1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Management Component Transport Protocol (MCTP)
4 *
5 * Copyright (c) 2021 Code Construct
6 * Copyright (c) 2021 Google
7 */
8
9#ifndef __NET_MCTP_H
10#define __NET_MCTP_H
11
12#include <linux/bits.h>
13#include <linux/mctp.h>
14#include <linux/netdevice.h>
15#include <net/net_namespace.h>
16#include <net/sock.h>
17
18/* MCTP packet definitions */
19struct mctp_hdr {
20 u8 ver;
21 u8 dest;
22 u8 src;
23 u8 flags_seq_tag;
24};
25
26#define MCTP_VER_MIN 1
27#define MCTP_VER_MAX 1
28
29/* Definitions for flags_seq_tag field */
30#define MCTP_HDR_FLAG_SOM BIT(7)
31#define MCTP_HDR_FLAG_EOM BIT(6)
32#define MCTP_HDR_FLAG_TO BIT(3)
33#define MCTP_HDR_FLAGS GENMASK(5, 3)
34#define MCTP_HDR_SEQ_SHIFT 4
35#define MCTP_HDR_SEQ_MASK GENMASK(1, 0)
36#define MCTP_HDR_TAG_SHIFT 0
37#define MCTP_HDR_TAG_MASK GENMASK(2, 0)
38
39#define MCTP_INITIAL_DEFAULT_NET 1
40
41static inline bool mctp_address_unicast(mctp_eid_t eid)
42{
43 return eid >= 8 && eid < 255;
44}
45
46static inline bool mctp_address_broadcast(mctp_eid_t eid)
47{
48 return eid == 255;
49}
50
51static inline bool mctp_address_null(mctp_eid_t eid)
52{
53 return eid == 0;
54}
55
56static inline bool mctp_address_matches(mctp_eid_t match, mctp_eid_t eid)
57{
58 return match == eid || match == MCTP_ADDR_ANY;
59}
60
61static inline struct mctp_hdr *mctp_hdr(struct sk_buff *skb)
62{
63 return (struct mctp_hdr *)skb_network_header(skb);
64}
65
66/* socket implementation */
67struct mctp_sock {
68 struct sock sk;
69
70 /* bind() params */
71 unsigned int bind_net;
72 mctp_eid_t bind_local_addr;
73 mctp_eid_t bind_peer_addr;
74 unsigned int bind_peer_net;
75 bool bind_peer_set;
76 __u8 bind_type;
77
78 /* sendmsg()/recvmsg() uses struct sockaddr_mctp_ext */
79 bool addr_ext;
80
81 /* list of mctp_sk_key, for incoming tag lookup. updates protected
82 * by sk->net->keys_lock
83 */
84 struct hlist_head keys;
85
86 /* mechanism for expiring allocated keys; will release an allocated
87 * tag, and any netdev state for a request/response pairing
88 */
89 struct timer_list key_expiry;
90};
91
92/* Key for matching incoming packets to sockets or reassembly contexts.
93 * Packets are matched on (peer EID, local EID, tag).
94 *
95 * Lifetime / locking requirements:
96 *
97 * - individual key data (ie, the struct itself) is protected by key->lock;
98 * changes must be made with that lock held.
99 *
100 * - the lookup fields: peer_addr, local_addr and tag are set before the
101 * key is added to lookup lists, and never updated.
102 *
103 * - A ref to the key must be held (throuh key->refs) if a pointer to the
104 * key is to be accessed after key->lock is released.
105 *
106 * - a mctp_sk_key contains a reference to a struct sock; this is valid
107 * for the life of the key. On sock destruction (through unhash), the key is
108 * removed from lists (see below), and marked invalid.
109 *
110 * - these mctp_sk_keys appear on two lists:
111 * 1) the struct mctp_sock->keys list
112 * 2) the struct netns_mctp->keys list
113 *
114 * presences on these lists requires a (single) refcount to be held; both
115 * lists are updated as a single operation.
116 *
117 * Updates and lookups in either list are performed under the
118 * netns_mctp->keys lock. Lookup functions will need to lock the key and
119 * take a reference before unlocking the keys_lock. Consequently, the list's
120 * keys_lock *cannot* be acquired with the individual key->lock held.
