From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yu-cheng Yu Subject: [PATCH v7 12/14] x86/vsyscall/64: Fixup shadow stack and branch tracking for vsyscall Date: Thu, 6 Jun 2019 13:09:24 -0700 Message-ID: <20190606200926.4029-13-yu-cheng.yu@intel.com> References: <20190606200926.4029-1-yu-cheng.yu@intel.com> Return-path: In-Reply-To: <20190606200926.4029-1-yu-cheng.yu@intel.com> Sender: linux-kernel-owner@vger.kernel.org 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 , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit Cc: Yu-cheng Yu List-Id: linux-api@vger.kernel.org When emulating a RET, also unwind the task's shadow stack and cancel the current branch tracking status. Signed-off-by: Yu-cheng Yu --- arch/x86/entry/vsyscall/vsyscall_64.c | 28 +++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/arch/x86/entry/vsyscall/vsyscall_64.c b/arch/x86/entry/vsyscall/vsyscall_64.c index d9d81ad7a400..6869ef9d1e8b 100644 --- a/arch/x86/entry/vsyscall/vsyscall_64.c +++ b/arch/x86/entry/vsyscall/vsyscall_64.c @@ -38,6 +38,8 @@ #include #include #include +#include +#include #define CREATE_TRACE_POINTS #include "vsyscall_trace.h" @@ -92,6 +94,30 @@ static int addr_to_vsyscall_nr(unsigned long addr) return nr; } +void fixup_shstk(void) +{ +#ifdef CONFIG_X86_INTEL_SHADOW_STACK_USER + u64 r; + + if (current->thread.cet.shstk_enabled) { + rdmsrl(MSR_IA32_PL3_SSP, r); + wrmsrl(MSR_IA32_PL3_SSP, r + 8); + } +#endif +} + +void fixup_ibt(void) +{ +#ifdef CONFIG_X86_INTEL_BRANCH_TRACKING_USER + u64 r; + + if (current->thread.cet.ibt_enabled) { + rdmsrl(MSR_IA32_U_CET, r); + wrmsrl(MSR_IA32_U_CET, r & ~MSR_IA32_CET_WAIT_ENDBR); + } +#endif +} + static bool write_ok_or_segv(unsigned long ptr, size_t size) { /* @@ -265,6 +291,8 @@ bool emulate_vsyscall(struct pt_regs *regs, unsigned long address) /* Emulate a ret instruction. */ regs->ip = caller; regs->sp += 8; + fixup_shstk(); + fixup_ibt(); return true; sigsegv: -- 2.17.1