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.h"
  25 #include "v9fs_vfs.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                         ((v9ses->flags & V9FS_ACL_MASK) != V9FS_POSIX_ACL)) {
  64                 set_cached_acl(inode, ACL_TYPE_DEFAULT, NULL);
  65                 set_cached_acl(inode, ACL_TYPE_ACCESS, NULL);
  66                 return 0;
  67         }
  68         /* get the default/access acl values and cache them */
  69         dacl = __v9fs_get_acl(fid, POSIX_ACL_XATTR_DEFAULT);
  70         pacl = __v9fs_get_acl(fid, POSIX_ACL_XATTR_ACCESS);
  71
  72         if (!IS_ERR(dacl) && !IS_ERR(pacl)) {
  73                 set_cached_acl(inode, ACL_TYPE_DEFAULT, dacl);
  74                 set_cached_acl(inode, ACL_TYPE_ACCESS, pacl);
  75         } else
  76                 retval = -EIO;
  77
  78         if (!IS_ERR(dacl))
  79                 posix_acl_release(dacl);
  80
  81         if (!IS_ERR(pacl))
  82                 posix_acl_release(pacl);
  83
  84         return retval;
  85 }
  86
  87 static struct posix_acl *v9fs_get_cached_acl(struct inode *inode, int type)
  88 {
  89         struct posix_acl *acl;
  90         /*
  91          * 9p Always cache the acl value when
  92          * instantiating the inode (v9fs_inode_from_fid)
  93          */
  94         acl = get_cached_acl(inode, type);
  95         BUG_ON(acl == ACL_NOT_CACHED);
  96         return acl;
  97 }
  98
  99 int v9fs_check_acl(struct inode *inode, int mask, unsigned int flags)
 100 {
 101         struct posix_acl *acl;
 102         struct v9fs_session_info *v9ses;
 103
 104         if (flags & IPERM_FLAG_RCU)
 105                 return -ECHILD;
 106
 107         v9ses = v9fs_inode2v9ses(inode);
 108         if (((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT) ||
 109                         ((v9ses->flags & V9FS_ACL_MASK) != V9FS_POSIX_ACL)) {
 110                 /*
 111                  * On access = client  and acl = on mode get the acl
 112                  * values from the server
 113                  */
 114                 return 0;
 115         }
 116         acl = v9fs_get_cached_acl(inode, ACL_TYPE_ACCESS);
 117
 118         if (IS_ERR(acl))
 119                 return PTR_ERR(acl);
 120         if (acl) {
 121                 int error = posix_acl_permission(inode, acl, mask);
 122                 posix_acl_release(acl);
 123                 return error;
 124         }
 125         return -EAGAIN;
 126 }
 127
 128 static int v9fs_set_acl(struct dentry *dentry, int type, struct posix_acl *acl)
 129 {
 130         int retval;
 131         char *name;
 132         size_t size;
 133         void *buffer;
 134         struct inode *inode = dentry->d_inode;
 135
 136         set_cached_acl(inode, type, acl);
 137
 138         if (!acl)
 139                 return 0;
 140
 141         /* Set a setxattr request to server */
 142         size = posix_acl_xattr_size(acl->a_count);
 143         buffer = kmalloc(size, GFP_KERNEL);
 144         if (!buffer)
 145                 return -ENOMEM;
 146         retval = posix_acl_to_xattr(acl, buffer, size);
 147         if (retval < 0)
 148                 goto err_free_out;
 149         switch (type) {
 150         case ACL_TYPE_ACCESS:
 151                 name = POSIX_ACL_XATTR_ACCESS;
 152                 break;
 153         case ACL_TYPE_DEFAULT:
 154                 name = POSIX_ACL_XATTR_DEFAULT;
 155                 break;
 156         default:
 157                 BUG();
 158         }
 159         retval = v9fs_xattr_set(dentry, name, buffer, size, 0);
 160 err_free_out:
 161         kfree(buffer);
 162         return retval;
 163 }
 164
 165 int v9fs_acl_chmod(struct dentry *dentry)
 166 {
 167         int retval = 0;
 168         struct posix_acl *acl, *clone;
 169         struct inode *inode = dentry->d_inode;
 170
 171         if (S_ISLNK(inode->i_mode))
 172                 return -EOPNOTSUPP;
 173         acl = v9fs_get_cached_acl(inode, ACL_TYPE_ACCESS);
 174         if (acl) {
 175                 clone = posix_acl_clone(acl, GFP_KERNEL);
 176                 posix_acl_release(acl);
 177                 if (!clone)
 178                         return -ENOMEM;
 179                 retval = posix_acl_chmod_masq(clone, inode->i_mode);
 180                 if (!retval)
