From: Jerry Chu Date: Fri, 31 Aug 2012 12:29:11 +0000 (+0000) Subject: tcp: TCP Fast Open Server - header & support functions X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=104671636897;p=openwrt%2Fstaging%2Fblogic.git tcp: TCP Fast Open Server - header & support functions This patch adds all the necessary data structure and support functions to implement TFO server side. It also documents a number of flags for the sysctl_tcp_fastopen knob, and adds a few Linux extension MIBs. In addition, it includes the following: 1. a new TCP_FASTOPEN socket option an application must call to supply a max backlog allowed in order to enable TFO on its listener. 2. A number of key data structures: "fastopen_rsk" in tcp_sock - for a big socket to access its request_sock for retransmission and ack processing purpose. It is non-NULL iff 3WHS not completed. "fastopenq" in request_sock_queue - points to a per Fast Open listener data structure "fastopen_queue" to keep track of qlen (# of outstanding Fast Open requests) and max_qlen, among other things. "listener" in tcp_request_sock - to point to the original listener for book-keeping purpose, i.e., to maintain qlen against max_qlen as part of defense against IP spoofing attack. 3. various data structure and functions, many in tcp_fastopen.c, to support server side Fast Open cookie operations, including /proc/sys/net/ipv4/tcp_fastopen_key to allow manual rekeying. Signed-off-by: H.K. Jerry Chu Cc: Yuchung Cheng Cc: Neal Cardwell Cc: Eric Dumazet Cc: Tom Herbert Signed-off-by: David S. Miller --- diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index d64e53124b8c..c7fc10724948 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -467,16 +467,31 @@ tcp_syncookies - BOOLEAN tcp_fastopen - INTEGER Enable TCP Fast Open feature (draft-ietf-tcpm-fastopen) to send data in the opening SYN packet. To use this feature, the client application - must not use connect(). Instead, it should use sendmsg() or sendto() - with MSG_FASTOPEN flag which performs a TCP handshake automatically. - - The values (bitmap) are: - 1: Enables sending data in the opening SYN on the client - 5: Enables sending data in the opening SYN on the client regardless - of cookie availability. + must use sendmsg() or sendto() with MSG_FASTOPEN flag rather than + connect() to perform a TCP handshake automatically. + + The values (bitmap) are + 1: Enables sending data in the opening SYN on the client. + 2: Enables TCP Fast Open on the server side, i.e., allowing data in + a SYN packet to be accepted and passed to the application before + 3-way hand shake finishes. + 4: Send data in the opening SYN regardless of cookie availability and + without a cookie option. + 0x100: Accept SYN data w/o validating the cookie. + 0x200: Accept data-in-SYN w/o any cookie option present. + 0x400/0x800: Enable Fast Open on all listeners regardless of the + TCP_FASTOPEN socket option. The two different flags designate two + different ways of setting max_qlen without the TCP_FASTOPEN socket + option. Default: 0 + Note that the client & server side Fast Open flags (1 and 2 + respectively) must be also enabled before the rest of flags can take + effect. + + See include/net/tcp.h and the code for more details. + tcp_syn_retries - INTEGER Number of times initial SYNs for an active TCP connection attempt will be retransmitted. Should not be higher than 255. Default value diff --git a/include/linux/snmp.h b/include/linux/snmp.h index ad6e3a6bf9fb..fdfba235f9f1 