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  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    3  *
    4  * Copyright (c) 2002 Alfred Perlstein <alfred@FreeBSD.org>
    5  * Copyright (c) 2003-2005 SPARTA, Inc.
    6  * Copyright (c) 2005, 2016-2017 Robert N. M. Watson
    7  * All rights reserved.
    8  *
    9  * This software was developed for the FreeBSD Project in part by Network
   10  * Associates Laboratories, the Security Research Division of Network
   11  * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"),
   12  * as part of the DARPA CHATS research program.
   13  *
   14  * Portions of this software were developed by BAE Systems, the University of
   15  * Cambridge Computer Laboratory, and Memorial University under DARPA/AFRL
   16  * contract FA8650-15-C-7558 ("CADETS"), as part of the DARPA Transparent
   17  * Computing (TC) research program.
   18  *
   19  * Redistribution and use in source and binary forms, with or without
   20  * modification, are permitted provided that the following conditions
   21  * are met:
   22  * 1. Redistributions of source code must retain the above copyright
   23  *    notice, this list of conditions and the following disclaimer.
   24  * 2. Redistributions in binary form must reproduce the above copyright
   25  *    notice, this list of conditions and the following disclaimer in the
   26  *    documentation and/or other materials provided with the distribution.
   27  *
   28  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   38  * SUCH DAMAGE.
   39  */
   40 
   41 #include <sys/cdefs.h>
   42 __FBSDID("$FreeBSD$");
   43 
   44 #include "opt_posix.h"
   45 
   46 #include <sys/param.h>
   47 #include <sys/capsicum.h>
   48 #include <sys/condvar.h>
   49 #include <sys/fcntl.h>
   50 #include <sys/file.h>
   51 #include <sys/filedesc.h>
   52 #include <sys/fnv_hash.h>
   53 #include <sys/jail.h>
   54 #include <sys/kernel.h>
   55 #include <sys/ksem.h>
   56 #include <sys/lock.h>
   57 #include <sys/malloc.h>
   58 #include <sys/module.h>
   59 #include <sys/mutex.h>
   60 #include <sys/priv.h>
   61 #include <sys/proc.h>
   62 #include <sys/posix4.h>
   63 #include <sys/_semaphore.h>
   64 #include <sys/stat.h>
   65 #include <sys/syscall.h>
   66 #include <sys/syscallsubr.h>
   67 #include <sys/sysctl.h>
   68 #include <sys/sysent.h>
   69 #include <sys/sysproto.h>
   70 #include <sys/systm.h>
   71 #include <sys/sx.h>
   72 #include <sys/user.h>
   73 #include <sys/vnode.h>
   74 
   75 #include <security/audit/audit.h>
   76 #include <security/mac/mac_framework.h>
   77 
   78 FEATURE(p1003_1b_semaphores, "POSIX P1003.1B semaphores support");
   79 /*
   80  * TODO
   81  *
   82  * - Resource limits?
   83  * - Replace global sem_lock with mtx_pool locks?
   84  * - Add a MAC check_create() hook for creating new named semaphores.
   85  */
   86 
   87 #ifndef SEM_MAX
   88 #define SEM_MAX 30
   89 #endif
   90 
   91 #ifdef SEM_DEBUG
   92 #define DP(x)   printf x
   93 #else
   94 #define DP(x)
   95 #endif
   96 
   97 struct ksem_mapping {
   98         char            *km_path;
   99         Fnv32_t         km_fnv;
  100         struct ksem     *km_ksem;
  101         LIST_ENTRY(ksem_mapping) km_link;
  102 };
  103 
  104 static MALLOC_DEFINE(M_KSEM, "ksem", "semaphore file descriptor");
  105 static LIST_HEAD(, ksem_mapping) *ksem_dictionary;
  106 static struct sx ksem_dict_lock;
  107 static struct mtx ksem_count_lock;
  108 static struct mtx sem_lock;
  109 static u_long ksem_hash;
  110 static int ksem_dead;
  111 
  112 #define KSEM_HASH(fnv)  (&ksem_dictionary[(fnv) & ksem_hash])
  113 
  114 static int nsems = 0;
  115 SYSCTL_DECL(_p1003_1b);
  116 SYSCTL_INT(_p1003_1b, OID_AUTO, nsems, CTLFLAG_RD, &nsems, 0,
  117     "Number of active kernel POSIX semaphores");
  118 
  119 static int      kern_sem_wait(struct thread *td, semid_t id, int tryflag,
  120                     struct timespec *abstime);
  121 static int      ksem_access(struct ksem *ks, struct ucred *ucred);
  122 static struct ksem *ksem_alloc(struct ucred *ucred, mode_t mode,
  123                     unsigned int value);
  124 static int      ksem_create(struct thread *td, const char *path,
  125                     semid_t *semidp, mode_t mode, unsigned int value,
  126                     int flags, int compat32);
  127 static void     ksem_drop(struct ksem *ks);
  128 static int      ksem_get(struct thread *td, semid_t id, cap_rights_t *rightsp,
  129     struct file **fpp);
  130 static struct ksem *ksem_hold(struct ksem *ks);
  131 static void     ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks);
  132 static struct ksem *ksem_lookup(char *path, Fnv32_t fnv);
  133 static void     ksem_module_destroy(void);
  134 static int      ksem_module_init(void);
  135 static int      ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
  136 static int      sem_modload(struct module *module, int cmd, void *arg);
  137 
  138 static fo_stat_t        ksem_stat;
  139 static fo_close_t       ksem_closef;
  140 static fo_chmod_t       ksem_chmod;
  141 static fo_chown_t       ksem_chown;
  142 static fo_fill_kinfo_t  ksem_fill_kinfo;
  143 
  144 /* File descriptor operations. */
