diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c index 87d361666cdd..3b39def5471e 100644 --- a/drivers/net/loopback.c +++ b/drivers/net/loopback.c @@ -55,6 +55,13 @@ #include #include +/* blackhole_netdev - a device used for dsts that are marked expired! + * This is global device (instead of per-net-ns) since it's not needed + * to be per-ns and gets initialized at boot time. + */ +struct net_device *blackhole_netdev; +EXPORT_SYMBOL(blackhole_netdev); + /* The higher levels take care of making this non-reentrant (it's * called with bh's disabled). */ @@ -150,12 +157,14 @@ static const struct net_device_ops loopback_ops = { .ndo_set_mac_address = eth_mac_addr, }; -/* The loopback device is special. There is only one instance - * per network namespace. - */ -static void loopback_setup(struct net_device *dev) +static void gen_lo_setup(struct net_device *dev, + unsigned int mtu, + const struct ethtool_ops *eth_ops, + const struct header_ops *hdr_ops, + const struct net_device_ops *dev_ops, + void (*dev_destructor)(struct net_device *dev)) { - dev->mtu = 64 * 1024; + dev->mtu = mtu; dev->hard_header_len = ETH_HLEN; /* 14 */ dev->min_header_len = ETH_HLEN; /* 14 */ dev->addr_len = ETH_ALEN; /* 6 */ @@ -174,11 +183,20 @@ static void loopback_setup(struct net_device *dev) | NETIF_F_NETNS_LOCAL | NETIF_F_VLAN_CHALLENGED | NETIF_F_LOOPBACK; - dev->ethtool_ops = &loopback_ethtool_ops; - dev->header_ops = ð_header_ops; - dev->netdev_ops = &loopback_ops; + dev->ethtool_ops = eth_ops; + dev->header_ops = hdr_ops; + dev->netdev_ops = dev_ops; dev->needs_free_netdev = true; - dev->priv_destructor = loopback_dev_free; + dev->priv_destructor = dev_destructor; +} + +/* The loopback device is special. There is only one instance + * per network namespace. + */ +static void loopback_setup(struct net_device *dev) +{ + gen_lo_setup(dev, (64 * 1024), &loopback_ethtool_ops, ð_header_ops, + &loopback_ops, loopback_dev_free); } /* Setup and register the loopback device. */ @@ -213,3 +231,43 @@ out: struct pernet_operations __net_initdata loopback_net_ops = { .init = loopback_net_init, }; + +/* blackhole netdevice */ +static netdev_tx_t blackhole_netdev_xmit(struct sk_buff *skb, + struct net_device *dev) +{ + kfree_skb(skb); + net_warn_ratelimited("%s(): Dropping skb.\n", __func__); + return NETDEV_TX_OK; +} + +static const struct net_device_ops blackhole_netdev_ops = { + .ndo_start_xmit = blackhole_netdev_xmit, +}; + +/* This is a dst-dummy device used specifically for invalidated + * DSTs and unlike loopback, this is not per-ns. + */ +static void blackhole_netdev_setup(struct net_device *dev) +{ + gen_lo_setup(dev, ETH_MIN_MTU, NULL, NULL, &blackhole_netdev_ops, NULL); +} + +/* Setup and register the blackhole_netdev. */ +static int __init blackhole_netdev_init(void) +{ + blackhole_netdev = alloc_netdev(0, "blackhole_dev", NET_NAME_UNKNOWN, + blackhole_netdev_setup); + if (!blackhole_netdev) + return -ENOMEM; + + dev_init_scheduler(blackhole_netdev); + dev_activate(blackhole_netdev); + + blackhole_netdev->flags |= IFF_UP | IFF_RUNNING; + dev_net_set(blackhole_netdev, &init_net); + + return 0; +} + +device_initcall(blackhole_netdev_init); diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index eeacebd7debb..88292953aa6f 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -4870,4 +4870,6 @@ do { \ #define PTYPE_HASH_SIZE (16) #define PTYPE_HASH_MASK (PTYPE_HASH_SIZE - 1) +extern struct net_device *blackhole_netdev; + #endif /* _LINUX_NETDEVICE_H */ diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index cbdfae379896..99272b5dd980 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1909,6 +1909,15 @@ config TEST_BPF If unsure, say N. +config TEST_BLACKHOLE_DEV + tristate "Test blackhole netdev functionality" + depends on m && NET + help + This builds the "test_blackhole_dev" module that validates the + data path through this blackhole netdev. + + If unsure, say N. + config FIND_BIT_BENCHMARK tristate "Test find_bit functions" help diff --git a/lib/Makefile b/lib/Makefile index dcb558c7554d..6ac44fe2a37f 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -91,6 +91,7 @@ obj-$(CONFIG_TEST_DEBUG_VIRTUAL) += test_debug_virtual.o obj-$(CONFIG_TEST_MEMCAT_P) += test_memcat_p.o obj-$(CONFIG_TEST_OBJAGG) += test_objagg.o obj-$(CONFIG_TEST_STACKINIT) += test_stackinit.o +obj-$(CONFIG_TEST_BLACKHOLE_DEV) += test_blackhole_dev.o obj-$(CONFIG_TEST_LIVEPATCH) += livepatch/ diff --git a/lib/test_blackhole_dev.c b/lib/test_blackhole_dev.c new file mode 100644 index 000000000000..4c40580a99a3 --- /dev/null +++ b/lib/test_blackhole_dev.c @@ -0,0 +1,100 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * This module tests the blackhole_dev that is created during the + * net subsystem initialization. The test this module performs is + * by injecting an skb into the stack with skb->dev as the + * blackhole_dev and expects kernel to behave in a sane manner + * (in other words, *not crash*)! + * + * Copyright (c) 2018, Mahesh Bandewar + */ + +#include +#include +#include +#include +#include +#include +#include + +#include + +#define SKB_SIZE 256 +#define HEAD_SIZE (14+40+8) /* Ether + IPv6 + UDP */ +#define TAIL_SIZE 32 /* random tail-room */ + +#define UDP_PORT 1234 + +static int __init test_blackholedev_init(void) +{ + struct ipv6hdr *ip6h; + struct sk_buff *skb; + struct ethhdr *ethh; + struct udphdr *uh; + int data_len; + int ret; + + skb = alloc_skb(SKB_SIZE, GFP_KERNEL); + if (!skb) + return -ENOMEM; + + /* Reserve head-room for the headers */ + skb_reserve(skb, HEAD_SIZE); + + /* Add data to the skb */ + data_len = SKB_SIZE - (HEAD_SIZE + TAIL_SIZE); + memset(__skb_put(skb, data_len), 0xf, data_len); + + /* Add protocol data */ + /* (Transport) UDP */ + uh = (struct udphdr *)skb_push(skb, sizeof(struct udphdr)); + skb_set_transport_header(skb, 0); + uh->source = uh->dest = htons(UDP_PORT); + uh->len = htons(data_len); + uh->check = 0; + /* (Network) IPv6 */ + ip6h = (struct ipv6hdr *)skb_push(skb, sizeof(struct ipv6hdr)); + skb_set_network_header(skb, 0); + ip6h->hop_limit = 32; + ip6h->payload_len = data_len + sizeof(struct udphdr); + ip6h->nexthdr = IPPROTO_UDP; + ip6h->saddr = in6addr_loopback; + ip6h->daddr = in6addr_loopback; + /* Ether */ + ethh = (struct ethhdr *)skb_push(skb, sizeof(struct ethhdr)); + skb_set_mac_header(skb, 0); + + skb->protocol = htons(ETH_P_IPV6); + skb->pkt_type = PACKET_HOST; + skb->dev = blackhole_netdev; + + /* Now attempt to send the packet */ + ret = dev_queue_xmit(skb); + + switch (ret) { + case NET_XMIT_SUCCESS: + pr_warn("dev_queue_xmit() returned NET_XMIT_SUCCESS\n"); + break; + case NET_XMIT_DROP: + pr_warn("dev_queue_xmit() returned NET_XMIT_DROP\n"); + break; + case NET_XMIT_CN: + pr_warn("dev_queue_xmit() returned NET_XMIT_CN\n"); + break; + default: + pr_err("dev_queue_xmit() returned UNKNOWN(%d)\n", ret); + } + + return 0; +} + +static void __exit test_blackholedev_exit(void) +{ + pr_warn("test_blackholedev module terminating.