100644 --- a/include/linux/snmp.h +++ b/include/linux/snmp.h @@ -241,6 +241,10 @@ enum LINUX_MIB_TCPCHALLENGEACK, /* TCPChallengeACK */ LINUX_MIB_TCPSYNCHALLENGE, /* TCPSYNChallenge */ LINUX_MIB_TCPFASTOPENACTIVE, /* TCPFastOpenActive */ + LINUX_MIB_TCPFASTOPENPASSIVE, /* TCPFastOpenPassive*/ + LINUX_MIB_TCPFASTOPENPASSIVEFAIL, /* TCPFastOpenPassiveFail */ + LINUX_MIB_TCPFASTOPENLISTENOVERFLOW, /* TCPFastOpenListenOverflow */ + LINUX_MIB_TCPFASTOPENCOOKIEREQD, /* TCPFastOpenCookieReqd */ __LINUX_MIB_MAX }; diff --git a/include/linux/tcp.h b/include/linux/tcp.h index eb125a4c30b3..ae46df590629 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -110,6 +110,7 @@ enum { #define TCP_REPAIR_QUEUE 20 #define TCP_QUEUE_SEQ 21 #define TCP_REPAIR_OPTIONS 22 +#define TCP_FASTOPEN 23 /* Enable FastOpen on listeners */ struct tcp_repair_opt { __u32 opt_code; @@ -246,6 +247,7 @@ static inline unsigned int tcp_optlen(const struct sk_buff *skb) /* TCP Fast Open */ #define TCP_FASTOPEN_COOKIE_MIN 4 /* Min Fast Open Cookie size in bytes */ #define TCP_FASTOPEN_COOKIE_MAX 16 /* Max Fast Open Cookie size in bytes */ +#define TCP_FASTOPEN_COOKIE_SIZE 8 /* the size employed by this impl. */ /* TCP Fast Open Cookie as stored in memory */ struct tcp_fastopen_cookie { @@ -312,9 +314,14 @@ struct tcp_request_sock { /* Only used by TCP MD5 Signature so far. */ const struct tcp_request_sock_ops *af_specific; #endif + struct sock *listener; /* needed for TFO */ u32 rcv_isn; u32 snt_isn; u32 snt_synack; /* synack sent time */ + u32 rcv_nxt; /* the ack # by SYNACK. For + * FastOpen it's the seq# + * after data-in-SYN. + */ }; static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req) @@ -505,14 +512,18 @@ struct tcp_sock { struct tcp_md5sig_info __rcu *md5sig_info; #endif -/* TCP fastopen related information */ - struct tcp_fastopen_request *fastopen_req; - /* When the cookie options are generated and exchanged, then this * object holds a reference to them (cookie_values->kref). Also * contains related tcp_cookie_transactions fields. */ struct tcp_cookie_values *cookie_values; + +/* TCP fastopen related information */ + struct tcp_fastopen_request *fastopen_req; + /* fastopen_rsk points to request_sock that resulted in this big + * socket. Used to retransmit SYNACKs etc. + */ + struct request_sock *fastopen_rsk; }; enum tsq_flags { @@ -552,6 +563,34 @@ static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk) return (struct tcp_timewait_sock *)sk; } +static inline bool tcp_passive_fastopen(const struct sock *sk) +{ + return (sk->sk_state == TCP_SYN_RECV && + tcp_sk(sk)->fastopen_rsk != NULL); +} + +static inline bool fastopen_cookie_present(struct tcp_fastopen_cookie *foc) +{ + return foc->len != -1; +} + +static inline int fastopen_init_queue(struct sock *sk, int backlog) +{ + struct request_sock_queue *queue = + &inet_csk(sk)->icsk_accept_queue; + + if (queue->fastopenq == NULL) { + queue->fastopenq = kzalloc( + sizeof(struct fastopen_queue), + sk->sk_allocation); + if (queue->fastopenq == NULL) + return -ENOMEM; + spin_lock_init(&queue->fastopenq->lock); + } + queue->fastopenq->max_qlen = backlog; + return 0; +} + #endif /* __KERNEL__ */ #endif /* _LINUX_TCP_H */ diff --git a/include/net/request_sock.h b/include/net/request_sock.h index 4c0766e201e3..c3cdd6c9f448 100644 --- a/include/net/request_sock.h +++ b/include/net/request_sock.h @@ -106,6 +106,34 @@ struct listen_sock { struct request_sock *syn_table[0]; }; +/* + * 