1  /* SPDX-License-Identifier: GPL-2.0-or-later */
2  /*
3   * INET		An implementation of the TCP/IP protocol suite for the LINUX
4   *		operating system.  INET is implemented using the  BSD Socket
5   *		interface as the means of communication with the user level.
6   *
7   *		Definitions for the UDP module.
8   *
9   * Version:	@(#)udp.h	1.0.2	05/07/93
10   *
11   * Authors:	Ross Biro
12   *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
13   *
14   * Fixes:
15   *		Alan Cox	: Turned on udp checksums. I don't want to
16   *				  chase 'memory corruption' bugs that aren't!
17   */
18  #ifndef _UDP_H
19  #define _UDP_H
20  
21  #include <linux/list.h>
22  #include <linux/bug.h>
23  #include <net/inet_sock.h>
24  #include <net/gso.h>
25  #include <net/sock.h>
26  #include <net/snmp.h>
27  #include <net/ip.h>
28  #include <linux/ipv6.h>
29  #include <linux/seq_file.h>
30  #include <linux/poll.h>
31  #include <linux/indirect_call_wrapper.h>
32  
33  /**
34   *	struct udp_skb_cb  -  UDP(-Lite) private variables
35   *
36   *	@header:      private variables used by IPv4/IPv6
37   *	@cscov:       checksum coverage length (UDP-Lite only)
38   *	@partial_cov: if set indicates partial csum coverage
39   */
40  struct udp_skb_cb {
41  	union {
42  		struct inet_skb_parm	h4;
43  #if IS_ENABLED(CONFIG_IPV6)
44  		struct inet6_skb_parm	h6;
45  #endif
46  	} header;
47  	__u16		cscov;
48  	__u8		partial_cov;
49  };
50  #define UDP_SKB_CB(__skb)	((struct udp_skb_cb *)((__skb)->cb))
51  
52  /**
53   *	struct udp_hslot - UDP hash slot
54   *
55   *	@head:	head of list of sockets
56   *	@count:	number of sockets in 'head' list
57   *	@lock:	spinlock protecting changes to head/count
58   */
59  struct udp_hslot {
60  	struct hlist_head	head;
61  	int			count;
62  	spinlock_t		lock;
63  } __attribute__((aligned(2 * sizeof(long))));
64  
65  /**
66   *	struct udp_table - UDP table
67   *
68   *	@hash:	hash table, sockets are hashed on (local port)
69   *	@hash2:	hash table, sockets are hashed on (local port, local address)
70   *	@mask:	number of slots in hash tables, minus 1
71   *	@log:	log2(number of slots in hash table)
72   */
73  struct udp_table {
74  	struct udp_hslot	*hash;
75  	struct udp_hslot	*hash2;
76  	unsigned int		mask;
77  	unsigned int		log;
78  };
79  extern struct udp_table udp_table;
80  void udp_table_init(struct udp_table *, const char *);
udp_hashslot(struct udp_table * table,const struct net * net,unsigned int num)81  static inline struct udp_hslot *udp_hashslot(struct udp_table *table,
82  					     const struct net *net,
83  					     unsigned int num)
84  {
85  	return &table->hash[udp_hashfn(net, num, table->mask)];
86  }
87  /*
88   * For secondary hash, net_hash_mix() is performed before calling
89   * udp_hashslot2(), this explains difference with udp_hashslot()
90   */
udp_hashslot2(struct udp_table * table,unsigned int hash)91  static inline struct udp_hslot *udp_hashslot2(struct udp_table *table,
92  					      unsigned int hash)
93  {
94  	return &table->hash2[hash & table->mask];
95  }
96  
97  extern struct proto udp_prot;
98  
99  extern atomic_long_t udp_memory_allocated;
100  DECLARE_PER_CPU(int, udp_memory_per_cpu_fw_alloc);
101  
102  /* sysctl variables for udp */
103  extern long sysctl_udp_mem[3];
104  extern int sysctl_udp_rmem_min;
105  extern int sysctl_udp_wmem_min;
106  
107  struct sk_buff;
108  
109  /*
110   *	Generic checksumming routines for UDP(-Lite) v4 and v6
111   */
__udp_lib_checksum_complete(struct sk_buff * skb)112  static inline __sum16 __udp_lib_checksum_complete(struct sk_buff *skb)
113  {
114  	return (UDP_SKB_CB(skb)->cscov == skb->len ?
