1 /* 2 * (The copyright below applies to ufs_access()) 3 * 4 * Copyright (c) 1982, 1986, 1989, 1993, 1995 5 * The Regents of the University of California. All rights reserved. 6 * (c) UNIX System Laboratories, Inc. 7 * All or some portions of this file are derived from material licensed 8 * to the University of California by American Telephone and Telegraph 9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 10 * the permission of UNIX System Laboratories, Inc. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)ufs_vnops.c 8.27 (Berkeley) 5/27/95 37 * $DragonFly: src/sys/kern/vfs_helper.c,v 1.5 2008/05/25 18:34:46 dillon Exp $ 38 */ 39 40 #include "opt_quota.h" 41 #include "opt_suiddir.h" 42 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 #include <sys/conf.h> 46 #include <sys/kernel.h> 47 #include <sys/fcntl.h> 48 #include <sys/stat.h> 49 #include <sys/mount.h> 50 #include <sys/unistd.h> 51 #include <sys/vnode.h> 52 #include <sys/file.h> /* XXX */ 53 #include <sys/proc.h> 54 #include <sys/priv.h> 55 #include <sys/jail.h> 56 #include <sys/sysctl.h> 57 #include <sys/sfbuf.h> 58 #include <vm/vm_extern.h> 59 #include <vm/vm_object.h> 60 #include <vm/vm_page2.h> 61 62 #ifdef LWBUF_IS_OPTIMAL 63 64 static int vm_read_shortcut_enable = 1; 65 static long vm_read_shortcut_count; 66 static long vm_read_shortcut_failed; 67 SYSCTL_INT(_vm, OID_AUTO, read_shortcut_enable, CTLFLAG_RW, 68 &vm_read_shortcut_enable, 0, "Direct vm_object vop_read shortcut"); 69 SYSCTL_LONG(_vm, OID_AUTO, read_shortcut_count, CTLFLAG_RW, 70 &vm_read_shortcut_count, 0, "Statistics"); 71 SYSCTL_LONG(_vm, OID_AUTO, read_shortcut_failed, CTLFLAG_RW, 72 &vm_read_shortcut_failed, 0, "Statistics"); 73 74 #endif 75 76 /* 77 * vop_helper_access() 78 * 79 * Provide standard UNIX semanics for VOP_ACCESS, but without the quota 80 * code. This procedure was basically pulled out of UFS. 81 */ 82 int 83 vop_helper_access(struct vop_access_args *ap, uid_t ino_uid, gid_t ino_gid, 84 mode_t ino_mode, u_int32_t ino_flags) 85 { 86 struct vnode *vp = ap->a_vp; 87 struct ucred *cred = ap->a_cred; 88 mode_t mask, mode = ap->a_mode; 89 gid_t *gp; 90 int i; 91 uid_t proc_uid; 92 gid_t proc_gid; 93 94 if (ap->a_flags & AT_EACCESS) { 95 proc_uid = cred->cr_uid; 96 proc_gid = cred->cr_gid; 97 } else { 98 proc_uid = cred->cr_ruid; 99 proc_gid = cred->cr_rgid; 100 } 101 102 /* 103 * Disallow write attempts on read-only filesystems; 104 * unless the file is a socket, fifo, or a block or 105 * character device resident on the filesystem. 106 */ 107 if (mode & VWRITE) { 108 switch (vp->v_type) { 109 case VDIR: 110 case VLNK: 111 case VREG: 112 case VDATABASE: 113 if (vp->v_mount->mnt_flag & MNT_RDONLY) 114 return (EROFS); 115 break; 116 default: 117 break; 118 } 119 } 120 121 /* If immutable bit set, nobody gets to write it. */ 122 if ((mode & VWRITE) && (ino_flags & IMMUTABLE)) 123 return (EPERM); 124 125 /* Otherwise, user id 0 always gets access. */ 126 if (proc_uid == 0) 127 return (0); 128 129 mask = 0; 130 131 /* Otherwise, check the owner. */ 132 if (proc_uid == ino_uid) { 133 if (mode & VEXEC) 134 mask |= S_IXUSR; 135 if (mode & VREAD) 136 mask |= S_IRUSR; 137 if (mode & VWRITE) 138 mask |= S_IWUSR; 139 return ((ino_mode & mask) == mask ? 0 : EACCES); 140 } 141 142 /* 143 * Otherwise, check the groups. 144 * We must special-case the primary group to, if needed, check against 145 * the real gid and not the effective one. 146 */ 147 if (proc_gid == ino_gid) { 148 if (mode & VEXEC) 149 mask |= S_IXGRP; 150 if (mode & VREAD) 151 mask |= S_IRGRP; 152 if (mode & VWRITE) 153 mask |= S_IWGRP; 154 return ((ino_mode & mask) == mask ? 