  145 static struct fileops ksem_ops = {
  146         .fo_read = invfo_rdwr,
  147         .fo_write = invfo_rdwr,
  148         .fo_truncate = invfo_truncate,
  149         .fo_ioctl = invfo_ioctl,
  150         .fo_poll = invfo_poll,
  151         .fo_kqfilter = invfo_kqfilter,
  152         .fo_stat = ksem_stat,
  153         .fo_close = ksem_closef,
  154         .fo_chmod = ksem_chmod,
  155         .fo_chown = ksem_chown,
  156         .fo_sendfile = invfo_sendfile,
  157         .fo_fill_kinfo = ksem_fill_kinfo,
  158         .fo_flags = DFLAG_PASSABLE
  159 };
  160 
  161 FEATURE(posix_sem, "POSIX semaphores");
  162 
  163 static int
  164 ksem_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
  165     struct thread *td)
  166 {
  167         struct ksem *ks;
  168 #ifdef MAC
  169         int error;
  170 #endif
  171 
  172         ks = fp->f_data;
  173 
  174 #ifdef MAC
  175         error = mac_posixsem_check_stat(active_cred, fp->f_cred, ks);
  176         if (error)
  177                 return (error);
  178 #endif
  179         
  180         /*
  181          * Attempt to return sanish values for fstat() on a semaphore
  182          * file descriptor.
  183          */
  184         bzero(sb, sizeof(*sb));
  185 
  186         mtx_lock(&sem_lock);
  187         sb->st_atim = ks->ks_atime;
  188         sb->st_ctim = ks->ks_ctime;
  189         sb->st_mtim = ks->ks_mtime;
  190         sb->st_birthtim = ks->ks_birthtime;
  191         sb->st_uid = ks->ks_uid;
  192         sb->st_gid = ks->ks_gid;
  193         sb->st_mode = S_IFREG | ks->ks_mode;            /* XXX */
  194         mtx_unlock(&sem_lock);
  195 
  196         return (0);
  197 }
  198 
  199 static int
  200 ksem_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
  201     struct thread *td)
  202 {
  203         struct ksem *ks;
  204         int error;
  205 
  206         error = 0;
  207         ks = fp->f_data;
  208         mtx_lock(&sem_lock);
  209 #ifdef MAC
  210         error = mac_posixsem_check_setmode(active_cred, ks, mode);
  211         if (error != 0)
  212                 goto out;
  213 #endif
  214         error = vaccess(VREG, ks->ks_mode, ks->ks_uid, ks->ks_gid, VADMIN,
  215             active_cred, NULL);
  216         if (error != 0)
  217                 goto out;
  218         ks->ks_mode = mode & ACCESSPERMS;
  219 out:
  220         mtx_unlock(&sem_lock);
  221         return (error);
  222 }
  223 
  224 static int
  225 ksem_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
  226     struct thread *td)
  227 {
  228         struct ksem *ks;
  229         int error;
  230 
  231         error = 0;
  232         ks = fp->f_data;
  233         mtx_lock(&sem_lock);
  234 #ifdef MAC
  235         error = mac_posixsem_check_setowner(active_cred, ks, uid, gid);
  236         if (error != 0)
  237                 goto out;
  238 #endif
  239         if (uid == (uid_t)-1)
  240                 uid = ks->ks_uid;
  241         if (gid == (gid_t)-1)
  242                  gid = ks->ks_gid;
  243         if (((uid != ks->ks_uid && uid != active_cred->cr_uid) ||
  244             (gid != ks->ks_gid && !groupmember(gid, active_cred))) &&
  245             (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN, 0)))
  246                 goto out;
  247         ks->ks_uid = uid;
  248         ks->ks_gid = gid;
  249 out:
  250         mtx_unlock(&sem_lock);
  251         return (error);
  252 }
  253 
  254 static int
  255 ksem_closef(struct file *fp, struct thread *td)
  256 {
  257         struct ksem *ks;
  258 
  259         ks = fp->f_data;
  260         fp->f_data = NULL;
  261         ksem_drop(ks);
  262 
  263         return (0);
  264 }
  265 
  266 static int
  267 ksem_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp)
  268 {
  269         const char *path, *pr_path;
  270         struct ksem *ks;
  271         size_t pr_pathlen;
  272 
  273         kif->kf_type = KF_TYPE_SEM;
  274         ks = fp->f_data;
  275         mtx_lock(&sem_lock);
  276         kif->kf_un.kf_sem.kf_sem_value = ks->ks_value;
  277         kif->kf_un.kf_sem.kf_sem_mode = S_IFREG | ks->ks_mode;  /* XXX */
  278         mtx_unlock(&sem_lock);
  279         if (ks->ks_path != NULL) {
  280                 sx_slock(&ksem_dict_lock);
  281                 if (ks->ks_path != NULL) {
  282                         path = ks->ks_path;
  283                         pr_path = curthread->td_ucred->cr_prison->pr_path;
  284                         if (strcmp(pr_path, "/") != 0) {
  285                                 /* Return the jail-rooted pathname. */
  286                                 pr_pathlen = strlen(pr_path);
  287                                 if (strncmp(path, pr_path, pr_pathlen) == 0 &&
  288                                     path[pr_pathlen] == '/')
  289                                         path += pr_pathlen;
  290                         }
  291                         strlcpy(kif->kf_path, path, sizeof(kif->kf_path));
  292                 }
  293                 sx_sunlock(&ksem_dict_lock);
  294         }
  295         return (0);
  296 }
  297 
  298 /*
  299  * ksem object management including creation and reference counting
  300  * routines.
