* [PATCH bpf-next v4 0/3] bpf: bidirectional VLAN support for bpf_fib_lookup()
@ 2026-06-23 2:51 Avinash Duduskar
2026-06-23 2:51 ` [PATCH bpf-next v4 1/3] bpf: Add BPF_FIB_LOOKUP_VLAN flag to bpf_fib_lookup() helper Avinash Duduskar
` (2 more replies)
0 siblings, 3 replies; 10+ messages in thread
From: Avinash Duduskar @ 2026-06-23 2:51 UTC (permalink / raw)
To: ast, daniel, andrii
Cc: eddyz87, memxor, martin.lau, song, yonghong.song, jolsa, emil,
john.fastabend, sdf, davem, edumazet, kuba, pabeni, horms, shuah,
hawk, yatsenko, leon.hwang, kpsingh, a.s.protopopov, ameryhung,
rongtao, eyal.birger, bpf, netdev, linux-kernel, linux-kselftest,
toke, dsahern
This series adds VLAN awareness to bpf_fib_lookup() in both directions.
BPF_FIB_LOOKUP_VLAN resolves a VLAN egress to its underlying real device
plus the VLAN tag (XDP programs need this because VLAN devices have no XDP
xmit), and BPF_FIB_LOOKUP_VLAN_INPUT runs the lookup as if a tagged frame
had arrived on the matching VLAN subinterface, for iif policy routing and
VRF table selection.
The independent l3mdev/VRF flow-init fix, patch 1 in v1 and v2, was split
out and merged to bpf separately.
v4 changes what bpf_fib_lookup() returns in one case. v3 left a VLAN
egress that cannot be reduced to a physical device plus one tag (a QinQ
egress, or a parent in another namespace) as best-effort SUCCESS with
the VLAN device's ifindex. In his v3 review Toke asked for a distinct
error code there instead, so an XDP program cannot mistake an unresolved
VLAN egress for a physical one, and suggested the name
BPF_FIB_LKUP_RET_VLAN_FAILURE; v4 implements that. The
code is appended after BPF_FIB_LKUP_RET_NO_SRC_ADDR (nothing renumbered,
tools/ mirror updated) and is returned only when BPF_FIB_LOOKUP_VLAN is
set, so no existing caller can observe it. On that failure params->ifindex
is left at the input, like the input-side failures; a tc or XDP program
that wants the VLAN device's own ifindex re-issues the lookup without the
flag, the recovery path he described.
The reason for a distinct code rather than best-effort SUCCESS: SUCCESS
on an unreducible egress silently blackholed XDP. A redirect to the VLAN
device drops at xdp_do_flush() with no in-band signal to the program;
VLAN_FAILURE makes the unreducible case explicit, and a live-frames
selftest exercises both the redirected and the passed paths. Only the
immediate parent is resolved, so QinQ and foreign-netns are the
unreducible cases; bond, team, TBID and VRF egress resolve, as the
selftest table pins.
Changes v3 -> v4:
- Patch 1: return BPF_FIB_LKUP_RET_VLAN_FAILURE for an unreducible VLAN
egress, leaving params->ifindex at the input.
- Patch 3: the QinQ-egress and cross-namespace-egress arms expect
VLAN_FAILURE; an escape-hatch arm re-issues without the flag for the
inner VLAN device's ifindex; and test_fib_lookup_vlan_redirect drives
live frames (BPF_F_TEST_XDP_LIVE_FRAMES) through the native redirect
path, asserting a reducible egress is delivered and a QinQ egress is
passed to the stack. The selftest's VLAN_FAILURE arms are IPv4 only,
since bpf_ipv6_fib_lookup() restores params->ifindex with the same code
as the IPv4 path that the arms exercise.
The three other v3 questions Toke marked fine as-is, and v4 keeps them: an
unmatched, down, or cross-namespace tag on input returns NOT_FWDED;
OUTPUT | VLAN_INPUT is rejected with -EINVAL; the BPF_FIB_LOOKUP_VLAN_INPUT
name is kept.
Taking the tag as lookup input follows the approach David Ahern suggested
in the 2021 fwmark discussion:
https://lore.kernel.org/bpf/6248c547-ad64-04d6-fcec-374893cc1ef2@gmail.com/
v3: https://lore.kernel.org/all/20260617224729.1428662-1-avinash.duduskar@gmail.com/
v2: https://lore.kernel.org/all/20260616223426.3568080-1-avinash.duduskar@gmail.com/
v1: https://lore.kernel.org/all/20260609172052.81613-1-avinash.duduskar@gmail.com/
Avinash Duduskar (3):
bpf: Add BPF_FIB_LOOKUP_VLAN flag to bpf_fib_lookup() helper
bpf: Add BPF_FIB_LOOKUP_VLAN_INPUT flag to bpf_fib_lookup() helper
selftests/bpf: Add bpf_fib_lookup() VLAN flag tests
include/uapi/linux/bpf.h | 47 +-
net/core/filter.c | 133 +++-
tools/include/uapi/linux/bpf.h | 47 +-
.../selftests/bpf/prog_tests/fib_lookup.c | 696 +++++++++++++++++-
.../testing/selftests/bpf/progs/fib_lookup.c | 36 +
5 files changed, 930 insertions(+), 29 deletions(-)
base-commit: a975094bf98ca97be9146f9d3b5681a6f9cf5ce3
--
2.54.0
^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH bpf-next v4 1/3] bpf: Add BPF_FIB_LOOKUP_VLAN flag to bpf_fib_lookup() helper
2026-06-23 2:51 [PATCH bpf-next v4 0/3] bpf: bidirectional VLAN support for bpf_fib_lookup() Avinash Duduskar
@ 2026-06-23 2:51 ` Avinash Duduskar
2026-06-23 11:58 ` Toke Høiland-Jørgensen
2026-06-23 2:51 ` [PATCH bpf-next v4 2/3] bpf: Add BPF_FIB_LOOKUP_VLAN_INPUT " Avinash Duduskar
2026-06-23 2:51 ` [PATCH bpf-next v4 3/3] selftests/bpf: Add bpf_fib_lookup() VLAN flag tests Avinash Duduskar
2 siblings, 1 reply; 10+ messages in thread
From: Avinash Duduskar @ 2026-06-23 2:51 UTC (permalink / raw)
To: ast, daniel, andrii
Cc: eddyz87, memxor, martin.lau, song, yonghong.song, jolsa, emil,
john.fastabend, sdf, davem, edumazet, kuba, pabeni, horms, shuah,
hawk, yatsenko, leon.hwang, kpsingh, a.s.protopopov, ameryhung,
rongtao, eyal.birger, bpf, netdev, linux-kernel, linux-kselftest,
toke, dsahern
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 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.
