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From: Yu-cheng Yu <yu-cheng.yu@intel.com>
To: x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-mm@kvack.org, linux-arch@vger.kernel.org,
	linux-api@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
	Andy Lutomirski <luto@amacapital.net>,
	Balbir Singh <bsingharora@gmail.com>,
	Borislav Petkov <bp@alien8.de>,
	Cyrill Gorcunov <gorcunov@gmail.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Eugene Syromiatnikov <esyr@redhat.com>,
	Florian Weimer <fweimer@redhat.com>,
	"H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Kees Cook <keescook@chromium.org>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Nadav Amit <nadav.amit@gmail.com>,
	Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
	Peter Zijlstra <peterz@infradead.org>,
	Randy Dunlap <rdunlap@infradead.org>,
	"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
	Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>,
	Dave Martin <Dave.Martin@arm.com>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Subject: [PATCH v8 26/27] x86/cet/shstk: Add arch_prctl functions for Shadow Stack
Date: Tue, 13 Aug 2019 13:52:24 -0700
Message-ID: <20190813205225.12032-27-yu-cheng.yu@intel.com> (raw)
In-Reply-To: <20190813205225.12032-1-yu-cheng.yu@intel.com>

arch_prctl(ARCH_X86_CET_STATUS, unsigned long *addr)
    Return CET feature status.

    The parameter 'addr' is a pointer to a user buffer.
    On returning to the caller, the kernel fills the following
    information:

    *addr = SHSTK/IBT status
    *(addr + 1) = SHSTK base address
    *(addr + 2) = SHSTK size

arch_prctl(ARCH_X86_CET_DISABLE, unsigned long features)
    Disable CET features specified in 'features'.  Return
    -EPERM if CET is locked.

arch_prctl(ARCH_X86_CET_LOCK)
    Lock in CET feature.

arch_prctl(ARCH_X86_CET_ALLOC_SHSTK, unsigned long *addr)
    Allocate a new SHSTK.

    The parameter 'addr' is a pointer to a user buffer and indicates
    the desired SHSTK size to allocate.  On returning to the caller
    the buffer contains the address of the new SHSTK.

There is no CET enabling arch_prctl function.  By design, CET is
enabled automatically if the binary and the system can support it.

The parameters passed are always unsigned 64-bit.  When an ia32
application passing pointers, it should only use the lower 32 bits.

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
 arch/x86/include/asm/cet.h        |  5 ++
 arch/x86/include/uapi/asm/prctl.h |  5 ++
 arch/x86/kernel/Makefile          |  2 +-
 arch/x86/kernel/cet.c             | 29 +++++++++++
 arch/x86/kernel/cet_prctl.c       | 85 +++++++++++++++++++++++++++++++
 arch/x86/kernel/process.c         |  4 +-
 6 files changed, 127 insertions(+), 3 deletions(-)
 create mode 100644 arch/x86/kernel/cet_prctl.c

diff --git a/arch/x86/include/asm/cet.h b/arch/x86/include/asm/cet.h
index 52c506a68848..2df357dffd24 100644
--- a/arch/x86/include/asm/cet.h
+++ b/arch/x86/include/asm/cet.h
@@ -14,19 +14,24 @@ struct sc_ext;
 struct cet_status {
 	unsigned long	shstk_base;
 	unsigned long	shstk_size;
+	unsigned int	locked:1;
 	unsigned int	shstk_enabled:1;
 };
 
 #ifdef CONFIG_X86_INTEL_CET
+int prctl_cet(int option, unsigned long arg2);
 int cet_setup_shstk(void);
 int cet_setup_thread_shstk(struct task_struct *p);
+int cet_alloc_shstk(unsigned long *arg);
 void cet_disable_shstk(void);
 void cet_disable_free_shstk(struct task_struct *p);
 int cet_restore_signal(bool ia32, struct sc_ext *sc);
 int cet_setup_signal(bool ia32, unsigned long rstor, struct sc_ext *sc);
 #else
+static inline int prctl_cet(int option, unsigned long arg2) { return -EINVAL; }
 static inline int cet_setup_shstk(void) { return -EINVAL; }
 static inline int cet_setup_thread_shstk(struct task_struct *p) { return 0; }
+static inline int cet_alloc_shstk(unsigned long *arg) { return -EINVAL; }
 static inline void cet_disable_shstk(void) {}
 static inline void cet_disable_free_shstk(struct task_struct *p) {}
 static inline int cet_restore_signal(bool ia32, struct sc_ext *sc) { return -EINVAL; }
diff --git a/arch/x86/include/uapi/asm/prctl.h b/arch/x86/include/uapi/asm/prctl.h
index 5a6aac9fa41f..d962f0ec9ccf 100644
--- a/arch/x86/include/uapi/asm/prctl.h
+++ b/arch/x86/include/uapi/asm/prctl.h
@@ -14,4 +14,9 @@
 #define ARCH_MAP_VDSO_32	0x2002
 #define ARCH_MAP_VDSO_64	0x2003
 
