fs/xfs/xfs_xattr.c

   1 /*
   2  * Copyright (C) 2008 Christoph Hellwig.
   3  * Portions Copyright (C) 2000-2008 Silicon Graphics, Inc.
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write the Free Software Foundation,
  16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17  */
  18
  19 #include "xfs.h"
  20 #include "xfs_format.h"
  21 #include "xfs_log_format.h"
  22 #include "xfs_trans_resv.h"
  23 #include "xfs_sb.h"
  24 #include "xfs_mount.h"
  25 #include "xfs_da_format.h"
  26 #include "xfs_inode.h"
  27 #include "xfs_attr.h"
  28 #include "xfs_attr_leaf.h"
  29 #include "xfs_acl.h"
  30
  31 #include <linux/posix_acl_xattr.h>
  32 #include <linux/xattr.h>
  33
  34
  35 static int
  36 xfs_xattr_get(struct dentry *dentry, const char *name,
  37                 void *value, size_t size, int xflags)
  38 {
  39         struct xfs_inode *ip = XFS_I(dentry->d_inode);
  40         int error, asize = size;
  41
  42         if (strcmp(name, "") == 0)
  43                 return -EINVAL;
  44
  45         /* Convert Linux syscall to XFS internal ATTR flags */
  46         if (!size) {
  47                 xflags |= ATTR_KERNOVAL;
  48                 value = NULL;
  49         }
  50
  51         error = xfs_attr_get(ip, (unsigned char *)name, value, &asize, xflags);
  52         if (error)
  53                 return error;
  54         return asize;
  55 }
  56
  57 static int
  58 xfs_xattr_set(struct dentry *dentry, const char *name, const void *value,
  59                 size_t size, int flags, int xflags)
  60 {
  61         struct xfs_inode *ip = XFS_I(dentry->d_inode);
  62
  63         if (strcmp(name, "") == 0)
  64                 return -EINVAL;
  65
  66         /* Convert Linux syscall to XFS internal ATTR flags */
  67         if (flags & XATTR_CREATE)
  68                 xflags |= ATTR_CREATE;
  69         if (flags & XATTR_REPLACE)
  70                 xflags |= ATTR_REPLACE;
  71
  72         if (!value)
  73                 return xfs_attr_remove(ip, (unsigned char *)name, xflags);
  74         return xfs_attr_set(ip, (unsigned char *)name,
  75                                 (void *)value, size, xflags);
  76 }
  77
  78 static const struct xattr_handler xfs_xattr_user_handler = {
  79         .prefix = XATTR_USER_PREFIX,
  80         .flags  = 0, /* no flags implies user namespace */
  81         .get    = xfs_xattr_get,
  82         .set    = xfs_xattr_set,
  83 };
  84
  85 static const struct xattr_handler xfs_xattr_trusted_handler = {
  86         .prefix = XATTR_TRUSTED_PREFIX,
  87         .flags  = ATTR_ROOT,
  88         .get    = xfs_xattr_get,
  89         .set    = xfs_xattr_set,
  90 };
  91
  92 static const struct xattr_handler xfs_xattr_security_handler = {
  93         .prefix = XATTR_SECURITY_PREFIX,
  94         .flags  = ATTR_SECURE,
  95         .get    = xfs_xattr_get,
  96         .set    = xfs_xattr_set,
  97 };
  98
  99 const struct xattr_handler *xfs_xattr_handlers[] = {
 100         &xfs_xattr_user_handler,
 101         &xfs_xattr_trusted_handler,
 102         &xfs_xattr_security_handler,
 103 #ifdef CONFIG_XFS_POSIX_ACL
 104         &posix_acl_access_xattr_handler,
 105         &posix_acl_default_xattr_handler,
 106 #endif
 107         NULL
 108 };
 109
 110 static unsigned int xfs_xattr_prefix_len(int flags)
 111 {
 112         if (flags & XFS_ATTR_SECURE)
 113                 return sizeof("security");
 114         else if (flags & XFS_ATTR_ROOT)
 115                 return sizeof("trusted");
 116         else
 117                 return sizeof("user");
 118 }
 119
 120 static const char *xfs_xattr_prefix(int flags)
 121 {
 122         if (flags & XFS_ATTR_SECURE)
 123                 return xfs_xattr_security_handler.prefix;
 124         else if (flags & XFS_ATTR_ROOT)
 125                 return xfs_xattr_trusted_handler.prefix;
 126         else
 127                 return xfs_xattr_user_handler.prefix;
 128 }
 129
 130 static int
 131 xfs_xattr_put_listent(
 132         struct xfs_attr_list_context *context,
 133         int             flags,
 134         unsigned char   *name,
 135         int             namelen,
 136         int             valuelen,
 137         unsigned char   *value)
 138 {
 139         unsigned int prefix_len = xfs_xattr_prefix_len(flags);
 140         char *offset;
 141         int arraytop;
 142
 143         ASSERT(context->count >= 0);
 144
 145         /*
 146          * Only show root namespace entries if we are actually allowed to
 147          * see them.
