| /* netfilter.c: look after the filters for various protocols. |
| * Heavily influenced by the old firewall.c by David Bonn and Alan Cox. |
| * |
| * Thanks to Rob `CmdrTaco' Malda for not influencing this code in any |
| * way. |
| * |
| * Rusty Russell (C)2000 -- This code is GPL. |
| * Patrick McHardy (c) 2006-2012 |
| */ |
| #include <linux/kernel.h> |
| #include <linux/netfilter.h> |
| #include <net/protocol.h> |
| #include <linux/init.h> |
| #include <linux/skbuff.h> |
| #include <linux/wait.h> |
| #include <linux/module.h> |
| #include <linux/interrupt.h> |
| #include <linux/if.h> |
| #include <linux/netdevice.h> |
| #include <linux/netfilter_ipv6.h> |
| #include <linux/inetdevice.h> |
| #include <linux/proc_fs.h> |
| #include <linux/mutex.h> |
| #include <linux/mm.h> |
| #include <linux/rcupdate.h> |
| #include <net/net_namespace.h> |
| #include <net/sock.h> |
| |
| #include "nf_internals.h" |
| |
| static DEFINE_MUTEX(afinfo_mutex); |
| |
| const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO] __read_mostly; |
| EXPORT_SYMBOL(nf_afinfo); |
| const struct nf_ipv6_ops __rcu *nf_ipv6_ops __read_mostly; |
| EXPORT_SYMBOL_GPL(nf_ipv6_ops); |
| |
| DEFINE_PER_CPU(bool, nf_skb_duplicated); |
| EXPORT_SYMBOL_GPL(nf_skb_duplicated); |
| |
| int nf_register_afinfo(const struct nf_afinfo *afinfo) |
| { |
| mutex_lock(&afinfo_mutex); |
| RCU_INIT_POINTER(nf_afinfo[afinfo->family], afinfo); |
| mutex_unlock(&afinfo_mutex); |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(nf_register_afinfo); |
| |
| void nf_unregister_afinfo(const struct nf_afinfo *afinfo) |
| { |
| mutex_lock(&afinfo_mutex); |
| RCU_INIT_POINTER(nf_afinfo[afinfo->family], NULL); |
| mutex_unlock(&afinfo_mutex); |
| synchronize_rcu(); |
| } |
| EXPORT_SYMBOL_GPL(nf_unregister_afinfo); |
| |
| #ifdef HAVE_JUMP_LABEL |
| struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS]; |
| EXPORT_SYMBOL(nf_hooks_needed); |
| #endif |
| |
| static DEFINE_MUTEX(nf_hook_mutex); |
| |
| /* max hooks per family/hooknum */ |
| #define MAX_HOOK_COUNT 1024 |
| |
| #define nf_entry_dereference(e) \ |
| rcu_dereference_protected(e, lockdep_is_held(&nf_hook_mutex)) |
| |
| static struct nf_hook_entries *allocate_hook_entries_size(u16 num) |
| { |
| struct nf_hook_entries *e; |
| size_t alloc = sizeof(*e) + |
| sizeof(struct nf_hook_entry) * num + |
| sizeof(struct nf_hook_ops *) * num; |
| |
| if (num == 0) |
| return NULL; |
| |
| e = kvzalloc(alloc, GFP_KERNEL); |
| if (e) |
| e->num_hook_entries = num; |
| return e; |
| } |
| |
| static unsigned int accept_all(void *priv, |
| struct sk_buff *skb, |
| const struct nf_hook_state *state) |
| { |
| return NF_ACCEPT; /* ACCEPT makes nf_hook_slow call next hook */ |
| } |
| |
| static const struct nf_hook_ops dummy_ops = { |
| .hook = accept_all, |
| .priority = INT_MIN, |
| }; |
| |
| static struct nf_hook_entries * |
| nf_hook_entries_grow(const struct nf_hook_entries *old, |
| const struct nf_hook_ops *reg) |
| { |
| unsigned int i, alloc_entries, nhooks, old_entries; |
| struct nf_hook_ops **orig_ops = NULL; |
| struct nf_hook_ops **new_ops; |
| struct nf_hook_entries *new; |
| bool inserted = false; |
| |
| alloc_entries = 1; |
| old_entries = old ? old->num_hook_entries : 0; |
