source/modules/vfs_acl_xattr.c

   1 /*
   2  * Store Windows ACLs in xattrs.
   3  *
   4  * Copyright (C) Volker Lendecke, 2008
   5  * Copyright (C) Jeremy Allison, 2008
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 3 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 /* NOTE: This is an experimental module, not yet finished. JRA. */
  22
  23 #include "includes.h"
  24 #include "librpc/gen_ndr/xattr.h"
  25 #include "librpc/gen_ndr/ndr_xattr.h"
  26
  27 #undef DBGC_CLASS
  28 #define DBGC_CLASS DBGC_VFS
  29
  30 static NTSTATUS parse_acl_blob(const DATA_BLOB *pblob,
  31                                 const struct timespec cts,
  32                                 uint32 security_info,
  33                                 struct security_descriptor **ppdesc)
  34 {
  35         TALLOC_CTX *ctx = talloc_tos();
  36         struct xattr_NTACL xacl;
  37         enum ndr_err_code ndr_err;
  38         size_t sd_size;
  39         struct timespec ts;
  40
  41         ndr_err = ndr_pull_struct_blob(pblob, ctx, &xacl,
  42                         (ndr_pull_flags_fn_t)ndr_pull_xattr_NTACL);
  43
  44         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
  45                 DEBUG(5, ("parse_acl_blob: ndr_pull_xattr_NTACL failed: %s\n",
  46                         ndr_errstr(ndr_err)));
  47                 return ndr_map_error2ntstatus(ndr_err);;
  48         }
  49
  50         if (xacl.version != 2) {
  51                 return NT_STATUS_REVISION_MISMATCH;
  52         }
  53
  54         /*
  55          * Check that the ctime timestamp is ealier
  56          * than the stored timestamp.
  57          */
  58
  59         ts = nt_time_to_unix_timespec(&xacl.info.sd_ts->last_changed);
  60
  61         if (timespec_compare(&cts, &ts) > 0) {
  62                 DEBUG(5, ("parse_acl_blob: stored ACL out of date.\n"));
  63                 return NT_STATUS_EA_CORRUPT_ERROR;
  64         }
  65
  66         *ppdesc = make_sec_desc(ctx, SEC_DESC_REVISION, SEC_DESC_SELF_RELATIVE,
  67                         (security_info & OWNER_SECURITY_INFORMATION)
  68                         ? xacl.info.sd_ts->sd->owner_sid : NULL,
  69                         (security_info & GROUP_SECURITY_INFORMATION)
  70                         ? xacl.info.sd_ts->sd->group_sid : NULL,
  71                         (security_info & SACL_SECURITY_INFORMATION)
  72                         ? xacl.info.sd_ts->sd->sacl : NULL,
  73                         (security_info & DACL_SECURITY_INFORMATION)
  74                         ? xacl.info.sd_ts->sd->dacl : NULL,
  75                         &sd_size);
  76
  77         TALLOC_FREE(xacl.info.sd);
  78
  79         return (*ppdesc != NULL) ? NT_STATUS_OK : NT_STATUS_NO_MEMORY;
  80 }
  81
  82 static NTSTATUS get_acl_blob(TALLOC_CTX *ctx,
  83                         vfs_handle_struct *handle,
  84                         files_struct *fsp,
  85                         const char *name,
  86                         DATA_BLOB *pblob)
  87 {
  88         size_t size = 1024;
  89         uint8_t *val = NULL;
  90         uint8_t *tmp;
  91         ssize_t sizeret;
  92         int saved_errno;
  93
  94         ZERO_STRUCTP(pblob);
  95
  96   again:
  97
  98         tmp = TALLOC_REALLOC_ARRAY(ctx, val, uint8_t, size);
  99         if (tmp == NULL) {
 100                 TALLOC_FREE(val);
 101                 return NT_STATUS_NO_MEMORY;
 102         }
 103         val = tmp;
 104
 105         become_root();
 106         if (fsp && fsp->fh->fd != -1) {
 107                 sizeret = SMB_VFS_FGETXATTR(fsp, XATTR_NTACL_NAME, val, size);
 108         } else {
 109                 sizeret = SMB_VFS_GETXATTR(handle->conn, name,
 110                                         XATTR_NTACL_NAME, val, size);
 111         }
 112         if (sizeret == -1) {
 113                 saved_errno = errno;
 114         }
 115         unbecome_root();
 116
 117         /* Max ACL size is 65536 bytes. */
 118         if (sizeret == -1) {
 119                 errno = saved_errno;
 120                 if ((errno == ERANGE) && (size != 65536)) {
 121                         /* Too small, try again. */
 122                         size = 65536;
 123                         goto again;
 124                 }
 125
 126                 /* Real error - exit here. */
 127                 TALLOC_FREE(val);
 128                 return map_nt_error_from_unix(errno);
 129         }
 130
 131         pblob->data = val;
 132         pblob->length = sizeret;
 133         return NT_STATUS_OK;
 134 }
 135
 136 static NTSTATUS get_nt_acl_xattr_internal(vfs_handle_struct *handle,
 137                                         files_struct *fsp,
 138                                         const char *name,
