1 /*- 2 * Copyright (c) 2012 The FreeBSD Foundation 3 * All rights reserved. 4 * 5 * This software was developed by Edward Tomasz Napierala under sponsorship 6 * from the FreeBSD Foundation. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * $FreeBSD$ 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include <sys/param.h> 36 #include <sys/systm.h> 37 #include <sys/buf.h> 38 #include <sys/ioccom.h> 39 #include <sys/mount.h> 40 #include <sys/vnode.h> 41 #include <sys/conf.h> 42 #include <sys/jail.h> 43 #include <sys/sx.h> 44 45 #include <security/mac/mac_framework.h> 46 47 #include <ufs/ufs/extattr.h> 48 #include <ufs/ufs/quota.h> 49 #include <ufs/ufs/ufsmount.h> 50 #include <ufs/ufs/inode.h> 51 52 #include <ufs/ffs/fs.h> 53 #include <ufs/ffs/ffs_extern.h> 54 55 static d_open_t ffs_susp_open; 56 static d_write_t ffs_susp_rdwr; 57 static d_ioctl_t ffs_susp_ioctl; 58 59 static struct cdevsw ffs_susp_cdevsw = { 60 .d_version = D_VERSION, 61 .d_open = ffs_susp_open, 62 .d_read = ffs_susp_rdwr, 63 .d_write = ffs_susp_rdwr, 64 .d_ioctl = ffs_susp_ioctl, 65 .d_name = "ffs_susp", 66 }; 67 68 static struct cdev *ffs_susp_dev; 69 static struct sx ffs_susp_lock; 70 71 static int 72 ffs_susp_suspended(struct mount *mp) 73 { 74 struct ufsmount *ump; 75 76 sx_assert(&ffs_susp_lock, SA_LOCKED); 77 78 ump = VFSTOUFS(mp); 79 if (ump->um_writesuspended) 80 return (1); 81 return (0); 82 } 83 84 static int 85 ffs_susp_open(struct cdev *dev __unused, int flags __unused, 86 int fmt __unused, struct thread *td __unused) 87 { 88 89 return (0); 90 } 91 92 static int 93 ffs_susp_rdwr(struct cdev *dev, struct uio *uio, int ioflag) 94 { 95 int error, i; 96 struct vnode *devvp; 97 struct mount *mp; 98 struct ufsmount *ump; 99 struct buf *bp; 100 void *base; 101 size_t len; 102 ssize_t cnt; 103 struct fs *fs; 104 105 sx_slock(&ffs_susp_lock); 106 107 error = devfs_get_cdevpriv((void **)&mp); 108 if (error != 0) { 109 sx_sunlock(&ffs_susp_lock); 110 return (ENXIO); 111 } 112 113 ump = VFSTOUFS(mp); 114 devvp = ump->um_devvp; 115 fs = ump->um_fs; 116 117 if (ffs_susp_suspended(mp) == 0) { 118 sx_sunlock(&ffs_susp_lock); 119 return (ENXIO); 120 } 121 122 KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE, 123 ("neither UIO_READ or UIO_WRITE")); 124 KASSERT(uio->uio_segflg == UIO_USERSPACE, 125 ("uio->uio_segflg != UIO_USERSPACE")); 126 127 cnt = uio->uio_resid; 128 129 for (i = 0; i < uio->uio_iovcnt; i++) { 130 while (uio->uio_iov[i].iov_len) { 131 base = uio->uio_iov[i].iov_base; 132 len = uio->uio_iov[i].iov_len; 133 if (len > fs->fs_bsize) 134 len = fs->fs_bsize; 135 if (fragoff(fs, uio->uio_offset) != 0 || 136 fragoff(fs, len) != 0) { 137 error = EINVAL; 138 goto out; 139 } 140 error = bread(devvp, btodb(uio->uio_offset), len, 141 NOCRED, &bp); 142 if (error != 0) 143 goto out; 144 if (uio->uio_rw == UIO_WRITE) { 145 error = copyin(base, bp->b_data, len); 146 if (error != 0) { 147 bp->b_flags |= B_INVAL | B_NOCACHE; 148 brelse(bp); 149 goto out; 150 } 151 error = bwrite(bp); 152 if (error != 0) 153 goto out; 154 } else { 155 error = copyout(bp->b_data, base, len); 156 brelse(bp); 157 if (error != 0) 158 goto out; 159 } 160 uio->uio_iov[i].iov_base = 161 (char *)uio->uio_iov[i].iov_base + len; 162 uio->uio_iov[i].iov_len -= len; 163 uio->uio_resid -= len; 164 uio->uio_offset += len; 165 } 166 } 167 168 out: 169 sx_sunlock(&ffs_susp_lock); 170 171 if (uio->uio_resid < cnt) 172 return (0); 173 174 return (error); 175 } 176 177 static int 178 ffs_susp_suspend(struct mount *mp) 179 { 180 struct fs *fs; 181 struct ufsmount *ump; 182 int error; 183 184 sx_assert(&ffs_susp_lock, SA_XLOCKED); 185 186 if (!ffs_own_mount(mp)) 187 return (EINVAL); 188 if (ffs_susp_suspended(mp)) 189 return (EBUSY); 190 191 ump = VFSTOUFS(mp); 192 fs = ump->um_fs; 193 194 /* 195 * Make sure the calling thread is permitted to access the mounted 196 * device. The permissions can change after we unlock the vnode; 197 * it's harmless. 