  301  */
  302 static struct ksem *
  303 ksem_alloc(struct ucred *ucred, mode_t mode, unsigned int value)
  304 {
  305         struct ksem *ks;
  306 
  307         mtx_lock(&ksem_count_lock);
  308         if (nsems == p31b_getcfg(CTL_P1003_1B_SEM_NSEMS_MAX) || ksem_dead) {
  309                 mtx_unlock(&ksem_count_lock);
  310                 return (NULL);
  311         }
  312         nsems++;
  313         mtx_unlock(&ksem_count_lock);
  314         ks = malloc(sizeof(*ks), M_KSEM, M_WAITOK | M_ZERO);
  315         ks->ks_uid = ucred->cr_uid;
  316         ks->ks_gid = ucred->cr_gid;
  317         ks->ks_mode = mode;
  318         ks->ks_value = value;
  319         cv_init(&ks->ks_cv, "ksem");
  320         vfs_timestamp(&ks->ks_birthtime);
  321         ks->ks_atime = ks->ks_mtime = ks->ks_ctime = ks->ks_birthtime;
  322         refcount_init(&ks->ks_ref, 1);
  323 #ifdef MAC
  324         mac_posixsem_init(ks);
  325         mac_posixsem_create(ucred, ks);
  326 #endif
  327 
  328         return (ks);
  329 }
  330 
  331 static struct ksem *
  332 ksem_hold(struct ksem *ks)
  333 {
  334 
  335         refcount_acquire(&ks->ks_ref);
  336         return (ks);
  337 }
  338 
  339 static void
  340 ksem_drop(struct ksem *ks)
  341 {
  342 
  343         if (refcount_release(&ks->ks_ref)) {
  344 #ifdef MAC
  345                 mac_posixsem_destroy(ks);
  346 #endif
  347                 cv_destroy(&ks->ks_cv);
  348                 free(ks, M_KSEM);
  349                 mtx_lock(&ksem_count_lock);
  350                 nsems--;
  351                 mtx_unlock(&ksem_count_lock);
  352         }
  353 }
  354 
  355 /*
  356  * Determine if the credentials have sufficient permissions for read
  357  * and write access.
  358  */
  359 static int
  360 ksem_access(struct ksem *ks, struct ucred *ucred)
  361 {
  362         int error;
  363 
  364         error = vaccess(VREG, ks->ks_mode, ks->ks_uid, ks->ks_gid,
  365             VREAD | VWRITE, ucred, NULL);
  366         if (error)
  367                 error = priv_check_cred(ucred, PRIV_SEM_WRITE, 0);
  368         return (error);
  369 }
  370 
  371 /*
  372  * Dictionary management.  We maintain an in-kernel dictionary to map
  373  * paths to semaphore objects.  We use the FNV hash on the path to
  374  * store the mappings in a hash table.
