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 #include "fid.h"
  27
  28 static struct posix_acl *__v9fs_get_acl(struct p9_fid *fid, char *name)
  29 {
  30         ssize_t size;
  31         void *value = NULL;
  32         struct posix_acl *acl = NULL;
  33
  34         size = v9fs_fid_xattr_get(fid, name, NULL, 0);
  35         if (size > 0) {
  36                 value = kzalloc(size, GFP_NOFS);
  37                 if (!value)
  38                         return ERR_PTR(-ENOMEM);
  39                 size = v9fs_fid_xattr_get(fid, name, value, size);
  40                 if (size > 0) {
  41                         acl = posix_acl_from_xattr(&init_user_ns, value, size);
  42                         if (IS_ERR(acl))
  43                                 goto err_out;
  44                 }
  45         } else if (size == -ENODATA || size == 0 ||
  46                    size == -ENOSYS || size == -EOPNOTSUPP) {
  47                 acl = NULL;
  48         } else
  49                 acl = ERR_PTR(-EIO);
  50
  51 err_out:
  52         kfree(value);
  53         return acl;
  54 }
  55
  56 int v9fs_get_acl(struct inode *inode, struct p9_fid *fid)
  57 {
  58         int retval = 0;
  59         struct posix_acl *pacl, *dacl;
  60         struct v9fs_session_info *v9ses;
  61
  62         v9ses = v9fs_inode2v9ses(inode);
  63         if (((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT) ||
  64                         ((v9ses->flags & V9FS_ACL_MASK) != V9FS_POSIX_ACL)) {
  65                 set_cached_acl(inode, ACL_TYPE_DEFAULT, NULL);
  66                 set_cached_acl(inode, ACL_TYPE_ACCESS, NULL);
  67                 return 0;
  68         }
  69         /* get the default/access acl values and cache them */
  70         dacl = __v9fs_get_acl(fid, XATTR_NAME_POSIX_ACL_DEFAULT);
  71         pacl = __v9fs_get_acl(fid, XATTR_NAME_POSIX_ACL_ACCESS);
  72
  73         if (!IS_ERR(dacl) && !IS_ERR(pacl)) {
  74                 set_cached_acl(inode, ACL_TYPE_DEFAULT, dacl);
  75                 set_cached_acl(inode, ACL_TYPE_ACCESS, pacl);
  76         } else
  77                 retval = -EIO;
  78
  79         if (!IS_ERR(dacl))
  80                 posix_acl_release(dacl);
  81
  82         if (!IS_ERR(pacl))
  83                 posix_acl_release(pacl);
  84
  85         return retval;
  86 }
  87
  88 static struct posix_acl *v9fs_get_cached_acl(struct inode *inode, int type)
  89 {
  90         struct posix_acl *acl;
  91         /*
  92          * 9p Always cache the acl value when
  93          * instantiating the inode (v9fs_inode_from_fid)
  94          */
  95         acl = get_cached_acl(inode, type);
  96         BUG_ON(is_uncached_acl(acl));
  97         return acl;
  98 }
  99
 100 struct posix_acl *v9fs_iop_get_acl(struct inode *inode, int type)
 101 {
 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 NULL;
 112         }
 113         return v9fs_get_cached_acl(inode, type);
 114
 115 }
 116
 117 static int v9fs_set_acl(struct p9_fid *fid, int type, struct posix_acl *acl)
 118 {
 119         int retval;
 120         char *name;
 121         size_t size;
 122         void *buffer;
 123         if (!acl)
 124                 return 0;
 125
 126         /* Set a setxattr request to server */
 127         size = posix_acl_xattr_size(acl->a_count);
 128         buffer = kmalloc(size, GFP_KERNEL);
 129         if (!buffer)
 130                 return -ENOMEM;
 131         retval = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
 132         if (retval < 0)
 133                 goto err_free_out;
 134         switch (type) {
 135         case ACL_TYPE_ACCESS:
 136                 name = XATTR_NAME_POSIX_ACL_ACCESS;
 137                 break;
 138         case ACL_TYPE_DEFAULT:
 139                 name = XATTR_NAME_POSIX_ACL_DEFAULT;
 140                 break;
 141         default:
 142                 BUG();
 143         }
 144         retval = v9fs_fid_xattr_set(fid, name, buffer, size, 0);
 145 err_free_out:
 146         kfree(buffer);
 147         return retval;
 148 }
 149
 150 int v9fs_acl_chmod(struct inode *inode, struct p9_fid *fid)
 151 {
 152         int retval = 0;
 153         struct posix_acl *acl;
 154
 155         if (S_ISLNK(inode->i_mode))
 156                 return -EOPNOTSUPP;
 157         acl = v9fs_get_cached_acl(inode, ACL_TYPE_ACCESS);
 158         if (acl) {
 159                 retval = __posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
 160                 if (retval)
 161                         return retval;
 162                 set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
 163                 retval = v9fs_set_acl(fid, ACL_TYPE_ACCESS, acl);
 164                 posix_acl_release(acl);
 165         }
 166         return retval;
 167 }
 168
 169 int v9fs_set_create_acl(struct inode *inode, struct p9_fid *fid,
 170                         struct posix_acl *dacl, struct posix_acl *acl)
 171 {
 172         set_cached_acl(inode, ACL_TYPE_DEFAULT, dacl);
 173         set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
 174         v9fs_set_acl(fid, ACL_TYPE_DEFAULT, dacl);
 175         v9fs_set_acl(fid, ACL_TYPE_ACCESS, acl);
 176         return 0;
 177 }
 178
 179 void v9fs_put_acl(struct posix_acl *dacl,
 180                   struct posix_acl *acl)
 181 {
 182         posix_acl_release(dacl);
 183         posix_acl_release(acl);
 184 }
 185
 186 int v9fs_acl_mode(struct inode *dir, umode_t *modep,
 187                   struct posix_acl **dpacl, struct posix_acl **pacl)
 188 {
 189         int retval = 0;
 190         umode_t mode = *modep;
 191         struct posix_acl *acl = NULL;
 192
 193         if (!S_ISLNK(mode)) {