 139                                         uint32 security_info,
 140                                         SEC_DESC **ppdesc)
 141 {
 142         TALLOC_CTX *ctx = talloc_tos();
 143         DATA_BLOB blob;
 144         SMB_STRUCT_STAT sbuf;
 145         NTSTATUS status;
 146
 147         if (fsp && name == NULL) {
 148                 name = fsp->fsp_name;
 149         }
 150
 151         DEBUG(10, ("get_nt_acl_xattr_internal: name=%s\n", name));
 152
 153         status = get_acl_blob(ctx, handle, fsp, name, &blob);
 154         if (!NT_STATUS_IS_OK(status)) {
 155                 DEBUG(10, ("get_acl_blob returned %s\n", nt_errstr(status)));
 156                 return status;
 157         }
 158
 159         if (fsp && fsp->fh->fd != -1) {
 160                 if (SMB_VFS_FSTAT(fsp, &sbuf) == -1) {
 161                         return map_nt_error_from_unix(errno);
 162                 }
 163         } else {
 164                 if (SMB_VFS_STAT(handle->conn, name, &sbuf) == -1) {
 165                         return map_nt_error_from_unix(errno);
 166                 }
 167         }
 168
 169         status = parse_acl_blob(&blob, get_ctimespec(&sbuf),
 170                         security_info, ppdesc);
 171         if (!NT_STATUS_IS_OK(status)) {
 172                 DEBUG(10, ("parse_acl_blob returned %s\n",
 173                                 nt_errstr(status)));
 174                 return status;
 175         }
 176
 177         TALLOC_FREE(blob.data);
 178         return status;
 179 }
 180
 181 static int mkdir_acl_xattr(vfs_handle_struct *handle,  const char *path, mode_t mode)
 182 {
 183         return SMB_VFS_NEXT_MKDIR(handle, path, mode);
 184 }
 185
 186 /*********************************************************************
 187  * Currently this only works for existing files. Need to work on
 188  * inheritance for new files.
 189 *********************************************************************/
 190
 191 static int open_acl_xattr(vfs_handle_struct *handle,  const char *fname, files_struct *fsp, int flags, mode_t mode)
 192 {
 193         uint32_t access_granted = 0;
 194         SEC_DESC *pdesc = NULL;
 195         NTSTATUS status = get_nt_acl_xattr_internal(handle,
 196                                         NULL,
 197                                         fname,
 198                                         (OWNER_SECURITY_INFORMATION |
 199                                          GROUP_SECURITY_INFORMATION |
 200                                          DACL_SECURITY_INFORMATION),
 201                                         &pdesc);
 202         if (NT_STATUS_IS_OK(status)) {
 203                 /* See if we can access it. */
 204                 if (!se_access_check(pdesc,
 205                                         handle->conn->server_info->ptok,
 206                                         fsp->access_mask,
 207                                         &access_granted,
 208                                         &status)) {
 209                         errno = map_errno_from_nt_status(status);
 210                         return -1;
 211                 }
 212         }
 213
 214         return SMB_VFS_NEXT_OPEN(handle, fname, fsp, flags, mode);
 215 }
 216
 217 static NTSTATUS fget_nt_acl_xattr(vfs_handle_struct *handle, files_struct *fsp,
 218         uint32 security_info, SEC_DESC **ppdesc)
 219 {
 220         NTSTATUS status = get_nt_acl_xattr_internal(handle, fsp,
 221                                 NULL, security_info, ppdesc);
 222         if (NT_STATUS_IS_OK(status)) {
 223                 return NT_STATUS_OK;
 224         }
 225         return SMB_VFS_NEXT_FGET_NT_ACL(handle, fsp,
 226                         security_info, ppdesc);
 227 }
 228
 229 static NTSTATUS get_nt_acl_xattr(vfs_handle_struct *handle,
 230         const char *name, uint32 security_info, SEC_DESC **ppdesc)
 231 {
 232         NTSTATUS status = get_nt_acl_xattr_internal(handle, NULL,
 233                                 name, security_info, ppdesc);
 234         if (NT_STATUS_IS_OK(status)) {
 235                 return NT_STATUS_OK;
 236         }
 237         return SMB_VFS_NEXT_GET_NT_ACL(handle, name,
 238                         security_info, ppdesc);
 239 }
 240
 241 static NTSTATUS create_acl_blob(const SEC_DESC *psd, DATA_BLOB *pblob)
 242 {
 243         struct xattr_NTACL xacl;
 244         struct security_descriptor_timestamp sd_ts;
 245         enum ndr_err_code ndr_err;
 246         TALLOC_CTX *ctx = talloc_tos();
 247         struct timespec curr = timespec_current();
 248
 249         ZERO_STRUCT(xacl);
 250         ZERO_STRUCT(sd_ts);
 251
 252         /* Horrid hack as setting an xattr changes the ctime
 253          * on Linux. This gives a race of 1 second during
 254          * which we would not see a POSIX ACL set.
