ptyfs_vfsops.c

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    1 /*      $NetBSD: ptyfs_vfsops.c,v 1.58 2020/03/16 21:20:10 pgoyette Exp $       */
    2 
    3 /*
    4  * Copyright (c) 1992, 1993, 1995
    5  *      The Regents of the University of California.  All rights reserved.
    6  *
    7  * This code is derived from software donated to Berkeley by
    8  * Jan-Simon Pendry.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 3. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  */
   35 
   36 /*
   37  * Pseudo-tty Filesystem
   38  */
   39 
   40 #include <sys/cdefs.h>
   41 __KERNEL_RCSID(0, "$NetBSD: ptyfs_vfsops.c,v 1.58 2020/03/16 21:20:10 pgoyette Exp $");
   42 
   43 #include <sys/param.h>
   44 #include <sys/systm.h>
   45 #include <sys/sysctl.h>
   46 #include <sys/conf.h>
   47 #include <sys/proc.h>
   48 #include <sys/vnode.h>
   49 #include <sys/mount.h>
   50 #include <sys/namei.h>
   51 #include <sys/stat.h>
   52 #include <sys/dirent.h>
   53 #include <sys/malloc.h>
   54 #include <sys/syslog.h>
   55 #include <sys/select.h>
   56 #include <sys/filedesc.h>
   57 #include <sys/tty.h>
   58 #include <sys/pty.h>
   59 #include <sys/kauth.h>
   60 #include <sys/module.h>
   61 
   62 #include <fs/ptyfs/ptyfs.h>
   63 #include <miscfs/genfs/genfs.h>
   64 #include <miscfs/specfs/specdev.h>
   65 
   66 MODULE(MODULE_CLASS_VFS, ptyfs, NULL);
   67 
   68 MALLOC_JUSTDEFINE(M_PTYFSMNT, "ptyfs mount", "ptyfs mount structures");
   69 MALLOC_JUSTDEFINE(M_PTYFSTMP, "ptyfs temp", "ptyfs temporary structures");
   70 
   71 VFS_PROTOS(ptyfs);
   72 
   73 static int ptyfs__allocvp(struct mount *, struct lwp *, struct vnode **,
   74     dev_t, char);
   75 static int ptyfs__makename(struct mount *, struct lwp *, char *, size_t,
   76     dev_t, char);
   77 static void ptyfs__getvattr(struct mount *, struct lwp *, struct vattr *);
   78 static int ptyfs__getmp(struct lwp *, struct mount **);
   79 
   80 /*
   81  * ptm glue: When we mount, we make ptm point to us.
   82  */
   83 struct ptm_pty *ptyfs_save_ptm;
   84 static int ptyfs_count;
   85 
   86 static TAILQ_HEAD(, ptyfsmount) ptyfs_head;
   87 
   88 struct ptm_pty ptm_ptyfspty = {
   89         ptyfs__allocvp,
   90         ptyfs__makename,
   91         ptyfs__getvattr,
   92         ptyfs__getmp,
   93 };
   94 
   95 static int
   96 ptyfs__getmp(struct lwp *l, struct mount **mpp)
   97 {
   98         struct cwdinfo *cwdi = l->l_proc->p_cwdi;
   99         struct mount *mp;
  100         struct ptyfsmount *pmnt;
  101  
  102         TAILQ_FOREACH(pmnt, &ptyfs_head, pmnt_le) {
  103                 mp = pmnt->pmnt_mp;
  104                 if (cwdi->cwdi_rdir == NULL)
  105                         goto ok;
  106 
  107                 if (vn_isunder(mp->mnt_vnodecovered, cwdi->cwdi_rdir, l))
  108                         goto ok;
  109         }
  110         *mpp = NULL;
  111         return EOPNOTSUPP;
  112 ok:
  113         *mpp = mp;
  114         return 0;
  115 }
  116 
  117 static const char *
  118 ptyfs__getpath(struct lwp *l, const struct mount *mp)
  119 {
  120 #define MAXBUF (sizeof(mp->mnt_stat.f_mntonname) + 32)
  121         struct cwdinfo *cwdi = l->l_proc->p_cwdi;
  122         char *buf;
  123         const char *rv;
  124         size_t len;
  125         char *bp;
  126         int error;
  127 
  128         rv = mp->mnt_stat.f_mntonname;
  129         if (cwdi->cwdi_rdir == NULL)
  130                 return rv;
  131 
