s3: Add vfs_linux_xfs_sgid

http://oss.sgi.com/bugzilla/show_bug.cgi?id=280 shows an old Linux XFS bug that
still exists: Under certain circumstances the SGID bit is not inherited.

source3/Makefile.in

@@ -752,6 +752,7 @@ PERFCOUNT_TEST_OBJ = modules/perfcount_test.o
 VFS_DIRSORT_OBJ = modules/vfs_dirsort.o
 VFS_SCANNEDONLY_OBJ = modules/vfs_scannedonly.o
 VFS_CROSSRENAME_OBJ = modules/vfs_crossrename.o
+VFS_LINUX_XFS_SGID_OBJ = modules/vfs_linux_xfs_sgid.o
 
 PLAINTEXT_AUTH_OBJ = auth/pampass.o auth/pass_check.o
 
@@ -2833,6 +2834,10 @@ bin/crossrename.@SHLIBEXT@: $(BINARY_PREREQS) $(VFS_CROSSRENAME_OBJ)
 	@echo "Building plugin $@"
 	@$(SHLD_MODULE) $(VFS_CROSSRENAME_OBJ)
 
+bin/linux_xfs_sgid.@SHLIBEXT@: $(BINARY_PREREQS) $(VFS_LINUX_XFS_SGID_OBJ)
+	@echo "Building plugin $@"
+	@$(SHLD_MODULE) $(VFS_LINUX_XFS_SGID_OBJ)
+
 #########################################################
 ## IdMap NSS plugins
 

source3/configure.in

@@ -454,6 +454,7 @@ default_shared_modules="$default_shared_modules vfs_preopen"
 default_shared_modules="$default_shared_modules vfs_catia"
 default_shared_modules="$default_shared_modules vfs_scannedonly"
 default_shared_modules="$default_shared_modules vfs_crossrename"
+default_shared_modules="$default_shared_modules vfs_linux_xfs_sgid"
 
 if test "x$developer" = xyes; then
    default_static_modules="$default_static_modules rpc_rpcecho pdb_ads"
@@ -6576,6 +6577,7 @@ SMB_MODULE(vfs_onefs_shadow_copy, \$(VFS_ONEFS_SHADOW_COPY), "bin/onefs_shadow_c
 SMB_MODULE(vfs_dirsort, \$(VFS_DIRSORT_OBJ), "bin/dirsort.$SHLIBEXT", VFS)
 SMB_MODULE(vfs_scannedonly, \$(VFS_SCANNEDONLY_OBJ), "bin/scannedonly.$SHLIBEXT", VFS)
 SMB_MODULE(vfs_crossrename, \$(VFS_CROSSRENAME_OBJ), "bin/crossrename.$SHLIBEXT", VFS)
+SMB_MODULE(vfs_linux_xfs_sgid, \$(VFS_LINUX_XFS_SGID_OBJ), "bin/linux_xfs_sgid.$SHLIBEXT", VFS)
 
 SMB_SUBSYSTEM(VFS,smbd/vfs.o)
 

source3/modules/vfs_linux_xfs_sgid.c

@@ -0,0 +1,105 @@
+/*
+ * Module to work around a bug in Linux XFS:
+ * http://oss.sgi.com/bugzilla/show_bug.cgi?id=280
+ *
+ * Copyright (c) Volker Lendecke 2010
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "includes.h"
+
+static int linux_xfs_sgid_mkdir(vfs_handle_struct *handle,  const char *path, mode_t mode)
+{
+	struct smb_filename fname = { 0, };
+	int mkdir_res;
+	int res;
+
+	DEBUG(10, ("Calling linux_xfs_sgid_mkdir(%s)\n", path));
+
+	mkdir_res = SMB_VFS_NEXT_MKDIR(handle, path, mode);
+	if (mkdir_res == -1) {
+		DEBUG(10, ("SMB_VFS_NEXT_MKDIR returned error: %s\n",
+			   strerror(errno)));
+		return mkdir_res;
+	}
+
+	if (!parent_dirname(talloc_tos(), path, &fname.base_name, NULL)) {
+		DEBUG(1, ("parent_dirname failed\n"));
+		/* return success, we did the mkdir */
+		return mkdir_res;
+	}
+
+	res = SMB_VFS_NEXT_STAT(handle, &fname);
+	if (res == -1) {
+		DEBUG(10, ("NEXT_STAT(%s) failed: %s\n", fname.base_name,
+			   strerror(errno)));
+		/* return success, we did the mkdir */
+		return mkdir_res;
+	}
+	TALLOC_FREE(fname.base_name);
+	if ((fname.st.st_ex_mode & S_ISGID) == 0) {
+		/* No SGID to inherit */
+		DEBUG(10, ("No SGID to inherit\n"));
+		return mkdir_res;
+	}
+
+	fname.base_name = discard_const_p(char, path);
+
+	res = SMB_VFS_NEXT_STAT(handle, &fname);
+	if (res == -1) {
+		DEBUG(2, ("Could not stat just created dir %s: %s\n", path,
+			  strerror(errno)));
+		/* return success, we did the mkdir */
+		return mkdir_res;
+	}
+	fname.st.st_ex_mode |= S_ISGID;
+	fname.st.st_ex_mode &= ~S_IFDIR;
+
+	/*
+	 * Yes, we have to do this as root. If you do it as
+	 * non-privileged user, XFS on Linux will just ignore us and
+	 * return success. What can you do...
+	 */
+	become_root();
+	res = SMB_VFS_NEXT_CHMOD(handle, path, fname.st.st_ex_mode);
+	unbecome_root();
+
+	if (res == -1) {
+		DEBUG(2, ("CHMOD(%s, %o) failed: %s\n", path,
+			  (int)fname.st.st_ex_mode, strerror(errno)));
+		/* return success, we did the mkdir */
+		return mkdir_res;
+	}
+	return mkdir_res;
+}
+
+static int linux_xfs_sgid_chmod_acl(vfs_handle_struct *handle,
+				    const char *name, mode_t mode)
+{
+	errno = ENOSYS;
+	return -1;
+}
+
+static struct vfs_fn_pointers linux_xfs_sgid_fns = {
+	.mkdir = linux_xfs_sgid_mkdir,
+	.chmod_acl = linux_xfs_sgid_chmod_acl,
+};
+
+NTSTATUS vfs_linux_xfs_sgid_init(void);
+NTSTATUS vfs_linux_xfs_sgid_init(void)
+{
+	return smb_register_vfs(SMB_VFS_INTERFACE_VERSION,
+				"linux_xfs_sgid", &linux_xfs_sgid_fns);
+}