198 */ 199 vn_lock(ump->um_devvp, LK_EXCLUSIVE | LK_RETRY); 200 error = VOP_ACCESS(ump->um_devvp, VREAD | VWRITE, 201 curthread->td_ucred, curthread); 202 VOP_UNLOCK(ump->um_devvp, 0); 203 if (error != 0) 204 return (error); 205 #ifdef MAC 206 if (mac_mount_check_stat(curthread->td_ucred, mp) != 0) 207 return (EPERM); 208 #endif 209 210 if ((error = vfs_write_suspend(mp, VS_SKIP_UNMOUNT)) != 0) 211 return (error); 212 213 ump->um_writesuspended = 1; 214 215 return (0); 216 } 217 218 static void 219 ffs_susp_dtor(void *data) 220 { 221 struct fs *fs; 222 struct ufsmount *ump; 223 struct mount *mp; 224 int error; 225 226 sx_xlock(&ffs_susp_lock); 227 228 mp = (struct mount *)data; 229 ump = VFSTOUFS(mp); 230 fs = ump->um_fs; 231 232 if (ffs_susp_suspended(mp) == 0) { 233 sx_xunlock(&ffs_susp_lock); 234 return; 235 } 236 237 KASSERT((mp->mnt_kern_flag & MNTK_SUSPEND) != 0, 238 ("MNTK_SUSPEND not set")); 239 240 error = ffs_reload(mp, curthread, 1); 241 if (error != 0) 242 panic("failed to unsuspend writes on %s", fs->fs_fsmnt); 243 244 /* 245 * XXX: The status is kept per-process; the vfs_write_resume() routine 246 * asserts that the resuming thread is the same one that called 247 * vfs_write_suspend(). The cdevpriv data, however, is attached 248 * to the file descriptor, e.g. is inherited during fork. Thus, 249 * it's possible that the resuming process will be different from 250 * the one that started the suspension. 251 * 252 * Work around by fooling the check in vfs_write_resume(). 253 */ 254 mp->mnt_susp_owner = curthread; 255 256 vfs_write_resume(mp, 0); 257 vfs_unbusy(mp); 258 ump->um_writesuspended = 0; 259 260 sx_xunlock(&ffs_susp_lock); 261 } 262 263 static int 264 ffs_susp_ioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags, 265 struct thread *td) 266 { 267 struct mount *mp; 268 fsid_t *fsidp; 269 int error; 270 271 /* 272 * No suspend inside the jail. Allowing it would require making 273 * sure that e.g. the devfs ruleset for that jail permits access 274 * to the devvp. 275 */ 276 if (jailed(td->td_ucred)) 277 return (EPERM); 278 279 sx_xlock(&ffs_susp_lock); 280 281 switch (cmd) { 282 case UFSSUSPEND: 283 fsidp = (fsid_t *)addr; 284 mp = vfs_getvfs(fsidp); 285 if (mp == NULL) { 286 error = ENOENT; 287 break; 288 } 289 error = vfs_busy(mp, 0); 290 vfs_rel(mp); 291 if (error != 0) 292 break; 293 error = ffs_susp_suspend(mp); 294 if (error != 0) { 295 vfs_unbusy(mp); 296 break; 297 } 298 error = devfs_set_cdevpriv(mp, ffs_susp_dtor); 299 KASSERT(error == 0, ("devfs_set_cdevpriv failed")); 300 break; 301 case UFSRESUME: 302 error = devfs_get_cdevpriv((void **)&mp); 303 if (error != 0) 304 break; 305 /* 306 * This calls ffs_susp_dtor, which in turn unsuspends the fs. 307 * The dtor expects to be called without lock held, because 308 * sometimes it's called from here, and sometimes due to the 309 * file being closed or process exiting. 310 */ 311 sx_xunlock(&ffs_susp_lock); 312 devfs_clear_cdevpriv(); 313 return (0); 314 default: 315 error = ENXIO; 316 break; 317 } 318 319 sx_xunlock(&ffs_susp_lock); 320 321 return (error); 322 } 323 324 void 325 ffs_susp_initialize(void) 326 { 327 328 sx_init(&ffs_susp_lock, "ffs_susp"); 329 ffs_susp_dev = make_dev(&ffs_susp_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600, 330 "ufssuspend"); 331 } 332 333 void 334 ffs_susp_uninitialize(void) 335 { 336 337 destroy_dev(ffs_susp_dev); 338 sx_destroy(&ffs_susp_lock); 339 } 340