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54652eb12c
linux/net/l2tp/l2tp_core.h
Guillaume Nault 54652eb12c l2tp: hold tunnel while looking up sessions in l2tp_netlink 
l2tp_tunnel_find() doesn't take a reference on the returned tunnel.
Therefore, it's unsafe to use it because the returned tunnel can go
away on us anytime.

Fix this by defining l2tp_tunnel_get(), which works like
l2tp_tunnel_find(), but takes a reference on the returned tunnel.
Caller then has to drop this reference using l2tp_tunnel_dec_refcount().

As l2tp_tunnel_dec_refcount() needs to be moved to l2tp_core.h, let's
simplify the patch and not move the L2TP_REFCNT_DEBUG part. This code
has been broken (not even compiling) in May 2012 by
commit a4ca44fa57 ("net: l2tp: Standardize logging styles")
and fixed more than two years later by
commit 29abe2fda5 ("l2tp: fix missing line continuation"). So it
doesn't appear to be used by anyone.

Same thing for l2tp_tunnel_free(); instead of moving it to l2tp_core.h,
let's just simplify things and call kfree_rcu() directly in
l2tp_tunnel_dec_refcount(). Extra assertions and debugging code
provided by l2tp_tunnel_free() didn't help catching any of the
reference counting and socket handling issues found while working on
this series.

Fixes: 309795f4be ("l2tp: Add netlink control API for L2TP")
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-08-28 11:34:58 -07:00

