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Upon error along the TCP data_ready event path, we have
the following chain of calls:
strp_data_ready()
ovpn_tcp_rcv()
ovpn_peer_del()
ovpn_socket_release()
Since strp_data_ready() may be invoked from softirq context, and
ovpn_socket_release() may sleep, the above sequence may cause a
sleep in atomic context like the following:
BUG: sleeping function called from invalid context at ./ovpn-backports-ovpn-net-next-main-6.15.0-rc5-20250522/drivers/net/ovpn/socket.c:71
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 25, name: ksoftirqd/3
5 locks held by ksoftirqd/3/25:
#0: ffffffe000cd0580 (rcu_read_lock){....}-{1:2}, at: netif_receive_skb+0xb8/0x5b0
OpenVPN/ovpn-backports#1: ffffffe000cd0580 (rcu_read_lock){....}-{1:2}, at: netif_receive_skb+0xb8/0x5b0
OpenVPN/ovpn-backports#2: ffffffe000cd0580 (rcu_read_lock){....}-{1:2}, at: ip_local_deliver_finish+0x66/0x1e0
OpenVPN/ovpn-backports#3: ffffffe003ce9818 (slock-AF_INET/1){+.-.}-{2:2}, at: tcp_v4_rcv+0x156e/0x17a0
OpenVPN/ovpn-backports#4: ffffffe000cd0580 (rcu_read_lock){....}-{1:2}, at: ovpn_tcp_data_ready+0x0/0x1b0 [ovpn]
CPU: 3 PID: 25 Comm: ksoftirqd/3 Not tainted 5.10.104+ #0
Call Trace:
walk_stackframe+0x0/0x1d0
show_stack+0x2e/0x44
dump_stack+0xc2/0x102
___might_sleep+0x29c/0x2b0
__might_sleep+0x62/0xa0
ovpn_socket_release+0x24/0x2d0 [ovpn]
unlock_ovpn+0x6e/0x190 [ovpn]
ovpn_peer_del+0x13c/0x390 [ovpn]
ovpn_tcp_rcv+0x280/0x560 [ovpn]
__strp_recv+0x262/0x940
strp_recv+0x66/0x80
tcp_read_sock+0x122/0x410
strp_data_ready+0x156/0x1f0
ovpn_tcp_data_ready+0x92/0x1b0 [ovpn]
tcp_data_ready+0x6c/0x150
tcp_rcv_established+0xb36/0xc50
tcp_v4_do_rcv+0x25e/0x380
tcp_v4_rcv+0x166a/0x17a0
ip_protocol_deliver_rcu+0x8c/0x250
ip_local_deliver_finish+0xf8/0x1e0
ip_local_deliver+0xc2/0x2d0
ip_rcv+0x1f2/0x330
__netif_receive_skb+0xfc/0x290
netif_receive_skb+0x104/0x5b0
br_pass_frame_up+0x190/0x3f0
br_handle_frame_finish+0x3e2/0x7a0
br_handle_frame+0x750/0xab0
__netif_receive_skb_core.constprop.0+0x4c0/0x17f0
__netif_receive_skb+0xc6/0x290
netif_receive_skb+0x104/0x5b0
xgmac_dma_rx+0x962/0xb40
__napi_poll.constprop.0+0x5a/0x350
net_rx_action+0x1fe/0x4b0
__do_softirq+0x1f8/0x85c
run_ksoftirqd+0x80/0xd0
smpboot_thread_fn+0x1f0/0x3e0
kthread+0x1e6/0x210
ret_from_kernel_thread+0x8/0xc
Fix this issue by postponing the ovpn_peer_del() call to
a scheduled worker, as we already do in ovpn_tcp_send_sock()
for the very same reason.
