devfs_devs.c

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    1 /*-
    2  * Copyright (c) 2000,2004
    3  *      Poul-Henning Kamp.  All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Neither the name of the University nor the names of its contributors
   11  *    may be used to endorse or promote products derived from this software
   12  *    without specific prior written permission.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  *
   26  * From: FreeBSD: src/sys/miscfs/kernfs/kernfs_vfsops.c 1.36
   27  *
   28  * $FreeBSD: releng/8.0/sys/fs/devfs/devfs_devs.c 193511 2009-06-05 14:55:22Z rwatson $
   29  */
   30 
   31 #include <sys/param.h>
   32 #include <sys/systm.h>
   33 #include <sys/conf.h>
   34 #include <sys/dirent.h>
   35 #include <sys/kernel.h>
   36 #include <sys/limits.h>
   37 #include <sys/lock.h>
   38 #include <sys/malloc.h>
   39 #include <sys/proc.h>
   40 #include <sys/sx.h>
   41 #include <sys/sysctl.h>
   42 #include <sys/vnode.h>
   43 
   44 #include <sys/kdb.h>
   45 
   46 #include <fs/devfs/devfs.h>
   47 #include <fs/devfs/devfs_int.h>
   48 
   49 #include <security/mac/mac_framework.h>
   50 
   51 /*
   52  * The one true (but secret) list of active devices in the system.
   53  * Locked by dev_lock()/devmtx
   54  */
   55 struct cdev_priv_list cdevp_list = TAILQ_HEAD_INITIALIZER(cdevp_list);
   56 
   57 struct unrhdr *devfs_inos;
   58 
   59 
   60 static MALLOC_DEFINE(M_DEVFS2, "DEVFS2", "DEVFS data 2");
   61 static MALLOC_DEFINE(M_DEVFS3, "DEVFS3", "DEVFS data 3");
   62 static MALLOC_DEFINE(M_CDEVP, "DEVFS1", "DEVFS cdev_priv storage");
   63 
   64 static SYSCTL_NODE(_vfs, OID_AUTO, devfs, CTLFLAG_RW, 0, "DEVFS filesystem");
   65 
   66 static unsigned devfs_generation;
   67 SYSCTL_UINT(_vfs_devfs, OID_AUTO, generation, CTLFLAG_RD,
   68         &devfs_generation, 0, "DEVFS generation number");
   69 
   70 unsigned devfs_rule_depth = 1;
   71 SYSCTL_UINT(_vfs_devfs, OID_AUTO, rule_depth, CTLFLAG_RW,
   72         &devfs_rule_depth, 0, "Max depth of ruleset include");
   73 
   74 /*
   75  * Helper sysctl for devname(3).  We're given a struct cdev * and return
   76  * the name, if any, registered by the device driver.
   77  */
   78 static int
   79 sysctl_devname(SYSCTL_HANDLER_ARGS)
   80 {
   81         int error;
   82         dev_t ud;
   83         struct cdev_priv *cdp;
   84 
   85         error = SYSCTL_IN(req, &ud, sizeof (ud));
   86         if (error)
   87                 return (error);
   88         if (ud == NODEV)
   89                 return(EINVAL);
   90 /*
   91         ud ^ devfs_random();
   92 */
   93         dev_lock();
   94         TAILQ_FOREACH(cdp, &cdevp_list, cdp_list)
   95                 if (cdp->cdp_inode == ud)
   96                         break;
   97         dev_unlock();
   98         if (cdp == NULL)
   99                 return(ENOENT);
  100         return(SYSCTL_OUT(req, cdp->cdp_c.si_name, strlen(cdp->cdp_c.si_name) + 1));
  101         return (error);
  102 }
  103 
  104 SYSCTL_PROC(_kern, OID_AUTO, devname,
  105     CTLTYPE_OPAQUE|CTLFLAG_RW|CTLFLAG_ANYBODY|CTLFLAG_MPSAFE,
  106     NULL, 0, sysctl_devname, "", "devname(3) handler");
  107 
  108 SYSCTL_INT(_debug_sizeof, OID_AUTO, cdev, CTLFLAG_RD,
  109     0, sizeof(struct cdev), "sizeof(struct cdev)");
  110 
  111 SYSCTL_INT(_debug_sizeof, OID_AUTO, cdev_priv, CTLFLAG_RD,
  112     0, sizeof(struct cdev_priv), "sizeof(struct cdev_priv)");
  113 
  114 struct cdev *
  115 devfs_alloc(void)
  116 {
  117         struct cdev_priv *cdp;
  118         struct cdev *cdev;
  119         struct timespec ts;
  120 
  121         cdp = malloc(sizeof *cdp, M_CDEVP, M_USE_RESERVE | M_ZERO | M_WAITOK);
  122 
  123         cdp->cdp_dirents = &cdp->cdp_dirent0;
  124         cdp->cdp_dirent0 = NULL;
  125         cdp->cdp_maxdirent = 0;
  126 
  127         cdev = &cdp->cdp_c;
  128 
  129         cdev->si_name = cdev->__si_namebuf;
