Martynas Pumputis b96f500dbb bpf: Derive source IP addr via bpf_*_fib_lookup() ... commit dab4e1f06c upstream. 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> Cc: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2024-03-01 13:35:04 +01:00
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asm	tools headers: Update the copy of x86's mem{cpy,set}_64.S used in 'perf bench'	2023-05-17 10:42:19 -03:00
asm-generic	tools: KVM: selftests: Convert clear/set_bit() to actual atomics	2022-12-02 13:22:35 -05:00
linux	work around gcc bugs with 'asm goto' with outputs	2024-02-23 09:24:47 +01:00
nolibc	tools/nolibc: mark start_c as weak	2023-10-12 21:13:51 +02:00
tools	tools include: add dis-asm-compat.h to handle version differences	2022-08-01 15:29:49 -03:00
trace/events
uapi	bpf: Derive source IP addr via bpf_*_fib_lookup()	2024-03-01 13:35:04 +01:00
vdso	tools headers: Synchronize {linux,vdso}/bits.h with the kernel sources	2023-03-03 22:34:15 -03:00