fs/9p/acl.c

   1 /*
   2  * Copyright IBM Corporation, 2010
   3  * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of version 2.1 of the GNU Lesser General Public License
   7  * as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  12  *
  13  */
  14
  15 #include <linux/module.h>
  16 #include <linux/fs.h>
  17 #include <net/9p/9p.h>
  18 #include <net/9p/client.h>
  19 #include <linux/slab.h>
  20 #include <linux/sched.h>
  21 #include <linux/posix_acl_xattr.h>
  22 #include "xattr.h"
  23 #include "acl.h"
  24 #include "v9fs_vfs.h"
  25 #include "v9fs.h"
  26
  27 static struct posix_acl *__v9fs_get_acl(struct p9_fid *fid, char *name)
  28 {
  29         ssize_t size;
  30         void *value = NULL;
  31         struct posix_acl *acl = NULL;
  32
  33         size = v9fs_fid_xattr_get(fid, name, NULL, 0);
  34         if (size > 0) {
  35                 value = kzalloc(size, GFP_NOFS);
  36                 if (!value)
  37                         return ERR_PTR(-ENOMEM);
  38                 size = v9fs_fid_xattr_get(fid, name, value, size);
  39                 if (size > 0) {
  40                         acl = posix_acl_from_xattr(value, size);
  41                         if (IS_ERR(acl))
  42                                 goto err_out;
  43                 }
  44         } else if (size == -ENODATA || size == 0 ||
  45                    size == -ENOSYS || size == -EOPNOTSUPP) {
  46                 acl = NULL;
  47         } else
  48                 acl = ERR_PTR(-EIO);
  49
  50 err_out:
  51         kfree(value);
  52         return acl;
  53 }
  54
  55 int v9fs_get_acl(struct inode *inode, struct p9_fid *fid)
  56 {
  57         int retval = 0;
  58         struct posix_acl *pacl, *dacl;
  59         struct v9fs_session_info *v9ses;
  60
  61         v9ses = v9fs_inode2v9ses(inode);
  62         if ((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT) {
  63                 set_cached_acl(inode, ACL_TYPE_DEFAULT, NULL);
  64                 set_cached_acl(inode, ACL_TYPE_ACCESS, NULL);
  65                 return 0;
  66         }
  67         /* get the default/access acl values and cache them */
  68         dacl = __v9fs_get_acl(fid, POSIX_ACL_XATTR_DEFAULT);
  69         pacl = __v9fs_get_acl(fid, POSIX_ACL_XATTR_ACCESS);
  70
  71         if (!IS_ERR(dacl) && !IS_ERR(pacl)) {
  72                 set_cached_acl(inode, ACL_TYPE_DEFAULT, dacl);
  73                 set_cached_acl(inode, ACL_TYPE_ACCESS, pacl);
  74                 posix_acl_release(dacl);
  75                 posix_acl_release(pacl);
  76         } else
  77                 retval = -EIO;
  78
  79         return retval;
  80 }
  81
  82 static struct posix_acl *v9fs_get_cached_acl(struct inode *inode, int type)
  83 {
  84         struct posix_acl *acl;
  85         /*
  86          * 9p Always cache the acl value when
  87          * instantiating the inode (v9fs_inode_from_fid)
  88          */
  89         acl = get_cached_acl(inode, type);
  90         BUG_ON(acl == ACL_NOT_CACHED);
  91         return acl;
  92 }
  93
  94 int v9fs_check_acl(struct inode *inode, int mask, unsigned int flags)
  95 {
  96         struct posix_acl *acl;
  97         struct v9fs_session_info *v9ses;
  98
  99         if (flags & IPERM_FLAG_RCU)
 100                 return -ECHILD;
 101
 102         v9ses = v9fs_inode2v9ses(inode);
 103         if ((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT) {
 104                 /*
 105                  * On access = client mode get the acl
 106                  * values from the server
 107                  */
 108                 return 0;
 109         }
 110         acl = v9fs_get_cached_acl(inode, ACL_TYPE_ACCESS);
 111
 112         if (IS_ERR(acl))
 113                 return PTR_ERR(acl);
 114         if (acl) {
 115                 int error = posix_acl_permission(inode, acl, mask);
 116                 posix_acl_release(acl);
 117                 return error;
 118         }
 119         return -EAGAIN;
 120 }
 121
 122 static int v9fs_set_acl(struct dentry *dentry, int type, struct posix_acl *acl)
 123 {
 124         int retval;
 125         char *name;
 126         size_t size;
 127         void *buffer;
 128         struct inode *inode = dentry->d_inode;
 129
 130         set_cached_acl(inode, type, acl);
 131         /* Set a setxattr request to server */
 132         size = posix_acl_xattr_size(acl->a_count);
 133         buffer = kmalloc(size, GFP_KERNEL);
 134         if (!buffer)
 135                 return -ENOMEM;
 136         retval = posix_acl_to_xattr(acl, buffer, size);
 137         if (retval < 0)
 138                 goto err_free_out;
 139         switch (type) {
 140         case ACL_TYPE_ACCESS:
 141                 name = POSIX_ACL_XATTR_ACCESS;
 142                 break;