 181                         retval = v9fs_set_acl(dentry, ACL_TYPE_ACCESS, clone);
 182                 posix_acl_release(clone);
 183         }
 184         return retval;
 185 }
 186
 187 int v9fs_set_create_acl(struct dentry *dentry,
 188                         struct posix_acl **dpacl, struct posix_acl **pacl)
 189 {
 190         if (dentry) {
 191                 v9fs_set_acl(dentry, ACL_TYPE_DEFAULT, *dpacl);
 192                 v9fs_set_acl(dentry, ACL_TYPE_ACCESS, *pacl);
 193         }
 194         posix_acl_release(*dpacl);
 195         posix_acl_release(*pacl);
 196         *dpacl = *pacl = NULL;
 197         return 0;
 198 }
 199
 200 int v9fs_acl_mode(struct inode *dir, mode_t *modep,
 201                   struct posix_acl **dpacl, struct posix_acl **pacl)
 202 {
 203         int retval = 0;
 204         mode_t mode = *modep;
 205         struct posix_acl *acl = NULL;
 206
 207         if (!S_ISLNK(mode)) {
 208                 acl = v9fs_get_cached_acl(dir, ACL_TYPE_DEFAULT);
 209                 if (IS_ERR(acl))
 210                         return PTR_ERR(acl);
 211                 if (!acl)
 212                         mode &= ~current_umask();
 213         }
 214         if (acl) {
 215                 struct posix_acl *clone;
 216
 217                 if (S_ISDIR(mode))
 218                         *dpacl = posix_acl_dup(acl);
 219                 clone = posix_acl_clone(acl, GFP_NOFS);
 220                 posix_acl_release(acl);
 221                 if (!clone)
 222                         return -ENOMEM;
 223
 224                 retval = posix_acl_create_masq(clone, &mode);
 225                 if (retval < 0) {
 226                         posix_acl_release(clone);
 227                         goto cleanup;
 228                 }
 229                 if (retval > 0)
 230                         *pacl = clone;
 231                 else
 232                         posix_acl_release(clone);
 233         }
 234         *modep  = mode;
 235         return 0;
 236 cleanup:
 237         return retval;
 238
 239 }
 240
 241 static int v9fs_remote_get_acl(struct dentry *dentry, const char *name,
 242                                void *buffer, size_t size, int type)
 243 {
 244         char *full_name;
 245
 246         switch (type) {
 247         case ACL_TYPE_ACCESS:
 248                 full_name =  POSIX_ACL_XATTR_ACCESS;
 249                 break;
 250         case ACL_TYPE_DEFAULT:
 251                 full_name = POSIX_ACL_XATTR_DEFAULT;
 252                 break;
 253         default:
 254                 BUG();
 255         }
 256         return v9fs_xattr_get(dentry, full_name, buffer, size);
 257 }
 258
 259 static int v9fs_xattr_get_acl(struct dentry *dentry, const char *name,
 260                               void *buffer, size_t size, int type)
 261 {
 262         struct v9fs_session_info *v9ses;
 263         struct posix_acl *acl;
 264         int error;
 265
 266         if (strcmp(name, "") != 0)
 267                 return -EINVAL;
 268
 269         v9ses = v9fs_dentry2v9ses(dentry);
 270         /*
 271          * We allow set/get/list of acl when access=client is not specified
 272          */
 273         if ((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT)
 274                 return v9fs_remote_get_acl(dentry, name, buffer, size, type);
 275
 276         acl = v9fs_get_cached_acl(dentry->d_inode, type);
 277         if (IS_ERR(acl))
 278                 return PTR_ERR(acl);
 279         if (acl == NULL)
 280                 return -ENODATA;
 281         error = posix_acl_to_xattr(acl, buffer, size);
 282         posix_acl_release(acl);
 283
 284         return error;
 285 }
 286
 287 static int v9fs_remote_set_acl(struct dentry *dentry, const char *name,
 288                               const void *value, size_t size,
 289                               int flags, int type)
 290 {
 291         char *full_name;
 292
 293         switch (type) {
 294         case ACL_TYPE_ACCESS:
 295                 full_name =  POSIX_ACL_XATTR_ACCESS;
 296                 break;
 297         case ACL_TYPE_DEFAULT:
 298                 full_name = POSIX_ACL_XATTR_DEFAULT;
 299                 break;
 300         default:
 301                 BUG();
 302         }
 303         return v9fs_xattr_set(dentry, full_name, value, size, flags);
 304 }
 305
 306
