FreeBSD/Linux Kernel Cross Reference
sys/sys/unpcb.h

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * Copyright (c) 1982, 1986, 1989, 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)unpcb.h     8.1 (Berkeley) 6/2/93
     * $FreeBSD$
     */
    
    #ifndef _SYS_UNPCB_H_
    #define _SYS_UNPCB_H_
    
    typedef uint64_t unp_gen_t;
    
    #if defined(_KERNEL) || defined(_WANT_UNPCB)
    #include <sys/queue.h>
    #include <sys/ucred.h>
    
    /*
     * Protocol control block for an active
     * instance of a UNIX internal protocol.
     *
     * A socket may be associated with a vnode in the
     * filesystem.  If so, the unp_vnode pointer holds
     * a reference count to this vnode, which should be irele'd
     * when the socket goes away.
     *
     * A socket may be connected to another socket, in which
     * case the control block of the socket to which it is connected
     * is given by unp_conn.
     *
     * A socket may be referenced by a number of sockets (e.g. several
     * sockets may be connected to a datagram socket.)  These sockets
     * are in a linked list starting with unp_refs, linked through
     * unp_nextref and null-terminated.  Note that a socket may be referenced
     * by a number of other sockets and may also reference a socket (not
     * necessarily one which is referencing it).  This generates
     * the need for unp_refs and unp_nextref to be separate fields.
     *
     * Stream sockets keep copies of receive sockbuf sb_cc and sb_mbcnt
     * so that changes in the sockbuf may be computed to modify
     * back pressure on the sender accordingly.
     *
     * Locking key:
     * (a) Atomic
     * (c) Constant
     * (g) Locked using linkage lock
     * (l) Locked using list lock
     * (p) Locked using pcb lock
     */
    LIST_HEAD(unp_head, unpcb);
    
    struct unpcb {
            /* Cache line 1 */
            struct  mtx unp_mtx;            /* PCB mutex */
            struct  unpcb *unp_conn;        /* (p) connected socket */
            volatile u_int unp_refcount;    /* (a, p) atomic refcount */
            short   unp_flags;              /* (p) PCB flags */
            short   unp_gcflag;             /* (g) Garbage collector flags */
            struct  sockaddr_un *unp_addr;  /* (p) bound address of socket */
            struct  socket *unp_socket;     /* (c) pointer back to socket */
            /* Cache line 2 */
            u_int   unp_pairbusy;           /* (p) threads acquiring peer locks */
            struct  vnode *unp_vnode;       /* (p) associated file if applicable */
            struct  xucred unp_peercred;    /* (p) peer credentials if applicable */
            LIST_ENTRY(unpcb) unp_reflink;  /* (l) link in unp_refs list */
            LIST_ENTRY(unpcb) unp_link;     /* (g) glue on list of all PCBs */
            struct  unp_head unp_refs;      /* (l) referencing socket linked list */
            unp_gen_t unp_gencnt;           /* (g) generation count of this item */
            struct  file *unp_file;         /* (g) back-pointer to file for gc */
            u_int   unp_msgcount;           /* (g) references from message queue */
            ino_t   unp_ino;                /* (g) fake inode number */
            LIST_ENTRY(unpcb) unp_dead;     /* (g) link in dead list */
    } __aligned(CACHE_LINE_SIZE);
   
   /*
    * Flags in unp_flags.
    *
    * UNP_HAVEPC - indicates that the unp_peercred member is filled in
    * and is really the credentials of the connected peer.  This is used
    * to determine whether the contents should be sent to the user or
    * not.
    */
   #define UNP_HAVEPC                      0x001
   #define UNP_WANTCRED                    0x004   /* credentials wanted */
   #define UNP_CONNWAIT                    0x008   /* connect blocks until accepted */
   
   /*
    * These flags are used to handle non-atomicity in connect() and bind()
    * operations on a socket: in particular, to avoid races between multiple
    * threads or processes operating simultaneously on the same socket.
    */
   #define UNP_CONNECTING                  0x010   /* Currently connecting. */
   #define UNP_BINDING                     0x020   /* Currently binding. */
   #define UNP_WAITING                     0x040   /* Peer state is changing. */
   
   /*
    * Flags in unp_gcflag.
    */
   #define UNPGC_REF                       0x1     /* unpcb has external ref. */
   #define UNPGC_DEAD                      0x2     /* unpcb might be dead. */
   #define UNPGC_SCANNED                   0x4     /* Has been scanned. */
   #define UNPGC_IGNORE_RIGHTS             0x8     /* Attached rights are freed */
   
   #define sotounpcb(so)   ((struct unpcb *)((so)->so_pcb))
   
   #endif  /* _KERNEL || _WANT_UNPCB */
   
   /*
    * UNPCB structure exported to user-land via sysctl(3).
    *
    * Fields prefixed with "xu_" are unique to the export structure, and fields
    * with "unp_" or other prefixes match corresponding fields of 'struct unpcb'.
    *
    * Legend:
    * (s) - used by userland utilities in src
    * (p) - used by utilities in ports
    * (3) - is known to be used by third party software not in ports
    * (n) - no known usage
    *
    * Evil hack: declare only if sys/socketvar.h have been included.
    */
   #ifdef  _SYS_SOCKETVAR_H_
   struct xunpcb {
           ksize_t         xu_len;                 /* length of this structure */
           kvaddr_t        xu_unpp;                /* to help netstat, fstat */
           kvaddr_t        unp_vnode;              /* (s) */
           kvaddr_t        unp_conn;               /* (s) */
           kvaddr_t        xu_firstref;            /* (s) */
           kvaddr_t        xu_nextref;             /* (s) */
           unp_gen_t       unp_gencnt;             /* (s) */
           int64_t         xu_spare64[8];
           int32_t         xu_spare32[8];
           union {
                   struct  sockaddr_un xu_addr;    /* our bound address */
                   char    xu_dummy1[256];
           };
           union {
                   struct  sockaddr_un xu_caddr;   /* their bound address */
                   char    xu_dummy2[256];
           };
           struct xsocket  xu_socket;
   } __aligned(MAX(8, sizeof(void *)));
   
   struct xunpgen {
           ksize_t xug_len;
           u_int   xug_count;
           unp_gen_t xug_gen;
           so_gen_t xug_sogen;
   } __aligned(8);;
   #endif /* _SYS_SOCKETVAR_H_ */
   
   #if defined(_KERNEL)
   struct thread;
   
   /* In uipc_userreq.c */
   void
   unp_copy_peercred(struct thread *td, struct unpcb *client_unp,
       struct unpcb *server_unp, struct unpcb *listen_unp);
   #endif
   
   #endif /* _SYS_UNPCB_H_ */

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