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, unsigned int flags)
  79 {
  80         struct posix_acl *acl;
  81         int error;
  82
  83         if (flags & IPERM_FLAG_RCU)
  84                 return -ECHILD;
  85
  86         acl = gfs2_acl_get(GFS2_I(inode), ACL_TYPE_ACCESS);
  87         if (IS_ERR(acl))
  88                 return PTR_ERR(acl);
  89
  90         if (acl) {
  91                 error = posix_acl_permission(inode, acl, mask);
  92                 posix_acl_release(acl);
  93                 return error;
  94         }
  95
  96         return -EAGAIN;
  97 }
  98
  99 static int gfs2_set_mode(struct inode *inode, mode_t mode)
 100 {
 101         int error = 0;
 102
 103         if (mode != inode->i_mode) {
 104                 struct iattr iattr;
 105
 106                 iattr.ia_valid = ATTR_MODE;
 107                 iattr.ia_mode = mode;
 108
 109                 error = gfs2_setattr_simple(GFS2_I(inode), &iattr);
 110         }
 111
 112         return error;
 113 }
 114
 115 static int gfs2_acl_set(struct inode *inode, int type, struct posix_acl *acl)
 116 {
 117         int error;
 118         int len;
 119         char *data;
 120         const char *name = gfs2_acl_name(type);
 121
 122         BUG_ON(name == NULL);
 123         len = posix_acl_to_xattr(acl, NULL, 0);
 124         if (len == 0)
 125                 return 0;
 126         data = kmalloc(len, GFP_NOFS);
 127         if (data == NULL)
 128                 return -ENOMEM;
 129         error = posix_acl_to_xattr(acl, data, len);
 130         if (error < 0)
 131                 goto out;
 132         error = __gfs2_xattr_set(inode, name, data, len, 0, GFS2_EATYPE_SYS);
 133         if (!error)
 134                 set_cached_acl(inode, type, acl);
 135 out:
 136         kfree(data);
 137         return error;
 138 }
 139
 140 int gfs2_acl_create(struct gfs2_inode *dip, struct inode *inode)
 141 {
 142         struct gfs2_sbd *sdp = GFS2_SB(&dip->i_inode);
 143         struct posix_acl *acl, *clone;
 144         mode_t mode = inode->i_mode;
 145         int error = 0;
 146
 147         if (!sdp->sd_args.ar_posix_acl)
 148                 return 0;
 149         if (S_ISLNK(inode->i_mode))
 150                 return 0;
 151
 152         acl = gfs2_acl_get(dip, ACL_TYPE_DEFAULT);
 153         if (IS_ERR(acl))
 154                 return PTR_ERR(acl);
 155         if (!acl) {
 156                 mode &= ~current_umask();
 157                 if (mode != inode->i_mode)
 158                         error = gfs2_set_mode(inode, mode);
 159                 return error;
 160         }
 161
 162         if (S_ISDIR(inode->i_mode)) {
 163                 error = gfs2_acl_set(inode, ACL_TYPE_DEFAULT, acl);
 164                 if (error)
 165                         goto out;
 166         }
 167
 168         clone = posix_acl_clone(acl, GFP_NOFS);
 169         error = -ENOMEM;
 170         if (!clone)
 171                 goto out;
 172         posix_acl_release(acl);
 173         acl = clone;
 174
 175         error = posix_acl_create_masq(acl, &mode);
 176         if (error < 0)
 177                 goto out;
 178         if (error == 0)
 179                 goto munge;
 180
 181         error = gfs2_acl_set(inode, ACL_TYPE_ACCESS, acl);
 182         if (error)
 183                 goto out;
 184 munge:
 185         error = gfs2_set_mode(inode, mode);
 186 out:
 187         posix_acl_release(acl);
 188         return error;
 189 }
 190
 191 int gfs2_acl_chmod(struct gfs2_inode *ip, struct iattr *attr)
 192 {
 193         struct posix_acl *acl, *clone;
 194         char *data;
 195         unsigned int len;
 196         int error;
 197
 198         acl = gfs2_acl_get(ip, ACL_TYPE_ACCESS);
 199         if (IS_ERR(acl))
 200                 return PTR_ERR(acl);
 201         if (!acl)
 202                 return gfs2_setattr_simple(ip, attr);
 203
 204         clone = posix_acl_clone(acl, GFP_NOFS);
 205         error = -ENOMEM;
 206         if (!clone)
 207                 goto out;
 208         posix_acl_release(acl);
 209         acl = clone;
 210
 211         error = posix_acl_chmod_masq(acl, attr->ia_mode);
 212         if (!error) {
 213                 len = posix_acl_to_xattr(acl, NULL, 0);
 214                 data = kmalloc(len, GFP_NOFS);
 215                 error = -ENOMEM;
 216                 if (data == NULL)
 217                         goto out;
 218                 posix_acl_to_xattr(acl, data, len);