On the skb path without tot_len the deferred mtu check is done against
the resolved egress device. To keep that the VLAN device rather than
the parent after the swap, bpf_ipv4_fib_lookup()/bpf_ipv6_fib_lookup()
hand the FIB-result device back to the caller; the XDP path always
runs the route-mtu check and passes NULL. 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>
---
include/uapi/linux/bpf.h | 28 +++++++++++++-
net/core/filter.c | 69 ++++++++++++++++++++++++----------
tools/include/uapi/linux/bpf.h | 28 +++++++++++++-
3 files changed, 104 insertions(+), 21 deletions(-)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 89b36de5fdbb..8d0058d88eb2 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -3532,6 +3532,26 @@ union bpf_attr {
* Use the mark present in *params*->mark for the fib lookup.
* This option should not be used with BPF_FIB_LOOKUP_DIRECT,
* as it only has meaning for full lookups.
+ * **BPF_FIB_LOOKUP_VLAN**
+ * If the fib lookup resolves to a VLAN device whose
+ * parent is a real (non-VLAN) device, set
+ * *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; if it
+ * is itself a VLAN device (QinQ) or in another namespace,
+ * the egress cannot be reduced to a physical device plus
+ * one tag and the lookup returns
+ * **BPF_FIB_LKUP_RET_VLAN_FAILURE** with *params*->ifindex
+ * left at the input. Re-issue without
+ * **BPF_FIB_LOOKUP_VLAN** to obtain the VLAN device's own
+ * ifindex. The swap and the vlan fields
+ * are written only on success; other output fields keep
+ * the helper's existing behaviour, so a frag-needed result
+ * still reports the route mtu in *params*->mtu_result.
*
* *ctx* is either **struct xdp_md** for XDP programs or
* **struct sk_buff** tc cls_act programs.
@@ -7327,6 +7347,7 @@ enum {
BPF_FIB_LOOKUP_TBID = (1U << 3),
BPF_FIB_LOOKUP_SRC = (1U << 4),
BPF_FIB_LOOKUP_MARK = (1U << 5),
+ BPF_FIB_LOOKUP_VLAN = (1U << 6),
};
enum {
@@ -7340,6 +7361,7 @@ enum {
BPF_FIB_LKUP_RET_NO_NEIGH, /* no neighbor entry for nh */
BPF_FIB_LKUP_RET_FRAG_NEEDED, /* fragmentation required to fwd */
BPF_FIB_LKUP_RET_NO_SRC_ADDR, /* failed to derive IP src addr */
+ BPF_FIB_LKUP_RET_VLAN_FAILURE, /* VLAN egress, parent unresolvable */
};
struct bpf_fib_lookup {
@@ -7393,7 +7415,11 @@ struct bpf_fib_lookup {
union {
struct {
- /* output */
+ /*
+ * output with BPF_FIB_LOOKUP_VLAN: set from the
+ * resolved egress VLAN device (see the flag); zeroed
+ * on other successful lookups.
+ */
__be16 h_vlan_proto;
__be16 h_vlan_TCI;
};
diff --git a/net/core/filter.c b/net/core/filter.c
index 2e96b4b847ce..8345295d84de 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -6201,10 +6201,28 @@ static const struct bpf_func_proto bpf_skb_get_xfrm_state_proto = {
#endif
#if IS_ENABLED(CONFIG_INET) || IS_ENABLED(CONFIG_IPV6)
-static int bpf_fib_set_fwd_params(struct bpf_fib_lookup *params, u32 mtu)
+static int bpf_fib_set_fwd_params(struct net_device *dev,
+ struct bpf_fib_lookup *params,
+ u32 flags, u32 mtu)
{
params->h_vlan_TCI = 0;
params->h_vlan_proto = 0;
+
+#if IS_ENABLED(CONFIG_VLAN_8021Q)
+ if ((flags & BPF_FIB_LOOKUP_VLAN) && is_vlan_dev(dev)) {
+ struct net_device *real_dev = vlan_dev_priv(dev)->real_dev;
+
+ if (!is_vlan_dev(real_dev) &&
+ net_eq(dev_net(real_dev), dev_net(dev))) {
+ params->h_vlan_proto = vlan_dev_vlan_proto(dev);
+ params->h_vlan_TCI = htons(vlan_dev_vlan_id(dev));
+ params->ifindex = real_dev->ifindex;
+ } else {
+ return BPF_FIB_LKUP_RET_VLAN_FAILURE;
+ }
+ }
+#endif
+
if (mtu)
params->mtu_result = mtu; /* union with tot_len */
@@ -6214,8 +6232,10 @@ static int bpf_fib_set_fwd_params(struct bpf_fib_lookup *params, u32 mtu)
#if IS_ENABLED(CONFIG_INET)
static int bpf_ipv4_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
- u32 flags, bool check_mtu)
+ u32 flags, bool check_mtu,
+ struct net_device **fwd_dev)
{
+ u32 in_ifindex = params->ifindex;
struct neighbour *neigh = NULL;
struct fib_nh_common *nhc;
struct in_device *in_dev;
@@ -6347,16 +6367,23 @@ static int bpf_ipv4_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
memcpy(params->smac, dev->dev_addr, ETH_ALEN);
set_fwd_params:
- return bpf_fib_set_fwd_params(params, mtu);
+ if (fwd_dev)
+ *fwd_dev = dev;
+ err = bpf_fib_set_fwd_params(dev, params, flags, mtu);
+ if (err == BPF_FIB_LKUP_RET_VLAN_FAILURE)
+ params->ifindex = in_ifindex;
+ return err;
}
#endif
#if IS_ENABLED(CONFIG_IPV6)
static int bpf_ipv6_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
- u32 flags, bool check_mtu)
+ u32 flags, bool check_mtu,
+ struct net_device **fwd_dev)
{
