The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_sem.c

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    1 /*-
    2  * Copyright (c) 2002 Alfred Perlstein <alfred@FreeBSD.org>
    3  * Copyright (c) 2003-2005 SPARTA, Inc.
    4  * Copyright (c) 2005 Robert N. M. Watson
    5  * All rights reserved.
    6  *
    7  * This software was developed for the FreeBSD Project in part by Network
    8  * Associates Laboratories, the Security Research Division of Network
    9  * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"),
   10  * as part of the DARPA CHATS research program.
   11  *
   12  * Redistribution and use in source and binary forms, with or without
   13  * modification, are permitted provided that the following conditions
   14  * are met:
   15  * 1. Redistributions of source code must retain the above copyright
   16  *    notice, this list of conditions and the following disclaimer.
   17  * 2. Redistributions in binary form must reproduce the above copyright
   18  *    notice, this list of conditions and the following disclaimer in the
   19  *    documentation and/or other materials provided with the distribution.
   20  *
   21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   31  * SUCH DAMAGE.
   32  */
   33 
   34 #include <sys/cdefs.h>
   35 __FBSDID("$FreeBSD: releng/9.1/sys/kern/uipc_sem.c 225617 2011-09-16 13:58:51Z kmacy $");
   36 
   37 #include "opt_compat.h"
   38 #include "opt_posix.h"
   39 
   40 #include <sys/param.h>
   41 #include <sys/capability.h>
   42 #include <sys/condvar.h>
   43 #include <sys/fcntl.h>
   44 #include <sys/file.h>
   45 #include <sys/filedesc.h>
   46 #include <sys/fnv_hash.h>
   47 #include <sys/kernel.h>
   48 #include <sys/ksem.h>
   49 #include <sys/lock.h>
   50 #include <sys/malloc.h>
   51 #include <sys/module.h>
   52 #include <sys/mutex.h>
   53 #include <sys/priv.h>
   54 #include <sys/proc.h>
   55 #include <sys/posix4.h>
   56 #include <sys/_semaphore.h>
   57 #include <sys/stat.h>
   58 #include <sys/syscall.h>
   59 #include <sys/syscallsubr.h>
   60 #include <sys/sysctl.h>
   61 #include <sys/sysent.h>
   62 #include <sys/sysproto.h>
   63 #include <sys/systm.h>
   64 #include <sys/sx.h>
   65 #include <sys/vnode.h>
   66 
   67 #include <security/mac/mac_framework.h>
   68 
   69 FEATURE(p1003_1b_semaphores, "POSIX P1003.1B semaphores support");
   70 /*
   71  * TODO
   72  *
   73  * - Resource limits?
   74  * - Update fstat(1)
   75  * - Replace global sem_lock with mtx_pool locks?
   76  * - Add a MAC check_create() hook for creating new named semaphores.
   77  */
   78 
   79 #ifndef SEM_MAX
   80 #define SEM_MAX 30
   81 #endif
   82 
   83 #ifdef SEM_DEBUG
   84 #define DP(x)   printf x
   85 #else
   86 #define DP(x)
   87 #endif
   88 
   89 struct ksem_mapping {
   90         char            *km_path;
   91         Fnv32_t         km_fnv;
   92         struct ksem     *km_ksem;
   93         LIST_ENTRY(ksem_mapping) km_link;
   94 };
   95 
   96 static MALLOC_DEFINE(M_KSEM, "ksem", "semaphore file descriptor");
   97 static LIST_HEAD(, ksem_mapping) *ksem_dictionary;
   98 static struct sx ksem_dict_lock;
   99 static struct mtx ksem_count_lock;
  100 static struct mtx sem_lock;
  101 static u_long ksem_hash;
  102 static int ksem_dead;
  103 
  104 #define KSEM_HASH(fnv)  (&ksem_dictionary[(fnv) & ksem_hash])
  105 
  106 static int nsems = 0;
  107 SYSCTL_DECL(_p1003_1b);
  108 SYSCTL_INT(_p1003_1b, OID_AUTO, nsems, CTLFLAG_RD, &nsems, 0,
  109     "Number of active kernel POSIX semaphores");
  110 
  111 static int      kern_sem_wait(struct thread *td, semid_t id, int tryflag,
  112                     struct timespec *abstime);
  113 static int      ksem_access(struct ksem *ks, struct ucred *ucred);
  114 static struct ksem *ksem_alloc(struct ucred *ucred, mode_t mode,
  115                     unsigned int value);
  116 static int      ksem_create(struct thread *td, const char *path,
  117                     semid_t *semidp, mode_t mode, unsigned int value,
  118                     int flags, int compat32);
  119 static void     ksem_drop(struct ksem *ks);
  120 static int      ksem_get(struct thread *td, semid_t id, cap_rights_t rights,
  121     struct file **fpp);
  122 static struct ksem *ksem_hold(struct ksem *ks);
  123 static void     ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks);
  124 static struct ksem *ksem_lookup(char *path, Fnv32_t fnv);
  125 static void     ksem_module_destroy(void);
  126 static int      ksem_module_init(void);
  127 static int      ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
  128 static int      sem_modload(struct module *module, int cmd, void *arg);
  129 
  130 static fo_rdwr_t        ksem_read;
  131 static fo_rdwr_t        ksem_write;
  132 static fo_truncate_t    ksem_truncate;
  133 static fo_ioctl_t       ksem_ioctl;
  134 static fo_poll_t        ksem_poll;
  135 static fo_kqfilter_t    ksem_kqfilter;
  136 static fo_stat_t        ksem_stat;