Fixes: 11851cbd60ea ("ovpn: implement TCP transport")
Reported-by: Qingfang Deng <dqfext@gmail.com>
Closes: https://github.com/OpenVPN/ovpn-net-next/issues/13
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
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Removing a peer while userspace attempts to close its transport
socket triggers a race condition resulting in the following
crash:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000077: 0000 [#1] SMP KASAN
KASAN: null-ptr-deref in range [0x00000000000003b8-0x00000000000003bf]
CPU: 12 UID: 0 PID: 162 Comm: kworker/12:1 Tainted: G O 6.15.0-rc2-00635-g521139ac3840 #272 PREEMPT(full)
Tainted: [O]=OOT_MODULE
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-20240910_120124-localhost 04/01/2014
Workqueue: events ovpn_peer_keepalive_work [ovpn]
RIP: 0010:ovpn_socket_release+0x23c/0x500 [ovpn]
Code: ea 03 80 3c 02 00 0f 85 71 02 00 00 48 b8 00 00 00 00 00 fc ff df 4d 8b 64 24 18 49 8d bc 24 be 03 00 00 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 01 38 d0 7c 08 84 d2 0f 85 30
RSP: 0018:ffffc90000c9fb18 EFLAGS: 00010217
RAX: dffffc0000000000 RBX: ffff8881148d7940 RCX: ffffffff817787bb
RDX: 0000000000000077 RSI: 0000000000000008 RDI: 00000000000003be
RBP: ffffc90000c9fb30 R08: 0000000000000000 R09: fffffbfff0d3e840
R10: ffffffff869f4207 R11: 0000000000000000 R12: 0000000000000000
R13: ffff888115eb9300 R14: ffffc90000c9fbc8 R15: 000000000000000c
FS: 0000000000000000(0000) GS:ffff8882b0151000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f37266b6114 CR3: 00000000054a8000 CR4: 0000000000750ef0
PKRU: 55555554
Call Trace:
<TASK>
unlock_ovpn+0x8b/0xe0 [ovpn]
ovpn_peer_keepalive_work+0xe3/0x540 [ovpn]
? ovpn_peers_free+0x780/0x780 [ovpn]
? lock_acquire+0x56/0x70
? process_one_work+0x888/0x1740
process_one_work+0x933/0x1740
? pwq_dec_nr_in_flight+0x10b0/0x10b0
? move_linked_works+0x12d/0x2c0
? assign_work+0x163/0x270
worker_thread+0x4d6/0xd90
? preempt_count_sub+0x4c/0x70
? process_one_work+0x1740/0x1740
kthread+0x36c/0x710
? trace_preempt_on+0x8c/0x1e0
? kthread_is_per_cpu+0xc0/0xc0
? preempt_count_sub+0x4c/0x70
? _raw_spin_unlock_irq+0x36/0x60
? calculate_sigpending+0x7b/0xa0
? kthread_is_per_cpu+0xc0/0xc0
ret_from_fork+0x3a/0x80
? kthread_is_per_cpu+0xc0/0xc0
ret_from_fork_asm+0x11/0x20
</TASK>
Modules linked in: ovpn(O)
This happens because the peer deletion operation reaches
ovpn_socket_release() while ovpn_sock->sock (struct socket *)
and its sk member (struct sock *) are still both valid.
Here synchronize_rcu() is invoked, after which ovpn_sock->sock->sk
becomes NULL, due to the concurrent socket closing triggered
from userspace.
After having invoked synchronize_rcu(), ovpn_socket_release() will
attempt dereferencing ovpn_sock->sock->sk, triggering the crash
reported above.
The reason for accessing sk is that we need to retrieve its
protocol and continue the cleanup routine accordingly.
This crash can be easily produced by running openvpn userspace in
client mode with `--keepalive 10 20`, while entirely omitting this
option on the server side.
After 20 seconds ovpn will assume the peer (server) to be dead,
will start removing it and will notify userspace. The latter will
receive the notification and close the transport socket, thus
triggering the crash.
To fix the race condition for good, we need to refactor struct ovpn_socket.
Since ovpn is always only interested in the sock->sk member (struct sock *)
we can directly hold a reference to it, raher than accessing it via
its struct socket container.
This means changing "struct socket *ovpn_socket->sock" to
"struct sock *ovpn_socket->sk".
While acquiring a reference to sk, we can increase its refcounter
without affecting the socket close()/destroy() notification
(which we rely on when userspace closes a socket we are using).
By increasing sk's refcounter we know we can dereference it
in ovpn_socket_release() without incurring in any race condition
anymore.
ovpn_socket_release() will ultimately decrease the reference
counter.
Cc: Oleksandr Natalenko <oleksandr@natalenko.name>
Fixes: 11851cbd60ea ("ovpn: implement TCP transport")
Reported-by: Qingfang Deng <dqfext@gmail.com>
Closes: https://github.com/OpenVPN/ovpn-net-next/issues/1
Tested-by: Gert Doering <gert@greenie.muc.de>
Link: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg31575.html
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
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When deconfiguring a UDP-tunnel from a socket, we cannot
call setup_udp_tunnel_sock() with an empty config, because
this helper is expected to be invoked only during setup.
