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>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Subject: [PATCH v17 20/26] x86/cet/shstk: User-mode shadow stack support
Date: Tue, 29 Dec 2020 13:30:47 -0800 [thread overview]
Message-ID: <20201229213053.16395-21-yu-cheng.yu@intel.com> (raw)
In-Reply-To: <20201229213053.16395-1-yu-cheng.yu@intel.com>
Introduce basic shadow stack enabling/disabling/allocation routines.
A task's shadow stack is allocated from memory with VM_SHSTK flag and has
a fixed size of min(RLIMIT_STACK, 4GB).
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
arch/x86/include/asm/cet.h | 28 ++++++
arch/x86/include/asm/processor.h | 5 ++
arch/x86/kernel/Makefile | 2 +
arch/x86/kernel/cet.c | 147 +++++++++++++++++++++++++++++++
4 files changed, 182 insertions(+)
create mode 100644 arch/x86/include/asm/cet.h
create mode 100644 arch/x86/kernel/cet.c
diff --git a/arch/x86/include/asm/cet.h b/arch/x86/include/asm/cet.h
new file mode 100644
index 000000000000..6d0df5c26c22
--- /dev/null
+++ b/arch/x86/include/asm/cet.h
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_CET_H
+#define _ASM_X86_CET_H
+
+#ifndef __ASSEMBLY__
+#include <linux/types.h>
+
+struct task_struct;
+/*
+ * Per-thread CET status
+ */
+struct cet_status {
+ unsigned long shstk_base;
+ unsigned long shstk_size;
+};
+
+#ifdef CONFIG_X86_CET_USER
+int cet_setup_shstk(void);
+void cet_disable_shstk(void);
+void cet_free_shstk(struct task_struct *p);
+#else
+static inline void cet_disable_shstk(void) {}
+static inline void cet_free_shstk(struct task_struct *p) {}
+#endif
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_X86_CET_H */
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index c20a52b5534b..2b8202f35fde 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -27,6 +27,7 @@ struct vm86;
#include <asm/unwind_hints.h>
#include <asm/vmxfeatures.h>
#include <asm/vdso/processor.h>
+#include <asm/cet.h>
#include <linux/personality.h>
#include <linux/cache.h>
@@ -536,6 +537,10 @@ struct thread_struct {
unsigned int sig_on_uaccess_err:1;
+#ifdef CONFIG_X86_CET_USER
+ struct cet_status cet;
+#endif
+
/* Floating point and extended processor state */
struct fpu fpu;
/*
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 5eeb808eb024..07cee6125a3c 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -151,6 +151,8 @@ 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_CET_USER) += cet.o
+
###
# 64 bit specific files
ifeq ($(CONFIG_X86_64),y)
diff --git a/arch/x86/kernel/cet.c b/arch/x86/kernel/cet.c
new file mode 100644
index 000000000000..f8b0a077594f
--- /dev/null
+++ b/arch/x86/kernel/cet.c
@@ -0,0 +1,147 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * cet.c - Control-flow Enforcement (CET)
+ *
+ * Copyright (c) 2019, Intel Corporation.
