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 ver field */ 30 #define MCTP_HDR_VER_MASK GENMASK(3, 0) 31 32 /* Definitions for flags_seq_tag field */ 33 #define MCTP_HDR_FLAG_SOM BIT(7) 34 #define MCTP_HDR_FLAG_EOM BIT(6) 35 #define MCTP_HDR_FLAG_TO BIT(3) 36 #define MCTP_HDR_FLAGS GENMASK(5, 3) 37 #define MCTP_HDR_SEQ_SHIFT 4 38 #define MCTP_HDR_SEQ_MASK GENMASK(1, 0) 39 #define MCTP_HDR_TAG_SHIFT 0 40 #define MCTP_HDR_TAG_MASK GENMASK(2, 0) 41 42 #define MCTP_INITIAL_DEFAULT_NET 1 43 44 static inline bool mctp_address_unicast(mctp_eid_t eid) 45 { 46 return eid >= 8 && eid < 255; 47 } 48 49 static inline bool mctp_address_broadcast(mctp_eid_t eid) 50 { 51 return eid == 255; 52 } 53 54 static inline bool mctp_address_null(mctp_eid_t eid) 55 { 56 return eid == 0; 57 } 58 59 static inline bool mctp_address_matches(mctp_eid_t match, mctp_eid_t eid) 60 { 61 return match == eid || match == MCTP_ADDR_ANY; 62 } 63 64 static inline struct mctp_hdr *mctp_hdr(struct sk_buff *skb) 65 { 66 return (struct mctp_hdr *)skb_network_header(skb); 67 } 68 69 /* socket implementation */ 70 struct mctp_sock { 71 struct sock sk; 72 73 /* bind() params */ 74 unsigned int bind_net; 75 mctp_eid_t bind_local_addr; 76 mctp_eid_t bind_peer_addr; 77 unsigned int bind_peer_net; 78 bool bind_peer_set; 79 __u8 bind_type; 80 81 /* sendmsg()/recvmsg() uses struct sockaddr_mctp_ext */ 82 bool addr_ext; 83 84 /* list of mctp_sk_key, for incoming tag lookup. updates protected 85 * by sk->net->keys_lock 86 */ 87 struct hlist_head keys; 88 89 /* mechanism for expiring allocated keys; will release an allocated 90 * tag, and any netdev state for a request/response pairing 91 */ 92 struct timer_list key_expiry; 93 }; 94 95 /* Key for matching incoming packets to sockets or reassembly contexts. 96 * Packets are matched on (peer EID, local EID, tag). 97 * 98 * Lifetime / locking requirements: 99 * 100 * - individual key data (ie, the struct itself) is protected by key->lock; 101 * changes must be made with that lock held. 102 * 103 * - the lookup fields: peer_addr, local_addr and tag are set before the 104 * key is added to lookup lists, and never updated. 105 * 106 * - A ref to the key must be held (throuh key->refs) if a pointer to the 107 * key is to be accessed after key->lock is released. 108 * 109 * - a mctp_sk_key contains a reference to a struct sock; this is valid 110 * for the life of the key. On sock destruction (through unhash), the key is 111 * removed from lists (see below), and marked invalid. 112 * 113 * - these mctp_sk_keys appear on two lists: 114 * 1) the struct mctp_sock->keys list 115 * 2) the struct netns_mctp->keys list 116 * 117 * presences on these lists requires a (single) refcount to be held; both 118 * lists are updated as a single operation. 119 * 120 * Updates and lookups in either list are performed under the 121 * netns_mctp->keys lock. Lookup functions will need to lock the key and 122 * take a reference before unlocking the keys_lock. Consequently, the list's 123 * keys_lock *cannot* be acquired with the individual key->lock held. 124 * 125 * - a key may have a sk_buff attached as part of an in-progress message 126 * reassembly (->reasm_head). The reasm data is protected by the individual 127 * key->lock. 128 * 129 * - there are two destruction paths for a mctp_sk_key: 130 * 131 * - through socket unhash (see mctp_sk_unhash). This performs the list 132 * removal under keys_lock. 133 * 134 * - where a key is established to receive a reply message: after receiving 135 * the (complete) reply, or during reassembly errors. Here, we clean up 136 * the reassembly context (marking reasm_dead, to prevent another from 137 * starting), and remove the socket from the netns & socket lists. 