From: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> This patch adds the basic infrastructure to support user-space expectation helpers via ctnetlink and the netfilter queuing infrastructure NFQUEUE. Basically, this patch: * adds NF_CT_EXPECT_USERSPACE flag to identify user-space created expectations. I have also added a sanity check in __nf_ct_expect_check() to avoid that kernel-space helpers may create an expectation if the master conntrack has no helper assigned. * adds some branches to check if the master conntrack helper exists, otherwise we skip the code that refers to kernel-space helper such as the local expectation list and the expectation policy. * allows to set the timeout for user-space expectations with no helper assigned. * a list of expectations created from user-space that depends on ctnetlink (if this module is removed, they are deleted). * includes USERSPACE in the /proc output for expectations that have been created by a user-space helper. This patch also modifies ctnetlink to skip including the helper name in the Netlink messages if no kernel-space helper is set (since no user-space expectation has not kernel-space kernel assigned). You can access an example user-space FTP conntrack helper at: http://people.netfilter.org/pablo/userspace-conntrack-helpers/nf-ftp-helper-userspace-POC.tar.bz Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx> --- include/linux/netfilter/nf_conntrack_common.h | 1 + include/net/netfilter/nf_conntrack_expect.h | 1 + net/netfilter/nf_conntrack_expect.c | 62 +++++++++++++++++++------ net/netfilter/nf_conntrack_netlink.c | 46 ++++++++++++------ 4 files changed, 79 insertions(+), 31 deletions(-) diff --git a/include/linux/netfilter/nf_conntrack_common.h b/include/linux/netfilter/nf_conntrack_common.h index fdc50ca..23a1a08 100644 --- a/include/linux/netfilter/nf_conntrack_common.h +++ b/include/linux/netfilter/nf_conntrack_common.h @@ -103,6 +103,7 @@ enum ip_conntrack_expect_events { /* expectation flags */ #define NF_CT_EXPECT_PERMANENT 0x1 #define NF_CT_EXPECT_INACTIVE 0x2 +#define NF_CT_EXPECT_USERSPACE 0x4 #ifdef __KERNEL__ struct ip_conntrack_stat { diff --git a/include/net/netfilter/nf_conntrack_expect.h b/include/net/netfilter/nf_conntrack_expect.h index 96bb42a..416b838 100644 --- a/include/net/netfilter/nf_conntrack_expect.h +++ b/include/net/netfilter/nf_conntrack_expect.h @@ -85,6 +85,7 @@ nf_ct_find_expectation(struct net *net, u16 zone, void nf_ct_unlink_expect(struct nf_conntrack_expect *exp); void nf_ct_remove_expectations(struct nf_conn *ct); void nf_ct_unexpect_related(struct nf_conntrack_expect *exp); +void nf_ct_remove_userspace_expectations(void); /* Allocate space for an expectation: this is mandatory before calling nf_ct_expect_related. You will have to call put afterwards. */ diff --git a/net/netfilter/nf_conntrack_expect.c b/net/netfilter/nf_conntrack_expect.c index acb29cc..b30a1f2 100644 --- a/net/netfilter/nf_conntrack_expect.c +++ b/net/netfilter/nf_conntrack_expect.c @@ -38,20 +38,23 @@ static int nf_ct_expect_hash_rnd_initted __read_mostly; static struct kmem_cache *nf_ct_expect_cachep __read_mostly; +static HLIST_HEAD(nf_ct_userspace_expect_list); + /* nf_conntrack_expect helper functions */ void nf_ct_unlink_expect(struct nf_conntrack_expect *exp) { struct nf_conn_help *master_help = nfct_help(exp->master); struct net *net = nf_ct_exp_net(exp); - NF_CT_ASSERT(master_help); NF_CT_ASSERT(!timer_pending(&exp->timeout)); hlist_del_rcu(&exp->hnode); net->ct.expect_count--; hlist_del(&exp->lnode); - master_help->expecting[exp->class]--; + if (!(exp->flags & NF_CT_EXPECT_USERSPACE)) + master_help->expecting[exp->class]--; + nf_ct_expect_put(exp); NF_CT_STAT_INC(net, expect_delete); @@ -320,16 +323,21 @@ static void nf_ct_expect_insert(struct nf_conntrack_expect *exp) atomic_inc(&exp->use); - hlist_add_head(&exp->lnode, &master_help->expectations); - master_help->expecting[exp->class]++; + if (master_help) { + hlist_add_head(&exp->lnode, &master_help->expectations); + master_help->expecting[exp->class]++; + } else if (exp->flags & NF_CT_EXPECT_USERSPACE) + hlist_add_head(&exp->lnode, &nf_ct_userspace_expect_list); hlist_add_head_rcu(&exp->hnode, &net->ct.expect_hash[h]); net->ct.expect_count++; setup_timer(&exp->timeout, nf_ct_expectation_timed_out, (unsigned long)exp); - p = &master_help->helper->expect_policy[exp->class]; - exp->timeout.expires = jiffies + p->timeout * HZ; + if (master_help) { + p = &master_help->helper->expect_policy[exp->class]; + exp->timeout.expires = jiffies + p->timeout * HZ; + } add_timer(&exp->timeout); atomic_inc(&exp->use); @@ -380,7 +388,9 @@ static inline int __nf_ct_expect_check(struct nf_conntrack_expect *expect) unsigned int h; int ret = 1; - if (!master_help->helper) { + /* Don't allow expectations created from kernel-space with no helper */ + if (!