feat(security): harden gateway request and runtime controls

2026-10-04 08:27:46 +08:00 · 2026-07-12 14:10:54 +08:00
parent bc1da3bf3f
commit 7f61bb43c7
19 changed files with 975 additions and 340 deletions
@@ -652,7 +652,9 @@ pub(super) async fn extract_admin_provider_oauth_batch_error_detail(
    response: Response<Body>,
 ) -> String {
    let status = response.status();
-    let raw_body = to_bytes(response.into_body(), usize::MAX).await.ok();
+    let raw_body = to_bytes(response.into_body(), crate::MAX_ERROR_BODY_BYTES)
+        .await
+        .ok();
    if let Some(raw_body) = raw_body {
        if let Ok(value) = serde_json::from_slice::<serde_json::Value>(&raw_body) {
            if let Some(detail) = value.get("detail").and_then(serde_json::Value::as_str) {
@@ -1704,9 +1704,12 @@ async fn provider_query_finalize_kiro_result(
    let Some(outcome) = maybe_build_sync_finalize_outcome(trace_id, &decision, &payload)? else {
        return Ok(None);
    };
-    let bytes = to_bytes(outcome.response.into_body(), usize::MAX)
-        .await
-        .map_err(|err| GatewayError::Internal(err.to_string()))?;
+    let bytes = to_bytes(
+        outcome.response.into_body(),
+        crate::headers::max_internal_buffered_body_bytes(),
+    )
+    .await
+    .map_err(|err| GatewayError::Internal(err.to_string()))?;
    serde_json::from_slice::<Value>(&bytes)
        .map(Some)
        .map_err(|err| GatewayError::Internal(err.to_string()))
@@ -1926,9 +1929,12 @@ async fn provider_query_finalize_windsurf_result(
    let Some(outcome) = maybe_build_sync_finalize_outcome(trace_id, &decision, &payload)? else {
        return Ok(None);
    };
-    let bytes = to_bytes(outcome.response.into_body(), usize::MAX)
-        .await
-        .map_err(|err| GatewayError::Internal(err.to_string()))?;
+    let bytes = to_bytes(
+        outcome.response.into_body(),
+        crate::headers::max_internal_buffered_body_bytes(),
+    )
+    .await
+    .map_err(|err| GatewayError::Internal(err.to_string()))?;
    serde_json::from_slice::<Value>(&bytes)
        .map(Some)
        .map_err(|err| GatewayError::Internal(err.to_string()))
@@ -2044,9 +2050,12 @@ async fn provider_query_finalize_openai_image_result(
    let Some(outcome) = maybe_build_sync_finalize_outcome(trace_id, &decision, &payload)? else {
        return Ok(None);
    };
-    let bytes = to_bytes(outcome.response.into_body(), usize::MAX)
-        .await
-        .map_err(|err| GatewayError::Internal(err.to_string()))?;
+    let bytes = to_bytes(
+        outcome.response.into_body(),
+        crate::headers::max_internal_buffered_body_bytes(),
+    )
+    .await
+    .map_err(|err| GatewayError::Internal(err.to_string()))?;
    serde_json::from_slice::<Value>(&bytes)
        .map(Some)
        .map_err(|err| GatewayError::Internal(err.to_string()))
@@ -2412,9 +2421,12 @@ async fn provider_query_finalize_antigravity_result(
    let Some(outcome) = maybe_build_sync_finalize_outcome(trace_id, &decision, &payload)? else {
        return Ok(None);
    };
-    let bytes = to_bytes(outcome.response.into_body(), usize::MAX)
-        .await
-        .map_err(|err| GatewayError::Internal(err.to_string()))?;
+    let bytes = to_bytes(
+        outcome.response.into_body(),
+        crate::headers::max_internal_buffered_body_bytes(),
+    )
+    .await
+    .map_err(|err| GatewayError::Internal(err.to_string()))?;
    serde_json::from_slice::<Value>(&bytes)
        .map(Some)
        .map_err(|err| GatewayError::Internal(err.to_string()))
@@ -3794,9 +3806,12 @@ pub(crate) async fn build_admin_provider_query_test_model_local_response(
    if !response.status().is_success() {
        return Ok(response);
    }
-    let body = to_bytes(response.into_body(), usize::MAX)
-        .await
-        .map_err(|err| GatewayError::Internal(err.to_string()))?;
+    let body = to_bytes(
+        response.into_body(),