struct in6_addr *src = (struct in6_addr *) params->ipv6_src;
struct in6_addr *dst = (struct in6_addr *) params->ipv6_dst;
+ u32 in_ifindex = params->ifindex;
struct fib6_result res = {};
struct neighbour *neigh;
struct net_device *dev;
@@ -6486,13 +6513,19 @@ static int bpf_ipv6_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
memcpy(params->smac, dev->dev_addr, ETH_ALEN);
set_fwd_params:
- return bpf_fib_set_fwd_params(params, mtu);
+ if (fwd_dev)
+ *fwd_dev = dev;
+ err = bpf_fib_set_fwd_params(dev, params, flags, mtu);
+ if (err == BPF_FIB_LKUP_RET_VLAN_FAILURE)
+ params->ifindex = in_ifindex;
+ return err;
}
#endif
#define BPF_FIB_LOOKUP_MASK (BPF_FIB_LOOKUP_DIRECT | BPF_FIB_LOOKUP_OUTPUT | \
BPF_FIB_LOOKUP_SKIP_NEIGH | BPF_FIB_LOOKUP_TBID | \
- BPF_FIB_LOOKUP_SRC | BPF_FIB_LOOKUP_MARK)
+ BPF_FIB_LOOKUP_SRC | BPF_FIB_LOOKUP_MARK | \
+ BPF_FIB_LOOKUP_VLAN)
BPF_CALL_4(bpf_xdp_fib_lookup, struct xdp_buff *, ctx,
struct bpf_fib_lookup *, params, int, plen, u32, flags)
@@ -6507,12 +6540,12 @@ BPF_CALL_4(bpf_xdp_fib_lookup, struct xdp_buff *, ctx,
#if IS_ENABLED(CONFIG_INET)
case AF_INET:
return bpf_ipv4_fib_lookup(dev_net(ctx->rxq->dev), params,
- flags, true);
+ flags, true, NULL);
#endif
#if IS_ENABLED(CONFIG_IPV6)
case AF_INET6:
return bpf_ipv6_fib_lookup(dev_net(ctx->rxq->dev), params,
- flags, true);
+ flags, true, NULL);
#endif
}
return -EAFNOSUPPORT;
@@ -6532,6 +6565,7 @@ BPF_CALL_4(bpf_skb_fib_lookup, struct sk_buff *, skb,
struct bpf_fib_lookup *, params, int, plen, u32, flags)
{
struct net *net = dev_net(skb->dev);
+ struct net_device *fwd_dev = NULL;
int rc = -EAFNOSUPPORT;
bool check_mtu = false;
@@ -6547,29 +6581,26 @@ BPF_CALL_4(bpf_skb_fib_lookup, struct sk_buff *, skb,
switch (params->family) {
#if IS_ENABLED(CONFIG_INET)
case AF_INET:
- rc = bpf_ipv4_fib_lookup(net, params, flags, check_mtu);
+ rc = bpf_ipv4_fib_lookup(net, params, flags, check_mtu,
+ &fwd_dev);
break;
#endif
#if IS_ENABLED(CONFIG_IPV6)
case AF_INET6:
- rc = bpf_ipv6_fib_lookup(net, params, flags, check_mtu);
+ rc = bpf_ipv6_fib_lookup(net, params, flags, check_mtu,
+ &fwd_dev);
break;
#endif
}
if (rc == BPF_FIB_LKUP_RET_SUCCESS && !check_mtu) {
- struct net_device *dev;
-
- /* When tot_len isn't provided by user, check skb
- * against MTU of FIB lookup resulting net_device
+ /* without tot_len, check the skb against the FIB-result
+ * device's MTU
*/
- dev = dev_get_by_index_rcu(net, params->ifindex);
- if (unlikely(!dev))
- return -ENODEV;
- if (!is_skb_forwardable(dev, skb))
+ if (!is_skb_forwardable(fwd_dev, skb))
rc = BPF_FIB_LKUP_RET_FRAG_NEEDED;
- params->mtu_result = dev->mtu; /* union with tot_len */
+ params->mtu_result = fwd_dev->mtu; /* union with tot_len */
}
return rc;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 89b36de5fdbb..8d0058d88eb2 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -3532,6 +3532,26 @@ union bpf_attr {
* Use the mark present in *params*->mark for the fib lookup.
* This option should not be used with BPF_FIB_LOOKUP_DIRECT,
* as it only has meaning for full lookups.
+ * **BPF_FIB_LOOKUP_VLAN**
+ * If the fib lookup resolves to a VLAN device whose
+ * parent is a real (non-VLAN) device, set
+ * *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; if it
+ * is itself a VLAN device (QinQ) or in another namespace,
+ * the egress cannot be reduced to a physical device plus
+ * one tag and the lookup returns
+ * **BPF_FIB_LKUP_RET_VLAN_FAILURE** with *params*->ifindex
+ * left at the input. Re-issue without
+ * **BPF_FIB_LOOKUP_VLAN** to obtain the VLAN device's own
+ * ifindex. The swap and the vlan fields
+ * are written only on success; other output fields keep
+ * the helper's existing behaviour, so a frag-needed result
+ * still reports the route mtu in *params*->mtu_result.
*
* *ctx* is either **struct xdp_md** for XDP programs or
* **struct sk_buff** tc cls_act programs.
@@ -7327,6 +7347,7 @@ enum {
BPF_FIB_LOOKUP_TBID = (1U << 3),
BPF_FIB_LOOKUP_SRC = (1U << 4),
BPF_FIB_LOOKUP_MARK = (1U << 5),
+ BPF_FIB_LOOKUP_VLAN = (1U << 6),
};
enum {
@@ -7340,6 +7361,7 @@ enum {
BPF_FIB_LKUP_RET_NO_NEIGH, /* no neighbor entry for nh */
BPF_FIB_LKUP_RET_FRAG_NEEDED, /* fragmentation required to fwd */
BPF_FIB_LKUP_RET_NO_SRC_ADDR, /* failed to derive IP src addr */
+ BPF_FIB_LKUP_RET_VLAN_FAILURE, /* VLAN egress, parent unresolvable */
};
struct bpf_fib_lookup {
@@ -7393,7 +7415,11 @@ struct bpf_fib_lookup {
union {
struct {
- /* output */
+ /*
+ * output with BPF_FIB_LOOKUP_VLAN: set from the
+ * resolved egress VLAN device (see the flag); zeroed
+ * on other successful lookups.
