ptp_classify.h

  1/* SPDX-License-Identifier: GPL-2.0-or-later */
  2/*
  3 * PTP 1588 support
  4 *
  5 * This file implements a BPF that recognizes PTP event messages.
  6 *
  7 * Copyright (C) 2010 OMICRON electronics GmbH
  8 */
  9
 10#ifndef _PTP_CLASSIFY_H_
 11#define _PTP_CLASSIFY_H_
 12
 13#include <linux/unaligned.h>
 14#include <linux/ip.h>
 15#include <linux/ktime.h>
 16#include <linux/skbuff.h>
 17#include <linux/udp.h>
 18#include <net/checksum.h>
 19
 20#define PTP_CLASS_NONE  0x00 /* not a PTP event message */
 21#define PTP_CLASS_V1    0x01 /* protocol version 1 */
 22#define PTP_CLASS_V2    0x02 /* protocol version 2 */
 23#define PTP_CLASS_VMASK 0x0f /* max protocol version is 15 */
 24#define PTP_CLASS_IPV4  0x10 /* event in an IPV4 UDP packet */
 25#define PTP_CLASS_IPV6  0x20 /* event in an IPV6 UDP packet */
 26#define PTP_CLASS_L2    0x40 /* event in a L2 packet */
 27#define PTP_CLASS_PMASK	0x70 /* mask for the packet type field */
 28#define PTP_CLASS_VLAN	0x80 /* event in a VLAN tagged packet */
 29
 30#define PTP_CLASS_V1_IPV4 (PTP_CLASS_V1 | PTP_CLASS_IPV4)
 31#define PTP_CLASS_V1_IPV6 (PTP_CLASS_V1 | PTP_CLASS_IPV6) /* probably DNE */
 32#define PTP_CLASS_V2_IPV4 (PTP_CLASS_V2 | PTP_CLASS_IPV4)
 33#define PTP_CLASS_V2_IPV6 (PTP_CLASS_V2 | PTP_CLASS_IPV6)
 34#define PTP_CLASS_V2_L2   (PTP_CLASS_V2 | PTP_CLASS_L2)
 35#define PTP_CLASS_V2_VLAN (PTP_CLASS_V2 | PTP_CLASS_VLAN)
 36#define PTP_CLASS_L4      (PTP_CLASS_IPV4 | PTP_CLASS_IPV6)
 37
 38#define PTP_MSGTYPE_SYNC        0x0
 39#define PTP_MSGTYPE_DELAY_REQ   0x1
 40#define PTP_MSGTYPE_PDELAY_REQ  0x2
 41#define PTP_MSGTYPE_PDELAY_RESP 0x3
 42
 43#define PTP_EV_PORT 319
 44#define PTP_GEN_PORT 320
 45#define PTP_GEN_BIT 0x08 /* indicates general message, if set in message type */
 46
 47#define OFF_PTP_SOURCE_UUID	22 /* PTPv1 only */
 48#define OFF_PTP_SEQUENCE_ID	30
 49
 50/* PTP header flag fields */
 51#define PTP_FLAG_TWOSTEP	BIT(1)
 52
 53/* Below defines should actually be removed at some point in time. */
 54#define IP6_HLEN	40
 55#define UDP_HLEN	8
 56#define OFF_IHL		14
 57#define IPV4_HLEN(data) (((struct iphdr *)(data + OFF_IHL))->ihl << 2)
 58
 59struct clock_identity {
 60	u8 id[8];
 61} __packed;
 62
 63struct port_identity {
 64	struct clock_identity	clock_identity;
 65	__be16			port_number;
 66} __packed;
 67
 68struct ptp_header {
 69	u8			tsmt;  /* transportSpecific | messageType */
 70	u8			ver;   /* reserved          | versionPTP  */
 71	__be16			message_length;
 72	u8			domain_number;
 73	u8			reserved1;
 74	u8			flag_field[2];
 75	__be64			correction;
 76	__be32			reserved2;
 77	struct port_identity	source_port_identity;
 78	__be16			sequence_id;
 79	u8			control;
 80	u8			log_message_interval;
 81} __packed;
 82
 83#if defined(CONFIG_NET_PTP_CLASSIFY)
 84/**
 85 * ptp_classify_raw - classify a PTP packet
 86 * @skb: buffer
 87 *
 88 * Runs a minimal BPF dissector to classify a network packet to
 89 * determine the PTP class. In case the skb does not contain any
 90 * PTP protocol data, PTP_CLASS_NONE will be returned, otherwise
 91 * PTP_CLASS_V1_IPV{4,6}, PTP_CLASS_V2_IPV{4,6} or
 92 * PTP_CLASS_V2_{L2,VLAN}, depending on the packet content.
 93 */
 94unsigned int ptp_classify_raw(const struct sk_buff *skb);
 95
 96/**
 97 * ptp_parse_header - Get pointer to the PTP v2 header
 98 * @skb: packet buffer
 99 * @type: type of the packet (see ptp_classify_raw())
100 *
101 * This function takes care of the VLAN, UDP, IPv4 and IPv6 headers. The length
102 * is checked.