  132         buf = malloc(MAXBUF, M_TEMP, M_WAITOK);
  133         bp = buf + MAXBUF;
  134         *--bp = '\0';
  135         error = getcwd_common(mp->mnt_vnodecovered, cwdi->cwdi_rdir, &bp,
  136             buf, MAXBUF / 2, 0, l);
  137         if (error) {    /* Mount point is out of rdir */
  138                 rv = NULL;
  139                 goto out;
  140         }
  141 
  142         len = strlen(bp);
  143         if (len < sizeof(mp->mnt_stat.f_mntonname))     /* XXX */
  144                 rv += strlen(rv) - len;
  145 out:
  146         free(buf, M_TEMP);
  147         return rv;
  148 }
  149 
  150 static int
  151 ptyfs__makename(struct mount *mp, struct lwp *l, char *tbuf, size_t bufsiz,
  152     dev_t dev, char ms)
  153 {
  154         size_t len;
  155         const char *np;
  156         int pty = minor(dev);
  157 
  158         switch (ms) {
  159         case 'p':
  160                 /* We don't provide access to the master, should we? */
  161                 len = snprintf(tbuf, bufsiz, "/dev/null");
  162                 break;
  163         case 't':
  164                 /*
  165                  * We support traditional ptys, so we can get here,
  166                  * if pty had been opened before PTYFS was mounted,
  167                  * or was opened through /dev/ptyXX devices.
  168                  * Return it only outside chroot for more security .
  169                  */
  170                 if (l->l_proc->p_cwdi->cwdi_rdir == NULL
  171                     && ptyfs_save_ptm != NULL 
  172                     && ptyfs_next_active(mp, pty) != pty)
  173                         return (*ptyfs_save_ptm->makename)(mp, l,
  174                             tbuf, bufsiz, dev, ms);
  175 
  176                 np = ptyfs__getpath(l, mp);
  177                 if (np == NULL)
  178                         return EOPNOTSUPP;
  179                 len = snprintf(tbuf, bufsiz, "%s/%llu", np,
  180                         (unsigned long long)minor(dev));
  181                 break;
  182         default:
  183                 return EINVAL;
  184         }
  185 
  186         return len >= bufsiz ? ENOSPC : 0;
  187 }
  188 
  189 
  190 static int
  191 /*ARGSUSED*/
  192 ptyfs__allocvp(struct mount *mp, struct lwp *l, struct vnode **vpp,
  193     dev_t dev, char ms)
  194 {
  195         int error;
  196         ptyfstype type;
  197 
  198         switch (ms) {
  199         case 'p':
  200                 type = PTYFSptc;
  201                 break;
  202         case 't':
  203                 type = PTYFSpts;
  204                 break;
  205         default:
  206                 return EINVAL;
  207         }
  208 
  209         error = ptyfs_allocvp(mp, vpp, type, minor(dev));
  210         if (error)
  211                 return error;
  212         error = vn_lock(*vpp, LK_EXCLUSIVE);
  213         if (error) {
  214                 vrele(*vpp);
  215                 *vpp = NULL;
  216                 return error;
  217         }
  218         if (type == PTYFSptc)
  219                 ptyfs_set_active(mp, minor(dev));
  220         return 0;
  221 }
  222 
  223 
  224 static void
  225 ptyfs__getvattr(struct mount *mp, struct lwp *l, struct vattr *vattr)
  226 {
  227         struct ptyfsmount *pmnt = VFSTOPTY(mp);
  228         vattr_null(vattr);
  229         /* get real uid */
  230         vattr->va_uid = kauth_cred_getuid(l->l_cred);
  231         vattr->va_gid = pmnt->pmnt_gid;
  232         vattr->va_mode = pmnt->pmnt_mode;