115  		__skb_checksum_complete(skb) :
116  		__skb_checksum_complete_head(skb, UDP_SKB_CB(skb)->cscov));
117  }
118  
udp_lib_checksum_complete(struct sk_buff * skb)119  static inline int udp_lib_checksum_complete(struct sk_buff *skb)
120  {
121  	return !skb_csum_unnecessary(skb) &&
122  		__udp_lib_checksum_complete(skb);
123  }
124  
125  /**
126   * 	udp_csum_outgoing  -  compute UDPv4/v6 checksum over fragments
127   * 	@sk: 	socket we are writing to
128   * 	@skb: 	sk_buff containing the filled-in UDP header
129   * 	        (checksum field must be zeroed out)
130   */
udp_csum_outgoing(struct sock * sk,struct sk_buff * skb)131  static inline __wsum udp_csum_outgoing(struct sock *sk, struct sk_buff *skb)
132  {
133  	__wsum csum = csum_partial(skb_transport_header(skb),
134  				   sizeof(struct udphdr), 0);
135  	skb_queue_walk(&sk->sk_write_queue, skb) {
136  		csum = csum_add(csum, skb->csum);
137  	}
138  	return csum;
139  }
140  
udp_csum(struct sk_buff * skb)141  static inline __wsum udp_csum(struct sk_buff *skb)
142  {
143  	__wsum csum = csum_partial(skb_transport_header(skb),
144  				   sizeof(struct udphdr), skb->csum);
145  
146  	for (skb = skb_shinfo(skb)->frag_list; skb; skb = skb->next) {
147  		csum = csum_add(csum, skb->csum);
148  	}
149  	return csum;
150  }
151  
udp_v4_check(int len,__be32 saddr,__be32 daddr,__wsum base)152  static inline __sum16 udp_v4_check(int len, __be32 saddr,
153  				   __be32 daddr, __wsum base)
154  {
155  	return csum_tcpudp_magic(saddr, daddr, len, IPPROTO_UDP, base);
156  }
157  
158  void udp_set_csum(bool nocheck, struct sk_buff *skb,
159  		  __be32 saddr, __be32 daddr, int len);
160  
udp_csum_pull_header(struct sk_buff * skb)161  static inline void udp_csum_pull_header(struct sk_buff *skb)
162  {
163  	if (!skb->csum_valid && skb->ip_summed == CHECKSUM_NONE)
164  		skb->csum = csum_partial(skb->data, sizeof(struct udphdr),
165  					 skb->csum);
166  	skb_pull_rcsum(skb, sizeof(struct udphdr));
167  	UDP_SKB_CB(skb)->cscov -= sizeof(struct udphdr);
168  }
169  
170  typedef struct sock *(*udp_lookup_t)(const struct sk_buff *skb, __be16 sport,
171  				     __be16 dport);
172  
173  void udp_v6_early_demux(struct sk_buff *skb);
174  INDIRECT_CALLABLE_DECLARE(int udpv6_rcv(struct sk_buff *));
175  
176  struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
177  				  netdev_features_t features, bool is_ipv6);
178  
udp_lib_init_sock(struct sock * sk)179  static inline void udp_lib_init_sock(struct sock *sk)
180  {
181  	struct udp_sock *up = udp_sk(sk);
182  
183  	skb_queue_head_init(&up->reader_queue);
184  	up->forward_threshold = sk->sk_rcvbuf >> 2;
185  	set_bit(SOCK_CUSTOM_SOCKOPT, &sk->sk_socket->flags);
186  }
187  
188  /* hash routines shared between UDPv4/6 and UDP-Litev4/6 */
udp_lib_hash(struct sock * sk)189  static inline int udp_lib_hash(struct sock *sk)
190  {
191  	BUG();
192  	return 0;
193  }
194  
195  void udp_lib_unhash(struct sock *sk);
196  void udp_lib_rehash(struct sock *sk, u16 new_hash);
