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 */
19 struct 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
mctp_address_unicast(mctp_eid_t eid)41 static inline bool mctp_address_unicast(mctp_eid_t eid)
42 {
43 return eid >= 8 && eid < 255;
44 }
45
mctp_address_broadcast(mctp_eid_t eid)46 static inline bool mctp_address_broadcast(mctp_eid_t eid)
47 {
48 return eid == 255;
49 }
50
mctp_address_null(mctp_eid_t eid)51 static inline bool mctp_address_null(mctp_eid_t eid)
52 {
53 return eid == 0;
54 }
55
mctp_address_matches(mctp_eid_t match,mctp_eid_t eid)56 static inline bool mctp_address_matches(mctp_eid_t match, mctp_eid_t eid)
57 {
58 return match == eid || match == MCTP_ADDR_ANY;
59 }
60
mctp_hdr(struct sk_buff * skb)61 static 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 */
67 struct mctp_sock {
68 struct sock sk;
69
70 /* bind() params */
71 unsigned int bind_net;
72 mctp_eid_t bind_addr;
73 __u8 bind_type;
74
75 /* sendmsg()/recvmsg() uses struct sockaddr_mctp_ext */
76 bool addr_ext;
77
78 /* list of mctp_sk_key, for incoming tag lookup. updates protected
79 * by sk->net->keys_lock
80 */
81 struct hlist_head keys;
82
83 /* mechanism for expiring allocated keys; will release an allocated
84 * tag, and any netdev state for a request/response pairing
85 */
86 struct timer_list key_expiry;
87 };
88
89 /* Key for matching incoming packets to sockets or reassembly contexts.
90 * Packets are matched on (peer EID, local EID, tag).
91 *
92 * Lifetime / locking requirements:
93 *
94 * - individual key data (ie, the struct itself) is protected by key->lock;
95 * changes must be made with that lock held.
96 *
97 * - the lookup fields: peer_addr, local_addr and tag are set before the
98 * key is added to lookup lists, and never updated.
99 *
100 * - A ref to the key must be held (throuh key->refs) if a pointer to the
101 * key is to be accessed after key->lock is released.
102 *
103 * - a mctp_sk_key contains a reference to a struct sock; this is valid
104 * for the life of the key. On sock destruction (through unhash), the key is
105 * removed from lists (see below), and marked invalid.
106 *
107 * - these mctp_sk_keys appear on two lists:
108 * 1) the struct mctp_sock->keys list
109 * 2) the struct netns_mctp->keys list
110 *
111 * presences on these lists requires a (single) refcount to be held; both
112 * lists are updated as a single operation.
113 *
114 * Updates and lookups in either list are performed under the
115 * netns_mctp->keys lock. Lookup functions will need to lock the key and
116 * take a reference before unlocking the keys_lock. Consequently, the list's
117 * keys_lock *cannot* be acquired with the individual key->lock held.
118 *
119 * - a key may have a sk_buff attached as part of an in-progress message
120 * reassembly (->reasm_head). The reasm data is protected by the individual
121 * key->lock.
122 *
123 * - there are two destruction paths for a mctp_sk_key:
124 *
125 * - through socket unhash (see mctp_sk_unhash). This performs the list
126 * removal under keys_lock.
127 *
128 * - where a key is established to receive a reply message: after receiving
129 * the (complete) reply, or during reassembly errors. Here, we clean up
130 * the reassembly context (marking reasm_dead, to prevent another from
131 * starting), and remove the socket from the netns & socket lists.
132 *
133 * - through an expiry timeout, on a per-socket timer
134 */
135 struct mctp_sk_key {
136 unsigned int net;
137 mctp_eid_t peer_addr;
138 mctp_eid_t local_addr; /* MCTP_ADDR_ANY for local owned tags */
139 __u8 tag; /* incoming tag match; invert TO for local */
140
141 /* we hold a ref to sk when set */
142 struct sock *sk;
143
144 /* routing lookup list */
145 struct hlist_node hlist;
146
147 /* per-socket list */
148 struct hlist_node sklist;
149
150 /* lock protects against concurrent updates to the reassembly and
151 * expiry data below.
152 */
153 spinlock_t lock;
154
155 /* Keys are referenced during the output path, which may sleep */
156 refcount_t refs;
157
158 /* incoming fragment reassembly context */
159 struct sk_buff *reasm_head;
160 struct sk_buff **reasm_tailp;
161 bool reasm_dead;
162 u8 last_seq;
163
164 /* key validity */
165 bool valid;
166
167 /* expiry timeout; valid (above) cleared on expiry */
168 unsigned long expiry;
169
170 /* free to use for device flow state tracking. Initialised to
171 * zero on initial key creation
172 */
173 unsigned long dev_flow_state;
174 struct mctp_dev *dev;
175
176 /* a tag allocated with SIOCMCTPALLOCTAG ioctl will not expire
177 * automatically on timeout or response, instead SIOCMCTPDROPTAG
178 * is used.
