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dccp.h
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1 #ifndef _DCCP_H
2 #define _DCCP_H
3 /*
4  * net/dccp/dccp.h
5  *
6  * An implementation of the DCCP protocol
7  * Copyright (c) 2005 Arnaldo Carvalho de Melo <[email protected]>
8  * Copyright (c) 2005-6 Ian McDonald <[email protected]>
9  *
10  * This program is free software; you can redistribute it and/or modify it
11  * under the terms of the GNU General Public License version 2 as
12  * published by the Free Software Foundation.
13  */
14 
15 #include <linux/dccp.h>
16 #include <linux/ktime.h>
17 #include <net/snmp.h>
18 #include <net/sock.h>
19 #include <net/tcp.h>
20 #include "ackvec.h"
21 
22 /*
23  * DCCP - specific warning and debugging macros.
24  */
25 #define DCCP_WARN(fmt, a...) LIMIT_NETDEBUG(KERN_WARNING "%s: " fmt, \
26  __func__, ##a)
27 #define DCCP_CRIT(fmt, a...) printk(KERN_CRIT fmt " at %s:%d/%s()\n", ##a, \
28  __FILE__, __LINE__, __func__)
29 #define DCCP_BUG(a...) do { DCCP_CRIT("BUG: " a); dump_stack(); } while(0)
30 #define DCCP_BUG_ON(cond) do { if (unlikely((cond) != 0)) \
31  DCCP_BUG("\"%s\" holds (exception!)", \
32  __stringify(cond)); \
33  } while (0)
34 
35 #define DCCP_PRINTK(enable, fmt, args...) do { if (enable) \
36  printk(fmt, ##args); \
37  } while(0)
38 #define DCCP_PR_DEBUG(enable, fmt, a...) DCCP_PRINTK(enable, KERN_DEBUG \
39  "%s: " fmt, __func__, ##a)
40 
41 #ifdef CONFIG_IP_DCCP_DEBUG
42 extern bool dccp_debug;
43 #define dccp_pr_debug(format, a...) DCCP_PR_DEBUG(dccp_debug, format, ##a)
44 #define dccp_pr_debug_cat(format, a...) DCCP_PRINTK(dccp_debug, format, ##a)
45 #define dccp_debug(fmt, a...) dccp_pr_debug_cat(KERN_DEBUG fmt, ##a)
46 #else
47 #define dccp_pr_debug(format, a...)
48 #define dccp_pr_debug_cat(format, a...)
49 #define dccp_debug(format, a...)
50 #endif
51 
52 extern struct inet_hashinfo dccp_hashinfo;
53 
54 extern struct percpu_counter dccp_orphan_count;
55 
56 extern void dccp_time_wait(struct sock *sk, int state, int timeo);
57 
58 /*
59  * Set safe upper bounds for header and option length. Since Data Offset is 8
60  * bits (RFC 4340, sec. 5.1), the total header length can never be more than
61  * 4 * 255 = 1020 bytes. The largest possible header length is 28 bytes (X=1):
62  * - DCCP-Response with ACK Subheader and 4 bytes of Service code OR
63  * - DCCP-Reset with ACK Subheader and 4 bytes of Reset Code fields
64  * Hence a safe upper bound for the maximum option length is 1020-28 = 992
65  */
66 #define MAX_DCCP_SPECIFIC_HEADER (255 * sizeof(uint32_t))
67 #define DCCP_MAX_PACKET_HDR 28
68 #define DCCP_MAX_OPT_LEN (MAX_DCCP_SPECIFIC_HEADER - DCCP_MAX_PACKET_HDR)
69 #define MAX_DCCP_HEADER (MAX_DCCP_SPECIFIC_HEADER + MAX_HEADER)
70 
71 /* Upper bound for initial feature-negotiation overhead (padded to 32 bits) */
72 #define DCCP_FEATNEG_OVERHEAD (32 * sizeof(uint32_t))
73 
74 #define DCCP_TIMEWAIT_LEN (60 * HZ) /* how long to wait to destroy TIME-WAIT
75  * state, about 60 seconds */
76 
77 /* RFC 1122, 4.2.3.1 initial RTO value */
78 #define DCCP_TIMEOUT_INIT ((unsigned int)(3 * HZ))
79 
80 /*
81  * The maximum back-off value for retransmissions. This is needed for
82  * - retransmitting client-Requests (sec. 8.1.1),
83  * - retransmitting Close/CloseReq when closing (sec. 8.3),
84  * - feature-negotiation retransmission (sec. 6.6.3),
85  * - Acks in client-PARTOPEN state (sec. 8.1.5).