  137 static fo_close_t       ksem_closef;
  138 static fo_chmod_t       ksem_chmod;
  139 static fo_chown_t       ksem_chown;
  140 
  141 /* File descriptor operations. */
  142 static struct fileops ksem_ops = {
  143         .fo_read = ksem_read,
  144         .fo_write = ksem_write,
  145         .fo_truncate = ksem_truncate,
  146         .fo_ioctl = ksem_ioctl,
  147         .fo_poll = ksem_poll,
  148         .fo_kqfilter = ksem_kqfilter,
  149         .fo_stat = ksem_stat,
  150         .fo_close = ksem_closef,
  151         .fo_chmod = ksem_chmod,
  152         .fo_chown = ksem_chown,
  153         .fo_flags = DFLAG_PASSABLE
  154 };
  155 
  156 FEATURE(posix_sem, "POSIX semaphores");
  157 
  158 static int
  159 ksem_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
  160     int flags, struct thread *td)
  161 {
  162 
  163         return (EOPNOTSUPP);
  164 }
  165 
  166 static int
  167 ksem_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
  168     int flags, struct thread *td)
  169 {
  170 
  171         return (EOPNOTSUPP);
  172 }
  173 
  174 static int
  175 ksem_truncate(struct file *fp, off_t length, struct ucred *active_cred,
  176     struct thread *td)
  177 {
  178 
  179         return (EINVAL);
  180 }
  181 
  182 static int
  183 ksem_ioctl(struct file *fp, u_long com, void *data,
  184     struct ucred *active_cred, struct thread *td)
  185 {
  186 
  187         return (EOPNOTSUPP);
  188 }
  189 
  190 static int
  191 ksem_poll(struct file *fp, int events, struct ucred *active_cred,
  192     struct thread *td)
  193 {
  194 
  195         return (EOPNOTSUPP);
  196 }
  197 
  198 static int
  199 ksem_kqfilter(struct file *fp, struct knote *kn)
  200 {
  201 
  202         return (EOPNOTSUPP);
  203 }
  204 
  205 static int
  206 ksem_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
  207     struct thread *td)
  208 {
  209         struct ksem *ks;
  210 #ifdef MAC
  211         int error;
  212 #endif
  213 
  214         ks = fp->f_data;
  215 
  216 #ifdef MAC
  217         error = mac_posixsem_check_stat(active_cred, fp->f_cred, ks);
  218         if (error)
  219                 return (error);
  220 #endif
  221         
  222         /*
  223          * Attempt to return sanish values for fstat() on a semaphore
  224          * file descriptor.
  225          */
  226         bzero(sb, sizeof(*sb));
  227 
  228         mtx_lock(&sem_lock);
  229         sb->st_atim = ks->ks_atime;
  230         sb->st_ctim = ks->ks_ctime;
  231         sb->st_mtim = ks->ks_mtime;
  232         sb->st_birthtim = ks->ks_birthtime;
  233         sb->st_uid = ks->ks_uid;
  234         sb->st_gid = ks->ks_gid;
  235         sb->st_mode = S_IFREG | ks->ks_mode;            /* XXX */
  236         mtx_unlock(&sem_lock);
  237 
  238         return (0);
  239 }
  240 
  241 static int
  242 ksem_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
  243     struct thread *td)
  244 {
  245         struct ksem *ks;
  246         int error;
  247 
  248         error = 0;
  249         ks = fp->f_data;
  250         mtx_lock(&sem_lock);
  251 #ifdef MAC
  252         error = mac_posixsem_check_setmode(active_cred, ks, mode);
  253         if (error != 0)
  254                 goto out;
  255 #endif
  256         error = vaccess(VREG, ks->ks_mode, ks->ks_uid, ks->ks_gid, VADMIN,
  257             active_cred, NULL);
  258         if (error != 0)
  259                 goto out;
  260         ks->ks_mode = mode & ACCESSPERMS;
  261 out:
  262         mtx_unlock(&sem_lock);
  263         return (error);
  264 }
  265 
  266 static int
  267 ksem_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
  268     struct thread *td)
  269 {
  270         struct ksem *ks;
  271         int error;
  272 
  273         error = 0;
  274         ks = fp->f_data;
  275         mtx_lock(&sem_lock);
  276 #ifdef MAC
  277         error = mac_posixsem_check_setowner(active_cred, ks, uid, gid);
  278         if (error != 0)
  279                 goto out;
  280 #endif
  281         if (uid == (uid_t)-1)
  282                 uid = ks->ks_uid;
  283         if (gid == (gid_t)-1)
  284                  gid = ks->ks_gid;
  285         if (((uid != ks->ks_uid && uid != active_cred->cr_uid) ||
  286             (gid != ks->ks_gid && !groupmember(gid, active_cred))) &&
  287             (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN, 0)))
  288                 goto out;
  289         ks->ks_uid = uid;
  290         ks->ks_gid = gid;
  291 out:
  292         mtx_unlock(&sem_lock);
  293         return (error);
  294 }
  295 
  296 static int
  297 ksem_closef(struct file *fp, struct thread *td)
  298 {
  299         struct ksem *ks;
  300 
  301         ks = fp->f_data;
  302         fp->f_data = NULL;
  303         ksem_drop(ks);
  304 
  305         return (0);
  306 }
  307 
  308 /*
  309  * ksem object management including creation and reference counting
  310  * routines.
