diff options
author | Aaron Conole <aconole@bytheb.org> | 2016-09-21 11:35:07 -0400 |
---|---|---|
committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2016-09-25 14:38:48 +0200 |
commit | e3b37f11e6e4e6b6f02cc762f182ce233d2c1c9d (patch) | |
tree | 09f9f1a8b9e8e7e173e1059c5e251c19a9852df6 /net/netfilter/core.c | |
parent | 54f17bbc52f71e2d313721046627c383d6c5c7da (diff) | |
download | op-kernel-dev-e3b37f11e6e4e6b6f02cc762f182ce233d2c1c9d.zip op-kernel-dev-e3b37f11e6e4e6b6f02cc762f182ce233d2c1c9d.tar.gz |
netfilter: replace list_head with single linked list
The netfilter hook list never uses the prev pointer, and so can be trimmed to
be a simple singly-linked list.
In addition to having a more light weight structure for hook traversal,
struct net becomes 5568 bytes (down from 6400) and struct net_device becomes
2176 bytes (down from 2240).
Signed-off-by: Aaron Conole <aconole@bytheb.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/netfilter/core.c')
-rw-r--r-- | net/netfilter/core.c | 141 |
1 files changed, 92 insertions, 49 deletions
diff --git a/net/netfilter/core.c b/net/netfilter/core.c index 67b7428..72fc514 100644 --- a/net/netfilter/core.c +++ b/net/netfilter/core.c @@ -22,6 +22,7 @@ #include <linux/proc_fs.h> #include <linux/mutex.h> #include <linux/slab.h> +#include <linux/rcupdate.h> #include <net/net_namespace.h> #include <net/sock.h> @@ -61,33 +62,50 @@ EXPORT_SYMBOL(nf_hooks_needed); #endif static DEFINE_MUTEX(nf_hook_mutex); +#define nf_entry_dereference(e) \ + rcu_dereference_protected(e, lockdep_is_held(&nf_hook_mutex)) -static struct list_head *nf_find_hook_list(struct net *net, - const struct nf_hook_ops *reg) +static struct nf_hook_entry *nf_hook_entry_head(struct net *net, + const struct nf_hook_ops *reg) { - struct list_head *hook_list = NULL; + struct nf_hook_entry *hook_head = NULL; if (reg->pf != NFPROTO_NETDEV) - hook_list = &net->nf.hooks[reg->pf][reg->hooknum]; + hook_head = nf_entry_dereference(net->nf.hooks[reg->pf] + [reg->hooknum]); else if (reg->hooknum == NF_NETDEV_INGRESS) { #ifdef CONFIG_NETFILTER_INGRESS if (reg->dev && dev_net(reg->dev) == net) - hook_list = ®->dev->nf_hooks_ingress; + hook_head = + nf_entry_dereference( + reg->dev->nf_hooks_ingress); #endif } - return hook_list; + return hook_head; } -struct nf_hook_entry { - const struct nf_hook_ops *orig_ops; - struct nf_hook_ops ops; -}; +/* must hold nf_hook_mutex */ +static void nf_set_hooks_head(struct net *net, const struct nf_hook_ops *reg, + struct nf_hook_entry *entry) +{ + switch (reg->pf) { + case NFPROTO_NETDEV: + /* We already checked in nf_register_net_hook() that this is + * used from ingress. + */ + rcu_assign_pointer(reg->dev->nf_hooks_ingress, entry); + break; + default: + rcu_assign_pointer(net->nf.hooks[reg->pf][reg->hooknum], + entry); + break; + } +} int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg) { - struct list_head *hook_list; + struct nf_hook_entry *hooks_entry; struct nf_hook_entry *entry; - struct nf_hook_ops *elem; if (reg->pf == NFPROTO_NETDEV && (reg->hooknum != NF_NETDEV_INGRESS || @@ -100,19 +118,30 @@ int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg) entry->orig_ops = reg; entry->ops = *reg; + entry->next = NULL; + + mutex_lock(&nf_hook_mutex); + hooks_entry = nf_hook_entry_head(net, reg); - hook_list = nf_find_hook_list(net, reg); - if (!hook_list) { - kfree(entry); - return -ENOENT; + if (hooks_entry && hooks_entry->orig_ops->priority > reg->priority) { + /* This is the case where we need to insert at the head */ + entry->next = hooks_entry; + hooks_entry = NULL; } - mutex_lock(&nf_hook_mutex); - list_for_each_entry(elem, hook_list, list) { - if (reg->priority < elem->priority) - break; + while (hooks_entry && + reg->priority >= hooks_entry->orig_ops->priority && + nf_entry_dereference(hooks_entry->next)) { + hooks_entry = nf_entry_dereference(hooks_entry->next); + } + + if (hooks_entry) { + entry->next = nf_entry_dereference(hooks_entry->next); + rcu_assign_pointer(hooks_entry->next, entry); + } else { + nf_set_hooks_head(net, reg, entry); } - list_add_rcu(&entry->ops.list, elem->list.prev); + mutex_unlock(&nf_hook_mutex); #ifdef CONFIG_NETFILTER_INGRESS if (reg->pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS) @@ -127,24 +156,33 @@ EXPORT_SYMBOL(nf_register_net_hook); void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg) { - struct list_head *hook_list; - struct nf_hook_entry *entry; - struct nf_hook_ops *elem; - - hook_list = nf_find_hook_list(net, reg); - if (!hook_list) - return; + struct nf_hook_entry *hooks_entry; mutex_lock(&nf_hook_mutex); - list_for_each_entry(elem, hook_list, list) { - entry = container_of(elem, struct nf_hook_entry, ops); - if (entry->orig_ops == reg) { - list_del_rcu(&entry->ops.list); - break; + hooks_entry = nf_hook_entry_head(net, reg); + if (hooks_entry->orig_ops == reg) { + nf_set_hooks_head(net, reg, + nf_entry_dereference(hooks_entry->next)); + goto unlock; + } + while (hooks_entry && nf_entry_dereference(hooks_entry->next)) { + struct nf_hook_entry *next = + nf_entry_dereference(hooks_entry->next); + struct nf_hook_entry *nnext; + + if (next->orig_ops != reg) { + hooks_entry = next; + continue; } + nnext = nf_entry_dereference(next->next); + rcu_assign_pointer(hooks_entry->next, nnext); + hooks_entry = next; + break; } + +unlock: mutex_unlock(&nf_hook_mutex); - if (&elem->list == hook_list) { + if (!hooks_entry) { WARN(1, "nf_unregister_net_hook: hook not found!\n"); return; } @@ -156,10 +194,10 @@ void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg) static_key_slow_dec(&nf_hooks_needed[reg->pf][reg->hooknum]); #endif synchronize_net(); - nf_queue_nf_hook_drop(net, &entry->ops); + nf_queue_nf_hook_drop(net, hooks_entry); /* other cpu might still process nfqueue verdict that used reg */ synchronize_net(); - kfree(entry); + kfree(hooks_entry); } EXPORT_SYMBOL(nf_unregister_net_hook); @@ -258,10 +296,9 @@ void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n) } EXPORT_SYMBOL(nf_unregister_hooks); -unsigned int nf_iterate(struct list_head *head, - struct sk_buff *skb, +unsigned int nf_iterate(struct sk_buff *skb, struct nf_hook_state *state, - struct nf_hook_ops **elemp) + struct nf_hook_entry **entryp) { unsigned int verdict; @@ -269,20 +306,23 @@ unsigned int nf_iterate(struct list_head *head, * The caller must not block between calls to this * function because of risk of continuing from deleted element. */ - list_for_each_entry_continue_rcu((*elemp), head, list) { - if (state->thresh > (*elemp)->priority) + while (*entryp) { + if (state->thresh > (*entryp)->ops.priority) { + *entryp = rcu_dereference((*entryp)->next); continue; + } /* Optimization: we don't need to hold module reference here, since function can't sleep. --RR */ repeat: - verdict = (*elemp)->hook((*elemp)->priv, skb, state); + verdict = (*entryp)->ops.hook((*entryp)->ops.priv, skb, state); if (verdict != NF_ACCEPT) { #ifdef CONFIG_NETFILTER_DEBUG if (unlikely((verdict & NF_VERDICT_MASK) > NF_MAX_VERDICT)) { NFDEBUG("Evil return from %p(%u).\n", - (*elemp)->hook, state->hook); + (*entryp)->ops.hook, state->hook); + *entryp = rcu_dereference((*entryp)->next); continue; } #endif @@ -290,6 +330,7 @@ repeat: return verdict; goto repeat; } + *entryp = rcu_dereference((*entryp)->next); } return NF_ACCEPT; } @@ -299,13 +340,13 @@ repeat: * -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) { - struct nf_hook_ops *elem; + struct nf_hook_entry *entry; unsigned int verdict; int ret = 0; - elem = list_entry_rcu(state->hook_list, struct nf_hook_ops, list); + entry = rcu_dereference(state->hook_entries); next_hook: - verdict = nf_iterate(state->hook_list, skb, state, &elem); + verdict = nf_iterate(skb, state, &entry); if (verdict == NF_ACCEPT || verdict == NF_STOP) { ret = 1; } else if ((verdict & NF_VERDICT_MASK) == NF_DROP) { @@ -314,8 +355,10 @@ next_hook: if (ret == 0) ret = -EPERM; } else if ((verdict & NF_VERDICT_MASK) == NF_QUEUE) { - int err = nf_queue(skb, elem, state, - verdict >> NF_VERDICT_QBITS); + int err; + + RCU_INIT_POINTER(state->hook_entries, entry); + err = nf_queue(skb, state, verdict >> NF_VERDICT_QBITS); if (err < 0) { if (err == -ESRCH && (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS)) @@ -442,7 +485,7 @@ static int __net_init netfilter_net_init(struct net *net) for (i = 0; i < ARRAY_SIZE(net->nf.hooks); i++) { for (h = 0; h < NF_MAX_HOOKS; h++) - INIT_LIST_HEAD(&net->nf.hooks[i][h]); + RCU_INIT_POINTER(net->nf.hooks[i][h], NULL); } #ifdef CONFIG_PROC_FS |