 255          */
 256         curr.tv_sec += 1;
 257
 258         xacl.version = 2;
 259         xacl.info.sd_ts = &sd_ts;
 260         xacl.info.sd_ts->sd = CONST_DISCARD(SEC_DESC *, psd);
 261         unix_timespec_to_nt_time(&xacl.info.sd_ts->last_changed, curr);
 262
 263         ndr_err = ndr_push_struct_blob(
 264                         pblob, ctx, &xacl,
 265                         (ndr_push_flags_fn_t)ndr_push_xattr_NTACL);
 266
 267         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 268                 DEBUG(5, ("create_acl_blob: ndr_push_xattr_NTACL failed: %s\n",
 269                         ndr_errstr(ndr_err)));
 270                 return ndr_map_error2ntstatus(ndr_err);;
 271         }
 272
 273         return NT_STATUS_OK;
 274 }
 275
 276 static NTSTATUS store_acl_blob(files_struct *fsp,
 277                                 DATA_BLOB *pblob)
 278 {
 279         int ret;
 280         int saved_errno;
 281
 282         DEBUG(10,("store_acl_blob: storing blob length %u on file %s\n",
 283                         (unsigned int)pblob->length, fsp->fsp_name));
 284
 285         become_root();
 286         if (fsp->fh->fd != -1) {
 287                 ret = SMB_VFS_FSETXATTR(fsp, XATTR_NTACL_NAME,
 288                         pblob->data, pblob->length, 0);
 289         } else {
 290                 ret = SMB_VFS_SETXATTR(fsp->conn, fsp->fsp_name,
 291                                 XATTR_NTACL_NAME,
 292                                 pblob->data, pblob->length, 0);
 293         }
 294         if (ret) {
 295                 saved_errno = errno;
 296         }
 297         unbecome_root();
 298         if (ret) {
 299                 errno = saved_errno;
 300                 DEBUG(5, ("store_acl_blob: setting attr failed for file %s"
 301                         "with error %s\n",
 302                         fsp->fsp_name,
 303                         strerror(errno) ));
 304                 return map_nt_error_from_unix(errno);
 305         }
 306         return NT_STATUS_OK;
 307 }
 308
 309 static NTSTATUS fset_nt_acl_xattr(vfs_handle_struct *handle, files_struct *fsp,
 310         uint32 security_info_sent, const SEC_DESC *psd)
 311 {
 312         NTSTATUS status;
 313         DATA_BLOB blob;
 314
 315         status = SMB_VFS_NEXT_FSET_NT_ACL(handle, fsp, security_info_sent, psd);
 316         if (!NT_STATUS_IS_OK(status)) {
 317                 return status;
 318         }
 319
 320         create_acl_blob(psd, &blob);
 321         store_acl_blob(fsp, &blob);
 322
 323         return NT_STATUS_OK;
 324 }
 325
 326 /* VFS operations structure */
 327
 328 static vfs_op_tuple skel_op_tuples[] =
 329 {
 330         {SMB_VFS_OP(mkdir_acl_xattr), SMB_VFS_OP_MKDIR, SMB_VFS_LAYER_TRANSPARENT},
 331         {SMB_VFS_OP(open_acl_xattr),  SMB_VFS_OP_OPEN,  SMB_VFS_LAYER_TRANSPARENT},
 332
 333         /* NT File ACL operations */
 334
 335         {SMB_VFS_OP(fget_nt_acl_xattr),SMB_VFS_OP_FGET_NT_ACL,SMB_VFS_LAYER_TRANSPARENT},
 336         {SMB_VFS_OP(get_nt_acl_xattr), SMB_VFS_OP_GET_NT_ACL, SMB_VFS_LAYER_TRANSPARENT},
 337         {SMB_VFS_OP(fset_nt_acl_xattr),SMB_VFS_OP_FSET_NT_ACL,SMB_VFS_LAYER_TRANSPARENT},
 338
 339         {SMB_VFS_OP(NULL), SMB_VFS_OP_NOOP, SMB_VFS_LAYER_NOOP}
 340 };
 341
 342 NTSTATUS vfs_acl_xattr_init(void)
 343 {
 344         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "acl_xattr", skel_op_tuples);
 345 }