From: Volker Lendecke <vl@samba.org>
Date: Thu, 3 Mar 2022 10:52:12 +0000 (+0100)
Subject: smbd: Pass dirfsp instead of a parent filename to unix_mode
X-Git-Tag: tevent-0.12.0~558
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f60ca2e2f35666583f2e8cd11cb507406bb17393;p=thirdparty%2Fsamba.git

smbd: Pass dirfsp instead of a parent filename to unix_mode

This converts a STAT (with potential symlink race problems) into an
FSTAT on the O_PATH fd we have for the directory

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

diff --git a/source3/smbd/dosmode.c b/source3/smbd/dosmode.c
index 68764b46ac8..f434b3875ca 100644
--- a/source3/smbd/dosmode.c
+++ b/source3/smbd/dosmode.c
@@ -106,7 +106,7 @@ static uint32_t filter_mode_by_protocol(uint32_t mode)
 
 mode_t unix_mode(connection_struct *conn, int dosmode,
 		 const struct smb_filename *smb_fname,
-		 struct smb_filename *smb_fname_parent)
+		 struct files_struct *parent_dirfsp)
 {
 	mode_t result = (S_IRUSR | S_IRGRP | S_IROTH | S_IWUSR | S_IWGRP | S_IWOTH);
 	mode_t dir_mode = 0; /* Mode of the inherit_from directory if
@@ -116,20 +116,24 @@ mode_t unix_mode(connection_struct *conn, int dosmode,
 		result &= ~(S_IWUSR | S_IWGRP | S_IWOTH);
 	}
 
-	if ((smb_fname_parent != NULL) && lp_inherit_permissions(SNUM(conn))) {
+	if ((parent_dirfsp != NULL) && lp_inherit_permissions(SNUM(conn))) {
+		struct stat_ex sbuf = { .st_ex_nlink = 0, };
+		int ret;
+
 		DBG_DEBUG("[%s] inheriting from [%s]\n",
 			  smb_fname_str_dbg(smb_fname),
-			  smb_fname_str_dbg(smb_fname_parent));
+			  smb_fname_str_dbg(parent_dirfsp->fsp_name));
 
-		if (SMB_VFS_STAT(conn, smb_fname_parent) != 0) {
-			DBG_ERR("stat failed [%s]: %s\n",
-				smb_fname_str_dbg(smb_fname_parent),
+		ret = SMB_VFS_FSTAT(parent_dirfsp, &sbuf);
+		if (ret != 0) {
+			DBG_ERR("fstat failed [%s]: %s\n",
+				smb_fname_str_dbg(parent_dirfsp->fsp_name),
 				strerror(errno));
 			return(0);      /* *** shouldn't happen! *** */
 		}
 
 		/* Save for later - but explicitly remove setuid bit for safety. */
-		dir_mode = smb_fname_parent->st.st_ex_mode & ~S_ISUID;
+		dir_mode = sbuf.st_ex_mode & ~S_ISUID;
 		DEBUG(2,("unix_mode(%s) inherit mode %o\n",
 			 smb_fname_str_dbg(smb_fname), (int)dir_mode));
 		/* Clear "result" */
@@ -973,7 +977,11 @@ int file_set_dosmode(connection_struct *conn,
 	}
 
 	/* Fall back to UNIX modes. */
-	unixmode = unix_mode(conn, dosmode, smb_fname, parent_dir);
+	unixmode = unix_mode(
+		conn,
+		dosmode,
+		smb_fname,
+		parent_dir != NULL ? parent_dir->fsp : NULL);
 
 	/* preserve the file type bits */
 	mask |= S_IFMT;
diff --git a/source3/smbd/open.c b/source3/smbd/open.c
index d4fce40d16e..baae51f157e 100644
--- a/source3/smbd/open.c
+++ b/source3/smbd/open.c
@@ -3513,8 +3513,11 @@ static NTSTATUS open_file_ntcreate(connection_struct *conn,
 
 		/* We add FILE_ATTRIBUTE_ARCHIVE to this as this mode is only used if the file is
 		 * created new. */
-		unx_mode = unix_mode(conn, new_dos_attributes | FILE_ATTRIBUTE_ARCHIVE,
-				     smb_fname, parent_dir_fname);
+		unx_mode = unix_mode(
+			conn,
+			new_dos_attributes | FILE_ATTRIBUTE_ARCHIVE,
+			smb_fname,
+			parent_dir_fname->fsp);
 	}
 
 	DEBUG(10, ("open_file_ntcreate: fname=%s, dos_attrs=0x%x "
@@ -4269,7 +4272,7 @@ static NTSTATUS mkdir_internal(connection_struct *conn,
 		mode = unix_mode(conn,
 				 FILE_ATTRIBUTE_DIRECTORY,
 				 smb_dname,
-				 parent_dir_fname);
+				 parent_dir_fname->fsp);
 	}
 
 	status = check_parent_access_fsp(parent_dir_fname->fsp, access_mask);
diff --git a/source3/smbd/proto.h b/source3/smbd/proto.h
index f880a223f7f..ac2f7be4bb5 100644
--- a/source3/smbd/proto.h
+++ b/source3/smbd/proto.h
@@ -265,7 +265,7 @@ bool smbd_setup_mdns_registration(struct tevent_context *ev,
 
 mode_t unix_mode(connection_struct *conn, int dosmode,
 		 const struct smb_filename *smb_fname,
-		 struct smb_filename *smb_fname_parent);
+		 struct files_struct *parent_dirfsp);
 uint32_t dos_mode_msdfs(connection_struct *conn,
 		      const struct smb_filename *smb_fname);
 uint32_t fdos_mode(struct files_struct *fsp);