sys/kern/sysv_msg.c

   1 /* $FreeBSD: src/sys/kern/sysv_msg.c,v 1.23.2.5 2002/12/31 08:54:53 maxim Exp $ */
   2 /* $DragonFly: src/sys/kern/sysv_msg.c,v 1.18 2008/01/06 16:55:51 swildner Exp $ */
   3
   4 /*
   5  * Implementation of SVID messages
   6  *
   7  * Author:  Daniel Boulet
   8  *
   9  * Copyright 1993 Daniel Boulet and RTMX Inc.
  10  *
  11  * This system call was implemented by Daniel Boulet under contract from RTMX.
  12  *
  13  * Redistribution and use in source forms, with and without modification,
  14  * are permitted provided that this entire comment appears intact.
  15  *
  16  * Redistribution in binary form may occur without any restrictions.
  17  * Obviously, it would be nice if you gave credit where credit is due
  18  * but requiring it would be too onerous.
  19  *
  20  * This software is provided ``AS IS'' without any warranties of any kind.
  21  */
  22
  23 #include "opt_sysvipc.h"
  24
  25 #include <sys/param.h>
  26 #include <sys/systm.h>
  27 #include <sys/sysproto.h>
  28 #include <sys/kernel.h>
  29 #include <sys/proc.h>
  30 #include <sys/priv.h>
  31 #include <sys/msg.h>
  32 #include <sys/sysent.h>
  33 #include <sys/sysctl.h>
  34 #include <sys/malloc.h>
  35 #include <sys/jail.h>
  36
  37 static MALLOC_DEFINE(M_MSG, "msg", "SVID compatible message queues");
  38
  39 static void msginit (void *);
  40
  41 #define MSG_DEBUG
  42 #undef MSG_DEBUG_OK
  43
  44 static void msg_freehdr (struct msg *msghdr);
  45
  46 /* XXX casting to (sy_call_t *) is bogus, as usual. */
  47 static sy_call_t *msgcalls[] = {
  48         (sy_call_t *)sys_msgctl, (sy_call_t *)sys_msgget,
  49         (sy_call_t *)sys_msgsnd, (sy_call_t *)sys_msgrcv
  50 };
  51
  52 struct msg {
  53         struct  msg *msg_next;  /* next msg in the chain */
  54         long    msg_type;       /* type of this message */
  55                                 /* >0 -> type of this message */
  56                                 /* 0 -> free header */
  57         u_short msg_ts;         /* size of this message */
  58         short   msg_spot;       /* location of start of msg in buffer */
  59 };
  60
  61
  62 #ifndef MSGSSZ
  63 #define MSGSSZ  8               /* Each segment must be 2^N long */
  64 #endif
  65 #ifndef MSGSEG
  66 #define MSGSEG  2048            /* must be less than 32767 */
  67 #endif
  68 #define MSGMAX  (MSGSSZ*MSGSEG)
  69 #ifndef MSGMNB
  70 #define MSGMNB  2048            /* max # of bytes in a queue */
  71 #endif
  72 #ifndef MSGMNI
  73 #define MSGMNI  40
  74 #endif
  75 #ifndef MSGTQL
  76 #define MSGTQL  40
  77 #endif
  78
  79 /*
  80  * Based on the configuration parameters described in an SVR2 (yes, two)
  81  * config(1m) man page.
  82  *
  83  * Each message is broken up and stored in segments that are msgssz bytes
  84  * long.  For efficiency reasons, this should be a power of two.  Also,
  85  * it doesn't make sense if it is less than 8 or greater than about 256.
  86  * Consequently, msginit in kern/sysv_msg.c checks that msgssz is a power of
  87  * two between 8 and 1024 inclusive (and panic's if it isn't).
  88  */
  89 struct msginfo msginfo = {
  90                 MSGMAX,         /* max chars in a message */
  91                 MSGMNI,         /* # of message queue identifiers */
  92                 MSGMNB,         /* max chars in a queue */
  93                 MSGTQL,         /* max messages in system */
  94                 MSGSSZ,         /* size of a message segment */
  95                                 /* (must be small power of 2 greater than 4) */
  96                 MSGSEG          /* number of message segments */
  97 };
  98
  99 /*
 100  * macros to convert between msqid_ds's and msqid's.
 101  * (specific to this implementation)
 102  */
 103 #define MSQID(ix,ds)    ((ix) & 0xffff | (((ds).msg_perm.seq << 16) & 0xffff0000))
 104 #define MSQID_IX(id)    ((id) & 0xffff)
 105 #define MSQID_SEQ(id)   (((id) >> 16) & 0xffff)
 106
 107 /*
 108  * The rest of this file is specific to this particular implementation.