+ */
__be16 h_vlan_proto;
__be16 h_vlan_TCI;
};
--
2.54.0
^ permalink raw reply related [flat|nested] 10+ messages in thread
* [PATCH bpf-next v4 2/3] bpf: Add BPF_FIB_LOOKUP_VLAN_INPUT flag to bpf_fib_lookup() helper
2026-06-23 2:51 [PATCH bpf-next v4 0/3] bpf: bidirectional VLAN support for bpf_fib_lookup() Avinash Duduskar
2026-06-23 2:51 ` [PATCH bpf-next v4 1/3] bpf: Add BPF_FIB_LOOKUP_VLAN flag to bpf_fib_lookup() helper Avinash Duduskar
@ 2026-06-23 2:51 ` Avinash Duduskar
2026-06-23 12:00 ` Toke Høiland-Jørgensen
2026-06-23 2:51 ` [PATCH bpf-next v4 3/3] selftests/bpf: Add bpf_fib_lookup() VLAN flag tests Avinash Duduskar
2 siblings, 1 reply; 10+ messages in thread
From: Avinash Duduskar @ 2026-06-23 2:51 UTC (permalink / raw)
To: ast, daniel, andrii
Cc: eddyz87, memxor, martin.lau, song, yonghong.song, jolsa, emil,
john.fastabend, sdf, davem, edumazet, kuba, pabeni, horms, shuah,
hawk, yatsenko, leon.hwang, kpsingh, a.s.protopopov, ameryhung,
rongtao, eyal.birger, bpf, netdev, linux-kernel, linux-kselftest,
toke, dsahern
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 the flag 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>
---
include/uapi/linux/bpf.h | 21 ++++++++++-
net/core/filter.c | 66 +++++++++++++++++++++++++++++++---
tools/include/uapi/linux/bpf.h | 21 ++++++++++-
3 files changed, 101 insertions(+), 7 deletions(-)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 8d0058d88eb2..46a1443534bd 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -3552,6 +3552,22 @@ union bpf_attr {
* are written only on success; other output fields keep
* the helper's existing behaviour, so a frag-needed result
* still reports the route mtu in *params*->mtu_result.
+ * **BPF_FIB_LOOKUP_VLAN_INPUT**
+ * Treat *params*->h_vlan_proto and *params*->h_vlan_TCI
+ * as an input VLAN tag and run the lookup as if ingress
+ * had happened on the VLAN subinterface carrying that tag
+ * on *params*->ifindex. The VID is the low 12 bits of
+ * *params*->h_vlan_TCI; *params*->h_vlan_proto must be
+ * ETH_P_8021Q or ETH_P_8021AD in network byte order, else
+ * **-EINVAL**. If *params*->ifindex is itself a VLAN
+ * device, its inner (QinQ) subinterface is matched; for a
+ * bond or team, pass the master's ifindex. An unmatched
+ * tag, a down device, or one in another namespace returns
+ * **BPF_FIB_LKUP_RET_NOT_FWDED**, mirroring real ingress.
+ * A VID of 0 is looked up literally, so do not set this
+ * flag for priority-tagged frames. Cannot be combined with
+ * **BPF_FIB_LOOKUP_TBID** or **BPF_FIB_LOOKUP_OUTPUT**
+ * (returns **-EINVAL**).
*
* *ctx* is either **struct xdp_md** for XDP programs or
* **struct sk_buff** tc cls_act programs.
@@ -7348,6 +7364,7 @@ enum {
BPF_FIB_LOOKUP_SRC = (1U << 4),
BPF_FIB_LOOKUP_MARK = (1U << 5),
BPF_FIB_LOOKUP_VLAN = (1U << 6),
+ BPF_FIB_LOOKUP_VLAN_INPUT = (1U << 7),
};
enum {
@@ -7418,7 +7435,9 @@ struct bpf_fib_lookup {
/*
* output with BPF_FIB_LOOKUP_VLAN: set from the
* resolved egress VLAN device (see the flag); zeroed
- * on other successful lookups.
+ * on other successful lookups. input with
+ * BPF_FIB_LOOKUP_VLAN_INPUT: the VLAN tag to scope
+ * the lookup by.
*/
__be16 h_vlan_proto;
__be16 h_vlan_TCI;
diff --git a/net/core/filter.c b/net/core/filter.c
index 8345295d84de..fc603cc36ce9 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -6228,6 +6228,25 @@ static int bpf_fib_set_fwd_params(struct net_device *dev,
return 0;
}
+
+static struct net_device *bpf_fib_vlan_input_dev(struct net_device *dev,
+ const struct bpf_fib_lookup *params)
+{
+ __be16 proto = params->h_vlan_proto;
+ struct net_device *vlan_dev;
+ u16 vid;
+
+ if (proto != htons(ETH_P_8021Q) && proto != htons(ETH_P_8021AD))
+ return ERR_PTR(-EINVAL);
+
+ vid = ntohs(params->h_vlan_TCI) & VLAN_VID_MASK;
+ vlan_dev = __vlan_find_dev_deep_rcu(dev, proto, vid);
+ if (!vlan_dev || !(vlan_dev->flags & IFF_UP) ||
+ !net_eq(dev_net(vlan_dev), dev_net(dev)))
+ return NULL;
+
+ return vlan_dev;
+}
#endif
#if IS_ENABLED(CONFIG_INET)
@@ -6249,6 +6268,14 @@ static int bpf_ipv4_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
if (unlikely(!dev))
return -ENODEV;
+ if (flags & BPF_FIB_LOOKUP_VLAN_INPUT) {
+ dev = bpf_fib_vlan_input_dev(dev, params);
+ if (IS_ERR(dev))
+ return PTR_ERR(dev);
+ if (!dev)
+ return BPF_FIB_LKUP_RET_NOT_FWDED;
+ }
+
/* verify forwarding is enabled on this interface */
in_dev = __in_dev_get_rcu(dev);
if (unlikely(!in_dev || !IN_DEV_FORWARD(in_dev)))
@@ -6258,7 +6285,11 @@ static int bpf_ipv4_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
fl4.flowi4_iif = 1;
fl4.flowi4_oif = params->ifindex;
} else {
- fl4.flowi4_iif = params->ifindex;
+ /*
+ * dev->ifindex, not params->ifindex: VLAN_INPUT may have
+ * resolved dev to a subinterface above.
+ */
+ fl4.flowi4_iif = dev->ifindex;
fl4.flowi4_oif = 0;
}
fl4.flowi4_dscp = inet_dsfield_to_dscp(params->tos);
@@ -6401,6 +6432,14 @@ static int bpf_ipv6_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
if (unlikely(!dev))
return -ENODEV;
+ if (flags & BPF_FIB_LOOKUP_VLAN_INPUT) {
+ dev = bpf_fib_vlan_input_dev(dev, params);
+ if (IS_ERR(dev))
+ return PTR_ERR(dev);
+ if (!dev)
+ return BPF_FIB_LKUP_RET_NOT_FWDED;
+ }
+
idev = __in6_dev_get_safely(dev);
if (unlikely(!idev || !READ_ONCE(idev->cnf.forwarding)))
return BPF_FIB_LKUP_RET_FWD_DISABLED;
@@ -6409,7 +6448,12 @@ static int bpf_ipv6_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
fl6.flowi6_iif = 1;
oif = fl6.flowi6_oif = params->ifindex;
} else {
- oif = fl6.flowi6_iif = params->ifindex;
+ /*
+ * dev->ifindex, not params->ifindex: VLAN_INPUT may have
+ * resolved dev to a subinterface above.
