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![Pablo Neira Ayuso](/assets/img/avatar_default.png)
Overflow use refcount checks are not complete.
Add helper function to deal with object reference counter tracking.
Report -EMFILE in case UINT_MAX is reached.
nft_use_dec() splats in case that reference counter underflows,
which should not ever happen.
Add nft_use_inc_restore() and nft_use_dec_restore() which are used
to restore reference counter from error and abort paths.
Use u32 in nft_flowtable and nft_object since helper functions cannot
work on bitfields.
Remove the few early incomplete checks now that the helper functions
are in place and used to check for refcount overflow.
Fixes: 96518518cc
("netfilter: add nftables")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
527 lines
13 KiB
C
527 lines
13 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/netlink.h>
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#include <linux/netfilter.h>
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#include <linux/workqueue.h>
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#include <linux/spinlock.h>
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#include <linux/netfilter/nf_conntrack_common.h>
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#include <linux/netfilter/nf_tables.h>
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#include <net/ip.h> /* for ipv4 options. */
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#include <net/netfilter/nf_tables.h>
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#include <net/netfilter/nf_tables_core.h>
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#include <net/netfilter/nf_conntrack_core.h>
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#include <net/netfilter/nf_conntrack_extend.h>
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#include <net/netfilter/nf_flow_table.h>
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struct nft_flow_offload {
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struct nft_flowtable *flowtable;
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};
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static enum flow_offload_xmit_type nft_xmit_type(struct dst_entry *dst)
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{
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if (dst_xfrm(dst))
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return FLOW_OFFLOAD_XMIT_XFRM;
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return FLOW_OFFLOAD_XMIT_NEIGH;
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}
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static void nft_default_forward_path(struct nf_flow_route *route,
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struct dst_entry *dst_cache,
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enum ip_conntrack_dir dir)
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{
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route->tuple[!dir].in.ifindex = dst_cache->dev->ifindex;
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route->tuple[dir].dst = dst_cache;
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route->tuple[dir].xmit_type = nft_xmit_type(dst_cache);
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}
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static bool nft_is_valid_ether_device(const struct net_device *dev)
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{
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if (!dev || (dev->flags & IFF_LOOPBACK) || dev->type != ARPHRD_ETHER ||
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dev->addr_len != ETH_ALEN || !is_valid_ether_addr(dev->dev_addr))
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return false;
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return true;
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}
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static int nft_dev_fill_forward_path(const struct nf_flow_route *route,
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const struct dst_entry *dst_cache,
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const struct nf_conn *ct,
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enum ip_conntrack_dir dir, u8 *ha,
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struct net_device_path_stack *stack)
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{
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const void *daddr = &ct->tuplehash[!dir].tuple.src.u3;
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struct net_device *dev = dst_cache->dev;
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struct neighbour *n;
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u8 nud_state;
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if (!nft_is_valid_ether_device(dev))
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goto out;
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n = dst_neigh_lookup(dst_cache, daddr);
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if (!n)
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return -1;
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read_lock_bh(&n->lock);
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nud_state = n->nud_state;
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ether_addr_copy(ha, n->ha);
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read_unlock_bh(&n->lock);
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neigh_release(n);
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if (!(nud_state & NUD_VALID))
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return -1;
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out:
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return dev_fill_forward_path(dev, ha, stack);
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}
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struct nft_forward_info {
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const struct net_device *indev;
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const struct net_device *outdev;
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const struct net_device *hw_outdev;
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struct id {
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__u16 id;
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__be16 proto;
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} encap[NF_FLOW_TABLE_ENCAP_MAX];
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u8 num_encaps;
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u8 ingress_vlans;
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u8 h_source[ETH_ALEN];
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u8 h_dest[ETH_ALEN];