 194                 acl = v9fs_get_cached_acl(dir, ACL_TYPE_DEFAULT);
 195                 if (IS_ERR(acl))
 196                         return PTR_ERR(acl);
 197                 if (!acl)
 198                         mode &= ~current_umask();
 199         }
 200         if (acl) {
 201                 if (S_ISDIR(mode))
 202                         *dpacl = posix_acl_dup(acl);
 203                 retval = __posix_acl_create(&acl, GFP_NOFS, &mode);
 204                 if (retval < 0)
 205                         return retval;
 206                 if (retval > 0)
 207                         *pacl = acl;
 208                 else
 209                         posix_acl_release(acl);
 210         }
 211         *modep  = mode;
 212         return 0;
 213 }
 214
 215 static int v9fs_xattr_get_acl(const struct xattr_handler *handler,
 216                               struct dentry *dentry, struct inode *inode,
 217                               const char *name, void *buffer, size_t size)
 218 {
 219         struct v9fs_session_info *v9ses;
 220         struct posix_acl *acl;
 221         int error;
 222
 223         v9ses = v9fs_dentry2v9ses(dentry);
 224         /*
 225          * We allow set/get/list of acl when access=client is not specified
 226          */
 227         if ((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT)
 228                 return v9fs_xattr_get(dentry, handler->name, buffer, size);
 229
 230         acl = v9fs_get_cached_acl(inode, handler->flags);
 231         if (IS_ERR(acl))
 232                 return PTR_ERR(acl);
 233         if (acl == NULL)
 234                 return -ENODATA;
 235         error = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
 236         posix_acl_release(acl);
 237
 238         return error;
 239 }
 240
 241 static int v9fs_xattr_set_acl(const struct xattr_handler *handler,
 242                               struct dentry *dentry, struct inode *inode,
 243                               const char *name, const void *value,
 244                               size_t size, int flags)
 245 {
 246         int retval;
 247         struct posix_acl *acl;
 248         struct v9fs_session_info *v9ses;
 249
 250         v9ses = v9fs_dentry2v9ses(dentry);
 251         /*
 252          * set the attribute on the remote. Without even looking at the
 253          * xattr value. We leave it to the server to validate
 254          */
 255         if ((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT)
 256                 return v9fs_xattr_set(dentry, handler->name, value, size,
 257                                       flags);
 258
 259         if (S_ISLNK(inode->i_mode))
 260                 return -EOPNOTSUPP;
 261         if (!inode_owner_or_capable(inode))
 262                 return -EPERM;
 263         if (value) {
 264                 /* update the cached acl value */
 265                 acl = posix_acl_from_xattr(&init_user_ns, value, size);
 266                 if (IS_ERR(acl))
 267                         return PTR_ERR(acl);
 268                 else if (acl) {
 269                         retval = posix_acl_valid(inode->i_sb->s_user_ns, acl);
 270                         if (retval)
 271                                 goto err_out;
 272                 }
 273         } else
 274                 acl = NULL;
 275
 276         switch (handler->flags) {
 277         case ACL_TYPE_ACCESS:
 278                 if (acl) {
 279                         struct iattr iattr;
 280                         struct posix_acl *old_acl = acl;
 281
 282                         retval = posix_acl_update_mode(inode, &iattr.ia_mode, &acl);
 283                         if (retval)
 284                                 goto err_out;
 285                         if (!acl) {
 286                                 /*
 287                                  * ACL can be represented
 288                                  * by the mode bits. So don't
 289                                  * update ACL.
 290                                  */
 291                                 posix_acl_release(old_acl);
 292                                 value = NULL;
 293                                 size = 0;
 294                         }
 295                         iattr.ia_valid = ATTR_MODE;
 296                         /* FIXME should we update ctime ?
 297                          * What is the following setxattr update the
 298                          * mode ?
 299                          */
 300                         v9fs_vfs_setattr_dotl(dentry, &iattr);
 301                 }
 302                 break;
 303         case ACL_TYPE_DEFAULT:
 304                 if (!S_ISDIR(inode->i_mode)) {
 305                         retval = acl ? -EINVAL : 0;
 306                         goto err_out;
 307                 }
 308                 break;
 309         default:
 310                 BUG();
 311         }
 312         retval = v9fs_xattr_set(dentry, handler->name, value, size, flags);
 313         if (!retval)
 314                 set_cached_acl(inode, handler->flags, acl);
 315 err_out:
 316         posix_acl_release(acl);
 317         return retval;
 318 }
 319
 320 const struct xattr_handler v9fs_xattr_acl_access_handler = {
 321         .name   = XATTR_NAME_POSIX_ACL_ACCESS,
 322         .flags  = ACL_TYPE_ACCESS,
 323         .get    = v9fs_xattr_get_acl,
 324         .set    = v9fs_xattr_set_acl,
 325 };
 326
 327 const struct xattr_handler v9fs_xattr_acl_default_handler = {
 328         .name   = XATTR_NAME_POSIX_ACL_DEFAULT,
 329         .flags  = ACL_TYPE_DEFAULT,
 330         .get    = v9fs_xattr_get_acl,
 331         .set    = v9fs_xattr_set_acl,
 332 };