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         uid_t proc_uid;
  77         gid_t proc_gid;
  78
  79         if (ap->a_flags & AT_EACCESS) {
  80                 proc_uid = cred->cr_uid;
  81                 proc_gid = cred->cr_gid;
  82         } else {
  83                 proc_uid = cred->cr_ruid;
  84                 proc_gid = cred->cr_rgid;
  85         }
  86
  87         /*
  88          * Disallow write attempts on read-only filesystems;
  89          * unless the file is a socket, fifo, or a block or
  90          * character device resident on the filesystem.
  91          */
  92         if (mode & VWRITE) {
  93                 switch (vp->v_type) {
  94                 case VDIR:
  95                 case VLNK:
  96                 case VREG:
  97                 case VDATABASE:
  98                         if (vp->v_mount->mnt_flag & MNT_RDONLY)
  99                                 return (EROFS);
 100                         break;
 101                 default:
 102                         break;
 103                 }
 104         }
 105
 106         /* If immutable bit set, nobody gets to write it. */
 107         if ((mode & VWRITE) && (ino_flags & IMMUTABLE))
 108                 return (EPERM);
 109
 110         /* Otherwise, user id 0 always gets access. */
 111         if (proc_uid == 0)
 112                 return (0);
 113
 114         mask = 0;
 115
 116         /* Otherwise, check the owner. */
 117         if (proc_uid == ino_uid) {
 118                 if (mode & VEXEC)
 119                         mask |= S_IXUSR;
 120                 if (mode & VREAD)
 121                         mask |= S_IRUSR;
 122                 if (mode & VWRITE)
 123                         mask |= S_IWUSR;
 124                 return ((ino_mode & mask) == mask ? 0 : EACCES);
 125         }
 126
 127         /*
 128          * Otherwise, check the groups.
 129          * We must special-case the primary group to, if needed, check against
 130          * the real gid and not the effective one.
 131          */
 132         if (proc_gid == ino_gid) {
 133                 if (mode & VEXEC)
 134                         mask |= S_IXGRP;
 135                 if (mode & VREAD)
 136                         mask |= S_IRGRP;
 137                 if (mode & VWRITE)
 138                         mask |= S_IWGRP;
 139                 return ((ino_mode & mask) == mask ? 0 : EACCES);
 140         }
 141         for (i = 1, gp = &cred->cr_groups[1]; i < cred->cr_ngroups; i++, gp++)
 142                 if (ino_gid == *gp) {
 143                         if (mode & VEXEC)
 144                                 mask |= S_IXGRP;
 145                         if (mode & VREAD)
 146                                 mask |= S_IRGRP;
 147                         if (mode & VWRITE)
 148                                 mask |= S_IWGRP;
 149                         return ((ino_mode & mask) == mask ? 0 : EACCES);
 150                 }
 151
 152         /* Otherwise, check everyone else. */
 153         if (mode & VEXEC)
 154                 mask |= S_IXOTH;
 155         if (mode & VREAD)
 156                 mask |= S_IROTH;
 157         if (mode & VWRITE)
 158                 mask |= S_IWOTH;
 159         return ((ino_mode & mask) == mask ? 0 : EACCES);
 160 }
 161
 162 int
 163 vop_helper_setattr_flags(u_int32_t *ino_flags, u_int32_t vaflags,
 164                          uid_t uid, struct ucred *cred)
 165 {
 166         int error;
 167
 168         /*
 169          * If uid doesn't match only a privileged user can change the flags
 170          */
 171         if (cred->cr_uid != uid &&
 172             (error = priv_check_cred(cred, PRIV_VFS_SYSFLAGS, 0))) {
 173                 return(error);
 174         }
 175         if (cred->cr_uid == 0 &&
 176             (!jailed(cred)|| jail_chflags_allowed)) {
 177                 if ((*ino_flags & (SF_NOUNLINK|SF_IMMUTABLE|SF_APPEND)) &&
 178                     securelevel > 0)
 179                         return (EPERM);
 180                 *ino_flags = vaflags;
 181         } else {
 182                 if (*ino_flags & (SF_NOUNLINK|SF_IMMUTABLE|SF_APPEND) ||
 183                     (vaflags & UF_SETTABLE) != vaflags)
 184                         return (EPERM);
 185                 *ino_flags &= SF_SETTABLE;
 186                 *ino_flags |= vaflags & UF_SETTABLE;
 187         }
 188         return(0);
 189 }
 190
 191 /*
 192  * This helper function may be used by VFSs to implement UNIX initial
 193  * ownership semantics when creating new objects inside directories.