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enum flow_offload_xmit_type xmit_type;
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};
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static void nft_dev_path_info(const struct net_device_path_stack *stack,
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struct nft_forward_info *info,
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unsigned char *ha, struct nf_flowtable *flowtable)
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{
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const struct net_device_path *path;
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int i;
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memcpy(info->h_dest, ha, ETH_ALEN);
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for (i = 0; i < stack->num_paths; i++) {
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path = &stack->path[i];
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switch (path->type) {
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case DEV_PATH_ETHERNET:
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case DEV_PATH_DSA:
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case DEV_PATH_VLAN:
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case DEV_PATH_PPPOE:
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info->indev = path->dev;
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if (is_zero_ether_addr(info->h_source))
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memcpy(info->h_source, path->dev->dev_addr, ETH_ALEN);
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if (path->type == DEV_PATH_ETHERNET)
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break;
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if (path->type == DEV_PATH_DSA) {
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i = stack->num_paths;
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break;
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}
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/* DEV_PATH_VLAN and DEV_PATH_PPPOE */
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if (info->num_encaps >= NF_FLOW_TABLE_ENCAP_MAX) {
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info->indev = NULL;
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break;
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}
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if (!info->outdev)
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info->outdev = path->dev;
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info->encap[info->num_encaps].id = path->encap.id;
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info->encap[info->num_encaps].proto = path->encap.proto;
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info->num_encaps++;
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if (path->type == DEV_PATH_PPPOE)
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memcpy(info->h_dest, path->encap.h_dest, ETH_ALEN);
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break;
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case DEV_PATH_BRIDGE:
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if (is_zero_ether_addr(info->h_source))
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memcpy(info->h_source, path->dev->dev_addr, ETH_ALEN);
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switch (path->bridge.vlan_mode) {
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case DEV_PATH_BR_VLAN_UNTAG_HW:
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info->ingress_vlans |= BIT(info->num_encaps - 1);
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break;
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case DEV_PATH_BR_VLAN_TAG:
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info->encap[info->num_encaps].id = path->bridge.vlan_id;
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info->encap[info->num_encaps].proto = path->bridge.vlan_proto;
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info->num_encaps++;
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break;
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case DEV_PATH_BR_VLAN_UNTAG:
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info->num_encaps--;
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break;
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case DEV_PATH_BR_VLAN_KEEP:
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break;
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}
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info->xmit_type = FLOW_OFFLOAD_XMIT_DIRECT;
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break;
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default:
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info->indev = NULL;
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break;
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}
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}
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if (!info->outdev)
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info->outdev = info->indev;
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info->hw_outdev = info->indev;
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if (nf_flowtable_hw_offload(flowtable) &&
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nft_is_valid_ether_device(info->indev))
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info->xmit_type = FLOW_OFFLOAD_XMIT_DIRECT;
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}
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static bool nft_flowtable_find_dev(const struct net_device *dev,
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struct nft_flowtable *ft)
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{
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struct nft_hook *hook;
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bool found = false;
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list_for_each_entry_rcu(hook, &ft->hook_list, list) {
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if (hook->ops.dev != dev)
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continue;
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found = true;
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break;
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}
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return found;
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}
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static void nft_dev_forward_path(struct nf_flow_route *route,
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const struct nf_conn *ct,
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enum ip_conntrack_dir dir,
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struct nft_flowtable *ft)
