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_log_format.h"
  21 #include "xfs_da_btree.h"
  22 #include "xfs_bmap_btree.h"
  23 #include "xfs_inode.h"
  24 #include "xfs_attr.h"
  25 #include "xfs_attr_leaf.h"
  26 #include "xfs_acl.h"
  27
  28 #include <linux/posix_acl_xattr.h>
  29 #include <linux/xattr.h>
  30
  31
  32 static int
  33 xfs_xattr_get(struct dentry *dentry, const char *name,
  34                 void *value, size_t size, int xflags)
  35 {
  36         struct xfs_inode *ip = XFS_I(dentry->d_inode);
  37         int error, asize = size;
  38
  39         if (strcmp(name, "") == 0)
  40                 return -EINVAL;
  41
  42         /* Convert Linux syscall to XFS internal ATTR flags */
  43         if (!size) {
  44                 xflags |= ATTR_KERNOVAL;
  45                 value = NULL;
  46         }
  47
  48         error = -xfs_attr_get(ip, (unsigned char *)name, value, &asize, xflags);
  49         if (error)
  50                 return error;
  51         return asize;
  52 }
  53
  54 static int
  55 xfs_xattr_set(struct dentry *dentry, const char *name, const void *value,
  56                 size_t size, int flags, int xflags)
  57 {
  58         struct xfs_inode *ip = XFS_I(dentry->d_inode);
  59
  60         if (strcmp(name, "") == 0)
  61                 return -EINVAL;
  62
  63         /* Convert Linux syscall to XFS internal ATTR flags */
  64         if (flags & XATTR_CREATE)
  65                 xflags |= ATTR_CREATE;
  66         if (flags & XATTR_REPLACE)
  67                 xflags |= ATTR_REPLACE;
  68
  69         if (!value)
  70                 return -xfs_attr_remove(ip, (unsigned char *)name, xflags);
  71         return -xfs_attr_set(ip, (unsigned char *)name,
  72                                 (void *)value, size, xflags);
  73 }
  74
  75 static const struct xattr_handler xfs_xattr_user_handler = {
  76         .prefix = XATTR_USER_PREFIX,
  77         .flags  = 0, /* no flags implies user namespace */
  78         .get    = xfs_xattr_get,
  79         .set    = xfs_xattr_set,
  80 };
  81
  82 static const struct xattr_handler xfs_xattr_trusted_handler = {
  83         .prefix = XATTR_TRUSTED_PREFIX,
  84         .flags  = ATTR_ROOT,
  85         .get    = xfs_xattr_get,
  86         .set    = xfs_xattr_set,
  87 };
  88
  89 static const struct xattr_handler xfs_xattr_security_handler = {
  90         .prefix = XATTR_SECURITY_PREFIX,
  91         .flags  = ATTR_SECURE,
  92         .get    = xfs_xattr_get,
  93         .set    = xfs_xattr_set,
  94 };
  95
  96 const struct xattr_handler *xfs_xattr_handlers[] = {
  97         &xfs_xattr_user_handler,
  98         &xfs_xattr_trusted_handler,
  99         &xfs_xattr_security_handler,
 100 #ifdef CONFIG_XFS_POSIX_ACL
 101         &xfs_xattr_acl_access_handler,
 102         &xfs_xattr_acl_default_handler,
 103 #endif
 104         NULL
 105 };
 106
 107 static unsigned int xfs_xattr_prefix_len(int flags)
 108 {
 109         if (flags & XFS_ATTR_SECURE)
 110                 return sizeof("security");
 111         else if (flags & XFS_ATTR_ROOT)
 112                 return sizeof("trusted");
 113         else
 114                 return sizeof("user");
 115 }
 116
 117 static const char *xfs_xattr_prefix(int flags)
 118 {
 119         if (flags & XFS_ATTR_SECURE)
 120                 return xfs_xattr_security_handler.prefix;
 121         else if (flags & XFS_ATTR_ROOT)
 122                 return xfs_xattr_trusted_handler.prefix;
 123         else
 124                 return xfs_xattr_user_handler.prefix;
 125 }
 126
 127 static int
 128 xfs_xattr_put_listent(
 129         struct xfs_attr_list_context *context,
 130         int             flags,
 131         unsigned char   *name,
 132         int             namelen,
 133         int             valuelen,
 134         unsigned char   *value)
 135 {
 136         unsigned int prefix_len = xfs_xattr_prefix_len(flags);
 137         char *offset;
 138         int arraytop;
 139
 140         ASSERT(context->count >= 0);
 141
 142         /*
 143          * Only show root namespace entries if we are actually allowed to
 144          * see them.
