Necko: Sandboxing TCP/UDP socket in a separate process

Objectives

Move all the network and socket operations to an isolated process.

Goals

• For security
  • Sandboxing network access into a separate process, preventing chrome process from opening socket
  • Preventing protocol security hole to be used to control the entire browser
• For stability
  • Allow recovering network layer without rebooting firefox, if crash/assertion is detected in the socket process
• For performance
  • No major regression found for start-up performance and network throughput

Requirements

HTTP Channel

• load protocol configuration from Gecko preference
• Alternative Service, uses AlternateServices.txt
• Cookie access need to stay on chrome process
• WebRequest can intercept http request/response
• Download triggered by unknown content type needs to divert back to chrome process

TCP Socket

• permission controlled by chrome process
• prevent system port to be bind

UDP Socket

• permission controlled by chrome process
• prevent system port to be bind

DNS

• permission to do system call for DNS query
• thread pool for doing blocking operation in parallel
• allow both chrome process and content process to request DNS query directly to socket process

Cache

• choice #1: stay in chrome process:
  • need a copy of full http response from socket process
  • for RCWN, need to delay the construction for ODA IPC endpoint until we know cache win or network win
• choice #2: move to socket process:
  • need access cache data file from socket process
  • need to move cache evaluation code from nsHttpChannel to other class on socket process

Proxy

• load proxy configuration from Gecko preference
• PAC loading and execution, require JS runtime
• access system proxy setting
• create and connect to name pipe

PSM

• touches the preferences and various txt files in the profile
• Cert store, uses cert*.db and key*.db
• revocation information (i.e. nsICertBlocklist), uses revocations.txt
• certificate error overrides (nsICertOverrideService), uses cert_override.txt.
• HSTS/HPKP information (nsISiteSecurityService, although we've already implemented a way to access this information in non-parent processes), uses SiteSecurityServiceState.txt, SecurityPreloadState.txt
• external PKCS#11 module, require DLL loading from arbitrary file path

NSS

• uses the cert/key/secmod.db files as well as pkcs11.txt.
• access system file, e.g. /dev/urandom and system policy files under /etc

PKI/PKIX

doesn't interact with preferences or file directly.

Sandboxing

• Chrome process is still the only secure zone. Every IPC interface received at Chrome process should be audited
• IPC to content process or socket process should at least do sanity check in the receiver side
• Better not providing interface to create arbitrary TCP/UDP connection

DevTool

• require TCP/UDP socket
• require JS runtime for devtool protocol

TODOs

• hook ProcessHangMonitor
• hook CrashReporter
• hook MemoryPresure
• hook MemoryReporter
• ensure Telemetry works
• ensure MOZ_LOG works
• remove XPCOM and support only C++ implementation