+        crate::headers::max_internal_buffered_body_bytes(),
+    )
+    .await
+    .map_err(|err| GatewayError::Internal(err.to_string()))?;
    let parsed: Value =
        serde_json::from_slice(&body).map_err(|err| GatewayError::Internal(err.to_string()))?;

@@ -0,0 +1,310 @@
+use crate::api::response::build_local_http_error_response;
+use crate::control::GatewayPublicRequestContext;
+use crate::headers::RequestBodyNormalizationError;
+use crate::{AppState, GatewayError};
+use axum::body::{to_bytes, Body, Bytes};
+use axum::http::{self, Response};
+use std::error::Error as StdError;
+use std::sync::Arc;
+use std::time::{Duration, Instant};
+use tokio::sync::Semaphore;
+use tracing::{info, warn};
+
+const REQUEST_BODY_READ_TIMEOUT_DETAIL: &str =
+    "Request body read timed out before the gateway could route the request";
+const REQUEST_BODY_READ_FAILED_DETAIL: &str = "Failed to read request body";
+
+#[derive(Debug, Clone)]
+pub(super) struct RequestBodyBufferPolicy {
+    max_bytes: u64,
+    read_timeout: Duration,
+    queue_timeout: Duration,
+    budget_bytes: usize,
+    budget: Arc<Semaphore>,
+}
+
+impl RequestBodyBufferPolicy {
+    pub(super) fn from_state(state: &AppState) -> Self {
+        Self {
+            max_bytes: crate::headers::max_request_body_bytes(),
+            read_timeout: state.frontdoor_runtime_guards.request_body_read_timeout,
+            queue_timeout: state.frontdoor_runtime_guards.internal_gate_queue_budget,
+            budget_bytes: state
+                .frontdoor_runtime_guards
+                .request_body_buffer_budget_bytes,
+            budget: Arc::clone(&state.request_body_buffer_budget),
+        }
+    }
+
+    #[cfg(test)]
+    pub(super) fn for_tests(max_bytes: u64, read_timeout: Duration) -> Self {
+        let budget_bytes = usize::try_from(max_bytes)
+            .unwrap_or(usize::MAX)
+            .max(crate::state::REQUEST_BODY_BUFFER_PERMIT_BYTES);
+        Self {
+            max_bytes,
+            read_timeout,
+            queue_timeout: read_timeout,
+            budget_bytes,
+            budget: Arc::new(Semaphore::new(
+                budget_bytes.saturating_add(crate::state::REQUEST_BODY_BUFFER_PERMIT_BYTES - 1)
+                    / crate::state::REQUEST_BODY_BUFFER_PERMIT_BYTES,
+            )),
+        }
+    }
+
+    #[cfg(test)]
+    pub(super) fn for_tests_with_budget(
+        max_bytes: u64,
+        read_timeout: Duration,
+        queue_timeout: Duration,
+        budget_bytes: usize,
+        budget: Arc<Semaphore>,
+    ) -> Self {
+        Self {
+            max_bytes,
+            read_timeout,
+            queue_timeout,
+            budget_bytes,
+            budget,
+        }
+    }
+}
+
+#[derive(Debug)]
+pub(super) enum RequestBodyBufferError {
+    Normalization(RequestBodyNormalizationError),
+    TooLarge {
+        limit_bytes: u64,
+    },
+    Overloaded {
+        requested_bytes: usize,
+        budget_bytes: usize,
+        timeout_ms: u64,
+    },
+    Timeout {
+        timeout_ms: u64,
+    },
+    ReadFailed {
+        message: String,
+    },
+}
+
+impl RequestBodyBufferError {
+    pub(super) fn http_status(&self) -> http::StatusCode {
+        match self {
+            Self::Normalization(error) => error.http_status(),
+            Self::TooLarge { .. } => http::StatusCode::PAYLOAD_TOO_LARGE,
+            Self::Overloaded { .. } => http::StatusCode::SERVICE_UNAVAILABLE,
+            Self::Timeout { .. } => http::StatusCode::REQUEST_TIMEOUT,
+            Self::ReadFailed { .. } => http::StatusCode::BAD_REQUEST,
+        }
+    }
+
+    fn client_message(&self) -> String {
+        match self {
+            Self::Normalization(error) => error.client_message(),
+            Self::TooLarge { limit_bytes } => format!("Request body exceeds {limit_bytes} bytes"),
+            Self::Overloaded { .. } => {