 109  */
 110
 111 struct msgmap {
 112         short   next;           /* next segment in buffer */
 113                                 /* -1 -> available */
 114                                 /* 0..(MSGSEG-1) -> index of next segment */
 115 };
 116
 117 #define MSG_LOCKED      01000   /* Is this msqid_ds locked? */
 118
 119 static int nfree_msgmaps;       /* # of free map entries */
 120 static short free_msgmaps;      /* head of linked list of free map entries */
 121 static struct msg *free_msghdrs;/* list of free msg headers */
 122 static char *msgpool;           /* MSGMAX byte long msg buffer pool */
 123 static struct msgmap *msgmaps;  /* MSGSEG msgmap structures */
 124 static struct msg *msghdrs;     /* MSGTQL msg headers */
 125 static struct msqid_ds *msqids; /* MSGMNI msqid_ds struct's */
 126
 127 static void
 128 msginit(void *dummy)
 129 {
 130         int i;
 131
 132         msginfo.msgmax = msginfo.msgseg * msginfo.msgssz;
 133         msgpool = kmalloc(msginfo.msgmax, M_MSG, M_WAITOK);
 134         msgmaps = kmalloc(sizeof(struct msgmap) * msginfo.msgseg, M_MSG, M_WAITOK);
 135         msghdrs = kmalloc(sizeof(struct msg) * msginfo.msgtql, M_MSG, M_WAITOK);
 136         msqids = kmalloc(sizeof(struct msqid_ds) * msginfo.msgmni, M_MSG, M_WAITOK);
 137
 138         /*
 139          * msginfo.msgssz should be a power of two for efficiency reasons.
 140          * It is also pretty silly if msginfo.msgssz is less than 8
 141          * or greater than about 256 so ...
 142          */
 143
 144         i = 8;
 145         while (i < 1024 && i != msginfo.msgssz)
 146                 i <<= 1;
 147         if (i != msginfo.msgssz) {
 148                 kprintf("msginfo.msgssz=%d (0x%x)\n", msginfo.msgssz,
 149                     msginfo.msgssz);
 150                 panic("msginfo.msgssz not a small power of 2");
 151         }
 152
 153         if (msginfo.msgseg > 32767) {
 154                 kprintf("msginfo.msgseg=%d\n", msginfo.msgseg);
 155                 panic("msginfo.msgseg > 32767");
 156         }
 157
 158         if (msgmaps == NULL)
 159                 panic("msgmaps is NULL");
 160
 161         for (i = 0; i < msginfo.msgseg; i++) {
 162                 if (i > 0)
 163                         msgmaps[i-1].next = i;
 164                 msgmaps[i].next = -1;   /* implies entry is available */
 165         }
 166         free_msgmaps = 0;
 167         nfree_msgmaps = msginfo.msgseg;
 168
 169         if (msghdrs == NULL)
 170                 panic("msghdrs is NULL");
 171
 172         for (i = 0; i < msginfo.msgtql; i++) {
 173                 msghdrs[i].msg_type = 0;
 174                 if (i > 0)
 175                         msghdrs[i-1].msg_next = &msghdrs[i];
 176                 msghdrs[i].msg_next = NULL;
 177         }
 178         free_msghdrs = &msghdrs[0];
 179
 180         if (msqids == NULL)
 181                 panic("msqids is NULL");
 182
 183         for (i = 0; i < msginfo.msgmni; i++) {
 184                 msqids[i].msg_qbytes = 0;       /* implies entry is available */
 185                 msqids[i].msg_perm.seq = 0;     /* reset to a known value */
 186                 msqids[i].msg_perm.mode = 0;
 187         }
 188 }
 189 SYSINIT(sysv_msg, SI_SUB_SYSV_MSG, SI_ORDER_FIRST, msginit, NULL)
 190
 191 /*
 192  * Entry point for all MSG calls
 193  *
 194  * msgsys_args(int which, int a2, ...) (VARARGS)
 195  */
 196 int
 197 sys_msgsys(struct msgsys_args *uap)
 198 {
 199         struct proc *p = curproc;
 200         unsigned int which = (unsigned int)uap->which;
 201
 202         if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL)
 203                 return (ENOSYS);
 204
 205         if (which >= sizeof(msgcalls)/sizeof(msgcalls[0]))
 206                 return (EINVAL);
 207         bcopy(&uap->a2, &uap->which,
 208             sizeof(struct msgsys_args) - offsetof(struct msgsys_args, a2));
 209         return ((*msgcalls[which])(uap));
 210 }
 211
 212 static void
 213 msg_freehdr(struct msg *msghdr)
 214 {
 215         while (msghdr->msg_ts > 0) {
 216                 short next;
 217                 if (msghdr->msg_spot < 0 || msghdr->msg_spot >= msginfo.msgseg)
 218                         panic("msghdr->msg_spot out of range");
 219                 next = msgmaps[msghdr->msg_spot].next;
 220                 msgmaps[msghdr->msg_spot].next = free_msgmaps;
 221                 free_msgmaps = msghdr->msg_spot;
 222                 nfree_msgmaps++;
 223                 msghdr->msg_spot = next;
 224                 if (msghdr->msg_ts >= msginfo.msgssz)
 225                         msghdr->msg_ts -= msginfo.msgssz;
 226                 else
 227                         msghdr->msg_ts = 0;
 228         }
 229         if (msghdr->msg_spot != -1)
 230                 panic("msghdr->msg_spot != -1");
 231         msghdr->msg_next = free_msghdrs;
 232         free_msghdrs = msghdr;
 233 }
 234
 235 int
 236 sys_msgctl(struct msgctl_args *uap)
 237 {
 238         struct thread *td = curthread;
 239         struct proc *p = td->td_proc;
 240         int msqid = uap->msqid;
 241         int cmd = uap->cmd;
 242         struct msqid_ds *user_msqptr = uap->buf;
 243         int rval, eval;
 244         struct msqid_ds msqbuf;
 245         struct msqid_ds *msqptr;
 246
 247 #ifdef MSG_DEBUG_OK
 248         kprintf("call to msgctl(%d, %d, 0x%x)\n", msqid, cmd, user_msqptr);
 249 #endif
 250
 251         if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL)
 252                 return (ENOSYS);
 253
 254         msqid = IPCID_TO_IX(msqid);
 255
 256         if (msqid < 0 || msqid >= msginfo.msgmni) {
 257 #ifdef MSG_DEBUG_OK
 258                 kprintf("msqid (%d) out of range (0<=msqid<%d)\n", msqid,
 259                     msginfo.msgmni);
 260 #endif
 261                 return(EINVAL);
 262         }
 263
 264         msqptr = &msqids[msqid];
 265
 266         if (msqptr->msg_qbytes == 0) {
 267 #ifdef MSG_DEBUG_OK
