On Tue, Nov 21, 2017 at 2:22 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Wed, Nov 15, 2017 at 5:20 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> On Wed, Nov 15, 2017 at 3:10 AM, Florian Weimer <fweimer@redhat.com> wrote:
>>> On 11/14/2017 02:10 PM, H.J. Lu wrote:
>>>>
>>>> +static int
>>>> +do_test (void)
>>>> +{
>>>> + sigjmp_buf sj;
>>>> + struct support_next_to_fault sigset_t_buf
>>>> + = support_next_to_fault_allocate (SIZEOF_SIGSET_T);
>>>> + sigset_t *m_p = (sigset_t *) sigset_t_buf.buffer;
>>>> + sigset_t m;
>>>> +
>>>> + sigemptyset (&m);
>>>> + memcpy (m_p, &m, SIZEOF_SIGSET_T);
>>>> + sigprocmask (SIG_SETMASK, m_p, NULL);
>>>> + memcpy (&m, m_p, SIZEOF_SIGSET_T);
>>>> + if (sigsetjmp (sj, 0) == 0)
>>>> + {
>>>> + sigaddset (&m, SIGUSR1);
>>>> + memcpy (m_p, &m, SIZEOF_SIGSET_T);
>>>> + sigprocmask (SIG_SETMASK, m_p, NULL);
>>>> + memcpy (&m, m_p, SIZEOF_SIGSET_T);
>>>> + siglongjmp (sj, 1);
>>>> + return EXIT_FAILURE;
>>>> + }
>>>> + sigprocmask (SIG_SETMASK, NULL, m_p);
>>>> + memcpy (&m, m_p, SIZEOF_SIGSET_T);
>>>> + return sigismember (&m, SIGUSR1) ? EXIT_SUCCESS : EXIT_FAILURE;
>>>> +}
>>>
>>>
>>> Sorry, I don't understand anymore what this test is supposed to test and
>>> how.
>>
>> This tests the reduced __jmp_buf_sigset_t used by __saved_mask is
>> bigger than sigset expected by kernel.
>>
>>> To be honest, I don't like how you inject the internal definition of
>>> jmp_buf. Is this the way we do it for the nptl types?
>>
>> I only need to make some room in
>>
>> /* Calling environment, plus possibly a saved signal mask. */
>> struct __jmp_buf_tag
>> {
>> /* NOTE: The machine-dependent definitions of `__sigsetjmp'
>> assume that a `jmp_buf' begins with a `__jmp_buf' and that
>> `__mask_was_saved' follows it. Do not move these members
>> or add others before it. */
>> __jmp_buf __jmpbuf; /* Calling environment. */
>> int __mask_was_saved; /* Saved the signal mask? */
>> __sigset_t __saved_mask; /* Saved signal mask. */
>> };
>>
>> for target specific purpose. I changed it to
>>
>> struct __jmp_buf_tag
>> {
>> /* NOTE: The machine-dependent definitions of `__sigsetjmp'
>> assume that a `jmp_buf' begins with a `__jmp_buf' and that
>> `__mask_was_saved' follows it. Do not move these members
>> or add others before it. */
>> __jmp_buf __jmpbuf; /* Calling environment. */
>> int __mask_was_saved; /* Saved the signal mask? */
>> union
>> {
>> __sigset_t __saved_mask_compat;
>> struct
>> {
>> __jmp_buf_sigset_t __saved_mask;
>> /* Paddings for architecture specific usage. */
>> unsigned long int __padding[12];
>> } __saved;
>> } __saved_mask;
>> };
>>
>> #define __saved_mask __saved_mask.__saved.__saved_mask
>>
>> I did only to __sigset_t in __jmp_buf_tag and this test verifies that the size
>> of __jmp_buf_sigset_t works with sigprocmask.
>>
>> Are you suggesting we make some room in __sigset_t directly? This will
>> require very extensive changes. If not, what do you exactly suggest?
