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(buff: diff, len: sizeof(diff), sum: 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(val: (u64)correction, p: &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(csum: ptp_check_diff8(old: correction_old,
191 new: hdr->correction,
192 oldsum: ~csum_unfold(n: 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_ */
244

source code of linux/include/linux/ptp_classify.h

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