Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932853AbdC2SS2 (ORCPT ); Wed, 29 Mar 2017 14:18:28 -0400 Received: from mail-pg0-f47.google.com ([74.125.83.47]:34461 "EHLO mail-pg0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932476AbdC2SQ0 (ORCPT ); Wed, 29 Mar 2017 14:16:26 -0400 From: Kees Cook To: kernel-hardening@lists.openwall.com Cc: Kees Cook , Mark Rutland , Andy Lutomirski , Hoeun Ryu , PaX Team , Emese Revfy , Russell King , x86@kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [RFC v2][PATCH 09/11] list: add rare_write() list helpers Date: Wed, 29 Mar 2017 11:16:01 -0700 Message-Id: <1490811363-93944-10-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1490811363-93944-1-git-send-email-keescook@chromium.org> References: <1490811363-93944-1-git-send-email-keescook@chromium.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3322 Lines: 110 Some structures that are intended to be made write-rarely are designed to be linked by lists. As a result, there need to be rare_write()-supported linked list primitives. As found in PaX, this adds list management helpers for doing updates to rarely-changed lists. Signed-off-by: Kees Cook --- include/linux/list.h | 17 +++++++++++++++++ lib/Makefile | 2 +- lib/list_debug.c | 37 +++++++++++++++++++++++++++++++++++++ 3 files changed, 55 insertions(+), 1 deletion(-) diff --git a/include/linux/list.h b/include/linux/list.h index ae537fa46216..50fdd5b737aa 100644 --- a/include/linux/list.h +++ b/include/linux/list.h @@ -126,6 +126,23 @@ static inline void list_del(struct list_head *entry) entry->prev = LIST_POISON2; } +extern void __rare_list_add(struct list_head *new, + struct list_head *prev, + struct list_head *next); + +static inline void +rare_list_add(__wr_rare_type struct list_head *new, struct list_head *head) +{ + __rare_list_add((struct list_head *)new, head, head->next); +} +static inline void +rare_list_add_tail(__wr_rare_type struct list_head *new, struct list_head *head) +{ + __rare_list_add((struct list_head *)new, head->prev, head); +} + +extern void rare_list_del(__wr_rare_type struct list_head *entry); + /** * list_replace - replace old entry by new one * @old : the element to be replaced diff --git a/lib/Makefile b/lib/Makefile index 320ac46a8725..cd64fd8f7a21 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -83,7 +83,7 @@ obj-$(CONFIG_BTREE) += btree.o obj-$(CONFIG_INTERVAL_TREE) += interval_tree.o obj-$(CONFIG_ASSOCIATIVE_ARRAY) += assoc_array.o obj-$(CONFIG_DEBUG_PREEMPT) += smp_processor_id.o -obj-$(CONFIG_DEBUG_LIST) += list_debug.o +obj-y += list_debug.o obj-$(CONFIG_DEBUG_OBJECTS) += debugobjects.o ifneq ($(CONFIG_HAVE_DEC_LOCK),y) diff --git a/lib/list_debug.c b/lib/list_debug.c index a34db8d27667..1add73f9479a 100644 --- a/lib/list_debug.c +++ b/lib/list_debug.c @@ -10,7 +10,9 @@ #include #include #include +#include +#ifdef CONFIG_DEBUG_LIST /* * Check that the data structures for the list manipulations are reasonably * valid. Failures here indicate memory corruption (and possibly an exploit @@ -60,3 +62,38 @@ bool __list_del_entry_valid(struct list_head *entry) } EXPORT_SYMBOL(__list_del_entry_valid); + +#endif /* CONFIG_DEBUG_LIST */ + +void __rare_list_add(struct list_head *new, struct list_head *prev, + struct list_head *next) +{ + if (!__list_add_valid(new, prev, next)) + return; + + rare_write_begin(); + __rare_write(next->prev, new); + __rare_write(new->next, next); + __rare_write(new->prev, prev); + __rare_write(prev->next, new); + rare_write_end(); +} +EXPORT_SYMBOL(__rare_list_add); + +void rare_list_del(__wr_rare_type struct list_head *entry_const) +{ + struct list_head *entry = (struct list_head *)entry_const; + struct list_head *prev = entry->prev; + struct list_head *next = entry->next; + + if (!__list_del_entry_valid(entry)) + return; + + rare_write_begin(); + __rare_write(next->prev, prev); + __rare_write(prev->next, next); + __rare_write(entry->next, LIST_POISON1); + __rare_write(entry->prev, LIST_POISON2); + rare_write_end(); +} +EXPORT_SYMBOL(rare_list_del); -- 2.7.4