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dab4e1f06c
Extend the bpf_fib_lookup() helper by making it to return the source
IPv4/IPv6 address if the BPF_FIB_LOOKUP_SRC flag is set.
For example, the following snippet can be used to derive the desired
source IP address:
struct bpf_fib_lookup p = { .ipv4_dst = ip4->daddr };
ret = bpf_skb_fib_lookup(skb, p, sizeof(p),
BPF_FIB_LOOKUP_SRC | BPF_FIB_LOOKUP_SKIP_NEIGH);
if (ret != BPF_FIB_LKUP_RET_SUCCESS)
return TC_ACT_SHOT;
/* the p.ipv4_src now contains the source address */
The inability to derive the proper source address may cause malfunctions
in BPF-based dataplanes for hosts containing netdevs with more than one
routable IP address or for multi-homed hosts.
For example, Cilium implements packet masquerading in BPF. If an
egressing netdev to which the Cilium's BPF prog is attached has
multiple IP addresses, then only one [hardcoded] IP address can be used for
masquerading. This breaks connectivity if any other IP address should have
been selected instead, for example, when a public and private addresses
are attached to the same egress interface.
The change was tested with Cilium [1].
Nikolay Aleksandrov helped to figure out the IPv6 addr selection.
[1]: https://github.com/cilium/cilium/pull/28283
Signed-off-by: Martynas Pumputis <m@lambda.lt>
Link: https://lore.kernel.org/r/20231007081415.33502-2-m@lambda.lt
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
97 lines
3.6 KiB
C
97 lines
3.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _IPV6_STUBS_H
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#define _IPV6_STUBS_H
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#include <linux/in6.h>
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#include <linux/netdevice.h>
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#include <linux/skbuff.h>
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#include <net/dst.h>
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#include <net/flow.h>
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#include <net/neighbour.h>
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#include <net/sock.h>
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/* structs from net/ip6_fib.h */
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struct fib6_info;
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struct fib6_nh;
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struct fib6_config;
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struct fib6_result;
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/* This is ugly, ideally these symbols should be built
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* into the core kernel.
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*/
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struct ipv6_stub {
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int (*ipv6_sock_mc_join)(struct sock *sk, int ifindex,
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const struct in6_addr *addr);
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int (*ipv6_sock_mc_drop)(struct sock *sk, int ifindex,
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const struct in6_addr *addr);
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struct dst_entry *(*ipv6_dst_lookup_flow)(struct net *net,
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const struct sock *sk,
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struct flowi6 *fl6,
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const struct in6_addr *final_dst);
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int (*ipv6_route_input)(struct sk_buff *skb);
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struct fib6_table *(*fib6_get_table)(struct net *net, u32 id);
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int (*fib6_lookup)(struct net *net, int oif, struct flowi6 *fl6,
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struct fib6_result *res, int flags);
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int (*fib6_table_lookup)(struct net *net, struct fib6_table *table,
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int oif, struct flowi6 *fl6,
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struct fib6_result *res, int flags);
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void (*fib6_select_path)(const struct net *net, struct fib6_result *res,
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struct flowi6 *fl6, int oif, bool oif_match,
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const struct sk_buff *skb, int strict);
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u32 (*ip6_mtu_from_fib6)(const struct fib6_result *res,
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const struct in6_addr *daddr,
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const struct in6_addr *saddr);
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int (*fib6_nh_init)(struct net *net, struct fib6_nh *fib6_nh,
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struct fib6_config *cfg, gfp_t gfp_flags,
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struct netlink_ext_ack *extack);
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void (*fib6_nh_release)(struct fib6_nh *fib6_nh);
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void (*fib6_nh_release_dsts)(struct fib6_nh *fib6_nh);
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void (*fib6_update_sernum)(struct net *net, struct fib6_info *rt);
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int (*ip6_del_rt)(struct net *net, struct fib6_info *rt, bool skip_notify);
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void (*fib6_rt_update)(struct net *net, struct fib6_info *rt,
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struct nl_info *info);
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void (*udpv6_encap_enable)(void);
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void (*ndisc_send_na)(struct net_device *dev, const struct in6_addr *daddr,
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const struct in6_addr *solicited_addr,
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bool router, bool solicited, bool override, bool inc_opt);
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#if IS_ENABLED(CONFIG_XFRM)
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void (*xfrm6_local_rxpmtu)(struct sk_buff *skb, u32 mtu);
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int (*xfrm6_udp_encap_rcv)(struct sock *sk, struct sk_buff *skb);
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int (*xfrm6_rcv_encap)(struct sk_buff *skb, int nexthdr, __be32 spi,
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int encap_type);
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#endif
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struct neigh_table *nd_tbl;
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int (*ipv6_fragment)(struct net *net, struct sock *sk, struct sk_buff *skb,
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int (*output)(struct net *, struct sock *, struct sk_buff *));
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struct net_device *(*ipv6_dev_find)(struct net *net, const struct in6_addr *addr,
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struct net_device *dev);
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};
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extern const struct ipv6_stub *ipv6_stub __read_mostly;
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/* A stub used by bpf helpers. Similarly ugly as ipv6_stub */
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struct ipv6_bpf_stub {
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int (*inet6_bind)(struct sock *sk, struct sockaddr *uaddr, int addr_len,
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u32 flags);
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struct sock *(*udp6_lib_lookup)(struct net *net,
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const struct in6_addr *saddr, __be16 sport,
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const struct in6_addr *daddr, __be16 dport,
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int dif, int sdif, struct udp_table *tbl,
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struct sk_buff *skb);
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int (*ipv6_setsockopt)(struct sock *sk, int level, int optname,
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sockptr_t optval, unsigned int optlen);
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int (*ipv6_getsockopt)(struct sock *sk, int level, int optname,
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sockptr_t optval, sockptr_t optlen);
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int (*ipv6_dev_get_saddr)(struct net *net,
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const struct net_device *dst_dev,
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const struct in6_addr *daddr,
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unsigned int prefs,
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struct in6_addr *saddr);
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};
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extern const struct ipv6_bpf_stub *ipv6_bpf_stub __read_mostly;
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#endif
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