release/src-rt-6.x.4708/linux/linux-2.6.36/fs/squashfs/xattr.c

   1 /* Modified by Broadcom Corp. Portions Copyright (c) Broadcom Corp, 2012. */
   2 /*
   3  * Squashfs - a compressed read only filesystem for Linux
   4  *
   5  * Copyright (c) 2010
   6  * Phillip Lougher <phillip@lougher.demon.co.uk>
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License
  10  * as published by the Free Software Foundation; either version 2,
  11  * or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  *
  22  * xattr.c
  23  */
  24
  25 #include <linux/init.h>
  26 #include <linux/module.h>
  27 #include <linux/string.h>
  28 #include <linux/fs.h>
  29 #include <linux/vfs.h>
  30 #include <linux/xattr.h>
  31 #include <linux/slab.h>
  32
  33 #include "squashfs_fs.h"
  34 #include "squashfs_fs_sb.h"
  35 #include "squashfs_fs_i.h"
  36 #include "squashfs.h"
  37
  38 static const struct xattr_handler *squashfs_xattr_handler(int);
  39
  40 ssize_t squashfs_listxattr(struct dentry *d, char *buffer,
  41         size_t buffer_size)
  42 {
  43         struct inode *inode = d->d_inode;
  44         struct super_block *sb = inode->i_sb;
  45         struct squashfs_sb_info *msblk = sb->s_fs_info;
  46         u64 start = SQUASHFS_XATTR_BLK(squashfs_i(inode)->xattr)
  47                                                  + msblk->xattr_table;
  48         int offset = SQUASHFS_XATTR_OFFSET(squashfs_i(inode)->xattr);
  49         int count = squashfs_i(inode)->xattr_count;
  50         size_t rest = buffer_size;
  51         int err;
  52
  53         /* check that the file system has xattrs */
  54         if (msblk->xattr_id_table == NULL)
  55                 return -EOPNOTSUPP;
  56
  57         /* loop reading each xattr name */
  58         while (count--) {
  59                 struct squashfs_xattr_entry entry;
  60                 struct squashfs_xattr_val val;
  61                 const struct xattr_handler *handler;
  62                 int name_size, prefix_size = 0;
  63
  64                 err = squashfs_read_metadata(sb, &entry, &start, &offset,
  65                                                         sizeof(entry));
  66                 if (err < 0)
  67                         goto failed;
  68
  69                 name_size = le16_to_cpu(entry.size);
  70                 handler = squashfs_xattr_handler(le16_to_cpu(entry.type));
  71                 if (handler)
  72                         prefix_size = handler->list(d, buffer, rest, NULL,
  73                                 name_size, handler->flags);
  74                 if (prefix_size) {
  75                         if (buffer) {
  76                                 if (prefix_size + name_size + 1 > rest) {
  77                                         err = -ERANGE;
  78                                         goto failed;
  79                                 }
  80                                 buffer += prefix_size;
  81                         }
  82                         err = squashfs_read_metadata(sb, buffer, &start,
  83                                 &offset, name_size);
  84                         if (err < 0)
  85                                 goto failed;
  86                         if (buffer) {
  87                                 buffer[name_size] = '\0';
  88                                 buffer += name_size + 1;
  89                         }
  90                         rest -= prefix_size + name_size + 1;
  91                 } else  {
  92                         /* no handler or insuffficient privileges, so skip */
  93                         err = squashfs_read_metadata(sb, NULL, &start,
  94                                 &offset, name_size);
  95                         if (err < 0)
  96                                 goto failed;
  97                 }
  98
  99
 100                 /* skip remaining xattr entry */
 101                 err = squashfs_read_metadata(sb, &val, &start, &offset,
 102                                                 sizeof(val));
 103                 if (err < 0)
 104                         goto failed;
 105
 106                 err = squashfs_read_metadata(sb, NULL, &start, &offset,
 107                                                 le32_to_cpu(val.vsize));
 108                 if (err < 0)
 109                         goto failed;
 110         }
 111         err = buffer_size - rest;
 112
 113 failed:
