source3/modules/vfs_linux_xfs_sgid.c

   1 /*
   2  * Module to work around a bug in Linux XFS:
   3  * http://oss.sgi.com/bugzilla/show_bug.cgi?id=280
   4  *
   5  * Copyright (c) Volker Lendecke 2010
   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 #include "includes.h"
  22 #include "system/filesys.h"
  23 #include "smbd/smbd.h"
  24
  25 static int linux_xfs_sgid_mkdirat(vfs_handle_struct *handle,
  26                 struct files_struct *dirfsp,
  27                 const struct smb_filename *smb_fname,
  28                 mode_t mode)
  29 {
  30         struct smb_filename fname = { 0, };
  31         int mkdir_res;
  32         int res;
  33
  34         DEBUG(10, ("Calling linux_xfs_sgid_mkdirat(%s)\n",
  35                 smb_fname->base_name));
  36
  37         mkdir_res = SMB_VFS_NEXT_MKDIRAT(handle,
  38                         dirfsp,
  39                         smb_fname,
  40                         mode);
  41         if (mkdir_res == -1) {
  42                 DEBUG(10, ("SMB_VFS_NEXT_MKDIRAT returned error: %s\n",
  43                            strerror(errno)));
  44                 return mkdir_res;
  45         }
  46
  47         if (!parent_dirname(talloc_tos(),
  48                         smb_fname->base_name,
  49                         &fname.base_name,
  50                         NULL)) {
  51                 DEBUG(1, ("parent_dirname failed\n"));
  52                 /* return success, we did the mkdir */
  53                 return mkdir_res;
  54         }
  55
  56         res = SMB_VFS_NEXT_STAT(handle, &fname);
  57         if (res == -1) {
  58                 DEBUG(10, ("NEXT_STAT(%s) failed: %s\n", fname.base_name,
  59                            strerror(errno)));
  60                 /* return success, we did the mkdir */
  61                 return mkdir_res;
  62         }
  63         TALLOC_FREE(fname.base_name);
  64         if ((fname.st.st_ex_mode & S_ISGID) == 0) {
  65                 /* No SGID to inherit */
  66                 DEBUG(10, ("No SGID to inherit\n"));
  67                 return mkdir_res;
  68         }
  69
  70         fname.base_name = discard_const_p(char, smb_fname->base_name);
  71
  72         res = SMB_VFS_NEXT_STAT(handle, &fname);
  73         if (res == -1) {
  74                 DEBUG(2, ("Could not stat just created dir %s: %s\n",
  75                         smb_fname->base_name,
  76                         strerror(errno)));
  77                 /* return success, we did the mkdir */
  78                 return mkdir_res;
  79         }
  80         fname.st.st_ex_mode |= S_ISGID;
  81         fname.st.st_ex_mode &= ~S_IFDIR;
  82
  83         /*
  84          * Yes, we have to do this as root. If you do it as
  85          * non-privileged user, XFS on Linux will just ignore us and
  86          * return success. What can you do...
  87          */
  88         become_root();
  89         res = SMB_VFS_NEXT_CHMOD(handle,
  90                         smb_fname,
  91                         fname.st.st_ex_mode);
  92         unbecome_root();
  93
  94         if (res == -1) {
  95                 DEBUG(2, ("CHMOD(%s, %o) failed: %s\n", smb_fname->base_name,
  96                           (int)fname.st.st_ex_mode, strerror(errno)));
  97                 /* return success, we did the mkdir */
  98                 return mkdir_res;
  99         }
 100         return mkdir_res;
 101 }
 102
 103 static struct vfs_fn_pointers linux_xfs_sgid_fns = {
 104         .mkdirat_fn = linux_xfs_sgid_mkdirat,
 105 };
 106
 107 static_decl_vfs;
 108 NTSTATUS vfs_linux_xfs_sgid_init(TALLOC_CTX *ctx)
 109 {
 110         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION,
 111                                 "linux_xfs_sgid", &linux_xfs_sgid_fns);
 112 }