 268                 kprintf("no such msqid\n");
 269 #endif
 270                 return(EINVAL);
 271         }
 272         if (msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) {
 273 #ifdef MSG_DEBUG_OK
 274                 kprintf("wrong sequence number\n");
 275 #endif
 276                 return(EINVAL);
 277         }
 278
 279         eval = 0;
 280         rval = 0;
 281
 282         switch (cmd) {
 283
 284         case IPC_RMID:
 285         {
 286                 struct msg *msghdr;
 287                 if ((eval = ipcperm(p, &msqptr->msg_perm, IPC_M)))
 288                         return(eval);
 289                 /* Free the message headers */
 290                 msghdr = msqptr->msg_first;
 291                 while (msghdr != NULL) {
 292                         struct msg *msghdr_tmp;
 293
 294                         /* Free the segments of each message */
 295                         msqptr->msg_cbytes -= msghdr->msg_ts;
 296                         msqptr->msg_qnum--;
 297                         msghdr_tmp = msghdr;
 298                         msghdr = msghdr->msg_next;
 299                         msg_freehdr(msghdr_tmp);
 300                 }
 301
 302                 if (msqptr->msg_cbytes != 0)
 303                         panic("msg_cbytes is screwed up");
 304                 if (msqptr->msg_qnum != 0)
 305                         panic("msg_qnum is screwed up");
 306
 307                 msqptr->msg_qbytes = 0; /* Mark it as free */
 308
 309                 wakeup((caddr_t)msqptr);
 310         }
 311
 312                 break;
 313
 314         case IPC_SET:
 315                 if ((eval = ipcperm(p, &msqptr->msg_perm, IPC_M)))
 316                         return(eval);
 317                 if ((eval = copyin(user_msqptr, &msqbuf, sizeof(msqbuf))) != 0)
 318                         return(eval);
 319                 if (msqbuf.msg_qbytes > msqptr->msg_qbytes) {
 320                         eval = priv_check(td, PRIV_ROOT);
 321                         if (eval)
 322                                 return(eval);
 323                 }
 324                 if (msqbuf.msg_qbytes > msginfo.msgmnb) {
 325 #ifdef MSG_DEBUG_OK
 326                         kprintf("can't increase msg_qbytes beyond %d (truncating)\n",
 327                             msginfo.msgmnb);
 328 #endif
 329                         msqbuf.msg_qbytes = msginfo.msgmnb;     /* silently restrict qbytes to system limit */
 330                 }
 331                 if (msqbuf.msg_qbytes == 0) {
 332 #ifdef MSG_DEBUG_OK
 333                         kprintf("can't reduce msg_qbytes to 0\n");
 334 #endif
 335                         return(EINVAL);         /* non-standard errno! */
 336                 }
 337                 msqptr->msg_perm.uid = msqbuf.msg_perm.uid;     /* change the owner */
 338                 msqptr->msg_perm.gid = msqbuf.msg_perm.gid;     /* change the owner */
 339                 msqptr->msg_perm.mode = (msqptr->msg_perm.mode & ~0777) |
 340                     (msqbuf.msg_perm.mode & 0777);
 341                 msqptr->msg_qbytes = msqbuf.msg_qbytes;
 342                 msqptr->msg_ctime = time_second;
 343                 break;
 344
 345         case IPC_STAT:
 346                 if ((eval = ipcperm(p, &msqptr->msg_perm, IPC_R))) {
 347 #ifdef MSG_DEBUG_OK
 348                         kprintf("requester doesn't have read access\n");
 349 #endif
 350                         return(eval);
 351                 }
 352                 eval = copyout((caddr_t)msqptr, user_msqptr,
 353                     sizeof(struct msqid_ds));
 354                 break;
 355
 356         default:
 357 #ifdef MSG_DEBUG_OK
 358                 kprintf("invalid command %d\n", cmd);
 359 #endif
 360                 return(EINVAL);
 361         }
 362
 363         if (eval == 0)
 364                 uap->sysmsg_result = rval;
 365         return(eval);
 366 }
 367
 368 int
 369 sys_msgget(struct msgget_args *uap)
 370 {
 371         struct proc *p = curproc;
 372         int msqid, eval;
 373         int key = uap->key;
 374         int msgflg = uap->msgflg;
 375         struct ucred *cred = p->p_ucred;
 376         struct msqid_ds *msqptr = NULL;
 377
 378 #ifdef MSG_DEBUG_OK
 379         kprintf("msgget(0x%x, 0%o)\n", key, msgflg);
 380 #endif
 381
 382         if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL)
 383                 return (ENOSYS);
 384
 385         if (key != IPC_PRIVATE) {
 386                 for (msqid = 0; msqid < msginfo.msgmni; msqid++) {
 387                         msqptr = &msqids[msqid];
 388                         if (msqptr->msg_qbytes != 0 &&
 389                             msqptr->msg_perm.key == key)
 390                                 break;
 391                 }
 392                 if (msqid < msginfo.msgmni) {
 393 #ifdef MSG_DEBUG_OK
 394                         kprintf("found public key\n");
 395 #endif
 396                         if ((msgflg & IPC_CREAT) && (msgflg & IPC_EXCL)) {
 397 #ifdef MSG_DEBUG_OK
 398                                 kprintf("not exclusive\n");
 399 #endif
 400                                 return(EEXIST);
 401                         }
 402                         if ((eval = ipcperm(p, &msqptr->msg_perm, msgflg & 0700 ))) {
 403 #ifdef MSG_DEBUG_OK
 404                                 kprintf("requester doesn't have 0%o access\n",
 405                                     msgflg & 0700);
 406 #endif
 407                                 return(eval);
 408                         }
 409                         goto found;
 410                 }
 411         }
 412
 413 #ifdef MSG_DEBUG_OK
 414         kprintf("need to allocate the msqid_ds\n");
 415 #endif
 416         if (key == IPC_PRIVATE || (msgflg & IPC_CREAT)) {
 417                 for (msqid = 0; msqid < msginfo.msgmni; msqid++) {
 418                         /*
 419                          * Look for an unallocated and unlocked msqid_ds.
