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 (src,dest,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 mctp_eid_t peer_addr; 137 mctp_eid_t local_addr; /* MCTP_ADDR_ANY for local owned tags */ 138 __u8 tag; /* incoming tag match; invert TO for local */ 139 140 /* we hold a ref to sk when set */ 141 struct sock *sk; 142 143 /* routing lookup list */ 144 struct hlist_node hlist; 145 146 /* per-socket list */ 147 struct hlist_node sklist; 148 149 /* lock protects against concurrent updates to the reassembly and 150 * expiry data below. 151 */ 152 spinlock_t lock; 153 154 /* Keys are referenced during the output path, which may sleep */ 155 refcount_t refs; 156 157 /* incoming fragment reassembly context */ 158 struct sk_buff *reasm_head; 159 struct sk_buff **reasm_tailp; 160 bool reasm_dead; 161 u8 last_seq; 162 163 /* key validity */ 164 bool valid; 165 166 /* expiry timeout; valid (above) cleared on expiry */ 167 unsigned long expiry; 168 169 /* free to use for device flow state tracking. Initialised to 170 * zero on initial key creation 171 */ 172 unsigned long dev_flow_state; 173 struct mctp_dev *dev; 174 175 /* a tag allocated with SIOCMCTPALLOCTAG ioctl will not expire 176 * automatically on timeout or response, instead SIOCMCTPDROPTAG 177 * is used. 178 */ 179 bool manual_alloc; 180 }; 181 182 struct mctp_skb_cb { 183 unsigned int magic; 184 unsigned int net; 185 int ifindex; /* extended/direct addressing if set */ 186 mctp_eid_t src; 187 unsigned char halen; 188 unsigned char haddr[MAX_ADDR_LEN]; 189 }; 190 191 /* skb control-block accessors with a little extra debugging for initial 192 * development. 193 * 194 * TODO: remove checks & mctp_skb_cb->magic; replace callers of __mctp_cb 195 * with mctp_cb(). 196 * 197 * __mctp_cb() is only for the initial ingress code; we should see ->magic set 198 * at all times after this. 199 */ __mctp_cb(struct sk_buff * skb)200 static inline struct mctp_skb_cb *__mctp_cb(struct sk_buff *skb) 201 { 202 struct mctp_skb_cb *cb = (void *)skb->cb; 203 204 cb->magic = 0x4d435450; 205 return cb; 206 } 207 mctp_cb(struct sk_buff * skb)208 static inline struct mctp_skb_cb *mctp_cb(struct sk_buff *skb) 209 { 210 struct mctp_skb_cb *cb = (void *)skb->cb; 211 212 BUILD_BUG_ON(sizeof(struct mctp_skb_cb) > sizeof(skb->cb)); 213 WARN_ON(cb->magic != 0x4d435450); 214 return (void *)(skb->cb); 215 } 216 217 /* If CONFIG_MCTP_FLOWS, we may add one of these as a SKB extension, 218 * indicating the flow to the device driver. 219 */ 220 struct mctp_flow { 221 struct mctp_sk_key *key; 222 }; 223 224 /* Route definition. 225 * 226 * These are held in the pernet->mctp.routes list, with RCU protection for 227 * removed routes. We hold a reference to the netdev; routes need to be 228 * dropped on NETDEV_UNREGISTER events. 229 * 230 * Updates to the route table are performed under rtnl; all reads under RCU, 231 * so routes cannot be referenced over a RCU grace period. Specifically: A 232 * caller cannot block between mctp_route_lookup and mctp_route_release() 233 */ 234 struct mctp_route { 235 mctp_eid_t min, max; 236 237 unsigned char type; 238 unsigned int mtu; 239 struct mctp_dev *dev; 240 int (*output)(struct mctp_route *route, 241 struct sk_buff *skb); 242 243 struct list_head list; 244 refcount_t refs; 245 struct rcu_head rcu; 246 }; 247 248 /* route interfaces */ 249 struct mctp_route *mctp_route_lookup(struct net *net, unsigned int dnet, 250 mctp_eid_t daddr); 251 252 /* always takes ownership of skb */ 253 int mctp_local_output(struct sock *sk, struct mctp_route *rt, 254 struct sk_buff *skb, mctp_eid_t daddr, u8 req_tag); 255 256 void mctp_key_unref(struct mctp_sk_key *key); 257 struct mctp_sk_key *mctp_alloc_local_tag(struct mctp_sock *msk, 258 mctp_eid_t daddr, mctp_eid_t saddr, 259 bool manual, u8 *tagp); 260 261 /* routing <--> device interface */ 262 unsigned int mctp_default_net(struct net *net); 263 int mctp_default_net_set(struct net *net, unsigned int index); 264 int mctp_route_add_local(struct mctp_dev *mdev, mctp_eid_t addr); 265 int mctp_route_remove_local(struct mctp_dev *mdev, mctp_eid_t addr); 266 void mctp_route_remove_dev(struct mctp_dev *mdev); 267 268 /* neighbour definitions */ 269 enum mctp_neigh_source { 270 MCTP_NEIGH_STATIC, 271 MCTP_NEIGH_DISCOVER, 272 }; 273 274 struct mctp_neigh { 275 struct mctp_dev *dev; 276 mctp_eid_t eid; 277 enum mctp_neigh_source source; 278 279 unsigned char ha[MAX_ADDR_LEN]; 280 281 struct list_head list; 282 struct rcu_head rcu; 283 }; 284 285 int mctp_neigh_init(void); 286 void mctp_neigh_exit(void); 287 288 // ret_hwaddr may be NULL, otherwise must have space for MAX_ADDR_LEN 289 int mctp_neigh_lookup(struct mctp_dev *dev, mctp_eid_t eid, 290 void *ret_hwaddr); 291 void mctp_neigh_remove_dev(struct mctp_dev *mdev); 292 293 int mctp_routes_init(void); 294 void mctp_routes_exit(void); 295 296 int mctp_device_init(void); 297 void mctp_device_exit(void); 298 299 #endif /* __NET_MCTP_H */ 300