From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,T_MIXED_ES,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2C21FC65BAF for ; Wed, 12 Dec 2018 15:22:42 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E086D2080F for ; Wed, 12 Dec 2018 15:22:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="udOsckwb" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E086D2080F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=wATmUg75pQjOXqfFdCVhnk9vr5npbg5wbtSvwjDPpsM=; b=udOsckwbxiwh04 OUWEtw35SWjpA3ZHirk8+KXzph1/zq26rZjwt1YGV9iF4+2OhyuNtLtxouAEtemqHl5jka/vdzOaW eVVEJMhQkbA4fLqUKUnpXPSeC4HsG+1TKq2srpAKQBF2L4hX305bsnLR25gcvKuO9QPEErUa3JDB/ 32BZBjf0kr6jOPj4YDTFBimExjGdyUG4AXdVY4hn0LwLjJgDLNnxLQkyjTTnp23eGCiipOQIowIO0 flHMpRVKLzDFi23v8bZuGb0Gp63qBPu0XZWmn2ps+NcWFPVX1BpSIeKeQPdTM/N13dxf+tUceu4sz xJMfkaWgrVJXByiXW5oA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gX6LK-0000Wd-20; Wed, 12 Dec 2018 15:22:34 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gX6LF-0000Vi-SC for linux-arm-kernel@lists.infradead.org; Wed, 12 Dec 2018 15:22:31 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6CD9780D; Wed, 12 Dec 2018 07:22:19 -0800 (PST) Received: from e103592.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E2D493F575; Wed, 12 Dec 2018 07:22:16 -0800 (PST) Date: Wed, 12 Dec 2018 15:22:14 +0000 From: Dave Martin To: Kristina Martsenko Subject: Re: [PATCH v6 10/13] arm64: add prctl control for resetting ptrauth keys Message-ID: <20181212152214.GX3505@e103592.cambridge.arm.com> References: <20181207183931.4285-1-kristina.martsenko@arm.com> <20181207183931.4285-11-kristina.martsenko@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20181207183931.4285-11-kristina.martsenko@arm.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20181212_072229_922366_72050951 X-CRM114-Status: GOOD ( 25.71 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jacob Bramley , Ard Biesheuvel , Marc Zyngier , Catalin Marinas , Adam Wallis , Richard Henderson , linux-kernel@vger.kernel.org, Will Deacon , Cyrill Gorcunov , Ramana Radhakrishnan , Amit Kachhap , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, Kees Cook Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Dec 07, 2018 at 06:39:28PM +0000, Kristina Martsenko wrote: > Add an arm64-specific prctl to allow a thread to reinitialize its > pointer authentication keys to random values. This can be useful when > exec() is not used for starting new processes, to ensure that different > processes still have different keys. > > Signed-off-by: Kristina Martsenko > --- > arch/arm64/include/asm/pointer_auth.h | 3 +++ > arch/arm64/include/asm/processor.h | 4 +++ > arch/arm64/kernel/Makefile | 1 + > arch/arm64/kernel/pointer_auth.c | 47 +++++++++++++++++++++++++++++++++++ > include/uapi/linux/prctl.h | 8 ++++++ > kernel/sys.c | 8 ++++++ > 6 files changed, 71 insertions(+) > create mode 100644 arch/arm64/kernel/pointer_auth.c > > diff --git a/arch/arm64/include/asm/pointer_auth.h b/arch/arm64/include/asm/pointer_auth.h > index 89190d93c850..7797bc346c6b 100644 > --- a/arch/arm64/include/asm/pointer_auth.h > +++ b/arch/arm64/include/asm/pointer_auth.h > @@ -59,6 +59,8 @@ static inline void ptrauth_keys_switch(struct ptrauth_keys *keys) > __ptrauth_key_install(APGA, keys->apga); > } > > +extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg); > + > /* > * The EL0 pointer bits used by a pointer authentication code. > * This is dependent on TBI0 being enabled, or bits 63:56 would also apply. > @@ -82,6 +84,7 @@ do { \ > ptrauth_keys_switch(&(tsk)->thread_info.keys_user) > > #else /* CONFIG_ARM64_PTR_AUTH */ > +#define ptrauth_prctl_reset_keys(tsk, arg) (-EINVAL) > #define ptrauth_strip_insn_pac(lr) (lr) > #define ptrauth_thread_init_user(tsk) > #define ptrauth_thread_switch(tsk) > diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h > index 6b0d4dff5012..40ccfb7605b6 100644 > --- a/arch/arm64/include/asm/processor.h > +++ b/arch/arm64/include/asm/processor.h > @@ -46,6 +46,7 @@ > #include > #include > #include > +#include > #include > #include > > @@ -270,6 +271,9 @@ extern void __init minsigstksz_setup(void); > #define SVE_SET_VL(arg) sve_set_current_vl(arg) > #define