  233 }
  234 
  235 
  236 void
  237 ptyfs_init(void)
  238 {
  239 
  240         TAILQ_INIT(&ptyfs_head);
  241         malloc_type_attach(M_PTYFSMNT);
  242         malloc_type_attach(M_PTYFSTMP);
  243         ptyfs_hashinit();
  244 }
  245 
  246 void
  247 ptyfs_reinit(void)
  248 {
  249 
  250 }
  251 
  252 void
  253 ptyfs_done(void)
  254 {
  255 
  256         ptyfs_hashdone();
  257         malloc_type_detach(M_PTYFSTMP);
  258         malloc_type_detach(M_PTYFSMNT);
  259 }
  260 
  261 #define OSIZE sizeof(struct { int f; gid_t g; mode_t m; })
  262 /*
  263  * Mount the Pseudo tty params filesystem
  264  */
  265 int
  266 ptyfs_mount(struct mount *mp, const char *path, void *data, size_t *data_len)
  267 {
  268         struct lwp *l = curlwp;
  269         int error = 0;
  270         struct ptyfsmount *pmnt;
  271         struct ptyfs_args *args = data;
  272 
  273         if (args == NULL)
  274                 return EINVAL;
  275         if (*data_len != sizeof *args) {
  276                 if (*data_len != OSIZE || args->version >= PTYFS_ARGSVERSION)
  277                         return EINVAL;
  278         }
  279 
  280         if (UIO_MX & (UIO_MX - 1)) {
  281                 log(LOG_ERR, "ptyfs: invalid directory entry size");
  282                 return EINVAL;
  283         }
  284 
  285         if (mp->mnt_flag & MNT_GETARGS) {
  286                 pmnt = VFSTOPTY(mp);
  287                 if (pmnt == NULL)
  288                         return EIO;
  289                 args->mode = pmnt->pmnt_mode;
  290                 args->gid = pmnt->pmnt_gid;
  291                 if (args->version >= PTYFS_ARGSVERSION) {
  292                         args->flags = pmnt->pmnt_flags;
  293                         *data_len = sizeof *args;
  294                 } else {
  295                         *data_len = OSIZE;
  296                 }
  297                 return 0;
  298         }
  299 
  300 #if 0
  301         /* Don't allow more than one mount */
  302         if (ptyfs_count)
  303                 return EBUSY;
  304 #endif
  305 
  306         if (mp->mnt_flag & MNT_UPDATE)
  307                 return EOPNOTSUPP;
  308 
  309         if (args->version > PTYFS_ARGSVERSION)
  310                 return EINVAL;
  311 
  312         pmnt = malloc(sizeof(struct ptyfsmount), M_PTYFSMNT, M_WAITOK);
  313 
  314         mp->mnt_data = pmnt;
  315         mutex_init(&pmnt->pmnt_lock, MUTEX_DEFAULT, IPL_NONE);
  316         pmnt->pmnt_gid = args->gid;
  317         pmnt->pmnt_mode = args->mode;
  318         if (args->version >= PTYFS_ARGSVERSION)
  319                 pmnt->pmnt_flags = args->flags;
  320         else
  321                 pmnt->pmnt_flags = 0;
  322         pmnt->pmnt_bitmap_size = 0;
  323         pmnt->pmnt_bitmap = NULL;
  324         mp->mnt_flag |= MNT_LOCAL;
  325         vfs_getnewfsid(mp);
  326 
  327         if ((error = set_statvfs_info(path, UIO_USERSPACE, "ptyfs",
  328             UIO_SYSSPACE, mp->mnt_op->vfs_name, mp, l)) != 0) {
  329                 free(pmnt, M_PTYFSMNT);
  330                 return error;
  331         }
  332 
  333         pmnt->pmnt_mp = mp;
  334         TAILQ_INSERT_TAIL(&ptyfs_head, pmnt, pmnt_le);
  335         if (ptyfs_count++ == 0) {
  336                 /* Point pty access to us */
  337                 ptyfs_save_ptm = pty_sethandler(&ptm_ptyfspty);
  338         }
  339         return 0;
  340 }
  341 
  342 /*ARGSUSED*/
  343 int