  311  */
  312 static struct ksem *
  313 ksem_alloc(struct ucred *ucred, mode_t mode, unsigned int value)
  314 {
  315         struct ksem *ks;
  316 
  317         mtx_lock(&ksem_count_lock);
  318         if (nsems == p31b_getcfg(CTL_P1003_1B_SEM_NSEMS_MAX) || ksem_dead) {
  319                 mtx_unlock(&ksem_count_lock);
  320                 return (NULL);
  321         }
  322         nsems++;
  323         mtx_unlock(&ksem_count_lock);
  324         ks = malloc(sizeof(*ks), M_KSEM, M_WAITOK | M_ZERO);
  325         ks->ks_uid = ucred->cr_uid;
  326         ks->ks_gid = ucred->cr_gid;
  327         ks->ks_mode = mode;
  328         ks->ks_value = value;
  329         cv_init(&ks->ks_cv, "ksem");
  330         vfs_timestamp(&ks->ks_birthtime);
  331         ks->ks_atime = ks->ks_mtime = ks->ks_ctime = ks->ks_birthtime;
  332         refcount_init(&ks->ks_ref, 1);
  333 #ifdef MAC
  334         mac_posixsem_init(ks);
  335         mac_posixsem_create(ucred, ks);
  336 #endif
  337 
  338         return (ks);
  339 }
  340 
  341 static struct ksem *
  342 ksem_hold(struct ksem *ks)
  343 {
  344 
  345         refcount_acquire(&ks->ks_ref);
  346         return (ks);
  347 }
  348 
  349 static void
  350 ksem_drop(struct ksem *ks)
  351 {
  352 
  353         if (refcount_release(&ks->ks_ref)) {
  354 #ifdef MAC
  355                 mac_posixsem_destroy(ks);
  356 #endif
  357                 cv_destroy(&ks->ks_cv);
  358                 free(ks, M_KSEM);
  359                 mtx_lock(&ksem_count_lock);
  360                 nsems--;
  361                 mtx_unlock(&ksem_count_lock);
  362         }
  363 }
  364 
  365 /*
  366  * Determine if the credentials have sufficient permissions for read
  367  * and write access.
  368  */
  369 static int
  370 ksem_access(struct ksem *ks, struct ucred *ucred)
  371 {
  372         int error;
  373 
  374         error = vaccess(VREG, ks->ks_mode, ks->ks_uid, ks->ks_gid,
  375             VREAD | VWRITE, ucred, NULL);
  376         if (error)
  377                 error = priv_check_cred(ucred, PRIV_SEM_WRITE, 0);
  378         return (error);
  379 }
  380 
  381 /*
  382  * Dictionary management.  We maintain an in-kernel dictionary to map
  383  * paths to semaphore objects.  We use the FNV hash on the path to
  384  * store the mappings in a hash table.
