From: Ulrich Drepper <drepper@redhat.com>
Date: Sun, 11 Jun 2006 00:20:43 +0000 (+0000)
Subject: Implement -z execstack/noexecstack options.
X-Git-Tag: elfutils-0.121~12
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2d88028a7b30d9e9be8e5af089cd6dcc22f80ce1;p=thirdparty%2Felfutils.git

Implement -z execstack/noexecstack options.
---

diff --git a/src/ChangeLog b/src/ChangeLog
index fb4e011dc..8bfd20c4c 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,12 @@
+2006-06-10  Ulrich Drepper  <drepper@redhat.com>
+
+	* ld.c (parse_z_option): Recognize execstack and noexecstack.
+	* ld.h (struct ld_state): Add execstack field.
+	* ldgeneric.c (add_relocatable_file): Recognize .note.GNU-stack
+	sections.
+	(ld_generic_create_outfile): Fix program header creation in native
+	linker.  Add PT_GNU_STACK program header.
+
 2006-06-09  Ulrich Drepper  <drepper@redhat.com>
 
 	* i386_ld.c (elf_i386_finalize_plt): Don't change symbol table entries
diff --git a/src/ld.c b/src/ld.c
index 533865694..79efb3ac6 100644
--- a/src/ld.c
+++ b/src/ld.c
@@ -931,6 +931,10 @@ parse_z_option (const char *arg)
     ld_state.as_needed = false;
   else if (strcmp (arg, "systemlibrary") == 0)
     ld_state.is_system_library = true;
+  else if (strcmp (arg, "execstack") == 0)
+    ld_state.execstack = execstack_true;
+  else if (strcmp (arg, "noexecstack") == 0)
+    ld_state.execstack = execstack_false_force;
   else if (strcmp (arg, "allextract") != 0
 	   && strcmp (arg, "defaultextract") != 0
 	   && strcmp (arg, "weakextract") != 0
diff --git a/src/ld.h b/src/ld.h
index 6e8e7b5fa..1d9648149 100644
--- a/src/ld.h
+++ b/src/ld.h
@@ -956,6 +956,14 @@ struct ld_state
   bool default_bind_local;
   bool default_bind_global;
 
+  /* Execuatable stack selection.  */
+  enum execstack
+    {
+      execstack_false = 0, 
+      execstack_true,
+      execstack_false_force
+    } execstack;
+
   /* True if only used sections are used.  */
   bool gc_sections;
 
diff --git a/src/ldgeneric.c b/src/ldgeneric.c
index 6cad1ac7d..07cf3e192 100644
--- a/src/ldgeneric.c
+++ b/src/ldgeneric.c
@@ -1028,6 +1028,9 @@ add_relocatable_file (struct usedfiles *fileinfo, GElf_Word secttype)
   size_t nsymbols = 0;
   size_t nlocalsymbols = 0;
   bool has_merge_sections = false;
+  /* Unless we have different information we assume the code needs
+     an executable stack.  */
+  enum execstack execstack = execstack_true;
 
   /* Prerequisites.  */
   assert (fileinfo->elf != NULL);
@@ -1234,9 +1237,29 @@ add_relocatable_file (struct usedfiles *fileinfo, GElf_Word secttype)
 			  || shdr->sh_type == SHT_INIT_ARRAY
 			  || shdr->sh_type == SHT_FINI_ARRAY
 			  || shdr->sh_type == SHT_PREINIT_ARRAY))
-	add_section (fileinfo, &fileinfo->scninfo[cnt]);
+	{
+	  /* Check whether the check needs to be executable.  */
+	  if (shdr->sh_type == SHT_PROGBITS
+	      && strcmp (elf_strptr (fileinfo->elf, fileinfo->shstrndx,
+				     shdr->sh_name),
+			 ".note.GNU-stack") == 0
+	      && (shdr->sh_flags & SHF_EXECINSTR) == 0)
+	    execstack = execstack_false;
+	  printf("%s %d\n", elf_strptr (fileinfo->elf, fileinfo->shstrndx,
+					shdr->sh_name),(int)execstack);
+
+	  add_section (fileinfo, &fileinfo->scninfo[cnt]);
+	}
     }
 
+  /* Now we know more about the requirements for an executable stack
+     of the result.  */
+  if (fileinfo->file_type == relocatable_file_type
+      && execstack == execstack_true
+      && ld_state.execstack != execstack_false_force)
+    ld_state.execstack = execstack_true;
+  printf("%s: state = %d\n", fileinfo->fname,(int)ld_state.execstack);
+
   /* Handle the symbols.  Record defined and undefined symbols in the
      hash table.  In theory there can be a file without any symbol
      table.  */
@@ -5573,6 +5596,10 @@ cannot create hash table section for output file: %s"),
 
 	 XXX Determine whether the segment is non-empty.  */
       nphdr = 0;
+
+      /* We always add a PT_GNU_stack entry.  */
+      ++nphdr;
+
       segment = ld_state.output_segments;
       while (segment != NULL)
 	{
@@ -5772,7 +5799,7 @@ internal error: nobits section follows nobits section"));
       xelf_getehdr (ld_state.outelf, ehdr);
       assert (ehdr != NULL);
 
-      xelf_getphdr_ptr (ld_state.outelf, 1, phdr);
+      xelf_getphdr_ptr (ld_state.outelf, 0, phdr);
       phdr->p_type = PT_PHDR;
       phdr->p_offset = ehdr->e_phoff;
       phdr->p_vaddr = ld_state.output_segments->addr + phdr->p_offset;
@@ -5784,6 +5811,21 @@ internal error: nobits section follows nobits section"));
       (void) xelf_update_phdr (ld_state.outelf, 0, phdr);
 
 
+      /* Add the stack information.  */
+      xelf_getphdr_ptr (ld_state.outelf, nphdr, phdr);
+      phdr->p_type = PT_GNU_STACK;
+      phdr->p_offset = 0;
+      phdr->p_vaddr = 0;
+      phdr->p_paddr = 0;
+      phdr->p_filesz = 0;
+      phdr->p_memsz = 0;
+      phdr->p_flags = ld_state.execstack == execstack_true ? PF_X : 0;
+      phdr->p_align = 0;
+
+      (void) xelf_update_phdr (ld_state.outelf, nphdr, phdr);
+      ++nphdr;
+
+
       /* Adjust the addresses in the address fields of the symbol
 	 records according to the load addresses of the sections.  */
       if (ld_state.need_symtab)