fs/xfs/xfs_xattr.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2008 Christoph Hellwig.
   4  * Portions Copyright (C) 2000-2008 Silicon Graphics, Inc.
   5  */
   6
   7 #include "xfs.h"
   8 #include "xfs_shared.h"
   9 #include "xfs_format.h"
  10 #include "xfs_log_format.h"
  11 #include "xfs_da_format.h"
  12 #include "xfs_inode.h"
  13 #include "xfs_attr.h"
  14 #include "xfs_acl.h"
  15 #include "xfs_da_btree.h"
  16
  17 #include <linux/posix_acl_xattr.h>
  18
  19
  20 static int
  21 xfs_xattr_get(const struct xattr_handler *handler, struct dentry *unused,
  22                 struct inode *inode, const char *name, void *value, size_t size)
  23 {
  24         struct xfs_da_args      args = {
  25                 .dp             = XFS_I(inode),
  26                 .attr_filter    = handler->flags,
  27                 .name           = name,
  28                 .namelen        = strlen(name),
  29                 .value          = value,
  30                 .valuelen       = size,
  31         };
  32         int                     error;
  33
  34         error = xfs_attr_get(&args);
  35         if (error)
  36                 return error;
  37         return args.valuelen;
  38 }
  39
  40 static int
  41 xfs_xattr_set(const struct xattr_handler *handler,
  42               struct user_namespace *mnt_userns, struct dentry *unused,
  43               struct inode *inode, const char *name, const void *value,
  44               size_t size, int flags)
  45 {
  46         struct xfs_da_args      args = {
  47                 .dp             = XFS_I(inode),
  48                 .attr_filter    = handler->flags,
  49                 .attr_flags     = flags,
  50                 .name           = name,
  51                 .namelen        = strlen(name),
  52                 .value          = (void *)value,
  53                 .valuelen       = size,
  54         };
  55         int                     error;
  56
  57         error = xfs_attr_set(&args);
  58         if (!error && (handler->flags & XFS_ATTR_ROOT))
  59                 xfs_forget_acl(inode, name);
  60         return error;
  61 }
  62
  63 static const struct xattr_handler xfs_xattr_user_handler = {
  64         .prefix = XATTR_USER_PREFIX,
  65         .flags  = 0, /* no flags implies user namespace */
  66         .get    = xfs_xattr_get,
  67         .set    = xfs_xattr_set,
  68 };
  69
  70 static const struct xattr_handler xfs_xattr_trusted_handler = {
  71         .prefix = XATTR_TRUSTED_PREFIX,
  72         .flags  = XFS_ATTR_ROOT,
  73         .get    = xfs_xattr_get,
  74         .set    = xfs_xattr_set,
  75 };
  76
  77 static const struct xattr_handler xfs_xattr_security_handler = {
  78         .prefix = XATTR_SECURITY_PREFIX,
  79         .flags  = XFS_ATTR_SECURE,
  80         .get    = xfs_xattr_get,
  81         .set    = xfs_xattr_set,
  82 };
  83
  84 const struct xattr_handler *xfs_xattr_handlers[] = {
  85         &xfs_xattr_user_handler,
  86         &xfs_xattr_trusted_handler,
  87         &xfs_xattr_security_handler,
  88 #ifdef CONFIG_XFS_POSIX_ACL
  89         &posix_acl_access_xattr_handler,
  90         &posix_acl_default_xattr_handler,
  91 #endif
  92         NULL
  93 };
  94
  95 static void
  96 __xfs_xattr_put_listent(
  97         struct xfs_attr_list_context *context,
  98         char *prefix,
  99         int prefix_len,
 100         unsigned char *name,
 101         int namelen)
 102 {
 103         char *offset;
 104         int arraytop;
 105
 106         if (context->count < 0 || context->seen_enough)
 107                 return;
 108
 109         if (!context->buffer)
 110                 goto compute_size;
 111
 112         arraytop = context->count + prefix_len + namelen + 1;
 113         if (arraytop > context->firstu) {
