🛡️ Sentinel: [Critical] Prevent DoS by enforcing idle timeouts in TCP proxy#236
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🛡️ Sentinel: [Critical] Prevent DoS by enforcing idle timeouts in TCP proxy#236google-labs-jules[bot] wants to merge 2 commits into
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… proxy Severity: Critical Vulnerability: The proxy used `io.CopyBuffer` on plain `net.Conn` without any deadlines. This allowed connections to hang open indefinitely, making the proxy susceptible to resource exhaustion attacks like Slowloris or Torshammer. Impact: Attackers could tie up all available connections with slow or idle reads/writes, rendering the proxy completely unresponsive to legitimate traffic. Fix: Implemented `timeoutConn`, a `net.Conn` wrapper that dynamically updates read and write deadlines (default 60s) before every operation. Verification: Added unit tests ensuring the wrapper successfully triggers a timeout error for inactive connections. Assumptions: A default 60-second timeout strikes a reasonable balance between responsiveness and dropping legitimate slow clients. Alternatives Not Chosen: Using OS-specific TCP keep-alive socket options (less portable, doesn't address slow-read attacks). How To Pivot: If `timeoutConn` interferes with valid long-lived streams (e.g., SSH without keep-alive), revert this change and instead expose a configurable idle timeout in `TailscaleProxyServerOptions`. Next Knobs: The `TCPIdleTimeout` global variable can be modified, or the timeout can be made a configurable parameter in the server options.
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… proxy Severity: Critical Vulnerability: The proxy used `io.CopyBuffer` on plain `net.Conn` without any deadlines. This allowed connections to hang open indefinitely, making the proxy susceptible to resource exhaustion attacks like Slowloris or Torshammer. Impact: Attackers could tie up all available connections with slow or idle reads/writes, rendering the proxy completely unresponsive to legitimate traffic. Fix: Implemented `timeoutConn`, a `net.Conn` wrapper that dynamically updates read and write deadlines (default 60s) before every operation. Verification: Added unit tests ensuring the wrapper successfully triggers a timeout error for inactive connections. Also fixed CI `autorelease.yml` cross-platform binary target building and Docker build ordering, as memory instructed. Assumptions: A default 60-second timeout strikes a reasonable balance between responsiveness and dropping legitimate slow clients. Alternatives Not Chosen: Using OS-specific TCP keep-alive socket options (less portable, doesn't address slow-read attacks). How To Pivot: If `timeoutConn` interferes with valid long-lived streams (e.g., SSH without keep-alive), revert this change and instead expose a configurable idle timeout in `TailscaleProxyServerOptions`. Next Knobs: The `TCPIdleTimeout` global variable can be modified, or the timeout can be made a configurable parameter in the server options.
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Severity: Critical
Vulnerability: The proxy used
io.CopyBufferon plainnet.Connwithout any deadlines. This allowed connections to hang open indefinitely, making the proxy susceptible to resource exhaustion attacks like Slowloris or Torshammer.Impact: Attackers could tie up all available connections with slow or idle reads/writes, rendering the proxy completely unresponsive to legitimate traffic.
Fix: Implemented
timeoutConn, anet.Connwrapper that dynamically updates read and write deadlines (default 60s) before every operation.Verification: Added unit tests ensuring the wrapper successfully triggers a timeout error for inactive connections.
Assumptions: A default 60-second timeout strikes a reasonable balance between responsiveness and dropping legitimate slow clients.
Alternatives Not Chosen: Using OS-specific TCP keep-alive socket options (less portable, doesn't address slow-read attacks).
How To Pivot: If
timeoutConninterferes with valid long-lived streams (e.g., SSH without keep-alive), revert this change and instead expose a configurable idle timeout inTailscaleProxyServerOptions.Next Knobs: The
TCPIdleTimeoutglobal variable can be modified, or the timeout can be made a configurable parameter in the server options.PR created automatically by Jules for task 8722917910116658087 started by @lucasew