Finish ld.so's transition to GNU_RELRO: eliminate support for using

__got_{start,end} to find a region to mark read-only.  It was only used
for binaries that didn't have a GNU_RELRO segment, but all archs have
been using that for over a year.  Since support for insecure-PLT layouts
on powerpc and alpha have been removed, all archs handle GNU_RELRO the
same way and the support can be moved from the MD code to the MI code.

ok mpi@

14 files changed, 38 insertions, 139 deletions

diff --git a/libexec/ld.so/aarch64/rtld_machine.c b/libexec/ld.so/aarch64/rtld_machine.c
index cfd3f474d7f..7630b58d85f 100644
--- a/libexec/ld.so/aarch64/rtld_machine.c
+++ b/libexec/ld.so/aarch64/rtld_machine.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rtld_machine.c,v 1.6 2018/10/25 16:41:38 guenther Exp $ */
+/*	$OpenBSD: rtld_machine.c,v 1.7 2018/11/16 21:15:47 guenther Exp $ */
 
 /*
  * Copyright (c) 2004 Dale Rahn
@@ -310,9 +310,6 @@ _dl_md_reloc_got(elf_object_t *object, int lazy)
 		pltgot[2] = (Elf_Addr)_dl_bind_start;
 	}
 
-	/* mprotect the GOT */
-	_dl_protect_segment(object, 0, "__got_start", "__got_end", PROT_READ);
-
 	return (fails);
 }
 
diff --git a/libexec/ld.so/alpha/rtld_machine.c b/libexec/ld.so/alpha/rtld_machine.c
index ca18c487bfb..0cb712d2533 100644
--- a/libexec/ld.so/alpha/rtld_machine.c
+++ b/libexec/ld.so/alpha/rtld_machine.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rtld_machine.c,v 1.63 2018/11/12 02:33:42 guenther Exp $ */
+/*	$OpenBSD: rtld_machine.c,v 1.64 2018/11/16 21:15:47 guenther Exp $ */
 
 /*
  * Copyright (c) 1999 Dale Rahn
@@ -294,9 +294,6 @@ _dl_md_reloc_got(elf_object_t *object, int lazy)
 		pltgot[1] = (Elf_Addr)object;
 	}
 
-	/* mprotect the GOT */
-	_dl_protect_segment(object, 0, "__got_start", "__got_end", PROT_READ);
-
 	return (fails);
 }
 
diff --git a/libexec/ld.so/amd64/rtld_machine.c b/libexec/ld.so/amd64/rtld_machine.c
index dd14f4b6b66..156ed28a9b6 100644
--- a/libexec/ld.so/amd64/rtld_machine.c
+++ b/libexec/ld.so/amd64/rtld_machine.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rtld_machine.c,v 1.29 2018/10/25 16:41:38 guenther Exp $ */
+/*	$OpenBSD: rtld_machine.c,v 1.30 2018/11/16 21:15:47 guenther Exp $ */
 
 /*
  * Copyright (c) 2002,2004 Dale Rahn
@@ -413,8 +413,5 @@ _dl_md_reloc_got(elf_object_t *object, int lazy)
 		}
 	}
 
-	/* mprotect the GOT */
-	_dl_protect_segment(object, 0, "__got_start", "__got_end", PROT_READ);
-
 	return (fails);
 }
diff --git a/libexec/ld.so/arm/rtld_machine.c b/libexec/ld.so/arm/rtld_machine.c
index e4fbea70ebc..797f09c8e7a 100644
--- a/libexec/ld.so/arm/rtld_machine.c
+++ b/libexec/ld.so/arm/rtld_machine.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rtld_machine.c,v 1.27 2018/10/25 16:41:38 guenther Exp $ */
+/*	$OpenBSD: rtld_machine.c,v 1.28 2018/11/16 21:15:47 guenther Exp $ */
 
 /*
  * Copyright (c) 2004 Dale Rahn
@@ -373,9 +373,6 @@ _dl_md_reloc_got(elf_object_t *object, int lazy)
 		pltgot[2] = (Elf_Addr)_dl_bind_start;
 	}
 
