1 /* SPDX-License-Identifier: GPL-2.0 */
3 * Management Component Transport Protocol (MCTP)
5 * Copyright (c) 2021 Code Construct
6 * Copyright (c) 2021 Google
12 #include <linux/bits.h>
13 #include <linux/mctp.h>
14 #include <linux/netdevice.h>
15 #include <net/net_namespace.h>
18 /* MCTP packet definitions */
26 #define MCTP_VER_MIN 1
27 #define MCTP_VER_MAX 1
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)
39 #define MCTP_HEADER_MAXLEN 4
41 #define MCTP_INITIAL_DEFAULT_NET 1
43 static inline bool mctp_address_unicast(mctp_eid_t eid)
45 return eid >= 8 && eid < 255;
48 static inline bool mctp_address_broadcast(mctp_eid_t eid)
53 static inline bool mctp_address_null(mctp_eid_t eid)
58 static inline bool mctp_address_matches(mctp_eid_t match, mctp_eid_t eid)
60 return match == eid || match == MCTP_ADDR_ANY;
63 static inline struct mctp_hdr *mctp_hdr(struct sk_buff *skb)
65 return (struct mctp_hdr *)skb_network_header(skb);
68 /* socket implementation */
73 unsigned int bind_net;
77 /* sendmsg()/recvmsg() uses struct sockaddr_mctp_ext */
80 /* list of mctp_sk_key, for incoming tag lookup. updates protected
81 * by sk->net->keys_lock
83 struct hlist_head keys;
85 /* mechanism for expiring allocated keys; will release an allocated
86 * tag, and any netdev state for a request/response pairing
88 struct timer_list key_expiry;
91 /* Key for matching incoming packets to sockets or reassembly contexts.
92 * Packets are matched on (src,dest,tag).
94 * Lifetime / locking requirements:
96 * - individual key data (ie, the struct itself) is protected by key->lock;
97 * changes must be made with that lock held.
99 * - the lookup fields: peer_addr, local_addr and tag are set before the
100 * key is added to lookup lists, and never updated.
102 * - A ref to the key must be held (throuh key->refs) if a pointer to the
103 * key is to be accessed after key->lock is released.
105 * - a mctp_sk_key contains a reference to a struct sock; this is valid
106 * for the life of the key. On sock destruction (through unhash), the key is
107 * removed from lists (see below), and marked invalid.
109 * - these mctp_sk_keys appear on two lists:
110 * 1) the struct mctp_sock->keys list
111 * 2) the struct netns_mctp->keys list
113 * presences on these lists requires a (single) refcount to be held; both
114 * lists are updated as a single operation.
116 * Updates and lookups in either list are performed under the
117 * netns_mctp->keys lock. Lookup functions will need to lock the key and
118 * take a reference before unlocking the keys_lock. Consequently, the list's
119 * keys_lock *cannot* be acquired with the individual key->lock held.
121 * - a key may have a sk_buff attached as part of an in-progress message
122 * reassembly (->reasm_head). The reasm data is protected by the individual
125 * - there are two destruction paths for a mctp_sk_key:
127 * - through socket unhash (see mctp_sk_unhash). This performs the list
128 * removal under keys_lock.
130 * - where a key is established to receive a reply message: after receiving
131 * the (complete) reply, or during reassembly errors. Here, we clean up
132 * the reassembly context (marking reasm_dead, to prevent another from
133 * starting), and remove the socket from the netns & socket lists.