197  
udp_lib_close(struct sock * sk,long timeout)198  static inline void udp_lib_close(struct sock *sk, long timeout)
199  {
200  	sk_common_release(sk);
201  }
202  
203  int udp_lib_get_port(struct sock *sk, unsigned short snum,
204  		     unsigned int hash2_nulladdr);
205  
206  u32 udp_flow_hashrnd(void);
207  
udp_flow_src_port(struct net * net,struct sk_buff * skb,int min,int max,bool use_eth)208  static inline __be16 udp_flow_src_port(struct net *net, struct sk_buff *skb,
209  				       int min, int max, bool use_eth)
210  {
211  	u32 hash;
212  
213  	if (min >= max) {
214  		/* Use default range */
215  		inet_get_local_port_range(net, &min, &max);
216  	}
217  
218  	hash = skb_get_hash(skb);
219  	if (unlikely(!hash)) {
220  		if (use_eth) {
221  			/* Can't find a normal hash, caller has indicated an
222  			 * Ethernet packet so use that to compute a hash.
223  			 */
224  			hash = jhash(skb->data, 2 * ETH_ALEN,
225  				     (__force u32) skb->protocol);
226  		} else {
227  			/* Can't derive any sort of hash for the packet, set
228  			 * to some consistent random value.
229  			 */
230  			hash = udp_flow_hashrnd();
231  		}
232  	}
233  
234  	/* Since this is being sent on the wire obfuscate hash a bit
235  	 * to minimize possibility that any useful information to an
236  	 * attacker is leaked. Only upper 16 bits are relevant in the
237  	 * computation for 16 bit port value.
238  	 */
239  	hash ^= hash << 16;
240  
241  	return htons((((u64) hash * (max - min)) >> 32) + min);
242  }
243  
udp_rqueue_get(struct sock * sk)244  static inline int udp_rqueue_get(struct sock *sk)
245  {
246  	return sk_rmem_alloc_get(sk) - READ_ONCE(udp_sk(sk)->forward_deficit);
247  }
248  
udp_sk_bound_dev_eq(const struct net * net,int bound_dev_if,int dif,int sdif)249  static inline bool udp_sk_bound_dev_eq(const struct net *net, int bound_dev_if,
250  				       int dif, int sdif)
251  {
252  #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
253  	return inet_bound_dev_eq(!!READ_ONCE(net->ipv4.sysctl_udp_l3mdev_accept),
254  				 bound_dev_if, dif, sdif);
255  #else
256  	return inet_bound_dev_eq(true, bound_dev_if, dif, sdif);
257  #endif
258  }
259  
260  /* net/ipv4/udp.c */
261  void udp_destruct_common(struct sock *sk);
262  void skb_consume_udp(struct sock *sk, struct sk_buff *skb, int len);
263  int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb);
264  void udp_skb_destructor(struct sock *sk, struct sk_buff *skb);
265  struct sk_buff *__skb_recv_udp(struct sock *sk, unsigned int flags, int *off,
266  			       int *err);
skb_recv_udp(struct sock * sk,unsigned int flags,int * err)267  static inline struct sk_buff *skb_recv_udp(struct sock *sk, unsigned int flags,
268  					   int *err)
269  {
270  	int off = 0;
271  
272  	return __skb_recv_udp(sk, flags, &off, err);
273  }
274  
275  int udp_v4_early_demux(struct sk_buff *skb);
276  bool udp_sk_rx_dst_set(struct sock *sk, struct dst_entry *dst);
277  int udp_err(struct sk_buff *, u32);