+ * Yu-cheng Yu <yu-cheng.yu@intel.com>
+ */
+
+#include <linux/types.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/sched/signal.h>
+#include <linux/compat.h>
+#include <asm/msr.h>
+#include <asm/user.h>
+#include <asm/fpu/internal.h>
+#include <asm/fpu/xstate.h>
+#include <asm/fpu/types.h>
+#include <asm/cet.h>
+
+static void start_update_msrs(void)
+{
+ fpregs_lock();
+ if (test_thread_flag(TIF_NEED_FPU_LOAD))
+ __fpregs_load_activate();
+}
+
+static void end_update_msrs(void)
+{
+ fpregs_unlock();
+}
+
+static unsigned long cet_get_shstk_addr(void)
+{
+ struct fpu *fpu = ¤t->thread.fpu;
+ unsigned long ssp = 0;
+
+ fpregs_lock();
+
+ if (fpregs_state_valid(fpu, smp_processor_id())) {
+ rdmsrl(MSR_IA32_PL3_SSP, ssp);
+ } else {
+ struct cet_user_state *p;
+
+ p = get_xsave_addr(&fpu->state.xsave, XFEATURE_CET_USER);
+ if (p)
+ ssp = p->user_ssp;
+ }
+
+ fpregs_unlock();
+ return ssp;
+}
+
+static unsigned long alloc_shstk(unsigned long size, int flags)
+{
+ struct mm_struct *mm = current->mm;
+ unsigned long addr, populate;
+
+ /* VM_SHSTK requires MAP_ANONYMOUS, MAP_PRIVATE */
+ flags |= MAP_ANONYMOUS | MAP_PRIVATE;
+
+ mmap_write_lock(mm);
+ addr = do_mmap(NULL, 0, size, PROT_READ, flags, VM_SHSTK, 0,
+ &populate, NULL);
+ mmap_write_unlock(mm);
+
+ if (populate)
+ mm_populate(addr, populate);
+
+ return addr;
+}
+
+int cet_setup_shstk(void)
+{
+ unsigned long addr, size;
+ struct cet_status *cet = ¤t->thread.cet;
+
+ if (!static_cpu_has(X86_FEATURE_SHSTK))
+ return -EOPNOTSUPP;
+
+ size = round_up(min(rlimit(RLIMIT_STACK), 1UL << 32), PAGE_SIZE);
+ addr = alloc_shstk(size, 0);
+
+ if (IS_ERR_VALUE(addr))
+ return PTR_ERR((void *)addr);
+
+ cet->shstk_base = addr;
+ cet->shstk_size = size;
+
+ start_update_msrs();
+ wrmsrl(MSR_IA32_PL3_SSP, addr + size);
+ wrmsrl(MSR_IA32_U_CET, CET_SHSTK_EN);
+ end_update_msrs();
+ return 0;
+}
+
+void cet_disable_shstk(void)
+{
+ struct cet_status *cet = ¤t->thread.cet;
+ u64 msr_val;
+
+ if (!static_cpu_has(X86_FEATURE_SHSTK) ||
+ !cet->shstk_size || !cet->shstk_base)
+ return;
+
+ start_update_msrs();
+ rdmsrl(MSR_IA32_U_CET, msr_val);
+ wrmsrl(MSR_IA32_U_CET, msr_val & ~CET_SHSTK_EN);
+ wrmsrl(MSR_IA32_PL3_SSP, 0);
+ end_update_msrs();
+
+ cet_free_shstk(current);
+}
+
+void cet_free_shstk(struct task_struct *tsk)
+{
+ struct cet_status *cet = &tsk->thread.cet;
+
+ if (!static_cpu_has(X86_FEATURE_SHSTK) ||
+ !cet->shstk_size || !cet->shstk_base)
+ return;
+
+ if (!tsk->mm || (tsk->mm != current->mm))
+ return;
+
+ while (1) {
+ int r;
+
+ r = vm_munmap(cet->shstk_base, cet->shstk_size);
+
+ /*
+ * Retry if mmap_lock is not available.