| |
| if (old) { |
| orig_ops = nf_hook_entries_get_hook_ops(old); |
| |
| for (i = 0; i < old_entries; i++) { |
| if (orig_ops[i] != &dummy_ops) |
| alloc_entries++; |
| } |
| } |
| |
| if (alloc_entries > MAX_HOOK_COUNT) |
| return ERR_PTR(-E2BIG); |
| |
| new = allocate_hook_entries_size(alloc_entries); |
| if (!new) |
| return ERR_PTR(-ENOMEM); |
| |
| new_ops = nf_hook_entries_get_hook_ops(new); |
| |
| i = 0; |
| nhooks = 0; |
| while (i < old_entries) { |
| if (orig_ops[i] == &dummy_ops) { |
| ++i; |
| continue; |
| } |
| if (inserted || reg->priority > orig_ops[i]->priority) { |
| new_ops[nhooks] = (void *)orig_ops[i]; |
| new->hooks[nhooks] = old->hooks[i]; |
| i++; |
| } else { |
| new_ops[nhooks] = (void *)reg; |
| new->hooks[nhooks].hook = reg->hook; |
| new->hooks[nhooks].priv = reg->priv; |
| inserted = true; |
| } |
| nhooks++; |
| } |
| |
| if (!inserted) { |
| new_ops[nhooks] = (void *)reg; |
| new->hooks[nhooks].hook = reg->hook; |
| new->hooks[nhooks].priv = reg->priv; |
| } |
| |
| return new; |
| } |
| |
| static void hooks_validate(const struct nf_hook_entries *hooks) |
| { |
| #ifdef CONFIG_DEBUG_KERNEL |
| struct nf_hook_ops **orig_ops; |
| int prio = INT_MIN; |
| size_t i = 0; |
| |
| orig_ops = nf_hook_entries_get_hook_ops(hooks); |
| |
| for (i = 0; i < hooks->num_hook_entries; i++) { |
| if (orig_ops[i] == &dummy_ops) |
| continue; |
| |
| WARN_ON(orig_ops[i]->priority < prio); |
| |
| if (orig_ops[i]->priority > prio) |
| prio = orig_ops[i]->priority; |
| } |
| #endif |
| } |
| |
| /* |
| * __nf_hook_entries_try_shrink - try to shrink hook array |
| * |
| * @pp -- location of hook blob |
| * |
| * Hook unregistration must always succeed, so to-be-removed hooks |
| * are replaced by a dummy one that will just move to next hook. |
| * |
| * This counts the current dummy hooks, attempts to allocate new blob, |
| * copies the live hooks, then replaces and discards old one. |
| * |
| * return values: |
| * |
| * Returns address to free, or NULL. |
| */ |
| static void *__nf_hook_entries_try_shrink(struct nf_hook_entries __rcu **pp) |
| { |
| struct nf_hook_entries *old, *new = NULL; |
| unsigned int i, j, skip = 0, hook_entries; |
| struct nf_hook_ops **orig_ops; |
| struct nf_hook_ops **new_ops; |
| |
| old = nf_entry_dereference(*pp); |
| if (WARN_ON_ONCE(!old)) |
| return NULL; |
| |
| orig_ops = nf_hook_entries_get_hook_ops(old); |
| for (i = 0; i < old->num_hook_entries; i++) { |
| if (orig_ops[i] == &dummy_ops) |
| skip++; |
| } |
| |
| /* if skip == hook_entries all hooks have been removed */ |
| hook_entries = old->num_hook_entries; |
| if (skip == hook_entries) |
| goto out_assign; |
| |
| if (skip == 0) |
| return NULL; |
| |
| hook_entries -= skip; |
| new = allocate_hook_entries_size(hook_entries); |
| if (!new) |
| return NULL; |
| |
| new_ops = nf_hook_entries_get_hook_ops(new); |
| for (i = 0, j = 0; i < old->num_hook_entries; i++) { |
| if (orig_ops[i] == &dummy_ops) |
| continue; |
| new->hooks[j] = old->hooks[i]; |
| new_ops[j] = (void *)orig_ops[i]; |
| j++; |
| } |
| hooks_validate(new); |
| out_assign: |
| rcu_assign_pointer(*pp, new); |
| return old; |
| } |
| |
| static struct nf_hook_entries __rcu **nf_hook_entry_head(struct net *net, const struct nf_hook_ops *reg) |