 145          */
 146         if ((flags & XFS_ATTR_ROOT) && !capable(CAP_SYS_ADMIN))
 147                 return 0;
 148
 149         arraytop = context->count + prefix_len + namelen + 1;
 150         if (arraytop > context->firstu) {
 151                 context->count = -1;    /* insufficient space */
 152                 return 1;
 153         }
 154         offset = (char *)context->alist + context->count;
 155         strncpy(offset, xfs_xattr_prefix(flags), prefix_len);
 156         offset += prefix_len;
 157         strncpy(offset, (char *)name, namelen);                 /* real name */
 158         offset += namelen;
 159         *offset = '\0';
 160         context->count += prefix_len + namelen + 1;
 161         return 0;
 162 }
 163
 164 static int
 165 xfs_xattr_put_listent_sizes(
 166         struct xfs_attr_list_context *context,
 167         int             flags,
 168         unsigned char   *name,
 169         int             namelen,
 170         int             valuelen,
 171         unsigned char   *value)
 172 {
 173         context->count += xfs_xattr_prefix_len(flags) + namelen + 1;
 174         return 0;
 175 }
 176
 177 static int
 178 list_one_attr(const char *name, const size_t len, void *data,
 179                 size_t size, ssize_t *result)
 180 {
 181         char *p = data + *result;
 182
 183         *result += len;
 184         if (!size)
 185                 return 0;
 186         if (*result > size)
 187                 return -ERANGE;
 188
 189         strcpy(p, name);
 190         return 0;
 191 }
 192
 193 ssize_t
 194 xfs_vn_listxattr(struct dentry *dentry, char *data, size_t size)
 195 {
 196         struct xfs_attr_list_context context;
 197         struct attrlist_cursor_kern cursor = { 0 };
 198         struct inode            *inode = dentry->d_inode;
 199         int                     error;
 200
 201         /*
 202          * First read the regular on-disk attributes.
 203          */
 204         memset(&context, 0, sizeof(context));
 205         context.dp = XFS_I(inode);
 206         context.cursor = &cursor;
 207         context.resynch = 1;
 208         context.alist = data;
 209         context.bufsize = size;
 210         context.firstu = context.bufsize;
 211
 212         if (size)
 213                 context.put_listent = xfs_xattr_put_listent;
 214         else
 215                 context.put_listent = xfs_xattr_put_listent_sizes;
 216
 217         xfs_attr_list_int(&context);
 218         if (context.count < 0)
 219                 return -ERANGE;
 220
 221         /*
 222          * Then add the two synthetic ACL attributes.
 223          */
 224         if (posix_acl_access_exists(inode)) {
 225                 error = list_one_attr(POSIX_ACL_XATTR_ACCESS,
 226                                 strlen(POSIX_ACL_XATTR_ACCESS) + 1,
 227                                 data, size, &context.count);
 228                 if (error)
 229                         return error;
 230         }
 231
 232         if (posix_acl_default_exists(inode)) {
 233                 error = list_one_attr(POSIX_ACL_XATTR_DEFAULT,
 234                                 strlen(POSIX_ACL_XATTR_DEFAULT) + 1,
 235                                 data, size, &context.count);
 236                 if (error)
 237                         return error;
 238         }
 239
 240         return context.count;
 241 }