+ */
+ oif = dev->ifindex;
+ fl6.flowi6_iif = oif;
fl6.flowi6_oif = 0;
strict = RT6_LOOKUP_F_HAS_SADDR;
}
@@ -6525,7 +6569,19 @@ static int bpf_ipv6_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
#define BPF_FIB_LOOKUP_MASK (BPF_FIB_LOOKUP_DIRECT | BPF_FIB_LOOKUP_OUTPUT | \
BPF_FIB_LOOKUP_SKIP_NEIGH | BPF_FIB_LOOKUP_TBID | \
BPF_FIB_LOOKUP_SRC | BPF_FIB_LOOKUP_MARK | \
- BPF_FIB_LOOKUP_VLAN)
+ BPF_FIB_LOOKUP_VLAN | BPF_FIB_LOOKUP_VLAN_INPUT)
+
+static bool bpf_fib_lookup_flags_ok(u32 flags)
+{
+ if (flags & ~BPF_FIB_LOOKUP_MASK)
+ return false;
+
+ if ((flags & BPF_FIB_LOOKUP_VLAN_INPUT) &&
+ (flags & (BPF_FIB_LOOKUP_TBID | BPF_FIB_LOOKUP_OUTPUT)))
+ return false;
+
+ return true;
+}
BPF_CALL_4(bpf_xdp_fib_lookup, struct xdp_buff *, ctx,
struct bpf_fib_lookup *, params, int, plen, u32, flags)
@@ -6533,7 +6589,7 @@ BPF_CALL_4(bpf_xdp_fib_lookup, struct xdp_buff *, ctx,
if (plen < sizeof(*params))
return -EINVAL;
- if (flags & ~BPF_FIB_LOOKUP_MASK)
+ if (!bpf_fib_lookup_flags_ok(flags))
return -EINVAL;
switch (params->family) {
@@ -6572,7 +6628,7 @@ BPF_CALL_4(bpf_skb_fib_lookup, struct sk_buff *, skb,
if (plen < sizeof(*params))
return -EINVAL;
- if (flags & ~BPF_FIB_LOOKUP_MASK)
+ if (!bpf_fib_lookup_flags_ok(flags))
return -EINVAL;
if (params->tot_len)
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 8d0058d88eb2..46a1443534bd 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -3552,6 +3552,22 @@ union bpf_attr {
* are written only on success; other output fields keep
* the helper's existing behaviour, so a frag-needed result
* still reports the route mtu in *params*->mtu_result.
+ * **BPF_FIB_LOOKUP_VLAN_INPUT**
+ * Treat *params*->h_vlan_proto and *params*->h_vlan_TCI
+ * as an input VLAN tag and run the lookup as if ingress
+ * had happened on the VLAN subinterface carrying that tag
+ * on *params*->ifindex. The VID is the low 12 bits of
+ * *params*->h_vlan_TCI; *params*->h_vlan_proto must be
+ * ETH_P_8021Q or ETH_P_8021AD in network byte order, else
+ * **-EINVAL**. If *params*->ifindex is itself a VLAN
+ * device, its inner (QinQ) subinterface is matched; for a
+ * bond or team, pass the master's ifindex. An unmatched
+ * tag, a down device, or one in another namespace returns
+ * **BPF_FIB_LKUP_RET_NOT_FWDED**, mirroring real ingress.
+ * A VID of 0 is looked up literally, so do not set this
+ * flag for priority-tagged frames. Cannot be combined with
+ * **BPF_FIB_LOOKUP_TBID** or **BPF_FIB_LOOKUP_OUTPUT**
+ * (returns **-EINVAL**).
*
* *ctx* is either **struct xdp_md** for XDP programs or
* **struct sk_buff** tc cls_act programs.
@@ -7348,6 +7364,7 @@ enum {
BPF_FIB_LOOKUP_SRC = (1U << 4),
BPF_FIB_LOOKUP_MARK = (1U << 5),
BPF_FIB_LOOKUP_VLAN = (1U << 6),
+ BPF_FIB_LOOKUP_VLAN_INPUT = (1U << 7),
};
enum {
@@ -7418,7 +7435,9 @@ struct bpf_fib_lookup {
/*
* output with BPF_FIB_LOOKUP_VLAN: set from the
* resolved egress VLAN device (see the flag); zeroed
- * on other successful lookups.
+ * on other successful lookups. input with
+ * BPF_FIB_LOOKUP_VLAN_INPUT: the VLAN tag to scope
+ * the lookup by.
*/
__be16 h_vlan_proto;
__be16 h_vlan_TCI;
--
2.54.0
^ permalink raw reply related [flat|nested] 10+ messages in thread
* [PATCH bpf-next v4 3/3] selftests/bpf: Add bpf_fib_lookup() VLAN flag tests
2026-06-23 2:51 [PATCH bpf-next v4 0/3] bpf: bidirectional VLAN support for bpf_fib_lookup() Avinash Duduskar
2026-06-23 2:51 ` [PATCH bpf-next v4 1/3] bpf: Add BPF_FIB_LOOKUP_VLAN flag to bpf_fib_lookup() helper Avinash Duduskar
2026-06-23 2:51 ` [PATCH bpf-next v4 2/3] bpf: Add BPF_FIB_LOOKUP_VLAN_INPUT " Avinash Duduskar
@ 2026-06-23 2:51 ` Avinash Duduskar
2026-06-23 3:39 ` bot+bpf-ci
2026-06-23 12:36 ` kernel test robot
2 siblings, 2 replies; 10+ messages in thread
From: Avinash Duduskar @ 2026-06-23 2:51 UTC (permalink / raw)
To: ast, daniel, andrii
Cc: eddyz87, memxor, martin.lau, song, yonghong.song, jolsa, emil,
john.fastabend, sdf, davem, edumazet, kuba, pabeni, horms, shuah,
hawk, yatsenko, leon.hwang, kpsingh, a.s.protopopov, ameryhung,
rongtao, eyal.birger, bpf, netdev, linux-kernel, linux-kselftest,
toke, dsahern
Cover both directions of the new VLAN flags in the fib_lookup test,
38 table cases plus dedicated cross-netns and XDP-redirect subtests.
For BPF_FIB_LOOKUP_VLAN the egress cases assert: without the flag the
lookup returns the VLAN netdev's ifindex and zeroed vlan fields, with
the flag it returns the parent's ifindex plus the tag (including via
a neighbour resolved on the VLAN device, in OUTPUT mode, over a bond,
and through a DIRECT|TBID table), with the flag on a non-VLAN egress
it changes nothing, for a stacked VLAN (QinQ) it returns
BPF_FIB_LKUP_RET_VLAN_FAILURE with params->ifindex left at the input, a
lookup without the flag returns the inner VLAN device's ifindex, and
a frag-needed return reports the route mtu in mtu_result while leaving
the swap unwritten.
