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Jonathan T. Leighton says: ==================== IPv4-mapped on wire, :: dst address issue Under some circumstances IPv6 datagrams are sent with IPv4-mapped IPv6 addresses as the source. Given an IPv6 socket bound to an IPv4-mapped IPv6 address, and an IPv6 destination address, both TCP and UDP will will send packets using the IPv4-mapped IPv6 address as the source. Per RFC 6890 (Table 20), IPv4-mapped IPv6 source addresses are not allowed in an IP datagram. The problem can be observed by attempting to connect() either a TCP or UDP socket, or by using sendmsg() with a UDP socket. The patch is intended to correct this issue for all socket types. linux follows the BSD convention that an IPv6 destination address specified as in6addr_any is converted to the loopback address. Currently, neither TCP nor UDP consider the possibility that the source address is an IPv4-mapped IPv6 address, and assume that the appropriate loopback address is ::1. The patch adds a check on whether or not the source address is an IPv4-mapped IPv6 address and then sets the destination address to either ::ffff:127.0.0.1 or ::1, as appropriate. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
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.