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/kernel.h>
  50 #include <sys/fcntl.h>
  51 #include <sys/stat.h>
  52 #include <sys/mount.h>
  53 #include <sys/unistd.h>
  54 #include <sys/vnode.h>
  55 #include <sys/file.h>           /* XXX */
  56 #include <sys/proc.h>
  57 #include <sys/jail.h>
  58
  59 /*
  60  * vop_helper_access()
  61  *
  62  *      Provide standard UNIX semanics for VOP_ACCESS, but without the quota
  63  *      code.  This procedure was basically pulled out of UFS.
  64  */
  65 int
  66 vop_helper_access(struct vop_access_args *ap, uid_t ino_uid, gid_t ino_gid,
  67                   mode_t ino_mode, u_int32_t ino_flags)
  68 {
  69         struct vnode *vp = ap->a_vp;
  70         struct ucred *cred = ap->a_cred;
  71         mode_t mask, mode = ap->a_mode;
  72         gid_t *gp;
  73         int i;
  74 #ifdef QUOTA
  75         /*int error;*/
  76 #endif
  77
  78         /*
  79          * Disallow write attempts on read-only filesystems;
  80          * unless the file is a socket, fifo, or a block or
  81          * character device resident on the filesystem.
  82          */
  83         if (mode & VWRITE) {
  84                 switch (vp->v_type) {
  85                 case VDIR:
  86                 case VLNK:
  87                 case VREG:
  88                 case VDATABASE:
  89                         if (vp->v_mount->mnt_flag & MNT_RDONLY)
  90                                 return (EROFS);
  91 #ifdef QUOTA
  92                         /* check quota here XXX */
  93 #endif
  94                         break;
  95                 default:
  96                         break;
  97                 }
  98         }
  99
 100         /* If immutable bit set, nobody gets to write it. */
 101         if ((mode & VWRITE) && (ino_flags & IMMUTABLE))
 102                 return (EPERM);
 103
 104         /* Otherwise, user id 0 always gets access. */
 105         if (cred->cr_uid == 0)
 106                 return (0);
 107
 108         mask = 0;
 109
 110         /* Otherwise, check the owner. */
 111         if (cred->cr_uid == ino_uid) {
 112                 if (mode & VEXEC)
 113                         mask |= S_IXUSR;
 114                 if (mode & VREAD)
 115                         mask |= S_IRUSR;
 116                 if (mode & VWRITE)
 117                         mask |= S_IWUSR;
 118                 return ((ino_mode & mask) == mask ? 0 : EACCES);
 119         }
 120
 121         /* Otherwise, check the groups. */
 122         for (i = 0, gp = cred->cr_groups; i < cred->cr_ngroups; i++, gp++)
 123                 if (ino_gid == *gp) {
 124                         if (mode & VEXEC)
 125                                 mask |= S_IXGRP;
 126                         if (mode & VREAD)
 127                                 mask |= S_IRGRP;
 128                         if (mode & VWRITE)
 129                                 mask |= S_IWGRP;
 130                         return ((ino_mode & mask) == mask ? 0 : EACCES);
 131                 }
 132
 133         /* Otherwise, check everyone else. */
 134         if (mode & VEXEC)
 135                 mask |= S_IXOTH;
 136         if (mode & VREAD)
 137                 mask |= S_IROTH;
 138         if (mode & VWRITE)
 139                 mask |= S_IWOTH;
 140         return ((ino_mode & mask) == mask ? 0 : EACCES);
 141 }
 142
 143 int
 144 vop_helper_setattr_flags(u_int32_t *ino_flags, u_int32_t vaflags,
 145                          uid_t uid, struct ucred *cred)
 146 {
 147         int error;
 148
 149         /*
 150          * If uid doesn't match only the super-user can change the flags
 151          */
 152         if (cred->cr_uid != uid &&
 153             (error = suser_cred(cred, PRISON_ROOT))) {
 154                 return(error);
 155         }
 156         if (cred->cr_uid == 0 &&
 157             (!jailed(cred)|| jail_chflags_allowed)) {
 158                 if ((*ino_flags & (SF_NOUNLINK|SF_IMMUTABLE|SF_APPEND)) &&
 159                     securelevel > 0)
 160                         return (EPERM);
 161                 *ino_flags = vaflags;
 162         } else {
 163                 if (*ino_flags & (SF_NOUNLINK|SF_IMMUTABLE|SF_APPEND) ||
 164                     (vaflags & UF_SETTABLE) != vaflags)
 165                         return (EPERM);
 166                 *ino_flags &= SF_SETTABLE;
 167                 *ino_flags |= vaflags & UF_SETTABLE;
 168         }
 169         return(0);
 170 }
 171
 172 /*
 173  * This helper function may be used by VFSs to implement UNIX initial
 174  * ownership semantics when creating new objects inside directories.