336 lines
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/*
* L2TP internal definitions.
*
* Copyright (c) 2008,2009 Katalix Systems Ltd
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/refcount.h>
#ifndef _L2TP_CORE_H_
#define _L2TP_CORE_H_
/* Just some random numbers */
#define L2TP_TUNNEL_MAGIC 0x42114DDA
#define L2TP_SESSION_MAGIC 0x0C04EB7D
/* Per tunnel, session hash table size */
#define L2TP_HASH_BITS 4
#define L2TP_HASH_SIZE (1 << L2TP_HASH_BITS)
/* System-wide, session hash table size */
#define L2TP_HASH_BITS_2 8
#define L2TP_HASH_SIZE_2 (1 << L2TP_HASH_BITS_2)
struct sk_buff;
struct l2tp_stats {
atomic_long_t tx_packets;
atomic_long_t tx_bytes;
atomic_long_t tx_errors;
atomic_long_t rx_packets;
atomic_long_t rx_bytes;
atomic_long_t rx_seq_discards;
atomic_long_t rx_oos_packets;
atomic_long_t rx_errors;
atomic_long_t rx_cookie_discards;
};
struct l2tp_tunnel;
/* Describes a session. Contains information to determine incoming
* packets and transmit outgoing ones.
*/
struct l2tp_session_cfg {
enum l2tp_pwtype pw_type;
unsigned int data_seq:2; /* data sequencing level
* 0 => none, 1 => IP only,
* 2 => all
*/
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 */
u16 vlan_id; /* VLAN pseudowire only */
u16 offset; /* offset to payload */
u16 l2specific_len; /* Layer 2 specific length */
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 mtu;
int mru;
char *ifname;
};
struct l2tp_session {
int magic; /* should be
* L2TP_SESSION_MAGIC */
struct l2tp_tunnel *tunnel; /* back pointer to tunnel
* context */
u32 session_id;
u32 peer_session_id;
u8 cookie[8];
int cookie_len;
u8 peer_cookie[8];
int peer_cookie_len;
u16 offset; /* offset from end of L2TP header
to beginning of data */
u16 l2specific_len;
u16 l2specific_type;
u16 hdr_len;
u32 nr; /* session NR state (receive) */
u32 ns; /* session NR state (send) */
struct sk_buff_head reorder_q; /* receive reorder queue */
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_max;
struct hlist_node hlist; /* Hash list node */
refcount_t ref_count;
char name[32]; /* for logging */
char ifname[IFNAMSIZ];
unsigned int data_seq:2; /* data sequencing level
* 0 => none, 1 => IP only,
* 2 => all
*/
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) */
int reorder_skip; /* set if skip to next nr */
int mtu;
int mru;
enum l2tp_pwtype pwtype;
struct l2tp_stats stats;
struct hlist_node global_hlist; /* Global hash list node */
int (*build_header)(struct l2tp_session *session, void *buf);
void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len);
void (*session_close)(struct l2tp_session *session);
void (*ref)(struct l2tp_session *session);
void (*deref)(struct l2tp_session *session);
#if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
void (*show)(struct seq_file *m, void *priv);
#endif
uint8_t priv[0]; /* private data */
};
/* Describes the tunnel. It contains info to track all the associated
* sessions so incoming packets can be sorted out
*/
struct l2tp_tunnel_cfg {
int debug; /* bitmask of debug message
* categories */
enum l2tp_encap_type encap;
/* Used only for kernel-created sockets */
struct in_addr local_ip;
struct in_addr peer_ip;
#if IS_ENABLED(CONFIG_IPV6)
struct in6_addr *local_ip6;
struct in6_addr *peer_ip6;
#endif
u16 local_udp_port;
u16 peer_udp_port;
unsigned int use_udp_checksums:1,
udp6_zero_tx_checksums:1,
udp6_zero_rx_checksums:1;
};
struct l2tp_tunnel {
int magic; /* Should be L2TP_TUNNEL_MAGIC */
struct rcu_head rcu;
rwlock_t hlist_lock; /* protect session_hlist */
struct hlist_head session_hlist[L2TP_HASH_SIZE];
/* 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 */
enum l2tp_encap_type encap;
struct l2tp_stats stats;
struct list_head list; /* Keep a list of all tunnels */
struct net *l2tp_net; /* the net we belong to */
refcount_t ref_count;
#ifdef CONFIG_DEBUG_FS
void (*show)(struct seq_file *m, void *arg);
#endif
int (*recv_payload_hook)(struct sk_buff *skb);
void (*old_sk_destruct)(struct sock *);
struct sock *sock; /* Parent socket */
int fd; /* Parent fd, if tunnel socket
* was created by userspace */
#if IS_ENABLED(CONFIG_IPV6)
bool v4mapped;
#endif
struct work_struct del_work;
uint8_t priv[0]; /* private data */
};
struct l2tp_nl_cmd_ops {
int (*session_create)(struct net *net, u32 tunnel_id, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg);
int (*session_delete)(struct l2tp_session *session);
};
static inline void *l2tp_tunnel_priv(struct l2tp_tunnel *tunnel)
{
return &tunnel->priv[0];
}
static inline void *l2tp_session_priv(struct l2tp_session *session)
{
return &session->priv[0];
}
static inline struct l2tp_tunnel *l2tp_sock_to_tunnel(struct sock *sk)
{
struct l2tp_tunnel *tunnel;
if (sk == NULL)
return NULL;
sock_hold(sk);
tunnel = (struct l2tp_tunnel *)(sk->sk_user_data);
if (tunnel == NULL) {
sock_put(sk);
goto out;
}
BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
out:
return tunnel;
}
struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id);
struct l2tp_session *l2tp_session_get(const struct net *net,
struct l2tp_tunnel *tunnel,
u32 session_id, bool do_ref);
struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth,
bool do_ref);
struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
const char *ifname,
bool do_ref);
struct l2tp_tunnel *l2tp_tunnel_find(const struct net *net, u32 tunnel_id);
struct l2tp_tunnel *l2tp_tunnel_find_nth(const struct net *net, int nth);
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);
void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel);
int 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);
void __l2tp_session_unhash(struct l2tp_session *session);
int l2tp_session_delete(struct l2tp_session *session);
void l2tp_session_free(struct l2tp_session *session);
void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
unsigned char *ptr, unsigned char *optr, u16 hdrflags,
int length, int (*payload_hook)(struct sk_buff *skb));
int l2tp_session_queue_purge(struct l2tp_session *session);
int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb);
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))
kfree_rcu(tunnel, rcu);
}
/* Session reference counts. Incremented when code obtains a reference
* to a session.
*/
static inline void l2tp_session_inc_refcount_1(struct l2tp_session *session)
{
refcount_inc(&session->ref_count);
}
static inline void l2tp_session_dec_refcount_1(struct l2tp_session *session)
{
if (refcount_dec_and_test(&session->ref_count))
l2tp_session_free(session);
}
#ifdef L2TP_REFCNT_DEBUG
#define l2tp_session_inc_refcount(_s) \
do { \
pr_debug("l2tp_session_inc_refcount: %s:%d %s: cnt=%d\n", \
__func__, __LINE__, (_s)->name, \
refcount_read(&_s->ref_count)); \
l2tp_session_inc_refcount_1(_s); \
} while (0)
#define l2tp_session_dec_refcount(_s) \
do { \
pr_debug("l2tp_session_dec_refcount: %s:%d %s: cnt=%d\n", \
__func__, __LINE__, (_s)->name, \
refcount_read(&_s->ref_count)); \
l2tp_session_dec_refcount_1(_s); \
} while (0)
#else
#define l2tp_session_inc_refcount(s) l2tp_session_inc_refcount_1(s)
#define l2tp_session_dec_refcount(s) l2tp_session_dec_refcount_1(s)
#endif
#define l2tp_printk(ptr, type, func, fmt, ...) \
do { \
if (((ptr)->debug) & (type)) \
func(fmt, ##__VA_ARGS__); \
} while (0)
#define l2tp_warn(ptr, type, fmt, ...) \
l2tp_printk(ptr, type, pr_warn, fmt, ##__VA_ARGS__)
#define l2tp_info(ptr, type, fmt, ...) \
l2tp_printk(ptr, type, pr_info, fmt, ##__VA_ARGS__)
#define l2tp_dbg(ptr, type, fmt, ...) \
l2tp_printk(ptr, type, pr_debug, fmt, ##__VA_ARGS__)
#define MODULE_ALIAS_L2TP_PWTYPE(type) \
MODULE_ALIAS("net-l2tp-type-" __stringify(type))
#endif /* _L2TP_CORE_H_ */
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