xfrm.h

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#ifndef _NET_XFRM_H
#define _NET_XFRM_H

#include <linux/compiler.h>
#include <linux/xfrm.h>
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/skbuff.h>
#include <linux/socket.h>
#include <linux/pfkeyv2.h>
#include <linux/ipsec.h>
#include <linux/in6.h>
#include <linux/mutex.h>
#include <linux/audit.h>

#include <net/sock.h>
#include <net/dst.h>
#include <net/ip.h>
#include <net/route.h>
#include <net/ipv6.h>
#include <net/ip6_fib.h>

#define XFRM_PROTO_ESP		50
#define XFRM_PROTO_AH		51
#define XFRM_PROTO_COMP		108
#define XFRM_PROTO_IPIP		4
#define XFRM_PROTO_IPV6		41
#define XFRM_PROTO_ROUTING	IPPROTO_ROUTING
#define XFRM_PROTO_DSTOPTS	IPPROTO_DSTOPTS

#define XFRM_ALIGN8(len)	(((len) + 7) & ~7)
#define MODULE_ALIAS_XFRM_MODE(family, encap) \
	MODULE_ALIAS("xfrm-mode-" __stringify(family) "-" __stringify(encap))
#define MODULE_ALIAS_XFRM_TYPE(family, proto) \
	MODULE_ALIAS("xfrm-type-" __stringify(family) "-" __stringify(proto))

extern struct sock *xfrm_nl;
extern u32 sysctl_xfrm_aevent_etime;
extern u32 sysctl_xfrm_aevent_rseqth;
extern int sysctl_xfrm_larval_drop;
extern u32 sysctl_xfrm_acq_expires;

extern struct mutex xfrm_cfg_mutex;

/* Organization of SPD aka "XFRM rules"
   ------------------------------------

   Basic objects:
   - policy rule, struct xfrm_policy (=SPD entry)
   - bundle of transformations, struct dst_entry == struct xfrm_dst (=SA bundle)
   - instance of a transformer, struct xfrm_state (=SA)
   - template to clone xfrm_state, struct xfrm_tmpl

   SPD is plain linear list of xfrm_policy rules, ordered by priority.
   (To be compatible with existing pfkeyv2 implementations,
   many rules with priority of 0x7fffffff are allowed to exist and
   such rules are ordered in an unpredictable way, thanks to bsd folks.)

   Lookup is plain linear search until the first match with selector.

   If "action" is "block", then we prohibit the flow, otherwise:
   if "xfrms_nr" is zero, the flow passes untransformed. Otherwise,
   policy entry has list of up to XFRM_MAX_DEPTH transformations,
   described by templates xfrm_tmpl. Each template is resolved
   to a complete xfrm_state (see below) and we pack bundle of transformations
   to a dst_entry returned to requestor.

   dst -. xfrm  .-> xfrm_state #1
    |---. child .-> dst -. xfrm .-> xfrm_state #2
                     |---. child .-> dst -. xfrm .-> xfrm_state #3
                                      |---. child .-> NULL

   Bundles are cached at xrfm_policy struct (field ->bundles).


   Resolution of xrfm_tmpl
   -----------------------
   Template contains:
   1. ->mode		Mode: transport or tunnel
   2. ->id.proto	Protocol: AH/ESP/IPCOMP
   3. ->id.daddr	Remote tunnel endpoint, ignored for transport mode.
      Q: allow to resolve security gateway?
   4. ->id.spi          If not zero, static SPI.
   5. ->saddr		Local tunnel endpoint, ignored for transport mode.
   6. ->algos		List of allowed algos. Plain bitmask now.
      Q: ealgos, aalgos, calgos. What a mess...
   7. ->share		Sharing mode.
      Q: how to implement private sharing mode? To add struct sock* to
      flow id?

   Having this template we search through SAD searching for entries
   with appropriate mode/proto/algo, permitted by selector.
   If no appropriate entry found, it is requested from key manager.

   PROBLEMS:
   Q: How to find all the bundles referring to a physical path for
      PMTU discovery? Seems, dst should contain list of all parents...
      and enter to infinite locking hierarchy disaster.
      No! It is easier, we will not search for them, let them find us.
      We add genid to each dst plus pointer to genid of raw IP route,
      pmtu disc will update pmtu on raw IP route and increase its genid.
      dst_check() will see this for top level and trigger resyncing
      metrics. Plus, it will be made via sk->sk_dst_cache. Solved.
 */

/* Full description of state of transformer. */
struct xfrm_state
{
	/* Note: bydst is re-used during gc */
	struct hlist_node	bydst;
	struct hlist_node	bysrc;
	struct hlist_node	byspi;

	atomic_t		refcnt;
	spinlock_t		lock;

	struct xfrm_id		id;
	struct xfrm_selector	sel;

	u32			genid;