86  */
87 #define DCCP_RTO_MAX ((unsigned int)(64 * HZ))
88 
89 /*
90  * RTT sampling: sanity bounds and fallback RTT value from RFC 4340, section 3.4
91  */
92 #define DCCP_SANE_RTT_MIN 100
93 #define DCCP_FALLBACK_RTT (USEC_PER_SEC / 5)
94 #define DCCP_SANE_RTT_MAX (3 * USEC_PER_SEC)
95 
96 /* sysctl variables for DCCP */
97 extern int sysctl_dccp_request_retries;
98 extern int sysctl_dccp_retries1;
99 extern int sysctl_dccp_retries2;
100 extern int sysctl_dccp_tx_qlen;
101 extern int sysctl_dccp_sync_ratelimit;
102 
103 /*
104  * 48-bit sequence number arithmetic (signed and unsigned)
105  */
106 #define INT48_MIN 0x800000000000LL /* 2^47 */
107 #define UINT48_MAX 0xFFFFFFFFFFFFLL /* 2^48 - 1 */
108 #define COMPLEMENT48(x) (0x1000000000000LL - (x)) /* 2^48 - x */
109 #define TO_SIGNED48(x) (((x) < INT48_MIN)? (x) : -COMPLEMENT48( (x)))
110 #define TO_UNSIGNED48(x) (((x) >= 0)? (x) : COMPLEMENT48(-(x)))
111 #define ADD48(a, b) (((a) + (b)) & UINT48_MAX)
112 #define SUB48(a, b) ADD48((a), COMPLEMENT48(b))
113 
114 static inline void dccp_set_seqno(u64 *seqno, u64 value)
115 {
116  *seqno = value & UINT48_MAX;
117 }
118 
119 static inline void dccp_inc_seqno(u64 *seqno)
120 {
121  *seqno = ADD48(*seqno, 1);
122 }
123 
124 /* signed mod-2^48 distance: pos. if seqno1 < seqno2, neg. if seqno1 > seqno2 */
125 static inline s64 dccp_delta_seqno(const u64 seqno1, const u64 seqno2)
126 {
127  u64 delta = SUB48(seqno2, seqno1);
128 
129  return TO_SIGNED48(delta);
130 }
131 
132 /* is seq1 < seq2 ? */
133 static inline int before48(const u64 seq1, const u64 seq2)
134 {
135  return (s64)((seq2 << 16) - (seq1 << 16)) > 0;
136 }
137 
138 /* is seq1 > seq2 ? */
139 #define after48(seq1, seq2) before48(seq2, seq1)
140 
141 /* is seq2 <= seq1 <= seq3 ? */
142 static inline int between48(const u64 seq1, const u64 seq2, const u64 seq3)
143 {
144  return (seq3 << 16) - (seq2 << 16) >= (seq1 << 16) - (seq2 << 16);
145 }
146 
147 static inline u64 max48(const u64 seq1, const u64 seq2)
148 {
149  return after48(seq1, seq2) ? seq1 : seq2;
150 }
151 
158 static inline u64 dccp_loss_count(const u64 s1, const u64 s2, const u64 ndp)
159 {
160  s64 delta = dccp_delta_seqno(s1, s2);
161 
162  WARN_ON(delta < 0);
163  delta -= ndp + 1;
164 
165  return delta > 0 ? delta : 0;
166 }
167 
171 static inline bool dccp_loss_free(const u64 s1, const u64 s2, const u64 ndp)
172 {
173  return dccp_loss_count(s1, s2, ndp) == 0;
174 }
175 
176 enum {
177  DCCP_MIB_NUM = 0,
178  DCCP_MIB_ACTIVEOPENS, /* ActiveOpens */
179  DCCP_MIB_ESTABRESETS, /* EstabResets */
180  DCCP_MIB_CURRESTAB, /* CurrEstab */
181  DCCP_MIB_OUTSEGS, /* OutSegs */
182  DCCP_MIB_OUTRSTS,
183  DCCP_MIB_ABORTONTIMEOUT,
184  DCCP_MIB_TIMEOUTS,
185  DCCP_MIB_ABORTFAILED,
186  DCCP_MIB_PASSIVEOPENS,
187  DCCP_MIB_ATTEMPTFAILS,
188  DCCP_MIB_OUTDATAGRAMS,
189  DCCP_MIB_INERRS,
190  DCCP_MIB_OPTMANDATORYERROR,
191  DCCP_MIB_INVALIDOPT,
192  __DCCP_MIB_MAX
193 };
194 
195 #define DCCP_MIB_MAX __DCCP_MIB_MAX
196 struct dccp_mib {
197  unsigned long mibs[DCCP_MIB_MAX];
198 };
199 
200 DECLARE_SNMP_STAT(struct dccp_mib, dccp_statistics);
201 #define DCCP_INC_STATS(field) SNMP_INC_STATS(dccp_statistics, field)
202 #define DCCP_INC_STATS_BH(field) SNMP_INC_STATS_BH(dccp_statistics, field)
203 #define DCCP_DEC_STATS(field) SNMP_DEC_STATS(dccp_statistics, field)
204 
205 /*
206  * Checksumming routines
207  */
208 static inline unsigned int dccp_csum_coverage(const struct sk_buff *skb)
209 {
210  const struct dccp_hdr* dh = dccp_hdr(skb);
211 
212  if (dh->dccph_cscov == 0)
213  return skb->len;
214  return (dh->dccph_doff + dh->dccph_cscov - 1) * sizeof(u32);
215 }
216 
217 static inline void dccp_csum_outgoing(struct sk_buff *skb)
218 {
219  unsigned int cov = dccp_csum_coverage(skb);