  385  */
  386 static struct ksem *
  387 ksem_lookup(char *path, Fnv32_t fnv)
  388 {
  389         struct ksem_mapping *map;
  390 
  391         LIST_FOREACH(map, KSEM_HASH(fnv), km_link) {
  392                 if (map->km_fnv != fnv)
  393                         continue;
  394                 if (strcmp(map->km_path, path) == 0)
  395                         return (map->km_ksem);
  396         }
  397 
  398         return (NULL);
  399 }
  400 
  401 static void
  402 ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks)
  403 {
  404         struct ksem_mapping *map;
  405 
  406         map = malloc(sizeof(struct ksem_mapping), M_KSEM, M_WAITOK);
  407         map->km_path = path;
  408         map->km_fnv = fnv;
  409         map->km_ksem = ksem_hold(ks);
  410         LIST_INSERT_HEAD(KSEM_HASH(fnv), map, km_link);
  411 }
  412 
  413 static int
  414 ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
  415 {
  416         struct ksem_mapping *map;
  417         int error;
  418 
  419         LIST_FOREACH(map, KSEM_HASH(fnv), km_link) {
  420                 if (map->km_fnv != fnv)
  421                         continue;
  422                 if (strcmp(map->km_path, path) == 0) {
  423 #ifdef MAC
  424                         error = mac_posixsem_check_unlink(ucred, map->km_ksem);
  425                         if (error)
  426                                 return (error);
  427 #endif
  428                         error = ksem_access(map->km_ksem, ucred);
  429                         if (error)
  430                                 return (error);
  431                         LIST_REMOVE(map, km_link);
  432                         ksem_drop(map->km_ksem);
  433                         free(map->km_path, M_KSEM);
  434                         free(map, M_KSEM);
  435                         return (0);
  436                 }
  437         }
  438 
  439         return (ENOENT);
  440 }
  441 
  442 static int
  443 ksem_create_copyout_semid(struct thread *td, semid_t *semidp, int fd,
  444     int compat32)
  445 {
  446         semid_t semid;
  447 #ifdef COMPAT_FREEBSD32
  448         int32_t semid32;
  449 #endif
  450         void *ptr;
  451         size_t ptrs;
  452 
  453 #ifdef COMPAT_FREEBSD32
  454         if (compat32) {
  455                 semid32 = fd;
  456                 ptr = &semid32;
  457                 ptrs = sizeof(semid32);
  458         } else {
  459 #endif
  460                 semid = fd;
  461                 ptr = &semid;
  462                 ptrs = sizeof(semid);
  463                 compat32 = 0; /* silence gcc */
  464 #ifdef COMPAT_FREEBSD32
  465         }
  466 #endif
  467 
  468         return (copyout(ptr, semidp, ptrs));
  469 }
  470 
  471 /* Other helper routines. */
  472 static int
  473 ksem_create(struct thread *td, const char *name, semid_t *semidp, mode_t mode,
  474     unsigned int value, int flags, int compat32)
  475 {
  476         struct filedesc *fdp;
  477         struct ksem *ks;
  478         struct file *fp;
  479         char *path;
  480         Fnv32_t fnv;
  481         int error, fd;
  482 
  483         if (value > SEM_VALUE_MAX)
  484                 return (EINVAL);
  485 
  486         fdp = td->td_proc->p_fd;
  487         mode = (mode & ~fdp->fd_cmask) & ACCESSPERMS;
  488         error = falloc(td, &fp, &fd, 0);
  489         if (error) {
  490                 if (name == NULL)
  491                         error = ENOSPC;
  492                 return (error);
  493         }
  494 
  495         /*
  496          * Go ahead and copyout the file descriptor now.  This is a bit
  497          * premature, but it is a lot easier to handle errors as opposed
  498          * to later when we've possibly created a new semaphore, etc.
  499          */
  500         error = ksem_create_copyout_semid(td, semidp, fd, compat32);
  501         if (error) {
  502                 fdclose(fdp, fp, fd, td);
  503                 fdrop(fp, td);
  504                 return (error);
  505         }
  506 
  507         if (name == NULL) {
  508                 /* Create an anonymous semaphore. */
  509                 ks = ksem_alloc(td->td_ucred, mode, value);
  510                 if (ks == NULL)
  511                         error = ENOSPC;
  512                 else
  513                         ks->ks_flags |= KS_ANONYMOUS;
  514         } else {
  515                 path = malloc(MAXPATHLEN, M_KSEM, M_WAITOK);
  516                 error = copyinstr(name, path, MAXPATHLEN, NULL);
  517 
  518                 /* Require paths to start with a '/' character. */
  519                 if (error == 0 && path[0] != '/')
  520                         error = EINVAL;
  521                 if (error) {
  522                         fdclose(fdp, fp, fd, td);
  523                         fdrop(fp, td);
  524                         free(path, M_KSEM);
  525                         return (error);
  526                 }
  527 
  528                 fnv = fnv_32_str(path, FNV1_32_INIT);
  529                 sx_xlock(&ksem_dict_lock);
  530                 ks = ksem_lookup(path, fnv);
  531                 if (ks == NULL) {
  532                         /* Object does not exist, create it if requested. */
  533                         if (flags & O_CREAT) {
  534                                 ks = ksem_alloc(td->td_ucred, mode, value);
  535                                 if (ks == NULL)
  536                                         error = ENFILE;
  537                                 else {
  538                                         ksem_insert(path, fnv, ks);
  539                                         path = NULL;
  540                                 }
  541                         } else
  542                                 error = ENOENT;
  543                 } else {
  544                         /*
  545                          * Object already exists, obtain a new
  546                          * reference if requested and permitted.
