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(const struct xattr_handler *handler, struct dentry *dentry,
  36                 const char *name, void *value, size_t size)
  37 {
  38         int xflags = handler->flags;
  39         struct xfs_inode *ip = XFS_I(d_inode(dentry));
  40         int error, asize = size;
  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 void
  55 xfs_forget_acl(
  56         struct inode            *inode,
  57         const char              *name,
  58         int                     xflags)
  59 {
  60         /*
  61          * Invalidate any cached ACLs if the user has bypassed the ACL
  62          * interface. We don't validate the content whatsoever so it is caller
  63          * responsibility to provide data in valid format and ensure i_mode is
  64          * consistent.
  65          */
  66         if (xflags & ATTR_ROOT) {
  67 #ifdef CONFIG_XFS_POSIX_ACL
  68                 if (!strcmp(name, SGI_ACL_FILE))
  69                         forget_cached_acl(inode, ACL_TYPE_ACCESS);
  70                 else if (!strcmp(name, SGI_ACL_DEFAULT))
  71                         forget_cached_acl(inode, ACL_TYPE_DEFAULT);
  72 #endif
  73         }
  74 }
  75
  76 static int
  77 xfs_xattr_set(const struct xattr_handler *handler, struct dentry *dentry,
  78                 const char *name, const void *value, size_t size, int flags)
  79 {
  80         int                     xflags = handler->flags;
  81         struct xfs_inode        *ip = XFS_I(d_inode(dentry));
  82         int                     error;
  83
  84         /* Convert Linux syscall to XFS internal ATTR flags */
  85         if (flags & XATTR_CREATE)
  86                 xflags |= ATTR_CREATE;
  87         if (flags & XATTR_REPLACE)
  88                 xflags |= ATTR_REPLACE;
  89
  90         if (!value)
  91                 return xfs_attr_remove(ip, (unsigned char *)name, xflags);
  92         error = xfs_attr_set(ip, (unsigned char *)name,
  93                                 (void *)value, size, xflags);
  94         if (!error)
  95                 xfs_forget_acl(d_inode(dentry), name, xflags);
  96
  97         return error;
  98 }
  99
 100 static const struct xattr_handler xfs_xattr_user_handler = {
 101         .prefix = XATTR_USER_PREFIX,
 102         .flags  = 0, /* no flags implies user namespace */
 103         .get    = xfs_xattr_get,
 104         .set    = xfs_xattr_set,
 105 };
 106
 107 static const struct xattr_handler xfs_xattr_trusted_handler = {
 108         .prefix = XATTR_TRUSTED_PREFIX,
 109         .flags  = ATTR_ROOT,
 110         .get    = xfs_xattr_get,
 111         .set    = xfs_xattr_set,
 112 };
 113
 114 static const struct xattr_handler xfs_xattr_security_handler = {
 115         .prefix = XATTR_SECURITY_PREFIX,
 116         .flags  = ATTR_SECURE,
 117         .get    = xfs_xattr_get,
 118         .set    = xfs_xattr_set,
 119 };
 120
 121 const struct xattr_handler *xfs_xattr_handlers[] = {
 122         &xfs_xattr_user_handler,
 123         &xfs_xattr_trusted_handler,
 124         &xfs_xattr_security_handler,
 125 #ifdef CONFIG_XFS_POSIX_ACL
 126         &posix_acl_access_xattr_handler,
 127         &posix_acl_default_xattr_handler,
 128 #endif
 129         NULL
 130 };
 131
 132 static unsigned int xfs_xattr_prefix_len(int flags)
 133 {
 134         if (flags & XFS_ATTR_SECURE)
 135                 return sizeof("security");
 136         else if (flags & XFS_ATTR_ROOT)
 137                 return sizeof("trusted");
 138         else
 139                 return sizeof("user");
 140 }
 141
 142 static const char *xfs_xattr_prefix(int flags)
 143 {
 144         if (flags & XFS_ATTR_SECURE)
 145                 return xfs_xattr_security_handler.prefix;
 146         else if (flags & XFS_ATTR_ROOT)
 147                 return xfs_xattr_trusted_handler.prefix;
 148         else
 149                 return xfs_xattr_user_handler.prefix;
 150 }
 151
 152 static int
 153 xfs_xattr_put_listent(
 154         struct xfs_attr_list_context *context,
 155         int             flags,
 156         unsigned char   *name,
 157         int             namelen,
 158         int             valuelen,
 159         unsigned char   *value)
 160 {
 161         unsigned int prefix_len = xfs_xattr_prefix_len(flags);
 162         char *offset;
 163         int arraytop;
 164
 165         ASSERT(context->count >= 0);
 166
 167         /*
 168          * Only show root namespace entries if we are actually allowed to
 169          * see them.
