From patchwork Thu Aug 22 15:10:59 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joey Gouly X-Patchwork-Id: 821479 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id CAC971CC8BD; Thu, 22 Aug 2024 15:12:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724339555; cv=none; b=mxZ49SENHMIsp1evSmb2v6DtVerDwCc9DgHyiRdctA/0/SLL2QJThs4H2/dFT5AK9TcARFOKEZBoWa+v8IKGGz7KRkcAGLhrLpelFMb9oQdIi6oPvzFwKIfIFU5iGNIA0iMqYWNn0bP26HLAWFRnrjV+fZHhcl/9amRCdgLXYV8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724339555; c=relaxed/simple; bh=celeztTJt63WGHGCIeSnJZJIzvaNwwTiEVLT6sIigMc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=H5u9dqPCj4Ad712FO83TnwtcetvKOWfdS3Xpr8uyGmPX7tDYQlC+qiC0xwWQav7fGIqd8/gkAGHdY8DtfPYN7Y/KsQpx2NJz5gNNkc4KgfRNd0LVQNnrjbvsIaTnwLCH8l5ktuD1tKWhZ/cCjRUNcAB1YJgrHHRot3IOe9Pb0Cg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8D58515A1; Thu, 22 Aug 2024 08:12:59 -0700 (PDT) Received: from e124191.cambridge.arm.com (e124191.cambridge.arm.com [10.1.197.45]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5BB9A3F58B; Thu, 22 Aug 2024 08:12:29 -0700 (PDT) From: Joey Gouly To: linux-arm-kernel@lists.infradead.org Cc: nd@arm.com, akpm@linux-foundation.org, aneesh.kumar@kernel.org, aneesh.kumar@linux.ibm.com, anshuman.khandual@arm.com, bp@alien8.de, broonie@kernel.org, catalin.marinas@arm.com, christophe.leroy@csgroup.eu, dave.hansen@linux.intel.com, hpa@zytor.com, joey.gouly@arm.com, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, maz@kernel.org, mingo@redhat.com, mpe@ellerman.id.au, naveen.n.rao@linux.ibm.com, npiggin@gmail.com, oliver.upton@linux.dev, shuah@kernel.org, skhan@linuxfoundation.org, szabolcs.nagy@arm.com, tglx@linutronix.de, will@kernel.org, x86@kernel.org, kvmarm@lists.linux.dev, linux-kselftest@vger.kernel.org Subject: [PATCH v5 16/30] arm64: handle PKEY/POE faults Date: Thu, 22 Aug 2024 16:10:59 +0100 Message-Id: <20240822151113.1479789-17-joey.gouly@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240822151113.1479789-1-joey.gouly@arm.com> References: <20240822151113.1479789-1-joey.gouly@arm.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 If a memory fault occurs that is due to an overlay/pkey fault, report that to userspace with a SEGV_PKUERR. Signed-off-by: Joey Gouly Cc: Catalin Marinas Cc: Will Deacon Reviewed-by: Catalin Marinas --- arch/arm64/include/asm/traps.h | 1 + arch/arm64/kernel/traps.c | 6 ++++ arch/arm64/mm/fault.c | 55 +++++++++++++++++++++++++++++++++- 3 files changed, 61 insertions(+), 1 deletion(-) diff --git arch/arm64/include/asm/traps.h arch/arm64/include/asm/traps.h index eefe766d6161..d780d1bd2eac 100644 --- arch/arm64/include/asm/traps.h +++ arch/arm64/include/asm/traps.h @@ -25,6 +25,7 @@ try_emulate_armv8_deprecated(struct pt_regs *regs, u32 insn) void force_signal_inject(int signal, int code, unsigned long address, unsigned long err); void arm64_notify_segfault(unsigned long addr); void arm64_force_sig_fault(int signo, int code, unsigned long far, const char *str); +void arm64_force_sig_fault_pkey(unsigned long far, const char *str, int pkey); void arm64_force_sig_mceerr(int code, unsigned long far, short lsb, const char *str); void arm64_force_sig_ptrace_errno_trap(int errno, unsigned long far, const char *str); diff --git arch/arm64/kernel/traps.c