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         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 void
  58 xfs_forget_acl(
  59         struct inode            *inode,
  60         const char              *name,
  61         int                     xflags)
  62 {
  63         /*
  64          * Invalidate any cached ACLs if the user has bypassed the ACL
  65          * interface. We don't validate the content whatsoever so it is caller
  66          * responsibility to provide data in valid format and ensure i_mode is
  67          * consistent.
  68          */
  69         if (xflags & ATTR_ROOT) {
  70 #ifdef CONFIG_XFS_POSIX_ACL
  71                 if (!strcmp(name, SGI_ACL_FILE))
  72                         forget_cached_acl(inode, ACL_TYPE_ACCESS);
  73                 else if (!strcmp(name, SGI_ACL_DEFAULT))
  74                         forget_cached_acl(inode, ACL_TYPE_DEFAULT);
  75 #endif
  76         }
  77 }
  78
  79 static int
  80 xfs_xattr_set(const struct xattr_handler *handler, struct dentry *dentry,
  81                 const char *name, const void *value, size_t size, int flags)
  82 {
  83         int                     xflags = handler->flags;
  84         struct xfs_inode        *ip = XFS_I(d_inode(dentry));
  85         int                     error;
  86
  87         if (strcmp(name, "") == 0)
  88                 return -EINVAL;
  89
  90         /* Convert Linux syscall to XFS internal ATTR flags */
  91         if (flags & XATTR_CREATE)
  92                 xflags |= ATTR_CREATE;
  93         if (flags & XATTR_REPLACE)
  94                 xflags |= ATTR_REPLACE;
  95
  96         if (!value)
  97                 return xfs_attr_remove(ip, (unsigned char *)name, xflags);
  98         error = xfs_attr_set(ip, (unsigned char *)name,
  99                                 (void *)value, size, xflags);
 100         if (!error)
 101                 xfs_forget_acl(d_inode(dentry), name, xflags);
 102
 103         return error;
 104 }
 105
 106 static const struct xattr_handler xfs_xattr_user_handler = {
 107         .prefix = XATTR_USER_PREFIX,
 108         .flags  = 0, /* no flags implies user namespace */
 109         .get    = xfs_xattr_get,
 110         .set    = xfs_xattr_set,
 111 };
 112
 113 static const struct xattr_handler xfs_xattr_trusted_handler = {
 114         .prefix = XATTR_TRUSTED_PREFIX,
 115         .flags  = ATTR_ROOT,
 116         .get    = xfs_xattr_get,
 117         .set    = xfs_xattr_set,
 118 };
 119
 120 static const struct xattr_handler xfs_xattr_security_handler = {
 121         .prefix = XATTR_SECURITY_PREFIX,
 122         .flags  = ATTR_SECURE,
 123         .get    = xfs_xattr_get,
 124         .set    = xfs_xattr_set,
 125 };
 126
 127 const struct xattr_handler *xfs_xattr_handlers[] = {
 128         &xfs_xattr_user_handler,
 129         &xfs_xattr_trusted_handler,
 130         &xfs_xattr_security_handler,
 131 #ifdef CONFIG_XFS_POSIX_ACL
 132         &posix_acl_access_xattr_handler,
 133         &posix_acl_default_xattr_handler,
 134 #endif
 135         NULL
 136 };
 137
 138 static unsigned int xfs_xattr_prefix_len(int flags)
 139 {
 140         if (flags & XFS_ATTR_SECURE)
 141                 return sizeof("security");
 142         else if (flags & XFS_ATTR_ROOT)
 143                 return sizeof("trusted");
 144         else
 145                 return sizeof("user");
 146 }
 147
 148 static const char *xfs_xattr_prefix(int flags)
 149 {
 150         if (flags & XFS_ATTR_SECURE)
 151                 return xfs_xattr_security_handler.prefix;
 152         else if (flags & XFS_ATTR_ROOT)
 153                 return xfs_xattr_trusted_handler.prefix;
 154         else
 155                 return xfs_xattr_user_handler.prefix;
 156 }
 157
 158 static int
 159 xfs_xattr_put_listent(
 160         struct xfs_attr_list_context *context,
 161         int             flags,
 162         unsigned char   *name,
 163         int             namelen,
 164         int             valuelen,
 165         unsigned char   *value)
 166 {
 167         unsigned int prefix_len = xfs_xattr_prefix_len(flags);
 168         char *offset;
 169         int arraytop;
 170
 171         ASSERT(context->count >= 0);
 172
 173         /*
 174          * Only show root namespace entries if we are actually allowed to
 175          * see them.
