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@kernel.org>,
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>,
Weijiang Yang <weijiang.yang@intel.com>,
Pengfei Xu <pengfei.xu@intel.com>,
Haitao Huang <haitao.huang@intel.com>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Subject: [PATCH v25 27/30] x86/cet/shstk: Add arch_prctl functions for shadow stack
Date: Thu, 15 Apr 2021 15:14:16 -0700 [thread overview]
Message-ID: <20210415221419.31835-28-yu-cheng.yu@intel.com> (raw)
In-Reply-To: <20210415221419.31835-1-yu-cheng.yu@intel.com>
arch_prctl(ARCH_X86_CET_STATUS, u64 *args)
Get CET feature status.
The parameter 'args' is a pointer to a user buffer. The kernel returns
the following information:
*args = shadow stack/IBT status
*(args + 1) = shadow stack base address
*(args + 2) = shadow stack size
32-bit binaries use the same interface, but only lower 32-bits of each
item.
arch_prctl(ARCH_X86_CET_DISABLE, unsigned int features)
Disable CET features specified in 'features'. Return -EPERM if CET is
locked.
arch_prctl(ARCH_X86_CET_LOCK)
Lock in CET features.
Also change do_arch_prctl_common()'s parameter 'cpuid_enabled' to
'arg2', as it is now also passed to prctl_cet().
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
v25:
- Change CONFIG_X86_CET to CONFIG_X86_SHADOW_STACK.
- Change X86_FEATURE_CET to X86_FEATURE_SHSTK.
v24:
- Update #ifdef placement relating to shadow stack and ibt split.
- Update function names.
arch/x86/include/asm/cet.h | 7 ++++
arch/x86/include/uapi/asm/prctl.h | 4 +++
arch/x86/kernel/Makefile | 2 +-
arch/x86/kernel/cet_prctl.c | 60 +++++++++++++++++++++++++++++++
arch/x86/kernel/process.c | 6 ++--
5 files changed, 75 insertions(+), 4 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 5e66919bd2fe..662335ceb57f 100644
--- a/arch/x86/include/asm/cet.h
+++ b/arch/x86/include/asm/cet.h
@@ -14,6 +14,7 @@ struct sc_ext;
struct cet_status {
unsigned long shstk_base;
unsigned long shstk_size;
+ unsigned int locked:1;
};
#ifdef CONFIG_X86_SHADOW_STACK
@@ -40,6 +41,12 @@ static inline int shstk_check_rstor_token(bool ia32, unsigned long token_addr,
unsigned long *new_ssp) { return 0; }
#endif
+#ifdef CONFIG_X86_SHADOW_STACK
+int prctl_cet(int option, u64 arg2);
+#else
+static inline int prctl_cet(int option, u64 arg2) { return -EINVAL; }
+#endif
+
#endif /* __ASSEMBLY__ */
#endif /* _ASM_X86_CET_H */
diff --git a/arch/x86/include/uapi/asm/prctl.h b/arch/x86/include/uapi/asm/prctl.h
index 5a6aac9fa41f..9245bf629120 100644
--- a/arch/x86/include/uapi/asm/prctl.h
+++ b/arch/x86/include/uapi/asm/prctl.h
@@ -14,4 +14,8 @@
#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
+
#endif /* _ASM_X86_PRCTL_H */
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 0f99b093f350..eb13d578ad36 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -150,7 +150,7 @@ obj-$(CONFIG_UNWINDER_FRAME_POINTER) += unwind_frame.o
obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
obj-$(CONFIG_AMD_MEM_ENCRYPT) += sev-es.o
-obj-$(CONFIG_X86_SHADOW_STACK) += shstk.o
+obj-$(CONFIG_X86_SHADOW_STACK) += shstk.o cet_prctl.o
###
# 64 bit specific files
diff --git a/arch/x86/kernel/cet_prctl.c b/arch/x86/kernel/cet_prctl.c
new file mode 100644
index 000000000000..3bb9f32ca70d
--- /dev/null
+++ b/arch/x86/kernel/cet_prctl.c
@@ -0,0 +1,60 @@
+// 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 <linux/processor.h>
+#include <asm/prctl.h>
+#include <asm/cet.h>
+
+/* See Documentation/x86/intel_cet.rst. */
+
+static int cet_copy_status_to_user(struct cet_status *cet, u64 __user *ubuf)
+{
+ u64 buf[3] = {};
+
+ if (cet->shstk_size) {
+ buf[0] |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
+ buf[1] = cet->shstk_base;
+ buf[2] = cet->shstk_size;
+ }
+
+ return copy_to_user(ubuf, buf, sizeof(buf));
+}
+
+int prctl_cet(int option, u64 arg2)
+{
+ struct cet_status *cet;
+
+ if (!cpu_feature_enabled(X86_FEATURE_SHSTK))
+ return -ENOTSUPP;
+
+ cet = ¤t->thread.cet;
+
+ if (option == ARCH_X86_CET_STATUS)
+ return cet_copy_status_to_user(cet, (u64 __user *)arg2);
+
+ switch (option) {
+ case ARCH_X86_CET_DISABLE:
+ if (cet->locked)
+ return -EPERM;
+
+ if (arg2 & ~GNU_PROPERTY_X86_FEATURE_1_VALID)
+ return -EINVAL;
+ if (arg2 & GNU_PROPERTY_X86_FEATURE_1_SHSTK)
+ shstk_disable();
+ return 0;
+
+ case ARCH_X86_CET_LOCK:
