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/priv.h>
  58 #include <sys/jail.h>
  59
  60 /*
  61  * vop_helper_access()
  62  *
  63  *      Provide standard UNIX semanics for VOP_ACCESS, but without the quota
  64  *      code.  This procedure was basically pulled out of UFS.
  65  */
  66 int
  67 vop_helper_access(struct vop_access_args *ap, uid_t ino_uid, gid_t ino_gid,
  68                   mode_t ino_mode, u_int32_t ino_flags)
  69 {
  70         struct vnode *vp = ap->a_vp;
  71         struct ucred *cred = ap->a_cred;
  72         mode_t mask, mode = ap->a_mode;
  73         gid_t *gp;
  74         int i;
  75 #ifdef QUOTA
  76         /*int error;*/
  77 #endif
  78
  79         /*
  80          * Disallow write attempts on read-only filesystems;
  81          * unless the file is a socket, fifo, or a block or
  82          * character device resident on the filesystem.
  83          */
  84         if (mode & VWRITE) {
  85                 switch (vp->v_type) {
  86                 case VDIR:
  87                 case VLNK:
  88                 case VREG:
  89                 case VDATABASE:
  90                         if (vp->v_mount->mnt_flag & MNT_RDONLY)
  91                                 return (EROFS);
  92 #ifdef QUOTA
  93                         /* check quota here XXX */
  94 #endif
  95                         break;
  96                 default:
  97                         break;
  98                 }
  99         }
 100
 101         /* If immutable bit set, nobody gets to write it. */
 102         if ((mode & VWRITE) && (ino_flags & IMMUTABLE))
 103                 return (EPERM);
 104
 105         /* Otherwise, user id 0 always gets access. */
 106         if (cred->cr_uid == 0)
 107                 return (0);
 108
 109         mask = 0;
 110
 111         /* Otherwise, check the owner. */
 112         if (cred->cr_uid == ino_uid) {
 113                 if (mode & VEXEC)
 114                         mask |= S_IXUSR;
 115                 if (mode & VREAD)
 116                         mask |= S_IRUSR;
 117                 if (mode & VWRITE)
 118                         mask |= S_IWUSR;
 119                 return ((ino_mode & mask) == mask ? 0 : EACCES);
 120         }
 121
 122         /* Otherwise, check the groups. */
 123         for (i = 0, gp = cred->cr_groups; i < cred->cr_ngroups; i++, gp++)
 124                 if (ino_gid == *gp) {
 125                         if (mode & VEXEC)
 126                                 mask |= S_IXGRP;
 127                         if (mode & VREAD)
 128                                 mask |= S_IRGRP;
 129                         if (mode & VWRITE)
 130                                 mask |= S_IWGRP;
 131                         return ((ino_mode & mask) == mask ? 0 : EACCES);
 132                 }
 133
 134         /* Otherwise, check everyone else. */
 135         if (mode & VEXEC)
 136                 mask |= S_IXOTH;
 137         if (mode & VREAD)
 138                 mask |= S_IROTH;
 139         if (mode & VWRITE)
 140                 mask |= S_IWOTH;
 141         return ((ino_mode & mask) == mask ? 0 : EACCES);
 142 }
 143
 144 int
 145 vop_helper_setattr_flags(u_int32_t *ino_flags, u_int32_t vaflags,
 146                          uid_t uid, struct ucred *cred)
 147 {
 148         int error;
 149
 150         /*
 151          * If uid doesn't match only the super-user can change the flags
 152          */
 153         if (cred->cr_uid != uid &&
 154             (error = priv_check_cred(cred, PRIV_ROOT, PRISON_ROOT))) {
 155                 return(error);
 156         }
 157         if (cred->cr_uid == 0 &&
 158             (!jailed(cred)|| jail_chflags_allowed)) {
 159                 if ((*ino_flags & (SF_NOUNLINK|SF_IMMUTABLE|SF_APPEND)) &&
 160                     securelevel > 0)
 161                         return (EPERM);
 162                 *ino_flags = vaflags;
 163         } else {
 164                 if (*ino_flags & (SF_NOUNLINK|SF_IMMUTABLE|SF_APPEND) ||
 165                     (vaflags & UF_SETTABLE) != vaflags)
 166                         return (EPERM);
 167                 *ino_flags &= SF_SETTABLE;
 168                 *ino_flags |= vaflags & UF_SETTABLE;
 169         }
 170         return(0);
 171 }
 172
 173 /*
 174  * This helper function may be used by VFSs to implement UNIX initial
 175  * ownership semantics when creating new objects inside directories.