>>
>>> I think you should check _JUMP_BUF_SIGSET_NSIG against a kernel constant
>>> (_NSIGS?) somewhere.
>>
>> There is a _Static_assert in include/setjmp.h. But it isn't triggered. This
>> updated patch moves it to sysdeps/unix/sysv/linux/__saved_mask.h. Now
>> I got
>>
>> ../sysdeps/unix/sysv/linux/__saved_mask.h:32:1: error: static
>> assertion failed: "size of ___saved_mask < size of
>> __sigprocmask_sigset_t"
>> _Static_assert (sizeof (___saved_mask) >= sizeof (__sigprocmask_sigset_t),
>>
>> if __jmp_buf_sigset_t is too small.
>>
>> --
>> H.J.
>
> Any comments, suggestions or objections? The patch is at
>
> https://sourceware.org/ml/libc-alpha/2017-11/msg00510.html
>
This is the updated patch. It limited the changes to Linux/x86.
Any comments?
From 71ac6d741e74e8be54fdc74132bce3def8d90bea Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Sat, 10 Jun 2017 17:23:06 -0700
Subject: [PATCH] x86: Add paddings in jmpbuf for shadow stack pointer
To support Shadow Stack (SHSTK) in Intel Control-flow Enforcement
Technology (CET) in setjmp/longjmp, we need to save shadow stack
pointer in jmp_buf. The __saved_mask field in jmp_buf has type
of __sigset_t. On Linux, __sigset_t is defined as
#define _SIGSET_NWORDS (1024 / (8 * sizeof (unsigned long int)))
typedef struct
{
unsigned long int __val[_SIGSET_NWORDS];
} __sigset_t;
which is much bigger than expected by the __sigprocmask system call,
which has
typedef struct {
unsigned long sig[_NSIG_WORDS];
} sigset_t;
For Linux/x86, we can shrink __sigset_t used by __saved_mask in jmp_buf
to add paddings for shadow stack pointer. As long as the new __sigset_t
is not smaller than sigset_t expected by the __sigprocmask system call,
it should work correctly. This patch adds an internal header file,
<setjmpP.h>, to define __jmp_buf_sigset_t for __saved_mask in jmp_buf
for Linux/x86 and verifies __jmp_buf_sigset_t has the suitable size for
the __sigprocmask system call. A run-time test, tst-saved_mask-1.c, is
added to verify that size of __jmp_buf_sigset_t is sufficient. If size
is too small, the test fails with
rt_sigprocmask(SIG_SETMASK, strace: umoven: short read (4 < 8) @0x7fa8aa28effc
0x7fa8aa28effc, NULL, 8) = -1 EFAULT (Bad address)
rt_sigprocmask(SIG_SETMASK, strace: umoven: short read (4 < 8) @0x7fa8aa28effc
0x7fa8aa28effc, NULL, 8) = -1 EFAULT (Bad address)
rt_sigprocmask(SIG_SETMASK, NULL, 0x7fa8aa28effc, 8) = -1 EFAULT (Bad address)
exit_group(1) = ?
Tested with build-many-glibcs.py.
* debug/longjmp_chk.c: Include <setjmpP.h> instead of
<setjmp.h>.
* setjmp/longjmp.c: Include <setjmpP.h> instead of <setjmp.h>.
(__libc_siglongjmp): Cast &env[0].__saved_mask to "sigset_t *".
* setjmp/sigjmp.c: Include <setjmpP.h> instead of <setjmp.h>.
(__sigjmp_save): Cast &env[0].__saved_mask to "sigset_t *".
* sysdeps/generic/setjmpP.h: New file.
* sysdeps/unix/sysv/linux/x86/__jmpbuf_arch_t.h: Likewise.
* sysdeps/unix/sysv/linux/x86/__saved_mask.h: Likewise.
* sysdeps/unix/sysv/linux/x86/setjmpP.h: Likewise.
* sysdeps/unix/sysv/linux/x86/tst-saved_mask-1.c: Likewise.