121 *
122 * - a key may have a sk_buff attached as part of an in-progress message
123 * reassembly (->reasm_head). The reasm data is protected by the individual
124 * key->lock.
125 *
126 * - there are two destruction paths for a mctp_sk_key:
127 *
128 * - through socket unhash (see mctp_sk_unhash). This performs the list
129 * removal under keys_lock.
130 *
131 * - where a key is established to receive a reply message: after receiving
132 * the (complete) reply, or during reassembly errors. Here, we clean up
133 * the reassembly context (marking reasm_dead, to prevent another from
134 * starting), and remove the socket from the netns & socket lists.
135 *
136 * - through an expiry timeout, on a per-socket timer
137 */
138struct mctp_sk_key {
139 unsigned int net;
140 mctp_eid_t peer_addr;
141 mctp_eid_t local_addr; /* MCTP_ADDR_ANY for local owned tags */
142 __u8 tag; /* incoming tag match; invert TO for local */
143
144 /* we hold a ref to sk when set */
145 struct sock *sk;
146
147 /* routing lookup list */
148 struct hlist_node hlist;
149
150 /* per-socket list */
151 struct hlist_node sklist;
152
153 /* lock protects against concurrent updates to the reassembly and
154 * expiry data below.
155 */
156 spinlock_t lock;
157
158 /* Keys are referenced during the output path, which may sleep */
159 refcount_t refs;
160
161 /* incoming fragment reassembly context */
162 struct sk_buff *reasm_head;
163 struct sk_buff **reasm_tailp;
164 bool reasm_dead;
165 u8 last_seq;
166
167 /* key validity */
168 bool valid;
169
170 /* expiry timeout; valid (above) cleared on expiry */
171 unsigned long expiry;
172
173 /* free to use for device flow state tracking. Initialised to
174 * zero on initial key creation
175 */
176 unsigned long dev_flow_state;
177 struct mctp_dev *dev;
178
179 /* a tag allocated with SIOCMCTPALLOCTAG ioctl will not expire
180 * automatically on timeout or response, instead SIOCMCTPDROPTAG
181 * is used.
182 */
183 bool manual_alloc;
184};
185
186struct mctp_skb_cb {
187 unsigned int magic;
188 unsigned int net;
189 /* fields below provide extended addressing for ingress to recvmsg() */
190 int ifindex;
191 unsigned char halen;
192 unsigned char haddr[MAX_ADDR_LEN];
193};
194
195/* skb control-block accessors with a little extra debugging for initial
196 * development.
197 *
198 * TODO: remove checks & mctp_skb_cb->magic; replace callers of __mctp_cb
199 * with mctp_cb().
200 *
201 * __mctp_cb() is only for the initial ingress code; we should see ->magic set
202 * at all times after this.
203 */
204static inline struct mctp_skb_cb *__mctp_cb(struct sk_buff *skb)
205{
206 struct mctp_skb_cb *cb = (void *)skb->cb;
207
208 cb->magic = 0x4d435450;
209 return cb;
210}
211
212static inline struct mctp_skb_cb *mctp_cb(struct sk_buff *skb)
213{
214 struct mctp_skb_cb *cb = (void *)skb->cb;
215
216 BUILD_BUG_ON(sizeof(struct mctp_skb_cb) > sizeof(skb->cb));
217 WARN_ON(cb->magic != 0x4d435450);
218 return cb;
219}
220
221/* If CONFIG_MCTP_FLOWS, we may add one of these as a SKB extension,
222 * indicating the flow to the device driver.
223 */
224struct mctp_flow {
225 struct mctp_sk_key *key;
226};
227
228struct mctp_dst;
229
230/* Route definition.
231 *
232 * These are held in the pernet->mctp.routes list, with RCU protection for
233 * removed routes. We hold a reference to the netdev; routes need to be
234 * dropped on NETDEV_UNREGISTER events.
235 *
236 * Updates to the route table are performed under rtnl; all reads under RCU,
237 * so routes cannot be referenced over a RCU grace period.
