fs/gfs2/acl.c

   1 /*
   2  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
   3  * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
   4  *
   5  * This copyrighted material is made available to anyone wishing to use,
   6  * modify, copy, or redistribute it subject to the terms and conditions
   7  * of the GNU General Public License version 2.
   8  */
   9
  10 #include <linux/sched.h>
  11 #include <linux/slab.h>
  12 #include <linux/spinlock.h>
  13 #include <linux/completion.h>
  14 #include <linux/buffer_head.h>
  15 #include <linux/xattr.h>
  16 #include <linux/posix_acl.h>
  17 #include <linux/posix_acl_xattr.h>
  18 #include <linux/gfs2_ondisk.h>
  19
  20 #include "gfs2.h"
  21 #include "incore.h"
  22 #include "acl.h"
  23 #include "xattr.h"
  24 #include "glock.h"
  25 #include "inode.h"
  26 #include "meta_io.h"
  27 #include "trans.h"
  28 #include "util.h"
  29
  30 static const char *gfs2_acl_name(int type)
  31 {
  32         switch (type) {
  33         case ACL_TYPE_ACCESS:
  34                 return GFS2_POSIX_ACL_ACCESS;
  35         case ACL_TYPE_DEFAULT:
  36                 return GFS2_POSIX_ACL_DEFAULT;
  37         }
  38         return NULL;
  39 }
  40
  41 static struct posix_acl *gfs2_acl_get(struct gfs2_inode *ip, int type)
  42 {
  43         struct posix_acl *acl;
  44         const char *name;
  45         char *data;
  46         int len;
  47
  48         if (!ip->i_eattr)
  49                 return NULL;
  50
  51         acl = get_cached_acl(&ip->i_inode, type);
  52         if (acl != ACL_NOT_CACHED)
  53                 return acl;
  54
  55         name = gfs2_acl_name(type);
  56         if (name == NULL)
  57                 return ERR_PTR(-EINVAL);
  58
  59         len = gfs2_xattr_acl_get(ip, name, &data);
  60         if (len < 0)
  61                 return ERR_PTR(len);
  62         if (len == 0)
  63                 return NULL;
  64
  65         acl = posix_acl_from_xattr(data, len);
  66         kfree(data);
  67         return acl;
  68 }
  69
  70 /**
  71  * gfs2_check_acl - Check an ACL to see if we're allowed to do something
  72  * @inode: the file we want to do something to
  73  * @mask: what we want to do
  74  *
  75  * Returns: errno
  76  */
  77
  78 int gfs2_check_acl(struct inode *inode, int mask)
  79 {
  80         struct posix_acl *acl;
  81         int error;
  82
  83         acl = gfs2_acl_get(GFS2_I(inode), ACL_TYPE_ACCESS);
  84         if (IS_ERR(acl))
  85                 return PTR_ERR(acl);
  86
  87         if (acl) {
  88                 error = posix_acl_permission(inode, acl, mask);
  89                 posix_acl_release(acl);
  90                 return error;
  91         }
  92
  93         return -EAGAIN;
  94 }
  95
  96 static int gfs2_set_mode(struct inode *inode, mode_t mode)
  97 {
  98         int error = 0;
  99
 100         if (mode != inode->i_mode) {
 101                 struct iattr iattr;
 102
 103                 iattr.ia_valid = ATTR_MODE;
 104                 iattr.ia_mode = mode;
 105
 106                 error = gfs2_setattr_simple(GFS2_I(inode), &iattr);
 107         }
 108
 109         return error;
 110 }
 111
 112 static int gfs2_acl_set(struct inode *inode, int type, struct posix_acl *acl)
 113 {
 114         int error;
 115         int len;
 116         char *data;
 117         const char *name = gfs2_acl_name(type);
 118
 119         BUG_ON(name == NULL);
 120         len = posix_acl_to_xattr(acl, NULL, 0);
 121         if (len == 0)
 122                 return 0;
 123         data = kmalloc(len, GFP_NOFS);
 124         if (data == NULL)
 125                 return -ENOMEM;
 126         error = posix_acl_to_xattr(acl, data, len);
 127         if (error < 0)
 128                 goto out;
 129         error = gfs2_xattr_set(inode, GFS2_EATYPE_SYS, name, data, len, 0);
 130         if (!error)
 131                 set_cached_acl(inode, type, acl);
 132 out:
 133         kfree(data);
 134         return error;
 135 }
 136
 137 int gfs2_acl_create(struct gfs2_inode *dip, struct inode *inode)
 138 {
 139         struct gfs2_sbd *sdp = GFS2_SB(&dip->i_inode);
 140         struct posix_acl *acl, *clone;
 141         mode_t mode = inode->i_mode;
 142         int error = 0;
 143
 144         if (!sdp->sd_args.ar_posix_acl)
 145                 return 0;
 146         if (S_ISLNK(inode->i_mode))
 147                 return 0;
 148
 149         acl = gfs2_acl_get(dip, ACL_TYPE_DEFAULT);
 150         if (IS_ERR(acl))
 151                 return PTR_ERR(acl);
 152         if (!acl) {
 153                 mode &= ~current_umask();
 154                 if (mode != inode->i_mode)
 155                         error = gfs2_set_mode(inode, mode);
 156                 return error;
 157         }
 158
 159         if (S_ISDIR(inode->i_mode)) {
 160                 error = gfs2_acl_set(inode, ACL_TYPE_DEFAULT, acl);
 161                 if (error)
 162                         goto out;
 163         }
 164
 165         clone = posix_acl_clone(acl, GFP_NOFS);
 166         error = -ENOMEM;
 167         if (!clone)
 168                 goto out;
 169         posix_acl_release(acl);
 170         acl = clone;
 171
 172         error = posix_acl_create_masq(acl, &mode);
 173         if (error < 0)
 174                 goto out;
 175         if (error == 0)
 176                 goto munge;
 177