 219                 error = gfs2_xattr_acl_chmod(ip, attr, data);
 220                 kfree(data);
 221                 set_cached_acl(&ip->i_inode, ACL_TYPE_ACCESS, acl);
 222         }
 223
 224 out:
 225         posix_acl_release(acl);
 226         return error;
 227 }
 228
 229 static int gfs2_acl_type(const char *name)
 230 {
 231         if (strcmp(name, GFS2_POSIX_ACL_ACCESS) == 0)
 232                 return ACL_TYPE_ACCESS;
 233         if (strcmp(name, GFS2_POSIX_ACL_DEFAULT) == 0)
 234                 return ACL_TYPE_DEFAULT;
 235         return -EINVAL;
 236 }
 237
 238 static int gfs2_xattr_system_get(struct dentry *dentry, const char *name,
 239                                  void *buffer, size_t size, int xtype)
 240 {
 241         struct inode *inode = dentry->d_inode;
 242         struct gfs2_sbd *sdp = GFS2_SB(inode);
 243         struct posix_acl *acl;
 244         int type;
 245         int error;
 246
 247         if (!sdp->sd_args.ar_posix_acl)
 248                 return -EOPNOTSUPP;
 249
 250         type = gfs2_acl_type(name);
 251         if (type < 0)
 252                 return type;
 253
 254         acl = gfs2_acl_get(GFS2_I(inode), type);
 255         if (IS_ERR(acl))
 256                 return PTR_ERR(acl);
 257         if (acl == NULL)
 258                 return -ENODATA;
 259
 260         error = posix_acl_to_xattr(acl, buffer, size);
 261         posix_acl_release(acl);
 262
 263         return error;
 264 }
 265
 266 static int gfs2_xattr_system_set(struct dentry *dentry, const char *name,
 267                                  const void *value, size_t size, int flags,
 268                                  int xtype)
 269 {
 270         struct inode *inode = dentry->d_inode;
 271         struct gfs2_sbd *sdp = GFS2_SB(inode);
 272         struct posix_acl *acl = NULL;
 273         int error = 0, type;
 274
 275         if (!sdp->sd_args.ar_posix_acl)
 276                 return -EOPNOTSUPP;
 277
 278         type = gfs2_acl_type(name);
 279         if (type < 0)
 280                 return type;
 281         if (flags & XATTR_CREATE)
 282                 return -EINVAL;
 283         if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
 284                 return value ? -EACCES : 0;
 285         if ((current_fsuid() != inode->i_uid) && !capable(CAP_FOWNER))
 286                 return -EPERM;
 287         if (S_ISLNK(inode->i_mode))
 288                 return -EOPNOTSUPP;
 289
 290         if (!value)
 291                 goto set_acl;
 292
 293         acl = posix_acl_from_xattr(value, size);
 294         if (!acl) {
 295                 /*
 296                  * acl_set_file(3) may request that we set default ACLs with
 297                  * zero length -- defend (gracefully) against that here.
 298                  */
 299                 goto out;
 300         }
 301         if (IS_ERR(acl)) {
 302                 error = PTR_ERR(acl);
 303                 goto out;
 304         }
 305
 306         error = posix_acl_valid(acl);
 307         if (error)
 308                 goto out_release;
 309
 310         error = -EINVAL;
 311         if (acl->a_count > GFS2_ACL_MAX_ENTRIES)
 312                 goto out_release;
 313
 314         if (type == ACL_TYPE_ACCESS) {
 315                 mode_t mode = inode->i_mode;
 316                 error = posix_acl_equiv_mode(acl, &mode);
 317
 318                 if (error <= 0) {
 319                         posix_acl_release(acl);
 320                         acl = NULL;
 321
 322                         if (error < 0)
 323                                 return error;
 324                 }
 325
 326                 error = gfs2_set_mode(inode, mode);
 327                 if (error)
 328                         goto out_release;
 329         }
 330
 331 set_acl:
 332         error = __gfs2_xattr_set(inode, name, value, size, 0, GFS2_EATYPE_SYS);
 333         if (!error) {
 334                 if (acl)
 335                         set_cached_acl(inode, type, acl);
 336                 else
 337                         forget_cached_acl(inode, type);
 338         }
 339 out_release:
 340         posix_acl_release(acl);
 341 out:
 342         return error;
 343 }
 344
 345 const struct xattr_handler gfs2_xattr_system_handler = {
 346         .prefix = XATTR_SYSTEM_PREFIX,
 347         .flags  = GFS2_EATYPE_SYS,
 348         .get    = gfs2_xattr_system_get,
 349         .set    = gfs2_xattr_system_set,
 350 };
 351