1. 18 Jul, 2020 2 commits
    • Jakub Sitnicki's avatar
      bpf: Introduce SK_LOOKUP program type with a dedicated attach point · e9ddbb77
      Jakub Sitnicki authored
      Add a new program type BPF_PROG_TYPE_SK_LOOKUP with a dedicated attach type
      BPF_SK_LOOKUP. The new program kind is to be invoked by the transport layer
      when looking up a listening socket for a new connection request for
      connection oriented protocols, or when looking up an unconnected socket for
      a packet for connection-less protocols.
      
      When called, SK_LOOKUP BPF program can select a socket that will receive
      the packet. This serves as a mechanism to overcome the limits of what
      bind() API allows to express. Two use-cases driving this work are:
      
       (1) steer packets destined to an IP range, on fixed port to a socket
      
           192.0.2.0/24, port 80 -> NGINX socket
      
       (2) steer packets destined to an IP address, on any port to a socket
      
           198.51.100.1, any port -> L7 proxy socket
      
      In its run-time context program receives information about the packet that
      triggered the socket lookup. Namely IP version, L4 protocol identifier, and
      address 4-tuple. Context can be further extended to include ingress
      interface identifier.
      
      To select a socket BPF program fetches it from a map holding socket
      references, like SOCKMAP or SOCKHASH, and calls bpf_sk_assign(ctx, sk, ...)
      helper to record the selection. Transport layer then uses the selected
      socket as a result of socket lookup.
      
      In its basic form, SK_LOOKUP acts as a filter and hence must return either
      SK_PASS or SK_DROP. If the program returns with SK_PASS, transport should
      look for a socket to receive the packet, or use the one selected by the
      program if available, while SK_DROP informs the transport layer that the
      lookup should fail.
      
      This patch only enables the user to attach an SK_LOOKUP program to a
      network namespace. Subsequent patches hook it up to run on local delivery
      path in ipv4 and ipv6 stacks.
      Suggested-by: default avatarMarek Majkowski <marek@cloudflare.com>
      Signed-off-by: default avatarJakub Sitnicki <jakub@cloudflare.com>
      Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      Link: https://lore.kernel.org/bpf/20200717103536.397595-3-jakub@cloudflare.com
      e9ddbb77
    • Jakub Sitnicki's avatar
      bpf, netns: Handle multiple link attachments · ce3aa9cc
      Jakub Sitnicki authored
      Extend the BPF netns link callbacks to rebuild (grow/shrink) or update the
      prog_array at given position when link gets attached/updated/released.
      
      This let's us lift the limit of having just one link attached for the new
      attach type introduced by subsequent patch.
      
      No functional changes intended.
      Signed-off-by: default avatarJakub Sitnicki <jakub@cloudflare.com>
      Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
      Link: https://lore.kernel.org/bpf/20200717103536.397595-2-jakub@cloudflare.com
      ce3aa9cc
  2. 16 Jul, 2020 38 commits