  375  */
  376 static struct ksem *
  377 ksem_lookup(char *path, Fnv32_t fnv)
  378 {
  379         struct ksem_mapping *map;
  380 
  381         LIST_FOREACH(map, KSEM_HASH(fnv), km_link) {
  382                 if (map->km_fnv != fnv)
  383                         continue;
  384                 if (strcmp(map->km_path, path) == 0)
  385                         return (map->km_ksem);
  386         }
  387 
  388         return (NULL);
  389 }
  390 
  391 static void
  392 ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks)
  393 {
  394         struct ksem_mapping *map;
  395 
  396         map = malloc(sizeof(struct ksem_mapping), M_KSEM, M_WAITOK);
  397         map->km_path = path;
  398         map->km_fnv = fnv;
  399         map->km_ksem = ksem_hold(ks);
  400         ks->ks_path = path;
  401         LIST_INSERT_HEAD(KSEM_HASH(fnv), map, km_link);
  402 }
  403 
  404 static int
  405 ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
  406 {
  407         struct ksem_mapping *map;
  408         int error;
  409 
  410         LIST_FOREACH(map, KSEM_HASH(fnv), km_link) {
  411                 if (map->km_fnv != fnv)
  412                         continue;
  413                 if (strcmp(map->km_path, path) == 0) {
  414 #ifdef MAC
  415                         error = mac_posixsem_check_unlink(ucred, map->km_ksem);
  416                         if (error)
  417                                 return (error);
  418 #endif
  419                         error = ksem_access(map->km_ksem, ucred);
  420                         if (error)
  421                                 return (error);
  422                         map->km_ksem->ks_path = NULL;
  423                         LIST_REMOVE(map, km_link);
  424                         ksem_drop(map->km_ksem);
  425                         free(map->km_path, M_KSEM);
  426                         free(map, M_KSEM);
  427                         return (0);
  428                 }
  429         }
  430 
  431         return (ENOENT);
  432 }
  433 
  434 static int
  435 ksem_create_copyout_semid(struct thread *td, semid_t *semidp, int fd,
  436     int compat32)
  437 {
  438         semid_t semid;
  439 #ifdef COMPAT_FREEBSD32
  440         int32_t semid32;
  441 #endif
  442         void *ptr;
  443         size_t ptrs;
  444 
  445 #ifdef COMPAT_FREEBSD32
  446         if (compat32) {
  447                 semid32 = fd;
  448                 ptr = &semid32;
  449                 ptrs = sizeof(semid32);
  450         } else {
  451 #endif
  452                 semid = fd;
  453                 ptr = &semid;
  454                 ptrs = sizeof(semid);
  455                 compat32 = 0; /* silence gcc */
  456 #ifdef COMPAT_FREEBSD32
  457         }
  458 #endif
  459 
  460         return (copyout(ptr, semidp, ptrs));
  461 }
  462 
  463 /* Other helper routines. */
  464 static int
  465 ksem_create(struct thread *td, const char *name, semid_t *semidp, mode_t mode,
  466     unsigned int value, int flags, int compat32)
  467 {
  468         struct filedesc *fdp;
  469         struct ksem *ks;
  470         struct file *fp;
  471         char *path;
  472         const char *pr_path;
  473         size_t pr_pathlen;
  474         Fnv32_t fnv;
  475         int error, fd;
  476 
  477         AUDIT_ARG_FFLAGS(flags);
  478         AUDIT_ARG_MODE(mode);
  479         AUDIT_ARG_VALUE(value);
  480 
  481         if (value > SEM_VALUE_MAX)
  482                 return (EINVAL);
  483 
  484         fdp = td->td_proc->p_fd;
  485         mode = (mode & ~fdp->fd_cmask) & ACCESSPERMS;
  486         error = falloc(td, &fp, &fd, O_CLOEXEC);
  487         if (error) {
  488                 if (name == NULL)
  489                         error = ENOSPC;
  490                 return (error);
  491         }
  492 
  493         /*
  494          * Go ahead and copyout the file descriptor now.  This is a bit
  495          * premature, but it is a lot easier to handle errors as opposed
  496          * to later when we've possibly created a new semaphore, etc.
  497          */
  498         error = ksem_create_copyout_semid(td, semidp, fd, compat32);
  499         if (error) {
  500                 fdclose(td, fp, fd);
  501                 fdrop(fp, td);
  502                 return (error);
  503         }
  504 
  505         if (name == NULL) {
  506                 /* Create an anonymous semaphore. */
  507                 ks = ksem_alloc(td->td_ucred, mode, value);
  508                 if (ks == NULL)
  509                         error = ENOSPC;
  510                 else
  511                         ks->ks_flags |= KS_ANONYMOUS;
  512         } else {
  513                 path = malloc(MAXPATHLEN, M_KSEM, M_WAITOK);
  514                 pr_path = td->td_ucred->cr_prison->pr_path;
  515 
  516                 /* Construct a full pathname for jailed callers. */
  517                 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0
  518                     : strlcpy(path, pr_path, MAXPATHLEN);
  519                 error = copyinstr(name, path + pr_pathlen,
  520                     MAXPATHLEN - pr_pathlen, NULL);
  521 
  522                 /* Require paths to start with a '/' character. */
  523                 if (error == 0 && path[pr_pathlen] != '/')
  524                         error = EINVAL;
  525                 if (error) {
  526                         fdclose(td, fp, fd);
  527                         fdrop(fp, td);
  528                         free(path, M_KSEM);
  529                         return (error);
  530                 }
  531 
  532                 AUDIT_ARG_UPATH1_CANON(path);
  533                 fnv = fnv_32_str(path, FNV1_32_INIT);
  534                 sx_xlock(&ksem_dict_lock);
  535                 ks = ksem_lookup(path, fnv);
  536                 if (ks == NULL) {
  537                         /* Object does not exist, create it if requested. */
  538                         if (flags & O_CREAT) {
  539                                 ks = ksem_alloc(td->td_ucred, mode, value);
  540                                 if (ks == NULL)
  541                                         error = ENFILE;
  542                                 else {
  543                                         ksem_insert(path, fnv, ks);
  544                                         path = NULL;
  545                                 }
  546                         } else
  547                                 error = ENOENT;
  548                 } else {
  549                         /*
  550                          * Object already exists, obtain a new
  551                          * reference if requested and permitted.
