From b118509076b39cc5e616c0680312b5caaca535fe Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Fri, 26 Aug 2022 08:49:16 +0200 Subject: netfilter: remove nf_conntrack_helper sysctl and modparam toggles __nf_ct_try_assign_helper() remains in place but it now requires a template to configure the helper. A toggle to disable automatic helper assignment was added by: a9006892643a ("netfilter: nf_ct_helper: allow to disable automatic helper assignment") in 2012 to address the issues described in "Secure use of iptables and connection tracking helpers". Automatic conntrack helper assignment was disabled by: 3bb398d925ec ("netfilter: nf_ct_helper: disable automatic helper assignment") back in 2016. This patch removes the sysctl and modparam toggles, users now have to rely on explicit conntrack helper configuration via ruleset. Update tools/testing/selftests/netfilter/nft_conntrack_helper.sh to check that auto-assignment does not happen anymore. Acked-by: Aaron Conole Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_conntrack_core.c | 7 +-- net/netfilter/nf_conntrack_helper.c | 80 +++++---------------------------- net/netfilter/nf_conntrack_netlink.c | 5 --- net/netfilter/nf_conntrack_standalone.c | 10 ----- net/netfilter/nft_ct.c | 3 -- 5 files changed, 11 insertions(+), 94 deletions(-) (limited to 'net/netfilter') diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 71c2f4f95d36..1357a2729a4b 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -1782,7 +1782,7 @@ init_conntrack(struct net *net, struct nf_conn *tmpl, } spin_unlock_bh(&nf_conntrack_expect_lock); } - if (!exp) + if (!exp && tmpl) __nf_ct_try_assign_helper(ct, tmpl, GFP_ATOMIC); /* Other CPU might have obtained a pointer to this object before it was @@ -2068,10 +2068,6 @@ void nf_conntrack_alter_reply(struct nf_conn *ct, ct->tuplehash[IP_CT_DIR_REPLY].tuple = *newreply; if (ct->master || (help && !hlist_empty(&help->expectations))) return; - - rcu_read_lock(); - __nf_ct_try_assign_helper(ct, NULL, GFP_ATOMIC); - rcu_read_unlock(); } EXPORT_SYMBOL_GPL(nf_conntrack_alter_reply); @@ -2797,7 +2793,6 @@ int nf_conntrack_init_net(struct net *net) nf_conntrack_acct_pernet_init(net); nf_conntrack_tstamp_pernet_init(net); nf_conntrack_ecache_pernet_init(net); - nf_conntrack_helper_pernet_init(net); nf_conntrack_proto_pernet_init(net); return 0; diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c index e96b32221444..ff737a76052e 100644 --- a/net/netfilter/nf_conntrack_helper.c +++ b/net/netfilter/nf_conntrack_helper.c @@ -35,11 +35,6 @@ unsigned int nf_ct_helper_hsize __read_mostly; EXPORT_SYMBOL_GPL(nf_ct_helper_hsize); static unsigned int nf_ct_helper_count __read_mostly; -static bool nf_ct_auto_assign_helper __read_mostly = false; -module_param_named(nf_conntrack_helper, nf_ct_auto_assign_helper, bool, 0644); -MODULE_PARM_DESC(nf_conntrack_helper, - "Enable automatic conntrack helper assignment (default 0)"); - static DEFINE_MUTEX(nf_ct_nat_helpers_mutex); static struct list_head nf_ct_nat_helpers __read_mostly; @@ -51,24 +46,6 @@ static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple) (__force __u16)tuple->src.u.all) % nf_ct_helper_hsize; } -static struct nf_conntrack_helper * -__nf_ct_helper_find(const struct nf_conntrack_tuple *tuple) -{ - struct nf_conntrack_helper *helper; - struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) }; - unsigned int h; - - if (!nf_ct_helper_count) - return NULL; - - h = helper_hash(tuple); - hlist_for_each_entry_rcu(helper, &nf_ct_helper_hash[h], hnode) { - if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask)) - return helper; - } - return NULL; -} - struct nf_conntrack_helper * __nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum) { @@ -209,33 +186,11 @@ nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp) } EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add); -static struct nf_conntrack_helper * -nf_ct_lookup_helper(struct nf_conn *ct, struct net *net) -{ - struct nf_conntrack_net *cnet = nf_ct_pernet(net); - - if (!cnet->sysctl_auto_assign_helper) { - if (cnet->auto_assign_helper_warned) - return NULL; - if (!__nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple)) - return NULL; - pr_info("nf_conntrack: default automatic helper assignment " - "has been turned off for security reasons and CT-based " - "firewall rule not found. Use the iptables CT target " - "to attach helpers instead.\n"); - cnet->auto_assign_helper_warned = true; - return NULL; - } - - return __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple); -} - int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl, gfp_t flags) { struct nf_conntrack_helper *helper = NULL; struct nf_conn_help *help; - struct net *net = nf_ct_net(ct); /* We already got a helper explicitly attached. The function * nf_conntrack_alter_reply - in case NAT is in use - asks for looking @@ -246,23 +201,21 @@ int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl, if (test_bit(IPS_HELPER_BIT, &ct->status)) return 0; - if (tmpl != NULL) { - help = nfct_help(tmpl); - if (help != NULL) { - helper = rcu_dereference(help->helper); - set_bit(IPS_HELPER_BIT, &ct->status); - } + if (WARN_ON_ONCE(!tmpl)) + return 0; + + help = nfct_help(tmpl); + if (help != NULL) { + helper = rcu_dereference(help->helper); + set_bit(IPS_HELPER_BIT, &ct->status); } help = nfct_help(ct); if (helper == NULL) { - helper = nf_ct_lookup_helper(ct, net); - if (helper == NULL) { - if (help) - RCU_INIT_POINTER(help->helper, NULL); - return 0; - } + if (help) + RCU_INIT_POINTER(help->helper, NULL); + return 0; } if (help == NULL) { @@ -545,19 +498,6 @@ void nf_nat_helper_unregister(struct nf_conntrack_nat_helper *nat) } EXPORT_SYMBOL_GPL(nf_nat_helper_unregister); -void nf_ct_set_auto_assign_helper_warned(struct net *net) -{ - nf_ct_pernet(net)->auto_assign_helper_warned = true; -} -EXPORT_SYMBOL_GPL(nf_ct_set_auto_assign_helper_warned); - -void nf_conntrack_helper_pernet_init(struct net *net) -{ - struct nf_conntrack_net *cnet = nf_ct_pernet(net); - - cnet->sysctl_auto_assign_helper = nf_ct_auto_assign_helper; -} - int nf_conntrack_helper_init(void) { nf_ct_helper_hsize = 1; /* gets rounded up to use one page */ diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c index 04169b54f2a2..7562b215b932 100644 --- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -2298,11 +2298,6 @@ ctnetlink_create_conntrack(struct net *net, ct->status |= IPS_HELPER; RCU_INIT_POINTER(help->helper, helper); } - } else { - /* try an implicit helper assignation */ - err = __nf_ct_try_assign_helper(ct, NULL, GFP_ATOMIC); - if (err < 0) - goto err2; } err = ctnetlink_setup_nat(ct, cda); diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c index 05895878610c..4ffe84c5a82c 100644 --- a/net/netfilter/nf_conntrack_standalone.c +++ b/net/netfilter/nf_conntrack_standalone.c @@ -561,7 +561,6 @@ enum nf_ct_sysctl_index { NF_SYSCTL_CT_LOG_INVALID, NF_SYSCTL_CT_EXPECT_MAX, NF_SYSCTL_CT_ACCT, - NF_SYSCTL_CT_HELPER, #ifdef CONFIG_NF_CONNTRACK_EVENTS NF_SYSCTL_CT_EVENTS, #endif @@ -680,14 +679,6 @@ static struct ctl_table nf_ct_sysctl_table[] = { .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_ONE, }, - [NF_SYSCTL_CT_HELPER] = { - .procname = "nf_conntrack_helper", - .maxlen = sizeof(u8), - .mode = 0644, - .proc_handler = proc_dou8vec_minmax, - .extra1 = SYSCTL_ZERO, - .extra2 = SYSCTL_ONE, - }, #ifdef CONFIG_NF_CONNTRACK_EVENTS [NF_SYSCTL_CT_EVENTS] = { .procname = "nf_conntrack_events", @@ -1100,7 +1091,6 @@ static int nf_conntrack_standalone_init_sysctl(struct net *net) table[NF_SYSCTL_CT_CHECKSUM].data = &net->ct.sysctl_checksum; table[NF_SYSCTL_CT_LOG_INVALID].data = &net->ct.sysctl_log_invalid; table[NF_SYSCTL_CT_ACCT].data = &net->ct.sysctl_acct; - table[NF_SYSCTL_CT_HELPER].data = &cnet->sysctl_auto_assign_helper; #ifdef CONFIG_NF_CONNTRACK_EVENTS table[NF_SYSCTL_CT_EVENTS].data = &net->ct.sysctl_events; #endif diff --git a/net/netfilter/nft_ct.c b/net/netfilter/nft_ct.c index b04995c3e17f..a3f01f209a53 100644 --- a/net/netfilter/nft_ct.c +++ b/net/netfilter/nft_ct.c @@ -1089,9 +1089,6 @@ static int nft_ct_helper_obj_init(const struct nft_ctx *ctx, if (err < 0) goto err_put_helper; - /* Avoid the bogus warning, helper will be assigned after CT init */ - nf_ct_set_auto_assign_helper_warned(ctx->net); - return 0; err_put_helper: -- cgit v1.2.3