 194  */
 195 uid_t
 196 vop_helper_create_uid(struct mount *mp, mode_t dmode, uid_t duid,
 197                       struct ucred *cred, mode_t *modep)
 198 {
 199 #ifdef SUIDDIR
 200         if ((mp->mnt_flag & MNT_SUIDDIR) && (dmode & S_ISUID) &&
 201             duid != cred->cr_uid && duid) {
 202                 *modep &= ~07111;
 203                 return(duid);
 204         }
 205 #endif
 206         return(cred->cr_uid);
 207 }
 208
 209 /*
 210  * This helper may be used by VFSs to implement unix chmod semantics.
 211  *
 212  * XXX TEMPORARY chmod override for VCHR devices.  Allow the device to
 213  *               override the uid if the uid is not root.  This is used
 214  *               by pty's to set the owner for the related tty.
 215  *
 216  * XXX REMOVE THE OVERRIDE WHEN DEVFS IS MERGED.
 217  */
 218 int
 219 vop_helper_chmod(struct vnode *vp, mode_t new_mode, struct ucred *cred,
 220                  uid_t cur_uid, gid_t cur_gid, mode_t *cur_modep)
 221 {
 222         int error;
 223
 224         if (cred->cr_uid != cur_uid) {
 225                 error = priv_check_cred(cred, PRIV_VFS_CHMOD, 0);
 226                 if (error)
 227                         return (error);
 228         }
 229         if (cred->cr_uid) {
 230                 if (vp->v_type != VDIR && (*cur_modep & S_ISTXT))
 231                         return (EFTYPE);
 232                 if (!groupmember(cur_gid, cred) && (*cur_modep & S_ISGID))
 233                         return (EPERM);
 234         }
 235         *cur_modep &= ~ALLPERMS;
 236         *cur_modep |= new_mode & ALLPERMS;
 237         return(0);
 238 }
 239
 240 /*
 241  * This helper may be used by VFSs to implement unix chown semantics.
 242  */
 243 int
 244 vop_helper_chown(struct vnode *vp, uid_t new_uid, gid_t new_gid,
 245                  struct ucred *cred,
 246                  uid_t *cur_uidp, gid_t *cur_gidp, mode_t *cur_modep)
 247 {
 248         gid_t ogid;
 249         uid_t ouid;
 250         int error;
 251
 252         if (new_uid == (uid_t)VNOVAL)
 253                 new_uid = *cur_uidp;
 254         if (new_gid == (gid_t)VNOVAL)
 255                 new_gid = *cur_gidp;
 256
 257         /*
 258          * If we don't own the file, are trying to change the owner
 259          * of the file, or are not a member of the target group,
 260          * the caller must be privileged or the call fails.
 261          */
 262         if ((cred->cr_uid != *cur_uidp || new_uid != *cur_uidp ||
 263             (new_gid != *cur_gidp && !(cred->cr_gid == new_gid ||
 264             groupmember(new_gid, cred)))) &&
 265             (error = priv_check_cred(cred, PRIV_VFS_CHOWN, 0))) {
 266                 return (error);
 267         }
 268         ogid = *cur_gidp;
 269         ouid = *cur_uidp;
 270         /* XXX QUOTA CODE */
 271         *cur_uidp = new_uid;
 272         *cur_gidp = new_gid;
 273         /* XXX QUOTA CODE */
 274
 275         /*
 276          * DragonFly clears both SUID and SGID if either the owner or
 277          * group is changed and root isn't doing it.  If root is doing
 278          * it we do not clear SUID/SGID.
 279          */
 280         if (cred->cr_uid != 0 && (ouid != new_uid || ogid != new_gid))
 281                 *cur_modep &= ~(S_ISUID | S_ISGID);
 282         return(0);
 283 }
 284