[v2,02/02] : Support for PIC modules

The patchset extends the prior PIE kernel patch (by Thomas Garnier) to also
support position-independent modules that can be placed anywhere in the
48/64-bit address space (for better KASLR). The patch extends PIE v6.

The second part implements support for position-independent modules.

Signed-off-by: Ruslan Nikolaev <rnikola@vt.edu>
Signed-off-by: Hassan Nadeem <hnadeem@vt.edu>
---
  Makefile                              |    8
  arch/x86/Kconfig                      |   12 +
  arch/x86/Makefile                     |   11 +
  arch/x86/include/asm/alternative.h    |    6
  arch/x86/include/asm/arch_hweight.h   |    5
  arch/x86/include/asm/elf.h            |    3
  arch/x86/include/asm/jump_label.h     |    4
  arch/x86/include/asm/kvm_host.h       |   15 +
  arch/x86/include/asm/module.h         |   26 ++-
  arch/x86/include/asm/paravirt.h       |    2
  arch/x86/include/asm/paravirt_types.h |    9 -
  arch/x86/include/asm/percpu.h         |    8
  arch/x86/include/asm/uaccess.h        |   60 ++++++-
  arch/x86/include/asm/xen/hypercall.h  |   20 ++
  arch/x86/kernel/Makefile              |    3
  arch/x86/kernel/alternative.c         |   24 ++
  arch/x86/kernel/ftrace.c              |   14 -
  arch/x86/kernel/module-plt-stub.S     |   23 ++
  arch/x86/kernel/module.c              |  286 
++++++++++++++++++++++++++++++----
  arch/x86/kernel/module.lds            |    1
  arch/x86/kvm/emulate.c                |    1
  arch/x86/kvm/vmx/vmenter.S            |   15 +
  arch/x86/module-lib/Makefile          |    3
  arch/x86/module-lib/retpoline.S       |   47 +++++
  arch/x86/tools/relocs.c               |    4
  arch/x86/xen/xen-head.S               |    2
  scripts/Makefile.modpost              |    2
  scripts/recordmcount.c                |    3
  tools/objtool/check.c                 |   40 +++-
  29 files changed, 570 insertions(+), 87 deletions(-)


@@ -581,7 +583,7 @@ static int add_call_destinations(struct
  	struct rela *rela;

  	for_each_insn(file, insn) {
-		if (insn->type != INSN_CALL)
+		if (insn->type != INSN_CALL && insn->type != INSN_CALL_DYNAMIC)
  			continue;

  		rela = find_rela_by_dest_range(insn->sec, insn->offset,
@@ -590,8 +592,8 @@ static int add_call_destinations(struct
  			dest_off = insn->offset + insn->len + insn->immediate;
  			insn->call_dest = find_symbol_by_offset(insn->sec,
  								dest_off);
-
-			if (!insn->call_dest && !insn->ignore) {
+			if (!insn->call_dest && !insn->ignore &&
+			    insn->type != INSN_CALL_DYNAMIC) {
  				WARN_FUNC("unsupported intra-function call",
  					  insn->sec, insn->offset);
  				if (retpoline)
@@ -602,8 +604,9 @@ static int add_call_destinations(struct
  		} else if (rela->sym->type == STT_SECTION) {
  			insn->call_dest = find_symbol_by_offset(rela->sym->sec,
  								rela->addend+4);
-			if (!insn->call_dest ||
-			    insn->call_dest->type != STT_FUNC) {
+			if ((!insn->call_dest ||
+			     insn->call_dest->type != STT_FUNC) &&
+			    insn->type != INSN_CALL_DYNAMIC) {
  				WARN_FUNC("can't find call dest symbol at %s+0x%x",
  					  insn->sec, insn->offset,
  					  rela->sym->sec->name,
@@ -836,6 +839,12 @@ static int add_switch_table(struct objto
  	struct symbol *pfunc = insn->func->pfunc;
  	unsigned int prev_offset = 0;

