/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * L2TP internal definitions.
+/* L2TP internal definitions.
*
* Copyright (c) 2008,2009 Katalix Systems Ltd
*/
#include <net/xfrm.h>
#endif
-/* Just some random numbers */
+/* Random numbers used for internal consistency checks of tunnel and session structures */
#define L2TP_TUNNEL_MAGIC 0x42114DDA
#define L2TP_SESSION_MAGIC 0x0C04EB7D
-/* Per tunnel, session hash table size */
+/* Per tunnel session hash table size */
#define L2TP_HASH_BITS 4
-#define L2TP_HASH_SIZE (1 << L2TP_HASH_BITS)
+#define L2TP_HASH_SIZE BIT(L2TP_HASH_BITS)
-/* System-wide, session hash table size */
+/* System-wide session hash table size */
#define L2TP_HASH_BITS_2 8
-#define L2TP_HASH_SIZE_2 (1 << L2TP_HASH_BITS_2)
+#define L2TP_HASH_SIZE_2 BIT(L2TP_HASH_BITS_2)
struct sk_buff;
struct l2tp_tunnel;
-/* Describes a session. Contains information to determine incoming
- * packets and transmit outgoing ones.
- */
+/* L2TP session configuration */
struct l2tp_session_cfg {
enum l2tp_pwtype pw_type;
- unsigned int recv_seq:1; /* expect receive packets with
- * sequence numbers? */
- unsigned int send_seq:1; /* send packets with sequence
- * numbers? */
- unsigned int lns_mode:1; /* behave as LNS? LAC enables
- * sequence numbers under
- * control of LNS. */
- int debug; /* bitmask of debug message
- * categories */
+ unsigned int recv_seq:1; /* expect receive packets with sequence numbers? */
+ unsigned int send_seq:1; /* send packets with sequence numbers? */
+ unsigned int lns_mode:1; /* behave as LNS?
+ * LAC enables sequence numbers under LNS control.
+ */
+ int debug; /* bitmask of debug message categories */
u16 l2specific_type; /* Layer 2 specific type */
u8 cookie[8]; /* optional cookie */
int cookie_len; /* 0, 4 or 8 bytes */
u8 peer_cookie[8]; /* peer's cookie */
int peer_cookie_len; /* 0, 4 or 8 bytes */
- int reorder_timeout; /* configured reorder timeout
- * (in jiffies) */
+ int reorder_timeout; /* configured reorder timeout (in jiffies) */
char *ifname;
};
+/* Represents a session (pseudowire) instance.
+ * Tracks runtime state including cookies, dataplane packet sequencing, and IO statistics.
+ * Is linked into a per-tunnel session hashlist; and in the case of an L2TPv3 session into
+ * an additional per-net ("global") hashlist.
+ */
struct l2tp_session {
- int magic; /* should be
- * L2TP_SESSION_MAGIC */
+ int magic; /* should be L2TP_SESSION_MAGIC */
long dead;
- struct l2tp_tunnel *tunnel; /* back pointer to tunnel
- * context */
+ struct l2tp_tunnel *tunnel; /* back pointer to tunnel context */
u32 session_id;
u32 peer_session_id;
u8 cookie[8];
u32 nr_max; /* max NR. Depends on tunnel */
u32 nr_window_size; /* NR window size */
u32 nr_oos; /* NR of last OOS packet */
- int nr_oos_count; /* For OOS recovery */
+ int nr_oos_count; /* for OOS recovery */
int nr_oos_count_max;
- struct hlist_node hlist; /* Hash list node */
+ struct hlist_node hlist; /* hash list node */
refcount_t ref_count;
char name[32]; /* for logging */
char ifname[IFNAMSIZ];
- unsigned int recv_seq:1; /* expect receive packets with
- * sequence numbers? */
- unsigned int send_seq:1; /* send packets with sequence
- * numbers? */
- unsigned int lns_mode:1; /* behave as LNS? LAC enables
- * sequence numbers under
- * control of LNS. */
- int debug; /* bitmask of debug message
- * categories */
- int reorder_timeout; /* configured reorder timeout
- * (in jiffies) */
+ unsigned int recv_seq:1; /* expect receive packets with sequence numbers? */
+ unsigned int send_seq:1; /* send packets with sequence numbers? */
+ unsigned int lns_mode:1; /* behave as LNS?
