From 569ccae68b38654f04b6842b034aa33857f605fe Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Tue, 10 Apr 2018 09:30:27 +0200 Subject: netfilter: nf_tables: can't fail after linking rule into active rule list rules in nftables a free'd using kfree, but protected by rcu, i.e. we must wait for a grace period to elapse. Normal removal patch does this, but nf_tables_newrule() doesn't obey this rule during error handling. It calls nft_trans_rule_add() *after* linking rule, and, if that fails to allocate memory, it unlinks the rule and then kfree() it -- this is unsafe. Switch order -- first add rule to transaction list, THEN link it to public list. Note: nft_trans_rule_add() uses GFP_KERNEL; it will not fail so this is not a problem in practice (spotted only during code review). Fixes: 0628b123c96d12 ("netfilter: nfnetlink: add batch support and use it from nf_tables") Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 59 +++++++++++++++++++++++-------------------- 1 file changed, 32 insertions(+), 27 deletions(-) (limited to 'net/netfilter/nf_tables_api.c') diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 9134cc429ad4..b1984f8f7253 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -2361,41 +2361,46 @@ static int nf_tables_newrule(struct net *net, struct sock *nlsk, } if (nlh->nlmsg_flags & NLM_F_REPLACE) { - if (nft_is_active_next(net, old_rule)) { - trans = nft_trans_rule_add(&ctx, NFT_MSG_DELRULE, - old_rule); - if (trans == NULL) { - err = -ENOMEM; - goto err2; - } - nft_deactivate_next(net, old_rule); - chain->use--; - list_add_tail_rcu(&rule->list, &old_rule->list); - } else { + if (!nft_is_active_next(net, old_rule)) { err = -ENOENT; goto err2; } - } else if (nlh->nlmsg_flags & NLM_F_APPEND) - if (old_rule) - list_add_rcu(&rule->list, &old_rule->list); - else - list_add_tail_rcu(&rule->list, &chain->rules); - else { - if (old_rule) - list_add_tail_rcu(&rule->list, &old_rule->list); - else - list_add_rcu(&rule->list, &chain->rules); - } + trans = nft_trans_rule_add(&ctx, NFT_MSG_DELRULE, + old_rule); + if (trans == NULL) { + err = -ENOMEM; + goto err2; + } + nft_deactivate_next(net, old_rule); + chain->use--; - if (nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule) == NULL) { - err = -ENOMEM; - goto err3; + if (nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule) == NULL) { + err = -ENOMEM; + goto err2; + } + + list_add_tail_rcu(&rule->list, &old_rule->list); + } else { + if (nft_trans_rule_add(&ctx, NFT_MSG_NEWRULE, rule) == NULL) { + err = -ENOMEM; + goto err2; + } + + if (nlh->nlmsg_flags & NLM_F_APPEND) { + if (old_rule) + list_add_rcu(&rule->list, &old_rule->list); + else + list_add_tail_rcu(&rule->list, &chain->rules); + } else { + if (old_rule) + list_add_tail_rcu(&rule->list, &old_rule->list); + else + list_add_rcu(&rule->list, &chain->rules); + } } chain->use++; return 0; -err3: - list_del_rcu(&rule->list); err2: nf_tables_rule_destroy(&ctx, rule); err1: -- cgit v1.2.1 From 2f6adf481527c8ab8033c601f55bfb5b3712b2ac Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Tue, 10 Apr 2018 09:00:24 +0200 Subject: netfilter: nf_tables: free set name in error path set->name must be free'd here in case ops->init fails. Fixes: 387454901bd6 ("netfilter: nf_tables: Allow set names of up to 255 chars") Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'net/netfilter/nf_tables_api.c') diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index b1984f8f7253..102ad873acb4 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -3212,18 +3212,20 @@ static int nf_tables_newset(struct net *net, struct sock *nlsk, err = ops->init(set, &desc, nla); if (err < 0) - goto err2; + goto err3; err = nft_trans_set_add(&ctx, NFT_MSG_NEWSET, set); if (err < 0) - goto err3; + goto err4; list_add_tail_rcu(&set->list, &table->sets); table->use++; return 0; -err3: +err4: ops->destroy(set); +err3: + kfree(set->name); err2: kvfree(set); err1: -- cgit v1.2.1 From d71efb599ad42ef1e564c652d8084252bdc85edf Mon Sep 17 00:00:00 2001 From: Taehee Yoo Date: Wed, 18 Apr 2018 23:35:34 +0900 Subject: netfilter: nf_tables: fix out-of-bounds in nft_chain_commit_update When chain name is changed, nft_chain_commit_update is called. In the nft_chain_commit_update, trans->ctx.chain->name has old chain name and nft_trans_chain_name(trans) has new chain name. If new chain name is longer than old chain name, KASAN warns slab-out-of-bounds. [ 175.015012] BUG: KASAN: slab-out-of-bounds in strcpy+0x9e/0xb0 [ 175.022735] Write of size 1 at addr ffff880114e022da by task iptables-compat/1458 [ 175.031353] CPU: 0 PID: 1458 Comm: iptables-compat Not tainted 4.16.0-rc7+ #146 [ 175.031353] Hardware name: To be filled by O.E.M. To be filled by O.E.M./Aptio CRB, BIOS 5.6.5 07/08/2015 [ 175.031353] Call Trace: [ 175.031353] dump_stack+0x68/0xa0 [ 175.031353] print_address_description+0xd0/0x260 [ 175.031353] ? strcpy+0x9e/0xb0 [ 175.031353] kasan_report+0x234/0x350 [ 175.031353] __asan_report_store1_noabort+0x1c/0x20 [ 175.031353] strcpy+0x9e/0xb0 [ 175.031353] nf_tables_commit+0x1ccc/0x2990 [ 175.031353] nfnetlink_rcv+0x141e/0x16c0 [ 175.031353] ? nfnetlink_net_init+0x150/0x150 [ 175.031353] ? lock_acquire+0x370/0x370 [ 175.031353] ? lock_acquire+0x370/0x370 [ 175.031353] netlink_unicast+0x444/0x640 [ 175.031353] ? netlink_attachskb+0x700/0x700 [ 175.031353] ? _copy_from_iter_full+0x180/0x740 [ 175.031353] ? kasan_check_write+0x14/0x20 [ 175.031353] ? _copy_from_user+0x9b/0xd0 [ 175.031353] netlink_sendmsg+0x845/0xc70 [ ... ] Steps to reproduce: iptables-compat -N 1 iptables-compat -E 1 aaaaaaaaa Signed-off-by: Taehee Yoo Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/netfilter/nf_tables_api.c') diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 102ad873acb4..04d4e3772584 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -5745,7 +5745,7 @@ static void nft_chain_commit_update(struct nft_trans *trans) struct nft_base_chain *basechain; if (nft_trans_chain_name(trans)) - strcpy(trans->ctx.chain->name, nft_trans_chain_name(trans)); + swap(trans->ctx.chain->name, nft_trans_chain_name(trans)); if (!nft_is_base_chain(trans->ctx.chain)) return; -- cgit v1.2.1