 178         error = gfs2_acl_set(inode, ACL_TYPE_ACCESS, acl);
 179         if (error)
 180                 goto out;
 181 munge:
 182         error = gfs2_set_mode(inode, mode);
 183 out:
 184         posix_acl_release(acl);
 185         return error;
 186 }
 187
 188 int gfs2_acl_chmod(struct gfs2_inode *ip, struct iattr *attr)
 189 {
 190         struct posix_acl *acl, *clone;
 191         char *data;
 192         unsigned int len;
 193         int error;
 194
 195         acl = gfs2_acl_get(ip, ACL_TYPE_ACCESS);
 196         if (IS_ERR(acl))
 197                 return PTR_ERR(acl);
 198         if (!acl)
 199                 return gfs2_setattr_simple(ip, attr);
 200
 201         clone = posix_acl_clone(acl, GFP_NOFS);
 202         error = -ENOMEM;
 203         if (!clone)
 204                 goto out;
 205         posix_acl_release(acl);
 206         acl = clone;
 207
 208         error = posix_acl_chmod_masq(acl, attr->ia_mode);
 209         if (!error) {
 210                 len = posix_acl_to_xattr(acl, NULL, 0);
 211                 data = kmalloc(len, GFP_NOFS);
 212                 error = -ENOMEM;
 213                 if (data == NULL)
 214                         goto out;
 215                 posix_acl_to_xattr(acl, data, len);
 216                 error = gfs2_xattr_acl_chmod(ip, attr, data);
 217                 kfree(data);
 218                 set_cached_acl(&ip->i_inode, ACL_TYPE_ACCESS, acl);
 219         }
 220
 221 out:
 222         posix_acl_release(acl);
 223         return error;
 224 }
 225
 226 static int gfs2_acl_type(const char *name)
 227 {
 228         if (strcmp(name, GFS2_POSIX_ACL_ACCESS) == 0)
 229                 return ACL_TYPE_ACCESS;
 230         if (strcmp(name, GFS2_POSIX_ACL_DEFAULT) == 0)
 231                 return ACL_TYPE_DEFAULT;
 232         return -EINVAL;
 233 }
 234
 235 static int gfs2_xattr_system_get(struct inode *inode, const char *name,
 236                                  void *buffer, size_t size)
 237 {
 238         struct posix_acl *acl;
 239         int type;
 240         int error;
 241
 242         type = gfs2_acl_type(name);
 243         if (type < 0)
 244                 return type;
 245
 246         acl = gfs2_acl_get(GFS2_I(inode), type);
 247         if (IS_ERR(acl))
 248                 return PTR_ERR(acl);
 249         if (acl == NULL)
 250                 return -ENODATA;
 251
 252         error = posix_acl_to_xattr(acl, buffer, size);
 253         posix_acl_release(acl);
 254
 255         return error;
 256 }
 257
 258 static int gfs2_xattr_system_set(struct inode *inode, const char *name,
 259                                  const void *value, size_t size, int flags)
 260 {
 261         struct gfs2_sbd *sdp = GFS2_SB(inode);
 262         struct posix_acl *acl = NULL;
 263         int error = 0, type;
 264
 265         if (!sdp->sd_args.ar_posix_acl)
 266                 return -EOPNOTSUPP;
 267
 268         type = gfs2_acl_type(name);
 269         if (type < 0)
 270                 return type;
 271         if (flags & XATTR_CREATE)
 272                 return -EINVAL;
 273         if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
 274                 return value ? -EACCES : 0;
 275         if ((current_fsuid() != inode->i_uid) && !capable(CAP_FOWNER))
 276                 return -EPERM;
 277         if (S_ISLNK(inode->i_mode))
 278                 return -EOPNOTSUPP;
 279
 280         if (!value)
 281                 goto set_acl;
 282
 283         acl = posix_acl_from_xattr(value, size);
 284         if (!acl) {
 285                 /*
 286                  * acl_set_file(3) may request that we set default ACLs with
 287                  * zero length -- defend (gracefully) against that here.
 288                  */
 289                 goto out;
 290         }
 291         if (IS_ERR(acl)) {
 292                 error = PTR_ERR(acl);
 293                 goto out;
 294         }
 295
 296         error = posix_acl_valid(acl);
 297         if (error)
 298                 goto out_release;
 299
 300         error = -EINVAL;
 301         if (acl->a_count > GFS2_ACL_MAX_ENTRIES)
 302                 goto out_release;
 303
 304         if (type == ACL_TYPE_ACCESS) {
 305                 mode_t mode = inode->i_mode;
 306                 error = posix_acl_equiv_mode(acl, &mode);
 307
 308                 if (error <= 0) {
 309                         posix_acl_release(acl);
 310                         acl = NULL;
 311
 312                         if (error < 0)
 313                                 return error;
 314                 }
 315
 316                 error = gfs2_set_mode(inode, mode);
 317                 if (error)
 318                         goto out_release;
 319         }
 320
 321 set_acl:
 322         error = gfs2_xattr_set(inode, GFS2_EATYPE_SYS, name, value, size, 0);
 323         if (!error) {
 324                 if (acl)
 325                         set_cached_acl(inode, type, acl);
 326                 else
 327                         forget_cached_acl(inode, type);
 328         }
 329 out_release:
 330         posix_acl_release(acl);
 331 out:
 332         return error;
 333 }
 334
 335 struct xattr_handler gfs2_xattr_system_handler = {
 336         .prefix = XATTR_SYSTEM_PREFIX,
 337         .get    = gfs2_xattr_system_get,
 338         .set    = gfs2_xattr_system_set,
 339 };
 340