The VLAN_FAILURE arms are IPv4. bpf_ipv6_fib_lookup() restores
params->ifindex with the same save/restore the IPv4 arms exercise, so an
IPv6 VLAN_FAILURE arm would only re-test shared code.
For BPF_FIB_LOOKUP_VLAN_INPUT, an iif rule on the subinterface routes
the same destination to a different gateway, so the asserted gateway
shows which device the lookup used as ingress: without the flag the
main table answers, with a matching tag the subinterface's table
does, with or without SKIP_NEIGH, and BPF_FIB_LOOKUP_SRC selects the
subinterface's address. A VRF-enslaved subinterface selects the VRF
table through the l3mdev rule and, with DIRECT, through
l3mdev_fib_table_rcu(). One case sets BPF_FIB_LOOKUP_VLAN as well and
asserts both directions work in a single lookup. Resolution semantics
are pinned: an 802.1ad tag resolves its device, PCP and DEI bits in
h_vlan_TCI are ignored, a VLAN ifindex resolves the inner QinQ
device, a tag on a bond master resolves while the same tag on the
bond port does not.
The error cases assert -EINVAL for an invalid h_vlan_proto on both
address families, for the TBID and OUTPUT flag combinations and for
an unknown flag bit, and BPF_FIB_LKUP_RET_NOT_FWDED for a VID with no
configured device on both families, for a VID-0 priority tag and for
a device that exists but is down. The failure cases also assert that
params is left untouched. By contrast, a no-neighbour case whose
input and egress devices differ asserts NO_NEIGH reports the egress
ifindex, not the input: only VLAN_FAILURE rewinds params->ifindex to
the input.
A separate subtest moves a VLAN device into a second netns while it
stays registered on its parent, and checks both directions refuse to
cross the boundary: the input flag fails closed with the tag and
ifindex untouched, and the egress flag returns
BPF_FIB_LKUP_RET_VLAN_FAILURE without publishing the foreign parent's
ifindex.
The tbid read-back check is skipped for DIRECT cases that set
BPF_FIB_LOOKUP_VLAN, since a successful swap packs the vlan fields
into the union the check reads.
Re-run the cases through bpf_xdp_fib_lookup() as well: the egress flag
exists because VLAN devices have no XDP xmit, so XDP is the primary
consumer. bpf_prog_test_run uses the netns' loopback for the xdp context's
device, so the lookup runs against the test netns' FIB, and the
path-independent results (return code, swapped ifindex, vlan tag, gateway)
are asserted to match the skb path.
A live-frames subtest (test_fib_lookup_vlan_redirect) drives real
frames through the XDP redirect path with BPF_F_TEST_XDP_LIVE_FRAMES, the
native xdp_do_redirect() plus xdp_do_flush() path. A reducible VLAN
egress is redirected to the physical parent and delivered to its peer;
a QinQ egress returns VLAN_FAILURE and is passed to the stack, since
redirecting to the VLAN device would drop the frame at xdp_do_flush()
(no ndo_xdp_xmit). The redirect program distinguishes SUCCESS from not;
the table and netns arms pin the exact VLAN_FAILURE value.
Signed-off-by: Avinash Duduskar <avinash.duduskar@gmail.com>
---
.../selftests/bpf/prog_tests/fib_lookup.c | 696 +++++++++++++++++-
.../testing/selftests/bpf/progs/fib_lookup.c | 36 +
2 files changed, 728 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/fib_lookup.c b/tools/testing/selftests/bpf/prog_tests/fib_lookup.c
index bd7658958004..d51bc3332e56 100644
--- a/tools/testing/selftests/bpf/prog_tests/fib_lookup.c
+++ b/tools/testing/selftests/bpf/prog_tests/fib_lookup.c
@@ -2,6 +2,7 @@
/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
#include <linux/rtnetlink.h>
+#include <linux/if_ether.h>
#include <sys/types.h>
#include <net/if.h>
@@ -23,6 +24,7 @@
#define IPV4_TBID_ADDR "172.0.0.254"
#define IPV4_TBID_NET "172.0.0.0"
#define IPV4_TBID_DST "172.0.0.2"
+#define IPV4_TBID_NONEIGH_DST "172.0.0.5"
#define IPV6_TBID_ADDR "fd00::FFFF"
#define IPV6_TBID_NET "fd00::"
#define IPV6_TBID_DST "fd00::2"
@@ -37,6 +39,41 @@
#define IPV6_LOCAL "fd01::3"
#define IPV6_GW1 "fd01::1"
#define IPV6_GW2 "fd01::2"
+#define VLAN_ID 100
+#define VLAN_IFACE "veth1.100"
+#define VLAN_ID_DOWN 102
+#define VLAN_IFACE_DOWN "veth1.102"
+#define QINQ_OUTER_IFACE "veth1.200"
+#define QINQ_INNER_IFACE "veth1.200.300"
+#define VLAN_TABLE "300"
+#define IPV4_VLAN_IFACE_ADDR "10.5.0.254"
+#define IPV4_VLAN_EGRESS_DST "10.5.0.2"
+#define IPV4_QINQ_DST "10.7.0.2"
+#define IPV4_VLAN_DST "10.6.0.2"
+#define IPV4_VLAN_GW "10.5.0.1"
+#define IPV6_VLAN_IFACE_ADDR "fd02::254"
+#define IPV6_VLAN_EGRESS_DST "fd02::2"
+#define IPV6_VLAN_DST "fd03::2"
+#define IPV6_VLAN_GW "fd02::1"
+#define VLAN_VID_UNUSED 999
+#define VRF_IFACE "vrf-blue"
+#define VRF_TABLE "1000"
+#define VRF_VLAN_ID 101
+#define VRF_VLAN_IFACE "veth1.101"
+#define IPV4_VRF_IFACE_ADDR "10.8.0.254"
+#define IPV4_VRF_GW "10.8.0.1"
+#define IPV4_VRF_DST "10.9.0.2"
+#define TBID_VLAN_ID 50
+#define TBID_VLAN_IFACE "veth2.50"
+#define IPV4_TBID_VLAN_DST "172.2.0.2"
+#define IPV4_BOND_VLAN_DST "10.11.0.2"
+#define IPV4_VLAN_MTU_DST "10.5.9.2"
+#define QINQ_AD_VLAN_ID 200
+#define QINQ_INNER_VLAN_ID 300
+#define BOND_IFACE "bond99"
+#define BOND_PORT "veth3"
+#define BOND_PORT_PEER "veth4"
+#define BOND_VLAN_ID 500
#define DMAC "11:11:11:11:11:11"
#define DMAC_INIT { 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, }
#define DMAC2 "01:01:01:01:01:01"
@@ -52,6 +89,17 @@ struct fib_lookup_test {
__u32 tbid;
__u8 dmac[6];
__u32 mark;
+ /*
+ * input tag with BPF_FIB_LOOKUP_VLAN_INPUT; expected output tag
+ * with BPF_FIB_LOOKUP_VLAN (checked when check_vlan is set)
+ */
+ __u16 vlan_proto;
+ __u16 vlan_id;
+ bool check_vlan;
+ const char *expected_dev; /* expected params->ifindex after lookup */
+ const char *iif; /* override the default veth1 input device */
+ __u16 tot_len; /* triggers the in-lookup mtu check when set */
+ __u16 expected_mtu; /* expected mtu_result (union with tot_len) */
};
static const struct fib_lookup_test tests[] = {
@@ -79,6 +127,17 @@ static const struct fib_lookup_test tests[] = {
.daddr = IPV4_TBID_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
.lookup_flags = BPF_FIB_LOOKUP_DIRECT | BPF_FIB_LOOKUP_TBID, .tbid = 100,
.dmac = DMAC_INIT2, },
+ /*
+ * An error that returns after the egress device is resolved must
+ * report the egress ifindex, not the input. This routes from input
+ * veth1 via veth2 (table 100) to a dst with no neighbour, so
+ * input != egress, pinning NO_NEIGH to the egress device.
