 

server/crates/arbiter-server/src/peers/operator/auth/mod.rs

@@ -26,21 +26,22 @@ pub enum Error {
     UnregisteredPublicKey,
     InvalidChallengeSolution,
     InvalidBootstrapToken,
-    Internal { details: String },
+    /// Reaches the operator verbatim via `Status::internal`, so the payload is
+    /// `&'static str`: the type makes it impossible to interpolate an inner
+    /// error. Log the cause, send the constant.
+    Internal { details: &'static str },
     Transport,
 }
 
 impl Error {
-    fn internal(details: impl Into<String>) -> Self {
+    const fn internal(details: &'static str) -> Self {
-        Self::Internal {
+        Self::Internal { details }
-            details: details.into(),
-        }
     }
 }
 
 impl From<diesel::result::Error> for Error {
     fn from(e: diesel::result::Error) -> Self {
-        error!(?e, "Database error");
+        error!(error = %crate::utils::error_chain(&e), "Database error");
         Self::internal("Database error")
     }
 }

server/crates/arbiter-server/src/peers/operator/vault_gate/mod.rs

@@ -31,13 +31,11 @@ pub enum Error {
     #[error("State transition failed")]
     State,
 
+    /// Reaches the operator verbatim via `Status::internal`, so the payload is
+    /// `&'static str`: the type makes it impossible to interpolate an inner
+    /// error. Log the cause, send the constant.
     #[error("Internal error: {0}")]
-    Internal(String),
+    Internal(&'static str),
-}
-impl Error {
-    fn internal(message: impl Into<String>) -> Self {
-        Self::Internal(message.into())
-    }
 }
 
 pub struct HandshakeResponse {
@@ -179,7 +177,7 @@ impl VaultGate {
             }
             Err(err) => {
                 error!(?err, "Failed to send unseal request to vault");
-                Err(Error::internal("Vault actor error"))
+                Err(Error::Internal("Vault actor error"))
             }
         }
     }
@@ -221,7 +219,7 @@ impl VaultGate {
             }
             Err(err) => {
                 error!(?err, "Failed to send bootstrap request to vault");
-                Err(Error::internal("Vault error"))
+                Err(Error::Internal("Vault error"))
             }
         }
     }
@@ -233,7 +231,10 @@ impl VaultGate {
             .vault
             .ask(GetState {})
             .await
-            .map_err(|_| Error::internal("failed to query vault"))?;
+            .map_err(|err| {
+                error!(?err, "Failed to query vault state");
+                Error::Internal("failed to query vault")
+            })?;
 
         Ok(answer)
     }
@@ -252,7 +253,10 @@ impl Message<events::Bootstrapped> for VaultGate {
                 .db
                 .get()
                 .await
-                .map_err(|_| Error::internal("DB unavailable"))?;
+                .map_err(|err| {
+                    error!(error = %crate::utils::error_chain(&err), "DB unavailable on bootstrap");
+                    Error::Internal("DB unavailable")
+                })?;
             integrity::sign_entity(
                 &mut conn,
                 &self.actors.vault,
@@ -260,9 +264,12 @@ impl Message<events::Bootstrapped> for VaultGate {
                 self.auth_creds.id,
             )
             .await
-            .map_err(|e| {
+            .map_err(|err| {
-                error!(?e, "Failed to sign integrity envelope on bootstrap");
+                error!(
-                Error::internal("Integrity sign failed")
+                    error = %crate::utils::error_chain(&err),
+                    "Failed to sign integrity envelope on bootstrap"
+                );
+                Error::Internal("Integrity sign failed")
             })?;
             Ok(())
         }

server/crates/arbiter-server/src/utils.rs

@@ -14,3 +14,47 @@ impl<F: FnOnce()> Drop for DeferClosure<F> {
 pub fn defer<F: FnOnce()>(f: F) -> impl Drop + Sized {
     DeferClosure { f: Some(f) }
 }
+
+/// Renders an error together with its full `source` chain as `outer: inner: root`.
+///
+/// Error variants in this crate deliberately keep `Display` terse so that no
+/// internal detail can leak across the gRPC boundary. That same terseness would
+/// hide the cause in the logs, so use this for `tracing` fields, never in a
+/// wire payload.
+pub fn error_chain(err: &dyn core::error::Error) -> String {
+    let mut out = err.to_string();
+    let mut current = err.source();
+    while let Some(source) = current {
+        out.push_str(": ");
+        out.push_str(&source.to_string());
+        current = source.source();
+    }
+    out
+}
+
+#[cfg(test)]
+mod tests {
+    use super::error_chain;
+
+    #[derive(Debug, thiserror::Error)]
+    #[error("root")]
+    struct Root;
+
+    #[derive(Debug, thiserror::Error)]
+    #[error("middle")]
+    struct Middle(#[source] Root);
+
+    #[derive(Debug, thiserror::Error)]
+    #[error("outer")]
+    struct Outer(#[source] Middle);
+
+    #[test]
+    fn walks_the_whole_source_chain() {
+        assert_eq!(error_chain(&Root), "root", "a leaf error renders alone");
+        assert_eq!(
+            error_chain(&Outer(Middle(Root))),
+            "outer: middle: root",
+            "every source link must appear, in order"
+        );
+    }
+}