  552                          */
  553                         if ((flags & (O_CREAT | O_EXCL)) ==
  554                             (O_CREAT | O_EXCL))
  555                                 error = EEXIST;
  556                         else {
  557 #ifdef MAC
  558                                 error = mac_posixsem_check_open(td->td_ucred,
  559                                     ks);
  560                                 if (error == 0)
  561 #endif
  562                                 error = ksem_access(ks, td->td_ucred);
  563                         }
  564                         if (error == 0)
  565                                 ksem_hold(ks);
  566 #ifdef INVARIANTS
  567                         else
  568                                 ks = NULL;
  569 #endif
  570                 }
  571                 sx_xunlock(&ksem_dict_lock);
  572                 if (path)
  573                         free(path, M_KSEM);
  574         }
  575 
  576         if (error) {
  577                 KASSERT(ks == NULL, ("ksem_create error with a ksem"));
  578                 fdclose(td, fp, fd);
  579                 fdrop(fp, td);
  580                 return (error);
  581         }
  582         KASSERT(ks != NULL, ("ksem_create w/o a ksem"));
  583 
  584         finit(fp, FREAD | FWRITE, DTYPE_SEM, ks, &ksem_ops);
  585 
  586         fdrop(fp, td);
  587 
  588         return (0);
  589 }
  590 
  591 static int
  592 ksem_get(struct thread *td, semid_t id, cap_rights_t *rightsp,
  593     struct file **fpp)
  594 {
  595         struct ksem *ks;
  596         struct file *fp;
  597         int error;
  598 
  599         error = fget(td, id, rightsp, &fp);
  600         if (error)
  601                 return (EINVAL);
  602         if (fp->f_type != DTYPE_SEM) {
  603                 fdrop(fp, td);
  604                 return (EINVAL);
  605         }
  606         ks = fp->f_data;
  607         if (ks->ks_flags & KS_DEAD) {
  608                 fdrop(fp, td);
  609                 return (EINVAL);
  610         }
  611         *fpp = fp;
  612         return (0);
  613 }
  614 
  615 /* System calls. */
  616 #ifndef _SYS_SYSPROTO_H_
  617 struct ksem_init_args {
  618         unsigned int    value;
  619         semid_t         *idp;
  620 };
  621 #endif
  622 int
  623 sys_ksem_init(struct thread *td, struct ksem_init_args *uap)
  624 {
  625 
  626         return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value,
  627             0, 0));
  628 }
  629 
  630 #ifndef _SYS_SYSPROTO_H_
  631 struct ksem_open_args {
  632         char            *name;
  633         int             oflag;
  634         mode_t          mode;
  635         unsigned int    value;
  636         semid_t         *idp;   
  637 };
  638 #endif
  639 int
  640 sys_ksem_open(struct thread *td, struct ksem_open_args *uap)
  641 {
  642 
  643         DP((">>> ksem_open start, pid=%d\n", (int)td->td_proc->p_pid));
  644 
  645         if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0)
  646                 return (EINVAL);
  647         return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value,
  648             uap->oflag, 0));
  649 }
  650 
  651 #ifndef _SYS_SYSPROTO_H_
  652 struct ksem_unlink_args {
  653         char            *name;
  654 };
  655 #endif
  656 int
  657 sys_ksem_unlink(struct thread *td, struct ksem_unlink_args *uap)
  658 {
  659         char *path;
  660         const char *pr_path;
  661         size_t pr_pathlen;
  662         Fnv32_t fnv;
  663         int error;
  664 
  665         path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
  666         pr_path = td->td_ucred->cr_prison->pr_path;
  667         pr_pathlen = strcmp(pr_path, "/") == 0 ? 0
  668             : strlcpy(path, pr_path, MAXPATHLEN);
  669         error = copyinstr(uap->name, path + pr_pathlen, MAXPATHLEN - pr_pathlen,
  670             NULL);
  671         if (error) {
  672                 free(path, M_TEMP);
  673                 return (error);
  674         }
  675 
  676         AUDIT_ARG_UPATH1_CANON(path);
  677         fnv = fnv_32_str(path, FNV1_32_INIT);
  678         sx_xlock(&ksem_dict_lock);
  679         error = ksem_remove(path, fnv, td->td_ucred);
  680         sx_xunlock(&ksem_dict_lock);
  681         free(path, M_TEMP);
  682 
  683         return (error);
  684 }
  685 
  686 #ifndef _SYS_SYSPROTO_H_
  687 struct ksem_close_args {
  688         semid_t         id;
  689 };
  690 #endif
  691 int
  692 sys_ksem_close(struct thread *td, struct ksem_close_args *uap)
  693 {
  694         struct ksem *ks;
  695         struct file *fp;
  696         int error;
  697 
  698         /* No capability rights required to close a semaphore. */
  699         AUDIT_ARG_FD(uap->id);
  700         error = ksem_get(td, uap->id, &cap_no_rights, &fp);
  701         if (error)
  702                 return (error);
  703         ks = fp->f_data;