* sysdeps/unix/sysv/linux/x86/Makefile (tests): Add
tst-saved_mask-1.
---
debug/longjmp_chk.c | 2 +-
setjmp/longjmp.c | 5 ++-
setjmp/sigjmp.c | 4 +-
sysdeps/generic/setjmpP.h | 24 +++++++++++
sysdeps/unix/sysv/linux/x86/Makefile | 4 ++
sysdeps/unix/sysv/linux/x86/__jmpbuf_arch_t.h | 43 ++++++++++++++++++++
sysdeps/unix/sysv/linux/x86/__saved_mask.h | 34 ++++++++++++++++
sysdeps/unix/sysv/linux/x86/setjmpP.h | 28 +++++++++++++
sysdeps/unix/sysv/linux/x86/tst-saved_mask-1.c | 56 ++++++++++++++++++++++++++
9 files changed, 195 insertions(+), 5 deletions(-)
create mode 100644 sysdeps/generic/setjmpP.h
create mode 100644 sysdeps/unix/sysv/linux/x86/__jmpbuf_arch_t.h
create mode 100644 sysdeps/unix/sysv/linux/x86/__saved_mask.h
create mode 100644 sysdeps/unix/sysv/linux/x86/setjmpP.h
create mode 100644 sysdeps/unix/sysv/linux/x86/tst-saved_mask-1.c
@@ -15,7 +15,7 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
-#include <setjmp.h>
+#include <setjmpP.h>
#define __longjmp ____longjmp_chk
#define __libc_siglongjmp __longjmp_chk
@@ -16,7 +16,7 @@
<http://www.gnu.org/licenses/>. */
#include <stddef.h>
-#include <setjmp.h>
+#include <setjmpP.h>
#include <signal.h>
@@ -31,7 +31,8 @@ __libc_siglongjmp (sigjmp_buf env, int val)
if (env[0].__mask_was_saved)
/* Restore the saved signal mask. */
- (void) __sigprocmask (SIG_SETMASK, &env[0].__saved_mask,
+ (void) __sigprocmask (SIG_SETMASK,
+ (sigset_t *) &env[0].__saved_mask,
(sigset_t *) NULL);
/* Call the machine-dependent function to restore machine state. */
@@ -16,7 +16,7 @@
<http://www.gnu.org/licenses/>. */
#include <stddef.h>
-#include <setjmp.h>
+#include <setjmpP.h>
#include <signal.h>
/* This function is called by the `sigsetjmp' macro
@@ -28,7 +28,7 @@ __sigjmp_save (sigjmp_buf env, int savemask)
{
env[0].__mask_was_saved = (savemask &&
__sigprocmask (SIG_BLOCK, (sigset_t *) NULL,
- &env[0].__saved_mask) == 0);
+ (sigset_t *) &env[0].__saved_mask) == 0);
return 0;
}
new file mode 100644
@@ -0,0 +1,24 @@
+/* Internal header file for <setjmp.h>. Generic version.
+ Copyright (C) 2017 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
+ 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/>. */
+
+#ifndef _SETJMPP_H
+#define _SETJMPP_H 1
+
+#include <setjmp.h>
+
+#endif /* setjmpP.h */
@@ -19,3 +19,7 @@ endif
ifeq ($(subdir),elf)
sysdep_routines += dl-vdso
endif
+
+ifeq ($(subdir),setjmp)
+tests += tst-saved_mask-1
+endif
new file mode 100644
@@ -0,0 +1,43 @@
+/* __jmpbuf_arch_t defition for Linux/x86.