arch/arm64/kernel/traps.c index 9e22683aa921..9a11bb0db284 100644 --- arch/arm64/kernel/traps.c +++ arch/arm64/kernel/traps.c @@ -273,6 +273,12 @@ void arm64_force_sig_fault(int signo, int code, unsigned long far, force_sig_fault(signo, code, (void __user *)far); } +void arm64_force_sig_fault_pkey(unsigned long far, const char *str, int pkey) +{ + arm64_show_signal(SIGSEGV, str); + force_sig_pkuerr((void __user *)far, pkey); +} + void arm64_force_sig_mceerr(int code, unsigned long far, short lsb, const char *str) { diff --git arch/arm64/mm/fault.c arch/arm64/mm/fault.c index 451ba7cbd5ad..a68055150950 100644 --- arch/arm64/mm/fault.c +++ arch/arm64/mm/fault.c @@ -23,6 +23,7 @@ #include #include #include +#include #include #include @@ -486,6 +487,23 @@ static void do_bad_area(unsigned long far, unsigned long esr, } } +static bool fault_from_pkey(unsigned long esr, struct vm_area_struct *vma, + unsigned int mm_flags) +{ + unsigned long iss2 = ESR_ELx_ISS2(esr); + + if (!system_supports_poe()) + return false; + + if (iss2 & ESR_ELx_Overlay) + return true; + + return !arch_vma_access_permitted(vma, + mm_flags & FAULT_FLAG_WRITE, + mm_flags & FAULT_FLAG_INSTRUCTION, + false); +} + static bool is_el0_instruction_abort(unsigned long esr) { return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_LOW; @@ -511,6 +529,7 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr, unsigned long addr = untagged_addr(far); struct vm_area_struct *vma; int si_code; + int pkey = -1; if (kprobe_page_fault(regs, esr)) return 0; @@ -575,6 +594,16 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr, count_vm_vma_lock_event(VMA_LOCK_SUCCESS); goto bad_area; } + + if (fault_from_pkey(esr, vma, mm_flags)) { + pkey = vma_pkey(vma); + vma_end_read(vma); + fault = 0; + si_code = SEGV_PKUERR; + count_vm_vma_lock_event(VMA_LOCK_SUCCESS); + goto bad_area; + } + fault = handle_mm_fault(vma, addr, mm_flags | FAULT_FLAG_VMA_LOCK, regs); if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED))) vma_end_read(vma); @@ -610,7 +639,16 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr, goto bad_area; } + if (fault_from_pkey(esr, vma, mm_flags)) { + pkey = vma_pkey(vma); + mmap_read_unlock(mm); + fault = 0; + si_code = SEGV_PKUERR; + goto bad_area; + } + fault = handle_mm_fault(vma, addr, mm_flags, regs); + /* Quick path to respond to signals */ if (fault_signal_pending(fault, regs)) { if (!user_mode(regs)) @@ -669,8 +707,23 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr, arm64_force_sig_mceerr(BUS_MCEERR_AR, far, lsb, inf->name); } else { + /* + * The pkey value that we return to userspace can be different + * from the pkey that caused the fault. + * + * 1. T1 : mprotect_key(foo, PAGE_SIZE, pkey=4); + * 2. T1 : set POR_EL0 to deny access to pkey=4, touches, page + * 3. T1 : faults... + * 4. T2: mprotect_key(foo, PAGE_SIZE, pkey=5); + * 5. T1 : enters fault handler, takes mmap_lock, etc... + * 6. T1 : reaches here, sees vma_pkey(vma)=5, when we really + * faulted on a pte with its pkey=4. + */ /* Something tried to access memory that out of memory map */ - arm64_force_sig_fault(SIGSEGV, si_code, far, inf->name); + if (si_code == SEGV_PKUERR) + arm64_force_sig_fault_pkey(far, inf->name, pkey); + else + arm64_force_sig_fault(SIGSEGV, si_code, far, inf->name); } return 0;