1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 /* 22 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26 #pragma ident "%Z%%M% %I% %E% SMI" 27 28 #include <sys/types.h> 29 #include <sys/param.h> 30 #include <sys/cmn_err.h> 31 #include <sys/cred.h> 32 #include <sys/debug.h> 33 #include <sys/errno.h> 34 #include <sys/proc.h> 35 #include <sys/procfs.h> 36 #include <sys/stat.h> 37 #include <sys/statvfs.h> 38 #include <sys/sysmacros.h> 39 #include <sys/systm.h> 40 #include <sys/var.h> 41 #include <sys/vfs.h> 42 #include <sys/vfs_opreg.h> 43 #include <sys/vnode.h> 44 #include <sys/mode.h> 45 #include <sys/signal.h> 46 #include <sys/user.h> 47 #include <sys/mount.h> 48 #include <sys/bitmap.h> 49 #include <sys/kmem.h> 50 #include <sys/policy.h> 51 #include <fs/fs_subr.h> 52 #include <sys/fs/mntdata.h> 53 #include <sys/zone.h> 54 55 /* 56 * This is the loadable module wrapper. 57 */ 58 #include <sys/modctl.h> 59 60 static int mntinit(int, char *); 61 62 static mntopts_t mnt_mntopts = { 63 0, 64 NULL 65 }; 66 67 static vfsdef_t vfw = { 68 VFSDEF_VERSION, 69 "mntfs", 70 mntinit, 71 VSW_HASPROTO|VSW_STATS, 72 &mnt_mntopts 73 }; 74 75 /* 76 * Module linkage information for the kernel. 77 */ 78 extern struct mod_ops mod_fsops; 79 80 static struct modlfs modlfs = { 81 &mod_fsops, "mount information file system", &vfw 82 }; 83 84 static struct modlinkage modlinkage = { 85 MODREV_1, (void *)&modlfs, NULL 86 }; 87 88 int 89 _init(void) 90 { 91 return (mod_install(&modlinkage)); 92 } 93 94 int 95 _info(struct modinfo *modinfop) 96 { 97 return (mod_info(&modlinkage, modinfop)); 98 } 99 100 /* 101 * N.B. 102 * No _fini routine. The module cannot be unloaded once loaded. 103 * The NO_UNLOAD_STUB in modstubs.s must change if this module 104 * is ever modified to become unloadable. 105 */ 106 107 static int mntfstype; 108 static major_t mnt_major; 109 static minor_t mnt_minor; 110 static kmutex_t mnt_minor_lock; 111 112 /* 113 * /mnttab VFS operations vector. 114 */ 115 static int mntmount(), mntunmount(), mntroot(), mntstatvfs(); 116 117 static void 118 mntinitrootnode(mntnode_t *mnp) 119 { 120 struct vnode *vp; 121 122 bzero((caddr_t)mnp, sizeof (*mnp)); 123 124 mnp->mnt_vnode = vn_alloc(KM_SLEEP); 125 126 vp = MTOV(mnp); 127 128 vp->v_flag = VROOT|VNOCACHE|VNOMAP|VNOSWAP|VNOMOUNT; 129 vn_setops(vp, mntvnodeops); 130 vp->v_type = VREG; 131 vp->v_data = (caddr_t)mnp; 132 } 133 134 static int 135 mntinit(int fstype, char *name) 136 { 137 static const fs_operation_def_t mnt_vfsops_template[] = { 138 VFSNAME_MOUNT, { .vfs_mount = mntmount }, 139 VFSNAME_UNMOUNT, { .vfs_unmount = mntunmount }, 140 VFSNAME_ROOT, { .vfs_root = mntroot }, 141 VFSNAME_STATVFS, { .vfs_statvfs = mntstatvfs }, 142 NULL, NULL 143 }; 144 extern const fs_operation_def_t mnt_vnodeops_template[]; 145 int error; 146 147 mntfstype = fstype; 148 ASSERT(mntfstype != 0); 149 /* 150 * Associate VFS ops vector with this fstype. 151 */ 152 error = vfs_setfsops(fstype, mnt_vfsops_template, NULL); 153 if (error != 0) { 154 cmn_err(CE_WARN, "mntinit: bad vfs ops template"); 155 return (error); 156 } 157 158 /* Vnode ops too. */ 159 160 error = vn_make_ops(name, mnt_vnodeops_template, &mntvnodeops); 161 if (error != 0) { 162 (void) vfs_freevfsops_by_type(fstype); 163 cmn_err(CE_WARN, "mntinit: bad vnode ops template"); 164 return (error); 165 } 166 167 /* 168 * Assign a unique "device" number (used by stat(2)). 