0 : EACCES); 155 } 156 for (i = 1, gp = &cred->cr_groups[1]; i < cred->cr_ngroups; i++, gp++) 157 if (ino_gid == *gp) { 158 if (mode & VEXEC) 159 mask |= S_IXGRP; 160 if (mode & VREAD) 161 mask |= S_IRGRP; 162 if (mode & VWRITE) 163 mask |= S_IWGRP; 164 return ((ino_mode & mask) == mask ? 0 : EACCES); 165 } 166 167 /* Otherwise, check everyone else. */ 168 if (mode & VEXEC) 169 mask |= S_IXOTH; 170 if (mode & VREAD) 171 mask |= S_IROTH; 172 if (mode & VWRITE) 173 mask |= S_IWOTH; 174 return ((ino_mode & mask) == mask ? 0 : EACCES); 175 } 176 177 int 178 vop_helper_setattr_flags(u_int32_t *ino_flags, u_int32_t vaflags, 179 uid_t uid, struct ucred *cred) 180 { 181 int error; 182 183 /* 184 * If uid doesn't match only a privileged user can change the flags 185 */ 186 if (cred->cr_uid != uid && 187 (error = priv_check_cred(cred, PRIV_VFS_SYSFLAGS, 0))) { 188 return(error); 189 } 190 if (cred->cr_uid == 0 && 191 (!jailed(cred)|| jail_chflags_allowed)) { 192 if ((*ino_flags & (SF_NOUNLINK|SF_IMMUTABLE|SF_APPEND)) && 193 securelevel > 0) 194 return (EPERM); 195 *ino_flags = vaflags; 196 } else { 197 if (*ino_flags & (SF_NOUNLINK|SF_IMMUTABLE|SF_APPEND) || 198 (vaflags & UF_SETTABLE) != vaflags) 199 return (EPERM); 200 *ino_flags &= SF_SETTABLE; 201 *ino_flags |= vaflags & UF_SETTABLE; 202 } 203 return(0); 204 } 205 206 /* 207 * This helper function may be used by VFSs to implement UNIX initial 208 * ownership semantics when creating new objects inside directories. 209 */ 210 uid_t 211 vop_helper_create_uid(struct mount *mp, mode_t dmode, uid_t duid, 212 struct ucred *cred, mode_t *modep) 213 { 214 #ifdef SUIDDIR 215 if ((mp->mnt_flag & MNT_SUIDDIR) && (dmode & S_ISUID) && 216 duid != cred->cr_uid && duid) { 217 *modep &= ~07111; 218 return(duid); 219 } 220 #endif 221 return(cred->cr_uid); 222 } 223 224 /* 225 * This helper may be used by VFSs to implement unix chmod semantics. 226 */ 227 int 228 vop_helper_chmod(struct vnode *vp, mode_t new_mode, struct ucred *cred, 229 uid_t cur_uid, gid_t cur_gid, mode_t *cur_modep) 230 { 231 int error; 232 233 if (cred->cr_uid != cur_uid) { 234 error = priv_check_cred(cred, PRIV_VFS_CHMOD, 0); 235 if (error) 236 return (error); 237 } 238 if (cred->cr_uid) { 239 if (vp->v_type != VDIR && (*cur_modep & S_ISTXT)) 240 return (EFTYPE); 241 if (!groupmember(cur_gid, cred) && (*cur_modep & S_ISGID)) 242 return (EPERM); 243 } 244 *cur_modep &= ~ALLPERMS; 245 *cur_modep |= new_mode & ALLPERMS; 246 return(0); 247 } 248 249 /* 250 * This helper may be used by VFSs to implement unix chown semantics. 251 */ 252 int 253 vop_helper_chown(struct vnode *vp, uid_t new_uid, gid_t new_gid, 254 struct ucred *cred, 255 uid_t *cur_uidp, gid_t *cur_gidp, mode_t *cur_modep) 256 { 257 gid_t ogid; 258 uid_t ouid; 259 int error; 260 261 if (new_uid == (uid_t)VNOVAL) 262 new_uid = *cur_uidp; 263 if (new_gid == (gid_t)VNOVAL) 264 new_gid = *cur_gidp; 265 266 /* 267 * If we don't own the file, are trying to change the owner 268 * of the file, or are not a member of the target group, 269 * the caller must be privileged or the call fails. 270 */ 271 if ((cred->cr_uid != *cur_uidp || new_uid != *cur_uidp || 272 (new_gid != *cur_gidp && !