238 */
239struct mctp_route {
240 mctp_eid_t min, max;
241
242 unsigned char type;
243
244 unsigned int mtu;
245
246 enum {
247 MCTP_ROUTE_DIRECT,
248 MCTP_ROUTE_GATEWAY,
249 } dst_type;
250 union {
251 struct mctp_dev *dev;
252 struct mctp_fq_addr gateway;
253 };
254
255 int (*output)(struct mctp_dst *dst,
256 struct sk_buff *skb);
257
258 struct list_head list;
259 refcount_t refs;
260 struct rcu_head rcu;
261};
262
263/* Route lookup result: dst. Represents the results of a routing decision,
264 * but is only held over the individual routing operation.
265 *
266 * Will typically be stored on the caller stack, and must be released after
267 * usage.
268 */
269struct mctp_dst {
270 struct mctp_dev *dev;
271 unsigned int mtu;
272 mctp_eid_t nexthop;
273
274 /* set for direct addressing */
275 unsigned char halen;
276 unsigned char haddr[MAX_ADDR_LEN];
277
278 int (*output)(struct mctp_dst *dst, struct sk_buff *skb);
279};
280
281int mctp_dst_from_extaddr(struct mctp_dst *dst, struct net *net, int ifindex,
282 unsigned char halen, const unsigned char *haddr);
283
284/* route interfaces */
285int mctp_route_lookup(struct net *net, unsigned int dnet,
286 mctp_eid_t daddr, struct mctp_dst *dst);
287
288void mctp_dst_release(struct mctp_dst *dst);
289
290/* always takes ownership of skb */
291int mctp_local_output(struct sock *sk, struct mctp_dst *dst,
292 struct sk_buff *skb, mctp_eid_t daddr, u8 req_tag);
293
294void mctp_key_unref(struct mctp_sk_key *key);
295struct mctp_sk_key *mctp_alloc_local_tag(struct mctp_sock *msk,
296 unsigned int netid,
297 mctp_eid_t local, mctp_eid_t peer,
298 bool manual, u8 *tagp);
299
300/* routing <--> device interface */
301unsigned int mctp_default_net(struct net *net);
302int mctp_default_net_set(struct net *net, unsigned int index);
303int mctp_route_add_local(struct mctp_dev *mdev, mctp_eid_t addr);
304int mctp_route_remove_local(struct mctp_dev *mdev, mctp_eid_t addr);
305void mctp_route_remove_dev(struct mctp_dev *mdev);
306
307/* neighbour definitions */
308enum mctp_neigh_source {
309 MCTP_NEIGH_STATIC,
310 MCTP_NEIGH_DISCOVER,
311};
312
313struct mctp_neigh {
314 struct mctp_dev *dev;
315 mctp_eid_t eid;
316 enum mctp_neigh_source source;
317
318 unsigned char ha[MAX_ADDR_LEN];
319
320 struct list_head list;
321 struct rcu_head rcu;
322};
323
324int mctp_neigh_init(void);
325void mctp_neigh_exit(void);
326
327// ret_hwaddr may be NULL, otherwise must have space for MAX_ADDR_LEN
328int mctp_neigh_lookup(struct mctp_dev *dev, mctp_eid_t eid,
329 void *ret_hwaddr);
330void mctp_neigh_remove_dev(struct mctp_dev *mdev);
331
332int mctp_routes_init(void);
333void mctp_routes_exit(void);
334
335int mctp_device_init(void);
336void mctp_device_exit(void);
337
338/* MCTP IDs and Codes from DMTF specification
339 * "DSP0239 Management Component Transport Protocol (MCTP) IDs and Codes"
340 * https://www.dmtf.org/sites/default/files/standards/documents/DSP0239_1.11.1.pdf
341 */
342enum mctp_phys_binding {
343 MCTP_PHYS_BINDING_UNSPEC = 0x00,
344 MCTP_PHYS_BINDING_SMBUS = 0x01,
345 MCTP_PHYS_BINDING_PCIE_VDM = 0x02,
346 MCTP_PHYS_BINDING_USB = 0x03,
347 MCTP_PHYS_BINDING_KCS = 0x04,
348 MCTP_PHYS_BINDING_SERIAL = 0x05,
349 MCTP_PHYS_BINDING_I3C = 0x06,
350 MCTP_PHYS_BINDING_MMBI = 0x07,
351 MCTP_PHYS_BINDING_PCC = 0x08,
352 MCTP_PHYS_BINDING_UCIE = 0x09,
353 MCTP_PHYS_BINDING_VENDOR = 0xFF,
354};
355
356#endif /* __NET_MCTP_H */
357