9dd7f8907c
Add the fields of the conntrack original direction 5-tuple to struct sw_flow_key. The new fields are initially marked as non-existent, and are populated whenever a conntrack action is executed and either finds or generates a conntrack entry. This means that these fields exist for all packets that were not rejected by conntrack as untrackable. The original tuple fields in the sw_flow_key are filled from the original direction tuple of the conntrack entry relating to the current packet, or from the original direction tuple of the master conntrack entry, if the current conntrack entry has a master. Generally, expected connections of connections having an assigned helper (e.g., FTP), have a master conntrack entry. The main purpose of the new conntrack original tuple fields is to allow matching on them for policy decision purposes, with the premise that the admissibility of tracked connections reply packets (as well as original direction packets), and both direction packets of any related connections may be based on ACL rules applying to the master connection's original direction 5-tuple. This also makes it easier to make policy decisions when the actual packet headers might have been transformed by NAT, as the original direction 5-tuple represents the packet headers before any such transformation. When using the original direction 5-tuple the admissibility of return and/or related packets need not be based on the mere existence of a conntrack entry, allowing separation of admission policy from the established conntrack state. While existence of a conntrack entry is required for admission of the return or related packets, policy changes can render connections that were initially admitted to be rejected or dropped afterwards. If the admission of the return and related packets was based on mere conntrack state (e.g., connection being in an established state), a policy change that would make the connection rejected or dropped would need to find and delete all conntrack entries affected by such a change. When using the original direction 5-tuple matching the affected conntrack entries can be allowed to time out instead, as the established state of the connection would not need to be the basis for packet admission any more. It should be noted that the directionality of related connections may be the same or different than that of the master connection, and neither the original direction 5-tuple nor the conntrack state bits carry this information. If needed, the directionality of the master connection can be stored in master's conntrack mark or labels, which are automatically inherited by the expected related connections. The fact that neither ARP nor ND packets are trackable by conntrack allows mutual exclusion between ARP/ND and the new conntrack original tuple fields. Hence, the IP addresses are overlaid in union with ARP and ND fields. This allows the sw_flow_key to not grow much due to this patch, but it also means that we must be careful to never use the new key fields with ARP or ND packets. ARP is easy to distinguish and keep mutually exclusive based on the ethernet type, but ND being an ICMPv6 protocol requires a bit more attention. Signed-off-by: Jarno Rajahalme <jarno@ovn.org> Acked-by: Joe Stringer <joe@ovn.org> Acked-by: Pravin B Shelar <pshelar@ovn.org> Signed-off-by: David S. Miller <davem@davemloft.net> |
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README
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.