sys/kern/vfs_helper.c

   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. All advertising materials mentioning features or use of this software
  21  *    must display the following acknowledgement:
  22  *      This product includes software developed by the University of
  23  *      California, Berkeley and its contributors.
  24  * 4. Neither the name of the University nor the names of its contributors
  25  *    may be used to endorse or promote products derived from this software
  26  *    without specific prior written permission.
  27  *
  28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  38  * SUCH DAMAGE.
  39  *
  40  * @(#)ufs_vnops.c      8.27 (Berkeley) 5/27/95
  41  * $DragonFly: src/sys/kern/vfs_helper.c,v 1.5 2008/05/25 18:34:46 dillon Exp $
  42  */
  43
  44 #include "opt_quota.h"
  45 #include "opt_suiddir.h"
  46
  47 #include <sys/param.h>
  48 #include <sys/systm.h>
  49 #include <sys/conf.h>
  50 #include <sys/kernel.h>
  51 #include <sys/fcntl.h>
  52 #include <sys/stat.h>
  53 #include <sys/mount.h>
  54 #include <sys/unistd.h>
  55 #include <sys/vnode.h>
  56 #include <sys/file.h>           /* XXX */
  57 #include <sys/proc.h>
  58 #include <sys/priv.h>
  59 #include <sys/jail.h>
  60
  61 /*
  62  * vop_helper_access()
  63  *
  64  *      Provide standard UNIX semanics for VOP_ACCESS, but without the quota
  65  *      code.  This procedure was basically pulled out of UFS.
  66  */
  67 int
  68 vop_helper_access(struct vop_access_args *ap, uid_t ino_uid, gid_t ino_gid,
  69                   mode_t ino_mode, u_int32_t ino_flags)
  70 {
  71         struct vnode *vp = ap->a_vp;
  72         struct ucred *cred = ap->a_cred;
  73         mode_t mask, mode = ap->a_mode;
  74         gid_t *gp;
  75         int i;
  76 #ifdef QUOTA
  77         /*int error;*/
  78 #endif
  79
  80         /*
  81          * Disallow write attempts on read-only filesystems;
  82          * unless the file is a socket, fifo, or a block or
  83          * character device resident on the filesystem.
  84          */
  85         if (mode & VWRITE) {
  86                 switch (vp->v_type) {
  87                 case VDIR:
  88                 case VLNK:
  89                 case VREG:
  90                 case VDATABASE:
  91                         if (vp->v_mount->mnt_flag & MNT_RDONLY)
  92                                 return (EROFS);
  93 #ifdef QUOTA
  94                         /* check quota here XXX */
  95 #endif
  96                         break;
  97                 default:
  98                         break;
  99                 }
 100         }
 101
 102         /* If immutable bit set, nobody gets to write it. */
 103         if ((mode & VWRITE) && (ino_flags & IMMUTABLE))
 104                 return (EPERM);
 105
 106         /* Otherwise, user id 0 always gets access. */
 107         if (cred->cr_uid == 0)
 108                 return (0);
 109
 110         mask = 0;
 111
 112         /* Otherwise, check the owner. */
 113         if (cred->cr_uid == ino_uid) {
 114                 if (mode & VEXEC)
 115                         mask |= S_IXUSR;
 116                 if (mode & VREAD)
 117                         mask |= S_IRUSR;
 118                 if (mode & VWRITE)
 119                         mask |= S_IWUSR;
 120                 return ((ino_mode & mask) == mask ? 0 : EACCES);
 121         }
 122
 123         /* Otherwise, check the groups. */
 124         for (i = 0, gp = cred->cr_groups; i < cred->cr_ngroups; i++, gp++)
 125                 if (ino_gid == *gp) {
 126                         if (mode & VEXEC)
 127                                 mask |= S_IXGRP;
 128                         if (mode & VREAD)
 129                                 mask |= S_IRGRP;
 130                         if (mode & VWRITE)
 131                                 mask |= S_IWGRP;
 132                         return ((ino_mode & mask) == mask ? 0 : EACCES);
 133                 }
 134
 135         /* Otherwise, check everyone else. */
 136         if (mode & VEXEC)
 137                 mask |= S_IXOTH;
 138         if (mode & VREAD)
 139                 mask |= S_IROTH;
 140         if (mode & VWRITE)
 141                 mask |= S_IWOTH;
 142         return ((ino_mode & mask) == mask ? 0 : EACCES);
 143 }
 144
 145 int
 146 vop_helper_setattr_flags(u_int32_t *ino_flags, u_int32_t vaflags,
 147                          uid_t uid, struct ucred *cred)
 148 {
 149         int error;
 150
 151         /*
 152          * If uid doesn't match only a privileged user can change the flags
 153          */
 154         if (cred->cr_uid != uid &&
 155             (error = priv_check_cred(cred, PRIV_VFS_SYSFLAGS, 0))) {
 156                 return(error);
 157         }
 158         if (cred->cr_uid == 0 &&
 159             (!jailed(cred)|| jail_chflags_allowed)) {
 160                 if ((*ino_flags & (SF_NOUNLINK|SF_IMMUTABLE|SF_APPEND)) &&
 161                     securelevel > 0)
 162                         return (EPERM);
 163                 *ino_flags = vaflags;
 164         } else {
 165                 if (*ino_flags & (SF_NOUNLINK|SF_IMMUTABLE|SF_APPEND) ||
 166                     (vaflags & UF_SETTABLE) != vaflags)
 167                         return (EPERM);
 168                 *ino_flags &= SF_SETTABLE;
 169                 *ino_flags |= vaflags & UF_SETTABLE;
 170         }
 171         return(0);
 172 }
 173
 174 /*
 175  * This helper function may be used by VFSs to implement UNIX initial
 176  * ownership semantics when creating new objects inside directories.
