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 ufsmount *ump; 181 int error; 182 183 sx_assert(&ffs_susp_lock, SA_XLOCKED); 184 185 if (!ffs_own_mount(mp)) 186 return (EINVAL); 187 if (ffs_susp_suspended(mp)) 188 return (EBUSY); 189 190 ump = VFSTOUFS(mp); 191 192 /* 193 * Make sure the calling thread is permitted to access the mounted 194 * device. The permissions can change after we unlock the vnode; 195 * it's harmless. 196 */ 197 vn_lock(ump->um_devvp, LK_EXCLUSIVE | LK_RETRY); 198 error = VOP_ACCESS(ump->um_devvp, VREAD | VWRITE, 199 curthread->td_ucred, curthread); 200 VOP_UNLOCK(ump->um_devvp, 0); 201 if (error != 0) 202 return (error); 203 #ifdef MAC 204 if (mac_mount_check_stat(curthread->td_ucred, mp) != 0) 205 return (EPERM); 206 #endif 207 208 if ((error = vfs_write_suspend(mp, VS_SKIP_UNMOUNT)) != 0) 209 return (error); 210 211 ump->um_writesuspended = 1; 212 213 return (0); 214 } 215 216 static void 217 ffs_susp_dtor(void *data) 218 { 219 struct fs *fs; 220 struct ufsmount *ump; 221 struct mount *mp; 222 int error; 223 224 sx_xlock(&ffs_susp_lock); 225 226 mp = (struct mount *)data; 227 ump = VFSTOUFS(mp); 228 fs = ump->um_fs; 229 230 if (ffs_susp_suspended(mp) == 0) { 231 sx_xunlock(&ffs_susp_lock); 232 return; 233 } 234 235 KASSERT((mp->mnt_kern_flag & MNTK_SUSPEND) != 0, 236 ("MNTK_SUSPEND not set")); 237 238 error = ffs_reload(mp, curthread, FFSR_FORCE | FFSR_UNSUSPEND); 239 if (error != 0) 240 panic("failed to unsuspend writes on %s", fs->fs_fsmnt); 241 242 /* 243 * XXX: The status is kept per-process; the vfs_write_resume() routine 244 * asserts that the resuming thread is the same one that called 245 * vfs_write_suspend(). The cdevpriv data, however, is attached 246 * to the file descriptor, e.g. is inherited during fork. Thus, 247 * it's possible that the resuming process will be different from 248 * the one that started the suspension. 249 * 250 * Work around by fooling the check in vfs_write_resume(). 251 */ 252 mp->mnt_susp_owner = curthread; 253 254 vfs_write_resume(mp, 0); 255 vfs_unbusy(mp); 256 ump->um_writesuspended = 0; 257 258 sx_xunlock(&ffs_susp_lock); 259 } 260 261 static int 262 ffs_susp_ioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags, 263 struct thread *td) 264 { 265 struct mount *mp; 266 fsid_t *fsidp; 267 int error; 268 269 /* 270 * No suspend inside the jail. Allowing it would require making 271 * sure that e.g. the devfs ruleset for that jail permits access 272 * to the devvp. 273 */ 274 if (jailed(td->td_ucred)) 275 return (EPERM); 276 277 sx_xlock(&ffs_susp_lock); 278 279 switch (cmd) { 280 case UFSSUSPEND: 281 fsidp = (fsid_t *)addr; 282 mp = vfs_getvfs(fsidp); 283 if (mp == NULL) { 284 error = ENOENT; 285 break; 286 } 287 error = vfs_busy(mp, 0); 288 vfs_rel(mp); 289 if (error != 0) 290 break; 291 error = ffs_susp_suspend(mp); 292 if (error != 0) { 293 vfs_unbusy(mp); 294 break; 295 } 296 error = devfs_set_cdevpriv(mp, ffs_susp_dtor); 297 KASSERT(error == 0, ("devfs_set_cdevpriv failed")); 298 break; 299 case UFSRESUME: 300 error = devfs_get_cdevpriv((void **)&mp); 301 if (error != 0) 302 break; 303 /* 304 * This calls ffs_susp_dtor, which in turn unsuspends the fs. 305 * The dtor expects to be called without lock held, because 306 * sometimes it's called from here, and sometimes due to the 307 * file being closed or process exiting. 308 */ 309 sx_xunlock(&ffs_susp_lock); 310 devfs_clear_cdevpriv(); 311 return (0); 312 default: 313 error = ENXIO; 314 break; 315 } 316 317 sx_xunlock(&ffs_susp_lock); 318 319 return (error); 320 } 321 322 void 323 ffs_susp_initialize(void) 324 { 325 326 sx_init(&ffs_susp_lock, "ffs_susp"); 327 ffs_susp_dev = make_dev(&ffs_susp_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600, 328 "ufssuspend"); 329 } 330 331 void 332 ffs_susp_uninitialize(void) 333 { 334 335 destroy_dev(ffs_susp_dev); 336 sx_destroy(&ffs_susp_lock); 337 } 338