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 v16 25/26] x86/cet/shstk: Add arch_prctl functions for shadow stack
Date: Wed, 9 Dec 2020 14:23:19 -0800 [thread overview]
Message-ID: <20201209222320.1724-26-yu-cheng.yu@intel.com> (raw)
In-Reply-To: <20201209222320.1724-1-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
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>
---
arch/x86/include/asm/cet.h | 3 ++
arch/x86/include/uapi/asm/prctl.h | 4 ++
arch/x86/kernel/Makefile | 2 +-
arch/x86/kernel/cet_prctl.c | 68 +++++++++++++++++++++++++++++++
arch/x86/kernel/process.c | 6 +--
5 files changed, 79 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 4b222aa1e18e..5e44605ae9c5 100644
--- a/arch/x86/include/asm/cet.h
+++ b/arch/x86/include/asm/cet.h
@@ -14,9 +14,11 @@ struct sc_ext;
struct cet_status {
unsigned long shstk_base;
unsigned long shstk_size;
+ unsigned int locked:1;
};
#ifdef CONFIG_X86_CET_USER
+int prctl_cet(int option, u64 arg2);
int cet_setup_shstk(void);
int cet_setup_thread_shstk(struct task_struct *p, unsigned long clone_flags);
void cet_disable_shstk(void);
@@ -25,6 +27,7 @@ int cet_verify_rstor_token(bool ia32, unsigned long ssp, unsigned long *new_ssp)
void cet_restore_signal(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, u64 arg2) { return -EINVAL; }
static inline int cet_setup_thread_shstk(struct task_struct *p,
unsigned long clone_flags) { return 0; }
static inline void cet_disable_shstk(void) {}
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 3f0e69457a90..d92f7cc71698 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -151,7 +151,7 @@ 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_CET_USER) += cet.o
+obj-$(CONFIG_X86_CET_USER) += cet.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..4197d985b5ff
--- /dev/null
+++ b/arch/x86/kernel/cet_prctl.c
@@ -0,0 +1,68 @@
+// 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 copy_status_to_user(struct cet_status *cet, u64 arg2)
+{
+ u64 buf[3] = {0, 0, 0};
+
+ if (cet->shstk_size) {
+ buf[0] |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
+ buf[1] = (u64)cet->shstk_base;
+ buf[2] = (u64)cet->shstk_size;
+ }
+
+ return copy_to_user((u64 __user *)arg2, buf, sizeof(buf));
+}
+
+int prctl_cet(int option, u64 arg2)
+{
+ struct cet_status *cet;
+ unsigned int features;
+
+ /*
+ * GLIBC's ENOTSUPP == EOPNOTSUPP == 95, and it does not recognize
+ * the kernel's ENOTSUPP (524). So return EOPNOTSUPP here.
+ */
+ if (!IS_ENABLED(CONFIG_X86_CET_USER))
+ return -EOPNOTSUPP;
+
+ cet = ¤t->thread.cet;
+
+ if (option == ARCH_X86_CET_STATUS)
+ return copy_status_to_user(cet, arg2);
+
+ if (!static_cpu_has(X86_FEATURE_CET))
+ return -EOPNOTSUPP;
+
+ switch (option) {
+ case ARCH_X86_CET_DISABLE:
+ if (cet->locked)
+ return -EPERM;
+
+ features = (unsigned int)arg2;
+
+ if (features & GNU_PROPERTY_X86_FEATURE_1_INVAL)
+ return -EINVAL;
+ if (features & GNU_PROPERTY_X86_FEATURE_1_SHSTK)
+ cet_disable_shstk();
+ return 0;
+
+ case ARCH_X86_CET_LOCK:
+ cet->locked = 1;
+ return 0;
+
+ default:
+ return -ENOSYS;
+ }
+}
