From: guenther <guenther@openbsd.org>
Date: Fri, 12 Nov 2021 22:28:13 +0000 (+0000)
Subject: Add support for RELR relocations in the executable and share objects.
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=b333198034bc11e2ce6282e0721c2c9371d8e4b7;p=openbsd

Add support for RELR relocations in the executable and share objects.
This doesn't affect ld.so's self-reloc, which still requires DT_REL/DT_RELA

ok kettenis@
---

diff --git a/libexec/ld.so/loader.c b/libexec/ld.so/loader.c
index db66346e41c..2063098a8b0 100644
--- a/libexec/ld.so/loader.c
+++ b/libexec/ld.so/loader.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: loader.c,v 1.192 2021/05/25 17:01:36 kn Exp $ */
+/*	$OpenBSD: loader.c,v 1.193 2021/11/12 22:28:13 guenther Exp $ */
 
 /*
  * Copyright (c) 1998 Per Fogelstrom, Opsycon AB
@@ -61,6 +61,7 @@ void _dl_call_init_recurse(elf_object_t *object, int initfirst);
 void _dl_clean_boot(void);
 static inline void unprotect_if_textrel(elf_object_t *_object);
 static inline void reprotect_if_textrel(elf_object_t *_object);
+static void _dl_rreloc(elf_object_t *_object);
 
 int _dl_pagesz __relro = 4096;
 int _dl_bindnow __relro = 0;
@@ -721,6 +722,7 @@ _dl_rtld(elf_object_t *object)
 	 * Do relocation information first, then GOT.
 	 */
 	unprotect_if_textrel(object);
+	_dl_rreloc(object);
 	fails =_dl_md_reloc(object, DT_REL, DT_RELSZ);
 	fails += _dl_md_reloc(object, DT_RELA, DT_RELASZ);
 	reprotect_if_textrel(object);
@@ -947,3 +949,35 @@ reprotect_if_textrel(elf_object_t *object)
 		}
 	}
 }
+
+static void
+_dl_rreloc(elf_object_t *object)
+{
+	const Elf_Relr	*reloc, *rend;
+	Elf_Addr	loff = object->obj_base;
+
+	reloc = object->dyn.relr;
+	rend  = (const Elf_Relr *)((char *)reloc + object->dyn.relrsz);
+
+	while (reloc < rend) {
+		Elf_Addr *where;
+
+		where = (Elf_Addr *)(*reloc + loff);
+		*where++ += loff;
+
+		for (reloc++; reloc < rend && (*reloc & 1); reloc++) {
+			Elf_Addr bits = *reloc >> 1;
+
+			Elf_Addr *here = where;
+			while (bits != 0) {
+				if (bits & 1) {
+					*here += loff;
+				}
+				bits >>= 1;
+				here++;
+			}
+			where += (8 * sizeof *reloc) - 1;
+		}
+	}
+}
+
diff --git a/libexec/ld.so/resolve.c b/libexec/ld.so/resolve.c
index 4d0928b4f2e..2879c331c3a 100644
--- a/libexec/ld.so/resolve.c
+++ b/libexec/ld.so/resolve.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: resolve.c,v 1.95 2021/06/02 07:29:03 semarie Exp $ */
+/*	$OpenBSD: resolve.c,v 1.96 2021/11/12 22:28:13 guenther Exp $ */
 
 /*
  * Copyright (c) 1998 Per Fogelstrom, Opsycon AB
@@ -368,6 +368,8 @@ _dl_finalize_object(const char *objname, Elf_Dyn *dynp, Elf_Phdr *phdrp,
 		object->Dyn.info[DT_FINI_ARRAY] += obase;
 	if (object->Dyn.info[DT_PREINIT_ARRAY])
 		object->Dyn.info[DT_PREINIT_ARRAY] += obase;
+	if (object->Dyn.info[DT_RELR])
+		object->Dyn.info[DT_RELR] += obase;
 
 	if (gnu_hash) {
 		Elf_Word *hashtab = (Elf_Word *)(gnu_hash + obase);
diff --git a/libexec/ld.so/resolve.h b/libexec/ld.so/resolve.h
index 7c14005a658..6b0d36b292c 100644
--- a/libexec/ld.so/resolve.h
+++ b/libexec/ld.so/resolve.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: resolve.h,v 1.98 2021/06/02 07:29:03 semarie Exp $ */
+/*	$OpenBSD: resolve.h,v 1.99 2021/11/12 22:28:13 guenther Exp $ */
 
 /*
  * Copyright (c) 1998 Per Fogelstrom, Opsycon AB
@@ -47,7 +47,7 @@
 #endif
 
 /* Number of low tags that are used saved internally (0 .. DT_NUM-1) */
-#define DT_NUM	(DT_PREINIT_ARRAYSZ + 1)
+#define DT_NUM	(DT_RELR + 1)
 
 struct load_list {
 	struct load_list *next;
@@ -132,6 +132,9 @@ struct elf_object {
 			Elf_Addr	encoding;
 			initarrayfunc	**preinit_array;
 			Elf_Addr	preinit_arraysz;
+			Elf_Addr	unassigned;
+			Elf_Addr	relrsz;
+			Elf_Relr	*relr;
 		} u;
 	} Dyn;
 #define dyn Dyn.u