+#define ARCH_X86_CET_STATUS		0x3001
+#define ARCH_X86_CET_DISABLE		0x3002
+#define ARCH_X86_CET_LOCK		0x3003
+#define ARCH_X86_CET_ALLOC_SHSTK	0x3004
+
 #endif /* _ASM_X86_PRCTL_H */
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index c7d918a87cac..311829335521 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -140,7 +140,7 @@ obj-$(CONFIG_UNWINDER_ORC)		+= unwind_orc.o
 obj-$(CONFIG_UNWINDER_FRAME_POINTER)	+= unwind_frame.o
 obj-$(CONFIG_UNWINDER_GUESS)		+= unwind_guess.o
 
-obj-$(CONFIG_X86_INTEL_CET)		+= cet.o
+obj-$(CONFIG_X86_INTEL_CET)		+= cet.o cet_prctl.o
 
 ###
 # 64 bit specific files
diff --git a/arch/x86/kernel/cet.c b/arch/x86/kernel/cet.c
index e876150178ca..e4e20d6ab07b 100644
--- a/arch/x86/kernel/cet.c
+++ b/arch/x86/kernel/cet.c
@@ -127,6 +127,35 @@ static int create_rstor_token(bool ia32, unsigned long ssp,
 	return 0;
 }
 
+int cet_alloc_shstk(unsigned long *arg)
+{
+	unsigned long len = *arg;
+	unsigned long addr;
+	unsigned long token;
+	unsigned long ssp;
+
+	addr = do_mmap_locked(NULL, 0, len, PROT_READ,
+			      MAP_ANONYMOUS | MAP_PRIVATE, VM_SHSTK, NULL);
+	if (addr >= TASK_SIZE_MAX)
+		return -ENOMEM;
+
+	/* Restore token is 8 bytes and aligned to 8 bytes */
+	ssp = addr + len;
+	token = ssp;
+
+	if (!in_ia32_syscall())
+		token |= TOKEN_MODE_64;
+	ssp -= 8;
+
+	if (write_user_shstk_64(ssp, token)) {
+		vm_munmap(addr, len);
+		return -EINVAL;
+	}
+
+	*arg = addr;
+	return 0;
+}
+
 int cet_setup_shstk(void)
 {
 	unsigned long addr, size;
diff --git a/arch/x86/kernel/cet_prctl.c b/arch/x86/kernel/cet_prctl.c
new file mode 100644
index 000000000000..9c9d4262b07e
--- /dev/null
+++ b/arch/x86/kernel/cet_prctl.c
@@ -0,0 +1,85 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include <linux/errno.h>
+#include <linux/uaccess.h>
+#include <linux/prctl.h>
+#include <linux/compat.h>
+#include <linux/mman.h>
+#include <linux/elfcore.h>
+#include <asm/processor.h>
+#include <asm/prctl.h>
+#include <asm/cet.h>
+
+/* See Documentation/x86/intel_cet.rst. */
+
+static int handle_get_status(unsigned long arg2)
+{
+	unsigned int features = 0;
+	unsigned long shstk_base, shstk_size;
+	unsigned long buf[3];
+
+	if (current->thread.cet.shstk_enabled)
+		features |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
+
+	shstk_base = current->thread.cet.shstk_base;
+	shstk_size = current->thread.cet.shstk_size;
+
+	buf[0] = (unsigned long)features;
+	buf[1] = shstk_base;
+	buf[2] = shstk_size;
+	return copy_to_user((unsigned long __user *)arg2, buf,
+			    sizeof(buf));
+}
+
+static int handle_alloc_shstk(unsigned long arg2)
+{
+	int err = 0;
+	unsigned long arg;
+	unsigned long addr = 0;
+	unsigned long size = 0;
+
+	if (get_user(arg, (unsigned long __user *)arg2))
+		return -EFAULT;
+
+	size = arg;
+	err = cet_alloc_shstk(&arg);
+	if (err)
+		return err;
+
+	addr = arg;
+	if (put_user(addr, (unsigned long __user *)arg2)) {
+		vm_munmap(addr, size);
+		return -EFAULT;
+	}
+
+	return 0;
+}
+
+int prctl_cet(int option, unsigned long arg2)
+{
+	if (!cpu_x86_cet_enabled())
+		return -EINVAL;
+
+	switch (option) {
+	case ARCH_X86_CET_STATUS:
+		return handle_get_status(arg2);
+
+	case ARCH_X86_CET_DISABLE:
+		if (current->thread.cet.locked)
+			return -EPERM;
+		if (arg2 & GNU_PROPERTY_X86_FEATURE_1_SHSTK)
+			cet_disable_free_shstk(current);
+
+		return 0;
+
+	case ARCH_X86_CET_LOCK:
+		current->thread.cet.locked = 1;
+		return 0;
+
+	case ARCH_X86_CET_ALLOC_SHSTK:
+		return handle_alloc_shstk(arg2);
+
+	default:
+		return -EINVAL;
+	}
+}
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 58b1c52b38b5..e0090f2790df 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -873,7 +873,7 @@ long do_arch_prctl_common(struct task_struct *task, int option,
 		return get_cpuid_mode();
 	case ARCH_SET_CPUID:
 		return set_cpuid_mode(task, cpuid_enabled);
+	default:
+		return prctl_cet(option, cpuid_enabled);
 	}
-
-	return -EINVAL;
 }
-- 
2.17.1