220 
221  if (cov >= skb->len)
222  dccp_hdr(skb)->dccph_cscov = 0;
223 
224  skb->csum = skb_checksum(skb, 0, (cov > skb->len)? skb->len : cov, 0);
225 }
226 
227 extern void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb);
228 
229 extern int dccp_retransmit_skb(struct sock *sk);
230 
231 extern void dccp_send_ack(struct sock *sk);
232 extern void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
233  struct request_sock *rsk);
234 
235 extern void dccp_send_sync(struct sock *sk, const u64 seq,
236  const enum dccp_pkt_type pkt_type);
237 
238 /*
239  * TX Packet Dequeueing Interface
240  */
241 extern void dccp_qpolicy_push(struct sock *sk, struct sk_buff *skb);
242 extern bool dccp_qpolicy_full(struct sock *sk);
243 extern void dccp_qpolicy_drop(struct sock *sk, struct sk_buff *skb);
244 extern struct sk_buff *dccp_qpolicy_top(struct sock *sk);
245 extern struct sk_buff *dccp_qpolicy_pop(struct sock *sk);
246 extern bool dccp_qpolicy_param_ok(struct sock *sk, __be32 param);
247 
248 /*
249  * TX Packet Output and TX Timers
250  */
251 extern void dccp_write_xmit(struct sock *sk);
252 extern void dccp_write_space(struct sock *sk);
253 extern void dccp_flush_write_queue(struct sock *sk, long *time_budget);
254 
255 extern void dccp_init_xmit_timers(struct sock *sk);
256 static inline void dccp_clear_xmit_timers(struct sock *sk)
257 {
258  inet_csk_clear_xmit_timers(sk);
259 }
260 
261 extern unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu);
262 
263 extern const char *dccp_packet_name(const int type);
264 
265 extern void dccp_set_state(struct sock *sk, const int state);
266 extern void dccp_done(struct sock *sk);
267 
268 extern int dccp_reqsk_init(struct request_sock *rq, struct dccp_sock const *dp,
269  struct sk_buff const *skb);
270 
271 extern int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
272 
273 extern struct sock *dccp_create_openreq_child(struct sock *sk,
274  const struct request_sock *req,
275  const struct sk_buff *skb);
276 
277 extern int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
278 
279 extern struct sock *dccp_v4_request_recv_sock(struct sock *sk,
280  struct sk_buff *skb,
281  struct request_sock *req,
282  struct dst_entry *dst);
283 extern struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
284  struct request_sock *req,
285  struct request_sock **prev);
286 
287 extern int dccp_child_process(struct sock *parent, struct sock *child,
288  struct sk_buff *skb);
289 extern int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
290  struct dccp_hdr *dh, unsigned int len);
291 extern int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
292  const struct dccp_hdr *dh, const unsigned int len);
293 
294 extern int dccp_init_sock(struct sock *sk, const __u8 ctl_sock_initialized);
295 extern void dccp_destroy_sock(struct sock *sk);
296 
297 extern void dccp_close(struct sock *sk, long timeout);
298 extern struct sk_buff *dccp_make_response(struct sock *sk,
299  struct dst_entry *dst,
300  struct request_sock *req);
301 
302 extern int dccp_connect(struct sock *sk);
303 extern int dccp_disconnect(struct sock *sk, int flags);
304 extern int dccp_getsockopt(struct sock *sk, int level, int optname,
305  char __user *optval, int __user *optlen);
306 extern int dccp_setsockopt(struct sock *sk, int level, int optname,
307  char __user *optval, unsigned int optlen);
308 #ifdef CONFIG_COMPAT
309 extern int compat_dccp_getsockopt(struct sock *sk,
310  int level, int optname,
311  char __user *optval, int __user *optlen);
312 extern int compat_dccp_setsockopt(struct sock *sk,
313  int level, int optname,
314  char __user *optval, unsigned int optlen);
315 #endif
316 extern int dccp_ioctl(struct sock *sk, int cmd, unsigned long arg);
