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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 , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue Cc: Yu-cheng Yu Subject: [RFC PATCH v4 6/9] x86/cet/ibt: Add arch_prctl functions for IBT Date: Fri, 21 Sep 2018 08:05:50 -0700 Message-Id: <20180921150553.21016-7-yu-cheng.yu@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180921150553.21016-1-yu-cheng.yu@intel.com> References: <20180921150553.21016-1-yu-cheng.yu@intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Update ARCH_CET_STATUS and ARCH_CET_DISABLE to include Indirect Branch Tracking features. Introduce: arch_prctl(ARCH_CET_LEGACY_BITMAP, unsigned long *addr) Enable the Indirect Branch Tracking legacy code bitmap. The parameter 'addr' is a pointer to a user buffer. On returning to the caller, the kernel fills the following: *addr = IBT bitmap base address *(addr + 1) = IBT bitmap size Signed-off-by: H.J. Lu Signed-off-by: Yu-cheng Yu --- arch/x86/include/uapi/asm/prctl.h | 1 + arch/x86/kernel/cet_prctl.c | 38 ++++++++++++++++++++++++++++++- arch/x86/kernel/process.c | 1 + 3 files changed, 39 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/uapi/asm/prctl.h b/arch/x86/include/uapi/asm/prctl.h index 3aec1088e01d..31d2465f9caf 100644 --- a/arch/x86/include/uapi/asm/prctl.h +++ b/arch/x86/include/uapi/asm/prctl.h @@ -18,5 +18,6 @@ #define ARCH_CET_DISABLE 0x3002 #define ARCH_CET_LOCK 0x3003 #define ARCH_CET_ALLOC_SHSTK 0x3004 +#define ARCH_CET_LEGACY_BITMAP 0x3005 #endif /* _ASM_X86_PRCTL_H */ diff --git a/arch/x86/kernel/cet_prctl.c b/arch/x86/kernel/cet_prctl.c index c4b7c19f5040..df47b5ebc3f4 100644 --- a/arch/x86/kernel/cet_prctl.c +++ b/arch/x86/kernel/cet_prctl.c @@ -20,6 +20,8 @@ static int handle_get_status(unsigned long arg2) if (current->thread.cet.shstk_enabled) features |= GNU_PROPERTY_X86_FEATURE_1_SHSTK; + if (current->thread.cet.ibt_enabled) + features |= GNU_PROPERTY_X86_FEATURE_1_IBT; shstk_base = current->thread.cet.shstk_base; shstk_size = current->thread.cet.shstk_size; @@ -49,9 +51,35 @@ static int handle_alloc_shstk(unsigned long arg2) return 0; } +static int handle_bitmap(unsigned long arg2) +{ + unsigned long addr, size; + + if (current->thread.cet.ibt_enabled) { + int err; + + err = cet_setup_ibt_bitmap(); + if (err) + return err; + + addr = current->thread.cet.ibt_bitmap_addr; + size = current->thread.cet.ibt_bitmap_size; + } else { + addr = 0; + size = 0; + } + + if (put_user(addr, (unsigned long __user *)arg2) || + put_user(size, (unsigned long __user *)arg2 + 1)) + return -EFAULT; + + return 0; +} + int prctl_cet(int option, unsigned long arg2) { - if (!cpu_feature_enabled(X86_FEATURE_SHSTK)) + if (!cpu_feature_enabled(X86_FEATURE_SHSTK) && + !cpu_feature_enabled(X86_FEATURE_IBT)) return -EINVAL; switch (option) { @@ -63,6 +91,8 @@ int prctl_cet(int option, unsigned long arg2) return -EPERM; if (arg2 & GNU_PROPERTY_X86_FEATURE_1_SHSTK) cet_disable_free_shstk(current); + if (arg2 & GNU_PROPERTY_X86_FEATURE_1_IBT) + cet_disable_ibt(); return 0; @@ -73,6 +103,12 @@ int prctl_cet(int option, unsigned long arg2) case ARCH_CET_ALLOC_SHSTK: return handle_alloc_shstk(arg2); + /* + * Allocate legacy bitmap and return address & size to user. + */ + case ARCH_CET_LEGACY_BITMAP: + return handle_bitmap(arg2); + default: return -EINVAL; } diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index ac0ea9c7e89f..aea15a9b6a3e 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -797,6 +797,7 @@ long do_arch_prctl_common(struct task_struct *task, int option, case ARCH_CET_DISABLE: case ARCH_CET_LOCK: case ARCH_CET_ALLOC_SHSTK: + case ARCH_CET_LEGACY_BITMAP: return prctl_cet(option, cpuid_enabled); } -- 2.17.1