+	/* If PC32 relocations are used (as in PIC), the following logic
+	 * can be broken in many ways.
+	 */
+	if (file->ignore_unreachables)
+		return 0;
+
  	list_for_each_entry_from(rela, &table->rela_sec->rela_list, list) {
  		if (rela == next_table)
  			break;
@@ -1272,7 +1281,7 @@ static int decode_sections(struct objtoo

  static bool is_fentry_call(struct instruction *insn)
  {
-	if (insn->type == INSN_CALL &&
+	if (insn->call_dest &&
  	    insn->call_dest->type == STT_NOTYPE &&
  	    !strcmp(insn->call_dest->name, "__fentry__"))
  		return true;
@@ -1917,6 +1926,7 @@ static int validate_branch(struct objtoo
  			return 0;

  		case INSN_CALL:
+		case INSN_CALL_DYNAMIC:
  			if (is_fentry_call(insn))
  				break;

@@ -1926,8 +1936,6 @@ static int validate_branch(struct objtoo
  			if (ret == -1)
  				return 1;

-			/* fallthrough */
-		case INSN_CALL_DYNAMIC:
  			if (!no_fp && func && !has_valid_stack_frame(&state)) {
  				WARN_FUNC("call without frame pointer save/setup",
  					  sec, insn->offset);
@@ -1957,12 +1965,15 @@ static int validate_branch(struct objtoo
  			break;

  		case INSN_JUMP_DYNAMIC:
+			/* XXX: Does not work properly with PIC code. */
+#if 0
  			if (func && list_empty(&insn->alts) &&
  			    has_modified_stack_frame(&state)) {
  				WARN_FUNC("sibling call from callable instruction with modified 
stack frame",
  					  sec, insn->offset);
  				return 1;
  			}
+#endif

  			return 0;

@@ -2043,6 +2054,11 @@ static int validate_retpoline(struct obj
  		if (!strcmp(insn->sec->name, ".init.text") && !module)
  			continue;

+		/* ignore ftrace calls in PIC code */
+		if (!insn->call_dest ||
+		    !strcmp(insn->call_dest->name, "__fentry__"))
+			continue;
+
  		WARN_FUNC("indirect %s found in RETPOLINE build",
  			  insn->sec, insn->offset,
  			  insn->type == INSN_JUMP_DYNAMIC ? "jump" : "call");
@@ -2055,13 +2071,15 @@ static int validate_retpoline(struct obj

  static bool is_kasan_insn(struct instruction *insn)
  {
-	return (insn->type == INSN_CALL &&
+	return ((insn->type == INSN_CALL || insn->type == INSN_CALL_DYNAMIC) &&
+		insn->call_dest &&
  		!strcmp(insn->call_dest->name, "__asan_handle_no_return"));
  }

  static bool is_ubsan_insn(struct instruction *insn)
  {
-	return (insn->type == INSN_CALL &&
+	return ((insn->type == INSN_CALL || insn->type == INSN_CALL_DYNAMIC) &&
+		insn->call_dest &&
  		!strcmp(insn->call_dest->name,
  			"__ubsan_handle_builtin_unreachable"));
  }


Message ID	ce973664-08e5-20d2-46bf-1c3f58b1d5e3@yahoo.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <kernel-hardening-return-15471-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com> Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk To: kernel-hardening@lists.openwall.com Cc: thgarnie@google.com, x86@kernel.org, kstewart@linuxfoundation.org, gregkh@linuxfoundation.org, keescook@chromium.org, jpoimboe@redhat.com From: Ruslan Nikolaev <nruslan_devel@yahoo.com> Subject: [PATCH v2 02/02]: Support for PIC modules Message-ID: <ce973664-08e5-20d2-46bf-1c3f58b1d5e3@yahoo.com> Date: Wed, 20 Mar 2019 21:38:59 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit
Series	None \| expand [v2,02/02] : Support for PIC modules

[v2,02/02] : Support for PIC modules

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