\n"); +} + +module_init(test_blackholedev_init); +module_exit(test_blackholedev_exit); + +MODULE_AUTHOR("Mahesh Bandewar "); +MODULE_LICENSE("GPL"); diff --git a/net/core/dst.c b/net/core/dst.c index e46366228eaf..1325316d9eab 100644 --- a/net/core/dst.c +++ b/net/core/dst.c @@ -160,7 +160,7 @@ void dst_dev_put(struct dst_entry *dst) dst->ops->ifdown(dst, dev, true); dst->input = dst_discard; dst->output = dst_discard_out; - dst->dev = dev_net(dst->dev)->loopback_dev; + dst->dev = blackhole_netdev; dev_hold(dst->dev); dev_put(dev); } diff --git a/net/ipv4/route.c b/net/ipv4/route.c index bbd55c7f6b2e..dc1f510a7c81 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1532,7 +1532,6 @@ static void ipv4_dst_destroy(struct dst_entry *dst) void rt_flush_dev(struct net_device *dev) { - struct net *net = dev_net(dev); struct rtable *rt; int cpu; @@ -1543,7 +1542,7 @@ void rt_flush_dev(struct net_device *dev) list_for_each_entry(rt, &ul->head, rt_uncached) { if (rt->dst.dev != dev) continue; - rt->dst.dev = net->loopback_dev; + rt->dst.dev = blackhole_netdev; dev_hold(rt->dst.dev); dev_put(dev); } diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 7556275b1cef..39361f57351a 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -176,7 +176,7 @@ static void rt6_uncached_list_flush_dev(struct net *net, struct net_device *dev) } if (rt_dev == dev) { - rt->dst.dev = loopback_dev; + rt->dst.dev = blackhole_netdev; dev_hold(rt->dst.dev); dev_put(rt_dev); } diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile index 9a275d932fd5..1b24e36b4047 100644 --- a/tools/testing/selftests/net/Makefile +++ b/tools/testing/selftests/net/Makefile @@ -5,7 +5,7 @@ CFLAGS = -Wall -Wl,--no-as-needed -O2 -g CFLAGS += -I../../../../usr/include/ TEST_PROGS := run_netsocktests run_afpackettests test_bpf.sh netdevice.sh \ - rtnetlink.sh xfrm_policy.sh + rtnetlink.sh xfrm_policy.sh test_blackhole_dev.sh TEST_PROGS += fib_tests.sh fib-onlink-tests.sh pmtu.sh udpgso.sh ip_defrag.sh TEST_PROGS += udpgso_bench.sh fib_rule_tests.sh msg_zerocopy.sh psock_snd.sh TEST_PROGS += udpgro_bench.sh udpgro.sh test_vxlan_under_vrf.sh reuseport_addr_any.sh diff --git a/tools/testing/selftests/net/config b/tools/testing/selftests/net/config index 89f84b5118bf..e4b878d95ba0 100644 --- a/tools/testing/selftests/net/config +++ b/tools/testing/selftests/net/config @@ -27,3 +27,4 @@ CONFIG_NFT_CHAIN_NAT_IPV6=m CONFIG_NFT_CHAIN_NAT_IPV4=m CONFIG_NET_SCH_FQ=m CONFIG_NET_SCH_ETF=m +CONFIG_TEST_BLACKHOLE_DEV=m diff --git a/tools/testing/selftests/net/test_blackhole_dev.sh b/tools/testing/selftests/net/test_blackhole_dev.sh new file mode 100755 index 000000000000..3119b80e711f --- /dev/null +++ b/tools/testing/selftests/net/test_blackhole_dev.sh @@ -0,0 +1,11 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# Runs blackhole-dev test using blackhole-dev kernel module + +if /sbin/modprobe -q test_blackhole_dev ; then + /sbin/modprobe -q -r test_blackhole_dev; + echo "test_blackhole_dev: ok"; +else + echo "test_blackhole_dev: [FAIL]"; + exit 1; +fi