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 <net/net_namespace.h> 15 #include <net/sock.h> 16 17 /* MCTP packet definitions */ 18 struct mctp_hdr { 19 u8 ver; 20 u8 dest; 21 u8 src; 22 u8 flags_seq_tag; 23 }; 24 25 #define MCTP_VER_MIN 1 26 #define MCTP_VER_MAX 1 27 28 /* Definitions for flags_seq_tag field */ 29 #define MCTP_HDR_FLAG_SOM BIT(7) 30 #define MCTP_HDR_FLAG_EOM BIT(6) 31 #define MCTP_HDR_FLAG_TO BIT(3) 32 #define MCTP_HDR_FLAGS GENMASK(5, 3) 33 #define MCTP_HDR_SEQ_SHIFT 4 34 #define MCTP_HDR_SEQ_MASK GENMASK(1, 0) 35 #define MCTP_HDR_TAG_SHIFT 0 36 #define MCTP_HDR_TAG_MASK GENMASK(2, 0) 37 38 #define MCTP_HEADER_MAXLEN 4 39 40 #define MCTP_INITIAL_DEFAULT_NET 1 41 42 static inline bool mctp_address_ok(mctp_eid_t eid) 43 { 44 return eid >= 8 && eid < 255; 45 } 46 47 static inline struct mctp_hdr *mctp_hdr(struct sk_buff *skb) 48 { 49 return (struct mctp_hdr *)skb_network_header(skb); 50 } 51 52 /* socket implementation */ 53 struct mctp_sock { 54 struct sock sk; 55 56 /* bind() params */ 57 int bind_net; 58 mctp_eid_t bind_addr; 59 __u8 bind_type; 60 61 /* list of mctp_sk_key, for incoming tag lookup. updates protected 62 * by sk->net->keys_lock 63 */ 64 struct hlist_head keys; 65 66 /* mechanism for expiring allocated keys; will release an allocated 67 * tag, and any netdev state for a request/response pairing 68 */ 69 struct timer_list key_expiry; 70 }; 71 72 /* Key for matching incoming packets to sockets or reassembly contexts. 73 * Packets are matched on (src,dest,tag). 74 * 75 * Lifetime / locking requirements: 76 * 77 * - individual key data (ie, the struct itself) is protected by key->lock; 78 * changes must be made with that lock held. 79 * 80 * - the lookup fields: peer_addr, local_addr and tag are set before the 81 * key is added to lookup lists, and never updated. 82 * 83 * - A ref to the key must be held (throuh key->refs) if a pointer to the 84 * key is to be accessed after key->lock is released. 85 * 86 * - a mctp_sk_key contains a reference to a struct sock; this is valid 87 * for the life of the key. On sock destruction (through unhash), the key is 88 * removed from lists (see below), and marked invalid. 89 * 90 * - these mctp_sk_keys appear on two lists: 91 * 1) the struct mctp_sock->keys list 92 * 2) the struct netns_mctp->keys list 93 * 94 * presences on these lists requires a (single) refcount to be held; both 95 * lists are updated as a single operation. 96 * 97 * Updates and lookups in either list are performed under the 98 * netns_mctp->keys lock. Lookup functions will need to lock the key and 99 * take a reference before unlocking the keys_lock. Consequently, the list's 100 * keys_lock *cannot* be acquired with the individual key->lock held. 101 * 102 * - a key may have a sk_buff attached as part of an in-progress message 103 * reassembly (->reasm_head). The reasm data is protected by the individual 104 * key->lock. 105 * 106 * - there are two destruction paths for a mctp_sk_key: 107 * 108 * - through socket unhash (see mctp_sk_unhash). This performs the list 109 * removal under keys_lock. 110 * 111 * - where a key is established to receive a reply message: after receiving 112 * the (complete) reply, or during reassembly errors. Here, we clean up 113 * the reassembly context (marking reasm_dead, to prevent another from 114 * starting), and remove the socket from the netns & socket lists. 115 * 116 * - through an expiry timeout, on a per-socket timer 117 */ 118 struct mctp_sk_key { 119 mctp_eid_t peer_addr; 120 mctp_eid_t local_addr; 121 __u8 tag; /* incoming tag match; invert TO for local */ 122 123 /* we hold a ref to sk when set */ 124 struct sock *sk; 125 126 /* routing lookup list */ 127 struct hlist_node hlist; 128 129 /* per-socket list */ 130 struct hlist_node sklist; 131 132 /* lock protects against concurrent updates to the reassembly and 133 * expiry data below. 