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_HEADER_MAXLEN 4 40 41 #define MCTP_INITIAL_DEFAULT_NET 1 42 43 static inline bool mctp_address_unicast(mctp_eid_t eid) 44 { 45 return eid >= 8 && eid < 255; 46 } 47 48 static inline bool mctp_address_broadcast(mctp_eid_t eid) 49 { 50 return eid == 255; 51 } 52 53 static inline bool mctp_address_null(mctp_eid_t eid) 54 { 55 return eid == 0; 56 } 57 58 static inline bool mctp_address_matches(mctp_eid_t match, mctp_eid_t eid) 59 { 60 return match == eid || match == MCTP_ADDR_ANY; 61 } 62 63 static inline struct mctp_hdr *mctp_hdr(struct sk_buff *skb) 64 { 65 return (struct mctp_hdr *)skb_network_header(skb); 66 } 67 68 /* socket implementation */ 69 struct mctp_sock { 70 struct sock sk; 71 72 /* bind() params */ 73 unsigned int bind_net; 74 mctp_eid_t bind_addr; 75 __u8 bind_type; 76 77 /* sendmsg()/recvmsg() uses struct sockaddr_mctp_ext */ 78 bool addr_ext; 79 80 /* list of mctp_sk_key, for incoming tag lookup. updates protected 81 * by sk->net->keys_lock 82 */ 83 struct hlist_head keys; 84 85 /* mechanism for expiring allocated keys; will release an allocated 86 * tag, and any netdev state for a request/response pairing 87 */ 88 struct timer_list key_expiry; 89 }; 90 91 /* Key for matching incoming packets to sockets or reassembly contexts. 92 * Packets are matched on (src,dest,tag). 93 * 94 * Lifetime / locking requirements: 95 * 96 * - individual key data (ie, the struct itself) is protected by key->lock; 97 * changes must be made with that lock held. 98 * 99 * - the lookup fields: peer_addr, local_addr and tag are set before the 100 * key is added to lookup lists, and never updated. 101 * 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. 104 * 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. 108 * 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 112 * 113 * presences on these lists requires a (single) refcount to be held; both 114 * lists are updated as a single operation. 115 * 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. 120 * 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 123 * key->lock. 124 * 125 * - there are two destruction paths for a mctp_sk_key: 126 * 127 * - through socket unhash (see mctp_sk_unhash). This performs the list 128 * removal under keys_lock. 129 * 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. 134 * 135 * - through an expiry timeout, on a per-socket timer 136 */ 137 struct mctp_sk_key { 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 */ 141 142 /* we hold a ref to sk when set */ 143 struct sock *sk; 144 145 /* routing lookup list */ 146 struct hlist_node hlist; 147 148 /* per-socket list */ 149 struct hlist_node sklist; 150 151 /* lock protects against concurrent updates to the reassembly and 152 * expiry data below. 153 */ 154 spinlock_t lock; 155 156 /* Keys are referenced during the output path, which may sleep */ 157 refcount_t refs; 158 159 /* incoming fragment reassembly context */ 160 struct sk_buff *reasm_head; 161 struct sk_buff **reasm_tailp; 162 bool reasm_dead; 163 u8 last_seq; 164 165 /* key validity */ 166 bool valid; 167 168 /* expiry timeout; valid (above) cleared on expiry */ 169 unsigned long expiry; 170 171 /* free to use for device flow state tracking. Initialised to 172 * zero on initial key creation 173 */ 174 unsigned long dev_flow_state; 175 struct mctp_dev *dev; 176 177 /* a tag allocated with SIOCMCTPALLOCTAG ioctl will not expire 178 * automatically on timeout or response, instead SIOCMCTPDROPTAG 179 * is used. 180 */ 181 bool manual_alloc; 182 }; 183 184 struct mctp_skb_cb { 185 unsigned int magic; 186 unsigned int net; 187 int ifindex; /* extended/direct addressing if set */ 188 mctp_eid_t src; 189 unsigned char halen; 190 unsigned char haddr[MAX_ADDR_LEN]; 191 }; 192 193 /* skb control-block accessors with a little extra debugging for initial 194 * development. 195 * 196 * TODO: remove checks & mctp_skb_cb->magic; replace callers of __mctp_cb 197 * with mctp_cb(). 198 * 199 * __mctp_cb() is only for the initial ingress code; we should see ->magic set 200 * at all times after this. 201 */ 202 static inline struct mctp_skb_cb *__mctp_cb(struct sk_buff *skb) 203 { 204 struct mctp_skb_cb *cb = (void *)skb->cb; 205 206 cb->magic = 0x4d435450; 207 return cb; 208 } 209 210 static inline struct mctp_skb_cb *mctp_cb(struct sk_buff *skb) 211 { 212 struct mctp_skb_cb *cb = (void *)skb->cb; 213 214 BUILD_BUG_ON(sizeof(struct mctp_skb_cb) > sizeof(skb->cb)); 215 WARN_ON(cb->magic != 0x4d435450); 216 return (void *)(skb->cb); 217 } 218 219 /* If CONFIG_MCTP_FLOWS, we may add one of these as a SKB extension, 220 * indicating the flow to the device driver. 221 */ 222 struct mctp_flow { 223 struct mctp_sk_key *key; 224 }; 225 226 /* Route definition. 227 * 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. 231 * 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() 235 */ 236 struct mctp_route { 237 mctp_eid_t min, max; 238 239 struct mctp_dev *dev; 240 unsigned int mtu; 241 unsigned char type; 242 int (*output)(struct mctp_route *route, 243 struct sk_buff *skb); 244 245 struct list_head list; 246 refcount_t refs; 247 struct rcu_head rcu; 248 }; 249 250 /* route interfaces */ 251 struct mctp_route *mctp_route_lookup(struct net *net, unsigned int dnet, 252 mctp_eid_t daddr); 253 254 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 mctp_eid_t daddr, mctp_eid_t saddr, 260 bool manual, u8 *tagp); 261 262 /* 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); 268 269 /* neighbour definitions */ 270 enum mctp_neigh_source { 271 MCTP_NEIGH_STATIC, 272 MCTP_NEIGH_DISCOVER, 273 }; 274 275 struct mctp_neigh { 276 struct mctp_dev *dev; 277 mctp_eid_t eid; 278 enum mctp_neigh_source source; 279 280 unsigned char ha[MAX_ADDR_LEN]; 281 282 struct list_head list; 283 struct rcu_head rcu; 284 }; 285 286 int mctp_neigh_init(void); 287 void mctp_neigh_exit(void); 288 289 // 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, 291 void *ret_hwaddr); 292 void mctp_neigh_remove_dev(struct mctp_dev *mdev); 293 294 int mctp_routes_init(void); 295 void mctp_routes_exit(void); 296 297 void mctp_device_init(void); 298 void mctp_device_exit(void); 299 300 #endif /* __NET_MCTP_H */ 301