fs/squashfs/xattr.c

   1 /*
   2  * Squashfs - a compressed read only filesystem for Linux
   3  *
   4  * Copyright (c) 2010
   5  * Phillip Lougher <phillip@squashfs.org.uk>
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * as published by the Free Software Foundation; either version 2,
  10  * or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  20  *
  21  * xattr.c
  22  */
  23
  24 #include <linux/init.h>
  25 #include <linux/module.h>
  26 #include <linux/string.h>
  27 #include <linux/fs.h>
  28 #include <linux/vfs.h>
  29 #include <linux/xattr.h>
  30 #include <linux/slab.h>
  31
  32 #include "squashfs_fs.h"
  33 #include "squashfs_fs_sb.h"
  34 #include "squashfs_fs_i.h"
  35 #include "squashfs.h"
  36
  37 static const struct xattr_handler *squashfs_xattr_handler(int);
  38
  39 ssize_t squashfs_listxattr(struct dentry *d, char *buffer,
  40         size_t buffer_size)
  41 {
  42         struct inode *inode = d_inode(d);
  43         struct super_block *sb = inode->i_sb;
  44         struct squashfs_sb_info *msblk = sb->s_fs_info;
  45         u64 start = SQUASHFS_XATTR_BLK(squashfs_i(inode)->xattr)
  46                                                  + msblk->xattr_table;
  47         int offset = SQUASHFS_XATTR_OFFSET(squashfs_i(inode)->xattr);
  48         int count = squashfs_i(inode)->xattr_count;
  49         size_t rest = buffer_size;
  50         int err;
  51
  52         /* check that the file system has xattrs */
  53         if (msblk->xattr_id_table == NULL)
  54                 return -EOPNOTSUPP;
  55
  56         /* loop reading each xattr name */
  57         while (count--) {
  58                 struct squashfs_xattr_entry entry;
  59                 struct squashfs_xattr_val val;
  60                 const struct xattr_handler *handler;
  61                 int name_size;
  62
  63                 err = squashfs_read_metadata(sb, &entry, &start, &offset,
  64                                                         sizeof(entry));
  65                 if (err < 0)
  66                         goto failed;
  67
  68                 name_size = le16_to_cpu(entry.size);
  69                 handler = squashfs_xattr_handler(le16_to_cpu(entry.type));
  70                 if (handler && (!handler->list || handler->list(d))) {
  71                         const char *prefix = handler->prefix ?: handler->name;
  72                         size_t prefix_size = strlen(prefix);
  73
  74                         if (buffer) {
  75                                 if (prefix_size + name_size + 1 > rest) {
  76                                         err = -ERANGE;
  77                                         goto failed;
  78                                 }
  79                                 memcpy(buffer, prefix, prefix_size);
  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 static int squashfs_xattr_handler_get(const struct xattr_handler *handler,
 217                                       struct dentry *d, const char *name,
 218                                       void *buffer, size_t size)
 219 {
 220         return squashfs_xattr_get(d_inode(d), handler->flags, name,
 221                 buffer, size);
 222 }
 223
 224 /*
 225  * User namespace support
 226  */
 227 static const struct xattr_handler squashfs_xattr_user_handler = {
 228         .prefix = XATTR_USER_PREFIX,
 229         .flags  = SQUASHFS_XATTR_USER,
 230         .get    = squashfs_xattr_handler_get
 231 };
 232
 233 /*
 234  * Trusted namespace support
 235  */
 236 static bool squashfs_trusted_xattr_handler_list(struct dentry *d)
 237 {
 238         return capable(CAP_SYS_ADMIN);
 239 }
 240
 241 static const struct xattr_handler squashfs_xattr_trusted_handler = {
 242         .prefix = XATTR_TRUSTED_PREFIX,
 243         .flags  = SQUASHFS_XATTR_TRUSTED,
 244         .list   = squashfs_trusted_xattr_handler_list,
 245         .get    = squashfs_xattr_handler_get
 246 };
 247
 248 /*
 249  * Security namespace support
 250  */
 251 static const struct xattr_handler squashfs_xattr_security_handler = {
 252         .prefix = XATTR_SECURITY_PREFIX,
 253         .flags  = SQUASHFS_XATTR_SECURITY,
 254         .get    = squashfs_xattr_handler_get
 255 };
 256
 257 static const struct xattr_handler *squashfs_xattr_handler(int type)
 258 {
 259         if (type & ~(SQUASHFS_XATTR_PREFIX_MASK | SQUASHFS_XATTR_VALUE_OOL))
 260                 /* ignore unrecognised type */
 261                 return NULL;
 262
 263         switch (type & SQUASHFS_XATTR_PREFIX_MASK) {
 264         case SQUASHFS_XATTR_USER:
 265                 return &squashfs_xattr_user_handler;
 266         case SQUASHFS_XATTR_TRUSTED:
 267                 return &squashfs_xattr_trusted_handler;
 268         case SQUASHFS_XATTR_SECURITY:
 269                 return &squashfs_xattr_security_handler;
 270         default:
 271                 /* ignore unrecognised type */
 272                 return NULL;
 273         }
 274 }
 275
 276 const struct xattr_handler *squashfs_xattr_handlers[] = {
 277         &squashfs_xattr_user_handler,
 278         &squashfs_xattr_trusted_handler,
 279         &squashfs_xattr_security_handler,
 280         NULL
 281 };
 282