  547                          */
  548                         if ((flags & (O_CREAT | O_EXCL)) ==
  549                             (O_CREAT | O_EXCL))
  550                                 error = EEXIST;
  551                         else {
  552 #ifdef MAC
  553                                 error = mac_posixsem_check_open(td->td_ucred,
  554                                     ks);
  555                                 if (error == 0)
  556 #endif
  557                                 error = ksem_access(ks, td->td_ucred);
  558                         }
  559                         if (error == 0)
  560                                 ksem_hold(ks);
  561 #ifdef INVARIANTS
  562                         else
  563                                 ks = NULL;
  564 #endif
  565                 }
  566                 sx_xunlock(&ksem_dict_lock);
  567                 if (path)
  568                         free(path, M_KSEM);
  569         }
  570 
  571         if (error) {
  572                 KASSERT(ks == NULL, ("ksem_create error with a ksem"));
  573                 fdclose(fdp, fp, fd, td);
  574                 fdrop(fp, td);
  575                 return (error);
  576         }
  577         KASSERT(ks != NULL, ("ksem_create w/o a ksem"));
  578 
  579         finit(fp, FREAD | FWRITE, DTYPE_SEM, ks, &ksem_ops);
  580 
  581         FILEDESC_XLOCK(fdp);
  582         if (fdp->fd_ofiles[fd] == fp)
  583                 fdp->fd_ofileflags[fd] |= UF_EXCLOSE;
  584         FILEDESC_XUNLOCK(fdp);
  585         fdrop(fp, td);
  586 
  587         return (0);
  588 }
  589 
  590 static int
  591 ksem_get(struct thread *td, semid_t id, cap_rights_t rights, struct file **fpp)
  592 {
  593         struct ksem *ks;
  594         struct file *fp;
  595         int error;
  596 
  597         error = fget(td, id, rights, &fp);
  598         if (error)
  599                 return (EINVAL);
  600         if (fp->f_type != DTYPE_SEM) {
  601                 fdrop(fp, td);
  602                 return (EINVAL);
  603         }
  604         ks = fp->f_data;
  605         if (ks->ks_flags & KS_DEAD) {
  606                 fdrop(fp, td);
  607                 return (EINVAL);
  608         }
  609         *fpp = fp;
  610         return (0);
  611 }
  612 
  613 /* System calls. */
  614 #ifndef _SYS_SYSPROTO_H_
  615 struct ksem_init_args {
  616         unsigned int    value;
  617         semid_t         *idp;
  618 };
  619 #endif
  620 int
  621 sys_ksem_init(struct thread *td, struct ksem_init_args *uap)
  622 {
  623 
  624         return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value,
  625             0, 0));
  626 }
  627 
  628 #ifndef _SYS_SYSPROTO_H_
  629 struct ksem_open_args {
  630         char            *name;
  631         int             oflag;
  632         mode_t          mode;
  633         unsigned int    value;
  634         semid_t         *idp;   
  635 };
  636 #endif
  637 int
  638 sys_ksem_open(struct thread *td, struct ksem_open_args *uap)
  639 {
  640 
  641         DP((">>> ksem_open start, pid=%d\n", (int)td->td_proc->p_pid));
  642 
  643         if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0)
  644                 return (EINVAL);
  645         return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value,
  646             uap->oflag, 0));
  647 }
  648 
  649 #ifndef _SYS_SYSPROTO_H_
  650 struct ksem_unlink_args {
  651         char            *name;
  652 };
  653 #endif
  654 int
  655 sys_ksem_unlink(struct thread *td, struct ksem_unlink_args *uap)
  656 {
  657         char *path;
  658         Fnv32_t fnv;
  659         int error;
  660 
  661         path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
  662         error = copyinstr(uap->name, path, MAXPATHLEN, NULL);
  663         if (error) {
  664                 free(path, M_TEMP);
  665                 return (error);
  666         }
  667 
  668         fnv = fnv_32_str(path, FNV1_32_INIT);
  669         sx_xlock(&ksem_dict_lock);
  670         error = ksem_remove(path, fnv, td->td_ucred);
  671         sx_xunlock(&ksem_dict_lock);
  672         free(path, M_TEMP);
  673 
  674         return (error);
  675 }
  676 
  677 #ifndef _SYS_SYSPROTO_H_
  678 struct ksem_close_args {
  679         semid_t         id;
  680 };
  681 #endif
  682 int
  683 sys_ksem_close(struct thread *td, struct ksem_close_args *uap)
  684 {
  685         struct ksem *ks;
  686         struct file *fp;
  687         int error;
  688 
  689         /* No capability rights required to close a semaphore. */
  690         error = ksem_get(td, uap->id, 0, &fp);
  691         if (error)
  692                 return (error);
  693         ks = fp->f_data;