138 * 139 * - through an expiry timeout, on a per-socket timer 140 */ 141 struct mctp_sk_key { 142 unsigned int net; 143 mctp_eid_t peer_addr; 144 mctp_eid_t local_addr; /* MCTP_ADDR_ANY for local owned tags */ 145 __u8 tag; /* incoming tag match; invert TO for local */ 146 147 /* we hold a ref to sk when set */ 148 struct sock *sk; 149 150 /* routing lookup list */ 151 struct hlist_node hlist; 152 153 /* per-socket list */ 154 struct hlist_node sklist; 155 156 /* lock protects against concurrent updates to the reassembly and 157 * expiry data below. 158 */ 159 spinlock_t lock; 160 161 /* Keys are referenced during the output path, which may sleep */ 162 refcount_t refs; 163 164 /* incoming fragment reassembly context */ 165 struct sk_buff *reasm_head; 166 struct sk_buff **reasm_tailp; 167 bool reasm_dead; 168 u8 last_seq; 169 170 /* key validity */ 171 bool valid; 172 173 /* expiry timeout; valid (above) cleared on expiry */ 174 unsigned long expiry; 175 176 /* free to use for device flow state tracking. Initialised to 177 * zero on initial key creation 178 */ 179 unsigned long dev_flow_state; 180 struct mctp_dev *dev; 181 182 /* a tag allocated with SIOCMCTPALLOCTAG ioctl will not expire 183 * automatically on timeout or response, instead SIOCMCTPDROPTAG 184 * is used. 185 */ 186 bool manual_alloc; 187 }; 188 189 struct mctp_skb_cb { 190 unsigned int magic; 191 unsigned int net; 192 /* fields below provide extended addressing for ingress to recvmsg() */ 193 int ifindex; 194 unsigned char halen; 195 unsigned char haddr[MAX_ADDR_LEN]; 196 }; 197 198 /* skb control-block accessors with a little extra debugging for initial 199 * development. 200 * 201 * TODO: remove checks & mctp_skb_cb->magic; replace callers of __mctp_cb 202 * with mctp_cb(). 203 * 204 * __mctp_cb() is only for the initial ingress code; we should see ->magic set 205 * at all times after this. 206 */ 207 static inline struct mctp_skb_cb *__mctp_cb(struct sk_buff *skb) 208 { 209 struct mctp_skb_cb *cb = (void *)skb->cb; 210 211 cb->magic = 0x4d435450; 212 return cb; 213 } 214 215 static inline struct mctp_skb_cb *mctp_cb(struct sk_buff *skb) 216 { 217 struct mctp_skb_cb *cb = (void *)skb->cb; 218 219 BUILD_BUG_ON(sizeof(struct mctp_skb_cb) > sizeof(skb->cb)); 220 WARN_ON(cb->magic != 0x4d435450); 221 return cb; 222 } 223 224 /* If CONFIG_MCTP_FLOWS, we may add one of these as a SKB extension, 225 * indicating the flow to the device driver. 226 */ 227 struct mctp_flow { 228 struct mctp_sk_key *key; 229 }; 230 231 struct mctp_dst; 232 233 /* Route definition. 234 * 235 * These are held in the pernet->mctp.routes list, with RCU protection for 236 * removed routes. We hold a reference to the netdev; routes need to be 237 * dropped on NETDEV_UNREGISTER events. 238 * 239 * Updates to the route table are performed under rtnl; all reads under RCU, 240 * so routes cannot be referenced over a RCU grace period. 