317 extern int dccp_sendmsg(struct kiocb *iocb, struct sock *sk,
318  struct msghdr *msg, size_t size);
319 extern int dccp_recvmsg(struct kiocb *iocb, struct sock *sk,
320  struct msghdr *msg, size_t len, int nonblock,
321  int flags, int *addr_len);
322 extern void dccp_shutdown(struct sock *sk, int how);
323 extern int inet_dccp_listen(struct socket *sock, int backlog);
324 extern unsigned int dccp_poll(struct file *file, struct socket *sock,
325  poll_table *wait);
326 extern int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr,
327  int addr_len);
328 
329 extern struct sk_buff *dccp_ctl_make_reset(struct sock *sk,
330  struct sk_buff *skb);
331 extern int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code);
332 extern void dccp_send_close(struct sock *sk, const int active);
333 extern int dccp_invalid_packet(struct sk_buff *skb);
334 extern u32 dccp_sample_rtt(struct sock *sk, long delta);
335 
336 static inline int dccp_bad_service_code(const struct sock *sk,
337  const __be32 service)
338 {
339  const struct dccp_sock *dp = dccp_sk(sk);
340 
341  if (dp->dccps_service == service)
342  return 0;
343  return !dccp_list_has_service(dp->dccps_service_list, service);
344 }
345 
358 struct dccp_skb_cb {
359  union {
360  struct inet_skb_parm h4;
361 #if IS_ENABLED(CONFIG_IPV6)
362  struct inet6_skb_parm h6;
363 #endif
364  } header;
365  __u8 dccpd_type:4;
366  __u8 dccpd_ccval:4;
367  __u8 dccpd_reset_code,
368  dccpd_reset_data[3];
369  __u16 dccpd_opt_len;
370  __u64 dccpd_seq;
371  __u64 dccpd_ack_seq;
372 };
373 
374 #define DCCP_SKB_CB(__skb) ((struct dccp_skb_cb *)&((__skb)->cb[0]))
375 
376 /* RFC 4340, sec. 7.7 */
377 static inline int dccp_non_data_packet(const struct sk_buff *skb)
378 {
379  const __u8 type = DCCP_SKB_CB(skb)->dccpd_type;
380 
381  return type == DCCP_PKT_ACK ||
382  type == DCCP_PKT_CLOSE ||
383  type == DCCP_PKT_CLOSEREQ ||
384  type == DCCP_PKT_RESET ||
385  type == DCCP_PKT_SYNC ||
386  type == DCCP_PKT_SYNCACK;
387 }
388 
389 /* RFC 4340, sec. 7.7 */
390 static inline int dccp_data_packet(const struct sk_buff *skb)
391 {
392  const __u8 type = DCCP_SKB_CB(skb)->dccpd_type;
393 
394  return type == DCCP_PKT_DATA ||
395  type == DCCP_PKT_DATAACK ||
396  type == DCCP_PKT_REQUEST ||
397  type == DCCP_PKT_RESPONSE;
398 }
399 
400 static inline int dccp_packet_without_ack(const struct sk_buff *skb)
401 {
402  const __u8 type = DCCP_SKB_CB(skb)->dccpd_type;
403 
404  return type == DCCP_PKT_DATA || type == DCCP_PKT_REQUEST;
405 }
406 
407 #define DCCP_PKT_WITHOUT_ACK_SEQ (UINT48_MAX << 2)
408 
409 static inline void dccp_hdr_set_seq(struct dccp_hdr *dh, const u64 gss)
410 {
411  struct dccp_hdr_ext *dhx = (struct dccp_hdr_ext *)((void *)dh +
412  sizeof(*dh));
413  dh->dccph_seq2 = 0;
414  dh->dccph_seq = htons((gss >> 32) & 0xfffff);
415  dhx->dccph_seq_low = htonl(gss & 0xffffffff);
416 }
417 
418 static inline void dccp_hdr_set_ack(struct dccp_hdr_ack_bits *dhack,
419  const u64 gsr)
420 {
421  dhack->dccph_reserved1 = 0;
422  dhack->dccph_ack_nr_high = htons(gsr >> 32);
423  dhack->dccph_ack_nr_low = htonl(gsr & 0xffffffff);
424 }
425 
426 static inline void dccp_update_gsr(struct sock *sk, u64 seq)
427 {
428  struct dccp_sock *dp = dccp_sk(sk);
429 
430  if (after48(seq, dp->dccps_gsr))
431  dp->dccps_gsr = seq;
432  /* Sequence validity window depends on remote Sequence Window (7.5.1) */
433  dp->dccps_swl = SUB48(ADD48(dp->dccps_gsr, 1), dp->dccps_r_seq_win / 4);
434  /*
435  * Adjust SWL so that it is not below ISR. In contrast to RFC 4340,
436  * 7.5.1 we perform this check beyond the initial handshake: W/W' are
437  * always > 32, so for the first W/W' packets in the lifetime of a
438  * connection we always have to adjust SWL.
