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[192.55.52.88]) by mx.google.com with ESMTPS id z73-v6si6610727pgd.471.2018.08.30.07.43.46 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 30 Aug 2018 07:43:46 -0700 (PDT) Received-SPF: pass (google.com: domain of yu-cheng.yu@intel.com designates 192.55.52.88 as permitted sender) client-ip=192.55.52.88; Authentication-Results: mx.google.com; spf=pass (google.com: domain of yu-cheng.yu@intel.com designates 192.55.52.88 as permitted sender) smtp.mailfrom=yu-cheng.yu@intel.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 30 Aug 2018 07:43:44 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.53,307,1531810800"; d="scan'208";a="67186736" Received: from 2b52.sc.intel.com ([143.183.136.52]) by fmsmga008.fm.intel.com with ESMTP; 30 Aug 2018 07:43:43 -0700 From: Yu-cheng Yu To: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , 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 , Andy Lutomirski , Balbir Singh , Cyrill Gorcunov , Dave Hansen , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , "Ravi V. Shankar" , Vedvyas Shanbhogue Cc: Yu-cheng Yu Subject: [RFC PATCH v3 23/24] x86/cet/shstk: Add arch_prctl functions for Shadow Stack Date: Thu, 30 Aug 2018 07:39:03 -0700 Message-Id: <20180830143904.3168-24-yu-cheng.yu@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180830143904.3168-1-yu-cheng.yu@intel.com> References: <20180830143904.3168-1-yu-cheng.yu@intel.com> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: X-Virus-Scanned: ClamAV using ClamSMTP arch_prctl(ARCH_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_CET_DISABLE, unsigned long features) Disable CET features specified in 'features'. Return -EPERM if CET is locked. arch_prctl(ARCH_CET_LOCK) Lock in CET feature. arch_prctl(ARCH_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. Signed-off-by: H.J. Lu Signed-off-by: Yu-cheng Yu --- 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 | 27 +++++++++++ arch/x86/kernel/cet_prctl.c | 79 +++++++++++++++++++++++++++++++ arch/x86/kernel/process.c | 5 ++ 6 files changed, 122 insertions(+), 1 deletion(-) 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 b7b33e1026bb..212bd68e31d3 100644 --- a/arch/x86/include/asm/cet.h +++ b/arch/x86/include/asm/cet.h @@ -12,19 +12,24 @@ struct task_struct; 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(unsigned long ssp); int cet_setup_signal(bool ia32, unsigned long rstor, unsigned long *new_ssp); #else +static inline int prctl_cet(int option, unsigned long arg2) { return 0; } static inline int cet_setup_shstk(void) { return 0; } 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(unsigned long ssp) { return 0; } diff --git a/arch/x86/include/uapi/asm/prctl.h b/arch/x86/include/uapi/asm/prctl.h index 5a6aac9fa41f..3aec1088e01d 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_CET_STATUS 0x3001 +#define ARCH_CET_DISABLE 0x3002 +#define ARCH_CET_LOCK 0x3003 +#define ARCH_CET_ALLOC_SHSTK 0x3004 + #endif /* _ASM_X86_PRCTL_H */ diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 36b14ef410c8..b9e6cdc6b4f7 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -139,7 +139,7 @@ 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-$(CONFIG_X86_INTEL_CET) += cet.o cet_prctl.o obj-$(CONFIG_ARCH_HAS_PROGRAM_PROPERTIES) += elf.o diff --git a/arch/x86/kernel/cet.c b/arch/x86/kernel/cet.c index ce0b3b7b1160..1c2689738604 100644 --- a/arch/x86/kernel/cet.c +++ b/arch/x86/kernel/cet.c @@ -110,6 +110,33 @@ 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(0, len, PROT_READ, + MAP_ANONYMOUS | MAP_PRIVATE, VM_SHSTK); + 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 |= 1; + ssp -= 8; + + if (write_user_shstk_64(ssp, token)) + 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..c4b7c19f5040 --- /dev/null +++ b/arch/x86/kernel/cet_prctl.c @@ -0,0 +1,79 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* See Documentation/x86/intel_cet.txt. */ + +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 shstk_size = 0; + + if (get_user(shstk_size, (unsigned long __user *)arg2)) + return -EFAULT; + + err = cet_alloc_shstk(&shstk_size); + if (err) + return err; + + if (put_user(shstk_size, (unsigned long __user *)arg2)) + return -EFAULT; + + return 0; +} + +int prctl_cet(int option, unsigned long arg2) +{ + if (!cpu_feature_enabled(X86_FEATURE_SHSTK)) + return -EINVAL; + + switch (option) { + case ARCH_CET_STATUS: + return handle_get_status(arg2); + + case ARCH_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_CET_LOCK: + current->thread.cet.locked = 1; + return 0; + + case ARCH_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 440f012ef925..251b8714f9a3 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -792,6 +792,11 @@ 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); + case ARCH_CET_STATUS: + case ARCH_CET_DISABLE: + case ARCH_CET_LOCK: + case ARCH_CET_ALLOC_SHSTK: + return prctl_cet(option, cpuid_enabled); } return -EINVAL;