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Vincent Bernat
c427bfec18
Currently, SO_BINDTODEVICE requires CAP_NET_RAW. This change allows a non-root user to bind a socket to an interface if it is not already bound. This is useful to allow an application to bind itself to a specific VRF for outgoing or incoming connections. Currently, an application wanting to manage connections through several VRF need to be privileged. Previously, IP_UNICAST_IF and IPV6_UNICAST_IF were added for Wine (76e21053b5andc4062dfc42) specifically for use by non-root processes. However, they are restricted to sendmsg() and not usable with TCP. Allowing SO_BINDTODEVICE would allow TCP clients to get the same privilege. As for TCP servers, outside the VRF use case, SO_BINDTODEVICE would only further restrict connections a server could accept. When an application is restricted to a VRF (with `ip vrf exec`), the socket is bound to an interface at creation and therefore, a non-privileged call to SO_BINDTODEVICE to escape the VRF fails. When an application bound a socket to SO_BINDTODEVICE and transmit it to a non-privileged process through a Unix socket, a tentative to change the bound device also fails. Before: >>> import socket >>> s=socket.socket(socket.AF_INET, socket.SOCK_STREAM) >>> s.setsockopt(socket.SOL_SOCKET, socket.SO_BINDTODEVICE, b"dummy0") Traceback (most recent call last): File "<stdin>", line 1, in <module> PermissionError: [Errno 1] Operation not permitted After: >>> import socket >>> s=socket.socket(socket.AF_INET, socket.SOCK_STREAM) >>> s.setsockopt(socket.SOL_SOCKET, socket.SO_BINDTODEVICE, b"dummy0") >>> s.setsockopt(socket.SOL_SOCKET, socket.SO_BINDTODEVICE, b"dummy0") Traceback (most recent call last): File "<stdin>", line 1, in <module> PermissionError: [Errno 1] Operation not permitted Signed-off-by: Vincent Bernat <vincent@bernat.ch> Reviewed-by: David Ahern <dsahern@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
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.