  694         if (ks->ks_flags & KS_ANONYMOUS) {
  695                 fdrop(fp, td);
  696                 return (EINVAL);
  697         }
  698         error = kern_close(td, uap->id);
  699         fdrop(fp, td);
  700         return (error);
  701 }
  702 
  703 #ifndef _SYS_SYSPROTO_H_
  704 struct ksem_post_args {
  705         semid_t id;
  706 };
  707 #endif
  708 int
  709 sys_ksem_post(struct thread *td, struct ksem_post_args *uap)
  710 {
  711         struct file *fp;
  712         struct ksem *ks;
  713         int error;
  714 
  715         error = ksem_get(td, uap->id, CAP_SEM_POST, &fp);
  716         if (error)
  717                 return (error);
  718         ks = fp->f_data;
  719 
  720         mtx_lock(&sem_lock);
  721 #ifdef MAC
  722         error = mac_posixsem_check_post(td->td_ucred, fp->f_cred, ks);
  723         if (error)
  724                 goto err;
  725 #endif
  726         if (ks->ks_value == SEM_VALUE_MAX) {
  727                 error = EOVERFLOW;
  728                 goto err;
  729         }
  730         ++ks->ks_value;
  731         if (ks->ks_waiters > 0)
  732                 cv_signal(&ks->ks_cv);
  733         error = 0;
  734         vfs_timestamp(&ks->ks_ctime);
  735 err:
  736         mtx_unlock(&sem_lock);
  737         fdrop(fp, td);
  738         return (error);
  739 }
  740 
  741 #ifndef _SYS_SYSPROTO_H_
  742 struct ksem_wait_args {
  743         semid_t         id;
  744 };
  745 #endif
  746 int
  747 sys_ksem_wait(struct thread *td, struct ksem_wait_args *uap)
  748 {
  749 
  750         return (kern_sem_wait(td, uap->id, 0, NULL));
  751 }
  752 
  753 #ifndef _SYS_SYSPROTO_H_
  754 struct ksem_timedwait_args {
  755         semid_t         id;
  756         const struct timespec *abstime;
  757 };
  758 #endif
  759 int
  760 sys_ksem_timedwait(struct thread *td, struct ksem_timedwait_args *uap)
  761 {
  762         struct timespec abstime;
  763         struct timespec *ts;
  764         int error;
  765 
  766         /*
  767          * We allow a null timespec (wait forever).
  768          */
  769         if (uap->abstime == NULL)
  770                 ts = NULL;
  771         else {
  772                 error = copyin(uap->abstime, &abstime, sizeof(abstime));
  773                 if (error != 0)
  774                         return (error);
  775                 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0)
  776                         return (EINVAL);
  777                 ts = &abstime;
  778         }
  779         return (kern_sem_wait(td, uap->id, 0, ts));
  780 }
  781 
  782 #ifndef _SYS_SYSPROTO_H_
  783 struct ksem_trywait_args {
  784         semid_t         id;
  785 };
  786 #endif
  787 int
  788 sys_ksem_trywait(struct thread *td, struct ksem_trywait_args *uap)
  789 {
  790 
  791         return (kern_sem_wait(td, uap->id, 1, NULL));
  792 }
  793 
  794 static int
  795 kern_sem_wait(struct thread *td, semid_t id, int tryflag,
  796     struct timespec *abstime)
  797 {
  798         struct timespec ts1, ts2;
  799         struct timeval tv;
  800         struct file *fp;
  801         struct ksem *ks;
  802         int error;
  803 
  804         DP((">>> kern_sem_wait entered! pid=%d\n", (int)td->td_proc->p_pid));
  805         error = ksem_get(td, id, CAP_SEM_WAIT, &fp);
  806         if (error)
  807                 return (error);
  808         ks = fp->f_data;
  809         mtx_lock(&sem_lock);
  810         DP((">>> kern_sem_wait critical section entered! pid=%d\n",
  811             (int)td->td_proc->p_pid));
  812 #ifdef MAC
  813         error = mac_posixsem_check_wait(td->td_ucred, fp->f_cred, ks);
  814         if (error) {
  815                 DP(("kern_sem_wait mac failed\n"));
  816                 goto err;
  817         }
  818 #endif
  819         DP(("kern_sem_wait value = %d, tryflag %d\n", ks->ks_value, tryflag));
  820         vfs_timestamp(&ks->ks_atime);
  821         while (ks->ks_value == 0) {
  822                 ks->ks_waiters++;
  823                 if (tryflag != 0)
  824                         error = EAGAIN;
  825                 else if (abstime == NULL)
  826                         error = cv_wait_sig(&ks->ks_cv, &sem_lock);
  827                 else {
  828                         for (;;) {
  829                                 ts1 = *abstime;
  830                                 getnanotime(&ts2);
  831                                 timespecsub(&ts1, &ts2);
  832                                 TIMESPEC_TO_TIMEVAL(&tv, &ts1);
  833                                 if (tv.tv_sec < 0) {
  834                                         error = ETIMEDOUT;
  835                                         break;
  836                                 }