Get rid of the call to setup_udp_tunnel_sock() and just
revert what it did during socket initialization..
Note that the global udp_encap_needed_key and the GRO state
are left untouched: udp_destroy_socket() will eventually
take care of them.
Cc: Sabrina Dubroca <sd@queasysnail.net>
Cc: Oleksandr Natalenko <oleksandr@natalenko.name>
Fixes: ab66abbc769b ("ovpn: implement basic RX path (UDP)")
Reported-by: Paolo Abeni <pabeni@redhat.com>
Closes: https://lore.kernel.org/netdev/1a47ce02-fd42-4761-8697-f3f315011cc6@redhat.com
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
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Depending on the data offset, skb_to_sgvec_nomark() may use
less scatterlist elements than what was forecasted by the
previous call to skb_cow_data().
It specifically happens when 'skbheadlen(skb) < offset', because
in this case we entirely skip the skb's head, which would have
required its own scatterlist element.
For this reason, it doesn't make sense to check that
skb_to_sgvec_nomark() returns the same value as skb_cow_data(),
but we can rather check for errors only, as it happens in
other parts of the kernel.
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
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When debugging a 'no route to host' error it can be beneficial
to know the address of the unreachable destination.
Print it along the debugging text.
While at it, add a missing parenthesis in a different debugging
message inside ovpn_peer_endpoints_update().
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
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The keepalive worker is cancelled before calling
unregister_netdevice_queue(), therefore it will never
hit a situation where the reg_state can be different
than NETDEV_REGISTERED.
For this reason, checking reg_state is useless and the
condition can be removed.
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
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ndo_start_xmit is basically expected to always return NETDEV_TX_OK.
However, in case of error, it was currently returning NET_XMIT_DROP,
which is not a valid netdev_tx_t return value, leading to
misinterpretation.
Change ndo_start_xmit to always return NETDEV_TX_OK to signal back
to the caller that the packet was handled (even if dropped).
Effects of this bug can be seen when sending IPv6 packets having
no peer to forward them to:
$ ip netns exec ovpn-server oping -c20 fd00:abcd:220:201::1
PING fd00:abcd:220:201::1 (fd00:abcd:220:201::1) 56 bytes of data.00:abcd:220:201 :1
ping_send failed: No buffer space available
ping_sendto: No buffer space available
ping_send failed: No buffer space available
ping_sendto: No buffer space available
...
Fixes: c2d950c4672a ("ovpn: add basic interface creation/destruction/management routines")
Reported-by: Gert Doering <gert@greenie.muc.de>
Closes: https://github.com/OpenVPN/ovpn-net-next/issues/5
Tested-by: Gert Doering <gert@greenie.muc.de>
Acked-by: Gert Doering <gert@greenie.muc.de>
Link: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg31591.html
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
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When routing a packet to a LAN behind a peer, ovpn needs to
inspect the route entry that brought the packet there in the
first place.
If this packet is truly routable, the route entry provides the
GW to be used when looking up the VPN peer to send the packet to.
However, the route entry is currently dropped before entering
the ovpn xmit function, because the IFF_XMIT_DST_RELEASE priv_flag
is enabled by default.
Clear the IFF_XMIT_DST_RELEASE flag during interface setup to allow
the route entry (skb's dst) to survive and thus be inspected
by the ovpn routing logic.
Fixes: a3aaef8cd173 ("ovpn: implement peer lookup logic")
Reported-by: Gert Doering <gert@greenie.muc.de>
Closes: https://github.com/OpenVPN/ovpn-net-next/issues/2
Tested-by: Gert Doering <gert@greenie.muc.de>
Acked-by: Gert Doering <gert@greenie.muc.de> # as a primary user
Link: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg31583.html
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
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IPv6 user packets (sent over the tunnel) may be larger than
the outgoing interface MTU after encapsulation.
When this happens ovpn should allow the kernel to fragment
them because they are "locally generated".
To achieve the above, we must set skb->ignore_df = 1
so that ip6_fragment() can be made aware of this decision.
Failing to do so will result in ip6_fragment() dropping
the packet thinking it was "routed".
No change is required in the IPv4 path, because when
calling udp_tunnel_xmit_skb() we already pass the
'df' argument set to 0, therefore the resulting datagram
is allowed to be fragmented if need be.