| { |
| if (reg->pf != NFPROTO_NETDEV) |
| return net->nf.hooks[reg->pf]+reg->hooknum; |
| |
| #ifdef CONFIG_NETFILTER_INGRESS |
| if (reg->hooknum == NF_NETDEV_INGRESS) { |
| if (reg->dev && dev_net(reg->dev) == net) |
| return ®->dev->nf_hooks_ingress; |
| } |
| #endif |
| WARN_ON_ONCE(1); |
| return NULL; |
| } |
| |
| int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg) |
| { |
| struct nf_hook_entries *p, *new_hooks; |
| struct nf_hook_entries __rcu **pp; |
| |
| if (reg->pf == NFPROTO_NETDEV) { |
| #ifndef CONFIG_NETFILTER_INGRESS |
| if (reg->hooknum == NF_NETDEV_INGRESS) |
| return -EOPNOTSUPP; |
| #endif |
| if (reg->hooknum != NF_NETDEV_INGRESS || |
| !reg->dev || dev_net(reg->dev) != net) |
| return -EINVAL; |
| } |
| |
| pp = nf_hook_entry_head(net, reg); |
| if (!pp) |
| return -EINVAL; |
| |
| mutex_lock(&nf_hook_mutex); |
| |
| p = nf_entry_dereference(*pp); |
| new_hooks = nf_hook_entries_grow(p, reg); |
| |
| if (!IS_ERR(new_hooks)) |
| rcu_assign_pointer(*pp, new_hooks); |
| |
| mutex_unlock(&nf_hook_mutex); |
| if (IS_ERR(new_hooks)) |
| return PTR_ERR(new_hooks); |
| |
| hooks_validate(new_hooks); |
| #ifdef CONFIG_NETFILTER_INGRESS |
| if (reg->pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS) |
| net_inc_ingress_queue(); |
| #endif |
| #ifdef HAVE_JUMP_LABEL |
| static_key_slow_inc(&nf_hooks_needed[reg->pf][reg->hooknum]); |
| #endif |
| synchronize_net(); |
| BUG_ON(p == new_hooks); |
| kvfree(p); |
| return 0; |
| } |
| EXPORT_SYMBOL(nf_register_net_hook); |
| |
| /* |
| * __nf_unregister_net_hook - remove a hook from blob |
| * |
| * @oldp: current address of hook blob |
| * @unreg: hook to unregister |
| * |
| * This cannot fail, hook unregistration must always succeed. |
| * Therefore replace the to-be-removed hook with a dummy hook. |
| */ |
| static void __nf_unregister_net_hook(struct nf_hook_entries *old, |
| const struct nf_hook_ops *unreg) |
| { |
| struct nf_hook_ops **orig_ops; |
| bool found = false; |
| unsigned int i; |
| |
| orig_ops = nf_hook_entries_get_hook_ops(old); |
| for (i = 0; i < old->num_hook_entries; i++) { |
| if (orig_ops[i] != unreg) |
| continue; |
| WRITE_ONCE(old->hooks[i].hook, accept_all); |
| WRITE_ONCE(orig_ops[i], &dummy_ops); |
| found = true; |
| break; |
| } |
| |
| if (found) { |
| #ifdef CONFIG_NETFILTER_INGRESS |
| if (unreg->pf == NFPROTO_NETDEV && unreg->hooknum == NF_NETDEV_INGRESS) |
| net_dec_ingress_queue(); |
| #endif |
| #ifdef HAVE_JUMP_LABEL |
| static_key_slow_dec(&nf_hooks_needed[unreg->pf][unreg->hooknum]); |
| #endif |
| } else { |
| WARN_ONCE(1, "hook not found, pf %d num %d", unreg->pf, unreg->hooknum); |
| } |
| } |
| |
| void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg) |
| { |
| struct nf_hook_entries __rcu **pp; |
| struct nf_hook_entries *p; |
| unsigned int nfq; |
| |
| pp = nf_hook_entry_head(net, reg); |
| if (!pp) |
| return; |
| |
| mutex_lock(&nf_hook_mutex); |
| |
| p = nf_entry_dereference(*pp); |
| if (WARN_ON_ONCE(!p)) { |
| mutex_unlock(&nf_hook_mutex); |
| return; |
| } |
| |
| __nf_unregister_net_hook(p, reg); |
| |
| p = __nf_hook_entries_try_shrink(pp); |
| mutex_unlock(&nf_hook_mutex); |
| if (!p) |
| return; |