  837                                 error = cv_timedwait_sig(&ks->ks_cv,
  838                                     &sem_lock, tvtohz(&tv));
  839                                 if (error != EWOULDBLOCK)
  840                                         break;
  841                         }
  842                 }
  843                 ks->ks_waiters--;
  844                 if (error)
  845                         goto err;
  846         }
  847         ks->ks_value--;
  848         DP(("kern_sem_wait value post-decrement = %d\n", ks->ks_value));
  849         error = 0;
  850 err:
  851         mtx_unlock(&sem_lock);
  852         fdrop(fp, td);
  853         DP(("<<< kern_sem_wait leaving, pid=%d, error = %d\n",
  854             (int)td->td_proc->p_pid, error));
  855         return (error);
  856 }
  857 
  858 #ifndef _SYS_SYSPROTO_H_
  859 struct ksem_getvalue_args {
  860         semid_t         id;
  861         int             *val;
  862 };
  863 #endif
  864 int
  865 sys_ksem_getvalue(struct thread *td, struct ksem_getvalue_args *uap)
  866 {
  867         struct file *fp;
  868         struct ksem *ks;
  869         int error, val;
  870 
  871         error = ksem_get(td, uap->id, CAP_SEM_GETVALUE, &fp);
  872         if (error)
  873                 return (error);
  874         ks = fp->f_data;
  875 
  876         mtx_lock(&sem_lock);
  877 #ifdef MAC
  878         error = mac_posixsem_check_getvalue(td->td_ucred, fp->f_cred, ks);
  879         if (error) {
  880                 mtx_unlock(&sem_lock);
  881                 fdrop(fp, td);
  882                 return (error);
  883         }
  884 #endif
  885         val = ks->ks_value;
  886         vfs_timestamp(&ks->ks_atime);
  887         mtx_unlock(&sem_lock);
  888         fdrop(fp, td);
  889         error = copyout(&val, uap->val, sizeof(val));
  890         return (error);
  891 }
  892 
  893 #ifndef _SYS_SYSPROTO_H_
  894 struct ksem_destroy_args {
  895         semid_t         id;
  896 };
  897 #endif
  898 int
  899 sys_ksem_destroy(struct thread *td, struct ksem_destroy_args *uap)
  900 {
  901         struct file *fp;
  902         struct ksem *ks;
  903         int error;
  904 
  905         /* No capability rights required to close a semaphore. */
  906         error = ksem_get(td, uap->id, 0, &fp);
  907         if (error)
  908                 return (error);
  909         ks = fp->f_data;
  910         if (!(ks->ks_flags & KS_ANONYMOUS)) {
  911                 fdrop(fp, td);
  912                 return (EINVAL);
  913         }
  914         mtx_lock(&sem_lock);
  915         if (ks->ks_waiters != 0) {
  916                 mtx_unlock(&sem_lock);
  917                 error = EBUSY;
  918                 goto err;
  919         }
  920         ks->ks_flags |= KS_DEAD;
  921         mtx_unlock(&sem_lock);
  922 
  923         error = kern_close(td, uap->id);
  924 err:
  925         fdrop(fp, td);
  926         return (error);
  927 }
  928 
  929 static struct syscall_helper_data ksem_syscalls[] = {
  930         SYSCALL_INIT_HELPER(ksem_init),
  931         SYSCALL_INIT_HELPER(ksem_open),
  932         SYSCALL_INIT_HELPER(ksem_unlink),
  933         SYSCALL_INIT_HELPER(ksem_close),
  934         SYSCALL_INIT_HELPER(ksem_post),
  935         SYSCALL_INIT_HELPER(ksem_wait),
  936         SYSCALL_INIT_HELPER(ksem_timedwait),
  937         SYSCALL_INIT_HELPER(ksem_trywait),
  938         SYSCALL_INIT_HELPER(ksem_getvalue),
  939         SYSCALL_INIT_HELPER(ksem_destroy),
  940         SYSCALL_INIT_LAST
  941 };
  942 
  943 #ifdef COMPAT_FREEBSD32
  944 #include <compat/freebsd32/freebsd32.h>
  945 #include <compat/freebsd32/freebsd32_proto.h>
  946 #include <compat/freebsd32/freebsd32_signal.h>
  947 #include <compat/freebsd32/freebsd32_syscall.h>
  948 #include <compat/freebsd32/freebsd32_util.h>
  949 
  950 int
  951 freebsd32_ksem_init(struct thread *td, struct freebsd32_ksem_init_args *uap)
  952 {
  953 
  954         return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value,
  955             0, 1));
  956 }
  957 
  958 int
  959 freebsd32_ksem_open(struct thread *td, struct freebsd32_ksem_open_args *uap)
  960 {
  961 
  962         if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0)
  963                 return (EINVAL);
  964         return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value,
  965             uap->oflag, 1));
  966 }
  967 
  968 int
  969 freebsd32_ksem_timedwait(struct thread *td,
  970     struct freebsd32_ksem_timedwait_args *uap)
  971 {
  972         struct timespec32 abstime32;
  973         struct timespec *ts, abstime;
  974         int error;
  975 
  976         /*
  977          * We allow a null timespec (wait forever).