 420                          * msqid_ds's can be locked by msgsnd or msgrcv while
 421                          * they are copying the message in/out.  We can't
 422                          * re-use the entry until they release it.
 423                          */
 424                         msqptr = &msqids[msqid];
 425                         if (msqptr->msg_qbytes == 0 &&
 426                             (msqptr->msg_perm.mode & MSG_LOCKED) == 0)
 427                                 break;
 428                 }
 429                 if (msqid == msginfo.msgmni) {
 430 #ifdef MSG_DEBUG_OK
 431                         kprintf("no more msqid_ds's available\n");
 432 #endif
 433                         return(ENOSPC);
 434                 }
 435 #ifdef MSG_DEBUG_OK
 436                 kprintf("msqid %d is available\n", msqid);
 437 #endif
 438                 msqptr->msg_perm.key = key;
 439                 msqptr->msg_perm.cuid = cred->cr_uid;
 440                 msqptr->msg_perm.uid = cred->cr_uid;
 441                 msqptr->msg_perm.cgid = cred->cr_gid;
 442                 msqptr->msg_perm.gid = cred->cr_gid;
 443                 msqptr->msg_perm.mode = (msgflg & 0777);
 444                 /* Make sure that the returned msqid is unique */
 445                 msqptr->msg_perm.seq = (msqptr->msg_perm.seq + 1) & 0x7fff;
 446                 msqptr->msg_first = NULL;
 447                 msqptr->msg_last = NULL;
 448                 msqptr->msg_cbytes = 0;
 449                 msqptr->msg_qnum = 0;
 450                 msqptr->msg_qbytes = msginfo.msgmnb;
 451                 msqptr->msg_lspid = 0;
 452                 msqptr->msg_lrpid = 0;
 453                 msqptr->msg_stime = 0;
 454                 msqptr->msg_rtime = 0;
 455                 msqptr->msg_ctime = time_second;
 456         } else {
 457 #ifdef MSG_DEBUG_OK
 458                 kprintf("didn't find it and wasn't asked to create it\n");
 459 #endif
 460                 return(ENOENT);
 461         }
 462
 463 found:
 464         /* Construct the unique msqid */
 465         uap->sysmsg_result = IXSEQ_TO_IPCID(msqid, msqptr->msg_perm);
 466         return(0);
 467 }
 468
 469 int
 470 sys_msgsnd(struct msgsnd_args *uap)
 471 {
 472         struct proc *p = curproc;
 473         int msqid = uap->msqid;
 474         void *user_msgp = uap->msgp;
 475         size_t msgsz = uap->msgsz;
 476         int msgflg = uap->msgflg;
 477         int segs_needed, eval;
 478         struct msqid_ds *msqptr;
 479         struct msg *msghdr;
 480         short next;
 481
 482 #ifdef MSG_DEBUG_OK
 483         kprintf("call to msgsnd(%d, 0x%x, %d, %d)\n", msqid, user_msgp, msgsz,
 484             msgflg);
 485 #endif
 486
 487         if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL)
 488                 return (ENOSYS);
 489
 490         msqid = IPCID_TO_IX(msqid);
 491
 492         if (msqid < 0 || msqid >= msginfo.msgmni) {
 493 #ifdef MSG_DEBUG_OK
 494                 kprintf("msqid (%d) out of range (0<=msqid<%d)\n", msqid,
 495                     msginfo.msgmni);
 496 #endif
 497                 return(EINVAL);
 498         }
 499
 500         msqptr = &msqids[msqid];
 501         if (msqptr->msg_qbytes == 0) {
 502 #ifdef MSG_DEBUG_OK
 503                 kprintf("no such message queue id\n");
 504 #endif
 505                 return(EINVAL);
 506         }
 507         if (msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) {
 508 #ifdef MSG_DEBUG_OK
 509                 kprintf("wrong sequence number\n");
 510 #endif
 511                 return(EINVAL);
 512         }
 513
 514         if ((eval = ipcperm(p, &msqptr->msg_perm, IPC_W))) {
 515 #ifdef MSG_DEBUG_OK
 516                 kprintf("requester doesn't have write access\n");
 517 #endif
 518                 return(eval);
 519         }
 520
 521         segs_needed = (msgsz + msginfo.msgssz - 1) / msginfo.msgssz;
 522 #ifdef MSG_DEBUG_OK