  344 ptyfs_start(struct mount *mp, int flags)
  345 {
  346         return 0;
  347 }
  348 
  349 /*ARGSUSED*/
  350 int
  351 ptyfs_unmount(struct mount *mp, int mntflags)
  352 {
  353         int error;
  354         int flags = 0;
  355         struct ptyfsmount *pmnt;
  356 
  357         if (mntflags & MNT_FORCE)
  358                 flags |= FORCECLOSE;
  359 
  360         if ((error = vflush(mp, 0, flags)) != 0)
  361                 return error;
  362 
  363         ptyfs_count--;
  364         if (ptyfs_count == 0) {
  365                 /* Restore where pty access was pointing */
  366                 (void)pty_sethandler(ptyfs_save_ptm);
  367                 ptyfs_save_ptm = NULL;
  368         }
  369         TAILQ_FOREACH(pmnt, &ptyfs_head, pmnt_le) {
  370                 if (pmnt->pmnt_mp == mp) {
  371                         TAILQ_REMOVE(&ptyfs_head, pmnt, pmnt_le);
  372                         break;
  373                 }
  374         }
  375 
  376         /*
  377          * Finally, throw away the ptyfsmount structure
  378          */
  379         if (pmnt->pmnt_bitmap_size > 0)
  380                 kmem_free(pmnt->pmnt_bitmap, pmnt->pmnt_bitmap_size);
  381         mutex_destroy(&pmnt->pmnt_lock);
  382         free(mp->mnt_data, M_PTYFSMNT);
  383         mp->mnt_data = NULL;
  384 
  385         return 0;
  386 }
  387 
  388 int
  389 ptyfs_root(struct mount *mp, int lktype, struct vnode **vpp)
  390 {
  391         int error;
  392 
  393         /* setup "." */
  394         error = ptyfs_allocvp(mp, vpp, PTYFSroot, 0);
  395         if (error)
  396                 return error;
  397         error = vn_lock(*vpp, lktype);
  398         if (error) {
  399                 vrele(*vpp);
  400                 *vpp = NULL;
  401                 return error;
  402         }
  403         return 0;
  404 }
  405 
  406 /*ARGSUSED*/
  407 int
  408 ptyfs_sync(struct mount *mp, int waitfor,
  409     kauth_cred_t uc)
  410 {
  411         return 0;
  412 }
  413 
  414 /*
  415  * Initialize this vnode / ptynode pair.
  416  * Only for the slave side of a pty, caller assures
  417  * no other thread will try to load this node.
  418  */
  419 int
  420 ptyfs_loadvnode(struct mount *mp, struct vnode *vp,
  421     const void *key, size_t key_len, const void **new_key)
  422 {
  423         struct ptyfskey pkey;
  424         struct ptyfsnode *ptyfs;
  425 
  426         KASSERT(key_len == sizeof(pkey));
  427         memcpy(&pkey, key, key_len);
  428 
  429         ptyfs = ptyfs_get_node(pkey.ptk_type, pkey.ptk_pty);
  430         KASSERT(memcmp(&ptyfs->ptyfs_key, &pkey, sizeof(pkey)) == 0);
  431 
  432         switch (pkey.ptk_type) {
  433         case PTYFSroot: /* /pts = dr-xr-xr-x */
  434                 vp->v_type = VDIR;
  435                 vp->v_vflag = VV_ROOT;
  436                 break;
  437 
  438         case PTYFSpts:  /* /pts/N = cxxxxxxxxx */
  439         case PTYFSptc:  /* controlling side = cxxxxxxxxx */
  440                 vp->v_type = VCHR;
  441                 spec_node_init(vp, PTYFS_MAKEDEV(ptyfs));
  442                 break;
  443         default:
  444                 panic("ptyfs_loadvnode");
  445         }
  446 
  447         vp->v_tag = VT_PTYFS;
  448         vp->v_op = ptyfs_vnodeop_p;
  449         vp->v_data = ptyfs;
  450         uvm_vnp_setsize(vp, 0);
  451         *new_key = &ptyfs->ptyfs_key;
  452         return 0;
  453 }
  454 
  455 /*
  456  * Kernfs flat namespace lookup.