+                "Request body buffering capacity is temporarily exhausted".to_string()
+            }
+            Self::Timeout { .. } => REQUEST_BODY_READ_TIMEOUT_DETAIL.to_string(),
+            Self::ReadFailed { .. } => REQUEST_BODY_READ_FAILED_DETAIL.to_string(),
+        }
+    }
+
+    fn reason(&self) -> &'static str {
+        match self {
+            Self::Normalization(error) => match error {
+                RequestBodyNormalizationError::UnsupportedContentEncoding(_) => {
+                    "unsupported_content_encoding"
+                }
+                RequestBodyNormalizationError::DecodeFailed { .. } => "decode_failed",
+                RequestBodyNormalizationError::DecompressedBodyTooLarge { .. } => {
+                    "decompressed_body_too_large"
+                }
+                RequestBodyNormalizationError::RequestBodyTooLarge { .. } => {
+                    "request_body_too_large"
+                }
+            },
+            Self::TooLarge { .. } => "request_body_too_large",
+            Self::Overloaded { .. } => "request_body_buffer_overloaded",
+            Self::Timeout { .. } => "request_body_read_timeout",
+            Self::ReadFailed { .. } => "request_body_read_failed",
+        }
+    }
+}
+
+fn request_body_buffer_reservation_bytes(headers: &http::HeaderMap, max_bytes: u64) -> usize {
+    let max_bytes = usize::try_from(max_bytes).unwrap_or(usize::MAX);
+    let encoded = headers
+        .get(http::header::CONTENT_ENCODING)
+        .and_then(|value| value.to_str().ok())
+        .map(str::trim)
+        .is_some_and(|value| !value.is_empty() && !value.eq_ignore_ascii_case("identity"));
+    if encoded {
+        return max_bytes;
+    }
+    headers
+        .get(http::header::CONTENT_LENGTH)
+        .and_then(|value| value.to_str().ok())
+        .and_then(|value| value.trim().parse::<usize>().ok())
+        .map(|value| value.min(max_bytes))
+        .unwrap_or(max_bytes)
+}
+
+fn request_body_buffer_reservation_permits(reservation_bytes: usize) -> u32 {
+    let permits = reservation_bytes
+        .max(1)
+        .saturating_add(crate::state::REQUEST_BODY_BUFFER_PERMIT_BYTES - 1)
+        / crate::state::REQUEST_BODY_BUFFER_PERMIT_BYTES;
+    u32::try_from(permits).unwrap_or(u32::MAX).max(1)
+}
+
+pub(super) async fn buffer_and_normalize_request_body(
+    request_body: &mut Option<Body>,
+    headers: &mut http::HeaderMap,
+    body_owner_expectation: &'static str,
+    trace_id: &str,
+    method: &http::Method,
+    path_and_query: &str,
+    phase: &'static str,
+    policy: RequestBodyBufferPolicy,
+) -> Result<Bytes, RequestBodyBufferError> {
+    if let Err(err) =
+        crate::headers::check_request_content_length_with_limit(headers, policy.max_bytes)
+    {
+        return Err(RequestBodyBufferError::Normalization(err));
+    }
+
+    let reservation_bytes = request_body_buffer_reservation_bytes(headers, policy.max_bytes);
+    let reservation_permits = request_body_buffer_reservation_permits(reservation_bytes);
+    let queue_timeout_ms = policy.queue_timeout.as_millis() as u64;
+    let _budget_permit = match tokio::time::timeout(
+        policy.queue_timeout,
+        Arc::clone(&policy.budget).acquire_many_owned(reservation_permits),
+    )
+    .await
+    {
+        Ok(Ok(permit)) => permit,
+        Ok(Err(_)) | Err(_) => {
+            return Err(RequestBodyBufferError::Overloaded {
+                requested_bytes: reservation_bytes,
+                budget_bytes: policy.budget_bytes,
+                timeout_ms: queue_timeout_ms,
+            });
+        }
+    };
+
+    let read_started_at = Instant::now();
+    let timeout_ms = policy.read_timeout.as_millis() as u64;
+    info!(
+        event_name = "frontdoor_request_body_buffer_started",
+        log_type = "event",
+        trace_id,
+        method = %method,
+        path = %path_and_query,