 114         return err;
 115 }
 116
 117
 118 static int squashfs_xattr_get(struct inode *inode, int name_index,
 119         const char *name, void *buffer, size_t buffer_size)
 120 {
 121         struct super_block *sb = inode->i_sb;
 122         struct squashfs_sb_info *msblk = sb->s_fs_info;
 123         u64 start = SQUASHFS_XATTR_BLK(squashfs_i(inode)->xattr)
 124                                                  + msblk->xattr_table;
 125         int offset = SQUASHFS_XATTR_OFFSET(squashfs_i(inode)->xattr);
 126         int count = squashfs_i(inode)->xattr_count;
 127         int name_len = strlen(name);
 128         int err, vsize;
 129         char *target = kmalloc(name_len, GFP_KERNEL);
 130
 131         if (target == NULL)
 132                 return  -ENOMEM;
 133
 134         /* loop reading each xattr name */
 135         for (; count; count--) {
 136                 struct squashfs_xattr_entry entry;
 137                 struct squashfs_xattr_val val;
 138                 int type, prefix, name_size;
 139
 140                 err = squashfs_read_metadata(sb, &entry, &start, &offset,
 141                                                         sizeof(entry));
 142                 if (err < 0)
 143                         goto failed;
 144
 145                 name_size = le16_to_cpu(entry.size);
 146                 type = le16_to_cpu(entry.type);
 147                 prefix = type & SQUASHFS_XATTR_PREFIX_MASK;
 148
 149                 if (prefix == name_index && name_size == name_len)
 150                         err = squashfs_read_metadata(sb, target, &start,
 151                                                 &offset, name_size);
 152                 else
 153                         err = squashfs_read_metadata(sb, NULL, &start,
 154                                                 &offset, name_size);
 155                 if (err < 0)
 156                         goto failed;
 157
 158                 if (prefix == name_index && name_size == name_len &&
 159                                         strncmp(target, name, name_size) == 0) {
 160                         /* found xattr */
 161                         if (type & SQUASHFS_XATTR_VALUE_OOL) {
 162                                 __le64 xattr_val;
 163                                 u64 xattr;
 164                                 /* val is a reference to the real location */
 165                                 err = squashfs_read_metadata(sb, &val, &start,
 166                                                 &offset, sizeof(val));
 167                                 if (err < 0)
 168                                         goto failed;
 169                                 err = squashfs_read_metadata(sb, &xattr_val,
 170                                         &start, &offset, sizeof(xattr_val));
 171                                 if (err < 0)
 172                                         goto failed;
 173                                 xattr = le64_to_cpu(xattr_val);
 174                                 start = SQUASHFS_XATTR_BLK(xattr) +
 175                                                         msblk->xattr_table;
 176                                 offset = SQUASHFS_XATTR_OFFSET(xattr);
 177                         }
 178                         /* read xattr value */
 179                         err = squashfs_read_metadata(sb, &val, &start, &offset,
 180                                                         sizeof(val));
 181                         if (err < 0)
 182                                 goto failed;
 183
 184                         vsize = le32_to_cpu(val.vsize);
 185                         if (buffer) {
 186                                 if (vsize > buffer_size) {
 187                                         err = -ERANGE;
 188                                         goto failed;
 189                                 }
 190                                 err = squashfs_read_metadata(sb, buffer, &start,
 191                                          &offset, vsize);
 192                                 if (err < 0)
 193                                         goto failed;
 194                         }
 195                         break;
 196                 }
 197
 198                 /* no match, skip remaining xattr entry */
 199                 err = squashfs_read_metadata(sb, &val, &start, &offset,
 200                                                         sizeof(val));
