net: sctp: introduce uapi header for sctp

This patch introduces an UAPI header for the SCTP protocol,
so that we can facilitate the maintenance and development of
user land applications or libraries, in particular in terms
of header synchronization.

To not break compatibility, some fragments from lksctp-tools'
netinet/sctp.h have been carefully included, while taking care
that neither kernel nor user land breaks, so both compile fine
with this change (for lksctp-tools I tested with the old
netinet/sctp.h header and with a newly adapted one that includes
the uapi sctp header). lksctp-tools smoke test run through
successfully as well in both cases.

Suggested-by: Neil Horman <[e-mail]>
Cc: Neil Horman <[e-mail]>
Cc: Vlad Yasevich <[e-mail]>
Signed-off-by: Daniel Borkmann <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

fs/dlm/lowcomms.c

···
 #include <linux/mutex.h>
 #include <linux/sctp.h>
 #include <linux/slab.h>
+#include <linux/sctp.h>
 #include <net/sctp/sctp.h>
-#include <net/sctp/user.h>
 #include <net/ipv6.h>
 
 #include "dlm_internal.h"

include/linux/sctp.h

···
 
 #include <linux/in.h>		/* We need in_addr.  */
 #include <linux/in6.h>		/* We need in6_addr.  */
+#include <linux/skbuff.h>
 
+#include <uapi/linux/sctp.h>
 
 /* Section 3.1.  SCTP Common Header Format */
 typedef struct sctphdr {
···
 	__le32 checksum;
 } __packed sctp_sctphdr_t;
 
-#ifdef __KERNEL__
-#include <linux/skbuff.h>
-
 static inline struct sctphdr *sctp_hdr(const struct sk_buff *skb)
 {
 	return (struct sctphdr *)skb_transport_header(skb);
 }
-#endif
 
 /* Section 3.2.  Chunk Field Descriptions. */
 typedef struct sctp_chunkhdr {

include/net/sctp/constants.h

···
 
 #include <linux/sctp.h>
 #include <linux/ipv6.h> /* For ipv6hdr. */
-#include <net/sctp/user.h>
 #include <net/tcp_states.h>  /* For TCP states used in sctp_sock_state_t */
 
 /* Value used for stream negotiation. */

include/net/sctp/user.h include/uapi/linux/sctp.h

···
  *    Jon Grimm                <[e-mail]>
  *    Daisy Chang              <[e-mail]>
  *    Ryan Layer               <[e-mail]>
- *    Ardelle Fan	       <[e-mail]>
+ *    Ardelle Fan              <[e-mail]>
  *    Sridhar Samudrala        <[e-mail]>
+ *    Inaky Perez-Gonzalez     <[e-mail]>
+ *    Vlad Yasevich            <[e-mail]>
  *
  * Any bugs reported given to us we will try to fix... any fixes shared will
  * be incorporated into the next SCTP release.
  */
 
-#ifndef __net_sctp_user_h__
-#define __net_sctp_user_h__
+#ifndef _UAPI_SCTP_H
+#define _UAPI_SCTP_H
 
 #include <linux/types.h>
 #include <linux/socket.h>
···
 	SCTP_ADDR_OVER = 2,  /* Override the primary destination. */
 	SCTP_ABORT=4,        /* Send an ABORT message to the peer. */
 	SCTP_SACK_IMMEDIATELY = 8,	/* SACK should be sent without delay */
-	SCTP_EOF=MSG_FIN,    /* Initiate graceful shutdown process. */	
+	SCTP_EOF=MSG_FIN,    /* Initiate graceful shutdown process. */
 };
 
+typedef union {
+	__u8   			raw;
+	struct sctp_initmsg	init;
+	struct sctp_sndrcvinfo	sndrcv;
+} sctp_cmsg_data_t;
 
 /* These are cmsg_types.  */
 typedef enum sctp_cmsg_type {
 	SCTP_INIT,              /* 5.2.1 SCTP Initiation Structure */
+#define SCTP_INIT	SCTP_INIT
 	SCTP_SNDRCV,            /* 5.2.2 SCTP Header Information Structure */
+#define SCTP_SNDRCV	SCTP_SNDRCV
 } sctp_cmsg_t;
-
 
 /*
  * 5.3.1.1 SCTP_ASSOC_CHANGE
···
 
 enum { SCTP_PARTIAL_DELIVERY_ABORTED=0, };
 