134 */ 135 spinlock_t lock; 136 137 /* Keys are referenced during the output path, which may sleep */ 138 refcount_t refs; 139 140 /* incoming fragment reassembly context */ 141 struct sk_buff *reasm_head; 142 struct sk_buff **reasm_tailp; 143 bool reasm_dead; 144 u8 last_seq; 145 146 /* key validity */ 147 bool valid; 148 149 /* expiry timeout; valid (above) cleared on expiry */ 150 unsigned long expiry; 151 }; 152 153 struct mctp_skb_cb { 154 unsigned int magic; 155 unsigned int net; 156 mctp_eid_t src; 157 }; 158 159 /* skb control-block accessors with a little extra debugging for initial 160 * development. 161 * 162 * TODO: remove checks & mctp_skb_cb->magic; replace callers of __mctp_cb 163 * with mctp_cb(). 164 * 165 * __mctp_cb() is only for the initial ingress code; we should see ->magic set 166 * at all times after this. 167 */ 168 static inline struct mctp_skb_cb *__mctp_cb(struct sk_buff *skb) 169 { 170 struct mctp_skb_cb *cb = (void *)skb->cb; 171 172 cb->magic = 0x4d435450; 173 return cb; 174 } 175 176 static inline struct mctp_skb_cb *mctp_cb(struct sk_buff *skb) 177 { 178 struct mctp_skb_cb *cb = (void *)skb->cb; 179 180 WARN_ON(cb->magic != 0x4d435450); 181 return (void *)(skb->cb); 182 } 183 184 /* Route definition. 185 * 186 * These are held in the pernet->mctp.routes list, with RCU protection for 187 * removed routes. We hold a reference to the netdev; routes need to be 188 * dropped on NETDEV_UNREGISTER events. 189 * 190 * Updates to the route table are performed under rtnl; all reads under RCU, 191 * so routes cannot be referenced over a RCU grace period. Specifically: A 192 * caller cannot block between mctp_route_lookup and passing the route to 193 * mctp_do_route. 194 */ 195 struct mctp_route { 196 mctp_eid_t min, max; 197 198 struct mctp_dev *dev; 199 unsigned int mtu; 200 unsigned char type; 201 int (*output)(struct mctp_route *route, 202 struct sk_buff *skb); 203 204 struct list_head list; 205 refcount_t refs; 206 struct rcu_head rcu; 207 }; 208 209 /* route interfaces */ 210 struct mctp_route *mctp_route_lookup(struct net *net, unsigned int dnet, 211 mctp_eid_t daddr); 212 213 int mctp_do_route(struct mctp_route *rt, struct sk_buff *skb); 214 215 int mctp_local_output(struct sock *sk, struct mctp_route *rt, 216 struct sk_buff *skb, mctp_eid_t daddr, u8 req_tag); 217 218 void mctp_key_unref(struct mctp_sk_key *key); 219 220 /* routing <--> device interface */ 221 unsigned int mctp_default_net(struct net *net); 222 int mctp_default_net_set(struct net *net, unsigned int index); 223 int mctp_route_add_local(struct mctp_dev *mdev, mctp_eid_t addr); 224 int mctp_route_remove_local(struct mctp_dev *mdev, mctp_eid_t addr); 225 void mctp_route_remove_dev(struct mctp_dev *mdev); 226 227 /* neighbour definitions */ 228 enum mctp_neigh_source { 229 MCTP_NEIGH_STATIC, 230 MCTP_NEIGH_DISCOVER, 231 }; 232 233 struct mctp_neigh { 234 struct mctp_dev *dev; 235 mctp_eid_t eid; 236 enum mctp_neigh_source source; 237 238 unsigned char ha[MAX_ADDR_LEN]; 239 240 struct list_head list; 241 struct rcu_head rcu; 242 }; 243 244 int mctp_neigh_init(void); 245 void mctp_neigh_exit(void); 246 247 // ret_hwaddr may be NULL, otherwise must have space for MAX_ADDR_LEN 248 int mctp_neigh_lookup(struct mctp_dev *dev, mctp_eid_t eid, 249 void *ret_hwaddr); 250 void mctp_neigh_remove_dev(struct mctp_dev *mdev); 251 252 int mctp_routes_init(void); 253 void mctp_routes_exit(void); 254 255 void mctp_device_init(void); 256 void mctp_device_exit(void); 257 258 #endif /* __NET_MCTP_H */ 259