179 */
180 bool manual_alloc;
181 };
182
183 struct mctp_skb_cb {
184 unsigned int magic;
185 unsigned int net;
186 int ifindex; /* extended/direct addressing if set */
187 mctp_eid_t src;
188 unsigned char halen;
189 unsigned char haddr[MAX_ADDR_LEN];
190 };
191
192 /* skb control-block accessors with a little extra debugging for initial
193 * development.
194 *
195 * TODO: remove checks & mctp_skb_cb->magic; replace callers of __mctp_cb
196 * with mctp_cb().
197 *
198 * __mctp_cb() is only for the initial ingress code; we should see ->magic set
199 * at all times after this.
200 */
__mctp_cb(struct sk_buff * skb)201 static inline struct mctp_skb_cb *__mctp_cb(struct sk_buff *skb)
202 {
203 struct mctp_skb_cb *cb = (void *)skb->cb;
204
205 cb->magic = 0x4d435450;
206 return cb;
207 }
208
mctp_cb(struct sk_buff * skb)209 static inline struct mctp_skb_cb *mctp_cb(struct sk_buff *skb)
210 {
211 struct mctp_skb_cb *cb = (void *)skb->cb;
212
213 BUILD_BUG_ON(sizeof(struct mctp_skb_cb) > sizeof(skb->cb));
214 WARN_ON(cb->magic != 0x4d435450);
215 return (void *)(skb->cb);
216 }
217
218 /* If CONFIG_MCTP_FLOWS, we may add one of these as a SKB extension,
219 * indicating the flow to the device driver.
220 */
221 struct mctp_flow {
222 struct mctp_sk_key *key;
223 };
224
225 /* Route definition.
226 *
227 * These are held in the pernet->mctp.routes list, with RCU protection for
228 * removed routes. We hold a reference to the netdev; routes need to be
229 * dropped on NETDEV_UNREGISTER events.
230 *
231 * Updates to the route table are performed under rtnl; all reads under RCU,
232 * so routes cannot be referenced over a RCU grace period. Specifically: A
233 * caller cannot block between mctp_route_lookup and mctp_route_release()
234 */
235 struct mctp_route {
236 mctp_eid_t min, max;
237
238 unsigned char type;
239 unsigned int mtu;
240 struct mctp_dev *dev;
241 int (*output)(struct mctp_route *route,
242 struct sk_buff *skb);
243
244 struct list_head list;
245 refcount_t refs;
246 struct rcu_head rcu;
247 };
248
249 /* route interfaces */
250 struct mctp_route *mctp_route_lookup(struct net *net, unsigned int dnet,
251 mctp_eid_t daddr);
252
253 /* always takes ownership of skb */
254 int mctp_local_output(struct sock *sk, struct mctp_route *rt,
255 struct sk_buff *skb, mctp_eid_t daddr, u8 req_tag);
256
257 void mctp_key_unref(struct mctp_sk_key *key);
258 struct mctp_sk_key *mctp_alloc_local_tag(struct mctp_sock *msk,
259 unsigned int netid,
260 mctp_eid_t local, mctp_eid_t peer,
261 bool manual, u8 *tagp);
262
263 /* routing <--> device interface */
264 unsigned int mctp_default_net(struct net *net);
265 int mctp_default_net_set(struct net *net, unsigned int index);
266 int mctp_route_add_local(struct mctp_dev *mdev, mctp_eid_t addr);
267 int mctp_route_remove_local(struct mctp_dev *mdev, mctp_eid_t addr);
268 void mctp_route_remove_dev(struct mctp_dev *mdev);
269
270 /* neighbour definitions */
271 enum mctp_neigh_source {
272 MCTP_NEIGH_STATIC,
273 MCTP_NEIGH_DISCOVER,
274 };
275
276 struct mctp_neigh {
277 struct mctp_dev *dev;
278 mctp_eid_t eid;
279 enum mctp_neigh_source source;
280
281 unsigned char ha[MAX_ADDR_LEN];
282
283 struct list_head list;
284 struct rcu_head rcu;
285 };
286
287 int mctp_neigh_init(void);
288 void mctp_neigh_exit(void);
289
290 // ret_hwaddr may be NULL, otherwise must have space for MAX_ADDR_LEN
291 int mctp_neigh_lookup(struct mctp_dev *dev, mctp_eid_t eid,
292 void *ret_hwaddr);
293 void mctp_neigh_remove_dev(struct mctp_dev *mdev);
294
295 int mctp_routes_init(void);
296 void mctp_routes_exit(void);
297
298 int mctp_device_init(void);
299 void mctp_device_exit(void);
300
301 #endif /* __NET_MCTP_H */
302