 307 static int v9fs_xattr_set_acl(struct dentry *dentry, const char *name,
 308                               const void *value, size_t size,
 309                               int flags, int type)
 310 {
 311         int retval;
 312         struct posix_acl *acl;
 313         struct v9fs_session_info *v9ses;
 314         struct inode *inode = dentry->d_inode;
 315
 316         if (strcmp(name, "") != 0)
 317                 return -EINVAL;
 318
 319         v9ses = v9fs_dentry2v9ses(dentry);
 320         /*
 321          * set the attribute on the remote. Without even looking at the
 322          * xattr value. We leave it to the server to validate
 323          */
 324         if ((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT)
 325                 return v9fs_remote_set_acl(dentry, name,
 326                                            value, size, flags, type);
 327
 328         if (S_ISLNK(inode->i_mode))
 329                 return -EOPNOTSUPP;
 330         if (!inode_owner_or_capable(inode))
 331                 return -EPERM;
 332         if (value) {
 333                 /* update the cached acl value */
 334                 acl = posix_acl_from_xattr(value, size);
 335                 if (IS_ERR(acl))
 336                         return PTR_ERR(acl);
 337                 else if (acl) {
 338                         retval = posix_acl_valid(acl);
 339                         if (retval)
 340                                 goto err_out;
 341                 }
 342         } else
 343                 acl = NULL;
 344
 345         switch (type) {
 346         case ACL_TYPE_ACCESS:
 347                 name = POSIX_ACL_XATTR_ACCESS;
 348                 if (acl) {
 349                         mode_t mode = inode->i_mode;
 350                         retval = posix_acl_equiv_mode(acl, &mode);
 351                         if (retval < 0)
 352                                 goto err_out;
 353                         else {
 354                                 struct iattr iattr;
 355                                 if (retval == 0) {
 356                                         /*
 357                                          * ACL can be represented
 358                                          * by the mode bits. So don't
 359                                          * update ACL.
 360                                          */
 361                                         acl = NULL;
 362                                         value = NULL;
 363                                         size = 0;
 364                                 }
 365                                 /* Updte the mode bits */
 366                                 iattr.ia_mode = ((mode & S_IALLUGO) |
 367                                                  (inode->i_mode & ~S_IALLUGO));
 368                                 iattr.ia_valid = ATTR_MODE;
 369                                 /* FIXME should we update ctime ?
 370                                  * What is the following setxattr update the
 371                                  * mode ?
 372                                  */
 373                                 v9fs_vfs_setattr_dotl(dentry, &iattr);
 374                         }
 375                 }
 376                 break;
 377         case ACL_TYPE_DEFAULT:
 378                 name = POSIX_ACL_XATTR_DEFAULT;
 379                 if (!S_ISDIR(inode->i_mode)) {
 380                         retval = acl ? -EINVAL : 0;
 381                         goto err_out;
 382                 }
 383                 break;
 384         default:
 385                 BUG();
 386         }
 387         retval = v9fs_xattr_set(dentry, name, value, size, flags);
 388         if (!retval)
 389                 set_cached_acl(inode, type, acl);
 390 err_out:
 391         posix_acl_release(acl);
 392         return retval;
 393 }
 394
 395 const struct xattr_handler v9fs_xattr_acl_access_handler = {
 396         .prefix = POSIX_ACL_XATTR_ACCESS,
 397         .flags  = ACL_TYPE_ACCESS,
 398         .get    = v9fs_xattr_get_acl,
 399         .set    = v9fs_xattr_set_acl,
 400 };
 401
 402 const struct xattr_handler v9fs_xattr_acl_default_handler = {
 403         .prefix = POSIX_ACL_XATTR_DEFAULT,
 404         .flags  = ACL_TYPE_DEFAULT,
 405         .get    = v9fs_xattr_get_acl,
 406         .set    = v9fs_xattr_set_acl,
 407 };