  704         if (ks->ks_flags & KS_ANONYMOUS) {
  705                 fdrop(fp, td);
  706                 return (EINVAL);
  707         }
  708         error = kern_close(td, uap->id);
  709         fdrop(fp, td);
  710         return (error);
  711 }
  712 
  713 #ifndef _SYS_SYSPROTO_H_
  714 struct ksem_post_args {
  715         semid_t id;
  716 };
  717 #endif
  718 int
  719 sys_ksem_post(struct thread *td, struct ksem_post_args *uap)
  720 {
  721         cap_rights_t rights;
  722         struct file *fp;
  723         struct ksem *ks;
  724         int error;
  725 
  726         AUDIT_ARG_FD(uap->id);
  727         error = ksem_get(td, uap->id,
  728             cap_rights_init(&rights, CAP_SEM_POST), &fp);
  729         if (error)
  730                 return (error);
  731         ks = fp->f_data;
  732 
  733         mtx_lock(&sem_lock);
  734 #ifdef MAC
  735         error = mac_posixsem_check_post(td->td_ucred, fp->f_cred, ks);
  736         if (error)
  737                 goto err;
  738 #endif
  739         if (ks->ks_value == SEM_VALUE_MAX) {
  740                 error = EOVERFLOW;
  741                 goto err;
  742         }
  743         ++ks->ks_value;
  744         if (ks->ks_waiters > 0)
  745                 cv_signal(&ks->ks_cv);
  746         error = 0;
  747         vfs_timestamp(&ks->ks_ctime);
  748 err:
  749         mtx_unlock(&sem_lock);
  750         fdrop(fp, td);
  751         return (error);
  752 }
  753 
  754 #ifndef _SYS_SYSPROTO_H_
  755 struct ksem_wait_args {
  756         semid_t         id;
  757 };
  758 #endif
  759 int
  760 sys_ksem_wait(struct thread *td, struct ksem_wait_args *uap)
  761 {
  762 
  763         return (kern_sem_wait(td, uap->id, 0, NULL));
  764 }
  765 
  766 #ifndef _SYS_SYSPROTO_H_
  767 struct ksem_timedwait_args {
  768         semid_t         id;
  769         const struct timespec *abstime;
  770 };
  771 #endif
  772 int
  773 sys_ksem_timedwait(struct thread *td, struct ksem_timedwait_args *uap)
  774 {
  775         struct timespec abstime;
  776         struct timespec *ts;
  777         int error;
  778 
  779         /*
  780          * We allow a null timespec (wait forever).
  781          */
  782         if (uap->abstime == NULL)
  783                 ts = NULL;
  784         else {
  785                 error = copyin(uap->abstime, &abstime, sizeof(abstime));
  786                 if (error != 0)
  787                         return (error);
  788                 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0)
  789                         return (EINVAL);
  790                 ts = &abstime;
  791         }
  792         return (kern_sem_wait(td, uap->id, 0, ts));
  793 }
  794 
  795 #ifndef _SYS_SYSPROTO_H_
  796 struct ksem_trywait_args {
  797         semid_t         id;
  798 };
  799 #endif
  800 int
  801 sys_ksem_trywait(struct thread *td, struct ksem_trywait_args *uap)
  802 {
  803 
  804         return (kern_sem_wait(td, uap->id, 1, NULL));
  805 }
  806 
  807 static int
  808 kern_sem_wait(struct thread *td, semid_t id, int tryflag,
  809     struct timespec *abstime)
  810 {
  811         struct timespec ts1, ts2;
  812         struct timeval tv;
  813         cap_rights_t rights;
  814         struct file *fp;
  815         struct ksem *ks;
  816         int error;
  817 
  818         DP((">>> kern_sem_wait entered! pid=%d\n", (int)td->td_proc->p_pid));
  819         AUDIT_ARG_FD(id);
  820         error = ksem_get(td, id, cap_rights_init(&rights, CAP_SEM_WAIT), &fp);
  821         if (error)
  822                 return (error);
  823         ks = fp->f_data;
  824         mtx_lock(&sem_lock);
  825         DP((">>> kern_sem_wait critical section entered! pid=%d\n",
  826             (int)td->td_proc->p_pid));
  827 #ifdef MAC
  828         error = mac_posixsem_check_wait(td->td_ucred, fp->f_cred, ks);
  829         if (error) {
  830                 DP(("kern_sem_wait mac failed\n"));
  831                 goto err;
  832         }
  833 #endif
  834         DP(("kern_sem_wait value = %d, tryflag %d\n", ks->ks_value, tryflag));
  835         vfs_timestamp(&ks->ks_atime);
  836         while (ks->ks_value == 0) {
  837                 ks->ks_waiters++;
  838                 if (tryflag != 0)
  839                         error = EAGAIN;
  840                 else if (abstime == NULL)
  841                         error = cv_wait_sig(&ks->ks_cv, &sem_lock);
  842                 else {
  843                         for (;;) {
  844                                 ts1 = *abstime;
  845                                 getnanotime(&ts2);
  846                                 timespecsub(&ts1, &ts2, &ts1);
  847                                 TIMESPEC_TO_TIMEVAL(&tv, &ts1);
  848                                 if (tv.tv_sec < 0) {
  849                                         error = ETIMEDOUT;
  850                                         break;