(expect->flags & NF_CT_EXPECT_USERSPACE) && + (!master_help || (master_help && !master_help->helper))) { ret = -ESHUTDOWN; goto out; } @@ -398,13 +408,16 @@ static inline int __nf_ct_expect_check(struct nf_conntrack_expect *expect) } } /* Will be over limit? */ - p = &master_help->helper->expect_policy[expect->class]; - if (p->max_expected && - master_help->expecting[expect->class] >= p->max_expected) { - evict_oldest_expect(master, expect); - if (master_help->expecting[expect->class] >= p->max_expected) { - ret = -EMFILE; - goto out; + if (master_help) { + p = &master_help->helper->expect_policy[expect->class]; + if (p->max_expected && + master_help->expecting[expect->class] >= p->max_expected) { + evict_oldest_expect(master, expect); + if (master_help->expecting[expect->class] + >= p->max_expected) { + ret = -EMFILE; + goto out; + } } } @@ -439,6 +452,21 @@ out: } EXPORT_SYMBOL_GPL(nf_ct_expect_related_report); +void nf_ct_remove_userspace_expectations(void) +{ + struct nf_conntrack_expect *exp; + struct hlist_node *n, *next; + + hlist_for_each_entry_safe(exp, n, next, + &nf_ct_userspace_expect_list, lnode) { + if (del_timer(&exp->timeout)) { + nf_ct_unlink_expect(exp); + nf_ct_expect_put(exp); + } + } +} +EXPORT_SYMBOL_GPL(nf_ct_remove_userspace_expectations); + #ifdef CONFIG_PROC_FS struct ct_expect_iter_state { struct seq_net_private p; @@ -529,8 +557,12 @@ static int exp_seq_show(struct seq_file *s, void *v) seq_printf(s, "PERMANENT"); delim = ","; } - if (expect->flags & NF_CT_EXPECT_INACTIVE) + if (expect->flags & NF_CT_EXPECT_INACTIVE) { seq_printf(s, "%sINACTIVE", delim); + delim = ","; + } + if (expect->flags & NF_CT_EXPECT_USERSPACE) + seq_printf(s, "%sUSERSPACE", delim); helper = rcu_dereference(nfct_help(expect->master)->helper); if (helper) { diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c index 0804e0e..b4077be 100644 --- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -1560,8 +1560,8 @@ ctnetlink_exp_dump_expect(struct sk_buff *skb, const struct nf_conntrack_expect *exp) { struct nf_conn *master = exp->master; - struct nf_conntrack_helper *helper; long timeout = (exp->timeout.expires - jiffies) / HZ; + struct nf_conn_help *help; if (timeout < 0) timeout = 0; @@ -1578,9 +1578,14 @@ ctnetlink_exp_dump_expect(struct sk_buff *skb, NLA_PUT_BE32(skb, CTA_EXPECT_TIMEOUT, htonl(timeout)); NLA_PUT_BE32(skb, CTA_EXPECT_ID, htonl((unsigned long)exp)); NLA_PUT_BE32(skb, CTA_EXPECT_FLAGS, htonl(exp->flags)); - helper = rcu_dereference(nfct_help(master)->helper); - if (helper) - NLA_PUT_STRING(skb, CTA_EXPECT_HELP_NAME, helper->name); + help = nfct_help(master); + if (help) { + struct nf_conntrack_helper *helper; + + helper = rcu_dereference(help->helper); + if (helper) + NLA_PUT_STRING(skb, CTA_EXPECT_HELP_NAME, helper->name); + } return 0; @@ -1921,24 +1926,32 @@ ctnetlink_create_expect(struct net *net, u16 zone, if (!h) return -ENOENT; ct = nf_ct_tuplehash_to_ctrack(h); - help = nfct_help(ct); - - if (!help || !help->helper) { - /* such conntrack hasn't got any helper, abort */ - err = -EOPNOTSUPP; - goto out; - } - exp = nf_ct_expect_alloc(ct); if (!exp) { err = -ENOMEM; goto out; } + help = nfct_help(ct); + if (!help) { + if (!cda[CTA_EXPECT_TIMEOUT]) { + err = -EINVAL; + goto out; + } + exp->timeout.expires = + jiffies + ntohl(nla_get_be32(cda[CTA_EXPECT_TIMEOUT])) * HZ; - if (cda[CTA_EXPECT_FLAGS]) - exp->flags = ntohl(nla_get_be32(cda[CTA_EXPECT_FLAGS])); - else - exp->flags = 0; + exp->flags = NF_CT_EXPECT_USERSPACE; + if (cda[CTA_EXPECT_FLAGS]) { + exp->flags |= + ntohl(nla_get_be32(cda[CTA_EXPECT_FLAGS])); + } + } else { + if (cda[CTA_EXPECT_FLAGS]) { + exp->flags = ntohl(nla_get_be32(cda[CTA_EXPECT_FLAGS])); + exp->flags &= ~NF_CT_EXPECT_USERSPACE; + } else + exp->flags = 0; + } exp->class = 0; exp->expectfn = NULL; @@ -2109,6 +2122,7 @@ static void __exit ctnetlink_exit(void) { pr_info("ctnetlink: unregistering from nfnetlink.\n"); + nf_ct_remove_userspace_expectations(); #ifdef CONFIG_NF_CONNTRACK_EVENTS nf_ct_expect_unregister_notifier(&ctnl_notifier_exp); nf_conntrack_unregister_notifier(&ctnl_notifier); -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
