From: Dan Williams <dan.j.williams@intel.com> To: linux-kernel@vger.kernel.org Cc: linux-arch@vger.kernel.org, kernel-hardening@lists.openwall.com, Catalin Marinas <catalin.marinas@arm.com>, x86@kernel.org, Will Deacon <will.deacon@arm.com>, Russell King <linux@armlinux.org.uk>, Ingo Molnar <mingo@redhat.com>, gregkh@linuxfoundation.org, "H. Peter Anvin" <hpa@zytor.com>, tglx@linutronix.de, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@linux.intel.com Subject: [PATCH v4 02/10] asm/nospec, array_ptr: sanitize speculative array de-references Date: Thu, 18 Jan 2018 16:01:46 -0800 [thread overview] Message-ID: <151632010687.21271.12004432287640499992.stgit@dwillia2-desk3.amr.corp.intel.com> (raw) In-Reply-To: <151632009605.21271.11304291057104672116.stgit@dwillia2-desk3.amr.corp.intel.com> 'array_ptr' is proposed as a generic mechanism to mitigate against Spectre-variant-1 attacks, i.e. an attack that bypasses boundary checks via speculative execution). The 'array_ptr' implementation is expected to be safe for current generation cpus across multiple architectures (ARM, x86). Based on an original implementation by Linus Torvalds, tweaked to remove speculative flows by Alexei Starovoitov, and tweaked again by Linus to introduce an x86 assembly implementation for the mask generation. Co-developed-by: Linus Torvalds <torvalds@linux-foundation.org> Co-developed-by: Alexei Starovoitov <ast@kernel.org> Co-developed-by: Peter Zijlstra <peterz@infradead.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: x86@kernel.org Signed-off-by: Dan Williams <dan.j.williams@intel.com> --- include/linux/nospec.h | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) create mode 100644 include/linux/nospec.h diff --git a/include/linux/nospec.h b/include/linux/nospec.h new file mode 100644 index 000000000000..f841c11f3f1f --- /dev/null +++ b/include/linux/nospec.h @@ -0,0 +1,44 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright(c) 2018 Intel Corporation. All rights reserved. + +#ifndef __NOSPEC_H__ +#define __NOSPEC_H__ + +#include <linux/jump_label.h> +#include <asm/barrier.h> + +/* + * If idx is negative or if idx > size then bit 63 is set in the mask, + * and the value of ~(-1L) is zero. When the mask is zero, bounds check + * failed, array_ptr will return NULL. + */ +#ifndef array_ptr_mask +static inline unsigned long array_ptr_mask(unsigned long idx, unsigned long sz) +{ + return ~(long)(idx | (sz - 1 - idx)) >> (BITS_PER_LONG - 1); +} +#endif + +/** + * array_ptr - Generate a pointer to an array element, ensuring + * the pointer is bounded under speculation to NULL. + * + * @base: the base of the array + * @idx: the index of the element, must be less than LONG_MAX + * @sz: the number of elements in the array, must be less than LONG_MAX + * + * If @idx falls in the interval [0, @sz), returns the pointer to + * @arr[@idx], otherwise returns NULL. + */ +#define array_ptr(base, idx, sz) \ +({ \ + union { typeof(*(base)) *_ptr; unsigned long _bit; } __u; \ + typeof(*(base)) *_arr = (base); \ + unsigned long _i = (idx); \ + unsigned long _mask = array_ptr_mask(_i, (sz)); \ + \ + __u._ptr = _arr + (_i & _mask); \ + __u._bit &= _mask; \ + __u._ptr; \ +}) +#endif /* __NOSPEC_H__ */
WARNING: multiple messages have this Message-ID (diff)