  parent reply index

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-13 20:51 [PATCH v8 00/27] Control-flow Enforcement: " Yu-cheng Yu
2019-08-13 20:51 ` [PATCH v8 01/27] Documentation/x86: Add CET description Yu-cheng Yu
2019-08-14  8:07   ` Florian Weimer
2019-08-14 15:57     ` Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 02/27] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET) Yu-cheng Yu
2019-08-21 10:20   ` Borislav Petkov
2019-08-21 14:46     ` Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 03/27] x86/fpu/xstate: Change names to separate XSAVES system and user states Yu-cheng Yu
2019-08-21 14:45   ` Borislav Petkov
2019-08-13 20:52 ` [PATCH v8 04/27] x86/fpu/xstate: Introduce XSAVES system states Yu-cheng Yu
2019-08-16 19:56   ` Thomas Gleixner
2019-08-16 19:59     ` Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 05/27] x86/fpu/xstate: Introduce CET MSR " Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 06/27] x86/cet: Add control protection exception handler Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 07/27] x86/cet/shstk: Add Kconfig option for user-mode shadow stack Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 08/27] mm: Introduce VM_SHSTK for shadow stack memory Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 09/27] mm/mmap: Prevent Shadow Stack VMA merges Yu-cheng Yu
2019-08-13 22:34   ` Dave Hansen
2019-08-14 16:20     ` Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 10/27] x86/mm: Change _PAGE_DIRTY to _PAGE_DIRTY_HW Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 11/27] x86/mm: Introduce _PAGE_DIRTY_SW Yu-cheng Yu
2019-08-13 23:02   ` Dave Hansen
2019-08-13 23:49     ` Andy Lutomirski
2019-08-14 16:42     ` Yu-cheng Yu
2019-08-14 16:58       ` Dave Hansen
2019-08-23 14:02   ` Peter Zijlstra
2019-08-27 22:37     ` Yu-cheng Yu
2019-08-28  7:03       ` Peter Zijlstra
2019-08-28 14:57         ` Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 12/27] drm/i915/gvt: Update _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 13/27] x86/mm: Modify ptep_set_wrprotect and pmdp_set_wrprotect for _PAGE_DIRTY_SW Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 14/27] x86/mm: Shadow stack page fault error checking Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 15/27] mm: Handle shadow stack page fault Yu-cheng Yu
2019-08-13 22:55   ` Andy Lutomirski
2019-08-14 16:27     ` Yu-cheng Yu
2019-08-14 16:48       ` Dave Hansen
2019-08-14 17:00         ` Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 16/27] mm: Handle THP/HugeTLB " Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 17/27] mm: Update can_follow_write_pte/pmd for shadow stack Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 18/27] mm: Introduce do_mmap_locked() Yu-cheng Yu
2019-08-20  1:02   ` Sean Christopherson
2019-08-20 16:08     ` Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 19/27] x86/cet/shstk: User-mode shadow stack support Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 20/27] x86/cet/shstk: Introduce WRUSS instruction Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 21/27] x86/cet/shstk: Handle signals for shadow stack Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 22/27] binfmt_elf: Extract .note.gnu.property from an ELF file Yu-cheng Yu
2019-08-16 13:55   ` Dave Martin
2019-08-20 10:02   ` Dave Martin
2019-08-13 20:52 ` [PATCH v8 23/27] x86/cet/shstk: ELF header parsing of Shadow Stack Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 24/27] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2019-08-13 20:52 ` [PATCH v8 25/27] mm/mmap: Add Shadow stack pages to memory accounting Yu-cheng Yu
2019-08-13 20:52 ` Yu-cheng Yu [this message]
2019-08-13 20:52 ` [PATCH v8 27/27] x86/cet/shstk: Add Shadow Stack instructions to opcode map Yu-cheng Yu
2019-11-08 13:27   ` Adrian Hunter
2019-11-08 18:09     ` Yu-cheng Yu

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