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_ag.h"
  25 #include "xfs_mount.h"
  26 #include "xfs_da_format.h"
  27 #include "xfs_inode.h"
  28 #include "xfs_attr.h"
  29 #include "xfs_attr_leaf.h"
  30 #include "xfs_acl.h"
  31
  32 #include <linux/posix_acl_xattr.h>
  33 #include <linux/xattr.h>
  34
  35
  36 static int
  37 xfs_xattr_get(struct dentry *dentry, const char *name,
  38                 void *value, size_t size, int xflags)
  39 {
  40         struct xfs_inode *ip = XFS_I(dentry->d_inode);
  41         int error, asize = size;
  42
  43         if (strcmp(name, "") == 0)
  44                 return -EINVAL;
  45
  46         /* Convert Linux syscall to XFS internal ATTR flags */
  47         if (!size) {
  48                 xflags |= ATTR_KERNOVAL;
  49                 value = NULL;
  50         }
  51
  52         error = -xfs_attr_get(ip, (unsigned char *)name, value, &asize, xflags);
  53         if (error)
  54                 return error;
  55         return asize;
  56 }
  57
  58 static int
  59 xfs_xattr_set(struct dentry *dentry, const char *name, const void *value,
  60                 size_t size, int flags, int xflags)
  61 {
  62         struct xfs_inode *ip = XFS_I(dentry->d_inode);
  63
  64         if (strcmp(name, "") == 0)
  65                 return -EINVAL;
  66
  67         /* Convert Linux syscall to XFS internal ATTR flags */
  68         if (flags & XATTR_CREATE)
  69                 xflags |= ATTR_CREATE;
  70         if (flags & XATTR_REPLACE)
  71                 xflags |= ATTR_REPLACE;
  72
  73         if (!value)
  74                 return -xfs_attr_remove(ip, (unsigned char *)name, xflags);
  75         return -xfs_attr_set(ip, (unsigned char *)name,
  76                                 (void *)value, size, xflags);
  77 }
  78
  79 static const struct xattr_handler xfs_xattr_user_handler = {
  80         .prefix = XATTR_USER_PREFIX,
  81         .flags  = 0, /* no flags implies user namespace */
  82         .get    = xfs_xattr_get,
  83         .set    = xfs_xattr_set,
  84 };
  85
  86 static const struct xattr_handler xfs_xattr_trusted_handler = {
  87         .prefix = XATTR_TRUSTED_PREFIX,
  88         .flags  = ATTR_ROOT,
  89         .get    = xfs_xattr_get,
  90         .set    = xfs_xattr_set,
  91 };
  92
  93 static const struct xattr_handler xfs_xattr_security_handler = {
  94         .prefix = XATTR_SECURITY_PREFIX,
  95         .flags  = ATTR_SECURE,
  96         .get    = xfs_xattr_get,
  97         .set    = xfs_xattr_set,
  98 };
  99
 100 const struct xattr_handler *xfs_xattr_handlers[] = {
 101         &xfs_xattr_user_handler,
 102         &xfs_xattr_trusted_handler,
 103         &xfs_xattr_security_handler,
 104 #ifdef CONFIG_XFS_POSIX_ACL
 105         &posix_acl_access_xattr_handler,
 106         &posix_acl_default_xattr_handler,
 107 #endif
 108         NULL
 109 };
 110
 111 static unsigned int xfs_xattr_prefix_len(int flags)
 112 {
 113         if (flags & XFS_ATTR_SECURE)
 114                 return sizeof("security");
 115         else if (flags & XFS_ATTR_ROOT)
 116                 return sizeof("trusted");
 117         else
 118                 return sizeof("user");
 119 }
 120
 121 static const char *xfs_xattr_prefix(int flags)
 122 {
 123         if (flags & XFS_ATTR_SECURE)
 124                 return xfs_xattr_security_handler.prefix;
 125         else if (flags & XFS_ATTR_ROOT)
 126                 return xfs_xattr_trusted_handler.prefix;
 127         else
 128                 return xfs_xattr_user_handler.prefix;
 129 }
 130
 131 static int
 132 xfs_xattr_put_listent(
 133         struct xfs_attr_list_context *context,
 134         int             flags,
 135         unsigned char   *name,
 136         int             namelen,
 137         int             valuelen,
 138         unsigned char   *value)
 139 {
 140         unsigned int prefix_len = xfs_xattr_prefix_len(flags);
 141         char *offset;
 142         int arraytop;
 143
 144         ASSERT(context->count >= 0);
 145
 146         /*
 147          * Only show root namespace entries if we are actually allowed to
 148          * see them.
