Ejemplo n.º 1
0
/*
 * Mount a file descriptor onto the node in the file system.
 * Create a new vnode, update the attributes with info from the
 * file descriptor and the mount point.  The mask, mode, uid, gid,
 * atime, mtime and ctime are taken from the mountpt.  Link count is
 * set to one, the file system id is namedev and nodeid is unique
 * for each mounted object.  Other attributes are taken from mount point.
 * Make sure user is owner (or root) with write permissions on mount point.
 * Hash the new vnode and return 0.
 * Upon entry to this routine, the file descriptor is in the
 * fd field of a struct namefd.  Copy that structure from user
 * space and retrieve the file descriptor.
 */
static int
nm_mount(vfs_t *vfsp, vnode_t *mvp, struct mounta *uap, cred_t *crp)
{
	struct namefd namefdp;
	struct vnode *filevp;		/* file descriptor vnode */
	struct file *fp;
	struct vnode *newvp;		/* vnode representing this mount */
	struct vnode *rvp;		/* realvp (if any) for the mountpt */
	struct namenode *nodep;		/* namenode for this mount */
	struct vattr filevattr;		/* attributes of file dec.  */
	struct vattr *vattrp;		/* attributes of this mount */
	char *resource_name;
	char *resource_nodetype;
	statvfs64_t *svfsp;
	int error = 0;

	/*
	 * Get the file descriptor from user space.
	 * Make sure the file descriptor is valid and has an
	 * associated file pointer.
	 * If so, extract the vnode from the file pointer.
	 */
	if (uap->datalen != sizeof (struct namefd))
		return (EINVAL);

	if (copyin(uap->dataptr, &namefdp, uap->datalen))
		return (EFAULT);

	if ((fp = getf(namefdp.fd)) == NULL)
		return (EBADF);

	/*
	 * If the mount point already has something mounted
	 * on it, disallow this mount.  (This restriction may
	 * be removed in a later release).
	 * Or unmount has completed but the namefs ROOT vnode
	 * count has not decremented to zero, disallow this mount.
	 */

	mutex_enter(&mvp->v_lock);
	if ((mvp->v_flag & VROOT) ||
	    vfs_matchops(mvp->v_vfsp, namefs_vfsops)) {
		mutex_exit(&mvp->v_lock);
		releasef(namefdp.fd);
		return (EBUSY);
	}
	mutex_exit(&mvp->v_lock);

	/*
	 * Cannot allow users to fattach() in /dev/pts.
	 * First, there is no need for doing so and secondly
	 * we cannot allow arbitrary users to park on a node in
	 * /dev/pts or /dev/vt.
	 */
	rvp = NULLVP;
	if (vn_matchops(mvp, spec_getvnodeops()) &&
	    VOP_REALVP(mvp, &rvp, NULL) == 0 && rvp &&
	    (vn_matchops(rvp, devpts_getvnodeops()) ||
	    vn_matchops(rvp, devvt_getvnodeops()))) {
		releasef(namefdp.fd);
		return (ENOTSUP);
	}

	filevp = fp->f_vnode;
	if (filevp->v_type == VDIR || filevp->v_type == VPORT) {
		releasef(namefdp.fd);
		return (EINVAL);
	}

	/*
	 * If the fd being mounted refers to neither a door nor a stream,
	 * make sure the caller is privileged.
	 */
	if (filevp->v_type != VDOOR && filevp->v_stream == NULL) {
		if (secpolicy_fs_mount(crp, filevp, vfsp) != 0) {
			/* fd is neither a stream nor a door */
			releasef(namefdp.fd);
			return (EINVAL);
		}
	}

	/*
	 * Make sure the file descriptor is not the root of some
	 * file system.
	 * If it's not, create a reference and allocate a namenode
	 * to represent this mount request.
	 */
	if (filevp->v_flag & VROOT) {
		releasef(namefdp.fd);
		return (EBUSY);
	}

	nodep = kmem_zalloc(sizeof (struct namenode), KM_SLEEP);

	mutex_init(&nodep->nm_lock, NULL, MUTEX_DEFAULT, NULL);
	vattrp = &nodep->nm_vattr;
	vattrp->va_mask = AT_ALL;
	if (error = VOP_GETATTR(mvp, vattrp, 0, crp, NULL))
		goto out;

	filevattr.va_mask = AT_ALL;
	if (error = VOP_GETATTR(filevp, &filevattr, 0, crp, NULL))
		goto out;
	/*
	 * Make sure the user is the owner of the mount point
	 * or has sufficient privileges.
	 */
	if (error = secpolicy_vnode_owner(crp, vattrp->va_uid))
		goto out;