 175  */
 176 uid_t
 177 vop_helper_create_uid(struct mount *mp, mode_t dmode, uid_t duid,
 178                       struct ucred *cred, mode_t *modep)
 179 {
 180 #ifdef SUIDDIR
 181         if ((mp->mnt_flag & MNT_SUIDDIR) && (dmode & S_ISUID) &&
 182             duid != cred->cr_uid && duid) {
 183                 *modep &= ~07111;
 184                 return(duid);
 185         }
 186 #endif
 187         return(cred->cr_uid);
 188 }
 189
 190 /*
 191  * This helper may be used by VFSs to implement unix chmod semantics.
 192  */
 193 int
 194 vop_helper_chmod(struct vnode *vp, mode_t new_mode, struct ucred *cred,
 195                  uid_t cur_uid, gid_t cur_gid, mode_t *cur_modep)
 196 {
 197         int error;
 198
 199         if (cred->cr_uid != cur_uid) {
 200                 error = suser_cred(cred, PRISON_ROOT);
 201                 if (error)
 202                         return (error);
 203         }
 204         if (cred->cr_uid) {
 205                 if (vp->v_type != VDIR && (*cur_modep & S_ISTXT))
 206                         return (EFTYPE);
 207                 if (!groupmember(cur_gid, cred) && (*cur_modep & S_ISGID))
 208                         return (EPERM);
 209         }
 210         *cur_modep &= ~ALLPERMS;
 211         *cur_modep |= new_mode & ALLPERMS;
 212         return(0);
 213 }
 214
 215 /*
 216  * This helper may be used by VFSs to implement unix chown semantics.
 217  */
 218 int
 219 vop_helper_chown(struct vnode *vp, uid_t new_uid, gid_t new_gid,
 220                  struct ucred *cred,
 221                  uid_t *cur_uidp, gid_t *cur_gidp, mode_t *cur_modep)
 222 {
 223         gid_t ogid;
 224         uid_t ouid;
 225         int error;
 226
 227         if (new_uid == (uid_t)VNOVAL)
 228                 new_uid = *cur_uidp;
 229         if (new_gid == (gid_t)VNOVAL)
 230                 new_gid = *cur_gidp;
 231
 232         /*
 233          * If we don't own the file, are trying to change the owner
 234          * of the file, or are not a member of the target group,
 235          * the caller must be superuser or the call fails.
 236          */
 237         if ((cred->cr_uid != *cur_uidp || new_uid != *cur_uidp ||
 238             (new_gid != *cur_gidp && !(cred->cr_gid == new_gid ||
 239             groupmember(new_gid, cred)))) &&
 240             (error = suser_cred(cred, PRISON_ROOT))) {
 241                 return (error);
 242         }
 243         ogid = *cur_gidp;
 244         ouid = *cur_uidp;
 245         /* XXX QUOTA CODE */
 246         *cur_uidp = new_uid;
 247         *cur_gidp = new_gid;
 248         /* XXX QUOTA CODE */
 249         if (cred->cr_uid != 0 && (ouid != new_uid || ogid != new_gid))
 250                 *cur_modep &= ~(S_ISUID | S_ISGID);
 251         return(0);
 252 }
 253