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{
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const struct dst_entry *dst = route->tuple[dir].dst;
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struct net_device_path_stack stack;
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struct nft_forward_info info = {};
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unsigned char ha[ETH_ALEN];
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int i;
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if (nft_dev_fill_forward_path(route, dst, ct, dir, ha, &stack) >= 0)
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nft_dev_path_info(&stack, &info, ha, &ft->data);
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if (!info.indev || !nft_flowtable_find_dev(info.indev, ft))
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return;
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route->tuple[!dir].in.ifindex = info.indev->ifindex;
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for (i = 0; i < info.num_encaps; i++) {
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route->tuple[!dir].in.encap[i].id = info.encap[i].id;
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route->tuple[!dir].in.encap[i].proto = info.encap[i].proto;
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}
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route->tuple[!dir].in.num_encaps = info.num_encaps;
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route->tuple[!dir].in.ingress_vlans = info.ingress_vlans;
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if (info.xmit_type == FLOW_OFFLOAD_XMIT_DIRECT) {
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memcpy(route->tuple[dir].out.h_source, info.h_source, ETH_ALEN);
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memcpy(route->tuple[dir].out.h_dest, info.h_dest, ETH_ALEN);
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route->tuple[dir].out.ifindex = info.outdev->ifindex;
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route->tuple[dir].out.hw_ifindex = info.hw_outdev->ifindex;
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route->tuple[dir].xmit_type = info.xmit_type;
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}
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}
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static int nft_flow_route(const struct nft_pktinfo *pkt,
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const struct nf_conn *ct,
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struct nf_flow_route *route,
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enum ip_conntrack_dir dir,
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struct nft_flowtable *ft)
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{
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struct dst_entry *this_dst = skb_dst(pkt->skb);
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struct dst_entry *other_dst = NULL;
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struct flowi fl;
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memset(&fl, 0, sizeof(fl));
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switch (nft_pf(pkt)) {
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case NFPROTO_IPV4:
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fl.u.ip4.daddr = ct->tuplehash[dir].tuple.src.u3.ip;
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fl.u.ip4.saddr = ct->tuplehash[!dir].tuple.src.u3.ip;
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fl.u.ip4.flowi4_oif = nft_in(pkt)->ifindex;
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fl.u.ip4.flowi4_iif = this_dst->dev->ifindex;
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fl.u.ip4.flowi4_tos = RT_TOS(ip_hdr(pkt->skb)->tos);
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fl.u.ip4.flowi4_mark = pkt->skb->mark;
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fl.u.ip4.flowi4_flags = FLOWI_FLAG_ANYSRC;
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break;
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case NFPROTO_IPV6:
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fl.u.ip6.daddr = ct->tuplehash[dir].tuple.src.u3.in6;
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fl.u.ip6.saddr = ct->tuplehash[!dir].tuple.src.u3.in6;
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fl.u.ip6.flowi6_oif = nft_in(pkt)->ifindex;
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fl.u.ip6.flowi6_iif = this_dst->dev->ifindex;
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fl.u.ip6.flowlabel = ip6_flowinfo(ipv6_hdr(pkt->skb));
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fl.u.ip6.flowi6_mark = pkt->skb->mark;
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fl.u.ip6.flowi6_flags = FLOWI_FLAG_ANYSRC;
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break;
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}
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if (!dst_hold_safe(this_dst))
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return -ENOENT;
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nf_route(nft_net(pkt), &other_dst, &fl, false, nft_pf(pkt));
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if (!other_dst) {
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dst_release(this_dst);
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return -ENOENT;
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}
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nft_default_forward_path(route, this_dst, dir);
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nft_default_forward_path(route, other_dst, !dir);
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if (route->tuple[dir].xmit_type == FLOW_OFFLOAD_XMIT_NEIGH &&
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route->tuple[!dir].xmit_type == FLOW_OFFLOAD_XMIT_NEIGH) {
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nft_dev_forward_path(route, ct, dir, ft);
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nft_dev_forward_path(route, ct, !dir, ft);
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}
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return 0;
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}
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static bool nft_flow_offload_skip(struct sk_buff *skb, int family)
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{
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if (skb_sec_path(skb))
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return true;
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if (family == NFPROTO_IPV4) {
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const struct ip_options *opt;