-	/* mprotect the GOT */
-	_dl_protect_segment(object, 0, "__got_start", "__got_end", PROT_READ);
-
 	return (fails);
 }
 
diff --git a/libexec/ld.so/hppa/rtld_machine.c b/libexec/ld.so/hppa/rtld_machine.c
index 46c91d9139c..0c11b75c269 100644
--- a/libexec/ld.so/hppa/rtld_machine.c
+++ b/libexec/ld.so/hppa/rtld_machine.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rtld_machine.c,v 1.36 2017/01/24 07:48:37 guenther Exp $	*/
+/*	$OpenBSD: rtld_machine.c,v 1.37 2018/11/16 21:15:47 guenther Exp $	*/
 
 /*
  * Copyright (c) 2004 Michael Shalayeff
@@ -428,10 +428,6 @@ _dl_md_reloc_got(elf_object_t *object, int lazy)
 		}
 	}
 
-	/* mprotect the GOT */
-	_dl_protect_segment(object, 0, "__got_start", "__got_end",
-	    PROT_READ|PROT_EXEC);
-
 	return (fails);
 }
 
diff --git a/libexec/ld.so/i386/rtld_machine.c b/libexec/ld.so/i386/rtld_machine.c
index a420f670114..5c35ac02523 100644
--- a/libexec/ld.so/i386/rtld_machine.c
+++ b/libexec/ld.so/i386/rtld_machine.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rtld_machine.c,v 1.38 2018/10/25 16:41:38 guenther Exp $ */
+/*	$OpenBSD: rtld_machine.c,v 1.39 2018/11/16 21:15:47 guenther Exp $ */
 
 /*
  * Copyright (c) 2002 Dale Rahn
@@ -440,8 +440,5 @@ _dl_md_reloc_got(elf_object_t *object, int lazy)
 		}
 	}
 
-	/* mprotect the GOT */
-	_dl_protect_segment(object, 0, "__got_start", "__got_end", PROT_READ);
-
 	return (fails);
 }
diff --git a/libexec/ld.so/loader.c b/libexec/ld.so/loader.c
index 625adb75412..abbe1f05051 100644
--- a/libexec/ld.so/loader.c
+++ b/libexec/ld.so/loader.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: loader.c,v 1.174 2018/10/23 04:01:45 guenther Exp $ */
+/*	$OpenBSD: loader.c,v 1.175 2018/11/16 21:15:47 guenther Exp $ */
 
 /*
  * Copyright (c) 1998 Per Fogelstrom, Opsycon AB
@@ -689,6 +689,17 @@ _dl_rtld(elf_object_t *object)
 	    object->obj_flags & DF_1_NOW));
 
 	/*
+	 * Handle GNU_RELRO
+	 */
+	if (object->relro_addr != 0 && object->relro_size != 0) {
+		Elf_Addr addr = object->relro_addr;
+
+		DL_DEB(("protect RELRO [0x%lx,0x%lx) in %s\n",
+		    addr, addr + object->relro_size, object->load_name));
+		_dl_mprotect((void *)addr, object->relro_size, PROT_READ);
+	}
+
+	/*
 	 * Look for W&X segments and make them read-only.
 	 */
 	for (llist = object->load_list; llist != NULL; llist = llist->next) {
diff --git a/libexec/ld.so/m88k/rtld_machine.c b/libexec/ld.so/m88k/rtld_machine.c
index 3579ebcc349..c818426f23b 100644
--- a/libexec/ld.so/m88k/rtld_machine.c
+++ b/libexec/ld.so/m88k/rtld_machine.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rtld_machine.c,v 1.22 2018/11/09 06:16:37 guenther Exp $	*/
+/*	$OpenBSD: rtld_machine.c,v 1.23 2018/11/16 21:15:47 guenther Exp $	*/
 