SVE_GET_VL() sve_get_current_vl() > > +/* PR_PAC_RESET_KEYS prctl */ > +#define PAC_RESET_KEYS(tsk, arg) ptrauth_prctl_reset_keys(tsk, arg) > + > /* > * For CONFIG_GCC_PLUGIN_STACKLEAK > * > diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile > index 4c8b13bede80..096740ab81d2 100644 > --- a/arch/arm64/kernel/Makefile > +++ b/arch/arm64/kernel/Makefile > @@ -57,6 +57,7 @@ arm64-obj-$(CONFIG_CRASH_DUMP) += crash_dump.o > arm64-obj-$(CONFIG_CRASH_CORE) += crash_core.o > arm64-obj-$(CONFIG_ARM_SDE_INTERFACE) += sdei.o > arm64-obj-$(CONFIG_ARM64_SSBD) += ssbd.o > +arm64-obj-$(CONFIG_ARM64_PTR_AUTH) += pointer_auth.o > > obj-y += $(arm64-obj-y) vdso/ probes/ > obj-m += $(arm64-obj-m) > diff --git a/arch/arm64/kernel/pointer_auth.c b/arch/arm64/kernel/pointer_auth.c > new file mode 100644 > index 000000000000..b9f6f5f3409a > --- /dev/null > +++ b/arch/arm64/kernel/pointer_auth.c > @@ -0,0 +1,47 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +#include > +#include > +#include > +#include > +#include > +#include > + > +int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg) > +{ > + struct ptrauth_keys *keys = &tsk->thread_info.keys_user; > + unsigned long addr_key_mask = PR_PAC_APIAKEY | PR_PAC_APIBKEY | > + PR_PAC_APDAKEY | PR_PAC_APDBKEY; > + unsigned long key_mask = addr_key_mask | PR_PAC_APGAKEY; > + > + if (!system_supports_address_auth() && !system_supports_generic_auth()) > + return -EINVAL; > + > + if (!arg) { > + ptrauth_keys_init(keys); > + ptrauth_keys_switch(keys); > + return 0; > + } > + > + if (arg & ~key_mask) > + return -EINVAL; > + > + if (((arg & addr_key_mask) && !system_supports_address_auth()) || > + ((arg & PR_PAC_APGAKEY) && !system_supports_generic_auth())) > + return -EINVAL; > + > + if (arg & PR_PAC_APIAKEY) > + get_random_bytes(&keys->apia, sizeof(keys->apia)); > + if (arg & PR_PAC_APIBKEY) > + get_random_bytes(&keys->apib, sizeof(keys->apib)); > + if (arg & PR_PAC_APDAKEY) > + get_random_bytes(&keys->apda, sizeof(keys->apda)); > + if (arg & PR_PAC_APDBKEY) > + get_random_bytes(&keys->apdb, sizeof(keys->apdb)); > + if (arg & PR_PAC_APGAKEY) > + get_random_bytes(&keys->apga, sizeof(keys->apga)); > + > + ptrauth_keys_switch(keys); > + > + return 0; > +} > diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h > index b17201edfa09..b4875a93363a 100644 > --- a/include/uapi/linux/prctl.h > +++ b/include/uapi/linux/prctl.h > @@ -220,4 +220,12 @@ struct prctl_mm_map { > # define PR_SPEC_DISABLE (1UL << 2) > # define PR_SPEC_FORCE_DISABLE (1UL << 3) > > +/* Reset arm64 pointer authentication keys */ > +#define PR_PAC_RESET_KEYS 54 > +# define PR_PAC_APIAKEY (1UL << 0) > +# define PR_PAC_APIBKEY (1UL << 1) > +# define PR_PAC_APDAKEY (1UL << 2) > +# define PR_PAC_APDBKEY (1UL << 3) > +# define PR_PAC_APGAKEY (1UL << 4) > + > #endif /* _LINUX_PRCTL_H */ > diff --git a/kernel/sys.c b/kernel/sys.c > index 123bd73046ec..64b5a230f38d 100644 > --- a/kernel/sys.c > +++ b/kernel/sys.c > @@ -121,6 +121,9 @@ > #ifndef SVE_GET_VL > # define SVE_GET_VL() (-EINVAL) > #endif > +#ifndef PAC_RESET_KEYS > +# define PAC_RESET_KEYS(a, b) (-EINVAL) > +#endif > > /* > * this is where the system-wide overflow UID and GID are defined, for > @@ -2476,6 +2479,11 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, > return -EINVAL; > error = arch_prctl_spec_ctrl_set(me, arg2, arg3); > break; > + case PR_PAC_RESET_KEYS: > + if (arg3 || arg4 || arg5) > + return -EINVAL; > + error = PAC_RESET_KEYS(me, arg2); > + break; If this only ever operated on current, can we drop the task argument? (Last time I looked, the task argument is useless for all existing prctls -- I have some outstanding refactoring to get rid of it entirely.) Since arg2 contains unused flag bits and we already return -EINVAL if any of those are set, we can define a new flag in arg2 in the future if we want to extend this interface. So I think we can drop the checks on arg3..arg5 and avoid the need for the caller to supply , 0, 0, 0) in every call to this prctl. (But if someone else objects to this approach I'm happy to concede on this point). Cheers ---Dave _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel