From fc1221b3a163d1386d1052184202d5dc50d302d1 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Fri, 1 Apr 2016 14:17:26 +0200 Subject: [PATCH] netfilter: x_tables: add compat version of xt_check_entry_offsets 32bit rulesets have different layout and alignment requirements, so once more integrity checks get added to xt_check_entry_offsets it will reject well-formed 32bit rulesets. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- include/linux/netfilter/x_tables.h | 3 +++ net/ipv4/netfilter/arp_tables.c | 3 ++- net/ipv4/netfilter/ip_tables.c | 3 ++- net/ipv6/netfilter/ip6_tables.c | 3 ++- net/netfilter/x_tables.c | 22 ++++++++++++++++++++++ 5 files changed, 31 insertions(+), 3 deletions(-) diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h index 0de0862897a4..08de48bbe92e 100644 --- a/include/linux/netfilter/x_tables.h +++ b/include/linux/netfilter/x_tables.h @@ -494,6 +494,9 @@ void xt_compat_target_from_user(struct xt_entry_target *t, void **dstptr, unsigned int *size); int xt_compat_target_to_user(const struct xt_entry_target *t, void __user **dstptr, unsigned int *size); +int xt_compat_check_entry_offsets(const void *base, + unsigned int target_offset, + unsigned int next_offset); #endif /* CONFIG_COMPAT */ #endif /* _X_TABLES_H */ diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c index 24ad92a60b7a..ab8952a49bfa 100644 --- a/net/ipv4/netfilter/arp_tables.c +++ b/net/ipv4/netfilter/arp_tables.c @@ -1254,7 +1254,8 @@ check_compat_entry_size_and_hooks(struct compat_arpt_entry *e, if (!arp_checkentry(&e->arp)) return -EINVAL; - ret = xt_check_entry_offsets(e, e->target_offset, e->next_offset); + ret = xt_compat_check_entry_offsets(e, e->target_offset, + e->next_offset); if (ret) return ret; diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c index cdf18502a047..7d24c872723f 100644 --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -1513,7 +1513,8 @@ check_compat_entry_size_and_hooks(struct compat_ipt_entry *e, if (!ip_checkentry(&e->ip)) return -EINVAL; - ret = xt_check_entry_offsets(e, e->target_offset, e->next_offset); + ret = xt_compat_check_entry_offsets(e, + e->target_offset, e->next_offset); if (ret) return ret; diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c index e3783116ed48..73eee7b5fd60 100644 --- a/net/ipv6/netfilter/ip6_tables.c +++ b/net/ipv6/netfilter/ip6_tables.c @@ -1525,7 +1525,8 @@ check_compat_entry_size_and_hooks(struct compat_ip6t_entry *e, if (!ip6_checkentry(&e->ipv6)) return -EINVAL; - ret = xt_check_entry_offsets(e, e->target_offset, e->next_offset); + ret = xt_compat_check_entry_offsets(e, + e->target_offset, e->next_offset); if (ret) return ret; diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c index ec1b7183fff9..fa206ceb269f 100644 --- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -539,6 +539,27 @@ int xt_compat_match_to_user(const struct xt_entry_match *m, return 0; } EXPORT_SYMBOL_GPL(xt_compat_match_to_user); + +int xt_compat_check_entry_offsets(const void *base, + unsigned int target_offset, + unsigned int next_offset) +{ + const struct compat_xt_entry_target *t; + const char *e = base; + + if (target_offset + sizeof(*t) > next_offset) + return -EINVAL; + + t = (void *)(e + target_offset); + if (t->u.target_size < sizeof(*t)) + return -EINVAL; + + if (target_offset + t->u.target_size > next_offset) + return -EINVAL; + + return 0; +} +EXPORT_SYMBOL(xt_compat_check_entry_offsets); #endif /* CONFIG_COMPAT */ /** @@ -549,6 +570,7 @@ EXPORT_SYMBOL_GPL(xt_compat_match_to_user); * @next_offset: the arp/ip/ip6_t->next_offset * * validates that target_offset and next_offset are sane. + * Also see xt_compat_check_entry_offsets for CONFIG_COMPAT version. * * The arp/ip/ip6t_entry structure @base must have passed following tests: * - it must point to a valid memory location -- 2.20.1