From ba452c9e996d8a4c347b32805f91abb70de5de7e Mon Sep 17 00:00:00 2001 From: =?utf8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= Date: Tue, 20 Oct 2020 23:25:56 +0200 Subject: [PATCH] bpf: Fix bpf_redirect_neigh helper api to support supplying nexthop MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Based on the discussion in [0], update the bpf_redirect_neigh() helper to accept an optional parameter specifying the nexthop information. This makes it possible to combine bpf_fib_lookup() and bpf_redirect_neigh() without incurring a duplicate FIB lookup - since the FIB lookup helper will return the nexthop information even if no neighbour is present, this can simply be passed on to bpf_redirect_neigh() if bpf_fib_lookup() returns BPF_FIB_LKUP_RET_NO_NEIGH. Thus fix & extend it before helper API is frozen. [0] https://lore.kernel.org/bpf/393e17fc-d187-3a8d-2f0d-a627c7c63fca@iogearbox.net/ Signed-off-by: Toke Høiland-Jørgensen Signed-off-by: Daniel Borkmann Reviewed-by: David Ahern Link: https://lore.kernel.org/bpf/160322915615.32199.1187570224032024535.stgit@toke.dk --- include/linux/filter.h | 9 +++ include/uapi/linux/bpf.h | 22 ++++-- net/core/filter.c | 158 ++++++++++++++++++++++++++--------------- scripts/bpf_helpers_doc.py | 1 + tools/include/uapi/linux/bpf.h | 22 ++++-- 5 files changed, 145 insertions(+), 67 deletions(-) diff --git a/include/linux/filter.h b/include/linux/filter.h index 20fc24c..72d62cb 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -607,12 +607,21 @@ struct bpf_skb_data_end { void *data_end; }; +struct bpf_nh_params { + u32 nh_family; + union { + u32 ipv4_nh; + struct in6_addr ipv6_nh; + }; +}; + struct bpf_redirect_info { u32 flags; u32 tgt_index; void *tgt_value; struct bpf_map *map; u32 kern_flags; + struct bpf_nh_params nh; }; DECLARE_PER_CPU(struct bpf_redirect_info, bpf_redirect_info); diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index bf5a99d..e6ceac3 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -3677,15 +3677,19 @@ union bpf_attr { * Return * The id is returned or 0 in case the id could not be retrieved. * - * long bpf_redirect_neigh(u32 ifindex, u64 flags) + * long bpf_redirect_neigh(u32 ifindex, struct bpf_redir_neigh *params, int plen, u64 flags) * Description * Redirect the packet to another net device of index *ifindex* * and fill in L2 addresses from neighboring subsystem. This helper * is somewhat similar to **bpf_redirect**\ (), except that it * populates L2 addresses as well, meaning, internally, the helper - * performs a FIB lookup based on the skb's networking header to - * get the address of the next hop and then relies on the neighbor - * lookup for the L2 address of the nexthop. + * relies on the neighbor lookup for the L2 address of the nexthop. + * + * The helper will perform a FIB lookup based on the skb's + * networking header to get the address of the next hop, unless + * this is supplied by the caller in the *params* argument. The + * *plen* argument indicates the len of *params* and should be set + * to 0 if *params* is NULL. * * The *flags* argument is reserved and must be 0. The helper is * currently only supported for tc BPF program types, and enabled @@ -4906,6 +4910,16 @@ struct bpf_fib_lookup { __u8 dmac[6]; /* ETH_ALEN */ }; +struct bpf_redir_neigh { + /* network family for lookup (AF_INET, AF_INET6) */ + __u32 nh_family; + /* network address of nexthop; skips fib lookup to find gateway */ + union { + __be32 ipv4_nh; + __u32 ipv6_nh[4]; /* in6_addr; network order */ + }; +}; + enum