  130         LIST_INIT(&cdev->si_children);
  131         vfs_timestamp(&ts);
  132         cdev->si_atime = cdev->si_mtime = cdev->si_ctime = ts;
  133 
  134         return (cdev);
  135 }
  136 
  137 void
  138 devfs_free(struct cdev *cdev)
  139 {
  140         struct cdev_priv *cdp;
  141 
  142         cdp = cdev2priv(cdev);
  143         if (cdev->si_cred != NULL)
  144                 crfree(cdev->si_cred);
  145         if (cdp->cdp_inode > 0)
  146                 free_unr(devfs_inos, cdp->cdp_inode);
  147         if (cdp->cdp_maxdirent > 0) 
  148                 free(cdp->cdp_dirents, M_DEVFS2);
  149         free(cdp, M_CDEVP);
  150 }
  151 
  152 struct devfs_dirent *
  153 devfs_find(struct devfs_dirent *dd, const char *name, int namelen)
  154 {
  155         struct devfs_dirent *de;
  156 
  157         TAILQ_FOREACH(de, &dd->de_dlist, de_list) {
  158                 if (namelen != de->de_dirent->d_namlen)
  159                         continue;
  160                 if (bcmp(name, de->de_dirent->d_name, namelen) != 0)
  161                         continue;
  162                 break;
  163         }
  164         return (de);
  165 }
  166 
  167 struct devfs_dirent *
  168 devfs_newdirent(char *name, int namelen)
  169 {
  170         int i;
  171         struct devfs_dirent *de;
  172         struct dirent d;
  173 
  174         d.d_namlen = namelen;
  175         i = sizeof (*de) + GENERIC_DIRSIZ(&d); 
  176         de = malloc(i, M_DEVFS3, M_WAITOK | M_ZERO);
  177         de->de_dirent = (struct dirent *)(de + 1);
  178         de->de_dirent->d_namlen = namelen;
  179         de->de_dirent->d_reclen = GENERIC_DIRSIZ(&d);
  180         bcopy(name, de->de_dirent->d_name, namelen);
  181         de->de_dirent->d_name[namelen] = '\0';
  182         vfs_timestamp(&de->de_ctime);
  183         de->de_mtime = de->de_atime = de->de_ctime;
  184         de->de_links = 1;
  185         de->de_holdcnt = 1;
  186 #ifdef MAC
  187         mac_devfs_init(de);
  188 #endif
  189         return (de);
  190 }
  191 
  192 struct devfs_dirent *
  193 devfs_vmkdir(struct devfs_mount *dmp, char *name, int namelen, struct devfs_dirent *dotdot, u_int inode)
  194 {
  195         struct devfs_dirent *dd;
  196         struct devfs_dirent *de;
  197 
  198         /* Create the new directory */
  199         dd = devfs_newdirent(name, namelen);
  200         TAILQ_INIT(&dd->de_dlist);
  201         dd->de_dirent->d_type = DT_DIR;
  202         dd->de_mode = 0555;
  203         dd->de_links = 2;
  204         dd->de_dir = dd;
  205         if (inode != 0)
  206                 dd->de_inode = inode;
  207         else
  208                 dd->de_inode = alloc_unr(devfs_inos);
  209 
  210         /* Create the "." entry in the new directory */
  211         de = devfs_newdirent(".", 1);
  212         de->de_dirent->d_type = DT_DIR;
  213         de->de_flags |= DE_DOT;
  214         TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
  215         de->de_dir = dd;
  216 
  217         /* Create the ".." entry in the new directory */
  218         de = devfs_newdirent("..", 2);
  219         de->de_dirent->d_type = DT_DIR;
  220         de->de_flags |= DE_DOTDOT;
  221         TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
  222         if (dotdot == NULL) {
  223                 de->de_dir = dd;
  224         } else {
  225                 de->de_dir = dotdot;
  226                 TAILQ_INSERT_TAIL(&dotdot->de_dlist, dd, de_list);
  227                 dotdot->de_links++;
  228         }
  229 
  230 #ifdef MAC
  231         mac_devfs_create_directory(dmp->dm_mount, name, namelen, dd);
  232 #endif
  233         return (dd);
  234 }
  235 
  236 void
  237 devfs_dirent_free(struct devfs_dirent *de)
  238 {
  239         free(de, M_DEVFS3);
  240 }
  241 
  242 /*
  243  * The caller needs to hold the dm for the duration of the call since
  244  * dm->dm_lock may be temporary dropped.