(cred->cr_gid == new_gid || 273 groupmember(new_gid, cred)))) && 274 (error = priv_check_cred(cred, PRIV_VFS_CHOWN, 0))) { 275 return (error); 276 } 277 ogid = *cur_gidp; 278 ouid = *cur_uidp; 279 /* XXX QUOTA CODE */ 280 *cur_uidp = new_uid; 281 *cur_gidp = new_gid; 282 /* XXX QUOTA CODE */ 283 284 /* 285 * DragonFly clears both SUID and SGID if either the owner or 286 * group is changed and root isn't doing it. If root is doing 287 * it we do not clear SUID/SGID. 288 */ 289 if (cred->cr_uid != 0 && (ouid != new_uid || ogid != new_gid)) 290 *cur_modep &= ~(S_ISUID | S_ISGID); 291 return(0); 292 } 293 294 #ifdef LWBUF_IS_OPTIMAL 295 296 /* 297 * A VFS can call this function to try to dispose of a read request 298 * directly from the VM system, pretty much bypassing almost all VFS 299 * overhead except for atime updates. 300 * 301 * If 0 is returned some or all of the uio was handled. The caller must 302 * check the uio and handle the remainder. 303 * 304 * The caller must fail on a non-zero error. 305 */ 306 int 307 vop_helper_read_shortcut(struct vop_read_args *ap) 308 { 309 struct vnode *vp; 310 struct uio *uio; 311 struct lwbuf *lwb; 312 struct lwbuf lwb_cache; 313 vm_object_t obj; 314 vm_page_t m; 315 int offset; 316 int n; 317 int error; 318 319 vp = ap->a_vp; 320 uio = ap->a_uio; 321 322 /* 323 * We can't short-cut if there is no VM object or this is a special 324 * UIO_NOCOPY read (typically from VOP_STRATEGY()). We also can't 325 * do this if we cannot extract the filesize from the vnode. 326 */ 327 if (vm_read_shortcut_enable == 0) 328 return(0); 329 if (vp->v_object == NULL || uio->uio_segflg == UIO_NOCOPY) 330 return(0); 331 if (vp->v_filesize == NOOFFSET) 332 return(0); 333 if (uio->uio_resid == 0) 334 return(0); 335 336 /* 337 * Iterate the uio on a page-by-page basis 338 * 339 * XXX can we leave the object held shared during the uiomove()? 340 */ 341 ++vm_read_shortcut_count; 342 obj = vp->v_object; 343 vm_object_hold_shared(obj); 344 345 error = 0; 346 while (uio->uio_resid && error == 0) { 347 offset = (int)uio->uio_offset & PAGE_MASK; 348 n = PAGE_SIZE - offset; 349 if (n > uio->uio_resid) 350 n = uio->uio_resid; 351 if (vp->v_filesize < uio->uio_offset) 352 break; 353 if (uio->uio_offset + n > vp->v_filesize) 354 n = vp->v_filesize - uio->uio_offset; 355 if (n == 0) 356 break; /* hit EOF */ 357 358 m = vm_page_lookup_busy_try(obj, OFF_TO_IDX(uio->uio_offset), 359 FALSE, &error); 360 if (error || m == NULL) { 361 ++vm_read_shortcut_failed; 362 error = 0; 363 break; 364 } 365 if ((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 366 ++vm_read_shortcut_failed; 367 vm_page_wakeup(m); 368 break; 369 } 370 lwb = lwbuf_alloc(m, &lwb_cache); 371 372 /* 373 * Use a no-fault uiomove() to avoid deadlocking against 374 * our VM object (which could livelock on the same object 375 * due to shared-vs-exclusive), or deadlocking against 376 * our busied page. Returns EFAULT on any fault which 377 * winds up diving a vnode. 378 */ 379 error = uiomove_nofault((char *)lwbuf_kva(lwb) + offset, 380 n, uio); 381 382 vm_page_flag_set(m, PG_REFERENCED); 383 lwbuf_free(lwb); 384 vm_page_wakeup(m); 385 } 386 vm_object_drop(obj); 387 388 /* 389 * Ignore EFAULT since we used uiomove_nofault(), causes caller 390 * to fall-back to normal code for this case. 391 */ 392 if (error == EFAULT) 393 error = 0; 394 395 return (error); 396 } 397 398 #else 399 400 /* 401 * If lwbuf's aren't optimal then it's best to just use the buffer 402 * cache. 403 */ 404 int 405 vop_helper_read_shortcut(struct vop_read_args *ap) 406 { 407 return(0); 408 } 409 410 #endif 411