From: Volker Lendecke <vl@samba.org>
Date: Sun, 13 Mar 2022 09:48:12 +0000 (+0100)
Subject: smbd: Add openat_internal_dir_from_pathref()
X-Git-Tag: talloc-2.3.4~331
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=df29512b72f652728afd6ce161e4eec50c2400a8;p=thirdparty%2Fsamba.git

smbd: Add openat_internal_dir_from_pathref()

If we have a directory pathref fsp, do an openat(dirfd, ".", O_RDONLY)
to cheaply get a real directory handle.

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
---

diff --git a/source3/smbd/files.c b/source3/smbd/files.c
index 542f1fe4181..caee85a674e 100644
--- a/source3/smbd/files.c
+++ b/source3/smbd/files.c
@@ -282,6 +282,56 @@ NTSTATUS open_internal_dirfsp(connection_struct *conn,
 	return NT_STATUS_OK;
 }
 
+/*
+ * Convert a pathref dirfsp into a real fsp. No need to do any cwd
+ * tricks, we just open ".".
+ */
+NTSTATUS openat_internal_dir_from_pathref(
+	struct files_struct *dirfsp,
+	int open_flags,
+	struct files_struct **_fsp)
+{
+	struct connection_struct *conn = dirfsp->conn;
+	struct smb_filename *smb_dname = dirfsp->fsp_name;
+	struct files_struct *fsp = NULL;
+	char dot[] = ".";
+	struct smb_filename smb_dot = {
+		.base_name = dot,
+		.flags = smb_dname->flags,
+		.twrp = smb_dname->twrp,
+	};
+	NTSTATUS status;
+
+	SMB_ASSERT(dirfsp != conn->cwd_fsp);
+	SMB_ASSERT(VALID_STAT(smb_dname->st));
+	SMB_ASSERT(S_ISDIR(smb_dname->st.st_ex_mode));
+	SMB_ASSERT(fsp_get_pathref_fd(dirfsp) != -1);
+
+	status = create_internal_dirfsp(conn, smb_dname, &fsp);
+	if (!NT_STATUS_IS_OK(status)) {
+		return status;
+	}
+
+	/*
+	 * Pointless for opening ".", but you never know...
+	 */
+	open_flags |= O_NOFOLLOW;
+
+	status = fd_openat(dirfsp, &smb_dot, fsp, open_flags, 0);
+	if (!NT_STATUS_IS_OK(status)) {
+		DBG_INFO("fd_openat(\"%s\", \".\") failed: %s\n",
+			 fsp_str_dbg(dirfsp),
+			 nt_errstr(status));
+		file_free(NULL, fsp);
+		return status;
+	}
+
+	fsp->fsp_name->st = smb_dname->st;
+	fsp->file_id = vfs_file_id_from_sbuf(conn, &fsp->fsp_name->st);
+	*_fsp = fsp;
+	return NT_STATUS_OK;
+}
+
 /*
  * The "link" in the name doesn't imply link in the filesystem
  * sense. It's a object that "links" together an fsp and an smb_fname
diff --git a/source3/smbd/proto.h b/source3/smbd/proto.h
index b78111c25c2..b6449b105f3 100644
--- a/source3/smbd/proto.h
+++ b/source3/smbd/proto.h
@@ -439,6 +439,10 @@ NTSTATUS open_internal_dirfsp(connection_struct *conn,
 			      const struct smb_filename *smb_dname,
 			      int open_flags,
 			      struct files_struct **_fsp);
+NTSTATUS openat_internal_dir_from_pathref(
+	struct files_struct *dirfsp,
+	int open_flags,
+	struct files_struct **_fsp);
 
 NTSTATUS openat_pathref_fsp(const struct files_struct *dirfsp,
 			    struct smb_filename *smb_fname);