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 request_sock_queue - queue of request_socks * * @rskq_accept_head - FIFO head of established children @@ -129,6 +157,12 @@ struct request_sock_queue { u8 rskq_defer_accept; /* 3 bytes hole, try to pack */ struct listen_sock *listen_opt; + struct fastopen_queue *fastopenq; /* This is non-NULL iff TFO has been + * enabled on this listener. Check + * max_qlen != 0 in fastopen_queue + * to determine if TFO is enabled + * right at this moment. + */ }; extern int reqsk_queue_alloc(struct request_sock_queue *queue, @@ -136,6 +170,8 @@ extern int reqsk_queue_alloc(struct request_sock_queue *queue, extern void __reqsk_queue_destroy(struct request_sock_queue *queue); extern void reqsk_queue_destroy(struct request_sock_queue *queue); +extern void reqsk_fastopen_remove(struct sock *sk, + struct request_sock *req, bool reset); static inline struct request_sock * reqsk_queue_yank_acceptq(struct request_sock_queue *queue) diff --git a/include/net/tcp.h b/include/net/tcp.h index 0fca06f16463..9f8821e3293a 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -224,8 +224,24 @@ extern void tcp_time_wait(struct sock *sk, int state, int timeo); /* Bit Flags for sysctl_tcp_fastopen */ #define TFO_CLIENT_ENABLE 1 +#define TFO_SERVER_ENABLE 2 #define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */ +/* Process SYN data but skip cookie validation */ +#define TFO_SERVER_COOKIE_NOT_CHKED 0x100 +/* Accept SYN data w/o any cookie option */ +#define TFO_SERVER_COOKIE_NOT_REQD 0x200 + +/* Force enable TFO on all listeners, i.e., not requiring the + * TCP_FASTOPEN socket option. SOCKOPT1/2 determine how to set max_qlen. + */ +#define TFO_SERVER_WO_SOCKOPT1 0x400 +#define TFO_SERVER_WO_SOCKOPT2 0x800 +/* Always create TFO child sockets on a TFO listener even when + * cookie/data not present. (For testing purpose!) + */ +#define TFO_SERVER_ALWAYS 0x1000 + extern struct inet_timewait_death_row tcp_death_row; /* sysctl variables for tcp */ @@ -421,12 +437,6 @@ extern void tcp_metrics_init(void); extern bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, bool paws_check); extern bool tcp_remember_stamp(struct sock *sk); extern bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw); -extern void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, - struct tcp_fastopen_cookie *cookie, - int *syn_loss, unsigned long *last_syn_loss); -extern void tcp_fastopen_cache_set(struct sock *sk, u16 mss, - struct tcp_fastopen_cookie *cookie, - bool syn_lost); extern void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst); extern void tcp_disable_fack(struct tcp_sock *tp); extern void tcp_close(struct sock *sk, long timeout); @@ -537,6 +547,7 @@ extern void tcp_send_delayed_ack(struct sock *sk); extern void tcp_cwnd_application_limited(struct sock *sk); extern void tcp_resume_early_retransmit(struct sock *sk); extern void tcp_rearm_rto(struct sock *sk); +extern void tcp_reset(struct sock *sk); /* tcp_timer.c */ extern void tcp_init_xmit_timers(struct sock *); @@ -586,6 +597,7 @@ extern int tcp_mtu_to_mss(struct sock *sk, int pmtu); extern int tcp_mss_to_mtu(struct sock *sk, int mss); extern void tcp_mtup_init(struct sock *sk); extern void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt); +extern void tcp_init_buffer_space(struct sock *sk); static inline void tcp_bound_rto(const struct sock *sk) { @@ -1104,6 +1116,7 @@ static inline void tcp_openreq_init(struct request_sock *req, req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */ req->cookie_ts = 0; tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq; + tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->seq + 1; req->mss = rx_opt->mss_clamp; req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0; ireq->tstamp_ok = rx_opt->tstamp_ok; @@ -1308,15 +1321,34 @@ extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, const struct tcp_md5sig_key *key); +/* From tcp_fastopen.c */ +extern void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, + struct tcp_fastopen_cookie *cookie, + int *syn_loss, unsigned long *last_syn_loss); +extern void tcp_fastopen_cache_set(struct sock *sk, u16 mss, + struct tcp_fastopen_cookie *cookie, + bool syn_lost); struct tcp_fastopen_request { /* Fast Open cookie. Size 0 means a cookie request */ struct tcp_fastopen_cookie cookie; struct msghdr *data; /* data in MSG_FASTOPEN */ u16 copied; /* queued in tcp_connect() */ }; - void tcp_free_fastopen_req(struct tcp_sock *tp); +extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx; +int tcp_fastopen_reset_cipher(void *key, unsigned int len); +void tcp_fastopen_cookie_gen(__be32 addr, struct tcp_fastopen_cookie *foc); + +#define TCP_FASTOPEN_KEY_LENGTH 16 + +/* Fastopen key context */ +struct tcp_fastopen_context { + struct crypto_cipher __rcu *tfm; + __u8 key[TCP_FASTOPEN_KEY_LENGTH]; + struct rcu_head rcu; +}; + /* write queue abstraction */ static inline void tcp_write_queue_purge(struct sock *sk) { diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c index 957acd12250b..8de53e1ddd54 100644 --- a/net/ipv4/proc.c +++ b/net/ipv4/proc.c @@ -263,6 +263,10 @@ static const struct snmp_mib snmp4_net_list[] = { SNMP_MIB_ITEM("TCPChallengeACK", LINUX_MIB_TCPCHALLENGEACK), SNMP_MIB_ITEM("TCPSYNChallenge", LINUX_MIB_TCPSYNCHALLENGE), SNMP_MIB_ITEM("TCPFastOpenActive", LINUX_MIB_TCPFASTOPENACTIVE), + SNMP_MIB_ITEM("TCPFastOpenPassive", LINUX_MIB_TCPFASTOPENPASSIVE), + SNMP_MIB_ITEM("TCPFastOpenPassiveFail", LINUX_MIB_TCPFASTOPENPASSIVEFAIL), + SNMP_MIB_ITEM("TCPFastOpenListenOverflow", LINUX_MIB_TCPFASTOPENLISTENOVERFLOW), + SNMP_MIB_ITEM("TCPFastOpenCookieReqd", LINUX_MIB_TCPFASTOPENCOOKIEREQD), SNMP_MIB_SENTINEL }; diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c index 3e78c79b5586..9205e492dc9d 100644 --- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -232,6 +232,45 @@ static int ipv4_tcp_mem(ctl_table *ctl, int write, return 0; } +int proc_tcp_fastopen_key(ctl_table *ctl, int write, void __user *buffer, + size_t *lenp, loff_t *ppos) +{ + ctl_table tbl = { .maxlen = (TCP_FASTOPEN_KEY_LENGTH * 2 + 10) }; + struct tcp_fastopen_context *ctxt; + int ret; + u32 user_key[4]; /* 16 bytes, matching TCP_FASTOPEN_KEY_LENGTH */ + + tbl.data = kmalloc(tbl.maxlen, GFP_KERNEL); + if (!tbl.data) + return -ENOMEM; + + rcu_read_lock(); + ctxt = rcu_dereference(tcp_fastopen_ctx); + if (ctxt) + memcpy(user_key, ctxt->key, TCP_FASTOPEN_KEY_LENGTH); + rcu_read_unlock(); + + snprintf(tbl.data, tbl.maxlen, "%08x-%08x-%08x-%08x", + user_key[0], user_key[1], user_key[2], user_key[3]); + ret = proc_dostring(&tbl, write, buffer, lenp, ppos); + + if (write && ret == 0) { + if (sscanf(tbl.data, "%x-%x-%x-%x", user_key, user_key + 1, + user_key + 2, user_key + 3) != 4) { + ret = -EINVAL; + goto bad_key; + } + tcp_fastopen_reset_cipher(user_key, TCP_FASTOPEN_KEY_LENGTH); + } + +bad_key: + pr_debug("proc FO key set 0x%x-%x-%x-%x <- 0x%s: %u\n", + user_key[0], user_key[1], user_key[2], user_key[3], + (char *)tbl.data, ret); + kfree(tbl.data); + return