 143         case ACL_TYPE_DEFAULT:
 144                 name = POSIX_ACL_XATTR_DEFAULT;
 145                 break;
 146         default:
 147                 BUG();
 148         }
 149         retval = v9fs_xattr_set(dentry, name, buffer, size, 0);
 150 err_free_out:
 151         kfree(buffer);
 152         return retval;
 153 }
 154
 155 int v9fs_acl_chmod(struct dentry *dentry)
 156 {
 157         int retval = 0;
 158         struct posix_acl *acl, *clone;
 159         struct inode *inode = dentry->d_inode;
 160
 161         if (S_ISLNK(inode->i_mode))
 162                 return -EOPNOTSUPP;
 163         acl = v9fs_get_cached_acl(inode, ACL_TYPE_ACCESS);
 164         if (acl) {
 165                 clone = posix_acl_clone(acl, GFP_KERNEL);
 166                 posix_acl_release(acl);
 167                 if (!clone)
 168                         return -ENOMEM;
 169                 retval = posix_acl_chmod_masq(clone, inode->i_mode);
 170                 if (!retval)
 171                         retval = v9fs_set_acl(dentry, ACL_TYPE_ACCESS, clone);
 172                 posix_acl_release(clone);
 173         }
 174         return retval;
 175 }
 176
 177 int v9fs_set_create_acl(struct dentry *dentry,
 178                         struct posix_acl *dpacl, struct posix_acl *pacl)
 179 {
 180         if (dpacl)
 181                 v9fs_set_acl(dentry, ACL_TYPE_DEFAULT, dpacl);
 182         if (pacl)
 183                 v9fs_set_acl(dentry, ACL_TYPE_ACCESS, pacl);
 184         posix_acl_release(dpacl);
 185         posix_acl_release(pacl);
 186         return 0;
 187 }
 188
 189 int v9fs_acl_mode(struct inode *dir, mode_t *modep,
 190                   struct posix_acl **dpacl, struct posix_acl **pacl)
 191 {
 192         int retval = 0;
 193         mode_t mode = *modep;
 194         struct posix_acl *acl = NULL;
 195
 196         if (!S_ISLNK(mode)) {
 197                 acl = v9fs_get_cached_acl(dir, ACL_TYPE_DEFAULT);
 198                 if (IS_ERR(acl))
 199                         return PTR_ERR(acl);
 200                 if (!acl)
 201                         mode &= ~current_umask();
 202         }
 203         if (acl) {
 204                 struct posix_acl *clone;
 205
 206                 if (S_ISDIR(mode))
 207                         *dpacl = acl;
 208                 clone = posix_acl_clone(acl, GFP_NOFS);
 209                 retval = -ENOMEM;
 210                 if (!clone)
 211                         goto cleanup;
 212
 213                 retval = posix_acl_create_masq(clone, &mode);
 214                 if (retval < 0) {
 215                         posix_acl_release(clone);
 216                         goto cleanup;
 217                 }
 218                 if (retval > 0)
 219                         *pacl = clone;
 220         }
 221         *modep  = mode;
 222         return 0;
 223 cleanup:
 224         posix_acl_release(acl);
 225         return retval;
 226
 227 }
 228
 229 static int v9fs_remote_get_acl(struct dentry *dentry, const char *name,
 230                                void *buffer, size_t size, int type)
 231 {
 232         char *full_name;
 233
 234         switch (type) {
 235         case ACL_TYPE_ACCESS:
 236                 full_name =  POSIX_ACL_XATTR_ACCESS;
 237                 break;
 238         case ACL_TYPE_DEFAULT:
 239                 full_name = POSIX_ACL_XATTR_DEFAULT;
 240                 break;
 241         default:
 242                 BUG();
 243         }
 244         return v9fs_xattr_get(dentry, full_name, buffer, size);
 245 }
 246
 247 static int v9fs_xattr_get_acl(struct dentry *dentry, const char *name,
 248                               void *buffer, size_t size, int type)
 249 {
 250         struct v9fs_session_info *v9ses;
 251         struct posix_acl *acl;
 252         int error;
 253
 254         if (strcmp(name, "") != 0)
 255                 return -EINVAL;
 256
 257         v9ses = v9fs_inode2v9ses(dentry->d_inode);
 258         /*
 259          * We allow set/get/list of acl when access=client is not specified
 260          */
 261         if ((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT)
 262                 return v9fs_remote_get_acl(dentry, name, buffer, size, type);
 263
 264         acl = v9fs_get_cached_acl(dentry->d_inode, type);
 265         if (IS_ERR(acl))
 266                 return PTR_ERR(acl);
 267         if (acl == NULL)
 268                 return -ENODATA;
 269         error = posix_acl_to_xattr(acl, buffer, size);
 270         posix_acl_release(acl);
 271
 272         return error;
 273 }
 274
 275 static int v9fs_remote_set_acl(struct dentry *dentry, const char *name,
 276                               const void *value, size_t size,
 277                               int flags, int type)
 278 {
 279         char *full_name;