Fixes: 08857b5ec5d9 ("ovpn: implement basic TX path (UDP)")
Reported-by: Gert Doering <gert@greenie.muc.de>
Closes: https://github.com/OpenVPN/ovpn-net-next/issues/3
Tested-by: Gert Doering <gert@greenie.muc.de>
Acked-by: Gert Doering <gert@greenie.muc.de> # as primary user
Link: https://mail-archive.com/openvpn-devel@lists.sourceforge.net/msg31577.html
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
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Implement support for basic ethtool functionality.
Note that ovpn is a virtual device driver, therefore
various ethtool APIs are just not meaningful and thus
not implemented.
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-22-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Whenever a peer is deleted, send a notification to userspace so that it
can react accordingly.
This is most important when a peer is deleted due to ping timeout,
because it all happens in kernelspace and thus userspace has no direct
way to learn about it.
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-21-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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IV wrap-around is cryptographically dangerous for a number of ciphers,
therefore kill the key and inform userspace (via netlink) should the
IV space go exhausted.
Userspace has two ways of deciding when the key has to be renewed before
exhausting the IV space:
1) time based approach:
after X seconds/minutes userspace generates a new key and sends it
to the kernel. This is based on guestimate and normally default
timer value works well.
2) packet count based approach:
after X packets/bytes userspace generates a new key and sends it to
the kernel. Userspace keeps track of the amount of traffic by
periodically polling GET_PEER and fetching the VPN/LINK stats.
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-20-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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This change introduces the netlink commands needed to add, get, delete
and swap keys for a specific peer.
Userspace is expected to use these commands to create, inspect (non
sensitive data only), destroy and rotate session keys for a specific
peer.
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-19-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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This change introduces the netlink command needed to add, delete and
retrieve/dump known peers. Userspace is expected to use these commands
to handle known peer lifecycles.
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-18-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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In case of UDP links, the local or remote endpoint used to communicate
with a given peer may change without a connection restart.
Add support for learning the new address in case of change.
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-17-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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OpenVPN supports configuring a periodic keepalive packet.
message to allow the remote endpoint detect link failures.
This change implements the keepalive sending and timer expiring logic.
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-16-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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In a multi-peer scenario there are a number of situations when a
specific peer needs to be looked up.
We may want to lookup a peer by:
1. its ID
2. its VPN destination IP
3. its transport IP/port couple
For each of the above, there is a specific routing table referencing all
peers for fast look up.
Case 2. is a bit special in the sense that an outgoing packet may not be
sent to the peer VPN IP directly, but rather to a network behind it. For
this reason we first perform a nexthop lookup in the system routing
table and then we use the retrieved nexthop as peer search key.
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-15-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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With this change an ovpn instance will be able to stay connected to
multiple remote endpoints.
This functionality is strictly required when running ovpn on an
OpenVPN server.
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-14-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Userspace may want to pass the MSG_NOSIGNAL flag to
tcp_sendmsg() in order to avoid generating a SIGPIPE.
To pass this flag down the TCP stack a new skb sending API
accepting a flags argument is introduced.
Cc: Eric Dumazet <edumazet@google.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-13-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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With this change ovpn is allowed to communicate to peers also via TCP.
Parsing of incoming messages is implemented through the strparser API.
Note that ovpn redefines sk_prot and sk_socket->ops for the TCP socket
used to communicate with the peer.
For this reason it needs to access inet6_stream_ops, which is declared
as extern in the IPv6 module, but it is not fully exported.
Therefore this patch is also adding EXPORT_SYMBOL_GPL(inet6_stream_ops)
to net/ipv6/af_inet6.c.
Cc: David Ahern <dsahern@kernel.org>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Simon Horman <horms@kernel.org>
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-11-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Byte/packet counters for in-tunnel and transport streams
are now initialized and updated as needed.
To be exported via netlink.
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-10-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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This change implements encryption/decryption and
encapsulation/decapsulation of OpenVPN packets.
Support for generic crypto state is added along with
a wrapper for the AEAD crypto kernel API.
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-9-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Packets received over the socket are forwarded to the user device.
Implementation is UDP only. TCP will be added by a later patch.
Note: no decryption/decapsulation exists yet, packets are forwarded as
they arrive without much processing.
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-8-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Packets sent over the ovpn interface are processed and transmitted to the
connected peer, if any.
Implementation is UDP only. TCP will be added by a later patch.
Note: no crypto/encapsulation exists yet. Packets are just captured and
sent.