 523         kprintf("msgsz=%d, msgssz=%d, segs_needed=%d\n", msgsz, msginfo.msgssz,
 524             segs_needed);
 525 #endif
 526         for (;;) {
 527                 int need_more_resources = 0;
 528
 529                 /*
 530                  * check msgsz
 531                  * (inside this loop in case msg_qbytes changes while we sleep)
 532                  */
 533
 534                 if (msgsz > msqptr->msg_qbytes) {
 535 #ifdef MSG_DEBUG_OK
 536                         kprintf("msgsz > msqptr->msg_qbytes\n");
 537 #endif
 538                         return(EINVAL);
 539                 }
 540
 541                 if (msqptr->msg_perm.mode & MSG_LOCKED) {
 542 #ifdef MSG_DEBUG_OK
 543                         kprintf("msqid is locked\n");
 544 #endif
 545                         need_more_resources = 1;
 546                 }
 547                 if (msgsz + msqptr->msg_cbytes > msqptr->msg_qbytes) {
 548 #ifdef MSG_DEBUG_OK
 549                         kprintf("msgsz + msg_cbytes > msg_qbytes\n");
 550 #endif
 551                         need_more_resources = 1;
 552                 }
 553                 if (segs_needed > nfree_msgmaps) {
 554 #ifdef MSG_DEBUG_OK
 555                         kprintf("segs_needed > nfree_msgmaps\n");
 556 #endif
 557                         need_more_resources = 1;
 558                 }
 559                 if (free_msghdrs == NULL) {
 560 #ifdef MSG_DEBUG_OK
 561                         kprintf("no more msghdrs\n");
 562 #endif
 563                         need_more_resources = 1;
 564                 }
 565
 566                 if (need_more_resources) {
 567                         int we_own_it;
 568
 569                         if ((msgflg & IPC_NOWAIT) != 0) {
 570 #ifdef MSG_DEBUG_OK
 571                                 kprintf("need more resources but caller doesn't want to wait\n");
 572 #endif
 573                                 return(EAGAIN);
 574                         }
 575
 576                         if ((msqptr->msg_perm.mode & MSG_LOCKED) != 0) {
 577 #ifdef MSG_DEBUG_OK
 578                                 kprintf("we don't own the msqid_ds\n");
 579 #endif
 580                                 we_own_it = 0;
 581                         } else {
 582                                 /* Force later arrivals to wait for our
 583                                    request */
 584 #ifdef MSG_DEBUG_OK
 585                                 kprintf("we own the msqid_ds\n");
 586 #endif
 587                                 msqptr->msg_perm.mode |= MSG_LOCKED;
 588                                 we_own_it = 1;
 589                         }
 590 #ifdef MSG_DEBUG_OK
 591                         kprintf("goodnight\n");
 592 #endif
 593                         eval = tsleep((caddr_t)msqptr, PCATCH, "msgwait", 0);
 594 #ifdef MSG_DEBUG_OK
 595                         kprintf("good morning, eval=%d\n", eval);
 596 #endif
 597                         if (we_own_it)
 598                                 msqptr->msg_perm.mode &= ~MSG_LOCKED;
 599                         if (eval != 0) {
 600 #ifdef MSG_DEBUG_OK
 601                                 kprintf("msgsnd:  interrupted system call\n");
 602 #endif
 603                                 return(EINTR);
 604                         }
 605
 606                         /*
 607                          * Make sure that the msq queue still exists
 608                          */
 609
 610                         if (msqptr->msg_qbytes == 0) {
 611 #ifdef MSG_DEBUG_OK
 612                                 kprintf("msqid deleted\n");
 613 #endif
 614                                 return(EIDRM);
 615                         }
 616
 617                 } else {
 618 #ifdef MSG_DEBUG_OK
 619                         kprintf("got all the resources that we need\n");
 620 #endif
 621                         break;
 622                 }
 623         }
 624
 625         /*
 626          * We have the resources that we need.
 627          * Make sure!
