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-rw-r--r--include/net/mctp.h298
1 files changed, 298 insertions, 0 deletions
diff --git a/include/net/mctp.h b/include/net/mctp.h
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--- /dev/null
+++ b/include/net/mctp.h
@@ -0,0 +1,298 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Management Component Transport Protocol (MCTP)
+ *
+ * Copyright (c) 2021 Code Construct
+ * Copyright (c) 2021 Google
+ */
+
+#ifndef __NET_MCTP_H
+#define __NET_MCTP_H
+
+#include <linux/bits.h>
+#include <linux/mctp.h>
+#include <linux/netdevice.h>
+#include <net/net_namespace.h>
+#include <net/sock.h>
+
+/* MCTP packet definitions */
+struct mctp_hdr {
+ u8 ver;
+ u8 dest;
+ u8 src;
+ u8 flags_seq_tag;
+};
+
+#define MCTP_VER_MIN 1
+#define MCTP_VER_MAX 1
+
+/* Definitions for flags_seq_tag field */
+#define MCTP_HDR_FLAG_SOM BIT(7)
+#define MCTP_HDR_FLAG_EOM BIT(6)
+#define MCTP_HDR_FLAG_TO BIT(3)
+#define MCTP_HDR_FLAGS GENMASK(5, 3)
+#define MCTP_HDR_SEQ_SHIFT 4
+#define MCTP_HDR_SEQ_MASK GENMASK(1, 0)
+#define MCTP_HDR_TAG_SHIFT 0
+#define MCTP_HDR_TAG_MASK GENMASK(2, 0)
+
+#define MCTP_INITIAL_DEFAULT_NET 1
+
+static inline bool mctp_address_unicast(mctp_eid_t eid)
+{
+ return eid >= 8 && eid < 255;
+}
+
+static inline bool mctp_address_broadcast(mctp_eid_t eid)
+{
+ return eid == 255;
+}
+
+static inline bool mctp_address_null(mctp_eid_t eid)
+{
+ return eid == 0;
+}
+
+static inline bool mctp_address_matches(mctp_eid_t match, mctp_eid_t eid)
+{
+ return match == eid || match == MCTP_ADDR_ANY;
+}
+
+static inline struct mctp_hdr *mctp_hdr(struct sk_buff *skb)
+{
+ return (struct mctp_hdr *)skb_network_header(skb);
+}
+
+/* socket implementation */
+struct mctp_sock {
+ struct sock sk;
+
+ /* bind() params */
+ unsigned int bind_net;
+ mctp_eid_t bind_addr;
+ __u8 bind_type;
+
+ /* sendmsg()/recvmsg() uses struct sockaddr_mctp_ext */
+ bool addr_ext;
+
+ /* list of mctp_sk_key, for incoming tag lookup. updates protected
+ * by sk->net->keys_lock
+ */
+ struct hlist_head keys;
+
+ /* mechanism for expiring allocated keys; will release an allocated
+ * tag, and any netdev state for a request/response pairing
+ */
+ struct timer_list key_expiry;
+};
+
+/* Key for matching incoming packets to sockets or reassembly contexts.
+ * Packets are matched on (src,dest,tag).
+ *
+ * Lifetime / locking requirements:
+ *
+ * - individual key data (ie, the struct itself) is protected by key->lock;
+ * changes must be made with that lock held.
+ *
+ * - the lookup fields: peer_addr, local_addr and tag are set before the
+ * key is added to lookup lists, and never updated.
+ *
+ * - A ref to the key must be held (throuh key->refs) if a pointer to the
+ * key is to be accessed after key->lock is released.
+ *
+ * - a mctp_sk_key contains a reference to a struct sock; this is valid
+ * for the life of the key. On sock destruction (through unhash), the key is
+ * removed from lists (see below), and marked invalid.
+ *
+ * - these mctp_sk_keys appear on two lists:
+ * 1) the struct mctp_sock->keys list
+ * 2) the struct netns_mctp->keys list
+ *
+ * presences on these lists requires a (single) refcount to be held; both
+ * lists are updated as a single operation.
+ *
+ * Updates and lookups in either list are performed under the
+ * netns_mctp->keys lock. Lookup functions will need to lock the key and
+ * take a reference before unlocking the keys_lock. Consequently, the list's
+ * keys_lock *cannot* be acquired with the individual key->lock held.
+ *
+ * - a key may have a sk_buff attached as part of an in-progress message
+ * reassembly (->reasm_head). The reasm data is protected by the individual
+ * key->lock.
+ *
+ * - there are two destruction paths for a mctp_sk_key:
+ *
+ * - through socket unhash (see mctp_sk_unhash). This performs the list
+ * removal under keys_lock.
+ *
+ * - where a key is established to receive a reply message: after receiving
+ * the (complete) reply, or during reassembly errors. Here, we clean up
+ * the reassembly context (marking reasm_dead, to prevent another from
+ * starting), and remove the socket from the netns & socket lists.
+ *
+ * - through an expiry timeout, on a per-socket timer
+ */
+struct mctp_sk_key {
+ mctp_eid_t peer_addr;
+ mctp_eid_t local_addr; /* MCTP_ADDR_ANY for local owned tags */
+ __u8 tag; /* incoming tag match; invert TO for local */
+
+ /* we hold a ref to sk when set */
+ struct sock *sk;
+
+ /* routing lookup list */
+ struct hlist_node hlist;
+
+ /* per-socket list */
+ struct hlist_node sklist;
+
+ /* lock protects against concurrent updates to the reassembly and
+ * expiry data below.