ret; +} + static struct ctl_table ipv4_table[] = { { .procname = "tcp_timestamps", @@ -385,6 +424,12 @@ static struct ctl_table ipv4_table[] = { .mode = 0644, .proc_handler = proc_dointvec, }, + { + .procname = "tcp_fastopen_key", + .mode = 0600, + .maxlen = ((TCP_FASTOPEN_KEY_LENGTH * 2) + 10), + .proc_handler = proc_tcp_fastopen_key, + }, { .procname = "tcp_tw_recycle", .data = &tcp_death_row.sysctl_tw_recycle, diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c index a7f729c409d7..8f7ef0ad80e5 100644 --- a/net/ipv4/tcp_fastopen.c +++ b/net/ipv4/tcp_fastopen.c @@ -1,10 +1,91 @@ +#include #include #include +#include +#include +#include +#include +#include +#include -int sysctl_tcp_fastopen; +int sysctl_tcp_fastopen __read_mostly; + +struct tcp_fastopen_context __rcu *tcp_fastopen_ctx; + +static DEFINE_SPINLOCK(tcp_fastopen_ctx_lock); + +static void tcp_fastopen_ctx_free(struct rcu_head *head) +{ + struct tcp_fastopen_context *ctx = + container_of(head, struct tcp_fastopen_context, rcu); + crypto_free_cipher(ctx->tfm); + kfree(ctx); +} + +int tcp_fastopen_reset_cipher(void *key, unsigned int len) +{ + int err; + struct tcp_fastopen_context *ctx, *octx; + + ctx = kmalloc(sizeof(*ctx), GFP_KERNEL); + if (!ctx) + return -ENOMEM; + ctx->tfm = crypto_alloc_cipher("aes", 0, 0); + + if (IS_ERR(ctx->tfm)) { + err = PTR_ERR(ctx->tfm); +error: kfree(ctx); + pr_err("TCP: TFO aes cipher alloc error: %d\n", err); + return err; + } + err = crypto_cipher_setkey(ctx->tfm, key, len); + if (err) { + pr_err("TCP: TFO cipher key error: %d\n", err); + crypto_free_cipher(ctx->tfm); + goto error; + } + memcpy(ctx->key, key, len); + + spin_lock(&tcp_fastopen_ctx_lock); + + octx = rcu_dereference_protected(tcp_fastopen_ctx, + lockdep_is_held(&tcp_fastopen_ctx_lock)); + rcu_assign_pointer(tcp_fastopen_ctx, ctx); + spin_unlock(&tcp_fastopen_ctx_lock); + + if (octx) + call_rcu(&octx->rcu, tcp_fastopen_ctx_free); + return err; +} + +/* Computes the fastopen cookie for the peer. + * The peer address is a 128 bits long (pad with zeros for IPv4). + * + * The caller must check foc->len to determine if a valid cookie + * has been generated successfully. +*/ +void tcp_fastopen_cookie_gen(__be32 addr, struct tcp_fastopen_cookie *foc) +{ + __be32 peer_addr[4] = { addr, 0, 0, 0 }; + struct tcp_fastopen_context *ctx; + + rcu_read_lock(); + ctx = rcu_dereference(tcp_fastopen_ctx); + if (ctx) { + crypto_cipher_encrypt_one(ctx->tfm, + foc->val, + (__u8 *)peer_addr); + foc->len = TCP_FASTOPEN_COOKIE_SIZE; + } + rcu_read_unlock(); +} static int __init tcp_fastopen_init(void) { + __u8 key[TCP_FASTOPEN_KEY_LENGTH]; + + get_random_bytes(key, sizeof(key)); + tcp_fastopen_reset_cipher(key, sizeof(key)); return 0; } diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index ce4ffe9ed556..d47d5fe8f3f0 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -378,7 +378,7 @@ static void tcp_fixup_rcvbuf(struct sock *sk) /* 4. Try to fixup all. It is made immediately after connection enters * established state. */ -static void tcp_init_buffer_space(struct sock *sk) +void tcp_init_buffer_space(struct sock *sk) { struct tcp_sock *tp = tcp_sk(sk); int maxwin; @@ -4038,7 +4038,7 @@ static inline bool tcp_sequence(const struct tcp_sock *tp, u32 seq, u32 end_seq) } /* When we get a reset we do this. */ -static void tcp_reset(struct sock *sk) +void tcp_reset(struct sock *sk) { /* We want the right error as BSD sees it (and indeed as we do). */ switch (sk->sk_state) {