From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: ACJfBotg6dxJVyMXu6jvcn1Tgi5c/fKqATJd69khJToCerYp8Zc2CGPvHlN9jQ9KPwVQJ9EHB1FQ ARC-Seal: i=1; a=rsa-sha256; t=1516327148; cv=none; d=google.com; s=arc-20160816; b=MEI6MwqQWxRtsc1sNUzNUoYuvfSGcl0tizVFi6+3KcJjuj+0dpRq6oFJB+aYaWJgP+ 40Xpd56Jmh7KlQ/MywvGhE7aW4yUFgrVK7sxpPPmfQnNrESTBmU7IYqpDeRrY6KPX7Z7 ce3lPFgTzIczGdcuJ4B43KMbxyz86jtC/gGp6fUZHnjWexVxaLgoWrH9c28ZXQLAeq7s r8F5xMNFhfmAZXBy+2kkFme9k2VCTizFpdDUDXYxl56CPAV2BC12gPO/53Ky6XuDdwJD j1Y2Nji4e9cjW2H7Hssh3CxwztAcYebdBcIp0+7jCEK+tDGbGjsmoDfOGWLL1Wt1lC32 uhKg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:references:in-reply-to:message-id:date :subject:cc:to:from:dkim-signature:arc-authentication-results; bh=834saSS/sHWC6W9JHCgPzkxyMUg7LMXHvbWS9ncBK5Q=; b=Cik/W+7K94SLXmQKToI4E4OMUKxKS0XYEynWBT0PZaKtGvPsQjLqf6EWLUiL0R/9yr v74OubK40x8zDAL1BmeYQreri79ibnkPO6K1sfklFyHFqr0xGsYP+yWuOPIPLEQRaVOX vBZMKqqb5gDJX+7TSXiSS3w2veWMPkv9q8EYj2w8a1fze2Qyc2b9AVtCrY/ycugZwpAS jByFE7Qxr3F8Jegd75TSt7cPfNh6PUDLxP4m+T3k13iIhkobZcMYjQB7WS1vyqDYk5YE QibDkQScP9bp9J/JFKqz0dTMRDPjv+BQfbX0N2NFwSdOohdvJVYGc1yhahExbeyHrKw/ 7qxQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=neutral (body hash did not verify) header.i=@gmail.com header.s=20161025 header.b=J7wE+mpd; spf=pass (google.com: best guess record for domain of linux-kselftest-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kselftest-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=ibm.com Authentication-Results: mx.google.com; dkim=neutral (body hash did not verify) header.i=@gmail.com header.s=20161025 header.b=J7wE+mpd; spf=pass (google.com: best guess record for domain of linux-kselftest-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kselftest-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=ibm.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755495AbeASB6X (ORCPT ); Thu, 18 Jan 2018 20:58:23 -0500 Received: from mail-qt0-f195.google.com ([209.85.216.195]:42237 "EHLO mail-qt0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755363AbeASBwM (ORCPT ); Thu, 18 Jan 2018 20:52:12 -0500 From: Ram Pai To: mpe@ellerman.id.au, mingo@redhat.com, akpm@linux-foundation.org, corbet@lwn.net, arnd@arndb.de Cc: linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, x86@kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, dave.hansen@intel.com, benh@kernel.crashing.org, paulus@samba.org, khandual@linux.vnet.ibm.com, aneesh.kumar@linux.vnet.ibm.com, bsingharora@gmail.com, hbabu@us.ibm.com, mhocko@kernel.org, bauerman@linux.vnet.ibm.com, ebiederm@xmission.com, linuxram@us.ibm.com Subject: [PATCH v10 11/27] powerpc: introduce execute-only pkey Date: Thu, 18 Jan 2018 17:50:32 -0800 Message-Id: <1516326648-22775-12-git-send-email-linuxram@us.ibm.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1516326648-22775-1-git-send-email-linuxram@us.ibm.com> References: <1516326648-22775-1-git-send-email-linuxram@us.ibm.com> Sender: linux-kselftest-owner@vger.kernel.org X-Mailing-List: linux-kselftest@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1589984256013531214?= X-GMAIL-MSGID: =?utf-8?q?1589984256013531214?