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