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GNU C Library master sources branch hjl/cet/setjmp created. glibc-2.26.9000-864-g9f2e029
- From: hjl at sourceware dot org
- To: glibc-cvs at sourceware dot org
- Date: 29 Nov 2017 20:16:09 -0000
- Subject: GNU C Library master sources branch hjl/cet/setjmp created. glibc-2.26.9000-864-g9f2e029
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The branch, hjl/cet/setjmp has been created
at 9f2e0295b9257efd6d31139e25add937ea32fb9c (commit)
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http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=9f2e0295b9257efd6d31139e25add937ea32fb9c
commit 9f2e0295b9257efd6d31139e25add937ea32fb9c
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Sat Jun 10 17:23:06 2017 -0700
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 with a
space to store shadow stack pointer. It 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 its 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/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.
diff --git a/debug/longjmp_chk.c b/debug/longjmp_chk.c
index 1cea6c0..61be0da 100644
--- a/debug/longjmp_chk.c
+++ b/debug/longjmp_chk.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
diff --git a/setjmp/longjmp.c b/setjmp/longjmp.c
index 2453c2c..e144a87 100644
--- a/setjmp/longjmp.c
+++ b/setjmp/longjmp.c
@@ -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. */
diff --git a/setjmp/sigjmp.c b/setjmp/sigjmp.c
index 30839ae..32b727f 100644
--- a/setjmp/sigjmp.c
+++ b/setjmp/sigjmp.c
@@ -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;
}
diff --git a/debug/longjmp_chk.c b/sysdeps/generic/setjmpP.h
similarity index 81%
copy from debug/longjmp_chk.c
copy to sysdeps/generic/setjmpP.h
index 1cea6c0..a878ce6 100644
--- a/debug/longjmp_chk.c
+++ b/sysdeps/generic/setjmpP.h
@@ -1,4 +1,5 @@
-/* Copyright (C) 2009-2017 Free Software Foundation, Inc.
+/* 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
@@ -15,9 +16,9 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
-#include <setjmp.h>
+#ifndef _SETJMPP_H
+#define _SETJMPP_H 1
-#define __longjmp ____longjmp_chk
-#define __libc_siglongjmp __longjmp_chk
+#include <setjmp.h>
-#include <setjmp/longjmp.c>
+#endif /* setjmpP.h */
diff --git a/sysdeps/unix/sysv/linux/x86/Makefile b/sysdeps/unix/sysv/linux/x86/Makefile
index c069570..111ff9f 100644
--- a/sysdeps/unix/sysv/linux/x86/Makefile
+++ b/sysdeps/unix/sysv/linux/x86/Makefile
@@ -19,3 +19,7 @@ endif
ifeq ($(subdir),elf)
sysdep_routines += dl-vdso
endif
+
+ifeq ($(subdir),setjmp)
+tests += tst-saved_mask-1
+endif
diff --git a/sysdeps/unix/sysv/linux/x86/setjmpP.h b/sysdeps/unix/sysv/linux/x86/setjmpP.h
new file mode 100644
index 0000000..69a46d0
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86/setjmpP.h
@@ -0,0 +1,67 @@
+/* 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 <bits/types/__sigset_t.h>
+
+/* The biggest signal number + 1. As of kernel 4.14, x86 _NSIG is 64.
+ Define it to 513 to leave some rooms for future use. */
+#define _JUMP_BUF_SIGSET_NSIG 513
+/* 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;
+ /* Used for shadow stack pointer. */
+ unsigned long int __shadow_stack_pointer;
+ } __saved;
+ } __jmpbuf_arch_t;
+
+#undef __sigset_t
+#define __sigset_t __jmpbuf_arch_t
+#include <setjmp.h>
+#undef __saved_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");
+
+#endif /* setjmpP.h */
diff --git a/sysdeps/unix/sysv/linux/x86/tst-saved_mask-1.c b/sysdeps/unix/sysv/linux/x86/tst-saved_mask-1.c
new file mode 100644
index 0000000..f383408
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86/tst-saved_mask-1.c
@@ -0,0 +1,55 @@
+/* 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 <string.h>
+#include <errno.h>
+#include <setjmpP.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>
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