Add a hook to enable load-time inspection of program headers

This hook can be used to perform additional compatibility checks
between shared libraries by inspecting custom program header
information.

	* elf/dl-machine-reject-phdr.h: New file.
	* elf/dl-load.c: #include that.
	(open_verify): Call elf_machine_reject_phdr_p and ignore the file
	if that returned true.

1 files changed, 34 insertions, 0 deletions

diff --git a/elf/dl-machine-reject-phdr.h b/elf/dl-machine-reject-phdr.h
new file mode 100644
index 0000000000..d110a32023
--- /dev/null
+++ b/elf/dl-machine-reject-phdr.h
@@ -0,0 +1,34 @@
+/* Machine-dependent program header inspection for the ELF loader.
+   Copyright (C) 2014 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _DL_MACHINE_REJECT_PHDR_H
+#define _DL_MACHINE_REJECT_PHDR_H 1
+
+#include <stdbool.h>
+
+/* Return true iff ELF program headers are incompatible with the running
+   host.  */
+static inline bool
+elf_machine_reject_phdr_p (const ElfW(Phdr) *phdr, uint_fast16_t phnum,
+			   const char *buf, size_t len, struct link_map *map,
+			   int fd)
+{
+  return false;
+}
+
+#endif /* dl-machine-reject-phdr.h */