135 * - through an expiry timeout, on a per-socket timer
138 mctp_eid_t peer_addr;
139 mctp_eid_t local_addr; /* MCTP_ADDR_ANY for local owned tags */
140 __u8 tag; /* incoming tag match; invert TO for local */
142 /* we hold a ref to sk when set */
145 /* routing lookup list */
146 struct hlist_node hlist;
148 /* per-socket list */
149 struct hlist_node sklist;
151 /* lock protects against concurrent updates to the reassembly and
156 /* Keys are referenced during the output path, which may sleep */
159 /* incoming fragment reassembly context */
160 struct sk_buff *reasm_head;
161 struct sk_buff **reasm_tailp;
168 /* expiry timeout; valid (above) cleared on expiry */
169 unsigned long expiry;
171 /* free to use for device flow state tracking. Initialised to
172 * zero on initial key creation
174 unsigned long dev_flow_state;
175 struct mctp_dev *dev;
177 /* a tag allocated with SIOCMCTPALLOCTAG ioctl will not expire
178 * automatically on timeout or response, instead SIOCMCTPDROPTAG
187 int ifindex; /* extended/direct addressing if set */
190 unsigned char haddr[MAX_ADDR_LEN];
193 /* skb control-block accessors with a little extra debugging for initial
196 * TODO: remove checks & mctp_skb_cb->magic; replace callers of __mctp_cb
199 * __mctp_cb() is only for the initial ingress code; we should see ->magic set
200 * at all times after this.
202 static inline struct mctp_skb_cb *__mctp_cb(struct sk_buff *skb)
204 struct mctp_skb_cb *cb = (void *)skb->cb;
206 cb->magic = 0x4d435450;
210 static inline struct mctp_skb_cb *mctp_cb(struct sk_buff *skb)
212 struct mctp_skb_cb *cb = (void *)skb->cb;
214 BUILD_BUG_ON(sizeof(struct mctp_skb_cb) > sizeof(skb->cb));
215 WARN_ON(cb->magic != 0x4d435450);
216 return (void *)(skb->cb);
219 /* If CONFIG_MCTP_FLOWS, we may add one of these as a SKB extension,
220 * indicating the flow to the device driver.
223 struct mctp_sk_key *key;
228 * These are held in the pernet->mctp.routes list, with RCU protection for
229 * removed routes. We hold a reference to the netdev; routes need to be
230 * dropped on NETDEV_UNREGISTER events.
232 * Updates to the route table are performed under rtnl; all reads under RCU,
233 * so routes cannot be referenced over a RCU grace period. Specifically: A
234 * caller cannot block between mctp_route_lookup and mctp_route_release()
239 struct mctp_dev *dev;
242 int (*output)(struct mctp_route *route,
243 struct sk_buff *skb);
245 struct list_head list;
250 /* route interfaces */
251 struct mctp_route *mctp_route_lookup(struct net *net, unsigned int dnet,
254 int mctp_local_output(struct sock *sk, struct mctp_route *rt,
255 struct sk_buff *skb, mctp_eid_t daddr, u8 req_tag);
257 void mctp_key_unref(struct mctp_sk_key *key);
258 struct mctp_sk_key *mctp_alloc_local_tag(struct mctp_sock *msk,
259 mctp_eid_t daddr, mctp_eid_t saddr,
260 bool manual, u8 *tagp);
262 /* routing <--> device interface */
263 unsigned int mctp_default_net(struct net *net);
264 int mctp_default_net_set(struct net *net, unsigned int index);
265 int mctp_route_add_local(struct mctp_dev *mdev, mctp_eid_t addr);
266 int mctp_route_remove_local(struct mctp_dev *mdev, mctp_eid_t addr);
267 void mctp_route_remove_dev(struct mctp_dev *mdev);
269 /* neighbour definitions */
270 enum mctp_neigh_source {
276 struct mctp_dev *dev;
278 enum mctp_neigh_source source;
280 unsigned char ha[MAX_ADDR_LEN];
282 struct list_head list;
286 int mctp_neigh_init(void);
287 void mctp_neigh_exit(void);
289 // ret_hwaddr may be NULL, otherwise must have space for MAX_ADDR_LEN
290 int mctp_neigh_lookup(struct mctp_dev *dev, mctp_eid_t eid,
292 void mctp_neigh_remove_dev(struct mctp_dev *mdev);
294 int mctp_routes_init(void);
295 void mctp_routes_exit(void);
297 void mctp_device_init(void);
298 void mctp_device_exit(void);
300 #endif /* __NET_MCTP_H */