+ if (arg2)
+ return -EINVAL;
+ cet->locked = 1;
+ return 0;
+
+ default:
+ return -ENOSYS;
+ }
+}
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index fa01e8679d01..315668a334fd 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -980,14 +980,14 @@ unsigned long get_wchan(struct task_struct *p)
}
long do_arch_prctl_common(struct task_struct *task, int option,
- unsigned long cpuid_enabled)
+ unsigned long arg2)
{
switch (option) {
case ARCH_GET_CPUID:
return get_cpuid_mode();
case ARCH_SET_CPUID:
- return set_cpuid_mode(task, cpuid_enabled);
+ return set_cpuid_mode(task, arg2);
}
- return -EINVAL;
+ return prctl_cet(option, arg2);
}
--
2.21.0
next prev parent reply other threads:[~2021-04-15 22:18 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-15 22:13 [PATCH v25 00/30] Control-flow Enforcement: Shadow Stack Yu-cheng Yu
2021-04-15 22:13 ` [PATCH v25 01/30] Documentation/x86: Add CET description Yu-cheng Yu
2021-04-15 22:13 ` [PATCH v25 02/30] x86/cet/shstk: Add Kconfig option for Shadow Stack Yu-cheng Yu
2021-04-15 22:13 ` [PATCH v25 03/30] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET) Yu-cheng Yu
2021-04-15 22:13 ` [PATCH v25 04/30] x86/cpufeatures: Introduce CPU setup and option parsing for CET Yu-cheng Yu
2021-04-15 22:13 ` [PATCH v25 05/30] x86/fpu/xstate: Introduce CET MSR and XSAVES supervisor states Yu-cheng Yu
2021-04-15 22:13 ` [PATCH v25 06/30] x86/cet: Add control-protection fault handler Yu-cheng Yu
2021-04-15 22:13 ` [PATCH v25 07/30] x86/mm: Remove _PAGE_DIRTY from kernel RO pages Yu-cheng Yu
2021-04-15 22:13 ` [PATCH v25 08/30] x86/mm: Move pmd_write(), pud_write() up in the file Yu-cheng Yu
2021-04-15 22:13 ` [PATCH v25 09/30] x86/mm: Introduce _PAGE_COW Yu-cheng Yu
2021-04-15 22:13 ` [PATCH v25 10/30] drm/i915/gvt: Change _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2021-04-15 22:14 ` [PATCH v25 11/30] x86/mm: Update pte_modify for _PAGE_COW Yu-cheng Yu
2021-04-15 22:14 ` [PATCH v25 12/30] x86/mm: Update ptep_set_wrprotect() and pmdp_set_wrprotect() for transition from _PAGE_DIRTY to _PAGE_COW Yu-cheng Yu
2021-04-15 22:14 ` [PATCH v25 13/30] mm: Introduce VM_SHADOW_STACK for shadow stack memory Yu-cheng Yu
2021-04-15 22:14 ` [PATCH v25 14/30] x86/mm: Shadow Stack page fault error checking Yu-cheng Yu
2021-04-15 22:14 ` [PATCH v25 15/30] x86/mm: Update maybe_mkwrite() for shadow stack Yu-cheng Yu
2021-04-15 22:14 ` [PATCH v25 16/30] mm: Fixup places that call pte_mkwrite() directly Yu-cheng Yu
2021-04-23 10:13 ` Kirill A. Shutemov
2021-04-15 22:14 ` [PATCH v25 17/30] mm: Add guard pages around a shadow stack Yu-cheng Yu
2021-04-15 22:14 ` [PATCH v25 18/30] mm/mmap: Add shadow stack pages to memory accounting Yu-cheng Yu
2021-04-23 10:19 ` Kirill A. Shutemov
2021-04-15 22:14 ` [PATCH v25 19/30] mm: Update can_follow_write_pte() for shadow stack Yu-cheng Yu
2021-04-23 10:25 ` Kirill A. Shutemov
2021-04-15 22:14 ` [PATCH v25 20/30] mm/mprotect: Exclude shadow stack from preserve_write Yu-cheng Yu
2021-04-23 10:27 ` Kirill A. Shutemov
2021-04-15 22:14 ` [PATCH v25 21/30] mm: Re-introduce vm_flags to do_mmap() Yu-cheng Yu
2021-04-23 10:31 ` Kirill A. Shutemov
2021-04-23 15:59 ` Yu, Yu-cheng
2021-04-15 22:14 ` [PATCH v25 22/30] x86/cet/shstk: Add user-mode shadow stack support Yu-cheng Yu
2021-04-15 22:14 ` [PATCH v25 23/30] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2021-04-15 22:14 ` [PATCH v25 24/30] x86/cet/shstk: Introduce shadow stack token setup/verify routines Yu-cheng Yu
2021-04-15 22:14 ` [PATCH v25 25/30] x86/cet/shstk: Handle signals for shadow stack Yu-cheng Yu
2021-04-15 22:14 ` [PATCH v25 26/30] ELF: Introduce arch_setup_elf_property() Yu-cheng Yu
2021-04-15 22:14 ` Yu-cheng Yu [this message]
2021-04-15 22:14 ` [PATCH v25 28/30] mm: Move arch_calc_vm_prot_bits() to arch/x86/include/asm/mman.h Yu-cheng Yu
2021-04-26 6:31 ` Kirill A. Shutemov
2021-04-15 22:14 ` [PATCH v25 29/30] mm: Update arch_validate_flags() to include vma anonymous Yu-cheng Yu
2021-04-26 6:40 ` Kirill A. Shutemov
2021-04-26 11:11 ` Catalin Marinas
2021-04-26 17:56 ` Yu, Yu-cheng
2021-04-15 22:14 ` [PATCH v25 30/30] mm: Introduce PROT_SHSTK for shadow stack Yu-cheng Yu
2021-04-26 6:52 ` Kirill A. Shutemov
2021-04-26 18:00 ` Yu, Yu-cheng
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