 628          */
 629
 630         if (msqptr->msg_perm.mode & MSG_LOCKED)
 631                 panic("msg_perm.mode & MSG_LOCKED");
 632         if (segs_needed > nfree_msgmaps)
 633                 panic("segs_needed > nfree_msgmaps");
 634         if (msgsz + msqptr->msg_cbytes > msqptr->msg_qbytes)
 635                 panic("msgsz + msg_cbytes > msg_qbytes");
 636         if (free_msghdrs == NULL)
 637                 panic("no more msghdrs");
 638
 639         /*
 640          * Re-lock the msqid_ds in case we page-fault when copying in the
 641          * message
 642          */
 643
 644         if ((msqptr->msg_perm.mode & MSG_LOCKED) != 0)
 645                 panic("msqid_ds is already locked");
 646         msqptr->msg_perm.mode |= MSG_LOCKED;
 647
 648         /*
 649          * Allocate a message header
 650          */
 651
 652         msghdr = free_msghdrs;
 653         free_msghdrs = msghdr->msg_next;
 654         msghdr->msg_spot = -1;
 655         msghdr->msg_ts = msgsz;
 656
 657         /*
 658          * Allocate space for the message
 659          */
 660
 661         while (segs_needed > 0) {
 662                 if (nfree_msgmaps <= 0)
 663                         panic("not enough msgmaps");
 664                 if (free_msgmaps == -1)
 665                         panic("nil free_msgmaps");
 666                 next = free_msgmaps;
 667                 if (next <= -1)
 668                         panic("next too low #1");
 669                 if (next >= msginfo.msgseg)
 670                         panic("next out of range #1");
 671 #ifdef MSG_DEBUG_OK
 672                 kprintf("allocating segment %d to message\n", next);
 673 #endif
 674                 free_msgmaps = msgmaps[next].next;
 675                 nfree_msgmaps--;
 676                 msgmaps[next].next = msghdr->msg_spot;
 677                 msghdr->msg_spot = next;
 678                 segs_needed--;
 679         }
 680
 681         /*
 682          * Copy in the message type
 683          */
 684
 685         if ((eval = copyin(user_msgp, &msghdr->msg_type,
 686             sizeof(msghdr->msg_type))) != 0) {
 687 #ifdef MSG_DEBUG_OK
 688                 kprintf("error %d copying the message type\n", eval);
 689 #endif
 690                 msg_freehdr(msghdr);
 691                 msqptr->msg_perm.mode &= ~MSG_LOCKED;
 692                 wakeup((caddr_t)msqptr);
 693                 return(eval);
 694         }
 695         user_msgp = (char *)user_msgp + sizeof(msghdr->msg_type);
 696
 697         /*
 698          * Validate the message type
 699          */
 700
 701         if (msghdr->msg_type < 1) {
 702                 msg_freehdr(msghdr);
 703                 msqptr->msg_perm.mode &= ~MSG_LOCKED;
 704                 wakeup((caddr_t)msqptr);
 705 #ifdef MSG_DEBUG_OK
 706                 kprintf("mtype (%d) < 1\n", msghdr->msg_type);
 707 #endif
 708                 return(EINVAL);
 709         }
 710
 711         /*
 712          * Copy in the message body
 713          */
 714
 715         next = msghdr->msg_spot;
 716         while (msgsz > 0) {
 717                 size_t tlen;
 718                 if (msgsz > msginfo.msgssz)
 719                         tlen = msginfo.msgssz;
 720                 else
 721                         tlen = msgsz;
 722                 if (next <= -1)
 723                         panic("next too low #2");
 724                 if (next >= msginfo.msgseg)
 725                         panic("next out of range #2");
 726                 if ((eval = copyin(user_msgp, &msgpool[next * msginfo.msgssz],
 727                     tlen)) != 0) {
 728 #ifdef MSG_DEBUG_OK
 729                         kprintf("error %d copying in message segment\n", eval);
 730 #endif
 731                         msg_freehdr(msghdr);
 732                         msqptr->msg_perm.mode &= ~MSG_LOCKED;
 733                         wakeup((caddr_t)msqptr);
 734                         return(eval);
 735                 }
 736                 msgsz -= tlen;
 737                 user_msgp = (char *)user_msgp + tlen;
 738                 next = msgmaps[next].next;
 739         }
 740         if (next != -1)
 741                 panic("didn't use all the msg segments");
 742
 743         /*
 744          * We've got the message.  Unlock the msqid_ds.
 745          */
 746
 747         msqptr->msg_perm.mode &= ~MSG_LOCKED;
 748
 749         /*
 750          * Make sure that the msqid_ds is still allocated.
 751          */
 752
 753         if (msqptr->msg_qbytes == 0) {
 754                 msg_freehdr(msghdr);
 755                 wakeup((caddr_t)msqptr);
 756                 return(EIDRM);
 757         }
 758
 759         /*
 760          * Put the message into the queue
 761          */
 762
 763         if (msqptr->msg_first == NULL) {
 764                 msqptr->msg_first = msghdr;
 765                 msqptr->msg_last = msghdr;
 766         } else {
 767                 msqptr->msg_last->msg_next = msghdr;
 768                 msqptr->msg_last = msghdr;
 769         }
 770         msqptr->msg_last->msg_next = NULL;
 771
 772         msqptr->msg_cbytes += msghdr->msg_ts;
 773         msqptr->msg_qnum++;
 774         msqptr->msg_lspid = p->p_pid;
 775         msqptr->msg_stime = time_second;
 776
 777         wakeup((caddr_t)msqptr);
 778         uap->sysmsg_result = 0;
 779         return(0);
 780 }
 781
 782 int
 783 sys_msgrcv(struct msgrcv_args *uap)
 784 {
 785         struct proc *p = curproc;
 786         int msqid = uap->msqid;
 787         void *user_msgp = uap->msgp;
 788         size_t msgsz = uap->msgsz;
 789         long msgtyp = uap->msgtyp;
 790         int msgflg = uap->msgflg;
 791         size_t len;
 792         struct msqid_ds *msqptr;
 793         struct msg *msghdr;
 794         int eval;
 795         short next;
 796
 797 #ifdef MSG_DEBUG_OK
 798         kprintf("call to msgrcv(%d, 0x%x, %d, %ld, %d)\n", msqid, user_msgp,
 799             msgsz, msgtyp, msgflg);
 800 #endif
 801
 802         if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL)
 803                 return (ENOSYS);