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opt = &(IPCB(skb)->opt);
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if (unlikely(opt->optlen))
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return true;
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}
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return false;
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}
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static void nft_flow_offload_eval(const struct nft_expr *expr,
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struct nft_regs *regs,
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const struct nft_pktinfo *pkt)
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{
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struct nft_flow_offload *priv = nft_expr_priv(expr);
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struct nf_flowtable *flowtable = &priv->flowtable->data;
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struct tcphdr _tcph, *tcph = NULL;
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struct nf_flow_route route = {};
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enum ip_conntrack_info ctinfo;
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struct flow_offload *flow;
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enum ip_conntrack_dir dir;
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struct nf_conn *ct;
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int ret;
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if (nft_flow_offload_skip(pkt->skb, nft_pf(pkt)))
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goto out;
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ct = nf_ct_get(pkt->skb, &ctinfo);
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if (!ct)
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goto out;
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switch (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum) {
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case IPPROTO_TCP:
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tcph = skb_header_pointer(pkt->skb, nft_thoff(pkt),
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sizeof(_tcph), &_tcph);
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if (unlikely(!tcph || tcph->fin || tcph->rst ||
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!nf_conntrack_tcp_established(ct)))
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goto out;
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break;
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case IPPROTO_UDP:
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break;
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#ifdef CONFIG_NF_CT_PROTO_GRE
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case IPPROTO_GRE: {
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struct nf_conntrack_tuple *tuple;
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if (ct->status & IPS_NAT_MASK)
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goto out;
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tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
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/* No support for GRE v1 */
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if (tuple->src.u.gre.key || tuple->dst.u.gre.key)
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goto out;
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break;
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}
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#endif
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default:
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goto out;
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}
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if (nf_ct_ext_exist(ct, NF_CT_EXT_HELPER) ||
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ct->status & (IPS_SEQ_ADJUST | IPS_NAT_CLASH))
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goto out;
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if (!nf_ct_is_confirmed(ct))
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goto out;
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if (test_and_set_bit(IPS_OFFLOAD_BIT, &ct->status))
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goto out;
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dir = CTINFO2DIR(ctinfo);
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if (nft_flow_route(pkt, ct, &route, dir, priv->flowtable) < 0)
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goto err_flow_route;
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flow = flow_offload_alloc(ct);
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if (!flow)
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goto err_flow_alloc;
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flow_offload_route_init(flow, &route);
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if (tcph) {
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ct->proto.tcp.seen[0].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
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ct->proto.tcp.seen[1].flags |= IP_CT_TCP_FLAG_BE_LIBERAL;
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}
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ret = flow_offload_add(flowtable, flow);
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if (ret < 0)
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goto err_flow_add;
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return;
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err_flow_add:
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flow_offload_free(flow);
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err_flow_alloc:
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dst_release(route.tuple[dir].dst);
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dst_release(route.tuple[!dir].dst);
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err_flow_route:
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clear_bit(IPS_OFFLOAD_BIT, &ct->status);
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out:
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regs->verdict.code = NFT_BREAK;
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}
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static int nft_flow_offload_validate(const struct nft_ctx *ctx,
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const struct nft_expr *expr,
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const struct nft_data **data)
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{
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unsigned int hook_mask = (1 << NF_INET_FORWARD);
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return nft_chain_validate_hooks(ctx->chain, hook_mask);
