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 */ 19struct 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 41static inline bool mctp_address_unicast(mctp_eid_t eid) 42{ 43 return eid >= 8 && eid < 255; 44} 45 46static inline bool mctp_address_broadcast(mctp_eid_t eid) 47{ 48 return eid == 255; 49} 50 51static inline bool mctp_address_null(mctp_eid_t eid) 52{ 53 return eid == 0; 54} 55 56static inline bool mctp_address_matches(mctp_eid_t match, mctp_eid_t eid) 57{ 58 return match == eid || match == MCTP_ADDR_ANY; 59} 60 61static 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 */ 67struct 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 (peer EID, local EID, 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 */ 135struct mctp_sk_key { 136 unsigned int net; 137 mctp_eid_t peer_addr; 138 mctp_eid_t local_addr; /* MCTP_ADDR_ANY for local owned tags */ 139 __u8 tag; /* incoming tag match; invert TO for local */ 140 141 /* we hold a ref to sk when set */ 142 struct sock *sk; 143 144 /* routing lookup list */ 145 struct hlist_node hlist; 146 147 /* per-socket list */ 148 struct hlist_node sklist; 149 150 /* lock protects against concurrent updates to the reassembly and 151 * expiry data below. 152 */ 153 spinlock_t lock; 154 155 /* Keys are referenced during the output path, which may sleep */ 156 refcount_t refs; 157 158 /* incoming fragment reassembly context */ 159 struct sk_buff *reasm_head; 160 struct sk_buff **reasm_tailp; 161 bool reasm_dead; 162 u8 last_seq; 163 164 /* key validity */ 165 bool valid; 166 167 /* expiry timeout; valid (above) cleared on expiry */ 168 unsigned long expiry; 169 170 /* free to use for device flow state tracking. Initialised to 171 * zero on initial key creation 172 */ 173 unsigned long dev_flow_state; 174 struct mctp_dev *dev; 175 176 /* a tag allocated with SIOCMCTPALLOCTAG ioctl will not expire 177 * automatically on timeout or response, instead SIOCMCTPDROPTAG 178 * is used. 179 */ 180 bool manual_alloc; 181}; 182 183struct mctp_skb_cb { 184 unsigned int magic; 185 unsigned int net; 186 int ifindex; /* extended/direct addressing if set */ 187 mctp_eid_t src; 188 unsigned char halen; 189 unsigned char haddr[MAX_ADDR_LEN]; 190}; 191 192/* skb control-block accessors with a little extra debugging for initial 193 * development. 194 * 195 * TODO: remove checks & mctp_skb_cb->magic; replace callers of __mctp_cb 196 * with mctp_cb(). 197 * 198 * __mctp_cb() is only for the initial ingress code; we should see ->magic set 199 * at all times after this. 200 */ 201static inline struct mctp_skb_cb *__mctp_cb(struct sk_buff *skb) 202{ 203 struct mctp_skb_cb *cb = (void *)skb->cb; 204 205 cb->magic = 0x4d435450; 206 return cb; 207} 208 209static inline struct mctp_skb_cb *mctp_cb(struct sk_buff *skb) 210{ 211 struct mctp_skb_cb *cb = (void *)skb->cb; 212 213 BUILD_BUG_ON(sizeof(struct mctp_skb_cb) > sizeof(skb->cb)); 214 WARN_ON(cb->magic != 0x4d435450); 215 return (void *)(skb->cb); 216} 217 218/* If CONFIG_MCTP_FLOWS, we may add one of these as a SKB extension, 219 * indicating the flow to the device driver. 220 */ 221struct mctp_flow { 222 struct mctp_sk_key *key; 223}; 224 225/* Route definition. 226 * 227 * These are held in the pernet->mctp.routes list, with RCU protection for 228 * removed routes. We hold a reference to the netdev; routes need to be 229 * dropped on NETDEV_UNREGISTER events. 230 * 231 * Updates to the route table are performed under rtnl; all reads under RCU, 232 * so routes cannot be referenced over a RCU grace period. Specifically: A 233 * caller cannot block between mctp_route_lookup and mctp_route_release() 234 */ 235struct mctp_route { 236 mctp_eid_t min, max; 237 238 unsigned char type; 239 unsigned int mtu; 240 struct mctp_dev *dev; 241 int (*output)(struct mctp_route *route, 242 struct sk_buff *skb); 243 244 struct list_head list; 245 refcount_t refs; 246 struct rcu_head rcu; 247}; 248 249/* route interfaces */ 250struct mctp_route *mctp_route_lookup(struct net *net, unsigned int dnet, 251 mctp_eid_t daddr); 252 253/* always takes ownership of skb */ 254int mctp_local_output(struct sock *sk, struct mctp_route *rt, 255 struct sk_buff *skb, mctp_eid_t daddr, u8 req_tag); 256 257void mctp_key_unref(struct mctp_sk_key *key); 258struct mctp_sk_key *mctp_alloc_local_tag(struct mctp_sock *msk, 259 unsigned int netid, 260 mctp_eid_t local, mctp_eid_t peer, 261 bool manual, u8 *tagp); 262 263/* routing <--> device interface */ 264unsigned int mctp_default_net(struct net *net); 265int mctp_default_net_set(struct net *net, unsigned int index); 266int mctp_route_add_local(struct mctp_dev *mdev, mctp_eid_t addr); 267int mctp_route_remove_local(struct mctp_dev *mdev, mctp_eid_t addr); 268void mctp_route_remove_dev(struct mctp_dev *mdev); 269 270/* neighbour definitions */ 271enum mctp_neigh_source { 272 MCTP_NEIGH_STATIC, 273 MCTP_NEIGH_DISCOVER, 274}; 275 276struct mctp_neigh { 277 struct mctp_dev *dev; 278 mctp_eid_t eid; 279 enum mctp_neigh_source source; 280 281 unsigned char ha[MAX_ADDR_LEN]; 282 283 struct list_head list; 284 struct rcu_head rcu; 285}; 286 287int mctp_neigh_init(void); 288void mctp_neigh_exit(void); 289 290// ret_hwaddr may be NULL, otherwise must have space for MAX_ADDR_LEN 291int mctp_neigh_lookup(struct mctp_dev *dev, mctp_eid_t eid, 292 void *ret_hwaddr); 293void mctp_neigh_remove_dev(struct mctp_dev *mdev); 294 295int mctp_routes_init(void); 296void mctp_routes_exit(void); 297 298void mctp_device_init(void); 299void mctp_device_exit(void); 300 301#endif /* __NET_MCTP_H */ 302