	/* Key manger bits */
	struct {
		u8		state;
		u8		dying;
		u32		seq;
	} km;

	/* Parameters of this state. */
	struct {
		u32		reqid;
		u8		mode;
		u8		replay_window;
		u8		aalgo, ealgo, calgo;
		u8		flags;
		u16		family;
		xfrm_address_t	saddr;
		int		header_len;
		int		trailer_len;
	} props;

	struct xfrm_lifetime_cfg lft;

	/* Data for transformer */
	struct xfrm_algo	*aalg;
	struct xfrm_algo	*ealg;
	struct xfrm_algo	*calg;

	/* Data for encapsulator */
	struct xfrm_encap_tmpl	*encap;

	/* Data for care-of address */
	xfrm_address_t	*coaddr;

	/* IPComp needs an IPIP tunnel for handling uncompressed packets */
	struct xfrm_state	*tunnel;

	/* If a tunnel, number of users + 1 */
	atomic_t		tunnel_users;

	/* State for replay detection */
	struct xfrm_replay_state replay;

	/* Replay detection state at the time we sent the last notification */
	struct xfrm_replay_state preplay;

	/* internal flag that only holds state for delayed aevent at the
	 * moment
	*/
	u32			xflags;

	/* Replay detection notification settings */
	u32			replay_maxage;
	u32			replay_maxdiff;

	/* Replay detection notification timer */
	struct timer_list	rtimer;

	/* Statistics */
	struct xfrm_stats	stats;

	struct xfrm_lifetime_cur curlft;
	struct timer_list	timer;

	/* Last used time */
	u64			lastused;

	/* Reference to data common to all the instances of this
	 * transformer. */
	struct xfrm_type	*type;
	struct xfrm_mode	*inner_mode;
	struct xfrm_mode	*outer_mode;

	/* Security context */
	struct xfrm_sec_ctx	*security;

	/* Private data of this transformer, format is opaque,
	 * interpreted by xfrm_type methods. */
	void			*data;
};

/* xflags - make enum if more show up */
#define XFRM_TIME_DEFER	1

enum {
	XFRM_STATE_VOID,
	XFRM_STATE_ACQ,
	XFRM_STATE_VALID,
	XFRM_STATE_ERROR,
	XFRM_STATE_EXPIRED,
	XFRM_STATE_DEAD
};

/* callback structure passed from either netlink or pfkey */
struct km_event
{
	union {
		u32 hard;
		u32 proto;
		u32 byid;
		u32 aevent;
		u32 type;
	} data;

	u32	seq;
	u32	pid;
	u32	event;
};

struct xfrm_type;
struct xfrm_dst;
struct xfrm_policy_afinfo {
	unsigned short		family;
	struct dst_ops		*dst_ops;
	void			(*garbage_collect)(void);
	int			(*dst_lookup)(struct xfrm_dst **dst, struct flowi *fl);
	int			(*get_saddr)(xfrm_address_t *saddr, xfrm_address_t *daddr);
	struct dst_entry	*(*find_bundle)(struct flowi *fl, struct xfrm_policy *policy);
	int			(*bundle_create)(struct xfrm_policy *policy, 
						 struct xfrm_state **xfrm, 
						 int nx,
						 struct flowi *fl, 
						 struct dst_entry **dst_p);
	void			(*decode_session)(struct sk_buff *skb,
						  struct flowi *fl);
};

extern int xfrm_policy_register_afinfo(struct xfrm_policy_afinfo *afinfo);
extern int xfrm_policy_unregister_afinfo(struct xfrm_policy_afinfo *afinfo);
extern void km_policy_notify(struct xfrm_policy *xp, int dir, struct km_event *c);
extern void km_state_notify(struct xfrm_state *x, struct km_event *c);

struct xfrm_tmpl;
extern int km_query(struct xfrm_state *x, struct xfrm_tmpl *t, struct xfrm_policy *pol);
extern void km_state_expired(struct xfrm_state *x, int hard, u32 pid);
extern int __xfrm_state_delete(struct xfrm_state *x);

struct xfrm_state_afinfo {
	unsigned int		family;
	struct module		*owner;
	struct xfrm_type	*type_map[IPPROTO_MAX];
	struct xfrm_mode	*mode_map[XFRM_MODE_MAX];
	int			(*init_flags)(struct xfrm_state *x);
	void			(*init_tempsel)(struct xfrm_state *x, struct flowi *fl,
						struct xfrm_tmpl *tmpl,
						xfrm_address_t *daddr, xfrm_address_t *saddr);
	int			(*tmpl_sort)(struct xfrm_tmpl **dst, struct xfrm_tmpl **src, int n);
	int			(*state_sort)(struct xfrm_state **dst, struct xfrm_state **src, int n);
	int			(*output)(struct sk_buff *skb);
};