+ Copyright (C) 2017 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
+ 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/>. */
+
+#include <bits/types/__sigset_t.h>
+
+/* The biggest signal number + 1. As of kernel 4.13, the maximum number
+ of signals is 128 on MIPS. Define it to 257 to leave some rooms for
+ the future. */
+#define _JUMP_BUF_SIGSET_NSIG 257
+/* Number of longs to hold all signals. */
+#define _JUMP_BUF_SIGSET_NWORDS \
+ ((_JUMP_BUF_SIGSET_NSIG - 1 + 7) / (8 * sizeof (unsigned long int)))
+
+typedef struct
+ {
+ unsigned long int __val[_JUMP_BUF_SIGSET_NWORDS];
+ } __jmp_buf_sigset_t;
+
+typedef union
+ {
+ __sigset_t __saved_mask_compat;
+ struct
+ {
+ __jmp_buf_sigset_t __saved_mask;
+ /* Paddings for architecture specific usage. */
+ unsigned long int __padding[12];
+ } __saved;
+ } __jmpbuf_arch_t;
new file mode 100644
@@ -0,0 +1,34 @@
+/* __saved_mask defition for Linux/x86.
+ Copyright (C) 2017 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
+ 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/>. */
+
+/* Saved signal mask. */
+#define __saved_mask __saved_mask.__saved.__saved_mask
+
+#include <signal.h>
+
+#define _SIGPROCMASK_NSIG_WORDS (_NSIG / (8 * sizeof (unsigned long int)))
+
+typedef struct
+ {
+ unsigned long int __val[_SIGPROCMASK_NSIG_WORDS];
+ } __sigprocmask_sigset_t;
+
+extern jmp_buf ___buf;
+extern __typeof (___buf[0].__saved_mask) ___saved_mask;
+_Static_assert (sizeof (___saved_mask) >= sizeof (__sigprocmask_sigset_t),
+ "size of ___saved_mask < size of __sigprocmask_sigset_t");
new file mode 100644
@@ -0,0 +1,28 @@
+/* Internal header file for <setjmp.h>. Linux/x86 version.
+ Copyright (C) 2017 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
+ 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/>. */
+
+#ifndef _SETJMPP_H
+#define _SETJMPP_H 1
+
+#include <__jmpbuf_arch_t.h>
+#undef __sigset_t
+#define __sigset_t __jmpbuf_arch_t
+#include <setjmp.h>
+#include <__saved_mask.h>
+
+#endif /* setjmpP.h */
new file mode 100644
@@ -0,0 +1,56 @@
+/* Test that sigprocmask does not read from the unused part of jmpbuf.
+ Copyright (C) 2017 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
+ 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/>. */
+
+#include <stdlib.h>
+#include <signal.h>
+#include <setjmp.h>
+#include <string.h>
+#include <errno.h>
+#include <__jmpbuf_arch_t.h>
+#include <support/next_to_fault.h>
+
+#define SIZEOF_SIGSET_T sizeof (__jmp_buf_sigset_t)
+
+static int
+do_test (void)
+{
+ sigjmp_buf sj;
+ struct support_next_to_fault sigset_t_buf
+ = support_next_to_fault_allocate (SIZEOF_SIGSET_T);
+ sigset_t *m_p = (sigset_t *) sigset_t_buf.buffer;
+ sigset_t m;
+
+ sigemptyset (&m);
+ memcpy (m_p, &m, SIZEOF_SIGSET_T);
+ sigprocmask (SIG_SETMASK, m_p, NULL);
+ memcpy (&m, m_p, SIZEOF_SIGSET_T);
+ if (sigsetjmp (sj, 0) == 0)
+ {
+ sigaddset (&m, SIGUSR1);
+ memcpy (m_p, &m, SIZEOF_SIGSET_T);
+ sigprocmask (SIG_SETMASK, m_p, NULL);
+ memcpy (&m, m_p, SIZEOF_SIGSET_T);
+ siglongjmp (sj, 1);
+ return EXIT_FAILURE;
+ }
+ sigprocmask (SIG_SETMASK, NULL, m_p);
+ memcpy (&m, m_p, SIZEOF_SIGSET_T);
+ return sigismember (&m, SIGUSR1) ? EXIT_SUCCESS : EXIT_FAILURE;
+}
+
+#include <support/test-driver.c>
--
2.14.3