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The current netlink API for WireGuard does not directly support removal
of allowed ips from a peer. A user can remove an allowed ip from a peer
in one of two ways:
1. By using the WGPEER_F_REPLACE_ALLOWEDIPS flag and providing a new
list of allowed ips which omits the allowed ip that is to be removed.
2. By reassigning an allowed ip to a "dummy" peer then removing that
peer with WGPEER_F_REMOVE_ME.
With the first approach, the driver completely rebuilds the allowed ip
list for a peer. If my current configuration is such that a peer has
allowed ips 192.168.0.2 and 192.168.0.3 and I want to remove 192.168.0.2
the actual transition looks like this.
[192.168.0.2, 192.168.0.3] <-- Initial state
[] <-- Step 1: Allowed ips removed for peer
[192.168.0.3] <-- Step 2: Allowed ips added back for peer
This is true even if the allowed ip list is small and the update does
not need to be batched into multiple WG_CMD_SET_DEVICE requests, as the
removal and subsequent addition of ips is non-atomic within a single
request. Consequently, wg_allowedips_lookup_dst and
wg_allowedips_lookup_src may return NULL while reconfiguring a peer even
for packets bound for ips a user did not intend to remove leading to
unintended interruptions in connectivity. This presents in userspace as
failed calls to sendto and sendmsg for UDP sockets. In my case, I ran
netperf while repeatedly reconfiguring the allowed ips for a peer with
wg.
/usr/local/bin/netperf -H 10.102.73.72 -l 10m -t UDP_STREAM -- -R 1 -m 1024
send_data: data send error: No route to host (errno 113)
netperf: send_omni: send_data failed: No route to host
While this may not be of particular concern for environments where peers
and allowed ips are mostly static, systems like Cilium manage peers and
allowed ips in a dynamic environment where peers (i.e. Kubernetes nodes)
and allowed ips (i.e. pods running on those nodes) can frequently
change making WGPEER_F_REPLACE_ALLOWEDIPS problematic.
The second approach avoids any possible connectivity interruptions
but is hacky and less direct, requiring the creation of a temporary
peer just to dispose of an allowed ip.
Introduce a new flag called WGALLOWEDIP_F_REMOVE_ME which in the same
way that WGPEER_F_REMOVE_ME allows a user to remove a single peer from
a WireGuard device's configuration allows a user to remove an ip from a
peer's set of allowed ips. This enables incremental updates to a
device's configuration without any connectivity blips or messy
workarounds.
A corresponding patch for wg extends the existing `wg set` interface to
leverage this feature.
$ wg set wg0 peer <PUBKEY> allowed-ips +192.168.88.0/24,-192.168.0.1/32
When '+' or '-' is prepended to any ip in the list, wg clears
WGPEER_F_REPLACE_ALLOWEDIPS and sets the WGALLOWEDIP_F_REMOVE_ME flag on
any ip prefixed with '-'.
Signed-off-by: Jordan Rife <jordan@jrife.io>
[Jason: minor style nits, fixes to selftest, bump of wireguard-tools version]
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Link: https://patch.msgid.link/20250521212707.1767879-5-Jason@zx2c4.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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WireGuard is a layer 3 secure networking tunnel made specifically for
the kernel, that aims to be much simpler and easier to audit than IPsec.
Extensive documentation and description of the protocol and
considerations, along with formal proofs of the cryptography, are
available at:
* https://www.wireguard.com/
* https://www.wireguard.com/papers/wireguard.pdf
This commit implements WireGuard as a simple network device driver,
accessible in the usual RTNL way used by virtual network drivers. It
makes use of the udp_tunnel APIs, GRO, GSO, NAPI, and the usual set of
networking subsystem APIs. It has a somewhat novel multicore queueing
system designed for maximum throughput and minimal latency of encryption
operations, but it is implemented modestly using workqueues and NAPI.
Configuration is done via generic Netlink, and following a review from
the Netlink maintainer a year ago, several high profile userspace tools
have already implemented the API.
This commit also comes with several different tests, both in-kernel
tests and out-of-kernel tests based on network namespaces, taking profit
of the fact that sockets used by WireGuard intentionally stay in the
namespace the WireGuard interface was originally created, exactly like
the semantics of userspace tun devices. See wireguard.com/netns/ for
pictures and examples.
The source code is fairly short, but rather than combining everything
into a single file, WireGuard is developed as cleanly separable files,
making auditing and comprehension easier. Things are laid out as
follows:
* noise.[ch], cookie.[ch], messages.h: These implement the bulk of the
cryptographic aspects of the protocol, and are mostly data-only in
nature, taking in buffers of bytes and spitting out buffers of
bytes. They also handle reference counting for their various shared
pieces of data, like keys and key lists.
* ratelimiter.[ch]: Used as an integral part of cookie.[ch] for
ratelimiting certain types of cryptographic operations in accordance
with particular WireGuard semantics.
* allowedips.[ch], peerlookup.[ch]: The main lookup structures of
WireGuard, the former being trie-like with particular semantics, an
integral part of the design of the protocol, and the latter just
being nice helper functions around the various hashtables we use.
* device.[ch]: Implementation of functions for the netdevice and for
rtnl, responsible for maintaining the life of a given interface and
wiring it up to the rest of WireGuard.
* peer.[ch]: Each interface has a list of peers, with helper functions
available here for creation, destruction, and reference counting.
* socket.[ch]: Implementation of functions related to udp_socket and
the general set of kernel socket APIs, for sending and receiving
ciphertext UDP packets, and taking care of WireGuard-specific sticky
socket routing semantics for the automatic roaming.
* netlink.[ch]: Userspace API entry point for configuring WireGuard
peers and devices. The API has been implemented by several userspace
tools and network management utility, and the WireGuard project
distributes the basic wg(8) tool.
* queueing.[ch]: Shared function on the rx and tx path for handling
the various queues used in the multicore algorithms.
* send.c: Handles encrypting outgoing packets in parallel on
multiple cores, before sending them in order on a single core, via
workqueues and ring buffers. Also handles sending handshake and cookie
messages as part of the protocol, in parallel.
* receive.c: Handles decrypting incoming packets in parallel on
multiple cores, before passing them off in order to be ingested via
the rest of the networking subsystem with GRO via the typical NAPI
poll function. Also handles receiving handshake and cookie messages
as part of the protocol, in parallel.
* timers.[ch]: Uses the timer wheel to implement protocol particular
event timeouts, and gives a set of very simple event-driven entry
point functions for callers.
* main.c, version.h: Initialization and deinitialization of the module.
* selftest/*.h: Runtime unit tests for some of the most security
sensitive functions.
* tools/testing/selftests/wireguard/netns.sh: Aforementioned testing
script using network namespaces.
This commit aims to be as self-contained as possible, implementing
WireGuard as a standalone module not needing much special handling or
coordination from the network subsystem. I expect for future
optimizations to the network stack to positively improve WireGuard, and
vice-versa, but for the time being, this exists as intentionally
standalone.
We introduce a menu option for CONFIG_WIREGUARD, as well as providing a
verbose debug log and self-tests via CONFIG_WIREGUARD_DEBUG.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: David Miller <davem@davemloft.net>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: linux-crypto@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
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