 176  */
 177 uid_t
 178 vop_helper_create_uid(struct mount *mp, mode_t dmode, uid_t duid,
 179                       struct ucred *cred, mode_t *modep)
 180 {
 181 #ifdef SUIDDIR
 182         if ((mp->mnt_flag & MNT_SUIDDIR) && (dmode & S_ISUID) &&
 183             duid != cred->cr_uid && duid) {
 184                 *modep &= ~07111;
 185                 return(duid);
 186         }
 187 #endif
 188         return(cred->cr_uid);
 189 }
 190
 191 /*
 192  * This helper may be used by VFSs to implement unix chmod semantics.
 193  */
 194 int
 195 vop_helper_chmod(struct vnode *vp, mode_t new_mode, struct ucred *cred,
 196                  uid_t cur_uid, gid_t cur_gid, mode_t *cur_modep)
 197 {
 198         int error;
 199
 200         if (cred->cr_uid != cur_uid) {
 201                 error = priv_check_cred(cred, PRIV_ROOT, PRISON_ROOT);
 202                 if (error)
 203                         return (error);
 204         }
 205         if (cred->cr_uid) {
 206                 if (vp->v_type != VDIR && (*cur_modep & S_ISTXT))
 207                         return (EFTYPE);
 208                 if (!groupmember(cur_gid, cred) && (*cur_modep & S_ISGID))
 209                         return (EPERM);
 210         }
 211         *cur_modep &= ~ALLPERMS;
 212         *cur_modep |= new_mode & ALLPERMS;
 213         return(0);
 214 }
 215
 216 /*
 217  * This helper may be used by VFSs to implement unix chown semantics.
 218  */
 219 int
 220 vop_helper_chown(struct vnode *vp, uid_t new_uid, gid_t new_gid,
 221                  struct ucred *cred,
 222                  uid_t *cur_uidp, gid_t *cur_gidp, mode_t *cur_modep)
 223 {
 224         gid_t ogid;
 225         uid_t ouid;
 226         int error;
 227
 228         if (new_uid == (uid_t)VNOVAL)
 229                 new_uid = *cur_uidp;
 230         if (new_gid == (gid_t)VNOVAL)
 231                 new_gid = *cur_gidp;
 232
 233         /*
 234          * If we don't own the file, are trying to change the owner
 235          * of the file, or are not a member of the target group,
 236          * the caller must be superuser or the call fails.
 237          */
 238         if ((cred->cr_uid != *cur_uidp || new_uid != *cur_uidp ||
 239             (new_gid != *cur_gidp && !(cred->cr_gid == new_gid ||
 240             groupmember(new_gid, cred)))) &&
 241             (error = priv_check_cred(cred, PRIV_ROOT, PRISON_ROOT))) {
 242                 return (error);
 243         }
 244         ogid = *cur_gidp;
 245         ouid = *cur_uidp;
 246         /* XXX QUOTA CODE */
 247         *cur_uidp = new_uid;
 248         *cur_gidp = new_gid;
 249         /* XXX QUOTA CODE */
 250         if (cred->cr_uid != 0 && (ouid != new_uid || ogid != new_gid))
 251                 *cur_modep &= ~(S_ISUID | S_ISGID);
 252         return(0);
 253 }
 254