+        phase,
+        max_body_bytes = policy.max_bytes,
+        reserved_body_bytes = reservation_bytes,
+        body_buffer_budget_bytes = policy.budget_bytes,
+        timeout_ms,
+        "gateway started buffering request body"
+    );
+
+    let body_limit = usize::try_from(policy.max_bytes).unwrap_or(usize::MAX);
+    let body = match tokio::time::timeout(
+        policy.read_timeout,
+        to_bytes(
+            request_body.take().expect(body_owner_expectation),
+            body_limit,
+        ),
+    )
+    .await
+    {
+        Ok(Ok(body)) => body,
+        Ok(Err(err)) if request_body_collection_exceeded_limit(&err) => {
+            return Err(RequestBodyBufferError::TooLarge {
+                limit_bytes: policy.max_bytes,
+            });
+        }
+        Ok(Err(err)) => {
+            return Err(RequestBodyBufferError::ReadFailed {
+                message: err.to_string(),
+            });
+        }
+        Err(_) => {
+            return Err(RequestBodyBufferError::Timeout { timeout_ms });
+        }
+    };
+
+    let normalized = crate::headers::normalize_request_body_headers_and_bytes_with_limit(
+        headers,
+        body,
+        policy.max_bytes,
+    )
+    .map_err(RequestBodyBufferError::Normalization)?;
+    info!(
+        event_name = "frontdoor_request_body_buffer_completed",
+        log_type = "event",
+        trace_id,
+        method = %method,
+        path = %path_and_query,
+        phase,
+        body_bytes = normalized.len(),
+        elapsed_ms = read_started_at.elapsed().as_millis() as u64,
+        "gateway completed buffering request body"
+    );
+    Ok(normalized)
+}
+
+fn request_body_collection_exceeded_limit(error: &(dyn StdError + 'static)) -> bool {
+    let mut current = Some(error);
+    while let Some(error) = current {
+        if error.to_string().contains("length limit exceeded") {
+            return true;
+        }
+        current = error.source();
+    }
+    false
+}
+
+pub(super) fn build_request_body_buffer_error_response(
+    trace_id: &str,
+    request_context: &GatewayPublicRequestContext,
+    error: &RequestBodyBufferError,
+) -> Result<Response<Body>, GatewayError> {
+    warn!(
+        event_name = "frontdoor_request_body_buffer_failed",
+        log_type = "ops",
+        trace_id,
+        method = %request_context.request_method,
+        path = %request_context.request_path_and_query(),
+        status_code = error.http_status().as_u16(),
+        reason = error.reason(),
+        detail = %error.client_message(),
+        read_error = match error {
+            RequestBodyBufferError::ReadFailed { message } => message.as_str(),
+            _ => "",
+        },
+        buffer_requested_bytes = match error {
+            RequestBodyBufferError::Overloaded { requested_bytes, .. } => *requested_bytes,
+            _ => 0,
+        },
+        buffer_budget_bytes = match error {
+            RequestBodyBufferError::Overloaded { budget_bytes, .. } => *budget_bytes,
+            _ => 0,
+        },
+        buffer_queue_timeout_ms = match error {
+            RequestBodyBufferError::Overloaded { timeout_ms, .. } => *timeout_ms,
+            _ => 0,
+        },
+        "gateway rejected request body before local execution planning"
+    );
+    build_local_http_error_response(
+        trace_id,
+        request_context.control_decision.as_ref(),
+        error.http_status(),
+        error.client_message().as_str(),
+    )
+}
@@ -1,5 +1,10 @@
+mod body_buffer;
 mod local;

+use self::body_buffer::{
+    buffer_and_normalize_request_body, build_request_body_buffer_error_response,
+    RequestBodyBufferError, RequestBodyBufferPolicy,
+};
 use self::local::{
    maybe_build_local_admin_proxy_response, maybe_build_local_internal_proxy_response,
 };
@@ -52,7 +57,7 @@ use crate::handlers::shared::{
 };
 use crate::headers::{