| |
| synchronize_net(); |
| |
| /* other cpu might still process nfqueue verdict that used reg */ |
| nfq = nf_queue_nf_hook_drop(net); |
| if (nfq) |
| synchronize_net(); |
| kvfree(p); |
| } |
| EXPORT_SYMBOL(nf_unregister_net_hook); |
| |
| int nf_register_net_hooks(struct net *net, const struct nf_hook_ops *reg, |
| unsigned int n) |
| { |
| unsigned int i; |
| int err = 0; |
| |
| for (i = 0; i < n; i++) { |
| err = nf_register_net_hook(net, ®[i]); |
| if (err) |
| goto err; |
| } |
| return err; |
| |
| err: |
| if (i > 0) |
| nf_unregister_net_hooks(net, reg, i); |
| return err; |
| } |
| EXPORT_SYMBOL(nf_register_net_hooks); |
| |
| void nf_unregister_net_hooks(struct net *net, const struct nf_hook_ops *reg, |
| unsigned int hookcount) |
| { |
| struct nf_hook_entries *to_free[16], *p; |
| struct nf_hook_entries __rcu **pp; |
| unsigned int i, j, n; |
| |
| mutex_lock(&nf_hook_mutex); |
| for (i = 0; i < hookcount; i++) { |
| pp = nf_hook_entry_head(net, ®[i]); |
| if (!pp) |
| continue; |
| |
| p = nf_entry_dereference(*pp); |
| if (WARN_ON_ONCE(!p)) |
| continue; |
| __nf_unregister_net_hook(p, ®[i]); |
| } |
| mutex_unlock(&nf_hook_mutex); |
| |
| do { |
| n = min_t(unsigned int, hookcount, ARRAY_SIZE(to_free)); |
| |
| mutex_lock(&nf_hook_mutex); |
| |
| for (i = 0, j = 0; i < hookcount && j < n; i++) { |
| pp = nf_hook_entry_head(net, ®[i]); |
| if (!pp) |
| continue; |
| |
| p = nf_entry_dereference(*pp); |
| if (!p) |
| continue; |
| |
| to_free[j] = __nf_hook_entries_try_shrink(pp); |
| if (to_free[j]) |
| ++j; |
| } |
| |
| mutex_unlock(&nf_hook_mutex); |
| |
| if (j) { |
| unsigned int nfq; |
| |
| synchronize_net(); |
| |
| /* need 2nd synchronize_net() if nfqueue is used, skb |
| * can get reinjected right before nf_queue_hook_drop() |
| */ |
| nfq = nf_queue_nf_hook_drop(net); |
| if (nfq) |
| synchronize_net(); |
| |
| for (i = 0; i < j; i++) |
| kvfree(to_free[i]); |
| } |
| |
| reg += n; |
| hookcount -= n; |
| } while (hookcount > 0); |
| } |
| EXPORT_SYMBOL(nf_unregister_net_hooks); |
| |
| /* Returns 1 if okfn() needs to be executed by the caller, |
| * -EPERM for NF_DROP, 0 otherwise. Caller must hold rcu_read_lock. */ |
| int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state, |
| const struct nf_hook_entries *e, unsigned int s) |
| { |
| unsigned int verdict; |
| int ret; |
| |
| for (; s < e->num_hook_entries; s++) { |
| verdict = nf_hook_entry_hookfn(&e->hooks[s], skb, state); |
| switch (verdict & NF_VERDICT_MASK) { |
| case NF_ACCEPT: |
| break; |
| case NF_DROP: |
| kfree_skb(skb); |
| ret = NF_DROP_GETERR(verdict); |
| if (ret == 0) |
| ret = -EPERM; |
| return ret; |
| case NF_QUEUE: |
| ret = nf_queue(skb, state, e, s, verdict); |
| if (ret == 1) |
| continue; |
| return ret; |
| default: |
| /* Implicit handling for NF_STOLEN, as well as any other |
| * non conventional verdicts. |
| */ |
| return 0; |
| } |
| } |
| |
| return 1; |
| } |
| EXPORT_SYMBOL(nf_hook_slow); |
| |
| |
| int skb_make_writable(struct sk_buff *skb, unsigned int writable_len) |
| { |
| if (writable_len > skb->len) |
| return 0; |
| |
| /* Not exclusive use of packet? Must copy. */ |
| if (!skb_cloned(skb)) { |
| if (writable_len <= skb_headlen(skb)) |
| return 1; |