278  int udp_abort(struct sock *sk, int err);
279  int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len);
280  void udp_splice_eof(struct socket *sock);
281  int udp_push_pending_frames(struct sock *sk);
282  void udp_flush_pending_frames(struct sock *sk);
283  int udp_cmsg_send(struct sock *sk, struct msghdr *msg, u16 *gso_size);
284  void udp4_hwcsum(struct sk_buff *skb, __be32 src, __be32 dst);
285  int udp_rcv(struct sk_buff *skb);
286  int udp_ioctl(struct sock *sk, int cmd, int *karg);
287  int udp_init_sock(struct sock *sk);
288  int udp_pre_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
289  int __udp_disconnect(struct sock *sk, int flags);
290  int udp_disconnect(struct sock *sk, int flags);
291  __poll_t udp_poll(struct file *file, struct socket *sock, poll_table *wait);
292  struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
293  				       netdev_features_t features,
294  				       bool is_ipv6);
295  int udp_lib_getsockopt(struct sock *sk, int level, int optname,
296  		       char __user *optval, int __user *optlen);
297  int udp_lib_setsockopt(struct sock *sk, int level, int optname,
298  		       sockptr_t optval, unsigned int optlen,
299  		       int (*push_pending_frames)(struct sock *));
300  struct sock *udp4_lib_lookup(const struct net *net, __be32 saddr, __be16 sport,
301  			     __be32 daddr, __be16 dport, int dif);
302  struct sock *__udp4_lib_lookup(const struct net *net, __be32 saddr,
303  			       __be16 sport,
304  			       __be32 daddr, __be16 dport, int dif, int sdif,
305  			       struct udp_table *tbl, struct sk_buff *skb);
306  struct sock *udp4_lib_lookup_skb(const struct sk_buff *skb,
307  				 __be16 sport, __be16 dport);
308  struct sock *udp6_lib_lookup(const struct net *net,
309  			     const struct in6_addr *saddr, __be16 sport,
310  			     const struct in6_addr *daddr, __be16 dport,
311  			     int dif);
312  struct sock *__udp6_lib_lookup(const struct net *net,
313  			       const struct in6_addr *saddr, __be16 sport,
314  			       const struct in6_addr *daddr, __be16 dport,
315  			       int dif, int sdif, struct udp_table *tbl,
316  			       struct sk_buff *skb);
317  struct sock *udp6_lib_lookup_skb(const struct sk_buff *skb,
318  				 __be16 sport, __be16 dport);
319  int udp_read_skb(struct sock *sk, skb_read_actor_t recv_actor);
320  
321  /* UDP uses skb->dev_scratch to cache as much information as possible and avoid
322   * possibly multiple cache miss on dequeue()
323   */
324  struct udp_dev_scratch {
325  	/* skb->truesize and the stateless bit are embedded in a single field;
326  	 * do not use a bitfield since the compiler emits better/smaller code
327  	 * this way
328  	 */
329  	u32 _tsize_state;
330  
331  #if BITS_PER_LONG == 64
332  	/* len and the bit needed to compute skb_csum_unnecessary
333  	 * will be on cold cache lines at recvmsg time.
334  	 * skb->len can be stored on 16 bits since the udp header has been
335  	 * already validated and pulled.
