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_mount.h"
  24 #include "xfs_da_format.h"
  25 #include "xfs_inode.h"
  26 #include "xfs_attr.h"
  27 #include "xfs_attr_leaf.h"
  28 #include "xfs_acl.h"
  29
  30 #include <linux/posix_acl_xattr.h>
  31 #include <linux/xattr.h>
  32
  33
  34 static int
  35 xfs_xattr_get(struct dentry *dentry, const char *name,
  36                 void *value, size_t size, int xflags)
  37 {
  38         struct xfs_inode *ip = XFS_I(d_inode(dentry));
  39         int error, asize = size;
  40
  41         if (strcmp(name, "") == 0)
  42                 return -EINVAL;
  43
  44         /* Convert Linux syscall to XFS internal ATTR flags */
  45         if (!size) {
  46                 xflags |= ATTR_KERNOVAL;
  47                 value = NULL;
  48         }
  49
  50         error = xfs_attr_get(ip, (unsigned char *)name, value, &asize, xflags);
  51         if (error)
  52                 return error;
  53         return asize;
  54 }
  55
  56 static int
  57 xfs_xattr_set(struct dentry *dentry, const char *name, const void *value,
  58                 size_t size, int flags, int xflags)
  59 {
  60         struct xfs_inode *ip = XFS_I(d_inode(dentry));
  61
  62         if (strcmp(name, "") == 0)
  63                 return -EINVAL;
  64
  65         /* Convert Linux syscall to XFS internal ATTR flags */
  66         if (flags & XATTR_CREATE)
  67                 xflags |= ATTR_CREATE;
  68         if (flags & XATTR_REPLACE)
  69                 xflags |= ATTR_REPLACE;
  70
  71         if (!value)
  72                 return xfs_attr_remove(ip, (unsigned char *)name, xflags);
  73         return xfs_attr_set(ip, (unsigned char *)name,
  74                                 (void *)value, size, xflags);
  75 }
  76
  77 static const struct xattr_handler xfs_xattr_user_handler = {
  78         .prefix = XATTR_USER_PREFIX,
  79         .flags  = 0, /* no flags implies user namespace */
  80         .get    = xfs_xattr_get,
  81         .set    = xfs_xattr_set,
  82 };
  83
  84 static const struct xattr_handler xfs_xattr_trusted_handler = {
  85         .prefix = XATTR_TRUSTED_PREFIX,
  86         .flags  = ATTR_ROOT,
  87         .get    = xfs_xattr_get,
  88         .set    = xfs_xattr_set,
  89 };
  90
  91 static const struct xattr_handler xfs_xattr_security_handler = {
  92         .prefix = XATTR_SECURITY_PREFIX,
  93         .flags  = ATTR_SECURE,
  94         .get    = xfs_xattr_get,
  95         .set    = xfs_xattr_set,
  96 };
  97
  98 const struct xattr_handler *xfs_xattr_handlers[] = {
  99         &xfs_xattr_user_handler,
 100         &xfs_xattr_trusted_handler,
 101         &xfs_xattr_security_handler,
 102 #ifdef CONFIG_XFS_POSIX_ACL
 103         &posix_acl_access_xattr_handler,
 104         &posix_acl_default_xattr_handler,
 105 #endif
 106         NULL
 107 };
 108
 109 static unsigned int xfs_xattr_prefix_len(int flags)
 110 {
 111         if (flags & XFS_ATTR_SECURE)
 112                 return sizeof("security");
 113         else if (flags & XFS_ATTR_ROOT)
 114                 return sizeof("trusted");
 115         else
 116                 return sizeof("user");
 117 }
 118
 119 static const char *xfs_xattr_prefix(int flags)
 120 {
 121         if (flags & XFS_ATTR_SECURE)
 122                 return xfs_xattr_security_handler.prefix;
 123         else if (flags & XFS_ATTR_ROOT)
 124                 return xfs_xattr_trusted_handler.prefix;
 125         else
 126                 return xfs_xattr_user_handler.prefix;
 127 }
 128
 129 static int
 130 xfs_xattr_put_listent(
 131         struct xfs_attr_list_context *context,
 132         int             flags,
 133         unsigned char   *name,
 134         int             namelen,
 135         int             valuelen,
 136         unsigned char   *value)
 137 {
 138         unsigned int prefix_len = xfs_xattr_prefix_len(flags);
 139         char *offset;
 140         int arraytop;
 141
 142         ASSERT(context->count >= 0);
 143
 144         /*
 145          * Only show root namespace entries if we are actually allowed to
 146          * see them.
