include/net/mctp.h - linux - Git at Google

 /* 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_HEADER_MAXLEN	4

 #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 */
	/* 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_HEADER_MAXLEN 4

	#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 */