+ */
+ { .desc = "IPv4 NO_NEIGH reports the egress ifindex, not the input",
+ .daddr = IPV4_TBID_NONEIGH_DST,
+ .expected_ret = BPF_FIB_LKUP_RET_NO_NEIGH,
+ .lookup_flags = BPF_FIB_LOOKUP_DIRECT | BPF_FIB_LOOKUP_TBID, .tbid = 100,
+ .expected_dev = "veth2", },
{ .desc = "IPv6 TBID lookup failure",
.daddr = IPV6_TBID_DST, .expected_ret = BPF_FIB_LKUP_RET_NOT_FWDED,
.lookup_flags = BPF_FIB_LOOKUP_DIRECT | BPF_FIB_LOOKUP_TBID,
@@ -142,6 +201,223 @@ static const struct fib_lookup_test tests[] = {
.expected_dst = IPV6_GW1,
.lookup_flags = BPF_FIB_LOOKUP_SKIP_NEIGH,
.mark = MARK, },
+ /* vlan egress resolution */
+ /*
+ * Invariant the VLAN-egress arms jointly enforce: a
+ * BPF_FIB_LOOKUP_VLAN SUCCESS always carries a physical,
+ * xmit-capable ifindex -- no SUCCESS ever returns a VLAN-device
+ * ifindex. Reducible arms pin ifindex == the physical parent; the
+ * QinQ and foreign-netns arms pin VLAN_FAILURE with params->ifindex
+ * left at the input, so a regression to best-effort (SUCCESS + the
+ * VLAN ifindex) fails one.
+ */
+ { .desc = "IPv4 VLAN egress, no flag",
+ .daddr = IPV4_VLAN_EGRESS_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .lookup_flags = BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .expected_dev = VLAN_IFACE, .check_vlan = true, },
+ { .desc = "IPv4 VLAN egress, single VLAN",
+ .daddr = IPV4_VLAN_EGRESS_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .expected_dev = "veth1", .check_vlan = true,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = VLAN_ID, },
+ /*
+ * skb path without tot_len: mtu_result is the FIB result (VLAN)
+ * device's mtu (1400) with or without the swap, not the parent's (1500)
+ */
+ { .desc = "IPv4 VLAN egress, skb-path mtu is the VLAN device's without the flag",
+ .daddr = IPV4_VLAN_EGRESS_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .lookup_flags = BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .expected_dev = VLAN_IFACE, .check_vlan = true, .expected_mtu = 1400, },
+ { .desc = "IPv4 VLAN egress, skb-path mtu stays the VLAN device's after the swap",
+ .daddr = IPV4_VLAN_EGRESS_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .expected_dev = "veth1", .check_vlan = true,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = VLAN_ID, .expected_mtu = 1400, },
+ { .desc = "IPv4 VLAN egress, flag set but egress is not a VLAN",
+ .daddr = IPV4_NUD_FAILED_ADDR, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .expected_dev = "veth1", .check_vlan = true, },
+ { .desc = "IPv4 VLAN egress, QinQ not reducible (VLAN_FAILURE)",
+ .daddr = IPV4_QINQ_DST,
+ .expected_ret = BPF_FIB_LKUP_RET_VLAN_FAILURE,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .expected_dev = "veth1", .check_vlan = true, },
+ { .desc = "IPv4 QinQ egress without the flag (escape hatch)",
+ .daddr = IPV4_QINQ_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .lookup_flags = BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .expected_dev = QINQ_INNER_IFACE, },
+ { .desc = "IPv6 VLAN egress, single VLAN",
+ .daddr = IPV6_VLAN_EGRESS_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .expected_dev = "veth1", .check_vlan = true,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = VLAN_ID, },
+ { .desc = "IPv4 VLAN egress, neighbour on the VLAN device",
+ .daddr = IPV4_VLAN_EGRESS_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN,
+ .expected_dev = "veth1", .check_vlan = true,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = VLAN_ID, .dmac = DMAC_INIT, },
+ { .desc = "IPv4 VLAN egress in OUTPUT mode",
+ .daddr = IPV4_VLAN_EGRESS_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .iif = VLAN_IFACE,
+ .lookup_flags = BPF_FIB_LOOKUP_OUTPUT | BPF_FIB_LOOKUP_VLAN |
+ BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .expected_dev = "veth1", .check_vlan = true,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = VLAN_ID, },
+ { .desc = "IPv4 VLAN egress over a bond",
+ .daddr = IPV4_BOND_VLAN_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .expected_dev = BOND_IFACE, .check_vlan = true,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = BOND_VLAN_ID, },
+ { .desc = "IPv4 VLAN egress via TBID table",
+ .daddr = IPV4_TBID_VLAN_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .lookup_flags = BPF_FIB_LOOKUP_DIRECT | BPF_FIB_LOOKUP_TBID |
+ BPF_FIB_LOOKUP_VLAN | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .tbid = 100,
+ .expected_dev = "veth2", .check_vlan = true,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = TBID_VLAN_ID, },
+ { .desc = "IPv4 VLAN egress, success writes mtu_result with the swap",
+ .daddr = IPV4_VLAN_MTU_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .tot_len = 500, .expected_mtu = 1000,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .expected_dev = "veth1", .check_vlan = true,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = VLAN_ID, },
+ { .desc = "IPv4 VLAN egress, FRAG_NEEDED reports mtu, swap unwritten",
+ .daddr = IPV4_VLAN_MTU_DST, .expected_ret = BPF_FIB_LKUP_RET_FRAG_NEEDED,
+ .tot_len = 1400, .expected_mtu = 1000,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .expected_dev = "veth1", .check_vlan = true, },
+ /* vlan tag as lookup input */
+ { .desc = "IPv4 VLAN input, no flag",
+ .daddr = IPV4_VLAN_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .expected_dst = IPV4_GW1,
+ .lookup_flags = BPF_FIB_LOOKUP_SKIP_NEIGH, },
+ { .desc = "IPv4 VLAN input, tag selects subinterface route",
