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 <asm/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 
59 struct clock_identity {
60 	u8 id[8];
61 } __packed;
62 
63 struct port_identity {
64 	struct clock_identity	clock_identity;
65 	__be16			port_number;
66 } __packed;
67 
68 struct 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  */
94 unsigned 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  */
109 struct 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  */
ptp_get_msgtype(const struct ptp_header * hdr,unsigned int type)121 static 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  */
ptp_check_diff8(__be64 old,__be64 new,__wsum oldsum)147 static 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  */
166 static inline
ptp_header_update_correction(struct sk_buff * skb,unsigned int type,struct ptp_header * hdr,s64 correction)167 void 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  */
208 bool ptp_msg_is_sync(struct sk_buff *skb, unsigned int type);
209 
210 void __init ptp_classifier_init(void);
211 #else
ptp_classifier_init(void)212 static inline void ptp_classifier_init(void)
213 {
214 }
ptp_classify_raw(struct sk_buff * skb)215 static inline unsigned int ptp_classify_raw(struct sk_buff *skb)
216 {
217 	return PTP_CLASS_NONE;
218 }
ptp_parse_header(struct sk_buff * skb,unsigned int type)219 static inline struct ptp_header *ptp_parse_header(struct sk_buff *skb,
220 						  unsigned int type)
221 {
222 	return NULL;
223 }
ptp_get_msgtype(const struct ptp_header * hdr,unsigned int type)224 static 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 }
ptp_msg_is_sync(struct sk_buff * skb,unsigned int type)232 static inline bool ptp_msg_is_sync(struct sk_buff *skb, unsigned int type)
233 {
234 	return false;
235 }
236 
237 static inline
ptp_header_update_correction(struct sk_buff * skb,unsigned int type,struct ptp_header * hdr,s64 correction)238 void 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