+ * LAC enables sequence numbers under LNS control.
+ */
+ int debug; /* bitmask of debug message categories */
+ int reorder_timeout; /* configured reorder timeout (in jiffies) */
int reorder_skip; /* set if skip to next nr */
enum l2tp_pwtype pwtype;
struct l2tp_stats stats;
- struct hlist_node global_hlist; /* Global hash list node */
+ struct hlist_node global_hlist; /* global hash list node */
- int (*build_header)(struct l2tp_session *session, void *buf);
+ /* Session receive handler for data packets.
+ * Each pseudowire implementation should implement this callback in order to
+ * handle incoming packets. Packets are passed to the pseudowire handler after
+ * reordering, if data sequence numbers are enabled for the session.
+ */
void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len);
+
+ /* Session close handler.
+ * Each pseudowire implementation may implement this callback in order to carry
+ * out pseudowire-specific shutdown actions.
+ * The callback is called by core after unhashing the session and purging its
+ * reorder queue.
+ */
void (*session_close)(struct l2tp_session *session);
+
+ /* Session show handler.
+ * Pseudowire-specific implementation of debugfs session rendering.
+ * The callback is called by l2tp_debugfs.c after rendering core session
+ * information.
+ */
void (*show)(struct seq_file *m, void *priv);
- u8 priv[]; /* private data */
+
+ u8 priv[]; /* private data */
};
-/* Describes the tunnel. It contains info to track all the associated
- * sessions so incoming packets can be sorted out
- */
+/* L2TP tunnel configuration */
struct l2tp_tunnel_cfg {
- int debug; /* bitmask of debug message
- * categories */
+ int debug; /* bitmask of debug message categories */
enum l2tp_encap_type encap;
/* Used only for kernel-created sockets */
udp6_zero_rx_checksums:1;
};
+/* Represents a tunnel instance.
+ * Tracks runtime state including IO statistics.
+ * Holds the tunnel socket (either passed from userspace or directly created by the kernel).
+ * Maintains a hashlist of sessions belonging to the tunnel instance.
+ * Is linked into a per-net list of tunnels.
+ */
struct l2tp_tunnel {
int magic; /* Should be L2TP_TUNNEL_MAGIC */
struct rcu_head rcu;
rwlock_t hlist_lock; /* protect session_hlist */
- bool acpt_newsess; /* Indicates whether this
- * tunnel accepts new sessions.
- * Protected by hlist_lock.
+ bool acpt_newsess; /* indicates whether this tunnel accepts
+ * new sessions. Protected by hlist_lock.
*/
struct hlist_head session_hlist[L2TP_HASH_SIZE];
- /* hashed list of sessions,
- * hashed by id */
+ /* hashed list of sessions, hashed by id */
u32 tunnel_id;
u32 peer_tunnel_id;
int version; /* 2=>L2TPv2, 3=>L2TPv3 */
char name[20]; /* for logging */
- int debug; /* bitmask of debug message
- * categories */
+ int debug; /* bitmask of debug message categories */
enum l2tp_encap_type encap;
struct l2tp_stats stats;
- struct list_head list; /* Keep a list of all tunnels */
+ struct list_head list; /* list node on per-namespace list of tunnels */
struct net *l2tp_net; /* the net we belong to */
refcount_t ref_count;
- void (*old_sk_destruct)(struct sock *);
- struct sock *sock; /* Parent socket */
- int fd; /* Parent fd, if tunnel socket
- * was created by userspace */
+ void (*old_sk_destruct)(struct sock *sk);
+ struct sock *sock; /* parent socket */
+ int fd; /* parent fd, if tunnel socket was created
+ * by userspace
+ */
struct work_struct del_work;
};
+/* Pseudowire ops callbacks for use with the l2tp genetlink interface */
struct l2tp_nl_cmd_ops {
+ /* The pseudowire session create callback is responsible for creating a session
+ * instance for a specific pseudowire type.