  457  * Currently unsupported.
  458  */
  459 /*ARGSUSED*/
  460 int
  461 ptyfs_vget(struct mount *mp, ino_t ino, int lktype,
  462     struct vnode **vpp)
  463 {
  464         return EOPNOTSUPP;
  465 }
  466 
  467 extern const struct vnodeopv_desc ptyfs_vnodeop_opv_desc;
  468 
  469 const struct vnodeopv_desc * const ptyfs_vnodeopv_descs[] = {
  470         &ptyfs_vnodeop_opv_desc,
  471         NULL,
  472 };
  473 
  474 struct vfsops ptyfs_vfsops = {
  475         .vfs_name = MOUNT_PTYFS,
  476         .vfs_min_mount_data = sizeof (struct ptyfs_args),
  477         .vfs_mount = ptyfs_mount,
  478         .vfs_start = ptyfs_start,
  479         .vfs_unmount = ptyfs_unmount,
  480         .vfs_root = ptyfs_root,
  481         .vfs_quotactl = (void *)eopnotsupp,
  482         .vfs_statvfs = genfs_statvfs,
  483         .vfs_sync = ptyfs_sync,
  484         .vfs_vget = ptyfs_vget,
  485         .vfs_loadvnode = ptyfs_loadvnode,
  486         .vfs_fhtovp = (void *)eopnotsupp,
  487         .vfs_vptofh = (void *)eopnotsupp,
  488         .vfs_init = ptyfs_init,
  489         .vfs_reinit = ptyfs_reinit,
  490         .vfs_done = ptyfs_done,
  491         .vfs_snapshot = (void *)eopnotsupp,
  492         .vfs_extattrctl = (void *)eopnotsupp,
  493         .vfs_suspendctl = genfs_suspendctl,
  494         .vfs_renamelock_enter = genfs_renamelock_enter,
  495         .vfs_renamelock_exit = genfs_renamelock_exit,
  496         .vfs_fsync = (void *)eopnotsupp,
  497         .vfs_opv_descs = ptyfs_vnodeopv_descs
  498 };
  499 
  500 SYSCTL_SETUP(ptyfs_sysctl_setup, "ptyfs sysctl")
  501 {
  502 
  503         sysctl_createv(clog, 0, NULL, NULL,
  504                        CTLFLAG_PERMANENT,
  505                        CTLTYPE_NODE, "ptyfs",
  506                        SYSCTL_DESCR("Pty file system"),
  507                        NULL, 0, NULL, 0,
  508                        CTL_VFS, 23, CTL_EOL);
  509         /*
  510          * XXX the "23" above could be dynamic, thereby eliminating
  511          * one more instance of the "number to vfs" mapping problem,
  512          * but "23" is the order as taken from sys/mount.h
  513          */
  514 }
  515 
  516 static int
  517 ptyfs_modcmd(modcmd_t cmd, void *arg)
  518 {
  519         int error;
  520 
  521         switch (cmd) {
  522         case MODULE_CMD_INIT:
  523                 error = vfs_attach(&ptyfs_vfsops);
  524                 if (error != 0)
  525                         break;
  526                 break;
  527         case MODULE_CMD_FINI:
  528                 error = vfs_detach(&ptyfs_vfsops);
  529                 if (error != 0)
  530                         break;
  531                 break;
  532         default:
  533                 error = ENOTTY;
  534                 break;
  535         }
  536 
  537         return (error);
  538 }
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FreeBSD/Linux Kernel Cross Reference sys/fs/ptyfs/ptyfs_vfsops.c

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sys/fs/ptyfs/ptyfs_vfsops.c