336  	 */
337  	u16 len;
338  	bool is_linear;
339  	bool csum_unnecessary;
340  #endif
341  };
342  
udp_skb_scratch(struct sk_buff * skb)343  static inline struct udp_dev_scratch *udp_skb_scratch(struct sk_buff *skb)
344  {
345  	return (struct udp_dev_scratch *)&skb->dev_scratch;
346  }
347  
348  #if BITS_PER_LONG == 64
udp_skb_len(struct sk_buff * skb)349  static inline unsigned int udp_skb_len(struct sk_buff *skb)
350  {
351  	return udp_skb_scratch(skb)->len;
352  }
353  
udp_skb_csum_unnecessary(struct sk_buff * skb)354  static inline bool udp_skb_csum_unnecessary(struct sk_buff *skb)
355  {
356  	return udp_skb_scratch(skb)->csum_unnecessary;
357  }
358  
udp_skb_is_linear(struct sk_buff * skb)359  static inline bool udp_skb_is_linear(struct sk_buff *skb)
360  {
361  	return udp_skb_scratch(skb)->is_linear;
362  }
363  
364  #else
udp_skb_len(struct sk_buff * skb)365  static inline unsigned int udp_skb_len(struct sk_buff *skb)
366  {
367  	return skb->len;
368  }
369  
udp_skb_csum_unnecessary(struct sk_buff * skb)370  static inline bool udp_skb_csum_unnecessary(struct sk_buff *skb)
371  {
372  	return skb_csum_unnecessary(skb);
373  }
374  
udp_skb_is_linear(struct sk_buff * skb)375  static inline bool udp_skb_is_linear(struct sk_buff *skb)
376  {
377  	return !skb_is_nonlinear(skb);
378  }
379  #endif
380  
copy_linear_skb(struct sk_buff * skb,int len,int off,struct iov_iter * to)381  static inline int copy_linear_skb(struct sk_buff *skb, int len, int off,
382  				  struct iov_iter *to)
383  {
384  	return copy_to_iter_full(skb->data + off, len, to) ? 0 : -EFAULT;
385  }
386  
387  /*
388   * 	SNMP statistics for UDP and UDP-Lite
389   */
390  #define UDP_INC_STATS(net, field, is_udplite)		      do { \
391  	if (is_udplite) SNMP_INC_STATS((net)->mib.udplite_statistics, field);       \
392  	else		SNMP_INC_STATS((net)->mib.udp_statistics, field);  }  while(0)
393  #define __UDP_INC_STATS(net, field, is_udplite) 	      do { \
394  	if (is_udplite) __SNMP_INC_STATS((net)->mib.udplite_statistics, field);         \
395  	else		__SNMP_INC_STATS((net)->mib.udp_statistics, field);    }  while(0)
396  
397  #define __UDP6_INC_STATS(net, field, is_udplite)	    do { \
398  	if (is_udplite) __SNMP_INC_STATS((net)->mib.udplite_stats_in6, field);\
399  	else		__SNMP_INC_STATS((net)->mib.udp_stats_in6, field);  \
400  } while(0)
401  #define UDP6_INC_STATS(net, field, __lite)		    do { \
402  	if (__lite) SNMP_INC_STATS((net)->mib.udplite_stats_in6, field);  \
403  	else	    SNMP_INC_STATS((net)->mib.udp_stats_in6, field);      \
404  } while(0)
405  
406  #if IS_ENABLED(CONFIG_IPV6)
407  #define __UDPX_MIB(sk, ipv4)						\
408  ({									\
409  	ipv4 ? (IS_UDPLITE(sk) ? sock_net(sk)->mib.udplite_statistics :	\
410  				 sock_net(sk)->mib.udp_statistics) :	\
411  		(IS_UDPLITE(sk) ? sock_net(sk)->mib.udplite_stats_in6 :	\
412  				 sock_net(sk)->mib.udp_stats_in6);	\
413  })
414  #else
415  #define __UDPX_MIB(sk, ipv4)						\
416  ({									\
417  	IS_UDPLITE(sk) ? sock_net(sk)->mib.udplite_statistics :		\
418  			 sock_net(sk)->mib.udp_statistics;		\
419  })
420  #endif
421  
422  #define __UDPX_INC_STATS(sk, field) \
423  	__SNMP_INC_STATS(__UDPX_MIB(sk, (sk)->sk_family == AF_INET), field)
424  
425  #ifdef CONFIG_PROC_FS
426  struct udp_seq_afinfo {
427  	sa_family_t			family;
428  	struct udp_table		*udp_table;
429  };
430  
431  struct udp_iter_state {
432  	struct seq_net_private  p;
433  	int			bucket;
434  };
435  
436  void *udp_seq_start(struct seq_file *seq, loff_t *pos);