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-7-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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This specific structure is used in the ovpn kernel module
to wrap and carry around a standard kernel socket.
ovpn takes ownership of passed sockets and therefore an ovpn
specific objects is attached to them for status tracking
purposes.
Initially only UDP support is introduced. TCP will come in a later
patch.
Cc: willemdebruijn.kernel@gmail.com
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-6-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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An ovpn_peer object holds the whole status of a remote peer
(regardless whether it is a server or a client).
This includes status for crypto, tx/rx buffers, napi, etc.
Only support for one peer is introduced (P2P mode).
Multi peer support is introduced with a later patch.
Along with the ovpn_peer, also the ovpn_bind object is introcued
as the two are strictly related.
An ovpn_bind object wraps a sockaddr representing the local
coordinates being used to talk to a specific peer.
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-5-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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An ovpn interface configured in MP mode will keep carrier always
on and let the user decide when to bring it administratively up and
down.
This way a MP node (i.e. a server) will keep its interface always
up and running, even when no peer is connected.
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-4-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Add basic infrastructure for handling ovpn interfaces.
Tested-by: Donald Hunter <donald.hunter@gmail.com>
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-3-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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This commit introduces basic netlink support with family
registration/unregistration functionalities and stub pre/post-doit.
More importantly it introduces the YAML uAPI description along
with its auto-generated files:
- include/uapi/linux/ovpn.h
- drivers/net/ovpn/netlink-gen.c
- drivers/net/ovpn/netlink-gen.h
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-2-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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OpenVPN is a userspace software existing since around 2005 that allows
users to create secure tunnels.
So far OpenVPN has implemented all operations in userspace, which
implies several back and forth between kernel and user land in order to
process packets (encapsulate/decapsulate, encrypt/decrypt, rerouting..).
With `ovpn` we intend to move the fast path (data channel) entirely
in kernel space and thus improve user measured throughput over the
tunnel.
`ovpn` is implemented as a simple virtual network device driver, that
can be manipulated by means of the standard RTNL APIs. A device of kind
`ovpn` allows only IPv4/6 traffic and can be of type:
* P2P (peer-to-peer): any packet sent over the interface will be
encapsulated and transmitted to the other side (typical OpenVPN
client or peer-to-peer behaviour);
* P2MP (point-to-multipoint): packets sent over the interface are
transmitted to peers based on existing routes (typical OpenVPN
server behaviour).
After the interface has been created, OpenVPN in userspace can
configure it using a new Netlink API. Specifically it is possible
to manage peers and their keys.
The OpenVPN control channel is multiplexed over the same transport
socket by means of OP codes. Anything that is not DATA_V2 (OpenVPN
OP code for data traffic) is sent to userspace and handled there.
This way the `ovpn` codebase is kept as compact as possible while
focusing on handling data traffic only (fast path).
Any OpenVPN control feature (like cipher negotiation, TLS handshake,
rekeying, etc.) is still fully handled by the userspace process.
When userspace establishes a new connection with a peer, it first
performs the handshake and then passes the socket to the `ovpn` kernel
module, which takes ownership. From this moment on `ovpn` will handle
data traffic for the new peer.
When control packets are received on the link, they are forwarded to
userspace through the same transport socket they were received on, as
userspace is still listening to them.
Some events (like peer deletion) are sent to a Netlink multicast group.
Although it wasn't easy to convince the community, `ovpn` implements
only a limited number of the data-channel features supported by the
userspace program.
Each feature that made it to `ovpn` was attentively vetted to
avoid carrying too much legacy along with us (and to give a clear cut to
old and probalby-not-so-useful features).
Notably, only encryption using AEAD ciphers (specifically
ChaCha20Poly1305 and AES-GCM) was implemented. Supporting any other
cipher out there was not deemed useful.
Both UDP and TCP sockets are supported.
As explained above, in case of P2MP mode, OpenVPN will use the main system
routing table to decide which packet goes to which peer. This implies
that no routing table was re-implemented in the `ovpn` kernel module.
This kernel module can be enabled by selecting the CONFIG_OVPN entry
in the networking drivers section.
NOTE: this first patch introduces the very basic framework only.
Features are then added patch by patch, however, although each patch
will compile and possibly not break at runtime, only after having
applied the full set it is expected to see the ovpn module fully working.
Cc: steffen.klassert@secunet.com
Cc: antony.antony@secunet.com
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/20250415-b4-ovpn-v26-1-577f6097b964@openvpn.net
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Antonio Quartulli