+ */
+ spinlock_t lock;
+
+ /* Keys are referenced during the output path, which may sleep */
+ refcount_t refs;
+
+ /* incoming fragment reassembly context */
+ struct sk_buff *reasm_head;
+ struct sk_buff **reasm_tailp;
+ bool reasm_dead;
+ u8 last_seq;
+
+ /* key validity */
+ bool valid;
+
+ /* expiry timeout; valid (above) cleared on expiry */
+ unsigned long expiry;
+
+ /* free to use for device flow state tracking. Initialised to
+ * zero on initial key creation
+ */
+ unsigned long dev_flow_state;
+ struct mctp_dev *dev;
+
+ /* a tag allocated with SIOCMCTPALLOCTAG ioctl will not expire
+ * automatically on timeout or response, instead SIOCMCTPDROPTAG
+ * is used.
+ */
+ bool manual_alloc;
+};
+
+struct mctp_skb_cb {
+ unsigned int magic;
+ unsigned int net;
+ int ifindex; /* extended/direct addressing if set */
+ mctp_eid_t src;
+ unsigned char halen;
+ unsigned char haddr[MAX_ADDR_LEN];
+};
+
+/* skb control-block accessors with a little extra debugging for initial
+ * development.
+ *
+ * TODO: remove checks & mctp_skb_cb->magic; replace callers of __mctp_cb
+ * with mctp_cb().
+ *
+ * __mctp_cb() is only for the initial ingress code; we should see ->magic set
+ * at all times after this.
+ */
+static inline struct mctp_skb_cb *__mctp_cb(struct sk_buff *skb)
+{
+ struct mctp_skb_cb *cb = (void *)skb->cb;
+
+ cb->magic = 0x4d435450;
+ return cb;
+}
+
+static inline struct mctp_skb_cb *mctp_cb(struct sk_buff *skb)
+{
+ struct mctp_skb_cb *cb = (void *)skb->cb;
+
+ BUILD_BUG_ON(sizeof(struct mctp_skb_cb) > sizeof(skb->cb));
+ WARN_ON(cb->magic != 0x4d435450);
+ return (void *)(skb->cb);
+}
+
+/* If CONFIG_MCTP_FLOWS, we may add one of these as a SKB extension,
+ * indicating the flow to the device driver.
+ */
+struct mctp_flow {
+ struct mctp_sk_key *key;
+};
+
+/* Route definition.
+ *
+ * These are held in the pernet->mctp.routes list, with RCU protection for
+ * removed routes. We hold a reference to the netdev; routes need to be
+ * dropped on NETDEV_UNREGISTER events.
+ *
+ * Updates to the route table are performed under rtnl; all reads under RCU,
+ * so routes cannot be referenced over a RCU grace period. Specifically: A
+ * caller cannot block between mctp_route_lookup and mctp_route_release()
+ */
+struct mctp_route {
+ mctp_eid_t min, max;
+
+ struct mctp_dev *dev;
+ unsigned int mtu;
+ unsigned char type;
+ int (*output)(struct mctp_route *route,
+ struct sk_buff *skb);
+
+ struct list_head list;
+ refcount_t refs;
+ struct rcu_head rcu;
+};
+
+/* route interfaces */
+struct mctp_route *mctp_route_lookup(struct net *net, unsigned int dnet,
+ mctp_eid_t daddr);
+
+int mctp_local_output(struct sock *sk, struct mctp_route *rt,
+ struct sk_buff *skb, mctp_eid_t daddr, u8 req_tag);
+
+void mctp_key_unref(struct mctp_sk_key *key);
+struct mctp_sk_key *mctp_alloc_local_tag(struct mctp_sock *msk,
+ mctp_eid_t daddr, mctp_eid_t saddr,
+ bool manual, u8 *tagp);
+
+/* routing <--> device interface */
+unsigned int mctp_default_net(struct net *net);
+int mctp_default_net_set(struct net *net, unsigned int index);
+int mctp_route_add_local(struct mctp_dev *mdev, mctp_eid_t addr);
+int mctp_route_remove_local(struct mctp_dev *mdev, mctp_eid_t addr);
+void mctp_route_remove_dev(struct mctp_dev *mdev);
+
+/* neighbour definitions */
+enum mctp_neigh_source {
+ MCTP_NEIGH_STATIC,
+ MCTP_NEIGH_DISCOVER,
+};
+
+struct mctp_neigh {
+ struct mctp_dev *dev;
+ mctp_eid_t eid;
+ enum mctp_neigh_source source;
+
+ unsigned char ha[MAX_ADDR_LEN];
+
+ struct list_head list;
+ struct rcu_head rcu;
+};
+
+int mctp_neigh_init(void);
+void mctp_neigh_exit(void);
+
+// ret_hwaddr may be NULL, otherwise must have space for MAX_ADDR_LEN
+int mctp_neigh_lookup(struct mctp_dev *dev, mctp_eid_t eid,
+ void *ret_hwaddr);
+void mctp_neigh_remove_dev(struct mctp_dev *mdev);
+
+int mctp_routes_init(void);
+void mctp_routes_exit(void);
+
+void mctp_device_init(void);
+void mctp_device_exit(void);
+
+#endif /* __NET_MCTP_H */