 /*
  * Copyright (c) 2013 Miodrag Vallat.
@@ -282,7 +282,6 @@ _dl_md_reloc_got(elf_object_t *object, int lazy)
 	int	fails = 0;
 	Elf_Addr *pltgot = (Elf_Addr *)object->Dyn.info[DT_PLTGOT];
 	Elf_Addr plt_start, plt_end;
-	size_t plt_size;
 
 	if (pltgot == NULL)
 		return (0);
@@ -296,19 +295,6 @@ _dl_md_reloc_got(elf_object_t *object, int lazy)
 	if (object->traced)
 		lazy = 1;
 
-	plt_start = object->Dyn.info[DT_88K_PLTSTART - DT_LOPROC + DT_NUM];
-	plt_end = object->Dyn.info[DT_88K_PLTEND - DT_LOPROC + DT_NUM];
-
-	/*
-	 * GOT relocation will require PLT to be writeable.
-	 */
-	if ((!lazy || object->obj_base != 0) && plt_start != 0 &&
-	    plt_end != 0) {
-		plt_size = plt_end - plt_start;
-		plt_start += object->obj_base;
-	} else
-		plt_size = 0;
-
 	if (!lazy) {
 		fails = _dl_md_reloc(object, DT_JMPREL, DT_PLTRELSZ);
 	} else {
@@ -330,15 +316,18 @@ _dl_md_reloc_got(elf_object_t *object, int lazy)
 		}
 	}
 
-	/* mprotect the GOT */
-	_dl_protect_segment(object, 0, "__got_start", "__got_end", PROT_READ);
-
-	if (plt_size != 0) {
-		/*
-		 * Force a cache sync on the whole plt here,
-		 * otherwise I$ might have stale information.
-		 */
-		_dl_cacheflush(plt_start, plt_size);
+	/*
+	 * Force a cache sync here on the whole PLT if we updated it
+	 * (and have the DT entries to find what we need to flush),
+	 * otherwise I$ might have stale information.
+	 */
+	plt_start = object->Dyn.info[DT_88K_PLTSTART - DT_LOPROC + DT_NUM];
+	plt_end = object->Dyn.info[DT_88K_PLTEND - DT_LOPROC + DT_NUM];
+	if ((!lazy || object->obj_base != 0) && plt_start != 0 &&
+	    plt_end != 0) {
+		size_t plt_size = plt_end - plt_start;
+		if (plt_size != 0)
+			_dl_cacheflush(plt_start + object->obj_base, plt_size);
 	}
 
 	return (fails);
diff --git a/libexec/ld.so/mips64/rtld_machine.c b/libexec/ld.so/mips64/rtld_machine.c
index fbc6d93a173..2e14ec9f0a9 100644
--- a/libexec/ld.so/mips64/rtld_machine.c
+++ b/libexec/ld.so/mips64/rtld_machine.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rtld_machine.c,v 1.28 2018/01/18 08:17:39 guenther Exp $ */
+/*	$OpenBSD: rtld_machine.c,v 1.29 2018/11/16 21:15:47 guenther Exp $ */
 
 /*
  * Copyright (c) 1998-2004 Opsycon AB, Sweden.
@@ -254,9 +254,6 @@ _dl_md_reloc_got(elf_object_t *object, int lazy)
 	}
 	object->status |= STAT_GOT_DONE;
 
-	/* mprotect the GOT */
-	_dl_protect_segment(object, 0, "__got_start", "__got_end", PROT_READ);
-
 	return (0);
 }
 
diff --git a/libexec/ld.so/powerpc/rtld_machine.c b/libexec/ld.so/powerpc/rtld_machine.c
index 7bf409bf4dd..8601401551d 100644
--- a/libexec/ld.so/powerpc/rtld_machine.c
+++ b/libexec/ld.so/powerpc/rtld_machine.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rtld_machine.c,v 1.64 2018/11/09 05:31:57 guenther Exp $ */
+/*	$OpenBSD: rtld_machine.c,v 1.65 2018/11/16 21:15:47 guenther Exp $ */
 