 114                 context->count = -1;    /* insufficient space */
 115                 context->seen_enough = 1;
 116                 return;
 117         }
 118         offset = context->buffer + context->count;
 119         strncpy(offset, prefix, prefix_len);
 120         offset += prefix_len;
 121         strncpy(offset, (char *)name, namelen);                 /* real name */
 122         offset += namelen;
 123         *offset = '\0';
 124
 125 compute_size:
 126         context->count += prefix_len + namelen + 1;
 127         return;
 128 }
 129
 130 static void
 131 xfs_xattr_put_listent(
 132         struct xfs_attr_list_context *context,
 133         int             flags,
 134         unsigned char   *name,
 135         int             namelen,
 136         int             valuelen)
 137 {
 138         char *prefix;
 139         int prefix_len;
 140
 141         ASSERT(context->count >= 0);
 142
 143         if (flags & XFS_ATTR_ROOT) {
 144 #ifdef CONFIG_XFS_POSIX_ACL
 145                 if (namelen == SGI_ACL_FILE_SIZE &&
 146                     strncmp(name, SGI_ACL_FILE,
 147                             SGI_ACL_FILE_SIZE) == 0) {
 148                         __xfs_xattr_put_listent(
 149                                         context, XATTR_SYSTEM_PREFIX,
 150                                         XATTR_SYSTEM_PREFIX_LEN,
 151                                         XATTR_POSIX_ACL_ACCESS,
 152                                         strlen(XATTR_POSIX_ACL_ACCESS));
 153                 } else if (namelen == SGI_ACL_DEFAULT_SIZE &&
 154                          strncmp(name, SGI_ACL_DEFAULT,
 155                                  SGI_ACL_DEFAULT_SIZE) == 0) {
 156                         __xfs_xattr_put_listent(
 157                                         context, XATTR_SYSTEM_PREFIX,
 158                                         XATTR_SYSTEM_PREFIX_LEN,
 159                                         XATTR_POSIX_ACL_DEFAULT,
 160                                         strlen(XATTR_POSIX_ACL_DEFAULT));
 161                 }
 162 #endif
 163
 164                 /*
 165                  * Only show root namespace entries if we are actually allowed to
 166                  * see them.
 167                  */
 168                 if (!capable(CAP_SYS_ADMIN))
 169                         return;
 170
 171                 prefix = XATTR_TRUSTED_PREFIX;
 172                 prefix_len = XATTR_TRUSTED_PREFIX_LEN;
 173         } else if (flags & XFS_ATTR_SECURE) {
 174                 prefix = XATTR_SECURITY_PREFIX;
 175                 prefix_len = XATTR_SECURITY_PREFIX_LEN;
 176         } else {
 177                 prefix = XATTR_USER_PREFIX;
 178                 prefix_len = XATTR_USER_PREFIX_LEN;
 179         }
 180
 181         __xfs_xattr_put_listent(context, prefix, prefix_len, name,
 182                                 namelen);
 183         return;
 184 }
 185
 186 ssize_t
 187 xfs_vn_listxattr(
 188         struct dentry   *dentry,
 189         char            *data,
 190         size_t          size)
 191 {
 192         struct xfs_attr_list_context context;
 193         struct inode    *inode = d_inode(dentry);
 194         int             error;
 195
 196         /*
 197          * First read the regular on-disk attributes.
 198          */
 199         memset(&context, 0, sizeof(context));
 200         context.dp = XFS_I(inode);
 201         context.resynch = 1;
 202         context.buffer = size ? data : NULL;
 203         context.bufsize = size;
 204         context.firstu = context.bufsize;
 205         context.put_listent = xfs_xattr_put_listent;
 206
 207         error = xfs_attr_list(&context);
 208         if (error)
 209                 return error;
 210         if (context.count < 0)
 211                 return -ERANGE;
 212
 213         return context.count;
 214 }