 804
 805         msqid = IPCID_TO_IX(msqid);
 806
 807         if (msqid < 0 || msqid >= msginfo.msgmni) {
 808 #ifdef MSG_DEBUG_OK
 809                 kprintf("msqid (%d) out of range (0<=msqid<%d)\n", msqid,
 810                     msginfo.msgmni);
 811 #endif
 812                 return(EINVAL);
 813         }
 814
 815         msqptr = &msqids[msqid];
 816         if (msqptr->msg_qbytes == 0) {
 817 #ifdef MSG_DEBUG_OK
 818                 kprintf("no such message queue id\n");
 819 #endif
 820                 return(EINVAL);
 821         }
 822         if (msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) {
 823 #ifdef MSG_DEBUG_OK
 824                 kprintf("wrong sequence number\n");
 825 #endif
 826                 return(EINVAL);
 827         }
 828
 829         if ((eval = ipcperm(p, &msqptr->msg_perm, IPC_R))) {
 830 #ifdef MSG_DEBUG_OK
 831                 kprintf("requester doesn't have read access\n");
 832 #endif
 833                 return(eval);
 834         }
 835
 836         msghdr = NULL;
 837         while (msghdr == NULL) {
 838                 if (msgtyp == 0) {
 839                         msghdr = msqptr->msg_first;
 840                         if (msghdr != NULL) {
 841                                 if (msgsz < msghdr->msg_ts &&
 842                                     (msgflg & MSG_NOERROR) == 0) {
 843 #ifdef MSG_DEBUG_OK
 844                                         kprintf("first message on the queue is too big (want %d, got %d)\n",
 845                                             msgsz, msghdr->msg_ts);
 846 #endif
 847                                         return(E2BIG);
 848                                 }
 849                                 if (msqptr->msg_first == msqptr->msg_last) {
 850                                         msqptr->msg_first = NULL;
 851                                         msqptr->msg_last = NULL;
 852                                 } else {
 853                                         msqptr->msg_first = msghdr->msg_next;
 854                                         if (msqptr->msg_first == NULL)
 855                                                 panic("msg_first/last screwed up #1");
 856                                 }
 857                         }
 858                 } else {
 859                         struct msg *previous;
 860                         struct msg **prev;
 861
 862                         previous = NULL;
 863                         prev = &(msqptr->msg_first);
 864                         while ((msghdr = *prev) != NULL) {
 865                                 /*
 866                                  * Is this message's type an exact match or is
 867                                  * this message's type less than or equal to
 868                                  * the absolute value of a negative msgtyp?
 869                                  * Note that the second half of this test can
 870                                  * NEVER be true if msgtyp is positive since
 871                                  * msg_type is always positive!
 872                                  */
 873
 874                                 if (msgtyp == msghdr->msg_type ||
 875                                     msghdr->msg_type <= -msgtyp) {
 876 #ifdef MSG_DEBUG_OK
 877                                         kprintf("found message type %d, requested %d\n",
 878                                             msghdr->msg_type, msgtyp);
 879 #endif
 880                                         if (msgsz < msghdr->msg_ts &&
 881                                             (msgflg & MSG_NOERROR) == 0) {
 882 #ifdef MSG_DEBUG_OK
 883                                                 kprintf("requested message on the queue is too big (want %d, got %d)\n",
 884                                                     msgsz, msghdr->msg_ts);
 885 #endif
 886                                                 return(E2BIG);
 887                                         }
 888                                         *prev = msghdr->msg_next;
 889                                         if (msghdr == msqptr->msg_last) {
 890                                                 if (previous == NULL) {
 891                                                         if (prev !=
 892                                                             &msqptr->msg_first)
 893                                                                 panic("msg_first/last screwed up #2");
 894                                                         msqptr->msg_first =
 895                                                             NULL;
 896                                                         msqptr->msg_last =
 897                                                             NULL;
 898                                                 } else {
 899                                                         if (prev ==
 900                                                             &msqptr->msg_first)
 901                                                                 panic("msg_first/last screwed up #3");
 902                                                         msqptr->msg_last =
 903                                                             previous;
 904                                                 }
 905                                         }
 906                                         break;
 907                                 }
 908                                 previous = msghdr;
 909                                 prev = &(msghdr->msg_next);
 910                         }
 911                 }
 912
 913                 /*
 914                  * We've either extracted the msghdr for the appropriate
 915                  * message or there isn't one.
 916                  * If there is one then bail out of this loop.
 917                  */
 918
 919                 if (msghdr != NULL)
 920                         break;
 921
 922                 /*
 923                  * Hmph!  No message found.  Does the user want to wait?