169 */ 170 if ((mnt_major = getudev()) == (major_t)-1) { 171 cmn_err(CE_WARN, "mntinit: can't get unique device number"); 172 mnt_major = 0; 173 } 174 mutex_init(&mnt_minor_lock, NULL, MUTEX_DEFAULT, NULL); 175 176 return (0); 177 } 178 179 /* ARGSUSED */ 180 static int 181 mntmount(struct vfs *vfsp, struct vnode *mvp, 182 struct mounta *uap, struct cred *cr) 183 { 184 mntdata_t *mnt; 185 mntnode_t *mnp; 186 zone_t *zone = curproc->p_zone; 187 188 if (secpolicy_fs_mount(cr, mvp, vfsp) != 0) 189 return (EPERM); 190 191 /* 192 * You can only mount mnttab in your current zone. 193 */ 194 if (zone == global_zone) { 195 zone_t *mntzone; 196 197 mntzone = zone_find_by_path(refstr_value(vfsp->vfs_mntpt)); 198 ASSERT(mntzone != NULL); 199 zone_rele(mntzone); 200 if (mntzone != zone) 201 return (EBUSY); 202 } 203 204 /* 205 * Having the resource be anything but "mnttab" doesn't make sense 206 */ 207 vfs_setresource(vfsp, "mnttab"); 208 209 mnt = kmem_alloc(sizeof (*mnt), KM_SLEEP); 210 mutex_enter(&mvp->v_lock); 211 if ((uap->flags & MS_OVERLAY) == 0 && 212 (mvp->v_count > 1 || (mvp->v_flag & VROOT))) { 213 mutex_exit(&mvp->v_lock); 214 kmem_free(mnt, sizeof (*mnt)); 215 return (EBUSY); 216 } 217 mutex_exit(&mvp->v_lock); 218 219 mnt->mnt_nopen = 0; 220 mnt->mnt_size = 0; 221 zone_hold(mnt->mnt_zone = zone); 222 mnp = &mnt->mnt_node; 223 224 vfsp->vfs_fstype = mntfstype; 225 vfsp->vfs_data = (caddr_t)mnt; 226 /* 227 * find an available minor device number for this mount. 228 */ 229 mutex_enter(&mnt_minor_lock); 230 do { 231 mnt_minor = (mnt_minor + 1) & L_MAXMIN32; 232 vfsp->vfs_dev = makedevice(mnt_major, mnt_minor); 233 } while (vfs_devismounted(vfsp->vfs_dev)); 234 mutex_exit(&mnt_minor_lock); 235 vfs_make_fsid(&vfsp->vfs_fsid, vfsp->vfs_dev, mntfstype); 236 vfsp->vfs_bsize = DEV_BSIZE; 237 mntinitrootnode(mnp); 238 MTOV(mnp)->v_vfsp = vfsp; 239 mnp->mnt_mountvp = mvp; 240 vn_exists(MTOV(mnp)); 241 return (0); 242 } 243 244 /* ARGSUSED */ 245 static int 246 mntunmount(struct vfs *vfsp, int flag, struct cred *cr) 247 { 248 mntdata_t *mnt = (mntdata_t *)vfsp->vfs_data; 249 vnode_t *vp = MTOV(&mnt->mnt_node); 250 251 if (secpolicy_fs_unmount(cr, vfsp) != 0) 252 return (EPERM); 253 254 /* 255 * Ensure that no /mnttab vnodes are in use on this mount point. 256 */ 257 mutex_enter(&vp->v_lock); 258 if (vp->v_count > 1 || mnt->mnt_nopen > 0) { 259 mutex_exit(&vp->v_lock); 260 return (EBUSY); 261 } 262 263 mutex_exit(&vp->v_lock); 264 zone_rele(mnt->mnt_zone); 265 vn_invalid(vp); 266 vn_free(vp); 267 kmem_free(mnt, sizeof (*mnt)); 268 return (0); 269 } 270 271 /* ARGSUSED */ 272 static int 273 mntroot(struct vfs *vfsp, struct vnode **vpp) 274 { 275 mntnode_t *mnp = &((mntdata_t *)vfsp->vfs_data)->mnt_node; 276 struct vnode *vp = MTOV(mnp); 277 278 VN_HOLD(vp); 279 *vpp = vp; 280 return (0); 281 } 282 283 static int 284 mntstatvfs(struct vfs *vfsp, struct statvfs64 *sp) 285 { 286 dev32_t d32; 287 288 bzero((caddr_t)sp, sizeof (*sp)); 289 sp->f_bsize = DEV_BSIZE; 290 sp->f_frsize = DEV_BSIZE; 291 sp->f_blocks = (fsblkcnt64_t)0; 292 sp->f_bfree = (fsblkcnt64_t)0; 293 sp->f_bavail = (fsblkcnt64_t)0; 294 sp->f_files = (fsfilcnt64_t)1; 295 sp->f_ffree = (fsfilcnt64_t)0; 296 sp->f_favail = (fsfilcnt64_t)0; 297 (void) cmpldev(&d32, vfsp->vfs_dev); 298 sp->f_fsid = d32; 299 (void) strcpy(sp->f_basetype, vfssw[mntfstype].vsw_name); 300 sp->f_flag = vf_to_stf(vfsp->vfs_flag); 301 sp->f_namemax = 64; /* quite arbitrary */ 302 bzero(sp->f_fstr, sizeof (sp->f_fstr)); 303 (void) strcpy(sp->f_fstr, "/mnttab"); 304 (void) strcpy(&sp->f_fstr[8], "/mnttab"); 305 return (0); 306 } 307