Update.

2004-01-13  Ulrich Drepper  <drepper@redhat.com>

	* Makeconfig: Define relro-LDFLAGS if have-z-relro==yes.  Add it to
	LDFLAGS.so and LDFLAGS-rtld.
	(+link): Add relro-LDFLAGS.
	* Makeconfig (shlib.lds): Place __libc_subfreeres, __libc_atexit, and
	__libc_thread_subfreeres sections after .jcr section.
	* config.make.in: Add have-z-relro.
	* configure.in: Add check for -z relro option.
	* include/link.h (struct link_map): Add relro_addr and relro_size
	members.
	* elf/dl-load.c (_dl_map_object_from_fd): Recognize PT_GNU_RELRO.
	* elf/dl-reloc.c (_dl_relocate_object): At the end, make relro
	part of loaded segments read-only.
	* elf/elf.h: Define PT_GNU_RELRO.
	* elf/rtld.c (_dl_start): Recognize PT_GNU_RELRO of ld.so.
	(dl_main): Recognize PT_GNU_RELRO of the application.  Call
	_dl_debug_initialize and initialize l_info[DT_DEBUG] before
	relocations.

4 files changed, 74 insertions, 40 deletions

diff --git a/elf/dl-load.c b/elf/dl-load.c
index c7e3716..dc993a5 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -1,5 +1,5 @@
 /* Map in a shared object's segments from the file.
-   Copyright (C) 1995-2002, 2003 Free Software Foundation, Inc.
+   Copyright (C) 1995-2002, 2003, 2004 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
@@ -1065,6 +1065,11 @@ cannot allocate TLS data structures for initial thread");
 	case PT_GNU_STACK:
 	  stack_flags = ph->p_flags;
 	  break;
+
+	case PT_GNU_RELRO:
+	  l->l_relro_addr = ph->p_vaddr;
+	  l->l_relro_size = ph->p_memsz;
+	  break;
 	}
 
     if (__builtin_expect (nloadcmds == 0, 0))
diff --git a/elf/dl-reloc.c b/elf/dl-reloc.c
index e5abba4..21d1871 100644
--- a/elf/dl-reloc.c
+++ b/elf/dl-reloc.c
@@ -1,5 +1,5 @@
 /* Relocate a shared object and resolve its references to other loaded objects.
-   Copyright (C) 1995-2002, 2003 Free Software Foundation, Inc.
+   Copyright (C) 1995-2002, 2003, 2004 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
@@ -307,6 +307,24 @@ _dl_relocate_object (struct link_map *l, struct r_scope_elem *scope[],
 
       textrels = textrels->next;
     }
+
+  /* In case we can protect the data now that the relocations are
+     done, do it.  */
+  if (l->l_relro_size != 0)
+    {
+      ElfW(Addr) start = ((l->l_addr + l->l_relro_addr)
+			  & ~(GL(dl_pagesize) - 1));
+      ElfW(Addr) end = ((l->l_addr + l->l_relro_addr + l->l_relro_size)
+			& ~(GL(dl_pagesize) - 1));
+
+      if (start != end
+	  && __mprotect ((void *) start, end - start, PROT_READ) < 0)
+	{
+	  errstring = N_("\
+cannot apply additional memory protection after relocation");
+	  goto call_error;
+	}
+    }
 }
 INTDEF (_dl_relocate_object)
 
diff --git a/elf/elf.h b/elf/elf.h
index 56b711d..9a4da65 100644
--- a/elf/elf.h
+++ b/elf/elf.h
@@ -1,5 +1,5 @@
 /* This file defines standard ELF types, structures, and macros.
-   Copyright (C) 1995-1999,2000,2001,2002,2003 Free Software Foundation, Inc.
+   Copyright (C) 1995-2003, 2004 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
@@ -567,6 +567,7 @@ typedef struct
 #define PT_LOOS		0x60000000	/* Start of OS-specific */
 #define PT_GNU_EH_FRAME	0x6474e550	/* GCC .eh_frame_hdr segment */
 #define PT_GNU_STACK	0x6474e551	/* Indicates stack executability */
+#define PT_GNU_RELRO	0x6474e552	/* Read-only after relocation */
 #define PT_LOSUNW	0x6ffffffa
 #define PT_SUNWBSS	0x6ffffffa	/* Sun Specific segment */
 #define PT_SUNWSTACK	0x6ffffffb	/* Stack segment */
diff --git a/elf/rtld.c b/elf/rtld.c
index 392ccb6..4273a6f 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -1,5 +1,5 @@
 /* Run time dynamic linker.
-   Copyright (C) 1995-2002, 2003 Free Software Foundation, Inc.
+   Copyright (C) 1995-2002, 2003, 2004 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
@@ -332,13 +332,14 @@ _dl_start (void *arg)
   bootstrap_map.l_tls_offset = NO_TLS_OFFSET;
 #endif
 