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}
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static const struct nla_policy nft_flow_offload_policy[NFTA_FLOW_MAX + 1] = {
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[NFTA_FLOW_TABLE_NAME] = { .type = NLA_STRING,
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.len = NFT_NAME_MAXLEN - 1 },
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};
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static int nft_flow_offload_init(const struct nft_ctx *ctx,
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const struct nft_expr *expr,
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const struct nlattr * const tb[])
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{
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struct nft_flow_offload *priv = nft_expr_priv(expr);
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u8 genmask = nft_genmask_next(ctx->net);
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struct nft_flowtable *flowtable;
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if (!tb[NFTA_FLOW_TABLE_NAME])
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return -EINVAL;
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flowtable = nft_flowtable_lookup(ctx->table, tb[NFTA_FLOW_TABLE_NAME],
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genmask);
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if (IS_ERR(flowtable))
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return PTR_ERR(flowtable);
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if (!nft_use_inc(&flowtable->use))
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return -EMFILE;
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priv->flowtable = flowtable;
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return nf_ct_netns_get(ctx->net, ctx->family);
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}
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static void nft_flow_offload_deactivate(const struct nft_ctx *ctx,
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const struct nft_expr *expr,
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enum nft_trans_phase phase)
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{
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struct nft_flow_offload *priv = nft_expr_priv(expr);
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nf_tables_deactivate_flowtable(ctx, priv->flowtable, phase);
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}
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static void nft_flow_offload_activate(const struct nft_ctx *ctx,
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const struct nft_expr *expr)
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{
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struct nft_flow_offload *priv = nft_expr_priv(expr);
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nft_use_inc_restore(&priv->flowtable->use);
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}
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static void nft_flow_offload_destroy(const struct nft_ctx *ctx,
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const struct nft_expr *expr)
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{
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nf_ct_netns_put(ctx->net, ctx->family);
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}
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static int nft_flow_offload_dump(struct sk_buff *skb,
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const struct nft_expr *expr, bool reset)
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{
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struct nft_flow_offload *priv = nft_expr_priv(expr);
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if (nla_put_string(skb, NFTA_FLOW_TABLE_NAME, priv->flowtable->name))
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goto nla_put_failure;
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return 0;
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nla_put_failure:
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return -1;
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}
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static struct nft_expr_type nft_flow_offload_type;
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static const struct nft_expr_ops nft_flow_offload_ops = {
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.type = &nft_flow_offload_type,
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.size = NFT_EXPR_SIZE(sizeof(struct nft_flow_offload)),
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.eval = nft_flow_offload_eval,
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.init = nft_flow_offload_init,
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.activate = nft_flow_offload_activate,
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.deactivate = nft_flow_offload_deactivate,
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.destroy = nft_flow_offload_destroy,
|
|
.validate = nft_flow_offload_validate,
|
|
.dump = nft_flow_offload_dump,
|
|
.reduce = NFT_REDUCE_READONLY,
|
|
};
|
|
|
|
static struct nft_expr_type nft_flow_offload_type __read_mostly = {
|
|
.name = "flow_offload",
|
|
.ops = &nft_flow_offload_ops,
|
|
.policy = nft_flow_offload_policy,
|
|
.maxattr = NFTA_FLOW_MAX,
|
|
.owner = THIS_MODULE,
|
|
};
|
|
|
|
static int flow_offload_netdev_event(struct notifier_block *this,
|
|
unsigned long event, void *ptr)
|
|
{
|
|
struct net_device *dev = netdev_notifier_info_to_dev(ptr);
|
|
|
|
if (event != NETDEV_DOWN)
|
|
return NOTIFY_DONE;
|
|
|
|
nf_flow_table_cleanup(dev);
|
|
|
|
return NOTIFY_DONE;
|
|
}
|
|
|
|
static struct notifier_block flow_offload_netdev_notifier = {
|
|
.notifier_call = flow_offload_netdev_event,
|
|
};
|
|
|
|
static int __init nft_flow_offload_module_init(void)
|
|
{
|
|
int err;
|
|
|
|
err = register_netdevice_notifier(&flow_offload_netdev_notifier);
|
|
if (err)
|
|
goto err;
|
|
|
|
err = nft_register_expr(&nft_flow_offload_type);
|
|
if (err < 0)
|
|
goto register_expr;
|
|
|
|
return 0;
|
|
|
|
register_expr:
|
|
unregister_netdevice_notifier(&flow_offload_netdev_notifier);
|
|
err:
|
|
return err;
|
|
}
|
|
|
|
static void __exit nft_flow_offload_module_exit(void)
|
|
{
|
|
nft_unregister_expr(&nft_flow_offload_type);
|
|
unregister_netdevice_notifier(&flow_offload_netdev_notifier);
|
|
}
|
|
|
|
module_init(nft_flow_offload_module_init);
|
|
module_exit(nft_flow_offload_module_exit);
|
|
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
|
|
MODULE_ALIAS_NFT_EXPR("flow_offload");
|
|
MODULE_DESCRIPTION("nftables hardware flow offload module");
|