 176          */
 177         if ((flags & XFS_ATTR_ROOT) && !capable(CAP_SYS_ADMIN))
 178                 return 0;
 179
 180         arraytop = context->count + prefix_len + namelen + 1;
 181         if (arraytop > context->firstu) {
 182                 context->count = -1;    /* insufficient space */
 183                 context->seen_enough = 1;
 184                 return 0;
 185         }
 186         offset = (char *)context->alist + context->count;
 187         strncpy(offset, xfs_xattr_prefix(flags), prefix_len);
 188         offset += prefix_len;
 189         strncpy(offset, (char *)name, namelen);                 /* real name */
 190         offset += namelen;
 191         *offset = '\0';
 192         context->count += prefix_len + namelen + 1;
 193         return 0;
 194 }
 195
 196 static int
 197 xfs_xattr_put_listent_sizes(
 198         struct xfs_attr_list_context *context,
 199         int             flags,
 200         unsigned char   *name,
 201         int             namelen,
 202         int             valuelen,
 203         unsigned char   *value)
 204 {
 205         context->count += xfs_xattr_prefix_len(flags) + namelen + 1;
 206         return 0;
 207 }
 208
 209 static int
 210 list_one_attr(const char *name, const size_t len, void *data,
 211                 size_t size, ssize_t *result)
 212 {
 213         char *p = data + *result;
 214
 215         *result += len;
 216         if (!size)
 217                 return 0;
 218         if (*result > size)
 219                 return -ERANGE;
 220
 221         strcpy(p, name);
 222         return 0;
 223 }
 224
 225 ssize_t
 226 xfs_vn_listxattr(
 227         struct dentry   *dentry,
 228         char            *data,
 229         size_t          size)
 230 {
 231         struct xfs_attr_list_context context;
 232         struct attrlist_cursor_kern cursor = { 0 };
 233         struct inode    *inode = d_inode(dentry);
 234         int             error;
 235
 236         /*
 237          * First read the regular on-disk attributes.
 238          */
 239         memset(&context, 0, sizeof(context));
 240         context.dp = XFS_I(inode);
 241         context.cursor = &cursor;
 242         context.resynch = 1;
 243         context.alist = data;
 244         context.bufsize = size;
 245         context.firstu = context.bufsize;
 246
 247         if (size)
 248                 context.put_listent = xfs_xattr_put_listent;
 249         else
 250                 context.put_listent = xfs_xattr_put_listent_sizes;
 251
 252         error = xfs_attr_list_int(&context);
 253         if (error)
 254                 return error;
 255         if (context.count < 0)
 256                 return -ERANGE;
 257
 258         /*
 259          * Then add the two synthetic ACL attributes.
 260          */
 261         if (posix_acl_access_exists(inode)) {
 262                 error = list_one_attr(POSIX_ACL_XATTR_ACCESS,
 263                                 strlen(POSIX_ACL_XATTR_ACCESS) + 1,
 264                                 data, size, &context.count);
 265                 if (error)
 266                         return error;
 267         }
 268
 269         if (posix_acl_default_exists(inode)) {
 270                 error = list_one_attr(POSIX_ACL_XATTR_DEFAULT,
 271                                 strlen(POSIX_ACL_XATTR_DEFAULT) + 1,
 272                                 data, size, &context.count);
 273                 if (error)
 274                         return error;
 275         }
 276
 277         return context.count;
 278 }