+ * It must call l2tp_session_create and l2tp_session_register to register the
+ * session instance, as well as carry out any pseudowire-specific initialisation.
+ * It must return >= 0 on success, or an appropriate negative errno value on failure.
+ */
int (*session_create)(struct net *net, struct l2tp_tunnel *tunnel,
u32 session_id, u32 peer_session_id,
struct l2tp_session_cfg *cfg);
- int (*session_delete)(struct l2tp_session *session);
+
+ /* The pseudowire session delete callback is responsible for initiating the deletion
+ * of a session instance.
+ * It must call l2tp_session_delete, as well as carry out any pseudowire-specific
+ * teardown actions.
+ */
+ void (*session_delete)(struct l2tp_session *session);
};
static inline void *l2tp_session_priv(struct l2tp_session *session)
return &session->priv[0];
}
+/* Tunnel and session refcounts */
+void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel);
+void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel);
+void l2tp_session_inc_refcount(struct l2tp_session *session);
+void l2tp_session_dec_refcount(struct l2tp_session *session);
+
+/* Tunnel and session lookup.
+ * These functions take a reference on the instances they return, so
+ * the caller must ensure that the reference is dropped appropriately.
+ */
struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id);
struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth);
struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel,
u32 session_id);
-void l2tp_tunnel_free(struct l2tp_tunnel *tunnel);
-
struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id);
struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth);
struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
const char *ifname);
+/* Tunnel and session lifetime management.
+ * Creation of a new instance is a two-step process: create, then register.
+ * Destruction is triggered using the *_delete functions, and completes asynchronously.
+ */
int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id,
u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg,
struct l2tp_tunnel **tunnelp);
int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net,
struct l2tp_tunnel_cfg *cfg);
-
void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel);
+
struct l2tp_session *l2tp_session_create(int priv_size,
struct l2tp_tunnel *tunnel,
u32 session_id, u32 peer_session_id,
struct l2tp_session_cfg *cfg);
int l2tp_session_register(struct l2tp_session *session,
struct l2tp_tunnel *tunnel);
+void l2tp_session_delete(struct l2tp_session *session);
-void __l2tp_session_unhash(struct l2tp_session *session);
-int l2tp_session_delete(struct l2tp_session *session);
-void l2tp_session_free(struct l2tp_session *session);
+/* Receive path helpers. If data sequencing is enabled for the session these
+ * functions handle queuing and reordering prior to passing packets to the
+ * pseudowire code to be passed to userspace.
+ */
void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
unsigned char *ptr, unsigned char *optr, u16 hdrflags,
int length);
int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);
-void l2tp_session_set_header_len(struct l2tp_session *session, int version);
+/* Transmit path helpers for sending packets over the tunnel socket. */
+void l2tp_session_set_header_len(struct l2tp_session *session, int version);
int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb,
int hdr_len);
-int l2tp_nl_register_ops(enum l2tp_pwtype pw_type,
- const struct l2tp_nl_cmd_ops *ops);
-void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
-int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg);
-
-static inline void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel)
-{
- refcount_inc(&tunnel->ref_count);
-}
-
-static inline void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel)
-{
- if (refcount_dec_and_test(&tunnel->ref_count))
- l2tp_tunnel_free(tunnel);
-}
-
-/* Session reference counts. Incremented when code obtains a reference
- * to a session.
+/* Pseudowire management.
+ * Pseudowires should register with l2tp core on module init, and unregister
+ * on module exit.
*/
-static inline void l2tp_session_inc_refcount(struct l2tp_session *session)
-{
- refcount_inc(&session->ref_count);
-}
+int l2tp_nl_register_ops(enum l2tp_pwtype pw_type, const struct l2tp_nl_cmd_ops *ops);
+void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
-static inline void l2tp_session_dec_refcount(struct l2tp_session *session)
-{
- if (refcount_dec_and_test(&session->ref_count))
- l2tp_session_free(session);
-}
+/* IOCTL helper for IP encap modules. */
+int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg);
static inline int l2tp_get_l2specific_len(struct l2tp_session *session)
{
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