 201                 if (err < 0)
 202                         goto failed;
 203                 err = squashfs_read_metadata(sb, NULL, &start, &offset,
 204                                                 le32_to_cpu(val.vsize));
 205                 if (err < 0)
 206                         goto failed;
 207         }
 208         err = count ? vsize : -ENODATA;
 209
 210 failed:
 211         kfree(target);
 212         return err;
 213 }
 214
 215
 216 /*
 217  * User namespace support
 218  */
 219 static size_t squashfs_user_list(struct dentry *d, char *list, size_t list_size,
 220         const char *name, size_t name_len, int type)
 221 {
 222         if (list && XATTR_USER_PREFIX_LEN <= list_size)
 223                 memcpy(list, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN);
 224         return XATTR_USER_PREFIX_LEN;
 225 }
 226
 227 static int squashfs_user_get(struct dentry *d, const char *name, void *buffer,
 228         size_t size, int type)
 229 {
 230         if (name[0] == '\0')
 231                 return  -EINVAL;
 232
 233         return squashfs_xattr_get(d->d_inode, SQUASHFS_XATTR_USER, name,
 234                 buffer, size);
 235 }
 236
 237 static const struct xattr_handler squashfs_xattr_user_handler = {
 238         .prefix = XATTR_USER_PREFIX,
 239         .list   = squashfs_user_list,
 240         .get    = squashfs_user_get
 241 };
 242
 243 /*
 244  * Trusted namespace support
 245  */
 246 static size_t squashfs_trusted_list(struct dentry *d, char *list,
 247         size_t list_size, const char *name, size_t name_len, int type)
 248 {
 249         if (!capable(CAP_SYS_ADMIN))
 250                 return 0;
 251
 252         if (list && XATTR_TRUSTED_PREFIX_LEN <= list_size)
 253                 memcpy(list, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
 254         return XATTR_TRUSTED_PREFIX_LEN;
 255 }
 256
 257 static int squashfs_trusted_get(struct dentry *d, const char *name,
 258         void *buffer, size_t size, int type)
 259 {
 260         if (name[0] == '\0')
 261                 return  -EINVAL;
 262
 263         return squashfs_xattr_get(d->d_inode, SQUASHFS_XATTR_TRUSTED, name,
 264                 buffer, size);
 265 }
 266
 267 static const struct xattr_handler squashfs_xattr_trusted_handler = {
 268         .prefix = XATTR_TRUSTED_PREFIX,
 269         .list   = squashfs_trusted_list,
 270         .get    = squashfs_trusted_get
 271 };
 272
 273 /*
 274  * Security namespace support
 275  */
 276 static size_t squashfs_security_list(struct dentry *d, char *list,
 277         size_t list_size, const char *name, size_t name_len, int type)
 278 {
 279         if (list && XATTR_SECURITY_PREFIX_LEN <= list_size)
 280                 memcpy(list, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN);
 281         return XATTR_SECURITY_PREFIX_LEN;
 282 }
 283
 284 static int squashfs_security_get(struct dentry *d, const char *name,
 285         void *buffer, size_t size, int type)
 286 {
 287         if (name[0] == '\0')
 288                 return  -EINVAL;
 289
 290         return squashfs_xattr_get(d->d_inode, SQUASHFS_XATTR_SECURITY, name,
 291                 buffer, size);
 292 }
 293
 294 static const struct xattr_handler squashfs_xattr_security_handler = {
 295         .prefix = XATTR_SECURITY_PREFIX,
 296         .list   = squashfs_security_list,
 297         .get    = squashfs_security_get
 298 };
 299
 300 static const struct xattr_handler *squashfs_xattr_handler(int type)
 301 {
 302         if (type & ~(SQUASHFS_XATTR_PREFIX_MASK | SQUASHFS_XATTR_VALUE_OOL))
 303                 /* ignore unrecognised type */
 304                 return NULL;
 305
 306         switch (type & SQUASHFS_XATTR_PREFIX_MASK) {
 307         case SQUASHFS_XATTR_USER:
 308                 return &squashfs_xattr_user_handler;
 309         case SQUASHFS_XATTR_TRUSTED:
 310                 return &squashfs_xattr_trusted_handler;
 311         case SQUASHFS_XATTR_SECURITY:
 312                 return &squashfs_xattr_security_handler;
 313         default:
 314                 /* ignore unrecognised type */
 315                 return NULL;
 316         }
 317 }
 318
 319 const struct xattr_handler *squashfs_xattr_handlers[] = {
 320         &squashfs_xattr_user_handler,
 321         &squashfs_xattr_trusted_handler,
 322         &squashfs_xattr_security_handler,
 323         NULL
 324 };