Merge branch 'macsec'
Sabrina Dubroca says: ==================== MACsec IEEE 802.1AE implementation MACsec (IEEE 802.1AE [0]) is a protocol that provides security for wired ethernet LANs. MACsec offers two protection modes: authentication only, or authenticated encryption. MACsec defines "secure channels" that allow transmission from one node to one or more others. Communication on a channel is done over a succession of "secure associations", that each use a specific key. Secure associations are identified by their "association number" in the range 0..3. A secure association is retired when its 32-bit packet number would wrap, and the same association number can later be reused with a new key and packet number. The standard mode of encryption is GCM AES with 128 bits keys, although an extension allows 256 bits keys [1] (not implemented in this submission). When using MACsec, an extra header, called "SecTAG", is added between the ethernet header and the original payload: +---------------------------------+----------------+----------------+ | (MACsec ethertype) | TCI_AN | SL | +---------------------------------+----------------+----------------+ | Packet Number | +-------------------------------------------------------------------+ | Secure Channel Identifier | | (optional) | +-------------------------------------------------------------------+ TCI_AN: version end_station sci_present scb encrypted changed_text association_number (2 bits) SL: short_length (6 bits) unused (2 bits) The ethertype for the packet is set to 0x88E5, and the original ethertype becomes part of the secure payload, which may be encrypted. The ethernet header and the SecTAG are always transmitted in the clear, but are integrity-protected. MACsec supports optional replay protection with a configurable replay window. MACsec is designed to be used with the MKA extension to 802.1X (MACsec Key Agreement protocol) [2], which provides channel attribution and key distribution to the nodes, but can also be used with static keys getting fed manually by an administrator. Optional (not supported yet) features: - confidentiality offset: in encryption mode, part of the payload may be left unencrypted. - choice of cipher suite: GCM AES with 256 bits has been standardised [1]. Implementation A netdevice is created on top of a real device for each TX secure channel, like we do for VLANs. Multiple TX channels can be created on top of the same underlying device. Several other approaches were considered for the RX path: - dev_add_pack: doesn't work, because we want to filter out unprotected packets - transparent mode: MACsec would be enabled directly on the real netdevice. For this, we cannot use a rx_handler directly because MACsec must be available for underlying devices enslaved in a bridge or in a bond, so we need a hook directly in __netif_receive_skb_core. This approach makes it harder to filter non-encrypted packets on RX without forcing the user to setup some rules, so the "transparent" mode is not so transparent after all. It also makes TX more complex than with a dedicated netdevice. One issue with the proposed implementation is that the qdisc layer for the real device operates on already encrypted packets. Netlink API This is currently a mix of rtnetlink (to create the device and set up the TX channel) and genl (for RX channels, secure associations and their keys). genl provides clean demultiplexing of the {TX,RX}{SC,SA} commands. Use cases The normal use case is wired LANs, including veth and slave devices for bonding/teaming or bridges. MACsec can also be used on any device that makes a full ethernet header visible, for example VXLAN. The VXLAN+MACsec setup would be: hypervisor | virtual machine <real_dev>---<VXLAN>---|---<dev>---<macsec_dev> And the packets would look like this: | eth | IP | UDP | VXLAN | eth | MACsec | IP | ... | MACsec ICV | One benefit on this approach to encryption in the cloud is that the payload is encrypted by the tenant, not by the tunnel provider, thus the tenant has full control over the keys. Changes from v1: - rework netlink API after discussion with Johannes Berg - nest attributes, rename - export stats as separate attributes - add some comments - misc small fixes (rcu, constants, struct organization) Changes from RFCv2: - fix ENCODING_SA param validation - add parent link to netlink ifdumps Changes from RFCv1: - addressed comments from Florian and Paolo + kbuild robot - also perform post-decrypt handling after crypto callback - fixed ->dellink behavior Future plans: - offload to hardware, on nics that support it - implement optional features [0] http://standards.ieee.org/getieee802/download/802.1AE-2006.pdf [1] http://standards.ieee.org/getieee802/download/802.1AEbn-2011.pdf [2] http://standards.ieee.org/getieee802/download/802.1X-2010.pdf [3] RFCv1: http://www.spinics.net/lists/netdev/msg358151.html [4] RFCv2: http://www.spinics.net/lists/netdev/msg362389.html [5] v1: http://www.spinics.net/lists/netdev/msg367959.html ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
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drivers/net/macsec.c
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