    effective_client_ip, extract_or_generate_trace_id, request_origin_from_headers_and_remote_addr,
-    should_skip_request_header, RequestBodyNormalizationError,
+    should_skip_request_header,
 };
 use crate::router::RequestAdmissionError;
 use crate::scheduler::candidate::{
@@ -70,11 +75,7 @@ use axum::extract::{ConnectInfo, Request, State};
 use axum::http::{self, header::HeaderName, header::HeaderValue, Response};
 use futures_util::StreamExt;
 use sha2::{Digest, Sha256};
-use std::{
-    collections::BTreeMap,
-    error::Error as StdError,
-    time::{Duration, Instant},
-};
+use std::{collections::BTreeMap, time::Instant};
 use tracing::{debug, info, warn};

 const OPENAI_CHAT_LOCAL_EXECUTION_RUNTIME_MISS_DETAIL: &str =
@@ -98,201 +99,11 @@ const LOCAL_EXECUTION_LOOP_DETECTED_DETAIL: &str =
    "Gateway detected an execution runtime request loop back into the local frontdoor";
 const AUTH_API_KEY_CONCURRENCY_LIMIT_REACHED_DETAIL: &str =
    "当前调用方 API Key 并发请求数已达上限，请稍后重试";
-const REQUEST_BODY_READ_TIMEOUT_DETAIL: &str =
-    "Request body read timed out before the gateway could route the request";
-const REQUEST_BODY_READ_FAILED_DETAIL: &str = "Failed to read request body";
 const LOCAL_EXECUTION_PLANNING_TIMEOUT_DETAIL: &str =
    "当前 AI 请求在本地执行规划阶段超时，请稍后重试";
 const EXECUTION_PATH_TUNNEL_AFFINITY_FORWARD: &str = "tunnel_affinity_forward";
 const MANAGEMENT_TOKEN_PREFIX: &str = "ae-";
 const LEGACY_MANAGEMENT_TOKEN_PREFIX: &str = "ae_";
-
-#[derive(Debug, Clone, Copy)]
-struct RequestBodyBufferPolicy {
-    max_bytes: u64,
-    read_timeout: Duration,
-}
-
-impl RequestBodyBufferPolicy {
-    fn from_state(state: &AppState) -> Self {
-        Self {
-            max_bytes: crate::headers::max_request_body_bytes(),
-            read_timeout: state.frontdoor_runtime_guards.request_body_read_timeout,
-        }
-    }
-
-    #[cfg(test)]
-    fn for_tests(max_bytes: u64, read_timeout: Duration) -> Self {
-        Self {
-            max_bytes,
-            read_timeout,
-        }
-    }
-}
-
-#[derive(Debug)]
-enum RequestBodyBufferError {
-    Normalization(RequestBodyNormalizationError),
-    TooLarge { limit_bytes: u64 },
-    Timeout { timeout_ms: u64 },
-    ReadFailed { message: String },
-}
-
-impl RequestBodyBufferError {
-    fn http_status(&self) -> http::StatusCode {
-        match self {
-            Self::Normalization(error) => error.http_status(),
-            Self::TooLarge { .. } => http::StatusCode::PAYLOAD_TOO_LARGE,
-            Self::Timeout { .. } => http::StatusCode::REQUEST_TIMEOUT,
-            Self::ReadFailed { .. } => http::StatusCode::BAD_REQUEST,
-        }
-    }
-
-    fn client_message(&self) -> String {
-        match self {
-            Self::Normalization(error) => error.client_message(),
-            Self::TooLarge { limit_bytes } => format!("Request body exceeds {limit_bytes} bytes"),
-            Self::Timeout { .. } => REQUEST_BODY_READ_TIMEOUT_DETAIL.to_string(),
-            Self::ReadFailed { .. } => REQUEST_BODY_READ_FAILED_DETAIL.to_string(),
-        }
-    }
-
-    fn reason(&self) -> &'static str {
-        match self {
-            Self::Normalization(error) => match error {
-                RequestBodyNormalizationError::UnsupportedContentEncoding(_) => {
-                    "unsupported_content_encoding"
-                }
-                RequestBodyNormalizationError::DecodeFailed { .. } => "decode_failed",
-                RequestBodyNormalizationError::DecompressedBodyTooLarge { .. } => {
-                    "decompressed_body_too_large"
-                }
-                RequestBodyNormalizationError::RequestBodyTooLarge { .. } => {
-                    "request_body_too_large"
-                }
-            },
-            Self::TooLarge { .. } => "request_body_too_large",
-            Self::Timeout { .. } => "request_body_read_timeout",