| } else if (skb_clone_writable(skb, writable_len)) |
| return 1; |
| |
| if (writable_len <= skb_headlen(skb)) |
| writable_len = 0; |
| else |
| writable_len -= skb_headlen(skb); |
| |
| return !!__pskb_pull_tail(skb, writable_len); |
| } |
| EXPORT_SYMBOL(skb_make_writable); |
| |
| /* This needs to be compiled in any case to avoid dependencies between the |
| * nfnetlink_queue code and nf_conntrack. |
| */ |
| struct nfnl_ct_hook __rcu *nfnl_ct_hook __read_mostly; |
| EXPORT_SYMBOL_GPL(nfnl_ct_hook); |
| |
| #if IS_ENABLED(CONFIG_NF_CONNTRACK) |
| /* This does not belong here, but locally generated errors need it if connection |
| tracking in use: without this, connection may not be in hash table, and hence |
| manufactured ICMP or RST packets will not be associated with it. */ |
| void (*ip_ct_attach)(struct sk_buff *, const struct sk_buff *) |
| __rcu __read_mostly; |
| EXPORT_SYMBOL(ip_ct_attach); |
| |
| void nf_ct_attach(struct sk_buff *new, const struct sk_buff *skb) |
| { |
| void (*attach)(struct sk_buff *, const struct sk_buff *); |
| |
| if (skb->_nfct) { |
| rcu_read_lock(); |
| attach = rcu_dereference(ip_ct_attach); |
| if (attach) |
| attach(new, skb); |
| rcu_read_unlock(); |
| } |
| } |
| EXPORT_SYMBOL(nf_ct_attach); |
| |
| void (*nf_ct_destroy)(struct nf_conntrack *) __rcu __read_mostly; |
| EXPORT_SYMBOL(nf_ct_destroy); |
| |
| void nf_conntrack_destroy(struct nf_conntrack *nfct) |
| { |
| void (*destroy)(struct nf_conntrack *); |
| |
| rcu_read_lock(); |
| destroy = rcu_dereference(nf_ct_destroy); |
| BUG_ON(destroy == NULL); |
| destroy(nfct); |
| rcu_read_unlock(); |
| } |
| EXPORT_SYMBOL(nf_conntrack_destroy); |
| |
| /* Built-in default zone used e.g. by modules. */ |
| const struct nf_conntrack_zone nf_ct_zone_dflt = { |
| .id = NF_CT_DEFAULT_ZONE_ID, |
| .dir = NF_CT_DEFAULT_ZONE_DIR, |
| }; |
| EXPORT_SYMBOL_GPL(nf_ct_zone_dflt); |
| #endif /* CONFIG_NF_CONNTRACK */ |
| |
| #ifdef CONFIG_NF_NAT_NEEDED |
| void (*nf_nat_decode_session_hook)(struct sk_buff *, struct flowi *); |
| EXPORT_SYMBOL(nf_nat_decode_session_hook); |
| #endif |
| |
| static int __net_init netfilter_net_init(struct net *net) |
| { |
| int i, h; |
| |
| for (i = 0; i < ARRAY_SIZE(net->nf.hooks); i++) { |
| for (h = 0; h < NF_MAX_HOOKS; h++) |
| RCU_INIT_POINTER(net->nf.hooks[i][h], NULL); |
| } |
| |
| #ifdef CONFIG_PROC_FS |
| net->nf.proc_netfilter = proc_net_mkdir(net, "netfilter", |
| net->proc_net); |
| if (!net->nf.proc_netfilter) { |
| if (!net_eq(net, &init_net)) |
| pr_err("cannot create netfilter proc entry"); |
| |
| return -ENOMEM; |
| } |
| #endif |
| |
| return 0; |
| } |
| |
| static void __net_exit netfilter_net_exit(struct net *net) |
| { |
| remove_proc_entry("netfilter", net->proc_net); |
| } |
| |
| static struct pernet_operations netfilter_net_ops = { |
| .init = netfilter_net_init, |
| .exit = netfilter_net_exit, |
| }; |
| |
| int __init netfilter_init(void) |
| { |
| int ret; |
| |
| ret = register_pernet_subsys(&netfilter_net_ops); |
| if (ret < 0) |
| goto err; |
| |
| ret = netfilter_log_init(); |
| if (ret < 0) |
| goto err_pernet; |
| |
| return 0; |
| err_pernet: |
| unregister_pernet_subsys(&netfilter_net_ops); |
| err: |
| return ret; |
| } |