 /*
  * Copyright (c) 1999 Dale Rahn
@@ -377,9 +377,6 @@ _dl_md_reloc_got(elf_object_t *object, int lazy)
 			plt[i] += object->obj_base;
 	}
 
-	/* mprotect the GOT */
-	_dl_protect_segment(object, 0, "__got_start", "__got_end", PROT_READ);
-
 	return (fails);
 }
 
diff --git a/libexec/ld.so/resolve.c b/libexec/ld.so/resolve.c
index 0f192982d00..e1df6956e4b 100644
--- a/libexec/ld.so/resolve.c
+++ b/libexec/ld.so/resolve.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: resolve.c,v 1.85 2018/11/16 05:05:44 guenther Exp $ */
+/*	$OpenBSD: resolve.c,v 1.86 2018/11/16 21:15:47 guenther Exp $ */
 
 /*
  * Copyright (c) 1998 Per Fogelstrom, Opsycon AB
@@ -468,70 +468,6 @@ _dl_remove_object(elf_object_t *object)
 	free_objects = object;
 }
 
-/*
- * mprotect a segment to the indicated protection.  If 'addr' is non-zero,
- * then it's the start address, else the value of 'start_sym' is the start.
- * The value of 'end_sym' is the end address.  The start is rounded down
- * and the end is rounded up to page boundaries.  Returns 'addr' or the
- * address of the start symbol.
- */
-void *
-_dl_protect_segment(elf_object_t *object, Elf_Addr addr,
-    const char *start_sym, const char *end_sym, int prot)
-{
-	const Elf_Sym *this;
-	Elf_Addr ooff, start, end;
-
-	if (addr == 0 && start_sym[2] == 'g' &&
-	    (addr = object->relro_addr) != 0) {
-		DL_DEB(("protect start RELRO = 0x%lx in %s\n",
-		    addr, object->load_name));
-	}
-	else if (addr == 0) {
-		this = NULL;
-		ooff = _dl_find_symbol(start_sym, &this,
-		    SYM_SEARCH_OBJ | SYM_NOWARNNOTFOUND | SYM_PLT, NULL,
-		    object, NULL);
-		/* If not found, nothing to do */
-		if (this == NULL) {
-			DL_DEB(("protect start \"%s\" not found in %s\n",
-			    start_sym, object->load_name));
-			return (NULL);
-		}
-		addr = ooff + this->st_value;
-		DL_DEB(("protect start \"%s\" to %x = 0x%lx in %s\n",
-		    start_sym, prot, addr, object->load_name));
-	}
-
-	if (object->relro_addr != 0 && start_sym[2] == 'g') {
-		end = object->relro_addr + object->relro_size;
-		DL_DEB(("protect end RELRO = 0x%lx in %s\n",
-		    end, object->load_name));
-	} else {
-		this = NULL;
-		ooff = _dl_find_symbol(end_sym, &this,
-		    SYM_SEARCH_OBJ | SYM_NOWARNNOTFOUND | SYM_PLT, NULL,
-		    object, NULL);
-		if (this == NULL) {
-			DL_DEB(("protect end \"%s\" not found in %s\n",
-			    end_sym, object->load_name));
-			addr = 0;
-		} else {
-			end = ooff + this->st_value;
-			DL_DEB(("protect end \"%s\" = 0x%lx in %s\n",
-			    end_sym, end, object->load_name));
-		}
-	}
-
-	if (addr != 0 && addr < end) {
-		start = ELF_TRUNC(addr, _dl_pagesz);
-		end = ELF_ROUND(end, _dl_pagesz);
-		_dl_mprotect((void *)start, end - start, prot);
-	}
-
-	return ((void *)addr);
-}
-
 
 sym_cache *_dl_symcache;
 int _dl_symcachestat_hits;
@@ -684,10 +620,7 @@ _dl_find_symbol(const char *name, const Elf_Sym **this,
 		if (_dl_find_symbol_obj(req_obj, &sl))
 			goto found;
 
