Add new bpf_skb_adjust_room() decapsulation flags: - BPF_F_ADJ_ROOM_DECAP_L4_GRE - BPF_F_ADJ_ROOM_DECAP_L4_UDP - BPF_F_ADJ_ROOM_DECAP_IPXIP4 - BPF_F_ADJ_ROOM_DECAP_IPXIP6 These flags let BPF programs describe which tunnel layer is being removed, so later changes can update tunnel-related GSO state accordingly during decapsulation. This patch only introduces the UAPI flag definitions and helper documentation. Co-developed-by: Max Tottenham <mtottenh@akamai.com> Co-developed-by: Anna Glasgall <aglasgal@akamai.com> Signed-off-by: Max Tottenham <mtottenh@akamai.com> Signed-off-by: Anna Glasgall <aglasgal@akamai.com> Signed-off-by: Nick Hudson <nhudson@akamai.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Willem de Bruijn <willemb@google.com> Link: https://lore.kernel.org/bpf/20260812083115.73100-4-nhudson@akamai.com
The existing anonymous enum for BPF_FUNC_skb_adjust_room flags is named to enum bpf_adj_room_flags to enable CO-RE (Compile Once - Run Everywhere) lookups in BPF programs. Co-developed-by: Max Tottenham <mtottenh@akamai.com> Co-developed-by: Anna Glasgall <aglasgal@akamai.com> Signed-off-by: Max Tottenham <mtottenh@akamai.com> Signed-off-by: Anna Glasgall <aglasgal@akamai.com> Signed-off-by: Nick Hudson <nhudson@akamai.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Willem de Bruijn <willemb@google.com> Link: https://lore.kernel.org/bpf/20260812083115.73100-2-nhudson@akamai.com
BPF_RB_OVERWRITE_POS is supported by bpf_ringbuf_query() but was missing from the helper documentation. Add it to the flags list in both the kernel UAPI header and its tools/ mirror. Signed-off-by: Jianlin Shi <shijianlin11@foxmail.com> Acked-by: Xu Kuohai <xukuohai@huawei.com> Link: https://lore.kernel.org/bpf/tencent_22134645443B75ED907D2A85A47AD554A709@qq.com Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
BPF_FIB_LOOKUP_VLAN resolves a VLAN egress. The reverse is also useful: an XDP program receiving a VLAN-tagged frame on a physical device wants the lookup to behave as if the packet had arrived on the corresponding VLAN subinterface, so iif-based policy routing and VRF table selection use the right ingress. Add BPF_FIB_LOOKUP_VLAN_INPUT. When set, params->h_vlan_proto and params->h_vlan_TCI are read as an input VLAN tag and the matching VLAN device of params->ifindex is resolved with __vlan_find_dev_deep_rcu(). The device must be up and in the same network namespace as params->ifindex (a VLAN device can be moved to another netns while registered on its parent; receive would deliver into that other namespace, which a lookup here cannot represent). If params->ifindex is itself a VLAN device, its inner (QinQ) subinterface is matched. For a bond or team, a tag on a port matches no device and returns NOT_FWDED; pass the master's ifindex. The lookup then runs with the resolved device as the ingress; params->ifindex itself is not modified on the input side. When the resolved device is enslaved to a VRF, both the full lookup (via the l3mdev rule) and BPF_FIB_LOOKUP_DIRECT (via l3mdev_fib_table_rcu()) select the VRF's table from the resolved ingress. That follows from feeding the resolved device to the flow as the ingress (fl4.flowi4_iif = dev->ifindex), which is what makes l3mdev resolve the VRF master from the subinterface rather than from params->ifindex. The two failure classes get different treatment on purpose. A h_vlan_proto other than 802.1Q/802.1ad is API misuse and returns -EINVAL, since it would otherwise reach the WARN in vlan_proto_idx() with a program-controlled value. An unmatched VID, a device that is down, or one in another namespace is a data outcome and returns BPF_FIB_LKUP_RET_NOT_FWDED, matching the DIRECT path when fib_get_table() finds no table and mirroring real ingress, where the receive path drops such frames. A VID of 0 (a priority tag) is looked up literally and normally fails the same way; receive instead processes such frames untagged, so callers should not set the flag for priority tags. Proceeding on the physical device for any of these would be fail-open for the policy-routing cases above. The h_vlan fields share a union with tbid, so the flag cannot be combined with BPF_FIB_LOOKUP_TBID. It describes ingress, so it also cannot be combined with BPF_FIB_LOOKUP_OUTPUT. Both combinations return -EINVAL; restricting now keeps a later relaxation backward compatible. Combining with BPF_FIB_LOOKUP_VLAN is allowed: the tag is consumed on the ingress side and the egress tag is written on success. Under !CONFIG_VLAN_8021Q the __vlan_find_dev_deep_rcu() stub returns NULL, so every lookup with a valid proto returns NOT_FWDED, which is correct since no VLAN device can exist. Suggested-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Avinash Duduskar <avinash.duduskar@gmail.com> Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com> Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com> Link: https://lore.kernel.org/bpf/20260713162305.1237211-3-avinash.duduskar@gmail.com Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
bpf_fib_lookup() returns the FIB-resolved egress ifindex straight from the fib result. When the egress is a VLAN device, the returned ifindex is the VLAN netdev's, which has no XDP xmit handler; XDP programs that want to forward the frame (e.g. xdp-forward) must instead target the underlying physical device and push the VLAN tag themselves. Today the program has no way to learn either the underlying ifindex or the VLAN tag without maintaining its own VLAN-to-ifindex map in userspace and refreshing it on netlink events. Add BPF_FIB_LOOKUP_VLAN. When the caller sets this flag and the fib result is a VLAN device whose immediate parent is a real (non-VLAN) device in the same network namespace, populate the existing output fields params->h_vlan_proto and params->h_vlan_TCI from the VLAN device and replace params->ifindex with the parent's ifindex. params->h_vlan_TCI carries the VID only, with PCP and DEI bits zero; a consumer wanting to set egress priority writes PCP itself. params->smac is the VLAN device's own address, which can differ from the parent's. Only the immediate parent is resolved, via vlan_dev_priv(dev)->real_dev and not vlan_dev_real_dev(), which walks to the bottom of a stack. When the immediate parent is not a real device in the same namespace, the lookup returns BPF_FIB_LKUP_RET_VLAN_FAILURE and leaves params->ifindex at the input. This covers a stacked VLAN (QinQ), where the immediate parent is itself a VLAN device and one h_vlan_proto/h_vlan_TCI pair cannot describe two tags, and a parent in another network namespace (a VLAN device can be moved while its parent stays), whose ifindex would be meaningless in the caller's namespace. A program that wants the VLAN device's own ifindex re-issues the lookup, with a re-initialized params, without BPF_FIB_LOOKUP_VLAN, so the unreducible case stays distinct from a physical egress. That distinction matters for XDP: a program cannot xmit on a VLAN device, so a success carrying the VLAN ifindex would make it redirect to a device with no ndo_xdp_xmit and drop the frame at xdp_do_flush(). The swap and the vlan fields are written only on the reduce path; other output fields keep their existing behaviour, so a frag-needed result still reports the route mtu in params->mtu_result. BPF_FIB_LOOKUP_VLAN is only useful to XDP, which cannot redirect to a VLAN device. A tc program can redirect to the VLAN device directly, so bpf_skb_fib_lookup() rejects the flag with -EINVAL; bpf_xdp_fib_lookup() accepts it. When the flag is not set, behaviour is unchanged: h_vlan_proto and h_vlan_TCI are zeroed and ifindex is left at the FIB result. The new block is compiled only under CONFIG_VLAN_8021Q since vlan_dev_priv() is not defined otherwise; without that config is_vlan_dev() is constant false and the flag is accepted but never acts. That is safe because no VLAN device can exist there, so every egress is already physical. This lets an XDP redirect target the physical device and learn the tag to push in a single lookup, which