This patchset adds support for per-UID routing. It allows the administrator to configure rules such as:
ip rule add uidrange 100-200 lookup 123 This functionality has been in use by all Android devices since 5.0, which was released in late 2014. It is primarily used to impose per-app routing policies (on Android, every app has its own UID) without having to resort to rerouting packets in iptables, which breaks getsockname() and MTU/MSS calculation, and generally disrupts end-to-end connectivity. This patch series is similar to the code currently used on Android, but has better correctness and performance because it stores the UID in the socket instead of calling sock_i_uid. This avoids contention on sk->sk_callback_lock, and makes it possible to correctly route a socket on which userspace has called close(), for which sock_i_uid will return 0.