-	if (flags & SYM_SEARCH_OBJ) {
-		_dl_find_symbol_obj(req_obj, &sl);
-		/* always just fallthrough to 'found' */
-	} else if (flags & SYM_DLSYM) {
+	if (flags & SYM_DLSYM) {
 		if (_dl_find_symbol_obj(req_obj, &sl))
 			goto found;
 
diff --git a/libexec/ld.so/resolve.h b/libexec/ld.so/resolve.h
index 89e34b9cd85..ff0738dfa6a 100644
--- a/libexec/ld.so/resolve.h
+++ b/libexec/ld.so/resolve.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: resolve.h,v 1.85 2018/10/23 04:01:45 guenther Exp $ */
+/*	$OpenBSD: resolve.h,v 1.86 2018/11/16 21:15:47 guenther Exp $ */
 
 /*
  * Copyright (c) 1998 Per Fogelstrom, Opsycon AB
@@ -197,8 +197,6 @@ elf_object_t *_dl_finalize_object(const char *objname, Elf_Dyn *dynp,
     const long obase);
 void	_dl_remove_object(elf_object_t *object);
 void	_dl_cleanup_objects(void);
-void	*_dl_protect_segment(elf_object_t *_object, Elf_Addr _addr,
-	    const char *_start_sym, const char *_end_sym, int _prot);
 
 elf_object_t *_dl_load_shlib(const char *, elf_object_t *, int, int);
 elf_object_t *_dl_tryload_shlib(const char *libname, int type, int flags);
@@ -230,7 +228,6 @@ Elf_Addr _dl_find_symbol_bysym(elf_object_t *req_obj, unsigned int symidx,
 #define SYM_SEARCH_SELF		0x01
 #define SYM_SEARCH_OTHER	0x02
 #define SYM_SEARCH_NEXT		0x04
-#define SYM_SEARCH_OBJ		0x08
 /* warnnotfound */
 #define SYM_NOWARNNOTFOUND	0x00
 #define SYM_WARNNOTFOUND	0x10
diff --git a/libexec/ld.so/sh/rtld_machine.c b/libexec/ld.so/sh/rtld_machine.c
index bf13720dffb..37fbabf0718 100644
--- a/libexec/ld.so/sh/rtld_machine.c
+++ b/libexec/ld.so/sh/rtld_machine.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rtld_machine.c,v 1.26 2018/10/25 16:41:38 guenther Exp $ */
+/*	$OpenBSD: rtld_machine.c,v 1.27 2018/11/16 21:15:47 guenther Exp $ */
 
 /*
  * Copyright (c) 2004 Dale Rahn
@@ -825,9 +825,6 @@ _dl_md_reloc_got(elf_object_t *object, int lazy)
 		pltgot[2] = (Elf_Addr)_dl_bind_start;
 	}
 
-	/* mprotect the GOT */
-	_dl_protect_segment(object, 0, "__got_start", "__got_end", PROT_READ);
-
 	return (fails);
 }
 
diff --git a/libexec/ld.so/sparc64/rtld_machine.c b/libexec/ld.so/sparc64/rtld_machine.c
index 02a4ba2c9c3..f106011606e 100644
--- a/libexec/ld.so/sparc64/rtld_machine.c
+++ b/libexec/ld.so/sparc64/rtld_machine.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rtld_machine.c,v 1.62 2018/10/25 16:41:38 guenther Exp $ */
+/*	$OpenBSD: rtld_machine.c,v 1.63 2018/11/16 21:15:47 guenther Exp $ */
 
 /*
  * Copyright (c) 1999 Dale Rahn
@@ -850,8 +850,5 @@ _dl_md_reloc_got(elf_object_t *object, int lazy)
 		pltgot[8] = (Elf_Addr)object;
 	}
 
-	/* mprotect the GOT */
-	_dl_protect_segment(object, 0, "__got_start", "__got_end", PROT_READ);
-
 	return (fails);
 }