241 */ 242 struct mctp_route { 243 mctp_eid_t min, max; 244 245 unsigned char type; 246 247 unsigned int mtu; 248 249 enum { 250 MCTP_ROUTE_DIRECT, 251 MCTP_ROUTE_GATEWAY, 252 } dst_type; 253 union { 254 struct mctp_dev *dev; 255 struct mctp_fq_addr gateway; 256 }; 257 258 int (*output)(struct mctp_dst *dst, 259 struct sk_buff *skb); 260 261 struct list_head list; 262 refcount_t refs; 263 struct rcu_head rcu; 264 }; 265 266 /* Route lookup result: dst. Represents the results of a routing decision, 267 * but is only held over the individual routing operation. 268 * 269 * Will typically be stored on the caller stack, and must be released after 270 * usage. 271 */ 272 struct mctp_dst { 273 struct mctp_dev *dev; 274 unsigned int mtu; 275 mctp_eid_t nexthop; 276 mctp_eid_t saddr; 277 278 /* set for direct addressing */ 279 unsigned char halen; 280 unsigned char haddr[MAX_ADDR_LEN]; 281 282 int (*output)(struct mctp_dst *dst, struct sk_buff *skb); 283 }; 284 285 int mctp_dst_from_extaddr(struct mctp_dst *dst, struct net *net, int ifindex, 286 unsigned char halen, const unsigned char *haddr); 287 288 /* route interfaces */ 289 int mctp_route_lookup(struct net *net, unsigned int dnet, 290 mctp_eid_t daddr, struct mctp_dst *dst); 291 292 void mctp_dst_release(struct mctp_dst *dst); 293 294 /* always takes ownership of skb */ 295 int mctp_local_output(struct sock *sk, struct mctp_dst *dst, 296 struct sk_buff *skb, mctp_eid_t daddr, u8 req_tag); 297 298 void mctp_key_unref(struct mctp_sk_key *key); 299 struct mctp_sk_key *mctp_alloc_local_tag(struct mctp_sock *msk, 300 unsigned int netid, 301 mctp_eid_t local, mctp_eid_t peer, 302 bool manual, u8 *tagp); 303 304 /* routing <--> device interface */ 305 unsigned int mctp_default_net(struct net *net); 306 int mctp_default_net_set(struct net *net, unsigned int index); 307 int mctp_route_add_local(struct mctp_dev *mdev, mctp_eid_t addr); 308 int mctp_route_remove_local(struct mctp_dev *mdev, mctp_eid_t addr); 309 void mctp_route_remove_dev(struct mctp_dev *mdev); 310 311 /* neighbour definitions */ 312 enum mctp_neigh_source { 313 MCTP_NEIGH_STATIC, 314 MCTP_NEIGH_DISCOVER, 315 }; 316 317 struct mctp_neigh { 318 struct mctp_dev *dev; 319 mctp_eid_t eid; 320 enum mctp_neigh_source source; 321 322 unsigned char ha[MAX_ADDR_LEN]; 323 324 struct list_head list; 325 struct rcu_head rcu; 326 }; 327 328 int mctp_neigh_init(void); 329 void mctp_neigh_exit(void); 330 331 // ret_hwaddr may be NULL, otherwise must have space for MAX_ADDR_LEN 332 int mctp_neigh_lookup(struct mctp_dev *dev, mctp_eid_t eid, 333 void *ret_hwaddr); 334 void mctp_neigh_remove_dev(struct mctp_dev *mdev); 335 336 int mctp_routes_init(void); 337 void mctp_routes_exit(void); 338 339 int mctp_device_init(void); 340 void mctp_device_exit(void); 341 342 /* MCTP IDs and Codes from DMTF specification 343 * "DSP0239 Management Component Transport Protocol (MCTP) IDs and Codes" 344 * https://www.dmtf.org/sites/default/files/standards/documents/DSP0239_1.11.1.pdf 345 */ 346 enum mctp_phys_binding { 347 MCTP_PHYS_BINDING_UNSPEC = 0x00, 348 MCTP_PHYS_BINDING_SMBUS = 0x01, 349 MCTP_PHYS_BINDING_PCIE_VDM = 0x02, 350 MCTP_PHYS_BINDING_USB = 0x03, 351 MCTP_PHYS_BINDING_KCS = 0x04, 352 MCTP_PHYS_BINDING_SERIAL = 0x05, 353 MCTP_PHYS_BINDING_I3C = 0x06, 354 MCTP_PHYS_BINDING_MMBI = 0x07, 355 MCTP_PHYS_BINDING_PCC = 0x08, 356 MCTP_PHYS_BINDING_UCIE = 0x09, 357 MCTP_PHYS_BINDING_VENDOR = 0xFF, 358 }; 359 360 #endif /* __NET_MCTP_H */ 361