 280
 281         switch (type) {
 282         case ACL_TYPE_ACCESS:
 283                 full_name =  POSIX_ACL_XATTR_ACCESS;
 284                 break;
 285         case ACL_TYPE_DEFAULT:
 286                 full_name = POSIX_ACL_XATTR_DEFAULT;
 287                 break;
 288         default:
 289                 BUG();
 290         }
 291         return v9fs_xattr_set(dentry, full_name, value, size, flags);
 292 }
 293
 294
 295 static int v9fs_xattr_set_acl(struct dentry *dentry, const char *name,
 296                               const void *value, size_t size,
 297                               int flags, int type)
 298 {
 299         int retval;
 300         struct posix_acl *acl;
 301         struct v9fs_session_info *v9ses;
 302         struct inode *inode = dentry->d_inode;
 303
 304         if (strcmp(name, "") != 0)
 305                 return -EINVAL;
 306
 307         v9ses = v9fs_inode2v9ses(dentry->d_inode);
 308         /*
 309          * set the attribute on the remote. Without even looking at the
 310          * xattr value. We leave it to the server to validate
 311          */
 312         if ((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT)
 313                 return v9fs_remote_set_acl(dentry, name,
 314                                            value, size, flags, type);
 315
 316         if (S_ISLNK(inode->i_mode))
 317                 return -EOPNOTSUPP;
 318         if (!is_owner_or_cap(inode))
 319                 return -EPERM;
 320         if (value) {
 321                 /* update the cached acl value */
 322                 acl = posix_acl_from_xattr(value, size);
 323                 if (IS_ERR(acl))
 324                         return PTR_ERR(acl);
 325                 else if (acl) {
 326                         retval = posix_acl_valid(acl);
 327                         if (retval)
 328                                 goto err_out;
 329                 }
 330         } else
 331                 acl = NULL;
 332
 333         switch (type) {
 334         case ACL_TYPE_ACCESS:
 335                 name = POSIX_ACL_XATTR_ACCESS;
 336                 if (acl) {
 337                         mode_t mode = inode->i_mode;
 338                         retval = posix_acl_equiv_mode(acl, &mode);
 339                         if (retval < 0)
 340                                 goto err_out;
 341                         else {
 342                                 struct iattr iattr;
 343                                 if (retval == 0) {
 344                                         /*
 345                                          * ACL can be represented
 346                                          * by the mode bits. So don't
 347                                          * update ACL.
 348                                          */
 349                                         acl = NULL;
 350                                         value = NULL;
 351                                         size = 0;
 352                                 }
 353                                 /* Updte the mode bits */
 354                                 iattr.ia_mode = ((mode & S_IALLUGO) |
 355                                                  (inode->i_mode & ~S_IALLUGO));
 356                                 iattr.ia_valid = ATTR_MODE;
 357                                 /* FIXME should we update ctime ?
 358                                  * What is the following setxattr update the
 359                                  * mode ?
 360                                  */
 361                                 v9fs_vfs_setattr_dotl(dentry, &iattr);
 362                         }
 363                 }
 364                 break;
 365         case ACL_TYPE_DEFAULT:
 366                 name = POSIX_ACL_XATTR_DEFAULT;
 367                 if (!S_ISDIR(inode->i_mode)) {
 368                         retval = acl ? -EINVAL : 0;
 369                         goto err_out;
 370                 }
 371                 break;
 372         default:
 373                 BUG();
 374         }
 375         retval = v9fs_xattr_set(dentry, name, value, size, flags);
 376         if (!retval)
 377                 set_cached_acl(inode, type, acl);
 378 err_out:
 379         posix_acl_release(acl);
 380         return retval;
 381 }
 382
 383 const struct xattr_handler v9fs_xattr_acl_access_handler = {
 384         .prefix = POSIX_ACL_XATTR_ACCESS,
 385         .flags  = ACL_TYPE_ACCESS,
 386         .get    = v9fs_xattr_get_acl,
 387         .set    = v9fs_xattr_set_acl,
 388 };
 389
 390 const struct xattr_handler v9fs_xattr_acl_default_handler = {
 391         .prefix = POSIX_ACL_XATTR_DEFAULT,
 392         .flags  = ACL_TYPE_DEFAULT,
 393         .get    = v9fs_xattr_get_acl,
 394         .set    = v9fs_xattr_set_acl,
 395 };