linux/include/net/request_sock.h
Martin KaFai Lau 267cf9fa43 tcp: bpf: Optionally store mac header in TCP_SAVE_SYN
This patch is adapted from Eric's patch in an earlier discussion [1].

The TCP_SAVE_SYN currently only stores the network header and
tcp header.  This patch allows it to optionally store
the mac header also if the setsockopt's optval is 2.

It requires one more bit for the "save_syn" bit field in tcp_sock.
This patch achieves this by moving the syn_smc bit next to the is_mptcp.
The syn_smc is currently used with the TCP experimental option.  Since
syn_smc is only used when CONFIG_SMC is enabled, this patch also puts
the "IS_ENABLED(CONFIG_SMC)" around it like the is_mptcp did
with "IS_ENABLED(CONFIG_MPTCP)".

The mac_hdrlen is also stored in the "struct saved_syn"
to allow a quick offset from the bpf prog if it chooses to start
getting from the network header or the tcp header.

[1]: https://lore.kernel.org/netdev/CANn89iLJNWh6bkH7DNhy_kmcAexuUCccqERqe7z2QsvPhGrYPQ@mail.gmail.com/

Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/bpf/20200820190123.2886935-1-kafai@fb.com
2020-08-24 14:35:00 -07:00

240 lines
6.5 KiB
C

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* NET Generic infrastructure for Network protocols.
*
* Definitions for request_sock
*
* Authors: Arnaldo Carvalho de Melo <acme@conectiva.com.br>
*
* From code originally in include/net/tcp.h
*/
#ifndef _REQUEST_SOCK_H
#define _REQUEST_SOCK_H
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/types.h>
#include <linux/bug.h>
#include <linux/refcount.h>
#include <net/sock.h>
struct request_sock;
struct sk_buff;
struct dst_entry;
struct proto;
struct request_sock_ops {
int family;
unsigned int obj_size;
struct kmem_cache *slab;
char *slab_name;
int (*rtx_syn_ack)(const struct sock *sk,
struct request_sock *req);
void (*send_ack)(const struct sock *sk, struct sk_buff *skb,
struct request_sock *req);
void (*send_reset)(const struct sock *sk,
struct sk_buff *skb);
void (*destructor)(struct request_sock *req);
void (*syn_ack_timeout)(const struct request_sock *req);
};
int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req);
struct saved_syn {
u32 mac_hdrlen;
u32 network_hdrlen;
u32 tcp_hdrlen;
u8 data[];
};
/* struct request_sock - mini sock to represent a connection request
*/
struct request_sock {
struct sock_common __req_common;
#define rsk_refcnt __req_common.skc_refcnt
#define rsk_hash __req_common.skc_hash
#define rsk_listener __req_common.skc_listener
#define rsk_window_clamp __req_common.skc_window_clamp
#define rsk_rcv_wnd __req_common.skc_rcv_wnd
struct request_sock *dl_next;
u16 mss;
u8 num_retrans; /* number of retransmits */
u8 syncookie:1; /* syncookie: encode tcpopts in timestamp */
u8 num_timeout:7; /* number of timeouts */
u32 ts_recent;
struct timer_list rsk_timer;
const struct request_sock_ops *rsk_ops;
struct sock *sk;
struct saved_syn *saved_syn;
u32 secid;
u32 peer_secid;
};
static inline struct request_sock *inet_reqsk(const struct sock *sk)
{
return (struct request_sock *)sk;
}
static inline struct sock *req_to_sk(struct request_sock *req)
{
return (struct sock *)req;
}
static inline struct request_sock *
reqsk_alloc(const struct request_sock_ops *ops, struct sock *sk_listener,
bool attach_listener)
{
struct request_sock *req;
req = kmem_cache_alloc(ops->slab, GFP_ATOMIC | __GFP_NOWARN);
if (!req)
return NULL;
req->rsk_listener = NULL;
if (attach_listener) {
if (unlikely(!refcount_inc_not_zero(&sk_listener->sk_refcnt))) {
kmem_cache_free(ops->slab, req);
return NULL;
}
req->rsk_listener = sk_listener;
}
req->rsk_ops = ops;
req_to_sk(req)->sk_prot = sk_listener->sk_prot;
sk_node_init(&req_to_sk(req)->sk_node);
