From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752558AbcFVWp1 (ORCPT ); Wed, 22 Jun 2016 18:45:27 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:46245 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752454AbcFVWmB (ORCPT ); Wed, 22 Jun 2016 18:42:01 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Florian Westphal , Pablo Neira Ayuso Subject: [PATCH 4.4 68/75] netfilter: x_tables: add and use xt_check_entry_offsets Date: Wed, 22 Jun 2016 15:41:30 -0700 Message-Id: <20160622223503.423684755@linuxfoundation.org> X-Mailer: git-send-email 2.9.0 In-Reply-To: <20160622223500.055133765@linuxfoundation.org> References: <20160622223500.055133765@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Florian Westphal commit 7d35812c3214afa5b37a675113555259cfd67b98 upstream. Currently arp/ip and ip6tables each implement a short helper to check that the target offset is large enough to hold one xt_entry_target struct and that t->u.target_size fits within the current rule. Unfortunately these checks are not sufficient. To avoid adding new tests to all of ip/ip6/arptables move the current checks into a helper, then extend this helper in followup patches. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Greg Kroah-Hartman --- include/linux/netfilter/x_tables.h | 4 ++++ net/ipv4/netfilter/arp_tables.c | 11 +---------- net/ipv4/netfilter/ip_tables.c | 12 +----------- net/ipv6/netfilter/ip6_tables.c | 12 +----------- net/netfilter/x_tables.c | 34 ++++++++++++++++++++++++++++++++++ 5 files changed, 41 insertions(+), 32 deletions(-) --- a/include/linux/netfilter/x_tables.h +++ b/include/linux/netfilter/x_tables.h @@ -239,6 +239,10 @@ void xt_unregister_match(struct xt_match int xt_register_matches(struct xt_match *match, unsigned int n); void xt_unregister_matches(struct xt_match *match, unsigned int n); +int xt_check_entry_offsets(const void *base, + unsigned int target_offset, + unsigned int next_offset); + int xt_check_match(struct xt_mtchk_param *, unsigned int size, u_int8_t proto, bool inv_proto); int xt_check_target(struct xt_tgchk_param *, unsigned int size, u_int8_t proto, --- a/net/ipv4/netfilter/arp_tables.c +++ b/net/ipv4/netfilter/arp_tables.c @@ -496,19 +496,10 @@ next: static inline int check_entry(const struct arpt_entry *e) { - const struct xt_entry_target *t; - if (!arp_checkentry(&e->arp)) return -EINVAL; - if (e->target_offset + sizeof(struct xt_entry_target) > e->next_offset) - return -EINVAL; - - t = arpt_get_target_c(e); - if (e->target_offset + t->u.target_size > e->next_offset) - return -EINVAL; - - return 0; + return xt_check_entry_offsets(e, e->target_offset, e->next_offset); } static inline int check_target(struct arpt_entry *e, const char *name) --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -590,20 +590,10 @@ static void cleanup_match(struct xt_entr static int check_entry(const struct ipt_entry *e) { - const struct xt_entry_target *t; - if (!ip_checkentry(&e->ip)) return -EINVAL; - if (e->target_offset + sizeof(struct xt_entry_target) > - e->next_offset) - return -EINVAL; - - t = ipt_get_target_c(e); - if (e->target_offset + t->u.target_size > e->next_offset) - return -EINVAL; - - return 0; + return xt_check_entry_offsets(e, e->target_offset, e->next_offset); } static int --- a/net/ipv6/netfilter/ip6_tables.c +++ b/net/ipv6/netfilter/ip6_tables.c @@ -602,20 +602,10 @@ static void cleanup_match(struct xt_entr static int check_entry(const struct ip6t_entry *e) { - const struct xt_entry_target *t; - if (!ip6_checkentry(&e->ipv6)) return -EINVAL; - if (e->target_offset + sizeof(struct xt_entry_target) > - e->next_offset) - return -EINVAL; - - t = ip6t_get_target_c(e); - if (e->target_offset + t->u.target_size > e->next_offset) - return -EINVAL; - - return 0; + return xt_check_entry_offsets(e, e->target_offset, e->next_offset); } static int check_match(struct xt_entry_match *m, struct xt_mtchk_param *par) --- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -540,6 +540,40 @@ int xt_compat_match_to_user(const struct EXPORT_SYMBOL_GPL(xt_compat_match_to_user); #endif /* CONFIG_COMPAT */ +/** + * xt_check_entry_offsets - validate arp/ip/ip6t_entry + * + * @base: pointer to arp/ip/ip6t_entry + * @target_offset: the arp/ip/ip6_t->target_offset + * @next_offset: the arp/ip/ip6_t->next_offset + * + * validates that target_offset and next_offset are sane. + * + * The arp/ip/ip6t_entry structure @base must have passed following tests: + * - it must point to a valid memory location + * - base to base + next_offset must be accessible, i.e. not exceed allocated + * length. + * + * Return: 0 on success, negative errno on failure. + */ +int xt_check_entry_offsets(const void *base, + unsigned int target_offset, + unsigned int next_offset) +{ + const struct xt_entry_target *t; + const char *e = base; + + if (target_offset + sizeof(*t) > next_offset) + return -EINVAL; + + t = (void *)(e + target_offset); + if (target_offset + t->u.target_size > next_offset) + return -EINVAL; + + return 0; +} +EXPORT_SYMBOL(xt_check_entry_offsets); + int xt_check_target(struct xt_tgchk_param *par, unsigned int size, u_int8_t proto, bool inv_proto) {