  245  */
  246 void
  247 devfs_delete(struct devfs_mount *dm, struct devfs_dirent *de, int vp_locked)
  248 {
  249         struct vnode *vp;
  250 
  251         KASSERT((de->de_flags & DE_DOOMED) == 0,
  252                 ("devfs_delete doomed dirent"));
  253         de->de_flags |= DE_DOOMED;
  254         mtx_lock(&devfs_de_interlock);
  255         vp = de->de_vnode;
  256         if (vp != NULL) {
  257                 VI_LOCK(vp);
  258                 mtx_unlock(&devfs_de_interlock);
  259                 vholdl(vp);
  260                 sx_unlock(&dm->dm_lock);
  261                 if (!vp_locked)
  262                         vn_lock(vp, LK_EXCLUSIVE | LK_INTERLOCK | LK_RETRY);
  263                 else
  264                         VI_UNLOCK(vp);
  265                 vgone(vp);
  266                 if (!vp_locked)
  267                         VOP_UNLOCK(vp, 0);
  268                 vdrop(vp);
  269                 sx_xlock(&dm->dm_lock);
  270         } else
  271                 mtx_unlock(&devfs_de_interlock);
  272         if (de->de_symlink) {
  273                 free(de->de_symlink, M_DEVFS);
  274                 de->de_symlink = NULL;
  275         }
  276 #ifdef MAC
  277         mac_devfs_destroy(de);
  278 #endif
  279         if (de->de_inode > DEVFS_ROOTINO) {
  280                 free_unr(devfs_inos, de->de_inode);
  281                 de->de_inode = 0;
  282         }
  283         if (DEVFS_DE_DROP(de))
  284                 devfs_dirent_free(de);
  285 }
  286 
  287 /*
  288  * Called on unmount.
  289  * Recursively removes the entire tree.
  290  * The caller needs to hold the dm for the duration of the call.
  291  */
  292 
  293 static void
  294 devfs_purge(struct devfs_mount *dm, struct devfs_dirent *dd)
  295 {
  296         struct devfs_dirent *de;
  297 
  298         sx_assert(&dm->dm_lock, SX_XLOCKED);
  299         for (;;) {
  300                 de = TAILQ_FIRST(&dd->de_dlist);
  301                 if (de == NULL)
  302                         break;
  303                 TAILQ_REMOVE(&dd->de_dlist, de, de_list);
  304                 if (de->de_flags & (DE_DOT|DE_DOTDOT))
  305                         devfs_delete(dm, de, 0);
  306                 else if (de->de_dirent->d_type == DT_DIR)
  307                         devfs_purge(dm, de);
  308                 else 
  309                         devfs_delete(dm, de, 0);
  310         }
  311         devfs_delete(dm, dd, 0);
  312 }
  313 
  314 /*
  315  * Each cdev_priv has an array of pointers to devfs_dirent which is indexed
  316  * by the mount points dm_idx.
  317  * This function extends the array when necessary, taking into account that
  318  * the default array is 1 element and not malloc'ed.
  319  */
  320 static void
  321 devfs_metoo(struct cdev_priv *cdp, struct devfs_mount *dm)
  322 {
  323         struct devfs_dirent **dep;
  324         int siz;
  325 
  326         siz = (dm->dm_idx + 1) * sizeof *dep;
  327         dep = malloc(siz, M_DEVFS2, M_WAITOK | M_ZERO);
  328         dev_lock();
  329         if (dm->dm_idx <= cdp->cdp_maxdirent) {
  330                 /* We got raced */
  331                 dev_unlock();
  332                 free(dep, M_DEVFS2);
  333                 return;
  334         } 
  335         memcpy(dep, cdp->cdp_dirents, (cdp->cdp_maxdirent + 1) * sizeof *dep);
  336         if (cdp->cdp_maxdirent > 0)
  337                 free(cdp->cdp_dirents, M_DEVFS2);
  338         cdp->cdp_dirents = dep;
  339         /*
  340          * XXX: if malloc told us how much we actually got this could
  341          * XXX: be optimized.