	/*
	 * Make sure the user has write permissions on the
	 * mount point (or has sufficient privileges).
	 */
	if (!(vattrp->va_mode & VWRITE) &&
	    secpolicy_vnode_access(crp, mvp, vattrp->va_uid, VWRITE) != 0) {
		error = EACCES;
		goto out;
	}

	/*
	 * If the file descriptor has file/record locking, don't
	 * allow the mount to succeed.
	 */
	if (vn_has_flocks(filevp)) {
		error = EACCES;
		goto out;
	}

	/*
	 * Initialize the namenode.
	 */
	if (filevp->v_stream) {
		struct stdata *stp = filevp->v_stream;
		mutex_enter(&stp->sd_lock);
		stp->sd_flag |= STRMOUNT;
		mutex_exit(&stp->sd_lock);
	}
	nodep->nm_filevp = filevp;
	mutex_enter(&fp->f_tlock);
	fp->f_count++;
	mutex_exit(&fp->f_tlock);

	releasef(namefdp.fd);
	nodep->nm_filep = fp;
	nodep->nm_mountpt = mvp;

	/*
	 * The attributes for the mounted file descriptor were initialized
	 * above by applying VOP_GETATTR to the mount point.  Some of
	 * the fields of the attributes structure will be overwritten
	 * by the attributes from the file descriptor.
	 */
	vattrp->va_type    = filevattr.va_type;
	vattrp->va_fsid    = namedev;
	vattrp->va_nodeid  = namenodeno_alloc();
	vattrp->va_nlink   = 1;
	vattrp->va_size    = filevattr.va_size;
	vattrp->va_rdev    = filevattr.va_rdev;
	vattrp->va_blksize = filevattr.va_blksize;
	vattrp->va_nblocks = filevattr.va_nblocks;
	vattrp->va_seq	   = 0;

	/*
	 * Initialize new vnode structure for the mounted file descriptor.
	 */
	nodep->nm_vnode = vn_alloc(KM_SLEEP);
	newvp = NMTOV(nodep);

	newvp->v_flag = filevp->v_flag | VROOT | VNOMAP | VNOSWAP;
	vn_setops(newvp, nm_vnodeops);
	newvp->v_vfsp = vfsp;
	newvp->v_stream = filevp->v_stream;
	newvp->v_type = filevp->v_type;
	newvp->v_rdev = filevp->v_rdev;
	newvp->v_data = (caddr_t)nodep;
	VFS_HOLD(vfsp);
	vn_exists(newvp);

	/*
	 * Initialize the vfs structure.
	 */
	vfsp->vfs_vnodecovered = NULL;
	vfsp->vfs_flag |= VFS_UNLINKABLE;
	vfsp->vfs_bsize = 1024;
	vfsp->vfs_fstype = namefstype;
	vfs_make_fsid(&vfsp->vfs_fsid, namedev, namefstype);
	vfsp->vfs_data = (caddr_t)nodep;
	vfsp->vfs_dev = namedev;
	vfsp->vfs_bcount = 0;

	/*
	 * Set the name we mounted from.
	 */
	switch (filevp->v_type) {
	case VPROC:	/* VOP_GETATTR() translates this to VREG */
	case VREG:	resource_nodetype = "file"; break;
	case VDIR:	resource_nodetype = "directory"; break;
	case VBLK:	resource_nodetype = "device"; break;
	case VCHR:	resource_nodetype = "device"; break;
	case VLNK:	resource_nodetype = "link"; break;
	case VFIFO:	resource_nodetype = "fifo"; break;
	case VDOOR:	resource_nodetype = "door"; break;
	case VSOCK:	resource_nodetype = "socket"; break;
	default:	resource_nodetype = "resource"; break;
	}

#define	RESOURCE_NAME_SZ 128 /* Maximum length of the resource name */
	resource_name = kmem_alloc(RESOURCE_NAME_SZ, KM_SLEEP);
	svfsp = kmem_alloc(sizeof (statvfs64_t), KM_SLEEP);

	error = VFS_STATVFS(filevp->v_vfsp, svfsp);
	if (error == 0) {
		(void) snprintf(resource_name, RESOURCE_NAME_SZ,
		    "unspecified_%s_%s", svfsp->f_basetype, resource_nodetype);
	} else {
		(void) snprintf(resource_name, RESOURCE_NAME_SZ,
		    "unspecified_%s", resource_nodetype);
	}

	vfs_setresource(vfsp, resource_name);

	kmem_free(svfsp, sizeof (statvfs64_t));
	kmem_free(resource_name, RESOURCE_NAME_SZ);
#undef RESOURCE_NAME_SZ