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: This patch provides the implementation of execute-only pkey. The architecture-independent layer expects the arch-dependent layer, to support the ability to create and enable a special key which has execute-only permission. Acked-by: Balbir Singh Signed-off-by: Ram Pai --- arch/powerpc/include/asm/book3s/64/mmu.h | 1 + arch/powerpc/include/asm/pkeys.h | 6 +++- arch/powerpc/mm/pkeys.c | 58 ++++++++++++++++++++++++++++++ 3 files changed, 64 insertions(+), 1 deletions(-) diff --git a/arch/powerpc/include/asm/book3s/64/mmu.h b/arch/powerpc/include/asm/book3s/64/mmu.h index 37ef23c..0abeb0e 100644 --- a/arch/powerpc/include/asm/book3s/64/mmu.h +++ b/arch/powerpc/include/asm/book3s/64/mmu.h @@ -116,6 +116,7 @@ struct patb_entry { * bit unset -> key available for allocation */ u32 pkey_allocation_map; + s16 execute_only_pkey; /* key holding execute-only protection */ #endif } mm_context_t; diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h index 3def5af..2b5bb35 100644 --- a/arch/powerpc/include/asm/pkeys.h +++ b/arch/powerpc/include/asm/pkeys.h @@ -128,9 +128,13 @@ static inline int mm_pkey_free(struct mm_struct *mm, int pkey) * Try to dedicate one of the protection keys to be used as an * execute-only protection key. */ +extern int __execute_only_pkey(struct mm_struct *mm); static inline int execute_only_pkey(struct mm_struct *mm) { - return 0; + if (static_branch_likely(&pkey_disabled)) + return -1; + + return __execute_only_pkey(mm); } static inline int arch_override_mprotect_pkey(struct vm_area_struct *vma, diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c index 7dfcf2d..b466a2c 100644 --- a/arch/powerpc/mm/pkeys.c +++ b/arch/powerpc/mm/pkeys.c @@ -96,6 +96,8 @@ void pkey_mm_init(struct mm_struct *mm) if (static_branch_likely(&pkey_disabled)) return; mm_pkey_allocation_map(mm) = initial_allocation_mask; + /* -1 means unallocated or invalid */ + mm->context.execute_only_pkey = -1; } static inline u64 read_amr(void) @@ -260,3 +262,59 @@ void thread_pkey_regs_init(struct thread_struct *thread) write_iamr(read_iamr() & pkey_iamr_mask); write_uamor(read_uamor() & pkey_amr_uamor_mask); } + +static inline bool pkey_allows_readwrite(int pkey) +{ + int pkey_shift = pkeyshift(pkey); + + if (!is_pkey_enabled(pkey)) + return true; + + return !(read_amr() & ((AMR_RD_BIT|AMR_WR_BIT) << pkey_shift)); +} + +int __execute_only_pkey(struct mm_struct *mm) +{ + bool need_to_set_mm_pkey = false; + int execute_only_pkey = mm->context.execute_only_pkey; + int ret; + + /* Do we need to assign a pkey for mm's execute-only maps? */ + if (execute_only_pkey == -1) { + /* Go allocate one to use, which might fail */ + execute_only_pkey = mm_pkey_alloc(mm); + if (execute_only_pkey < 0) + return -1; + need_to_set_mm_pkey = true; + } + + /* + * We do not want to go through the relatively costly dance to set AMR + * if we do not need to. Check it first and assume that if the + * execute-only pkey is readwrite-disabled than we do not have to set it + * ourselves. + */ + if (!need_to_set_mm_pkey && !pkey_allows_readwrite(execute_only_pkey)) + return execute_only_pkey; + + /* + * Set up AMR so that it denies access for everything other than + * execution. + */ + ret = __arch_set_user_pkey_access(current, execute_only_pkey, + PKEY_DISABLE_ACCESS | + PKEY_DISABLE_WRITE); + /* + * If the AMR-set operation failed somehow, just return 0 and + * effectively disable execute-only support. + */ + if (ret) { + mm_pkey_free(mm, execute_only_pkey); + return -1; + } + + /* We got one, store it and use it from here on out */ + if (need_to_set_mm_pkey) + mm->context.execute_only_pkey = execute_only_pkey; + return execute_only_pkey; +} -- 1.7.1