 177  */
 178 uid_t
 179 vop_helper_create_uid(struct mount *mp, mode_t dmode, uid_t duid,
 180                       struct ucred *cred, mode_t *modep)
 181 {
 182 #ifdef SUIDDIR
 183         if ((mp->mnt_flag & MNT_SUIDDIR) && (dmode & S_ISUID) &&
 184             duid != cred->cr_uid && duid) {
 185                 *modep &= ~07111;
 186                 return(duid);
 187         }
 188 #endif
 189         return(cred->cr_uid);
 190 }
 191
 192 /*
 193  * This helper may be used by VFSs to implement unix chmod semantics.
 194  *
 195  * XXX TEMPORARY chmod override for VCHR devices.  Allow the device to
 196  *               override the uid if the uid is not root.  This is used
 197  *               by pty's to set the owner for the related tty.
 198  *
 199  * XXX REMOVE THE OVERRIDE WHEN DEVFS IS MERGED.
 200  */
 201 int
 202 vop_helper_chmod(struct vnode *vp, mode_t new_mode, struct ucred *cred,
 203                  uid_t cur_uid, gid_t cur_gid, mode_t *cur_modep)
 204 {
 205         int error;
 206         cdev_t dev;
 207
 208         /*
 209          * HACK to support openpty().  If called by root openpty() chown's
 210          * the tty and we allow this.  If not called by root the kernel
 211          * saves the uid in si_uid and if the tty is not owned by root we
 212          * override it here.
 213          *
 214          * NOTE: The vnode might not be open so v_rdev might not be assigned.
 215          */
 216         if (vp->v_type == VCHR && cur_uid == 0) {
 217                 if ((dev = vp->v_rdev) == NULL)
 218                         dev = get_dev(vp->v_umajor, vp->v_uminor);
 219                 if (dev)
 220                         cur_uid = dev->si_uid;
 221         }
 222
 223         if (cred->cr_uid != cur_uid) {
 224                 error = priv_check_cred(cred, PRIV_ROOT, PRISON_ROOT);
 225                 if (error)
 226                         return (error);
 227         }
 228         if (cred->cr_uid) {
 229                 if (vp->v_type != VDIR && (*cur_modep & S_ISTXT))
 230                         return (EFTYPE);
 231                 if (!groupmember(cur_gid, cred) && (*cur_modep & S_ISGID))
 232                         return (EPERM);
 233         }
 234         *cur_modep &= ~ALLPERMS;
 235         *cur_modep |= new_mode & ALLPERMS;
 236         return(0);
 237 }
 238
 239 /*
 240  * This helper may be used by VFSs to implement unix chown semantics.
 241  */
 242 int
 243 vop_helper_chown(struct vnode *vp, uid_t new_uid, gid_t new_gid,
 244                  struct ucred *cred,
 245                  uid_t *cur_uidp, gid_t *cur_gidp, mode_t *cur_modep)
 246 {
 247         gid_t ogid;
 248         uid_t ouid;
 249         int error;
 250
 251         if (new_uid == (uid_t)VNOVAL)
 252                 new_uid = *cur_uidp;
 253         if (new_gid == (gid_t)VNOVAL)
 254                 new_gid = *cur_gidp;
 255
 256         /*
 257          * If we don't own the file, are trying to change the owner
 258          * of the file, or are not a member of the target group,
 259          * the caller must be privileged or the call fails.
 260          */
 261         if ((cred->cr_uid != *cur_uidp || new_uid != *cur_uidp ||
 262             (new_gid != *cur_gidp && !(cred->cr_gid == new_gid ||
 263             groupmember(new_gid, cred)))) &&
 264             (error = priv_check_cred(cred, PRIV_VFS_CHOWN, 0))) {
 265                 return (error);
 266         }
 267         ogid = *cur_gidp;
 268         ouid = *cur_uidp;
 269         /* XXX QUOTA CODE */
 270         *cur_uidp = new_uid;
 271         *cur_gidp = new_gid;
 272         /* XXX QUOTA CODE */
 273
 274         /*
 275          * DragonFly clears both SUID and SGID if either the owner or
 276          * group is changed and root isn't doing it.  If root is doing
 277          * it we do not clear SUID/SGID.
 278          */
 279         if (cred->cr_uid != 0 && (ouid != new_uid || ogid != new_gid))
 280                 *cur_modep &= ~(S_ISUID | S_ISGID);
 281         return(0);
 282 }
 283