-            Self::ReadFailed { .. } => "request_body_read_failed",
-        }
-    }
-}
-
-async fn buffer_and_normalize_request_body(
-    request_body: &mut Option<Body>,
-    headers: &mut http::HeaderMap,
-    body_owner_expectation: &'static str,
-    trace_id: &str,
-    method: &http::Method,
-    path_and_query: &str,
-    phase: &'static str,
-    policy: RequestBodyBufferPolicy,
-) -> Result<Bytes, RequestBodyBufferError> {
-    if let Err(err) =
-        crate::headers::check_request_content_length_with_limit(headers, policy.max_bytes)
-    {
-        return Err(RequestBodyBufferError::Normalization(err));
-    }
-
-    let read_started_at = Instant::now();
-    let timeout_ms = policy.read_timeout.as_millis() as u64;
-    info!(
-        event_name = "frontdoor_request_body_buffer_started",
-        log_type = "event",
-        trace_id,
-        method = %method,
-        path = %path_and_query,
-        phase,
-        max_body_bytes = policy.max_bytes,
-        timeout_ms,
-        "gateway started buffering request body"
-    );
-
-    let body_limit = usize::try_from(policy.max_bytes).unwrap_or(usize::MAX);
-    let body = match tokio::time::timeout(
-        policy.read_timeout,
-        to_bytes(
-            request_body.take().expect(body_owner_expectation),
-            body_limit,
-        ),
-    )
-    .await
-    {
-        Ok(Ok(body)) => body,
-        Ok(Err(err)) if request_body_collection_exceeded_limit(&err) => {
-            return Err(RequestBodyBufferError::TooLarge {
-                limit_bytes: policy.max_bytes,
-            });
-        }
-        Ok(Err(err)) => {
-            return Err(RequestBodyBufferError::ReadFailed {
-                message: err.to_string(),
-            });
-        }
-        Err(_) => {
-            return Err(RequestBodyBufferError::Timeout { timeout_ms });
-        }
-    };
-
-    let normalized = crate::headers::normalize_request_body_headers_and_bytes_with_limit(
-        headers,
-        body,
-        policy.max_bytes,
-    )
-    .map_err(RequestBodyBufferError::Normalization)?;
-    info!(
-        event_name = "frontdoor_request_body_buffer_completed",
-        log_type = "event",
-        trace_id,
-        method = %method,
-        path = %path_and_query,
-        phase,
-        body_bytes = normalized.len(),
-        elapsed_ms = read_started_at.elapsed().as_millis() as u64,
-        "gateway completed request body buffering"
-    );
-    Ok(normalized)
-}
-
-fn request_body_collection_exceeded_limit(error: &(dyn StdError + 'static)) -> bool {
-    let mut current = Some(error);
-    while let Some(error) = current {
-        if error.to_string().contains("length limit exceeded") {
-            return true;
-        }
-        current = error.source();
-    }
-    false
-}
-
-fn build_request_body_buffer_error_response(
-    trace_id: &str,
-    request_context: &GatewayPublicRequestContext,
-    error: &RequestBodyBufferError,
-) -> Result<Response<Body>, GatewayError> {
-    warn!(
-        event_name = "frontdoor_request_body_buffer_failed",
-        log_type = "ops",
-        trace_id,
-        method = %request_context.request_method,
-        path = %request_context.request_path_and_query(),
-        status_code = error.http_status().as_u16(),
-        reason = error.reason(),
-        detail = %error.client_message(),
-        read_error = match error {
-            RequestBodyBufferError::ReadFailed { message } => message.as_str(),
-            _ => "",
-        },
-        "gateway rejected request body before local execution planning"
-    );
-    build_local_http_error_response(
-        trace_id,
-        request_context.control_decision.as_ref(),
-        error.http_status(),
-        error.client_message().as_str(),
-    )
-}
-
 fn finalize_request_body_buffer_rejection(
    state: &AppState,
    request_context: &GatewayPublicRequestContext,
