Re: [PATCH net-next v18 08/25] ovpn: implement basic RX path (UDP)

On 03/02/2025 10:30, Sabrina Dubroca wrote:

2025-01-13, 10:31:27 +0100, Antonio Quartulli wrote:

quoted

+/**
+ * ovpn_opcode_from_skb - extract OP code from skb at specified offset
+ * @skb: the packet to extract the OP code from
+ * @offset: the offset in the data buffer where the OP code is located
+ *
+ * Note: this function assumes that the skb head was pulled enough
+ * to access the first byte.

nit:
                    "first byte"

quoted

+ *
+ * Return: the OP code
+ */
+static inline u8 ovpn_opcode_from_skb(const struct sk_buff *skb, u16 offset)
+{
+	u32 opcode = be32_to_cpu(*(__be32 *)(skb->data + offset));

vs 4 bytes actually read?

Also for ovpn_key_id_from_skb introduced in another patch. I guess
that's a consequence of switching to those FIELD macros.

Your guess is right. I'll fix the comment.

quoted

+/**
+ * ovpn_udp_encap_recv - Start processing a received UDP packet.
+ * @sk: socket over which the packet was received
+ * @skb: the received packet
+ *
+ * If the first byte of the payload is DATA_V2, the packet is further processed,
+ * otherwise it is forwarded to the UDP stack for delivery to user space.

nit: not consistent with the implementation in the case of DATA_V1 packets

Right, I'll extend the comment.

quoted

+ * Return:
+ *  0 if skb was consumed or dropped
+ * >0 if skb should be passed up to userspace as UDP (packet not consumed)
+ * <0 if skb should be resubmitted as proto -N (packet not consumed)
+ */
+static int ovpn_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
+{

[...]

quoted

+	opcode = ovpn_opcode_from_skb(skb, sizeof(struct udphdr));
+	if (unlikely(opcode != OVPN_DATA_V2)) {
+		/* DATA_V1 is not supported */
+		if (opcode == OVPN_DATA_V1)
+			goto drop;

Thanks!


-- 
Antonio Quartulli
OpenVPN Inc.