bpf_task_fd_type { BPF_FD_TYPE_RAW_TRACEPOINT, /* tp name */ BPF_FD_TYPE_TRACEPOINT, /* tp name */ diff --git a/net/core/filter.c b/net/core/filter.c index c5e2a1c..6d0fa65 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2165,12 +2165,12 @@ static int __bpf_redirect(struct sk_buff *skb, struct net_device *dev, } #if IS_ENABLED(CONFIG_IPV6) -static int bpf_out_neigh_v6(struct net *net, struct sk_buff *skb) +static int bpf_out_neigh_v6(struct net *net, struct sk_buff *skb, + struct net_device *dev, struct bpf_nh_params *nh) { - struct dst_entry *dst = skb_dst(skb); - struct net_device *dev = dst->dev; u32 hh_len = LL_RESERVED_SPACE(dev); const struct in6_addr *nexthop; + struct dst_entry *dst = NULL; struct neighbour *neigh; if (dev_xmit_recursion()) { @@ -2196,8 +2196,13 @@ static int bpf_out_neigh_v6(struct net *net, struct sk_buff *skb) } rcu_read_lock_bh(); - nexthop = rt6_nexthop(container_of(dst, struct rt6_info, dst), - &ipv6_hdr(skb)->daddr); + if (!nh) { + dst = skb_dst(skb); + nexthop = rt6_nexthop(container_of(dst, struct rt6_info, dst), + &ipv6_hdr(skb)->daddr); + } else { + nexthop = &nh->ipv6_nh; + } neigh = ip_neigh_gw6(dev, nexthop); if (likely(!IS_ERR(neigh))) { int ret; @@ -2210,36 +2215,43 @@ static int bpf_out_neigh_v6(struct net *net, struct sk_buff *skb) return ret; } rcu_read_unlock_bh(); - IP6_INC_STATS(dev_net(dst->dev), - ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES); + if (dst) + IP6_INC_STATS(dev_net(dst->dev), + ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES); out_drop: kfree_skb(skb); return -ENETDOWN; } -static int __bpf_redirect_neigh_v6(struct sk_buff *skb, struct net_device *dev) +static int __bpf_redirect_neigh_v6(struct sk_buff *skb, struct net_device *dev, + struct bpf_nh_params *nh) { const struct ipv6hdr *ip6h = ipv6_hdr(skb); struct net *net = dev_net(dev); int err, ret = NET_XMIT_DROP; - struct dst_entry *dst; - struct flowi6 fl6 = { - .flowi6_flags = FLOWI_FLAG_ANYSRC, - .flowi6_mark = skb->mark, - .flowlabel = ip6_flowinfo(ip6h), - .flowi6_oif = dev->ifindex, - .flowi6_proto = ip6h->nexthdr, - .daddr = ip6h->daddr, - .saddr = ip6h->saddr, - }; - dst = ipv6_stub->ipv6_dst_lookup_flow(net, NULL, &fl6, NULL); - if (IS_ERR(dst)) - goto out_drop; + if (!nh) { + struct dst_entry *dst; + struct flowi6 fl6 = { + .flowi6_flags = FLOWI_FLAG_ANYSRC, + .flowi6_mark = skb->mark, + .flowlabel = ip6_flowinfo(ip6h), + .flowi6_oif = dev->ifindex, + .flowi6_proto = ip6h->nexthdr, + .daddr = ip6h->daddr, + .saddr = ip6h->saddr, + }; + + dst = ipv6_stub->ipv6_dst_lookup_flow(net, NULL, &fl6, NULL); + if (IS_ERR(dst)) + goto out_drop; - skb_dst_set(skb, dst); + skb_dst_set(skb, dst); + } else if (nh->nh_family != AF_INET6) { + goto out_drop; + } - err = bpf_out_neigh_v6(net, skb); + err = bpf_out_neigh_v6(net, skb, dev, nh); if (unlikely(net_xmit_eval(err))) dev->stats.tx_errors++; else @@ -2252,7 +2264,8 @@ out_xmit: return ret; } #else -static int __bpf_redirect_neigh_v6(struct sk_buff *skb, struct net_device *dev) +static int __bpf_redirect_neigh_v6(struct sk_buff *skb, struct net_device *dev, + struct bpf_nh_params *nh) { kfree_skb(skb); return NET_XMIT_DROP; @@ -2260,11 +2273,9 @@ static int __bpf_redirect_neigh_v6(struct sk_buff *skb, struct net_device *dev) #endif /* CONFIG_IPV6 */ #if IS_ENABLED(CONFIG_INET) -static int bpf_out_neigh_v4(struct net *net, struct sk_buff *skb) +static int bpf_out_neigh_v4(struct net *net, struct sk_buff *skb, + struct net_device *dev, struct bpf_nh_params *nh) { - struct dst_entry *dst = skb_dst(skb); - struct