@@ -303,12 +114,17 @@ fn finalize_request_body_buffer_rejection(
    error: &RequestBodyBufferError,
 ) -> Result<Response<Body>, GatewayError> {
    let response = build_request_body_buffer_error_response(trace_id, request_context, error)?;
+    let execution_path = if matches!(error, RequestBodyBufferError::Overloaded { .. }) {
+        EXECUTION_PATH_LOCAL_OVERLOADED
+    } else {
+        EXECUTION_PATH_LOCAL_INVALID_REQUEST
+    };
    Ok(finalize_gateway_response_with_context(
        state,
        response,
        remote_addr,
        request_context,
-        EXECUTION_PATH_LOCAL_INVALID_REQUEST,
+        execution_path,
        started_at,
        request_permit,
    ))
@@ -776,9 +592,17 @@ async fn restore_redacted_sync_execution_response(
        return Ok(Response::from_parts(parts, body));
    };
    let mut headers = collect_response_headers(&parts.headers);
-    let body_bytes = to_bytes(body, usize::MAX)
-        .await
-        .map_err(|err| GatewayError::Internal(err.to_string()))?;
+    let response_body_limit = crate::headers::max_redacted_sync_response_body_bytes();
+    let body_bytes = to_bytes(
+        body,
+        usize::try_from(response_body_limit).unwrap_or(usize::MAX),
+    )
+    .await
+    .map_err(|err| {
+        GatewayError::Internal(format!(
+            "failed to buffer redacted sync response within {response_body_limit} bytes: {err}"
+        ))
+    })?;
    let restored =
        crate::privacy::restore_sync_response_body(&mut headers, body_bytes.as_ref(), &session)?;
    replace_response_headers(&mut parts.headers, &headers)?;
@@ -1041,49 +865,6 @@ async fn proxy_request_inner(
    let started_at = Instant::now();
    let client_ip = effective_client_ip(request.headers(), &remote_addr);
    let trace_id = extract_or_generate_trace_id(request.headers());
-    match state.admin_security_ip_blacklisted(client_ip).await {
-        Ok(true) => {
-            warn!(
-                event_name = "frontdoor_ip_blacklist_rejected",
-                log_type = "event",
-                trace_id = %trace_id,
-                client_ip = %client_ip,
-                path = %request.uri().path(),
-                "gateway rejected blacklisted client IP"
-            );
-            let response = build_local_http_error_response(
-                &trace_id,
-                None,
-                http::StatusCode::FORBIDDEN,
-                "当前 IP 已被禁止访问",
-            )?;
-            return Ok(finalize_gateway_response(
-                &state,
-                response,
-                &trace_id,
-                &remote_addr,
-                request.method(),
-                request
-                    .uri()
-                    .path_and_query()
-                    .map(|value| value.as_str())
-                    .unwrap_or("/"),
-                None,
-                EXECUTION_PATH_LOCAL_AUTH_DENIED,
-                &started_at,
-                None,
-            ));
-        }
-        Ok(false) => {}
-        Err(err) => warn!(
-            event_name = "frontdoor_ip_blacklist_check_failed",
-            log_type = "ops",
-            trace_id = %trace_id,
-            client_ip = %client_ip,
-            error = ?err,
-            "gateway failed open after IP blacklist check error"
-        ),
-    }
    let accepted_at = request
        .extensions()
        .get::<crate::middleware::GatewayRequestAcceptedAt>()
@@ -1161,6 +942,49 @@ async fn proxy_request_inner(
    };
    let request_admission_ms = started_at.elapsed().as_millis() as u64;
    observe_gateway_stage_ms("frontdoor_admission", request_admission_ms);
+    match state.admin_security_ip_blacklisted(client_ip).await {
+        Ok(true) => {
+            warn!(
+                event_name = "frontdoor_ip_blacklist_rejected",
+                log_type = "event",
+                trace_id = %trace_id,
+                client_ip = %client_ip,