  851                                 }
  852                                 error = cv_timedwait_sig(&ks->ks_cv,
  853                                     &sem_lock, tvtohz(&tv));
  854                                 if (error != EWOULDBLOCK)
  855                                         break;
  856                         }
  857                 }
  858                 ks->ks_waiters--;
  859                 if (error)
  860                         goto err;
  861         }
  862         ks->ks_value--;
  863         DP(("kern_sem_wait value post-decrement = %d\n", ks->ks_value));
  864         error = 0;
  865 err:
  866         mtx_unlock(&sem_lock);
  867         fdrop(fp, td);
  868         DP(("<<< kern_sem_wait leaving, pid=%d, error = %d\n",
  869             (int)td->td_proc->p_pid, error));
  870         return (error);
  871 }
  872 
  873 #ifndef _SYS_SYSPROTO_H_
  874 struct ksem_getvalue_args {
  875         semid_t         id;
  876         int             *val;
  877 };
  878 #endif
  879 int
  880 sys_ksem_getvalue(struct thread *td, struct ksem_getvalue_args *uap)
  881 {
  882         cap_rights_t rights;
  883         struct file *fp;
  884         struct ksem *ks;
  885         int error, val;
  886 
  887         AUDIT_ARG_FD(uap->id);
  888         error = ksem_get(td, uap->id,
  889             cap_rights_init(&rights, CAP_SEM_GETVALUE), &fp);
  890         if (error)
  891                 return (error);
  892         ks = fp->f_data;
  893 
  894         mtx_lock(&sem_lock);
  895 #ifdef MAC
  896         error = mac_posixsem_check_getvalue(td->td_ucred, fp->f_cred, ks);
  897         if (error) {
  898                 mtx_unlock(&sem_lock);
  899                 fdrop(fp, td);
  900                 return (error);
  901         }
  902 #endif
  903         val = ks->ks_value;
  904         vfs_timestamp(&ks->ks_atime);
  905         mtx_unlock(&sem_lock);
  906         fdrop(fp, td);
  907         error = copyout(&val, uap->val, sizeof(val));
  908         return (error);
  909 }
  910 
  911 #ifndef _SYS_SYSPROTO_H_
  912 struct ksem_destroy_args {
  913         semid_t         id;
  914 };
  915 #endif
  916 int
  917 sys_ksem_destroy(struct thread *td, struct ksem_destroy_args *uap)
  918 {
  919         struct file *fp;
  920         struct ksem *ks;
  921         int error;
  922 
  923         /* No capability rights required to close a semaphore. */
  924         AUDIT_ARG_FD(uap->id);
  925         error = ksem_get(td, uap->id, &cap_no_rights, &fp);
  926         if (error)
  927                 return (error);
  928         ks = fp->f_data;
  929         if (!(ks->ks_flags & KS_ANONYMOUS)) {
  930                 fdrop(fp, td);
  931                 return (EINVAL);
  932         }
  933         mtx_lock(&sem_lock);
  934         if (ks->ks_waiters != 0) {
  935                 mtx_unlock(&sem_lock);
  936                 error = EBUSY;
  937                 goto err;
  938         }
  939         ks->ks_flags |= KS_DEAD;
  940         mtx_unlock(&sem_lock);
  941 
  942         error = kern_close(td, uap->id);
  943 err:
  944         fdrop(fp, td);
  945         return (error);
  946 }
  947 
  948 static struct syscall_helper_data ksem_syscalls[] = {
  949         SYSCALL_INIT_HELPER(ksem_init),
  950         SYSCALL_INIT_HELPER(ksem_open),
  951         SYSCALL_INIT_HELPER(ksem_unlink),
  952         SYSCALL_INIT_HELPER(ksem_close),
  953         SYSCALL_INIT_HELPER(ksem_post),
  954         SYSCALL_INIT_HELPER(ksem_wait),
  955         SYSCALL_INIT_HELPER(ksem_timedwait),
  956         SYSCALL_INIT_HELPER(ksem_trywait),
  957         SYSCALL_INIT_HELPER(ksem_getvalue),
  958         SYSCALL_INIT_HELPER(ksem_destroy),
  959         SYSCALL_INIT_LAST
  960 };
  961 
  962 #ifdef COMPAT_FREEBSD32
  963 #include <compat/freebsd32/freebsd32.h>
  964 #include <compat/freebsd32/freebsd32_proto.h>
  965 #include <compat/freebsd32/freebsd32_signal.h>
  966 #include <compat/freebsd32/freebsd32_syscall.h>
  967 #include <compat/freebsd32/freebsd32_util.h>
  968 
  969 int
  970 freebsd32_ksem_init(struct thread *td, struct freebsd32_ksem_init_args *uap)
  971 {
  972 
  973         return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value,
  974             0, 1));
  975 }
  976 
  977 int
  978 freebsd32_ksem_open(struct thread *td, struct freebsd32_ksem_open_args *uap)
  979 {
  980 
  981         if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0)
  982                 return (EINVAL);
  983         return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value,
  984             uap->oflag, 1));
  985 }
  986 
  987 int
  988 freebsd32_ksem_timedwait(struct thread *td,
  989     struct freebsd32_ksem_timedwait_args *uap)
  990 {
  991         struct timespec32 abstime32;
  992         struct timespec *ts, abstime;
  993         int error;
  994 
  995         /*
  996          * We allow a null timespec (wait forever).