 924                  */
 925
 926                 if ((msgflg & IPC_NOWAIT) != 0) {
 927 #ifdef MSG_DEBUG_OK
 928                         kprintf("no appropriate message found (msgtyp=%d)\n",
 929                             msgtyp);
 930 #endif
 931                         /* The SVID says to return ENOMSG. */
 932 #ifdef ENOMSG
 933                         return(ENOMSG);
 934 #else
 935                         /* Unfortunately, BSD doesn't define that code yet! */
 936                         return(EAGAIN);
 937 #endif
 938                 }
 939
 940                 /*
 941                  * Wait for something to happen
 942                  */
 943
 944 #ifdef MSG_DEBUG_OK
 945                 kprintf("msgrcv:  goodnight\n");
 946 #endif
 947                 eval = tsleep((caddr_t)msqptr, PCATCH, "msgwait", 0);
 948 #ifdef MSG_DEBUG_OK
 949                 kprintf("msgrcv:  good morning (eval=%d)\n", eval);
 950 #endif
 951
 952                 if (eval != 0) {
 953 #ifdef MSG_DEBUG_OK
 954                         kprintf("msgsnd:  interrupted system call\n");
 955 #endif
 956                         return(EINTR);
 957                 }
 958
 959                 /*
 960                  * Make sure that the msq queue still exists
 961                  */
 962
 963                 if (msqptr->msg_qbytes == 0 ||
 964                     msqptr->msg_perm.seq != IPCID_TO_SEQ(uap->msqid)) {
 965 #ifdef MSG_DEBUG_OK
 966                         kprintf("msqid deleted\n");
 967 #endif
 968                         return(EIDRM);
 969                 }
 970         }
 971
 972         /*
 973          * Return the message to the user.
 974          *
 975          * First, do the bookkeeping (before we risk being interrupted).
 976          */
 977
 978         msqptr->msg_cbytes -= msghdr->msg_ts;
 979         msqptr->msg_qnum--;
 980         msqptr->msg_lrpid = p->p_pid;
 981         msqptr->msg_rtime = time_second;
 982
 983         /*
 984          * Make msgsz the actual amount that we'll be returning.
 985          * Note that this effectively truncates the message if it is too long
 986          * (since msgsz is never increased).
 987          */
 988
 989 #ifdef MSG_DEBUG_OK
 990         kprintf("found a message, msgsz=%d, msg_ts=%d\n", msgsz,
 991             msghdr->msg_ts);
 992 #endif
 993         if (msgsz > msghdr->msg_ts)
 994                 msgsz = msghdr->msg_ts;
 995
 996         /*
 997          * Return the type to the user.
 998          */
 999
1000         eval = copyout((caddr_t)&(msghdr->msg_type), user_msgp,
1001             sizeof(msghdr->msg_type));
1002         if (eval != 0) {
1003 #ifdef MSG_DEBUG_OK
1004                 kprintf("error (%d) copying out message type\n", eval);
1005 #endif
1006                 msg_freehdr(msghdr);
1007                 wakeup((caddr_t)msqptr);
1008                 return(eval);
1009         }
1010         user_msgp = (char *)user_msgp + sizeof(msghdr->msg_type);
1011
1012         /*
1013          * Return the segments to the user
1014          */
1015
1016         next = msghdr->msg_spot;
1017         for (len = 0; len < msgsz; len += msginfo.msgssz) {
1018                 size_t tlen;
1019
1020                 if (msgsz - len > msginfo.msgssz)
1021                         tlen = msginfo.msgssz;
1022                 else
1023                         tlen = msgsz - len;
1024                 if (next <= -1)
1025                         panic("next too low #3");
1026                 if (next >= msginfo.msgseg)
1027                         panic("next out of range #3");
1028                 eval = copyout((caddr_t)&msgpool[next * msginfo.msgssz],
1029                     user_msgp, tlen);
1030                 if (eval != 0) {
1031 #ifdef MSG_DEBUG_OK
1032                         kprintf("error (%d) copying out message segment\n",
1033                             eval);
1034 #endif
1035                         msg_freehdr(msghdr);
1036                         wakeup((caddr_t)msqptr);
1037                         return(eval);
1038                 }
1039                 user_msgp = (char *)user_msgp + tlen;
1040                 next = msgmaps[next].next;
1041         }
1042
1043         /*
1044          * Done, return the actual number of bytes copied out.
1045          */
1046
1047         msg_freehdr(msghdr);
1048         wakeup((caddr_t)msqptr);
1049         uap->sysmsg_result = msgsz;
1050         return(0);
1051 }
1052
1053 static int
1054 sysctl_msqids(SYSCTL_HANDLER_ARGS)
1055 {
1056
1057         return (SYSCTL_OUT(req, msqids,
1058             sizeof(struct msqid_ds) * msginfo.msgmni));
1059 }
1060
1061 TUNABLE_INT("kern.ipc.msgseg", &msginfo.msgseg);
1062 TUNABLE_INT("kern.ipc.msgssz", &msginfo.msgssz);
1063 TUNABLE_INT("kern.ipc.msgmni", &msginfo.msgmni);
1064
1065 SYSCTL_INT(_kern_ipc, OID_AUTO, msgmax, CTLFLAG_RD, &msginfo.msgmax, 0, "");
1066 SYSCTL_INT(_kern_ipc, OID_AUTO, msgmni, CTLFLAG_RD, &msginfo.msgmni, 0, "");
1067 SYSCTL_INT(_kern_ipc, OID_AUTO, msgmnb, CTLFLAG_RD, &msginfo.msgmnb, 0, "");
1068 SYSCTL_INT(_kern_ipc, OID_AUTO, msgtql, CTLFLAG_RD, &msginfo.msgtql, 0, "");
1069 SYSCTL_INT(_kern_ipc, OID_AUTO, msgssz, CTLFLAG_RD, &msginfo.msgssz, 0, "");
1070 SYSCTL_INT(_kern_ipc, OID_AUTO, msgseg, CTLFLAG_RD, &msginfo.msgseg, 0, "");
1071 SYSCTL_PROC(_kern_ipc, OID_AUTO, msqids, CTLFLAG_RD,
1072     NULL, 0, sysctl_msqids, "", "Message queue IDs");