extern int xfrm_state_register_afinfo(struct xfrm_state_afinfo *afinfo);
extern int xfrm_state_unregister_afinfo(struct xfrm_state_afinfo *afinfo);

extern void xfrm_state_delete_tunnel(struct xfrm_state *x);

struct xfrm_type
{
	char			*description;
	struct module		*owner;
	__u8			proto;
	__u8			flags;
#define XFRM_TYPE_NON_FRAGMENT	1
#define XFRM_TYPE_REPLAY_PROT	2

	int			(*init_state)(struct xfrm_state *x);
	void			(*destructor)(struct xfrm_state *);
	int			(*input)(struct xfrm_state *, struct sk_buff *skb);
	int			(*output)(struct xfrm_state *, struct sk_buff *pskb);
	int			(*reject)(struct xfrm_state *, struct sk_buff *, struct flowi *);
	int			(*hdr_offset)(struct xfrm_state *, struct sk_buff *, u8 **);
	xfrm_address_t		*(*local_addr)(struct xfrm_state *, xfrm_address_t *);
	xfrm_address_t		*(*remote_addr)(struct xfrm_state *, xfrm_address_t *);
	/* Estimate maximal size of result of transformation of a dgram */
	u32			(*get_mtu)(struct xfrm_state *, int size);
};

extern int xfrm_register_type(struct xfrm_type *type, unsigned short family);
extern int xfrm_unregister_type(struct xfrm_type *type, unsigned short family);

struct xfrm_mode {
	int (*input)(struct xfrm_state *x, struct sk_buff *skb);

	/*
	 * Add encapsulation header.
	 *
	 * On exit, the transport header will be set to the start of the
	 * encapsulation header to be filled in by x->type->output and
	 * the mac header will be set to the nextheader (protocol for
	 * IPv4) field of the extension header directly preceding the
	 * encapsulation header, or in its absence, that of the top IP
	 * header.  The value of the network header will always point
	 * to the top IP header while skb->data will point to the payload.
	 */
	int (*output)(struct xfrm_state *x,struct sk_buff *skb);

	struct xfrm_state_afinfo *afinfo;
	struct module *owner;
	unsigned int encap;
	int flags;
};

/* Flags for xfrm_mode. */
enum {
	XFRM_MODE_FLAG_TUNNEL = 1,
};

extern int xfrm_register_mode(struct xfrm_mode *mode, int family);
extern int xfrm_unregister_mode(struct xfrm_mode *mode, int family);

struct xfrm_tmpl
{
/* id in template is interpreted as:
 * daddr - destination of tunnel, may be zero for transport mode.
 * spi   - zero to acquire spi. Not zero if spi is static, then
 *	   daddr must be fixed too.
 * proto - AH/ESP/IPCOMP
 */
	struct xfrm_id		id;

/* Source address of tunnel. Ignored, if it is not a tunnel. */
	xfrm_address_t		saddr;

	unsigned short		encap_family;

	__u32			reqid;

/* Mode: transport, tunnel etc. */
	__u8			mode;

/* Sharing mode: unique, this session only, this user only etc. */
	__u8			share;

/* May skip this transfomration if no SA is found */
	__u8			optional;

/* Bit mask of algos allowed for acquisition */
	__u32			aalgos;
	__u32			ealgos;
	__u32			calgos;
};

#define XFRM_MAX_DEPTH		6

struct xfrm_policy
{
	struct xfrm_policy	*next;
	struct hlist_node	bydst;
	struct hlist_node	byidx;

	/* This lock only affects elements except for entry. */
	rwlock_t		lock;
	atomic_t		refcnt;
	struct timer_list	timer;

	u32			priority;
	u32			index;
	struct xfrm_selector	selector;
	struct xfrm_lifetime_cfg lft;
	struct xfrm_lifetime_cur curlft;
	struct dst_entry       *bundles;
	u16			family;
	u8			type;
	u8			action;
	u8			flags;
	u8			dead;
	u8			xfrm_nr;
	/* XXX 1 byte hole, try to pack */
	struct xfrm_sec_ctx	*security;
	struct xfrm_tmpl       	xfrm_vec[XFRM_MAX_DEPTH];
};

struct xfrm_migrate {
	xfrm_address_t		old_daddr;
	xfrm_address_t		old_saddr;
	xfrm_address_t		new_daddr;
	xfrm_address_t		new_saddr;
	u8			proto;
	u8			mode;
	u16			reserved;
	u32			reqid;
	u16			old_family;
	u16			new_family;
};

#define XFRM_KM_TIMEOUT                30