 148          */
 149         if ((flags & XFS_ATTR_ROOT) && !capable(CAP_SYS_ADMIN))
 150                 return 0;
 151
 152         arraytop = context->count + prefix_len + namelen + 1;
 153         if (arraytop > context->firstu) {
 154                 context->count = -1;    /* insufficient space */
 155                 return 1;
 156         }
 157         offset = (char *)context->alist + context->count;
 158         strncpy(offset, xfs_xattr_prefix(flags), prefix_len);
 159         offset += prefix_len;
 160         strncpy(offset, (char *)name, namelen);                 /* real name */
 161         offset += namelen;
 162         *offset = '\0';
 163         context->count += prefix_len + namelen + 1;
 164         return 0;
 165 }
 166
 167 static int
 168 xfs_xattr_put_listent_sizes(
 169         struct xfs_attr_list_context *context,
 170         int             flags,
 171         unsigned char   *name,
 172         int             namelen,
 173         int             valuelen,
 174         unsigned char   *value)
 175 {
 176         context->count += xfs_xattr_prefix_len(flags) + namelen + 1;
 177         return 0;
 178 }
 179
 180 static int
 181 list_one_attr(const char *name, const size_t len, void *data,
 182                 size_t size, ssize_t *result)
 183 {
 184         char *p = data + *result;
 185
 186         *result += len;
 187         if (!size)
 188                 return 0;
 189         if (*result > size)
 190                 return -ERANGE;
 191
 192         strcpy(p, name);
 193         return 0;
 194 }
 195
 196 ssize_t
 197 xfs_vn_listxattr(struct dentry *dentry, char *data, size_t size)
 198 {
 199         struct xfs_attr_list_context context;
 200         struct attrlist_cursor_kern cursor = { 0 };
 201         struct inode            *inode = dentry->d_inode;
 202         int                     error;
 203
 204         /*
 205          * First read the regular on-disk attributes.
 206          */
 207         memset(&context, 0, sizeof(context));
 208         context.dp = XFS_I(inode);
 209         context.cursor = &cursor;
 210         context.resynch = 1;
 211         context.alist = data;
 212         context.bufsize = size;
 213         context.firstu = context.bufsize;
 214
 215         if (size)
 216                 context.put_listent = xfs_xattr_put_listent;
 217         else
 218                 context.put_listent = xfs_xattr_put_listent_sizes;
 219
 220         xfs_attr_list_int(&context);
 221         if (context.count < 0)
 222                 return -ERANGE;
 223
 224         /*
 225          * Then add the two synthetic ACL attributes.
 226          */
 227         if (posix_acl_access_exists(inode)) {
 228                 error = list_one_attr(POSIX_ACL_XATTR_ACCESS,
 229                                 strlen(POSIX_ACL_XATTR_ACCESS) + 1,
 230                                 data, size, &context.count);
 231                 if (error)
 232                         return error;
 233         }
 234
 235         if (posix_acl_default_exists(inode)) {
 236                 error = list_one_attr(POSIX_ACL_XATTR_DEFAULT,
 237                                 strlen(POSIX_ACL_XATTR_DEFAULT) + 1,
 238                                 data, size, &context.count);
 239                 if (error)
 240                         return error;
 241         }
 242
 243         return context.count;
 244 }