  978          */
  979         if (uap->abstime == NULL)
  980                 ts = NULL;
  981         else {
  982                 error = copyin(uap->abstime, &abstime32, sizeof(abstime32));
  983                 if (error != 0)
  984                         return (error);
  985                 CP(abstime32, abstime, tv_sec);
  986                 CP(abstime32, abstime, tv_nsec);
  987                 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0)
  988                         return (EINVAL);
  989                 ts = &abstime;
  990         }
  991         return (kern_sem_wait(td, uap->id, 0, ts));
  992 }
  993 
  994 static struct syscall_helper_data ksem32_syscalls[] = {
  995         SYSCALL32_INIT_HELPER(freebsd32_ksem_init),
  996         SYSCALL32_INIT_HELPER(freebsd32_ksem_open),
  997         SYSCALL32_INIT_HELPER_COMPAT(ksem_unlink),
  998         SYSCALL32_INIT_HELPER_COMPAT(ksem_close),
  999         SYSCALL32_INIT_HELPER_COMPAT(ksem_post),
 1000         SYSCALL32_INIT_HELPER_COMPAT(ksem_wait),
 1001         SYSCALL32_INIT_HELPER(freebsd32_ksem_timedwait),
 1002         SYSCALL32_INIT_HELPER_COMPAT(ksem_trywait),
 1003         SYSCALL32_INIT_HELPER_COMPAT(ksem_getvalue),
 1004         SYSCALL32_INIT_HELPER_COMPAT(ksem_destroy),
 1005         SYSCALL_INIT_LAST
 1006 };
 1007 #endif
 1008 
 1009 static int
 1010 ksem_module_init(void)
 1011 {
 1012         int error;
 1013 
 1014         mtx_init(&sem_lock, "sem", NULL, MTX_DEF);
 1015         mtx_init(&ksem_count_lock, "ksem count", NULL, MTX_DEF);
 1016         sx_init(&ksem_dict_lock, "ksem dictionary");
 1017         ksem_dictionary = hashinit(1024, M_KSEM, &ksem_hash);
 1018         p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 200112L);
 1019         p31b_setcfg(CTL_P1003_1B_SEM_NSEMS_MAX, SEM_MAX);
 1020         p31b_setcfg(CTL_P1003_1B_SEM_VALUE_MAX, SEM_VALUE_MAX);
 1021 
 1022         error = syscall_helper_register(ksem_syscalls);
 1023         if (error)
 1024                 return (error);
 1025 #ifdef COMPAT_FREEBSD32
 1026         error = syscall32_helper_register(ksem32_syscalls);
 1027         if (error)
 1028                 return (error);
 1029 #endif
 1030         return (0);
 1031 }
 1032 
 1033 static void
 1034 ksem_module_destroy(void)
 1035 {
 1036 
 1037 #ifdef COMPAT_FREEBSD32
 1038         syscall32_helper_unregister(ksem32_syscalls);
 1039 #endif
 1040         syscall_helper_unregister(ksem_syscalls);
 1041 
 1042         p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 0);
 1043         hashdestroy(ksem_dictionary, M_KSEM, ksem_hash);
 1044         sx_destroy(&ksem_dict_lock);
 1045         mtx_destroy(&ksem_count_lock);
 1046         mtx_destroy(&sem_lock);
 1047         p31b_unsetcfg(CTL_P1003_1B_SEM_VALUE_MAX);
 1048         p31b_unsetcfg(CTL_P1003_1B_SEM_NSEMS_MAX);
 1049 }
 1050 
 1051 static int
 1052 sem_modload(struct module *module, int cmd, void *arg)
 1053 {
 1054         int error = 0;
 1055 
 1056         switch (cmd) {
 1057         case MOD_LOAD:
 1058                 error = ksem_module_init();
 1059                 if (error)
 1060                         ksem_module_destroy();
 1061                 break;
 1062 
 1063         case MOD_UNLOAD:
 1064                 mtx_lock(&ksem_count_lock);
 1065                 if (nsems != 0) {
 1066                         error = EOPNOTSUPP;
 1067                         mtx_unlock(&ksem_count_lock);
 1068                         break;
 1069                 }
 1070                 ksem_dead = 1;
 1071                 mtx_unlock(&ksem_count_lock);
 1072                 ksem_module_destroy();
 1073                 break;
 1074 
 1075         case MOD_SHUTDOWN:
 1076                 break;
 1077         default:
 1078                 error = EINVAL;
 1079                 break;
 1080         }
 1081         return (error);
 1082 }
 1083 
 1084 static moduledata_t sem_mod = {
 1085         "sem",
 1086         &sem_modload,
 1087         NULL
 1088 };
 1089 
 1090 DECLARE_MODULE(sem, sem_mod, SI_SUB_SYSV_SEM, SI_ORDER_FIRST);
 1091 MODULE_VERSION(sem, 1);

Cache object: 6cd93fbf5dce95e7f5cf47d1d895fac9


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