103 *
104 * Note, internally skb_mac_header() is used. Make sure that the @skb is
105 * initialized accordingly.
106 *
107 * Return: Pointer to the ptp v2 header or NULL if not found
108 */
109struct ptp_header *ptp_parse_header(struct sk_buff *skb, unsigned int type);
110
111/**
112 * ptp_get_msgtype - Extract ptp message type from given header
113 * @hdr: ptp header
114 * @type: type of the packet (see ptp_classify_raw())
115 *
116 * This function returns the message type for a given ptp header. It takes care
117 * of the different ptp header versions (v1 or v2).
118 *
119 * Return: The message type
120 */
121static inline u8 ptp_get_msgtype(const struct ptp_header *hdr,
122				 unsigned int type)
123{
124	u8 msgtype;
125
126	if (unlikely(type & PTP_CLASS_V1)) {
127		/* msg type is located at the control field for ptp v1 */
128		msgtype = hdr->control;
129	} else {
130		msgtype = hdr->tsmt & 0x0f;
131	}
132
133	return msgtype;
134}
135
136/**
137 * ptp_check_diff8 - Computes new checksum (when altering a 64-bit field)
138 * @old: old field value
139 * @new: new field value
140 * @oldsum: previous checksum
141 *
142 * This function can be used to calculate a new checksum when only a single
143 * field is changed. Similar as ip_vs_check_diff*() in ip_vs.h.
144 *
145 * Return: Updated checksum
146 */
147static inline __wsum ptp_check_diff8(__be64 old, __be64 new, __wsum oldsum)
148{
149	__be64 diff[2] = { ~old, new };
150
151	return csum_partial(diff, sizeof(diff), oldsum);
152}
153
154/**
155 * ptp_header_update_correction - Update PTP header's correction field
156 * @skb: packet buffer
157 * @type: type of the packet (see ptp_classify_raw())
158 * @hdr: ptp header
159 * @correction: new correction value
160 *
161 * This updates the correction field of a PTP header and updates the UDP
162 * checksum (if UDP is used as transport). It is needed for hardware capable of
163 * one-step P2P that does not already modify the correction field of Pdelay_Req
164 * event messages on ingress.
165 */
166static inline
167void ptp_header_update_correction(struct sk_buff *skb, unsigned int type,
168				  struct ptp_header *hdr, s64 correction)
169{
170	__be64 correction_old;
171	struct udphdr *uhdr;
172
173	/* previous correction value is required for checksum update. */
174	memcpy(&correction_old,  &hdr->correction, sizeof(correction_old));
175
176	/* write new correction value */
177	put_unaligned_be64((u64)correction, &hdr->correction);
178
179	switch (type & PTP_CLASS_PMASK) {
180	case PTP_CLASS_IPV4:
181	case PTP_CLASS_IPV6:
182		/* locate udp header */
183		uhdr = (struct udphdr *)((char *)hdr - sizeof(struct udphdr));
184		break;
185	default:
186		return;
187	}
188
189	/* update checksum */
190	uhdr->check = csum_fold(ptp_check_diff8(correction_old,
191						hdr->correction,
192						~csum_unfold(uhdr->check)));
193	if (!uhdr->check)
194		uhdr->check = CSUM_MANGLED_0;
195
196	skb->ip_summed = CHECKSUM_NONE;
197}
198
199/**
200 * ptp_msg_is_sync - Evaluates whether the given skb is a PTP Sync message
201 * @skb: packet buffer
202 * @type: type of the packet (see ptp_classify_raw())
203 *
204 * This function evaluates whether the given skb is a PTP Sync message.
205 *
206 * Return: true if sync message, false otherwise
207 */
208bool ptp_msg_is_sync(struct sk_buff *skb, unsigned int type);
209
210void __init ptp_classifier_init(void);
211#else
212static inline void ptp_classifier_init(void)
213{
214}
215static inline unsigned int ptp_classify_raw(struct sk_buff *skb)
216{
217	return PTP_CLASS_NONE;
218}
219static inline struct ptp_header *ptp_parse_header(struct sk_buff *skb,
220						  unsigned int type)
221{
222	return NULL;
223}
224static inline u8 ptp_get_msgtype(const struct ptp_header *hdr,
225				 unsigned int type)
226{
227	/* The return is meaningless. The stub function would not be
228	 * executed since no available header from ptp_parse_header.
229	 */
230	return PTP_MSGTYPE_SYNC;
231}
232static inline bool ptp_msg_is_sync(struct sk_buff *skb, unsigned int type)
233{
234	return false;
235}
236
237static inline
238void ptp_header_update_correction(struct sk_buff *skb, unsigned int type,
239				  struct ptp_header *hdr, s64 correction)
240{
241}
242#endif
243#endif /* _PTP_CLASSIFY_H_ */