-#if USE___THREAD
   /* Get the dynamic linker's own program header.  First we need the ELF
      file header.  The `_begin' symbol created by the linker script points
      to it.  When we have something like GOTOFF relocs, we can use a plain
      reference to find the runtime address.  Without that, we have to rely
      on the `l_addr' value, which is not the value we want when prelinked.  */
+#if USE___THREAD
   dtv_t initdtv[3];
+#endif	/* USE___THREAD */
   ElfW(Ehdr) *ehdr
 # ifdef DONT_USE_BOOTSTRAP_MAP
     = (ElfW(Ehdr) *) &_begin;
@@ -348,6 +349,7 @@ _dl_start (void *arg)
   ElfW(Phdr) *phdr = (ElfW(Phdr) *) ((void *) ehdr + ehdr->e_phoff);
   size_t cnt = ehdr->e_phnum;	/* PT_TLS is usually the last phdr.  */
   while (cnt-- > 0)
+#if USE___THREAD
     if (phdr[cnt].p_type == PT_TLS)
       {
 	void *tlsblock;
@@ -442,11 +444,14 @@ _dl_start (void *arg)
 
 	/* So far this is module number one.  */
 	bootstrap_map.l_tls_modid = 1;
-
-	/* There can only be one PT_TLS entry.  */
-	break;
       }
+    else
 #endif	/* USE___THREAD */
+      if (phdr[cnt].p_type == PT_GNU_RELRO)
+	{
+	  bootstrap_map.l_relro_addr = phdr[cnt].p_vaddr;
+	  bootstrap_map.l_relro_size = phdr[cnt].p_memsz;
+	}
 
 #ifdef ELF_MACHINE_BEFORE_RTLD_RELOC
   ELF_MACHINE_BEFORE_RTLD_RELOC (bootstrap_map.l_info);
@@ -777,6 +782,11 @@ of this helper program; chances are you did not intend to run this program.\n\
 	    GL(dl_stack_flags) = ph->p_flags;
 	    break;
 	  }
+	else if (ph->p_type == PT_GNU_RELRO)
+	  {
+	    GL(dl_loaded)->l_relro_addr = ph->p_vaddr;
+	    GL(dl_loaded)->l_relro_size = ph->p_memsz;
+	  }
 
       if (__builtin_expect (mode, normal) == verify)
 	{
@@ -1598,6 +1608,35 @@ cannot allocate TLS data structures for initial thread");
 	_dl_printf ("\nprelink checking: %s\n", prelinked ? "ok" : "failed");
     }
 
+
+  /* Initialize _r_debug.  */
+  struct r_debug *r = _dl_debug_initialize (GL(dl_rtld_map).l_addr);
+  {
+    struct link_map *l;
+
+    l = GL(dl_loaded);
+
+#ifdef ELF_MACHINE_DEBUG_SETUP
+
+    /* Some machines (e.g. MIPS) don't use DT_DEBUG in this way.  */
+
+    ELF_MACHINE_DEBUG_SETUP (l, r);
+    ELF_MACHINE_DEBUG_SETUP (&GL(dl_rtld_map), r);
+
+#else
+
+    if (l->l_info[DT_DEBUG] != NULL)
+      /* There is a DT_DEBUG entry in the dynamic section.  Fill it in
+	 with the run-time address of the r_debug structure  */
+      l->l_info[DT_DEBUG]->d_un.d_ptr = (ElfW(Addr)) r;
+
+    /* Fill in the pointer in the dynamic linker's own dynamic section, in
+       case you run gdb on the dynamic linker directly.  */
+    if (GL(dl_rtld_map).l_info[DT_DEBUG] != NULL)
+      GL(dl_rtld_map).l_info[DT_DEBUG]->d_un.d_ptr = (ElfW(Addr)) r;
+#endif
+  }
+
   if (prelinked)
     {
       struct link_map *l;
@@ -1738,38 +1777,9 @@ cannot allocate TLS data structures for initial thread");
 #endif
     NONTLS_INIT_TP;
 
-  {
-    /* Initialize _r_debug.  */
-    struct r_debug *r = _dl_debug_initialize (GL(dl_rtld_map).l_addr);
-    struct link_map *l;
-
-    l = GL(dl_loaded);
-
-#ifdef ELF_MACHINE_DEBUG_SETUP
-
-    /* Some machines (e.g. MIPS) don't use DT_DEBUG in this way.  */
-
-    ELF_MACHINE_DEBUG_SETUP (l, r);
-    ELF_MACHINE_DEBUG_SETUP (&GL(dl_rtld_map), r);
-
-#else
-
-    if (l->l_info[DT_DEBUG] != NULL)
-      /* There is a DT_DEBUG entry in the dynamic section.  Fill it in
-	 with the run-time address of the r_debug structure  */
-      l->l_info[DT_DEBUG]->d_un.d_ptr = (ElfW(Addr)) r;
-
-    /* Fill in the pointer in the dynamic linker's own dynamic section, in
-       case you run gdb on the dynamic linker directly.  */
-    if (GL(dl_rtld_map).l_info[DT_DEBUG] != NULL)
-      GL(dl_rtld_map).l_info[DT_DEBUG]->d_un.d_ptr = (ElfW(Addr)) r;
-
-#endif
-
-    /* Notify the debugger that all objects are now mapped in.  */
-    r->r_state = RT_ADD;
-    INTUSE(_dl_debug_state) ();
-  }
+  /* Notify the debugger that all objects are now mapped in.  */
+  r->r_state = RT_ADD;
+  INTUSE(_dl_debug_state) ();
 
 #ifndef MAP_COPY
   /* We must munmap() the cache file.  */