439  * A second reason why we are doing this is that the window depends on
440  * the feature-remote value of Sequence Window: nothing stops the peer
441  * from updating this value while we are busy adjusting SWL for the
442  * first W packets (we would have to count from scratch again then).
443  * Therefore it is safer to always make sure that the Sequence Window
444  * is not artificially extended by a peer who grows SWL downwards by
445  * continually updating the feature-remote Sequence-Window.
446  * If sequence numbers wrap it is bad luck. But that will take a while
447  * (48 bit), and this measure prevents Sequence-number attacks.
448  */
449  if (before48(dp->dccps_swl, dp->dccps_isr))
450  dp->dccps_swl = dp->dccps_isr;
451  dp->dccps_swh = ADD48(dp->dccps_gsr, (3 * dp->dccps_r_seq_win) / 4);
452 }
453 
454 static inline void dccp_update_gss(struct sock *sk, u64 seq)
455 {
456  struct dccp_sock *dp = dccp_sk(sk);
457 
458  dp->dccps_gss = seq;
459  /* Ack validity window depends on local Sequence Window value (7.5.1) */
460  dp->dccps_awl = SUB48(ADD48(dp->dccps_gss, 1), dp->dccps_l_seq_win);
461  /* Adjust AWL so that it is not below ISS - see comment above for SWL */
462  if (before48(dp->dccps_awl, dp->dccps_iss))
463  dp->dccps_awl = dp->dccps_iss;
464  dp->dccps_awh = dp->dccps_gss;
465 }
466 
467 static inline int dccp_ackvec_pending(const struct sock *sk)
468 {
469  return dccp_sk(sk)->dccps_hc_rx_ackvec != NULL &&
470  !dccp_ackvec_is_empty(dccp_sk(sk)->dccps_hc_rx_ackvec);
471 }
472 
473 static inline int dccp_ack_pending(const struct sock *sk)
474 {
475  return dccp_ackvec_pending(sk) || inet_csk_ack_scheduled(sk);
476 }
477 
478 extern int dccp_feat_signal_nn_change(struct sock *sk, u8 feat, u64 nn_val);
479 extern int dccp_feat_finalise_settings(struct dccp_sock *dp);
480 extern int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq);
481 extern int dccp_feat_insert_opts(struct dccp_sock*, struct dccp_request_sock*,
482  struct sk_buff *skb);
483 extern int dccp_feat_activate_values(struct sock *sk, struct list_head *fn);
484 extern void dccp_feat_list_purge(struct list_head *fn_list);
485 
486 extern int dccp_insert_options(struct sock *sk, struct sk_buff *skb);
487 extern int dccp_insert_options_rsk(struct dccp_request_sock*, struct sk_buff*);
488 extern int dccp_insert_option_elapsed_time(struct sk_buff *skb, u32 elapsed);
489 extern u32 dccp_timestamp(void);
490 extern void dccp_timestamping_init(void);
491 extern int dccp_insert_option(struct sk_buff *skb, unsigned char option,
492  const void *value, unsigned char len);
493 
494 #ifdef CONFIG_SYSCTL
495 extern int dccp_sysctl_init(void);
496 extern void dccp_sysctl_exit(void);
497 #else
498 static inline int dccp_sysctl_init(void)
499 {
500  return 0;
501 }
502 
503 static inline void dccp_sysctl_exit(void)
504 {
505 }
506 #endif
507 
508 #endif /* _DCCP_H */
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