+                path = %request.uri().path(),
+                "gateway rejected blacklisted client IP"
+            );
+            let response = build_local_http_error_response(
+                &trace_id,
+                None,
+                http::StatusCode::FORBIDDEN,
+                "当前 IP 已被禁止访问",
+            )?;
+            return Ok(finalize_gateway_response(
+                &state,
+                response,
+                &trace_id,
+                &remote_addr,
+                request.method(),
+                request
+                    .uri()
+                    .path_and_query()
+                    .map(|value| value.as_str())
+                    .unwrap_or("/"),
+                None,
+                EXECUTION_PATH_LOCAL_AUTH_DENIED,
+                &started_at,
+                request_permit.take(),
+            ));
+        }
+        Ok(false) => {}
+        Err(err) => warn!(
+            event_name = "frontdoor_ip_blacklist_check_failed",
+            log_type = "ops",
+            trace_id = %trace_id,
+            client_ip = %client_ip,
+            error = ?err,
+            "gateway failed open after IP blacklist check error"
+        ),
+    }
    let (mut parts, body) = request.into_parts();
    let redaction_slot = crate::privacy::RedactionSessionSlot::default();
    parts.extensions.insert(redaction_slot.clone());
@@ -2432,6 +2256,7 @@ fn local_execution_runtime_miss_route_detail(

 #[cfg(test)]
 mod tests {
+    use std::sync::Arc;
    use std::time::Duration;

    use super::{
@@ -2442,8 +2267,9 @@ mod tests {
        RequestBodyBufferPolicy,
    };
    use axum::body::{to_bytes, Body, Bytes};
-    use axum::http::{header, HeaderMap, Method, Response};
+    use axum::http::{header, HeaderMap, HeaderValue, Method, Response};
    use serde_json::json;
+    use tokio::sync::Semaphore;

    #[test]
    fn api_key_remote_ip_allows_unrestricted_keys() {
@@ -2622,6 +2448,45 @@ mod tests {
        ));
    }

+    #[tokio::test]
+    async fn request_body_buffer_rejects_when_weighted_budget_is_exhausted() {
+        let budget = Arc::new(Semaphore::new(1));
+        let _held = Arc::clone(&budget)
+            .acquire_owned()
+            .await
+            .expect("test budget should be open");
+        let mut body = Some(Body::from(Bytes::from_static(b"{}")));
+        let mut headers = HeaderMap::new();
+        headers.insert(header::CONTENT_LENGTH, HeaderValue::from_static("2"));
+
+        let err = buffer_and_normalize_request_body(
+            &mut body,
+            &mut headers,
+            "test owns body",
+            "trace-body-budget",
+            &Method::POST,
+            "/v1/responses",
+            "test",
+            RequestBodyBufferPolicy::for_tests_with_budget(
+                1024,
+                Duration::from_secs(1),
+                Duration::from_millis(5),
+                crate::state::REQUEST_BODY_BUFFER_PERMIT_BYTES,
+                budget,
+            ),
+        )
+        .await
+        .expect_err("exhausted body budget should reject quickly");
+
+        assert!(matches!(
+            err,
+            RequestBodyBufferError::Overloaded {
+                requested_bytes: 2,
+                ..
+            }
+        ));
+    }
+
    #[test]
    fn runtime_miss_detail_returns_model_specific_stream_message_when_candidates_are_unavailable() {
        let decision = GatewayControlDecision::synthetic(
@@ -464,7 +464,7 @@ async fn complete_oauth_login(
        .cloned()
        .collect::<Vec<_>>();
    let body = login_response.into_body();
-    let body = match to_bytes(body, usize::MAX).await {
+    let body = match to_bytes(body, crate::headers::max_internal_buffered_body_bytes()).await {
        Ok(value) => value,
        Err(_) => return redirect_oauth_error(Some(frontend_callback_url), "provider_unavailable"),
    };