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Re: [PATCH] i386: Use _dl_runtime_[resolve|profile]_shstk for SHSTK [BZ #23716]
On Fri, Sep 28, 2018 at 7:33 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Wed, Sep 26, 2018 at 10:30 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> On Wed, Sep 26, 2018 at 10:23 AM, Florian Weimer <fweimer@redhat.com> wrote:
>>> * H. J. Lu:
>>>
>>>> diff --git a/sysdeps/i386/dl-trampoline.S b/sysdeps/i386/dl-trampoline.S
>>>> index 6dc0319216..9734f9c981 100644
>>>> --- a/sysdeps/i386/dl-trampoline.S
>>>> +++ b/sysdeps/i386/dl-trampoline.S
>>>> @@ -33,6 +33,7 @@
>>>> _dl_runtime_resolve:
>>>> cfi_adjust_cfa_offset (8)
>>>> _CET_ENDBR
>>>> + hlt
>>>> pushl %eax # Preserve registers otherwise clobbered.
>>>> cfi_adjust_cfa_offset (4)
>>>> pushl %ecx
>>>
>>> That doesn't look right. 8-)
>>>
>>
>> This is the change I used to test my fix to verify that the SHSTK resolver
>> is used if SHSTK is enabled by kernel. It isn't the part of the fix.
>>
>
> We verified that the fix worked on CET simulator. If there is no objection,
> I will check it later today.
>
> Thanks.
This is the patch I am checking in now.
--
H.J.
From 99226ceb67a8d2afbcf291b5da349ee7432f10db Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Wed, 26 Sep 2018 10:09:05 -0700
Subject: [PATCH] i386: Use _dl_runtime_[resolve|profile]_shstk for SHSTK [BZ
#23716]
When elf_machine_runtime_setup is called to set up resolver, it should
use _dl_runtime_resolve_shstk or _dl_runtime_profile_shstk if SHSTK is
enabled by kernel.
Tested on i686 with and without --enable-cet as well as on CET emulator
with --enable-cet.
[BZ #23716]
* sysdeps/i386/dl-cet.c: Removed.
* sysdeps/i386/dl-machine.h (_dl_runtime_resolve_shstk): New
prototype.
(_dl_runtime_profile_shstk): Likewise.
(elf_machine_runtime_setup): Use _dl_runtime_profile_shstk or
_dl_runtime_resolve_shstk if SHSTK is enabled by kernel.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
---
sysdeps/i386/dl-cet.c | 67 ---------------------------------------
sysdeps/i386/dl-machine.h | 13 ++++++--
2 files changed, 11 insertions(+), 69 deletions(-)
delete mode 100644 sysdeps/i386/dl-cet.c
diff --git a/sysdeps/i386/dl-cet.c b/sysdeps/i386/dl-cet.c
deleted file mode 100644
index 5d9a4e8d51..0000000000
--- a/sysdeps/i386/dl-cet.c
+++ /dev/null
@@ -1,67 +0,0 @@
-/* Linux/i386 CET initializers function.
- Copyright (C) 2018 Free Software Foundation, Inc.
-
- The GNU C Library is free software; you can redistribute it and/or
- modify it under the terms of the GNU Lesser General Public
- License as published by the Free Software Foundation; either
- version 2.1 of the License, or (at your option) any later version.
-
- The GNU C Library is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public
- License along with the GNU C Library; if not, see
- <http://www.gnu.org/licenses/>. */
-
-
-#define LINKAGE static inline
-#define _dl_cet_check cet_check
-#include <sysdeps/x86/dl-cet.c>
-#undef _dl_cet_check
-
-#ifdef SHARED
-void
-_dl_cet_check (struct link_map *main_map, const char *program)
-{
- cet_check (main_map, program);
-
- if ((GL(dl_x86_feature_1)[0] & GNU_PROPERTY_X86_FEATURE_1_SHSTK))
- {
- /* Replace _dl_runtime_resolve and _dl_runtime_profile with
- _dl_runtime_resolve_shstk and _dl_runtime_profile_shstk,
- respectively if SHSTK is enabled. */
- extern void _dl_runtime_resolve (Elf32_Word) attribute_hidden;
- extern void _dl_runtime_resolve_shstk (Elf32_Word) attribute_hidden;
- extern void _dl_runtime_profile (Elf32_Word) attribute_hidden;
- extern void _dl_runtime_profile_shstk (Elf32_Word) attribute_hidden;
- unsigned int i;
- struct link_map *l;
- Elf32_Addr *got;
-
- if (main_map->l_info[DT_JMPREL])
- {
- got = (Elf32_Addr *) D_PTR (main_map, l_info[DT_PLTGOT]);
- if (got[2] == (Elf32_Addr) &_dl_runtime_resolve)
- got[2] = (Elf32_Addr) &_dl_runtime_resolve_shstk;
- else if (got[2] == (Elf32_Addr) &_dl_runtime_profile)
- got[2] = (Elf32_Addr) &_dl_runtime_profile_shstk;
- }
-
- i = main_map->l_searchlist.r_nlist;
- while (i-- > 0)
- {
- l = main_map->l_initfini[i];
- if (l->l_info[DT_JMPREL])
- {
- got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
- if (got[2] == (Elf32_Addr) &_dl_runtime_resolve)
- got[2] = (Elf32_Addr) &_dl_runtime_resolve_shstk;
- else if (got[2] == (Elf32_Addr) &_dl_runtime_profile)
- got[2] = (Elf32_Addr) &_dl_runtime_profile_shstk;
- }
- }
- }
-}
-#endif
diff --git a/sysdeps/i386/dl-machine.h b/sysdeps/i386/dl-machine.h
index 1afdcbd9ea..f6cfb90e21 100644
--- a/sysdeps/i386/dl-machine.h
+++ b/sysdeps/i386/dl-machine.h
@@ -67,6 +67,11 @@ elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
Elf32_Addr *got;
extern void _dl_runtime_resolve (Elf32_Word) attribute_hidden;
extern void _dl_runtime_profile (Elf32_Word) attribute_hidden;
+ extern void _dl_runtime_resolve_shstk (Elf32_Word) attribute_hidden;
+ extern void _dl_runtime_profile_shstk (Elf32_Word) attribute_hidden;
+ /* Check if SHSTK is enabled by kernel. */
+ bool shstk_enabled
+ = (GL(dl_x86_feature_1)[0] & GNU_PROPERTY_X86_FEATURE_1_SHSTK) != 0;
if (l->l_info[DT_JMPREL] && lazy)
{
@@ -93,7 +98,9 @@ elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
end in this function. */
if (__glibc_unlikely (profile))
{
- got[2] = (Elf32_Addr) &_dl_runtime_profile;
+ got[2] = (shstk_enabled
+ ? (Elf32_Addr) &_dl_runtime_profile_shstk
+ : (Elf32_Addr) &_dl_runtime_profile);
if (GLRO(dl_profile) != NULL
&& _dl_name_match_p (GLRO(dl_profile), l))
@@ -104,7 +111,9 @@ elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
else
/* This function will get called to fix up the GOT entry indicated by
the offset on the stack, and then jump to the resolved address. */
- got[2] = (Elf32_Addr) &_dl_runtime_resolve;
+ got[2] = (shstk_enabled
+ ? (Elf32_Addr) &_dl_runtime_resolve_shstk
+ : (Elf32_Addr) &_dl_runtime_resolve);
}
return lazy;
--
2.17.1