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 67 /* Key for matching incoming packets to sockets or reassembly contexts. 68 * Packets are matched on (src,dest,tag). 69 * 70 * Lifetime requirements: 71 * 72 * - keys are free()ed via RCU 73 * 74 * - a mctp_sk_key contains a reference to a struct sock; this is valid 75 * for the life of the key. On sock destruction (through unhash), the key is 76 * removed from lists (see below), and will not be observable after a RCU 77 * grace period. 78 * 79 * any RX occurring within that grace period may still queue to the socket, 80 * but will hit the SOCK_DEAD case before the socket is freed. 81 * 82 * - these mctp_sk_keys appear on two lists: 83 * 1) the struct mctp_sock->keys list 84 * 2) the struct netns_mctp->keys list 85 * 86 * updates to either list are performed under the netns_mctp->keys 87 * lock. 88 * 89 * - a key may have a sk_buff attached as part of an in-progress message 90 * reassembly (->reasm_head). The reassembly context is protected by 91 * reasm_lock, which may be acquired with the keys lock (above) held, if 92 * necessary. Consequently, keys lock *cannot* be acquired with the 93 * reasm_lock held. 94 * 95 * - there are two destruction paths for a mctp_sk_key: 96 * 97 * - through socket unhash (see mctp_sk_unhash). This performs the list 98 * removal under keys_lock. 99 * 100 * - where a key is established to receive a reply message: after receiving 101 * the (complete) reply, or during reassembly errors. Here, we clean up 102 * the reassembly context (marking reasm_dead, to prevent another from 103 * starting), and remove the socket from the netns & socket lists. 104 */ 105 struct mctp_sk_key { 106 mctp_eid_t peer_addr; 107 mctp_eid_t local_addr; 108 __u8 tag; /* incoming tag match; invert TO for local */ 109 110 /* we hold a ref to sk when set */ 111 struct sock *sk; 112 113 /* routing lookup list */ 114 struct hlist_node hlist; 115 116 /* per-socket list */ 117 struct hlist_node sklist; 118 119 /* incoming fragment reassembly context */ 120 spinlock_t reasm_lock; 121 struct sk_buff *reasm_head; 122 struct sk_buff **reasm_tailp; 123 bool reasm_dead; 124 u8 last_seq; 125 126 struct rcu_head rcu; 127 }; 128 129 struct mctp_skb_cb { 130 unsigned int magic; 131 unsigned int net; 132 mctp_eid_t src; 133 }; 134 135 /* skb control-block accessors with a little extra debugging for initial 136 * development. 137 * 138 * TODO: remove checks & mctp_skb_cb->magic; replace callers of __mctp_cb 139 * with mctp_cb(). 140 * 141 * __mctp_cb() is only for the initial ingress code; we should see ->magic set 142 * at all times after this. 143 */ 144 static inline struct mctp_skb_cb *__mctp_cb(struct sk_buff *skb) 145 { 146 struct mctp_skb_cb *cb = (void *)skb->cb; 147 148 cb->magic = 0x4d435450; 149 return cb; 150 } 151 152 static inline struct mctp_skb_cb *mctp_cb(struct sk_buff *skb) 153 { 154 struct mctp_skb_cb *cb = (void *)skb->cb; 155 156 WARN_ON(cb->magic != 0x4d435450); 157 return (void *)(skb->cb); 158 } 159 160 /* Route definition. 161 * 162 * These are held in the pernet->mctp.routes list, with RCU protection for 163 * removed routes. We hold a reference to the netdev; routes need to be 164 * dropped on NETDEV_UNREGISTER events. 165 * 166 * Updates to the route table are performed under rtnl; all reads under RCU, 167 * so routes cannot be referenced over a RCU grace period. Specifically: A 168 * caller cannot block between mctp_route_lookup and passing the route to 169 * mctp_do_route. 170 */ 171 struct mctp_route { 172 mctp_eid_t min, max; 173 174 struct mctp_dev *dev; 175 unsigned int mtu; 176 unsigned char type; 177 int (*output)(struct mctp_route *route, 178 struct sk_buff *skb); 179 180 struct list_head list; 181 refcount_t refs; 182 struct rcu_head rcu; 183 }; 184 185 /* route interfaces */ 186 struct mctp_route *mctp_route_lookup(struct net *net, unsigned int dnet, 187 mctp_eid_t daddr); 188 189 int mctp_do_route(struct mctp_route *rt, struct sk_buff *skb); 190 191 int mctp_local_output(struct sock *sk, struct mctp_route *rt, 192 struct sk_buff *skb, mctp_eid_t daddr, u8 req_tag); 193 194 /* routing <--> device interface */ 195 unsigned int mctp_default_net(struct net *net); 196 int mctp_default_net_set(struct net *net, unsigned int index); 197 int mctp_route_add_local(struct mctp_dev *mdev, mctp_eid_t addr); 198 int mctp_route_remove_local(struct mctp_dev *mdev, mctp_eid_t addr); 199 void mctp_route_remove_dev(struct mctp_dev *mdev); 200 201 /* neighbour definitions */ 202 enum mctp_neigh_source { 203 MCTP_NEIGH_STATIC, 204 MCTP_NEIGH_DISCOVER, 205 }; 206 207 struct mctp_neigh { 208 struct mctp_dev *dev; 209 mctp_eid_t eid; 210 enum mctp_neigh_source source; 211 212 unsigned char ha[MAX_ADDR_LEN]; 213 214 struct list_head list; 215 struct rcu_head rcu; 216 }; 217 218 int mctp_neigh_init(void); 219 void mctp_neigh_exit(void); 220 221 // ret_hwaddr may be NULL, otherwise must have space for MAX_ADDR_LEN 222 int mctp_neigh_lookup(struct mctp_dev *dev, mctp_eid_t eid, 223 void *ret_hwaddr); 224 void mctp_neigh_remove_dev(struct mctp_dev *mdev); 225 226 int mctp_routes_init(void); 227 void mctp_routes_exit(void); 228 229 void mctp_device_init(void); 230 void mctp_device_exit(void); 231 232 #endif /* __NET_MCTP_H */ 233