rtable *rt = container_of(dst, struct rtable, dst); - struct net_device *dev = dst->dev; u32 hh_len = LL_RESERVED_SPACE(dev); struct neighbour *neigh; bool is_v6gw = false; @@ -2292,7 +2303,21 @@ static int bpf_out_neigh_v4(struct net *net, struct sk_buff *skb) } rcu_read_lock_bh(); - neigh = ip_neigh_for_gw(rt, skb, &is_v6gw); + if (!nh) { + struct dst_entry *dst = skb_dst(skb); + struct rtable *rt = container_of(dst, struct rtable, dst); + + neigh = ip_neigh_for_gw(rt, skb, &is_v6gw); + } else if (nh->nh_family == AF_INET6) { + neigh = ip_neigh_gw6(dev, &nh->ipv6_nh); + is_v6gw = true; + } else if (nh->nh_family == AF_INET) { + neigh = ip_neigh_gw4(dev, nh->ipv4_nh); + } else { + rcu_read_unlock_bh(); + goto out_drop; + } + if (likely(!IS_ERR(neigh))) { int ret; @@ -2309,33 +2334,37 @@ out_drop: return -ENETDOWN; } -static int __bpf_redirect_neigh_v4(struct sk_buff *skb, struct net_device *dev) +static int __bpf_redirect_neigh_v4(struct sk_buff *skb, struct net_device *dev, + struct bpf_nh_params *nh) { const struct iphdr *ip4h = ip_hdr(skb); struct net *net = dev_net(dev); int err, ret = NET_XMIT_DROP; - struct rtable *rt; - struct flowi4 fl4 = { - .flowi4_flags = FLOWI_FLAG_ANYSRC, - .flowi4_mark = skb->mark, - .flowi4_tos = RT_TOS(ip4h->tos), - .flowi4_oif = dev->ifindex, - .flowi4_proto = ip4h->protocol, - .daddr = ip4h->daddr, - .saddr = ip4h->saddr, - }; - rt = ip_route_output_flow(net, &fl4, NULL); - if (IS_ERR(rt)) - goto out_drop; - if (rt->rt_type != RTN_UNICAST && rt->rt_type != RTN_LOCAL) { - ip_rt_put(rt); - goto out_drop; - } + if (!nh) { + struct flowi4 fl4 = { + .flowi4_flags = FLOWI_FLAG_ANYSRC, + .flowi4_mark = skb->mark, + .flowi4_tos = RT_TOS(ip4h->tos), + .flowi4_oif = dev->ifindex, + .flowi4_proto = ip4h->protocol, + .daddr = ip4h->daddr, + .saddr = ip4h->saddr, + }; + struct rtable *rt; + + rt = ip_route_output_flow(net, &fl4, NULL); + if (IS_ERR(rt)) + goto out_drop; + if (rt->rt_type != RTN_UNICAST && rt->rt_type != RTN_LOCAL) { + ip_rt_put(rt); + goto out_drop; + } - skb_dst_set(skb, &rt->dst); + skb_dst_set(skb, &rt->dst); + } - err = bpf_out_neigh_v4(net, skb); + err = bpf_out_neigh_v4(net, skb, dev, nh); if (unlikely(net_xmit_eval(err))) dev->stats.tx_errors++; else @@ -2348,14 +2377,16 @@ out_xmit: return ret; } #else -static int __bpf_redirect_neigh_v4(struct sk_buff *skb, struct net_device *dev) +static int __bpf_redirect_neigh_v4(struct sk_buff *skb, struct net_device *dev, + struct bpf_nh_params *nh) { kfree_skb(skb); return NET_XMIT_DROP; } #endif /* CONFIG_INET */ -static int __bpf_redirect_neigh(struct sk_buff *skb, struct net_device *dev) +static int __bpf_redirect_neigh(struct sk_buff *skb, struct net_device *dev, + struct bpf_nh_params *nh) { struct ethhdr *ethh = eth_hdr(skb); @@ -2370,9 +2401,9 @@ static int __bpf_redirect_neigh(struct sk_buff *skb, struct net_device *dev) skb_reset_network_header(skb); if (skb->protocol == htons(ETH_P_IP)) - return __bpf_redirect_neigh_v4(skb, dev); + return __bpf_redirect_neigh_v4(skb, dev, nh); else if (skb->protocol == htons(ETH_P_IPV6)) - return __bpf_redirect_neigh_v6(skb, dev); + return __bpf_redirect_neigh_v6(skb, dev, nh); out: kfree_skb(skb); return -ENOTSUPP; @@ -2382,7 +2413,8 @@ out: enum { BPF_F_NEIGH = (1ULL << 1), BPF_F_PEER = (1ULL << 2), -#define BPF_F_REDIRECT_INTERNAL (BPF_F_NEIGH | BPF_F_PEER) + BPF_F_NEXTHOP = (1ULL << 3), +#define BPF_F_REDIRECT_INTERNAL (BPF_F_NEIGH | BPF_F_PEER | BPF_F_NEXTHOP) }; BPF_CALL_3(bpf_clone_redirect, struct sk_buff *, skb, u32, ifindex, u64, flags) @@ -2455,7 +2487,8 @@ int skb_do_redirect(struct sk_buff *skb) return -EAGAIN; } return flags & BPF_F_NEIGH ? - __bpf_redirect_neigh(skb, dev) : + __bpf_redirect_neigh(skb, dev, flags & BPF_F_NEXTHOP ? + &ri->nh : NULL) : __bpf_redirect(skb, dev, flags); out_drop: kfree_skb(skb); @@ -2504,16 +2537,21 @@ static const struct bpf_func_proto bpf_redirect_peer_proto = { .arg2_type = ARG_ANYTHING, }; -BPF_CALL_2(bpf_redirect_neigh, u32, ifindex, u64, flags) +BPF_CALL_4(bpf_redirect_neigh, u32, ifindex, struct bpf_redir_neigh *, params, + int, plen, u64, flags) { struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info); - if (unlikely(flags)) + if (unlikely((plen && plen < sizeof(*params)) || flags)) return TC_ACT_SHOT; - ri->flags = BPF_F_NEIGH; + ri->flags = BPF_F_NEIGH | (plen ? BPF_F_NEXTHOP : 0); ri->tgt_index = ifindex; + BUILD_BUG_ON(sizeof(struct bpf_redir_neigh) != sizeof(struct bpf_nh_params)); + if (plen) + memcpy(&ri->nh, params, sizeof(ri->nh)); + return TC_ACT_REDIRECT; } @@ -2522,7 +2560,9 @@ static const struct bpf_func_proto bpf_redirect_neigh_proto = { .gpl_only = false, .ret_type = RET_INTEGER, .arg1_type = ARG_ANYTHING, - .arg2_type = ARG_ANYTHING, + .arg2_type = ARG_PTR_TO_MEM_OR_NULL, + .arg3_type = ARG_CONST_SIZE_OR_ZERO, + .arg4_type = ARG_ANYTHING, }; BPF_CALL_2(bpf_msg_apply_bytes, struct sk_msg *, msg, u32, bytes) diff --git a/scripts/bpf_helpers_doc.py b/scripts/bpf_helpers_doc.py index 7d86fdd..6769caa 100755 --- a/scripts/bpf_helpers_doc.py +++ b/scripts/bpf_helpers_doc.py @@ -453,6 +453,7 @@ class PrinterHelpers(Printer): 'struct bpf_perf_event_data', 'struct bpf_perf_event_value', 'struct bpf_pidns_info', + 'struct bpf_redir_neigh', 'struct bpf_sk_lookup', 'struct bpf_sock', 'struct bpf_sock_addr', diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index bf5a99d..e6ceac3 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -3677,15 +3677,19 @@ union bpf_attr { * Return * The id is returned or 0 in case the id could not be retrieved. * - * long bpf_redirect_neigh(u32 ifindex, u64 flags) + * long bpf_redirect_neigh(u32 ifindex, struct bpf_redir_neigh *params, int plen, u64 flags) * Description * Redirect the packet to another net device of index *ifindex* * and fill in L2 addresses from neighboring subsystem. This helper * is somewhat similar to **bpf_redirect**\ (), except that it * populates L2 addresses as well, meaning, internally, the helper - * performs a FIB lookup based on the skb's networking header to - * get the address of the next hop and then relies on the neighbor - * lookup for the L2 address of the nexthop. + * relies on the neighbor lookup for the L2 address of the nexthop. + * + * The helper will perform a FIB lookup based on the skb's + * networking header to get the address of the next hop, unless + * this is supplied by the caller in the *params* argument. The + * *plen* argument indicates the len of *params* and should be set + * to 0 if *params* is NULL. * * The *flags* argument is reserved and must be 0. The helper is * currently only supported for tc BPF program types, and enabled @@ -4906,6 +4910,16 @@ struct bpf_fib_lookup { __u8 dmac[6]; /* ETH_ALEN */ }; +struct bpf_redir_neigh { + /* network family for lookup (AF_INET, AF_INET6) */ + __u32 nh_family; + /* network address of nexthop; skips fib lookup to find gateway */ + union { + __be32 ipv4_nh; + __u32 ipv6_nh[4]; /* in6_addr; network order */ + }; +}; + enum bpf_task_fd_type { BPF_FD_TYPE_RAW_TRACEPOINT, /* tp name */ BPF_FD_TYPE_TRACEPOINT, /* tp name */ -- 2.7.4