From: Dan Williams <dan.j.williams@intel.com> To: linux-kernel@vger.kernel.org Cc: linux-arch@vger.kernel.org, kernel-hardening@lists.openwall.com, Catalin Marinas <catalin.marinas@arm.com>, x86@kernel.org, Will Deacon <will.deacon@arm.com>, Russell King <linux@armlinux.org.uk>, Ingo Molnar <mingo@redhat.com>, gregkh@linuxfoundation.org, "H. Peter Anvin" <hpa@zytor.com>, tglx@linutronix.de, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@linux.intel.com Subject: [kernel-hardening] [PATCH v4 02/10] asm/nospec, array_ptr: sanitize speculative array de-references Date: Thu, 18 Jan 2018 16:01:46 -0800 [thread overview] Message-ID: <151632010687.21271.12004432287640499992.stgit@dwillia2-desk3.amr.corp.intel.com> (raw) In-Reply-To: <151632009605.21271.11304291057104672116.stgit@dwillia2-desk3.amr.corp.intel.com> 'array_ptr' is proposed as a generic mechanism to mitigate against Spectre-variant-1 attacks, i.e. an attack that bypasses boundary checks via speculative execution). The 'array_ptr' implementation is expected to be safe for current generation cpus across multiple architectures (ARM, x86). Based on an original implementation by Linus Torvalds, tweaked to remove speculative flows by Alexei Starovoitov, and tweaked again by Linus to introduce an x86 assembly implementation for the mask generation. Co-developed-by: Linus Torvalds <torvalds@linux-foundation.org> Co-developed-by: Alexei Starovoitov <ast@kernel.org> Co-developed-by: Peter Zijlstra <peterz@infradead.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: x86@kernel.org Signed-off-by: Dan Williams <dan.j.williams@intel.com> --- include/linux/nospec.h | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) create mode 100644 include/linux/nospec.h diff --git a/include/linux/nospec.h b/include/linux/nospec.h new file mode 100644 index 000000000000..f841c11f3f1f --- /dev/null +++ b/include/linux/nospec.h @@ -0,0 +1,44 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright(c) 2018 Intel Corporation. All rights reserved. + +#ifndef __NOSPEC_H__ +#define __NOSPEC_H__ + +#include <linux/jump_label.h> +#include <asm/barrier.h> + +/* + * If idx is negative or if idx > size then bit 63 is set in the mask, + * and the value of ~(-1L) is zero. When the mask is zero, bounds check + * failed, array_ptr will return NULL. + */ +#ifndef array_ptr_mask +static inline unsigned long array_ptr_mask(unsigned long idx, unsigned long sz) +{ + return ~(long)(idx | (sz - 1 - idx)) >> (BITS_PER_LONG - 1); +} +#endif + +/** + * array_ptr - Generate a pointer to an array element, ensuring + * the pointer is bounded under speculation to NULL. + * + * @base: the base of the array + * @idx: the index of the element, must be less than LONG_MAX + * @sz: the number of elements in the array, must be less than LONG_MAX + * + * If @idx falls in the interval [0, @sz), returns the pointer to + * @arr[@idx], otherwise returns NULL. + */ +#define array_ptr(base, idx, sz) \ +({ \ + union { typeof(*(base)) *_ptr; unsigned long _bit; } __u; \ + typeof(*(base)) *_arr = (base); \ + unsigned long _i = (idx); \ + unsigned long _mask = array_ptr_mask(_i, (sz)); \ + \ + __u._ptr = _arr + (_i & _mask); \ + __u._bit &= _mask; \ + __u._ptr; \ +}) +#endif /* __NOSPEC_H__ */
next prev parent reply other threads:[~2018-01-19 0:01 UTC|newest] Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-01-19 0:01 [PATCH v4 00/10] prevent bounds-check bypass via speculative execution Dan Williams 2018-01-19 0:01 ` [kernel-hardening] " Dan Williams 2018-01-19 0:01 ` Dan Williams 2018-01-19 0:01 ` [PATCH v4 01/10] Documentation: document array_ptr Dan Williams 2018-01-19 0:01 ` [kernel-hardening] " Dan Williams 2018-01-19 0:01 ` Dan Williams [this message] 2018-01-19 0:01 ` [kernel-hardening] [PATCH v4 02/10] asm/nospec, array_ptr: sanitize speculative array de-references Dan Williams 2018-01-19 10:20 ` Jann Horn 2018-01-19 17:48 ` Adam Sampson 2018-01-19 