  342          */
  343         cdp->cdp_maxdirent = dm->dm_idx;
  344         dev_unlock();
  345 }
  346 
  347 /*
  348  * The caller needs to hold the dm for the duration of the call.
  349  */
  350 static int
  351 devfs_populate_loop(struct devfs_mount *dm, int cleanup)
  352 {
  353         struct cdev_priv *cdp;
  354         struct devfs_dirent *de;
  355         struct devfs_dirent *dd;
  356         struct cdev *pdev;
  357         int j;
  358         char *q, *s;
  359 
  360         sx_assert(&dm->dm_lock, SX_XLOCKED);
  361         dev_lock();
  362         TAILQ_FOREACH(cdp, &cdevp_list, cdp_list) {
  363 
  364                 KASSERT(cdp->cdp_dirents != NULL, ("NULL cdp_dirents"));
  365 
  366                 /*
  367                  * If we are unmounting, or the device has been destroyed,
  368                  * clean up our dirent.
  369                  */
  370                 if ((cleanup || !(cdp->cdp_flags & CDP_ACTIVE)) &&
  371                     dm->dm_idx <= cdp->cdp_maxdirent &&
  372                     cdp->cdp_dirents[dm->dm_idx] != NULL) {
  373                         de = cdp->cdp_dirents[dm->dm_idx];
  374                         cdp->cdp_dirents[dm->dm_idx] = NULL;
  375                         KASSERT(cdp == de->de_cdp,
  376                             ("%s %d %s %p %p", __func__, __LINE__,
  377                             cdp->cdp_c.si_name, cdp, de->de_cdp));
  378                         KASSERT(de->de_dir != NULL, ("Null de->de_dir"));
  379                         dev_unlock();
  380 
  381                         TAILQ_REMOVE(&de->de_dir->de_dlist, de, de_list);
  382                         de->de_cdp = NULL;
  383                         de->de_inode = 0;
  384                         devfs_delete(dm, de, 0);
  385                         dev_lock();
  386                         cdp->cdp_inuse--;
  387                         dev_unlock();
  388                         return (1);
  389                 }
  390                 /*
  391                  * GC any lingering devices
  392                  */
  393                 if (!(cdp->cdp_flags & CDP_ACTIVE)) {
  394                         if (cdp->cdp_inuse > 0)
  395                                 continue;
  396                         TAILQ_REMOVE(&cdevp_list, cdp, cdp_list);
  397                         dev_unlock();
  398                         dev_rel(&cdp->cdp_c);
  399                         return (1);
  400                 }
  401                 /*
  402                  * Don't create any new dirents if we are unmounting
  403                  */
  404                 if (cleanup)
  405                         continue;
  406                 KASSERT((cdp->cdp_flags & CDP_ACTIVE), ("Bogons, I tell ya'!"));
  407 
  408                 if (dm->dm_idx <= cdp->cdp_maxdirent &&
  409                     cdp->cdp_dirents[dm->dm_idx] != NULL) {
  410                         de = cdp->cdp_dirents[dm->dm_idx];
  411                         KASSERT(cdp == de->de_cdp, ("inconsistent cdp"));
  412                         continue;
  413                 }
  414 
  415 
  416                 cdp->cdp_inuse++;
  417                 dev_unlock();
  418 
  419                 if (dm->dm_idx > cdp->cdp_maxdirent)
  420                         devfs_metoo(cdp, dm);
  421 
  422                 dd = dm->dm_rootdir;
  423                 s = cdp->cdp_c.si_name;
  424                 for (;;) {
  425                         for (q = s; *q != '/' && *q != '\0'; q++)
  426                                 continue;
  427                         if (*q != '/')
  428                                 break;
  429                         de = devfs_find(dd, s, q - s);
  430                         if (de == NULL)
  431                                 de = devfs_vmkdir(dm, s, q - s, dd, 0);
  432                         s = q + 1;
  433                         dd = de;
  434                 }
  435 
  436                 de = devfs_newdirent(s, q - s);