 147          */
 148         if ((flags & XFS_ATTR_ROOT) && !capable(CAP_SYS_ADMIN))
 149                 return 0;
 150
 151         arraytop = context->count + prefix_len + namelen + 1;
 152         if (arraytop > context->firstu) {
 153                 context->count = -1;    /* insufficient space */
 154                 return 1;
 155         }
 156         offset = (char *)context->alist + context->count;
 157         strncpy(offset, xfs_xattr_prefix(flags), prefix_len);
 158         offset += prefix_len;
 159         strncpy(offset, (char *)name, namelen);                 /* real name */
 160         offset += namelen;
 161         *offset = '\0';
 162         context->count += prefix_len + namelen + 1;
 163         return 0;
 164 }
 165
 166 static int
 167 xfs_xattr_put_listent_sizes(
 168         struct xfs_attr_list_context *context,
 169         int             flags,
 170         unsigned char   *name,
 171         int             namelen,
 172         int             valuelen,
 173         unsigned char   *value)
 174 {
 175         context->count += xfs_xattr_prefix_len(flags) + namelen + 1;
 176         return 0;
 177 }
 178
 179 static int
 180 list_one_attr(const char *name, const size_t len, void *data,
 181                 size_t size, ssize_t *result)
 182 {
 183         char *p = data + *result;
 184
 185         *result += len;
 186         if (!size)
 187                 return 0;
 188         if (*result > size)
 189                 return -ERANGE;
 190
 191         strcpy(p, name);
 192         return 0;
 193 }
 194
 195 ssize_t
 196 xfs_vn_listxattr(struct dentry *dentry, char *data, size_t size)
 197 {
 198         struct xfs_attr_list_context context;
 199         struct attrlist_cursor_kern cursor = { 0 };
 200         struct inode            *inode = d_inode(dentry);
 201         int                     error;
 202
 203         /*
 204          * First read the regular on-disk attributes.
 205          */
 206         memset(&context, 0, sizeof(context));
 207         context.dp = XFS_I(inode);
 208         context.cursor = &cursor;
 209         context.resynch = 1;
 210         context.alist = data;
 211         context.bufsize = size;
 212         context.firstu = context.bufsize;
 213
 214         if (size)
 215                 context.put_listent = xfs_xattr_put_listent;
 216         else
 217                 context.put_listent = xfs_xattr_put_listent_sizes;
 218
 219         xfs_attr_list_int(&context);
 220         if (context.count < 0)
 221                 return -ERANGE;
 222
 223         /*
 224          * Then add the two synthetic ACL attributes.
 225          */
 226         if (posix_acl_access_exists(inode)) {
 227                 error = list_one_attr(POSIX_ACL_XATTR_ACCESS,
 228                                 strlen(POSIX_ACL_XATTR_ACCESS) + 1,
 229                                 data, size, &context.count);
 230                 if (error)
 231                         return error;
 232         }
 233
 234         if (posix_acl_default_exists(inode)) {
 235                 error = list_one_attr(POSIX_ACL_XATTR_DEFAULT,
 236                                 strlen(POSIX_ACL_XATTR_DEFAULT) + 1,
 237                                 data, size, &context.count);
 238                 if (error)
 239                         return error;
 240         }
 241
 242         return context.count;
 243 }