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