  437                 if (cdp->cdp_c.si_flags & SI_ALIAS) {
  438                         de->de_uid = 0;
  439                         de->de_gid = 0;
  440                         de->de_mode = 0755;
  441                         de->de_dirent->d_type = DT_LNK;
  442                         pdev = cdp->cdp_c.si_parent;
  443                         j = strlen(pdev->si_name) + 1;
  444                         de->de_symlink = malloc(j, M_DEVFS, M_WAITOK);
  445                         bcopy(pdev->si_name, de->de_symlink, j);
  446                 } else {
  447                         de->de_uid = cdp->cdp_c.si_uid;
  448                         de->de_gid = cdp->cdp_c.si_gid;
  449                         de->de_mode = cdp->cdp_c.si_mode;
  450                         de->de_dirent->d_type = DT_CHR;
  451                 }
  452                 de->de_inode = cdp->cdp_inode;
  453                 de->de_cdp = cdp;
  454 #ifdef MAC
  455                 mac_devfs_create_device(cdp->cdp_c.si_cred, dm->dm_mount,
  456                     &cdp->cdp_c, de);
  457 #endif
  458                 de->de_dir = dd;
  459                 TAILQ_INSERT_TAIL(&dd->de_dlist, de, de_list);
  460                 devfs_rules_apply(dm, de);
  461                 dev_lock();
  462                 /* XXX: could check that cdp is still active here */
  463                 KASSERT(cdp->cdp_dirents[dm->dm_idx] == NULL,
  464                     ("%s %d\n", __func__, __LINE__));
  465                 cdp->cdp_dirents[dm->dm_idx] = de;
  466                 KASSERT(de->de_cdp != (void *)0xdeadc0de,
  467                     ("%s %d\n", __func__, __LINE__));
  468                 dev_unlock();
  469                 return (1);
  470         }
  471         dev_unlock();
  472         return (0);
  473 }
  474 
  475 /*
  476  * The caller needs to hold the dm for the duration of the call.
  477  */
  478 void
  479 devfs_populate(struct devfs_mount *dm)
  480 {
  481 
  482         sx_assert(&dm->dm_lock, SX_XLOCKED);
  483         if (dm->dm_generation == devfs_generation)
  484                 return;
  485         while (devfs_populate_loop(dm, 0))
  486                 continue;
  487         dm->dm_generation = devfs_generation;
  488 }
  489 
  490 /*
  491  * The caller needs to hold the dm for the duration of the call.
  492  */
  493 void
  494 devfs_cleanup(struct devfs_mount *dm)
  495 {
  496 
  497         sx_assert(&dm->dm_lock, SX_XLOCKED);
  498         while (devfs_populate_loop(dm, 1))
  499                 continue;
  500         devfs_purge(dm, dm->dm_rootdir);
  501 }
  502 
  503 /*
  504  * devfs_create() and devfs_destroy() are called from kern_conf.c and
  505  * in both cases the devlock() mutex is held, so no further locking
  506  * is necesary and no sleeping allowed.
  507  */
  508 
  509 void
  510 devfs_create(struct cdev *dev)
  511 {
  512         struct cdev_priv *cdp;
  513 
  514         mtx_assert(&devmtx, MA_OWNED);
  515         cdp = cdev2priv(dev);
  516         cdp->cdp_flags |= CDP_ACTIVE;
  517         cdp->cdp_inode = alloc_unrl(devfs_inos);
  518         dev_refl(dev);
  519         TAILQ_INSERT_TAIL(&cdevp_list, cdp, cdp_list);
  520         devfs_generation++;
  521 }
  522 
  523 void
  524 devfs_destroy(struct cdev *dev)
  525 {
  526         struct cdev_priv *cdp;
  527 
  528         mtx_assert(&devmtx, MA_OWNED);
  529         cdp = cdev2priv(dev);
  530         cdp->cdp_flags &= ~CDP_ACTIVE;
  531         devfs_generation++;
  532 }
  533 
  534 static void
  535 devfs_devs_init(void *junk __unused)
  536 {
  537 
  538         devfs_inos = new_unrhdr(DEVFS_ROOTINO + 1, INT_MAX, &devmtx);
  539 }
  540 
  541 SYSINIT(devfs_devs, SI_SUB_DEVFS, SI_ORDER_FIRST, devfs_devs_init, NULL);
Cache object: 0d10bbf13c9e175379990fa0dd565716
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FreeBSD/Linux Kernel Cross Reference sys/fs/devfs/devfs_devs.c

FreeBSD/Linux Kernel Cross Reference
sys/fs/devfs/devfs_devs.c
