Re: [PATCH net-next v9 04/23] ovpn: add basic interface creation/destruction/management routines

Antonio Quartulli
2024-10-16T14:24:04Z

On 16/10/2024 10:27, Jiri Pirko wrote:
> Wed, Oct 16, 2024 at 03:03:04AM CEST, antonio@openvpn.net wrote:
>> Add basic infrastructure for handling ovpn interfaces.
>>
>> Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
>> ---
>> drivers/net/ovpn/main.c | 115 ++++++++++++++++++++++++++++++++++++++++--
>> drivers/net/ovpn/main.h | 7 +++
>> drivers/net/ovpn/ovpnstruct.h | 8 +++
>> drivers/net/ovpn/packet.h | 40 +++++++++++++++
>> include/uapi/linux/if_link.h | 15 ++++++
>> 5 files changed, 180 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/net/ovpn/main.c b/drivers/net/ovpn/main.c
>> index d5bdb0055f4dd3a6e32dc6e792bed1e7fd59e101..eead7677b8239eb3c48bb26ca95492d88512b8d4 100644
>> --- a/drivers/net/ovpn/main.c
>> +++ b/drivers/net/ovpn/main.c
>> @@ -10,18 +10,52 @@
>> #include <linux/genetlink.h>
>> #include <linux/module.h>
>> #include <linux/netdevice.h>
>> +#include <linux/inetdevice.h>
>> +#include <net/ip.h>
>> #include <net/rtnetlink.h>
>> -#include <uapi/linux/ovpn.h>
>> +#include <uapi/linux/if_arp.h>
>>
>> #include "ovpnstruct.h"
>> #include "main.h"
>> #include "netlink.h"
>> #include "io.h"
>> +#include "packet.h"
>>
>> /* Driver info */
>> #define DRV_DESCRIPTION "OpenVPN data channel offload (ovpn)"
>> #define DRV_COPYRIGHT "(C) 2020-2024 OpenVPN, Inc."
>>
>> +static void ovpn_struct_free(struct net_device *net)
>> +{
>> +}
>> +
>> +static int ovpn_net_open(struct net_device *dev)
>> +{
>> + netif_tx_start_all_queues(dev);
>> + return 0;
>> +}
>> +
>> +static int ovpn_net_stop(struct net_device *dev)
>> +{
>> + netif_tx_stop_all_queues(dev);
>> + return 0;
>> +}
>> +
>> +static const struct net_device_ops ovpn_netdev_ops = {
>> + .ndo_open = ovpn_net_open,
>> + .ndo_stop = ovpn_net_stop,
>> + .ndo_start_xmit = ovpn_net_xmit,
>> +};
>> +
>> +static const struct device_type ovpn_type = {
>> + .name = OVPN_FAMILY_NAME,
>> +};
>> +
>> +static const struct nla_policy ovpn_policy[IFLA_OVPN_MAX + 1] = {
>> + [IFLA_OVPN_MODE] = NLA_POLICY_RANGE(NLA_U8, OVPN_MODE_P2P,
>> + OVPN_MODE_MP),
>> +};
>> +
>> /**
>> * ovpn_dev_is_valid - check if the netdevice is of type 'ovpn'
>> * @dev: the interface to check
>> @@ -33,16 +67,76 @@ bool ovpn_dev_is_valid(const struct net_device *dev)
>> return dev->netdev_ops->ndo_start_xmit == ovpn_net_xmit;
>> }
>>
>> +static void ovpn_setup(struct net_device *dev)
>> +{
>> + /* compute the overhead considering AEAD encryption */
>> + const int overhead = sizeof(u32) + NONCE_WIRE_SIZE + 16 +
>> + sizeof(struct udphdr) +
>> + max(sizeof(struct ipv6hdr), sizeof(struct iphdr));
>> +
>> + netdev_features_t feat = NETIF_F_SG | NETIF_F_HW_CSUM | NETIF_F_RXCSUM |
>> + NETIF_F_GSO | NETIF_F_GSO_SOFTWARE |
>> + NETIF_F_HIGHDMA;
>> +
>> + dev->needs_free_netdev = true;
>> +
>> + dev->pcpu_stat_type = NETDEV_PCPU_STAT_TSTATS;
>> +
>> + dev->netdev_ops = &ovpn_netdev_ops;
>> +
>> + dev->priv_destructor = ovpn_struct_free;
>> +
>> + dev->hard_header_len = 0;
>> + dev->addr_len = 0;
>> + dev->mtu = ETH_DATA_LEN - overhead;
>> + dev->min_mtu = IPV4_MIN_MTU;
>> + dev->max_mtu = IP_MAX_MTU - overhead;
>> +
>> + dev->type = ARPHRD_NONE;
>> + dev->flags = IFF_POINTOPOINT | IFF_NOARP;
>> + dev->priv_flags |= IFF_NO_QUEUE;
>> +
>> + dev->lltx = true;
>> + dev->features |= feat;
>> + dev->hw_features |= feat;
>> + dev->hw_enc_features |= feat;
>> +
>> + dev->needed_headroom = OVPN_HEAD_ROOM;
>> + dev->needed_tailroom = OVPN_MAX_PADDING;
>> +
>> + SET_NETDEV_DEVTYPE(dev, &ovpn_type);
>> +}
>> +
>> static int ovpn_newlink(struct net *src_net, struct net_device *dev,
>> struct nlattr *tb[], struct nlattr *data[],
>> struct netlink_ext_ack *extack)
>> {
>> - return -EOPNOTSUPP;
>> + struct ovpn_struct *ovpn = netdev_priv(dev);
>> + enum ovpn_mode mode = OVPN_MODE_P2P;
>> +
>> + if (data && data[IFLA_OVPN_MODE]) {
>> + mode = nla_get_u8(data[IFLA_OVPN_MODE]);
>
> Some sanity check perhaps? "validate" op is here for that purpose.

Isn't the parsing happening here enough

https://elixir.bootlin.com/linux/v6.12-rc3/source/net/core/rtnetlink.c#L3659

The IFINFO_DATA is parsed using the policy I provided (which comes with
limits for the mode attribute).

Or am I misreading the code and I still need to provide an
implementation for .validate?

Regards,

>
>
>> + netdev_dbg(dev, "setting device mode: %u\n", mode);
>> + }
>> +
>> + ovpn->dev = dev;
>> + ovpn->mode = mode;
>> +
>> + /* turn carrier explicitly off after registration, this way state is
>> + * clearly defined
>> + */
>> + netif_carrier_off(dev);
>> +
>> + return register_netdevice(dev);
>
> [...]

--
Antonio Quartulli
OpenVPN Inc.