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 3af6b36e1a5c..9e11e5f589f3 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -979,14 +979,14 @@ 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:[~2020-12-09 22:26 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-09 22:22 [PATCH v16 00/26] Control-flow Enforcement: Shadow Stack Yu-cheng Yu
2020-12-09 22:22 ` [PATCH v16 01/26] Documentation/x86: Add CET description Yu-cheng Yu
2020-12-09 22:22 ` [PATCH v16 02/26] x86/cet/shstk: Add Kconfig option for user-mode control-flow protection Yu-cheng Yu
2020-12-29 12:39 ` Borislav Petkov
2020-12-29 16:34 ` Yu, Yu-cheng
2020-12-29 18:54 ` Borislav Petkov
2020-12-29 19:45 ` Yu, Yu-cheng
2020-12-09 22:22 ` [PATCH v16 03/26] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET) Yu-cheng Yu
2020-12-09 22:22 ` [PATCH v16 04/26] x86/cpufeatures: Introduce X86_FEATURE_CET and setup functions Yu-cheng Yu
2020-12-09 22:22 ` [PATCH v16 05/26] x86/fpu/xstate: Introduce CET MSR and XSAVES supervisor states Yu-cheng Yu
2020-12-09 22:23 ` [PATCH v16 06/26] x86/cet: Add control-protection fault handler Yu-cheng Yu
2020-12-09 22:23 ` [PATCH v16 07/26] x86/mm: Remove _PAGE_DIRTY from kernel RO pages Yu-cheng Yu
2020-12-09 22:23 ` [PATCH v16 08/26] x86/mm: Introduce _PAGE_COW Yu-cheng Yu
2020-12-09 22:23 ` [PATCH v16 09/26] drm/i915/gvt: Change _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2020-12-09 22:23 ` [PATCH v16 10/26] x86/mm: Update pte_modify for _PAGE_COW Yu-cheng Yu
2020-12-09 22:23 ` [PATCH v16 11/26] x86/mm: Update ptep_set_wrprotect() and pmdp_set_wrprotect() for transition from _PAGE_DIRTY to _PAGE_COW Yu-cheng Yu
2020-12-09 22:23 ` [PATCH v16 12/26] mm: Introduce VM_SHSTK for shadow stack memory Yu-cheng Yu
2020-12-09 22:23 ` [PATCH v16 13/26] x86/mm: Shadow Stack page fault error checking Yu-cheng Yu
2020-12-09 22:23 ` [PATCH v16 14/26] x86/mm: Update maybe_mkwrite() for shadow stack Yu-cheng Yu
2020-12-09 22:23 ` [PATCH v16 15/26] mm: Fixup places that call pte_mkwrite() directly Yu-cheng Yu
2020-12-09 22:23 ` [PATCH v16 16/26] mm: Add guard pages around a shadow stack Yu-cheng Yu
2020-12-09 22:23 ` [PATCH v16 17/26] mm/mmap: Add shadow stack pages to memory accounting Yu-cheng Yu
2020-12-09 22:23 ` [PATCH v16 18/26] mm: Update can_follow_write_pte() for shadow stack Yu-cheng Yu
2020-12-09 22:23 ` [PATCH v16 19/26] mm: Re-introduce vm_flags to do_mmap() Yu-cheng Yu
2020-12-09 22:23 ` [PATCH v16 20/26] x86/cet/shstk: User-mode shadow stack support Yu-cheng Yu
2020-12-09 22:23 ` [PATCH v16 21/26] x86/cet/shstk: Handle signals for shadow stack Yu-cheng Yu
2020-12-09 22:23 ` [PATCH v16 22/26] binfmt_elf: Define GNU_PROPERTY_X86_FEATURE_1_AND properties Yu-cheng Yu
2020-12-09 22:23 ` [PATCH v16 23/26] ELF: Introduce arch_setup_elf_property() Yu-cheng Yu
2020-12-09 22:23 ` [PATCH v16 24/26] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2020-12-09 22:23 ` Yu-cheng Yu [this message]
2020-12-09 22:23 ` [PATCH v16 26/26] mm: Introduce PROT_SHSTK for " Yu-cheng Yu
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