sk_tx_queue_clear(req_to_sk(req));
req->saved_syn = NULL;
req->num_timeout = 0;
req->num_retrans = 0;
req->sk = NULL;
refcount_set(&req->rsk_refcnt, 0);
return req;
}
static inline void __reqsk_free(struct request_sock *req)
{
req->rsk_ops->destructor(req);
if (req->rsk_listener)
sock_put(req->rsk_listener);
kfree(req->saved_syn);
kmem_cache_free(req->rsk_ops->slab, req);
}
static inline void reqsk_free(struct request_sock *req)
{
WARN_ON_ONCE(refcount_read(&req->rsk_refcnt) != 0);
__reqsk_free(req);
}
static inline void reqsk_put(struct request_sock *req)
{
if (refcount_dec_and_test(&req->rsk_refcnt))
reqsk_free(req);
}
/*
* For a TCP Fast Open listener -
* lock - protects the access to all the reqsk, which is co-owned by
* the listener and the child socket.
* qlen - pending TFO requests (still in TCP_SYN_RECV).
* max_qlen - max TFO reqs allowed before TFO is disabled.
*
* XXX (TFO) - ideally these fields can be made as part of "listen_sock"
* structure above. But there is some implementation difficulty due to
* listen_sock being part of request_sock_queue hence will be freed when
* a listener is stopped. But TFO related fields may continue to be
* accessed even after a listener is closed, until its sk_refcnt drops
* to 0 implying no more outstanding TFO reqs. One solution is to keep
* listen_opt around until sk_refcnt drops to 0. But there is some other
* complexity that needs to be resolved. E.g., a listener can be disabled
* temporarily through shutdown()->tcp_disconnect(), and re-enabled later.
*/
struct fastopen_queue {
struct request_sock *rskq_rst_head; /* Keep track of past TFO */
struct request_sock *rskq_rst_tail; /* requests that caused RST.
* This is part of the defense
* against spoofing attack.
*/
spinlock_t lock;
int qlen; /* # of pending (TCP_SYN_RECV) reqs */
int max_qlen; /* != 0 iff TFO is currently enabled */
struct tcp_fastopen_context __rcu *ctx; /* cipher context for cookie */
};
/** struct request_sock_queue - queue of request_socks
*
* @rskq_accept_head - FIFO head of established children
* @rskq_accept_tail - FIFO tail of established children
* @rskq_defer_accept - User waits for some data after accept()
*
*/
struct request_sock_queue {
spinlock_t rskq_lock;
u8 rskq_defer_accept;
u32 synflood_warned;
atomic_t qlen;
atomic_t young;
struct request_sock *rskq_accept_head;
struct request_sock *rskq_accept_tail;
struct fastopen_queue fastopenq; /* Check max_qlen != 0 to determine
* if TFO is enabled.
*/
};
void reqsk_queue_alloc(struct request_sock_queue *queue);
void reqsk_fastopen_remove(struct sock *sk, struct request_sock *req,
bool reset);
static inline bool reqsk_queue_empty(const struct request_sock_queue *queue)
{
return READ_ONCE(queue->rskq_accept_head) == NULL;
}
static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue,
struct sock *parent)
{
struct request_sock *req;
spin_lock_bh(&queue->rskq_lock);
req = queue->rskq_accept_head;
if (req) {
sk_acceptq_removed(parent);
WRITE_ONCE(queue->rskq_accept_head, req->dl_next);
if (queue->rskq_accept_head == NULL)
queue->rskq_accept_tail = NULL;
}
spin_unlock_bh(&queue->rskq_lock);
return req;
}
static inline void reqsk_queue_removed(struct request_sock_queue *queue,
const struct request_sock *req)
{
if (req->num_timeout == 0)
atomic_dec(&queue->young);
atomic_dec(&queue->qlen);
}
static inline void reqsk_queue_added(struct request_sock_queue *queue)
{
atomic_inc(&queue->young);
atomic_inc(&queue->qlen);
}
static inline int reqsk_queue_len(const struct request_sock_queue *queue)
{
return atomic_read(&queue->qlen);
}
static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
{
return atomic_read(&queue->young);
}
#endif /* _REQUEST_SOCK_H */