437  void *udp_seq_next(struct seq_file *seq, void *v, loff_t *pos);
438  void udp_seq_stop(struct seq_file *seq, void *v);
439  
440  extern const struct seq_operations udp_seq_ops;
441  extern const struct seq_operations udp6_seq_ops;
442  
443  int udp4_proc_init(void);
444  void udp4_proc_exit(void);
445  #endif /* CONFIG_PROC_FS */
446  
447  int udpv4_offload_init(void);
448  
449  void udp_init(void);
450  
451  DECLARE_STATIC_KEY_FALSE(udp_encap_needed_key);
452  void udp_encap_enable(void);
453  void udp_encap_disable(void);
454  #if IS_ENABLED(CONFIG_IPV6)
455  DECLARE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
456  void udpv6_encap_enable(void);
457  #endif
458  
udp_rcv_segment(struct sock * sk,struct sk_buff * skb,bool ipv4)459  static inline struct sk_buff *udp_rcv_segment(struct sock *sk,
460  					      struct sk_buff *skb, bool ipv4)
461  {
462  	netdev_features_t features = NETIF_F_SG;
463  	struct sk_buff *segs;
464  
465  	/* Avoid csum recalculation by skb_segment unless userspace explicitly
466  	 * asks for the final checksum values
467  	 */
468  	if (!inet_get_convert_csum(sk))
469  		features |= NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM;
470  
471  	/* UDP segmentation expects packets of type CHECKSUM_PARTIAL or
472  	 * CHECKSUM_NONE in __udp_gso_segment. UDP GRO indeed builds partial
473  	 * packets in udp_gro_complete_segment. As does UDP GSO, verified by
474  	 * udp_send_skb. But when those packets are looped in dev_loopback_xmit
475  	 * their ip_summed CHECKSUM_NONE is changed to CHECKSUM_UNNECESSARY.
476  	 * Reset in this specific case, where PARTIAL is both correct and
477  	 * required.
478  	 */
479  	if (skb->pkt_type == PACKET_LOOPBACK)
480  		skb->ip_summed = CHECKSUM_PARTIAL;
481  
482  	/* the GSO CB lays after the UDP one, no need to save and restore any
483  	 * CB fragment
484  	 */
485  	segs = __skb_gso_segment(skb, features, false);
486  	if (IS_ERR_OR_NULL(segs)) {
487  		int segs_nr = skb_shinfo(skb)->gso_segs;
488  
489  		atomic_add(segs_nr, &sk->sk_drops);
490  		SNMP_ADD_STATS(__UDPX_MIB(sk, ipv4), UDP_MIB_INERRORS, segs_nr);
491  		kfree_skb(skb);
492  		return NULL;
493  	}
494  
495  	consume_skb(skb);
496  	return segs;
497  }
498  
udp_post_segment_fix_csum(struct sk_buff * skb)499  static inline void udp_post_segment_fix_csum(struct sk_buff *skb)
500  {
501  	/* UDP-lite can't land here - no GRO */
502  	WARN_ON_ONCE(UDP_SKB_CB(skb)->partial_cov);
503  
504  	/* UDP packets generated with UDP_SEGMENT and traversing:
505  	 *
506  	 * UDP tunnel(xmit) -> veth (segmentation) -> veth (gro) -> UDP tunnel (rx)
507  	 *
508  	 * can reach an UDP socket with CHECKSUM_NONE, because
509  	 * __iptunnel_pull_header() converts CHECKSUM_PARTIAL into NONE.
510  	 * SKB_GSO_UDP_L4 or SKB_GSO_FRAGLIST packets with no UDP tunnel will
511  	 * have a valid checksum, as the GRO engine validates the UDP csum
512  	 * before the aggregation and nobody strips such info in between.
513  	 * Instead of adding another check in the tunnel fastpath, we can force
514  	 * a valid csum after the segmentation.
515  	 * Additionally fixup the UDP CB.
516  	 */
517  	UDP_SKB_CB(skb)->cscov = skb->len;
518  	if (skb->ip_summed == CHECKSUM_NONE && !skb->csum_valid)
519  		skb->csum_valid = 1;
520  }
521  
522  #ifdef CONFIG_BPF_SYSCALL
523  struct sk_psock;
524  int udp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore);
525  #endif
526  
527  #endif	/* _UDP_H */
528