bpf: don't use bpf_redirect_neigh() from overlay programs#42000
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julianwiedmann merged 3 commits intomainfrom Oct 6, 2025
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bpf: don't use bpf_redirect_neigh() from overlay programs#42000julianwiedmann merged 3 commits intomainfrom
julianwiedmann merged 3 commits intomainfrom
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mcast.h by accident pulls in common.h, but before the various file-wide defines like IS_BPF_OVERLAY are set. This makes them unusable in places like overloadable_skb.h. Fix things up making common.h the first regular header that gets included, as done in all other programs. For this also shuffle the tailcall.h further down, even though it's currently harmless. Signed-off-by: Julian Wiedmann <jwi@isovalent.com>
This reverts commit 3c1b39a. For the following patch we need to tolerate that bpf_redirect_neigh() is not available when egress_gw_fib_lookup_and_redirect_v*() is called from inside bpf_overlay. Signed-off-by: Julian Wiedmann <jwi@isovalent.com>
Yusuke chased down a kernel bug [0] that causes memory leaks when bpf_redirect_neigh() is called from bpf_overlay. As work-around we can opt-out from using the helper, and going down the fallback path in the callers (eg treating it like a call from XDP context). [0]: https://lore.kernel.org/netdev/20251003073418.291171-1-daniel@iogearbox.net/T/#u Reported-by: Yusuke Suzuki <yusuke.suzuki@isovalent.com> Signed-off-by: Julian Wiedmann <jwi@isovalent.com>
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I'm tempted to add a fine-grained |
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/test |
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#42000 limited the usage of bpf_redirect_neigh() from overlay programs, to work-around a kernel bug that causes a memory leak. This bug only manifests when bpf_redirect_neigh() is called without next-hop information - or in Cilium terms, without a preceding FIB lookup. By annotating such specific usage of bpf_redirect_neigh() with a fine-grained capability check, we can otherwise allow the use of bpf_redirect_neigh() from overlay context. Start by introducing the neigh_resolver_without_nh_available() check in all relevant places. Signed-off-by: Julian Wiedmann <jwi@isovalent.com>
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Started this in #42052. |
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#42000 limited the usage of bpf_redirect_neigh() from overlay programs, to work-around a kernel bug that causes a memory leak. This bug only manifests when bpf_redirect_neigh() is called without next-hop information - or in Cilium terms, without a preceding FIB lookup. By annotating such specific usage of bpf_redirect_neigh() with a fine-grained capability check, we can otherwise allow the use of bpf_redirect_neigh() from overlay context. Start by introducing the neigh_resolver_without_nh_available() check in all relevant places. Signed-off-by: Julian Wiedmann <jwi@isovalent.com>
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#42000 limited the usage of bpf_redirect_neigh() from overlay programs, to work-around a kernel bug that causes a memory leak. This bug only manifests when bpf_redirect_neigh() is called without next-hop information - or in Cilium terms, without a preceding FIB lookup. By annotating such specific usage of bpf_redirect_neigh() with a fine-grained capability check, we can otherwise allow the use of bpf_redirect_neigh() from overlay context. Start by introducing the neigh_resolver_without_nh_available() check in all relevant places. Signed-off-by: Julian Wiedmann <jwi@isovalent.com>
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cilium#42000 limited the usage of bpf_redirect_neigh() from overlay programs, to work-around a kernel bug that causes a memory leak. This bug only manifests when bpf_redirect_neigh() is called without next-hop information - or in Cilium terms, without a preceding FIB lookup. By annotating such specific usage of bpf_redirect_neigh() with a fine-grained capability check, we can otherwise allow the use of bpf_redirect_neigh() from overlay context. Start by introducing the neigh_resolver_without_nh_available() check in all relevant places. Signed-off-by: Julian Wiedmann <jwi@isovalent.com>
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Yusuke chased down a kernel bug 0 that causes memory leaks when bpf_redirect_neigh() is called from bpf_overlay.
As work-around we can opt-out from using the helper, and going down the fallback path in the callers (eg treating it like a call from XDP context).