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V3 [PATCH 04/12] x86/CET: Extend arch_prctl syscall for CET control
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: "Carlos O'Donell" <carlos at redhat dot com>
- Cc: Joseph Myers <joseph at codesourcery dot com>, GNU C Library <libc-alpha at sourceware dot org>
- Date: Tue, 24 Jul 2018 08:52:08 -0700
- Subject: V3 [PATCH 04/12] x86/CET: Extend arch_prctl syscall for CET control
On Tue, Jul 24, 2018 at 8:29 AM, Carlos O'Donell <carlos@redhat.com> wrote:
> On 07/24/2018 10:28 AM, Joseph Myers wrote:
>> On Tue, 24 Jul 2018, H.J. Lu wrote:
>>
>>> Note: sysdeps/unix/sysv/linux/x86/bits/prctl-internal.h should be
>>> renamed to sysdeps/unix/sysv/linux/x86/bits/prctl.h after the CET
>>> kernel interface has been committed into the public kernel.
>>
>> bits/ should not be used for any internal headers; it's purely a naming
>> convention for public headers. So there should be no
>> bits/prctl-internal.h header.
>
> OK.
>
>> I don't think there should be bits/prctl.h at all either. Not with this
>> patch (because there isn't anything for it to do), and not once the
>> interface is in the kernel (because existing practice is that we rely on
>> the include of <linux/prctl.h> from <sys/prctl.h> to provide the values to
>> users of glibc).
>
> Good point.
>
>> Rather, for the uses of these constants within glibc, to avoid relying on
>> new kernel headers, provide an x86 include/sys/prctl.h that does
>> #include_next <sys/prctl.h> and then defines these constants if not
>> already defined. And make sure that header gets a prominent comment
>> naming the upstream kernel version with the constants (once they are
>> upstream), so it's obvious at what point we can remove that header.
>
> OK, that makes sense, so a purely internal header via include/ wrapping
> with the constants there.
>
CET arch_prctl bits should be defined in <asm/prctl.h> from Linux kernel
header files. Here is the updated patch to add x86 <include/asm/prctl.h>.
OK for master?
--
H.J.
From 630bfa00750c823cd4bea26ca6e1eabfd7abba99 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Sat, 7 Jul 2018 07:33:04 -0700
Subject: [PATCH] x86/CET: Extend arch_prctl syscall for CET control
CET arch_prctl bits should be defined in <asm/prctl.h> from Linux kernel
header files. Add x86 <include/asm/prctl.h> for pre-CET kernel header
files.
Note: sysdeps/unix/sysv/linux/x86/include/asm/prctl.h should be removed
after the CET kernel interface has been committed into the public kernel.
/* CET features:
IBT: GNU_PROPERTY_X86_FEATURE_1_IBT
SHSTK: GNU_PROPERTY_X86_FEATURE_1_SHSTK
*/
/* Return CET features in unsigned long long *addr:
features: addr[0].
shadow stack base address: addr[1].
shadow stack size: addr[2].
*/
# define ARCH_CET_STATUS 0x3001
/* Disable CET features in unsigned int features. */
# define ARCH_CET_DISABLE 0x3002
/* Lock all CET features. */
# define ARCH_CET_LOCK 0x3003
/* Allocate a new shadow stack with unsigned long long *addr:
IN: requested shadow stack size: *addr.
OUT: allocated shadow stack address: *addr.
*/
# define ARCH_CET_ALLOC_SHSTK 0x3004
/* Return legacy region bitmap info in unsigned long long *addr:
address: addr[0].
size: addr[1].
*/
# define ARCH_CET_LEGACY_BITMAP 0x3005
* sysdeps/unix/sysv/linux/x86/include/asm/prctl.h: New file.
* sysdeps/unix/sysv/linux/x86/cpu-features.c: Include
<sys/prctl.h> and <asm/prctl.h>.
(get_cet_status): Call arch_prctl with ARCH_CET_STATUS.
* sysdeps/unix/sysv/linux/x86/dl-cet.h: Include <sys/prctl.h>
and <asm/prctl.h>.
(dl_cet_allocate_legacy_bitmap): Call arch_prctl with
ARCH_CET_LEGACY_BITMAP.
(dl_cet_disable_cet): Call arch_prctl with ARCH_CET_DISABLE.
(dl_cet_lock_cet): Call arch_prctl with ARCH_CET_LOCK.
* sysdeps/x86/libc-start.c: Include <startup.h>.