 170          */
 171         if ((flags & XFS_ATTR_ROOT) && !capable(CAP_SYS_ADMIN))
 172                 return 0;
 173
 174         arraytop = context->count + prefix_len + namelen + 1;
 175         if (arraytop > context->firstu) {
 176                 context->count = -1;    /* insufficient space */
 177                 return 1;
 178         }
 179         offset = (char *)context->alist + context->count;
 180         strncpy(offset, xfs_xattr_prefix(flags), prefix_len);
 181         offset += prefix_len;
 182         strncpy(offset, (char *)name, namelen);                 /* real name */
 183         offset += namelen;
 184         *offset = '\0';
 185         context->count += prefix_len + namelen + 1;
 186         return 0;
 187 }
 188
 189 static int
 190 xfs_xattr_put_listent_sizes(
 191         struct xfs_attr_list_context *context,
 192         int             flags,
 193         unsigned char   *name,
 194         int             namelen,
 195         int             valuelen,
 196         unsigned char   *value)
 197 {
 198         context->count += xfs_xattr_prefix_len(flags) + namelen + 1;
 199         return 0;
 200 }
 201
 202 static int
 203 list_one_attr(const char *name, const size_t len, void *data,
 204                 size_t size, ssize_t *result)
 205 {
 206         char *p = data + *result;
 207
 208         *result += len;
 209         if (!size)
 210                 return 0;
 211         if (*result > size)
 212                 return -ERANGE;
 213
 214         strcpy(p, name);
 215         return 0;
 216 }
 217
 218 ssize_t
 219 xfs_vn_listxattr(struct dentry *dentry, char *data, size_t size)
 220 {
 221         struct xfs_attr_list_context context;
 222         struct attrlist_cursor_kern cursor = { 0 };
 223         struct inode            *inode = d_inode(dentry);
 224         int                     error;
 225
 226         /*
 227          * First read the regular on-disk attributes.
 228          */
 229         memset(&context, 0, sizeof(context));
 230         context.dp = XFS_I(inode);
 231         context.cursor = &cursor;
 232         context.resynch = 1;
 233         context.alist = data;
 234         context.bufsize = size;
 235         context.firstu = context.bufsize;
 236
 237         if (size)
 238                 context.put_listent = xfs_xattr_put_listent;
 239         else
 240                 context.put_listent = xfs_xattr_put_listent_sizes;
 241
 242         xfs_attr_list_int(&context);
 243         if (context.count < 0)
 244                 return -ERANGE;
 245
 246         /*
 247          * Then add the two synthetic ACL attributes.
 248          */
 249         if (posix_acl_access_exists(inode)) {
 250                 error = list_one_attr(XATTR_NAME_POSIX_ACL_ACCESS,
 251                                 strlen(XATTR_NAME_POSIX_ACL_ACCESS) + 1,
 252                                 data, size, &context.count);
 253                 if (error)
 254                         return error;
 255         }
 256
 257         if (posix_acl_default_exists(inode)) {
 258                 error = list_one_attr(XATTR_NAME_POSIX_ACL_DEFAULT,
 259                                 strlen(XATTR_NAME_POSIX_ACL_DEFAULT) + 1,
 260                                 data, size, &context.count);
 261                 if (error)
 262                         return error;
 263         }
 264
 265         return context.count;
 266 }