xdp-forward's optional VLAN mode (xdp-project/xdp-tools#504) wants from the kernel side. The helper's input semantics are unchanged; the reverse direction (supplying a tag as lookup input) is added in the following patch. Suggested-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Avinash Duduskar <avinash.duduskar@gmail.com> Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com> Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com> Acked-by: David Ahern <dsahern@kernel.org> Link: https://lore.kernel.org/bpf/20260713162305.1237211-2-avinash.duduskar@gmail.com Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Adding BPF_OBJ_GET_INFO_BY_FD support for tracing_multi links. We expose following tracing_multi link data: - attach_type of the program - number of ids - array of BTF ids - array of its related kernel addresses - array of cookies The change follows the kprobe_multi and uprobe_multi link-info convention of optional output arrays with an in/out count, On top of standard tracing link data we also expose addresses, because they are useful info for user (especially when the attachment was done via pattern). This data is hidden when kallsyms does not allow exposing kernel pointer values. Assisted-by: Codex:GPT-5 Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Leon Hwang <leon.hwang@linux.dev> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20260629212208.895962-2-jolsa@kernel.org
We have several use cases where a pod injects traffic into the datapath of another so that the traffic appears to have originated from that pod. One such use case is a synthetic flow generator which injects synthetic traffic into a pod's datapath to enable dynamic probing and debugging. Another is a transparent proxy where connections originating from one pod are redirected towards another which proxies that connection. The new connection is bound to the IP of the original pod using IP_TRANSPARENT and its traffic is injected into that pod's datapath and handled as if it had originated there. This can be used for mTLS, etc. We use bpf_redirect(BPF_F_INGRESS) to direct traffic leaving the proxy, flow generator, etc. towards the target pod, ensuring that eBPF programs that are meant to intercept traffic leaving that pod are executed. However, this doesn't work with netkit. With netkit, an ingress redirection from proxy to workload skips eBPF programs that are meant to intercept traffic leaving the pod, since they reside on the netkit peer device. One workaround is to attach the same program to both the netkit peer device and the TCX ingress hook for the netkit pair's primary interface, but a) This seems hacky and we need to be careful not to run the same program twice for the same skb in cases where we want to pass that traffic to the host stack. b) We're trying to keep the proxy redirection / traffic injection systems as modular and separated from Cilium as possible, the system that manages netkit setup and core eBPF programming. It would be handy if instead we could redirect traffic directly from one netkit peer device to another. This patch proposes an extension to bpf_redirect_peer to allow us to do just that. With this patch, the BPF_F_EGRESS flag tells bpf_redirect_peer to emit the skb in the egress direction of the target interface's peer device While the main use case is netkit, I suppose you could also use this mode with veth as well if, e.g., there were some eBPF programs attached to that side of the veth pair that needed to intercept traffic. +---------------------------------------------------------------------+ | +-------------------------+ 6. bpf_redirect_neigh(eth0) | | | pod (10.244.0.10) | ------------------------ | | | | | | | | | +--------+ | | +---------+ | | | | 1. packet -->| | | | | | | | | | leaves ^ | netkit |<===========|======| netkit | | | | | | | peer |=======(eBPF)=====>| primary | | | | | | | | | | | | | | | | | +--------+ | | +---------+ | | | | | | | 2. bpf_redirect v | | +-----------|-------------+ |___________________ +-------| | | | | eth0 | | | 5. bpf_redirect_peer(BPF_F_EGRESS) | +-------| | |________________________ | | | +-------------------------+ | | | | | proxy (10.244.0.11) | | | | | | IP_TRANSPARENT | | | | | | +--------+ | | +---------+ | | | | 3. packet <--| | | | | |<-- | | | enters | netkit |<===========|======| netkit | | | | [proxy] | peer |=======(eBPF)=====>| primary | | | | 4. packet -->| | | | | | | | leaves +--------+ | +---------+ | | | sip=10.244.0.10 | | | +-------------------------+ | +---------------------------------------------------------------------+ Using the proxy use case as an example, in step 5 we would redirect traffic leaving the proxy towards the pod's peer device using bpf_redirect_peer(BPF_F_EGRESS). As a bonus, since the skb doesn't have to go through the backlog queue it can take full advantage of netkit's performance benefits. I set up a test where outgoing iperf3 traffic is injected into the datapath of another pod using either bpf_redirect_peer(BPF_F_EGRESS) or bpf_redirect(BPF_F_INGRESS). I used Cilium's eBPF host routing mode which skips the host stack and uses BPF redirect helpers to do all the routing. (net.ipv4.tcp_congestion_control=cubic,mtu=1500,100GiB link,Cilium eBPF host routing mode) BASELINE [bpf_redirect(BPF_F_INGRESS)] 1. [iperf pod] ==bpf_redirect([pod b], BPF_F_INGRESS)==> [pod b] 2. [pod b] ==bpf_redirect_neigh([eth0])==> eth0 3. eth0 ==over network==> [host b] [ ID] Interval Transfer Bitrate Retr [ 5] 0.00-60.00 sec 231 GBytes 33.0 Gbits/sec 12060 sender [ 5] 0.00-60.00 sec 230 GBytes 33.0 Gbits/sec receiver TEST [bpf_redirect_peer(BPF_F_EGRESS)] 1. [iperf pod] ==bpf_redirect_peer([pod b], BPF_F_EGRESS)==> [pod b] 2. [pod b] ==bpf_redirect_neigh([eth0])==> eth0 3. eth0 ==over network==> [host b] [ ID] Interval Transfer Bitrate Retr [ 5] 0.00-60.00 sec 272 GBytes 38.9 Gbits/sec 0 sender [ 5] 0.00-60.00 sec 272 GBytes 38.9 Gbits/sec receiver In this test, using bpf_redirect_peer(BPF_F_EGRESS) for the hop from [iperf pod] to [pod b] led to ~18% more throughput compared to bpf_redirect(BPF_F_INGRESS). Signed-off-by: Jordan Rife <jordan@jrife.io> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Paul Chaignon <paul.chaignon@gmail.com> Reviewed-by: Jiayuan Chen <jiayuan.chen@linux.dev> Link: https://lore.kernel.org/r/20260618182035.43811-2-jordan@jrife.io Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Allow uprobe_multi link to identify the target binary by an already opened file descriptor. Adding new BPF_F_UPROBE_MULTI_PATH_FD flag and the path_fd field for the attr.link_create.uprobe_multi struct. When the flag is set, we resolve the target from path_fd, without the flag, we keep the existing string path behavior. I don't see a use case for supporting O_PATH file descriptors, because we need to read the binary first to get probes offsets, so I'm using the CLASS(fd, f), which fails for O_PATH fds. Assisted-by: Codex:GPT-5.4 Signed-off-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/r/20260611114230.950379-4-jolsa@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Adding support to use session attachment with tracing_multi link. Adding new BPF_TRACE_FSESSION_MULTI program attach type, that follows the BPF_TRACE_FSESSION behaviour but on the tracing_multi link. Such program is called on entry and exit of the attached function and allows to pass cookie value from entry to exit execution. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/r/20260606123955.345967-16-jolsa@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add support to specify cookies for tracing_multi link. Cookies are provided in array where each value is paired with provided BTF ID value with the same array index. Such cookie can be retrieved by bpf program with bpf_get_attach_cookie helper call. We need to sort cookies array together with ids array in check_dup_ids, to keep the id->cookie relation. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/r/20260606123955.345967-15-jolsa@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>