+/*
+ * 5.3.1.8.  SCTP_AUTHENTICATION_EVENT
+ *
+ *  When a receiver is using authentication this message will provide
+ *  notifications regarding new keys being made active as well as errors.
+ */
 struct sctp_authkey_event {
 	__u16 auth_type;
 	__u16 auth_flags;
···
 enum sctp_sn_type {
 	SCTP_SN_TYPE_BASE     = (1<<15),
 	SCTP_ASSOC_CHANGE,
+#define SCTP_ASSOC_CHANGE		SCTP_ASSOC_CHANGE
 	SCTP_PEER_ADDR_CHANGE,
+#define SCTP_PEER_ADDR_CHANGE		SCTP_PEER_ADDR_CHANGE
 	SCTP_SEND_FAILED,
+#define SCTP_SEND_FAILED		SCTP_SEND_FAILED
 	SCTP_REMOTE_ERROR,
+#define SCTP_REMOTE_ERROR		SCTP_REMOTE_ERROR
 	SCTP_SHUTDOWN_EVENT,
+#define SCTP_SHUTDOWN_EVENT		SCTP_SHUTDOWN_EVENT
 	SCTP_PARTIAL_DELIVERY_EVENT,
+#define SCTP_PARTIAL_DELIVERY_EVENT	SCTP_PARTIAL_DELIVERY_EVENT
 	SCTP_ADAPTATION_INDICATION,
+#define SCTP_ADAPTATION_INDICATION	SCTP_ADAPTATION_INDICATION
 	SCTP_AUTHENTICATION_EVENT,
 #define SCTP_AUTHENTICATION_INDICATION	SCTP_AUTHENTICATION_EVENT
 	SCTP_SENDER_DRY_EVENT,
+#define SCTP_SENDER_DRY_EVENT		SCTP_SENDER_DRY_EVENT
 };
 
 /* Notification error codes used to fill up the error fields in some
···
  *
  *   The protocol parameters used to initialize and bound retransmission
  *   timeout (RTO) are tunable.  See [SCTP] for more information on how
- *   these parameters are used in RTO calculation. 
+ *   these parameters are used in RTO calculation.
  */
 struct sctp_rtoinfo {
 	sctp_assoc_t	srto_assoc_id;
···
 	sctp_assoc_t            ssp_assoc_id;
 	struct sockaddr_storage ssp_addr;
 } __attribute__((packed, aligned(4)));
+
+/* For backward compatibility use, define the old name too */
+#define sctp_setprim	sctp_prim
 
 /*
  * 7.1.11 Set Adaptation Layer Indicator (SCTP_ADAPTATION_LAYER)
···
  *
  * This option gets or sets the list of HMAC algorithms that the local
  * endpoint requires the peer to use.
-*/
+ */
+#ifndef __KERNEL__
+/* This here is only used by user space as is. It might not be a good idea
+ * to export/reveal the whole structure with reserved fields etc.
+ */
+enum {
+	SCTP_AUTH_HMAC_ID_SHA1 = 1,
+	SCTP_AUTH_HMAC_ID_SHA256 = 3,
+};
+#endif
+
 struct sctp_hmacalgo {
 	__u32		shmac_num_idents;
 	__u16		shmac_idents[];
 };
+
+/* Sadly, user and kernel space have different names for
+ * this structure member, so this is to not break anything.
+ */
+#define shmac_number_of_idents	shmac_num_idents
 
 /*
  * 7.1.20.  Set a shared key (SCTP_AUTH_KEY)
···
 	uint8_t		gauth_chunks[];
 };
 
+/* The broken spelling has been released already in lksctp-tools header,
+ * so don't break anyone, now that it's fixed.
+ */
+#define guth_number_of_chunks	gauth_number_of_chunks
+
+/* Association states.  */
+enum sctp_sstat_state {
+	SCTP_EMPTY                = 0,
+	SCTP_CLOSED               = 1,
+	SCTP_COOKIE_WAIT          = 2,
+	SCTP_COOKIE_ECHOED        = 3,
+	SCTP_ESTABLISHED          = 4,
+	SCTP_SHUTDOWN_PENDING     = 5,
+	SCTP_SHUTDOWN_SENT        = 6,
+	SCTP_SHUTDOWN_RECEIVED    = 7,
+	SCTP_SHUTDOWN_ACK_SENT    = 8,
+};
+
 /*
  * 8.2.6. Get the Current Identifiers of Associations
  *        (SCTP_GET_ASSOC_ID_LIST)
···
 
 /*
  * 8.3, 8.5 get all peer/local addresses in an association.
- * This parameter struct is used by SCTP_GET_PEER_ADDRS and 
+ * This parameter struct is used by SCTP_GET_PEER_ADDRS and
  * SCTP_GET_LOCAL_ADDRS socket options used internally to implement
- * sctp_getpaddrs() and sctp_getladdrs() API. 
+ * sctp_getpaddrs() and sctp_getladdrs() API.
  */
 struct sctp_getaddrs_old {
 	sctp_assoc_t            assoc_id;
 	int			addr_num;
+#ifdef __KERNEL__
 	struct sockaddr		__user *addrs;
+#else
+	struct sockaddr		*addrs;
+#endif
 };
+
 struct sctp_getaddrs {
 	sctp_assoc_t		assoc_id; /*input*/
 	__u32			addr_num; /*output*/
···
 	__u16 spt_pathmaxrxt;
 	__u16 spt_pathpfthld;
 };
-#endif /* __net_sctp_user_h__ */
+
+#endif /* _UAPI_SCTP_H */

include/uapi/linux/Kbuild

···
 header-y += scc.h
 header-y += sched.h
 header-y += screen_info.h
+header-y += sctp.h
 header-y += sdla.h
 header-y += seccomp.h
 header-y += securebits.h