  997          */
  998         if (uap->abstime == NULL)
  999                 ts = NULL;
 1000         else {
 1001                 error = copyin(uap->abstime, &abstime32, sizeof(abstime32));
 1002                 if (error != 0)
 1003                         return (error);
 1004                 CP(abstime32, abstime, tv_sec);
 1005                 CP(abstime32, abstime, tv_nsec);
 1006                 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0)
 1007                         return (EINVAL);
 1008                 ts = &abstime;
 1009         }
 1010         return (kern_sem_wait(td, uap->id, 0, ts));
 1011 }
 1012 
 1013 static struct syscall_helper_data ksem32_syscalls[] = {
 1014         SYSCALL32_INIT_HELPER(freebsd32_ksem_init),
 1015         SYSCALL32_INIT_HELPER(freebsd32_ksem_open),
 1016         SYSCALL32_INIT_HELPER_COMPAT(ksem_unlink),
 1017         SYSCALL32_INIT_HELPER_COMPAT(ksem_close),
 1018         SYSCALL32_INIT_HELPER_COMPAT(ksem_post),
 1019         SYSCALL32_INIT_HELPER_COMPAT(ksem_wait),
 1020         SYSCALL32_INIT_HELPER(freebsd32_ksem_timedwait),
 1021         SYSCALL32_INIT_HELPER_COMPAT(ksem_trywait),
 1022         SYSCALL32_INIT_HELPER_COMPAT(ksem_getvalue),
 1023         SYSCALL32_INIT_HELPER_COMPAT(ksem_destroy),
 1024         SYSCALL_INIT_LAST
 1025 };
 1026 #endif
 1027 
 1028 static int
 1029 ksem_module_init(void)
 1030 {
 1031         int error;
 1032 
 1033         mtx_init(&sem_lock, "sem", NULL, MTX_DEF);
 1034         mtx_init(&ksem_count_lock, "ksem count", NULL, MTX_DEF);
 1035         sx_init(&ksem_dict_lock, "ksem dictionary");
 1036         ksem_dictionary = hashinit(1024, M_KSEM, &ksem_hash);
 1037         p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 200112L);
 1038         p31b_setcfg(CTL_P1003_1B_SEM_NSEMS_MAX, SEM_MAX);
 1039         p31b_setcfg(CTL_P1003_1B_SEM_VALUE_MAX, SEM_VALUE_MAX);
 1040 
 1041         error = syscall_helper_register(ksem_syscalls, SY_THR_STATIC_KLD);
 1042         if (error)
 1043                 return (error);
 1044 #ifdef COMPAT_FREEBSD32
 1045         error = syscall32_helper_register(ksem32_syscalls, SY_THR_STATIC_KLD);
 1046         if (error)
 1047                 return (error);
 1048 #endif
 1049         return (0);
 1050 }
 1051 
 1052 static void
 1053 ksem_module_destroy(void)
 1054 {
 1055 
 1056 #ifdef COMPAT_FREEBSD32
 1057         syscall32_helper_unregister(ksem32_syscalls);
 1058 #endif
 1059         syscall_helper_unregister(ksem_syscalls);
 1060 
 1061         p31b_setcfg(CTL_P1003_1B_SEMAPHORES, 0);
 1062         hashdestroy(ksem_dictionary, M_KSEM, ksem_hash);
 1063         sx_destroy(&ksem_dict_lock);
 1064         mtx_destroy(&ksem_count_lock);
 1065         mtx_destroy(&sem_lock);
 1066         p31b_unsetcfg(CTL_P1003_1B_SEM_VALUE_MAX);
 1067         p31b_unsetcfg(CTL_P1003_1B_SEM_NSEMS_MAX);
 1068 }
 1069 
 1070 static int
 1071 sem_modload(struct module *module, int cmd, void *arg)
 1072 {
 1073         int error = 0;
 1074 
 1075         switch (cmd) {
 1076         case MOD_LOAD:
 1077                 error = ksem_module_init();
 1078                 if (error)
 1079                         ksem_module_destroy();
 1080                 break;
 1081 
 1082         case MOD_UNLOAD:
 1083                 mtx_lock(&ksem_count_lock);
 1084                 if (nsems != 0) {
 1085                         error = EOPNOTSUPP;
 1086                         mtx_unlock(&ksem_count_lock);
 1087                         break;
 1088                 }
 1089                 ksem_dead = 1;
 1090                 mtx_unlock(&ksem_count_lock);
 1091                 ksem_module_destroy();
 1092                 break;
 1093 
 1094         case MOD_SHUTDOWN:
 1095                 break;
 1096         default:
 1097                 error = EINVAL;
 1098                 break;
 1099         }
 1100         return (error);
 1101 }
 1102 
 1103 static moduledata_t sem_mod = {
 1104         "sem",
 1105         &sem_modload,
 1106         NULL
 1107 };
 1108 
 1109 DECLARE_MODULE(sem, sem_mod, SI_SUB_SYSV_SEM, SI_ORDER_FIRST);
 1110 MODULE_VERSION(sem, 1);

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