+ */
+ if (r == -EINTR) {
+ cond_resched();
+ continue;
+ }
+
+ WARN_ON_ONCE(r);
+ break;
+ }
+
+ cet->shstk_base = 0;
+ cet->shstk_size = 0;
+}
--
2.21.0
next prev parent reply other threads:[~2020-12-29 21:34 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-29 21:30 [PATCH v17 00/26] Control-flow Enforcement: Shadow Stack Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 01/26] Documentation/x86: Add CET description Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 02/26] x86/cet/shstk: Add Kconfig option for user-mode control-flow protection Yu-cheng Yu
2021-01-19 11:06 ` Borislav Petkov
2021-01-19 18:10 ` Yu, Yu-cheng
2020-12-29 21:30 ` [PATCH v17 03/26] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET) Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 04/26] x86/cpufeatures: Introduce X86_FEATURE_CET and setup functions Yu-cheng Yu
2021-01-11 17:56 ` Borislav Petkov
2021-01-11 20:25 ` Yu, Yu-cheng
2021-01-11 23:09 ` Yu-cheng Yu
2021-01-12 0:09 ` Yu, Yu-cheng
2021-01-12 12:38 ` Borislav Petkov
2021-01-12 23:02 ` Yu, Yu-cheng
2021-01-13 10:04 ` Borislav Petkov
2020-12-29 21:30 ` [PATCH v17 05/26] x86/fpu/xstate: Introduce CET MSR and XSAVES supervisor states Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 06/26] x86/cet: Add control-protection fault handler Yu-cheng Yu
2021-01-19 12:04 ` Borislav Petkov
2021-01-19 19:36 ` Yu, Yu-cheng
2020-12-29 21:30 ` [PATCH v17 07/26] x86/mm: Remove _PAGE_DIRTY from kernel RO pages Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 08/26] x86/mm: Introduce _PAGE_COW Yu-cheng Yu
2021-01-21 18:44 ` Borislav Petkov
2021-01-21 20:16 ` Yu, Yu-cheng
2021-01-21 20:20 ` Dave Hansen
2021-01-21 20:26 ` Dave Hansen
2021-01-21 20:44 ` Yu, Yu-cheng
2021-01-21 20:41 ` Borislav Petkov
2021-01-21 21:40 ` Yu, Yu-cheng
2021-01-21 22:16 ` David Laight
2021-01-21 22:19 ` Randy Dunlap
2021-01-21 22:32 ` David Laight
2021-01-22 21:54 ` Yu, Yu-cheng
2020-12-29 21:30 ` [PATCH v17 09/26] drm/i915/gvt: Change _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 10/26] x86/mm: Update pte_modify for _PAGE_COW Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 11/26] x86/mm: Update ptep_set_wrprotect() and pmdp_set_wrprotect() for transition from _PAGE_DIRTY to _PAGE_COW Yu-cheng Yu
2021-01-25 18:27 ` Borislav Petkov
2021-01-25 21:27 ` Yu, Yu-cheng
2021-01-25 21:55 ` Borislav Petkov
2021-01-25 22:18 ` Yu, Yu-cheng
2021-01-26 10:24 ` Borislav Petkov
2021-01-26 16:45 ` Yu, Yu-cheng
2021-01-26 8:46 ` Peter Zijlstra
2021-01-26 9:40 ` Peter Zijlstra
2021-01-26 16:43 ` Yu, Yu-cheng
2020-12-29 21:30 ` [PATCH v17 12/26] mm: Introduce VM_SHSTK for shadow stack memory Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 13/26] x86/mm: Shadow Stack page fault error checking Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 14/26] x86/mm: Update maybe_mkwrite() for shadow stack Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 15/26] mm: Fixup places that call pte_mkwrite() directly Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 16/26] mm: Add guard pages around a shadow stack Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 17/26] mm/mmap: Add shadow stack pages to memory accounting Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 18/26] mm: Update can_follow_write_pte() for shadow stack Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 19/26] mm: Re-introduce vm_flags to do_mmap() Yu-cheng Yu
2020-12-29 21:30 ` Yu-cheng Yu [this message]
2020-12-29 21:30 ` [PATCH v17 21/26] x86/cet/shstk: Handle signals for shadow stack Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 22/26] binfmt_elf: Define GNU_PROPERTY_X86_FEATURE_1_AND properties Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 23/26] ELF: Introduce arch_setup_elf_property() Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 24/26] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 25/26] x86/cet/shstk: Add arch_prctl functions for " Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 26/26] mm: Introduce PROT_SHSTK " Yu-cheng Yu
2021-01-04 20:08 ` [PATCH v17 00/26] Control-flow Enforcement: Shadow Stack Yu, Yu-cheng
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