 149          */
 150         if ((flags & XFS_ATTR_ROOT) && !capable(CAP_SYS_ADMIN))
 151                 return 0;
 152
 153         arraytop = context->count + prefix_len + namelen + 1;
 154         if (arraytop > context->firstu) {
 155                 context->count = -1;    /* insufficient space */
 156                 return 1;
 157         }
 158         offset = (char *)context->alist + context->count;
 159         strncpy(offset, xfs_xattr_prefix(flags), prefix_len);
 160         offset += prefix_len;
 161         strncpy(offset, (char *)name, namelen);                 /* real name */
 162         offset += namelen;
 163         *offset = '\0';
 164         context->count += prefix_len + namelen + 1;
 165         return 0;
 166 }
 167
 168 static int
 169 xfs_xattr_put_listent_sizes(
 170         struct xfs_attr_list_context *context,
 171         int             flags,
 172         unsigned char   *name,
 173         int             namelen,
 174         int             valuelen,
 175         unsigned char   *value)
 176 {
 177         context->count += xfs_xattr_prefix_len(flags) + namelen + 1;
 178         return 0;
 179 }
 180
 181 static int
 182 list_one_attr(const char *name, const size_t len, void *data,
 183                 size_t size, ssize_t *result)
 184 {
 185         char *p = data + *result;
 186
 187         *result += len;
 188         if (!size)
 189                 return 0;
 190         if (*result > size)
 191                 return -ERANGE;
 192
 193         strcpy(p, name);
 194         return 0;
 195 }
 196
 197 ssize_t
 198 xfs_vn_listxattr(struct dentry *dentry, char *data, size_t size)
 199 {
 200         struct xfs_attr_list_context context;
 201         struct attrlist_cursor_kern cursor = { 0 };
 202         struct inode            *inode = dentry->d_inode;
 203         int                     error;
 204
 205         /*
 206          * First read the regular on-disk attributes.
 207          */
 208         memset(&context, 0, sizeof(context));
 209         context.dp = XFS_I(inode);
 210         context.cursor = &cursor;
 211         context.resynch = 1;
 212         context.alist = data;
 213         context.bufsize = size;
 214         context.firstu = context.bufsize;
 215
 216         if (size)
 217                 context.put_listent = xfs_xattr_put_listent;
 218         else
 219                 context.put_listent = xfs_xattr_put_listent_sizes;
 220
 221         xfs_attr_list_int(&context);
 222         if (context.count < 0)
 223                 return -ERANGE;
 224
 225         /*
 226          * Then add the two synthetic ACL attributes.
 227          */
 228         if (posix_acl_access_exists(inode)) {
 229                 error = list_one_attr(POSIX_ACL_XATTR_ACCESS,
 230                                 strlen(POSIX_ACL_XATTR_ACCESS) + 1,
 231                                 data, size, &context.count);
 232                 if (error)
 233                         return error;
 234         }
 235
 236         if (posix_acl_default_exists(inode)) {
 237                 error = list_one_attr(POSIX_ACL_XATTR_DEFAULT,
 238                                 strlen(POSIX_ACL_XATTR_DEFAULT) + 1,
 239                                 data, size, &context.count);
 240                 if (error)
 241                         return error;
 242         }
 243
 244         return context.count;
 245 }