17:48 ` Adam Sampson 2018-01-19 17:48 ` Adam Sampson 2018-01-19 17:48 ` Adam Sampson 2018-01-19 18:12 ` Dan Williams 2018-01-19 18:18 ` Will Deacon 2018-01-19 18:18 ` Will Deacon 2018-01-19 18:26 ` [kernel-hardening] " Dan Williams 2018-01-19 18:18 ` Linus Torvalds 2018-01-19 18:18 ` Linus Torvalds 2018-01-19 20:55 ` [kernel-hardening] " Dan Williams 2018-01-25 7:09 ` Cyril Novikov 2018-01-25 7:09 ` [kernel-hardening] " Cyril Novikov 2018-01-25 22:37 ` Dan Williams 2018-01-25 22:37 ` [kernel-hardening] " Dan Williams 2018-01-19 0:01 ` [PATCH v4 03/10] x86: implement array_ptr_mask() Dan Williams 2018-01-19 0:01 ` [kernel-hardening] " Dan Williams 2018-01-19 0:01 ` [PATCH v4 04/10] x86: introduce __uaccess_begin_nospec and ifence Dan Williams 2018-01-19 0:01 ` [kernel-hardening] " Dan Williams 2018-01-19 0:02 ` [PATCH v4 05/10] x86, __get_user: use __uaccess_begin_nospec Dan Williams 2018-01-19 0:02 ` [kernel-hardening] " Dan Williams 2018-01-19 0:02 ` [PATCH v4 06/10] x86, get_user: use pointer masking to limit speculation Dan Williams 2018-01-19 0:02 ` [kernel-hardening] " Dan Williams 2018-01-19 0:02 ` [PATCH v4 07/10] x86: narrow out of bounds syscalls to sys_read under speculation Dan Williams 2018-01-19 0:02 ` [kernel-hardening] " Dan Williams 2018-01-24 14:40 ` Jiri Slaby 2018-01-24 14:40 ` [kernel-hardening] " Jiri Slaby 2018-02-06 19:29 ` Luis Henriques 2018-02-06 19:48 ` Dan Williams 2018-02-06 20:26 ` Linus Torvalds 2018-02-06 20:37 ` Dan Williams 2018-02-06 20:42 ` Linus Torvalds 2018-02-06 20:43 ` Linus Torvalds 2018-02-06 20:49 ` Andy Lutomirski 2018-02-06 20:58 ` Linus Torvalds 2018-02-06 21:37 ` Dan Williams 2018-02-06 22:52 ` Linus Torvalds 2018-02-07 0:33 ` Dan Williams 2018-02-07 1:23 ` Linus Torvalds 2018-02-06 22:51 ` Luis Henriques 2018-02-06 22:51 ` Luis Henriques 2018-01-19 0:02 ` [PATCH v4 08/10] vfs, fdtable: prevent bounds-check bypass via speculative execution Dan Williams 2018-01-19 0:02 ` [kernel-hardening] " Dan Williams 2018-01-19 0:02 ` [PATCH v4 09/10] kvm, x86: fix spectre-v1 mitigation Dan Williams 2018-01-19 0:02 ` [kernel-hardening] " Dan Williams 2018-01-19 8:42 ` Paolo Bonzini 2018-01-19 8:42 ` [kernel-hardening] " Paolo Bonzini 2018-01-19 0:02 ` [PATCH v4 10/10] nl80211: sanitize array index in parse_txq_params Dan Williams 2018-01-19 0:02 ` [kernel-hardening] " Dan Williams 2018-01-19 0:02 ` Dan Williams 2018-01-21 10:37 ` Johannes Berg 2018-01-21 10:37 ` [kernel-hardening] " Johannes Berg 2018-01-21 10:37 ` Johannes Berg 2018-01-20 6:58 ` [PATCH v4 00/10] prevent bounds-check bypass via speculative execution Dan Williams 2018-01-20 6:58 ` [kernel-hardening] " Dan Williams 2018-01-20 6:58 ` Dan Williams 2018-01-20 16:56 ` Alexei Starovoitov 2018-01-20 16:56 ` [kernel-hardening] " Alexei Starovoitov 2018-01-20 16:56 ` Alexei Starovoitov 2018-01-20 17:07 ` Alexei Starovoitov 2018-01-20 17:07 ` [kernel-hardening] " Alexei Starovoitov 2018-01-20 17:07 ` Alexei Starovoitov
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=151632010687.21271.12004432287640499992.stgit@dwillia2-desk3.amr.corp.intel.com \ --to=dan.j.williams@intel.com \ --cc=akpm@linux-foundation.org \ --cc=alan@linux.intel.com \ --cc=catalin.marinas@arm.com \ --cc=gregkh@linuxfoundation.org \ --cc=hpa@zytor.com \ --cc=kernel-hardening@lists.openwall.com \ --cc=linux-arch@vger.kernel.org \ --cc=linux-kernel@vger.kernel.org \ --cc=linux@armlinux.org.uk \ --cc=mingo@redhat.com \ --cc=tglx@linutronix.de \ --cc=torvalds@linux-foundation.org \ --cc=will.deacon@arm.com \ --cc=x86@kernel.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.