---
sysdeps/unix/sysv/linux/x86/cpu-features.c | 8 +++++
sysdeps/unix/sysv/linux/x86/dl-cet.h | 30 +++++++++++++----
.../unix/sysv/linux/x86/include/asm/prctl.h | 32 +++++++++++++++++++
sysdeps/x86/libc-start.c | 3 ++
4 files changed, 67 insertions(+), 6 deletions(-)
create mode 100644 sysdeps/unix/sysv/linux/x86/include/asm/prctl.h
diff --git a/sysdeps/unix/sysv/linux/x86/cpu-features.c b/sysdeps/unix/sysv/linux/x86/cpu-features.c
index 7c9df9b794..8566a265b8 100644
--- a/sysdeps/unix/sysv/linux/x86/cpu-features.c
+++ b/sysdeps/unix/sysv/linux/x86/cpu-features.c
@@ -17,9 +17,17 @@
<http://www.gnu.org/licenses/>. */
#if CET_ENABLED
+# include <sys/prctl.h>
+# include <asm/prctl.h>
+
static inline int __attribute__ ((always_inline))
get_cet_status (void)
{
+ unsigned long long cet_status[3];
+ INTERNAL_SYSCALL_DECL (err);
+ if (INTERNAL_SYSCALL (arch_prctl, err, 2, ARCH_CET_STATUS,
+ cet_status) == 0)
+ return cet_status[0];
return 0;
}
diff --git a/sysdeps/unix/sysv/linux/x86/dl-cet.h b/sysdeps/unix/sysv/linux/x86/dl-cet.h
index ae81e2f2ca..3fbcfebed5 100644
--- a/sysdeps/unix/sysv/linux/x86/dl-cet.h
+++ b/sysdeps/unix/sysv/linux/x86/dl-cet.h
@@ -15,23 +15,41 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
+#include <sys/prctl.h>
+#include <asm/prctl.h>
+
static inline int __attribute__ ((always_inline))
dl_cet_allocate_legacy_bitmap (unsigned long *legacy_bitmap)
{
- /* FIXME: Need syscall support. */
- return -1;
+ /* Allocate legacy bitmap. */
+ INTERNAL_SYSCALL_DECL (err);
+#ifdef __LP64__
+ return (int) INTERNAL_SYSCALL (arch_prctl, err, 2,
+ ARCH_CET_LEGACY_BITMAP, legacy_bitmap);
+#else
+ unsigned long long legacy_bitmap_u64[2];
+ int res = INTERNAL_SYSCALL (arch_prctl, err, 2,
+ ARCH_CET_LEGACY_BITMAP, legacy_bitmap_u64);
+ if (res == 0)
+ {
+ legacy_bitmap[0] = legacy_bitmap_u64[0];
+ legacy_bitmap[1] = legacy_bitmap_u64[1];
+ }
+ return res;
+#endif
}
static inline int __attribute__ ((always_inline))
dl_cet_disable_cet (unsigned int cet_feature)
{
- /* FIXME: Need syscall support. */
- return -1;
+ INTERNAL_SYSCALL_DECL (err);
+ return (int) INTERNAL_SYSCALL (arch_prctl, err, 2, ARCH_CET_DISABLE,
+ cet_feature);
}
static inline int __attribute__ ((always_inline))
dl_cet_lock_cet (void)
{
- /* FIXME: Need syscall support. */
- return -1;
+ INTERNAL_SYSCALL_DECL (err);
+ return (int) INTERNAL_SYSCALL (arch_prctl, err, 2, ARCH_CET_LOCK, 0);
}
diff --git a/sysdeps/unix/sysv/linux/x86/include/asm/prctl.h b/sysdeps/unix/sysv/linux/x86/include/asm/prctl.h
new file mode 100644
index 0000000000..c92c4104af
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86/include/asm/prctl.h
@@ -0,0 +1,32 @@
+/* FIXME: This file should be removed after the CET kernel interface
+ has been committed into the public kernel. All CET arch_prctl bits
+ should come from the kernel <asm/prctl.h>. */
+
+#include_next <asm/prctl.h>
+
+#ifndef ARCH_CET_STATUS
+/* CET features:
+ IBT: GNU_PROPERTY_X86_FEATURE_1_IBT
+ SHSTK: GNU_PROPERTY_X86_FEATURE_1_SHSTK
+ */
+/* Return CET features in unsigned long long *addr:
+ features: addr[0].
+ shadow stack base address: addr[1].
+ shadow stack size: addr[2].
+ */
+# define ARCH_CET_STATUS 0x3001
+/* Disable CET features in unsigned int features. */
+# define ARCH_CET_DISABLE 0x3002
+/* Lock all CET features. */
+# define ARCH_CET_LOCK 0x3003
+/* Allocate a new shadow stack with unsigned long long *addr:
+ IN: requested shadow stack size: *addr.
+ OUT: allocated shadow stack address: *addr.
+ */
+# define ARCH_CET_ALLOC_SHSTK 0x3004
+/* Return legacy region bitmap info in unsigned long long *addr:
+ address: addr[0].
+ size: addr[1].
+ */
+# define ARCH_CET_LEGACY_BITMAP 0x3005
+#endif /* ARCH_CET_STATUS */
diff --git a/sysdeps/x86/libc-start.c b/sysdeps/x86/libc-start.c
index 43aba9d061..eb5335c154 100644
--- a/sysdeps/x86/libc-start.c
+++ b/sysdeps/x86/libc-start.c
@@ -16,6 +16,9 @@
<http://www.gnu.org/licenses/>. */
#ifndef SHARED
+/* Define I386_USE_SYSENTER to support syscall during startup in static
+ PIE. */
+# include <startup.h>
# include <ldsodefs.h>
# include <cpu-features.h>
# include <cpu-features.c>
--
2.17.1