	/*
	 * Insert the namenode.
	 */
	mutex_enter(&ntable_lock);
	nameinsert(nodep);
	mutex_exit(&ntable_lock);
	return (0);
out:
	releasef(namefdp.fd);
	kmem_free(nodep, sizeof (struct namenode));
	return (error);
}
Ejemplo n.º 2
0
/*
 * Create a reference to the vnode representing the file descriptor.
 * Then, apply the VOP_OPEN operation to that vnode.
 *
 * The vnode for the file descriptor may be switched under you.
 * If it is, search the hash list for an nodep - nodep->nm_filevp
 * pair. If it exists, return that nodep to the user.
 * If it does not exist, create a new namenode to attach
 * to the nodep->nm_filevp then place the pair on the hash list.
 *
 * Newly created objects are like children/nodes in the mounted
 * file system, with the parent being the initial mount.
 */
int
nm_open(vnode_t **vpp, int flag, cred_t *crp, caller_context_t *ct)
{
	struct namenode *nodep = VTONM(*vpp);
	int error = 0;
	struct namenode *newnamep;
	struct vnode *newvp;
	struct vnode *infilevp;
	struct vnode *outfilevp;

	/*
	 * If the vnode is switched under us, the corresponding
	 * VN_RELE for this VN_HOLD will be done by the file system
	 * performing the switch. Otherwise, the corresponding
	 * VN_RELE will be done by nm_close().
	 */
	infilevp = outfilevp = nodep->nm_filevp;
	VN_HOLD(outfilevp);

	if ((error = VOP_OPEN(&outfilevp, flag, crp, ct)) != 0) {
		VN_RELE(outfilevp);
		return (error);
	}
	if (infilevp != outfilevp) {
		/*
		 * See if the new filevp (outfilevp) is already associated
		 * with the mount point. If it is, then it already has a
		 * namenode associated with it.
		 */
		mutex_enter(&ntable_lock);
		if ((newnamep =
		    namefind(outfilevp, nodep->nm_mountpt)) != NULL) {
			struct vnode *vp = NMTOV(newnamep);

			VN_HOLD(vp);
			goto gotit;
		}

		newnamep = kmem_zalloc(sizeof (struct namenode), KM_SLEEP);
		newvp = vn_alloc(KM_SLEEP);
		newnamep->nm_vnode = newvp;

		mutex_init(&newnamep->nm_lock, NULL, MUTEX_DEFAULT, NULL);

		mutex_enter(&nodep->nm_lock);
		newvp->v_flag = ((*vpp)->v_flag | VNOMAP | VNOSWAP) & ~VROOT;
		vn_setops(newvp, vn_getops(*vpp));
		newvp->v_vfsp = &namevfs;
		newvp->v_stream = outfilevp->v_stream;
		newvp->v_type = outfilevp->v_type;
		newvp->v_rdev = outfilevp->v_rdev;
		newvp->v_data = (caddr_t)newnamep;
		vn_exists(newvp);
		bcopy(&nodep->nm_vattr, &newnamep->nm_vattr, sizeof (vattr_t));
		newnamep->nm_vattr.va_type = outfilevp->v_type;
		newnamep->nm_vattr.va_nodeid = namenodeno_alloc();
		newnamep->nm_vattr.va_size = (u_offset_t)0;
		newnamep->nm_vattr.va_rdev = outfilevp->v_rdev;
		newnamep->nm_flag = NMNMNT;
		newnamep->nm_filevp = outfilevp;
		newnamep->nm_filep = nodep->nm_filep;
		newnamep->nm_mountpt = nodep->nm_mountpt;
		mutex_exit(&nodep->nm_lock);

		/*
		 * Insert the new namenode into the hash list.
		 */
		nameinsert(newnamep);
gotit:
		mutex_exit(&ntable_lock);
		/*
		 * Release the above reference to the infilevp, the reference
		 * to the NAMEFS vnode, create a reference to the new vnode
		 * and return the new vnode to the user.
		 */
		VN_RELE(*vpp);
		*vpp = NMTOV(newnamep);
	}
	return (0);
}