+ .daddr = IPV4_VLAN_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .expected_dst = IPV4_VLAN_GW, .expected_dev = VLAN_IFACE,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN_INPUT | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = VLAN_ID, },
+ { .desc = "IPv6 VLAN input, tag selects subinterface route",
+ .daddr = IPV6_VLAN_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .expected_dst = IPV6_VLAN_GW, .expected_dev = VLAN_IFACE,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN_INPUT | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = VLAN_ID, },
+ { .desc = "IPv4 VLAN input and egress combined",
+ .daddr = IPV4_VLAN_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .expected_dst = IPV4_VLAN_GW, .expected_dev = "veth1",
+ .check_vlan = true,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN_INPUT | BPF_FIB_LOOKUP_VLAN |
+ BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = VLAN_ID, },
+ { .desc = "IPv4 VLAN input, neighbour resolved on the route",
+ .daddr = IPV4_VLAN_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .expected_dst = IPV4_VLAN_GW, .expected_dev = VLAN_IFACE,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN_INPUT,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = VLAN_ID, .dmac = DMAC_INIT2, },
+ { .desc = "IPv4 VLAN input, source address from the subinterface",
+ .daddr = IPV4_VLAN_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .expected_src = IPV4_VLAN_IFACE_ADDR,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN_INPUT | BPF_FIB_LOOKUP_SRC |
+ BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = VLAN_ID, },
+ /*
+ * VRF: the resolved subinterface is enslaved, so the l3mdev rule
+ * (full lookup) and l3mdev_fib_table_rcu() (DIRECT) must select
+ * the VRF table from the resolved ingress
+ */
+ { .desc = "IPv4 VLAN input, VRF subinterface, no flag",
+ .daddr = IPV4_VRF_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .expected_dst = IPV4_GW1,
+ .lookup_flags = BPF_FIB_LOOKUP_SKIP_NEIGH, },
+ { .desc = "IPv4 VLAN input, tag selects VRF table",
+ .daddr = IPV4_VRF_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .expected_dst = IPV4_VRF_GW, .expected_dev = VRF_VLAN_IFACE,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN_INPUT | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = VRF_VLAN_ID, },
+ { .desc = "IPv4 VLAN input, DIRECT uses VRF table from resolved ingress",
+ .daddr = IPV4_VRF_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .expected_dst = IPV4_VRF_GW, .expected_dev = VRF_VLAN_IFACE,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN_INPUT | BPF_FIB_LOOKUP_DIRECT |
+ BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = VRF_VLAN_ID, },
+ /*
+ * failure arms also assert params is left untouched: ifindex still
+ * names the physical device and the input tag bytes survive
+ */
+ { .desc = "IPv4 VLAN input, invalid proto",
+ .daddr = IPV4_VLAN_DST, .expected_ret = -EINVAL,
+ .expected_dev = "veth1", .check_vlan = true,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN_INPUT | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .vlan_proto = 0x1234, .vlan_id = VLAN_ID, },
+ { .desc = "IPv4 VLAN input, unmatched VID",
+ .daddr = IPV4_VLAN_DST, .expected_ret = BPF_FIB_LKUP_RET_NOT_FWDED,
+ .expected_dev = "veth1", .check_vlan = true,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN_INPUT | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = VLAN_VID_UNUSED, },
+ { .desc = "IPv4 VLAN input, subinterface down",
+ .daddr = IPV4_VLAN_DST, .expected_ret = BPF_FIB_LKUP_RET_NOT_FWDED,
+ .expected_dev = "veth1", .check_vlan = true,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN_INPUT | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = VLAN_ID_DOWN, },
+ /*
+ * the resolver runs before the forwarding check, so on devices
+ * with forwarding off FWD_DISABLED (not NOT_FWDED) proves the tag
+ * resolved to that device and the lookup used it as ingress
+ */
+ { .desc = "IPv4 VLAN input, 802.1ad tag",
+ .daddr = IPV4_VLAN_DST, .expected_ret = BPF_FIB_LKUP_RET_FWD_DISABLED,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN_INPUT | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .vlan_proto = ETH_P_8021AD, .vlan_id = QINQ_AD_VLAN_ID, },
+ { .desc = "IPv4 VLAN input, PCP and DEI bits ignored in TCI",
+ .daddr = IPV4_VLAN_DST, .expected_ret = BPF_FIB_LKUP_RET_SUCCESS,
+ .expected_dst = IPV4_VLAN_GW,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN_INPUT | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = 0xe000 | VLAN_ID, },
+ { .desc = "IPv4 VLAN input, inner QinQ device from VLAN ifindex",
+ .daddr = IPV4_VLAN_DST, .expected_ret = BPF_FIB_LKUP_RET_FWD_DISABLED,
+ .iif = QINQ_OUTER_IFACE,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN_INPUT | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = QINQ_INNER_VLAN_ID, },
+ /*
+ * bonding: the VLANs live on the master, as on receive, where the
+ * frame is steered to the master before VLAN processing; a port
+ * ifindex does not match (ports carry vid state but no VLAN devs)
+ */
+ { .desc = "IPv4 VLAN input, tag on bond master resolves",
+ .daddr = IPV4_VLAN_DST, .expected_ret = BPF_FIB_LKUP_RET_FWD_DISABLED,
+ .iif = BOND_IFACE,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN_INPUT | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = BOND_VLAN_ID, },
+ { .desc = "IPv4 VLAN input, tag on bond port does not match",
+ .daddr = IPV4_VLAN_DST, .expected_ret = BPF_FIB_LKUP_RET_NOT_FWDED,
+ .iif = BOND_PORT, .expected_dev = BOND_PORT, .check_vlan = true,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN_INPUT | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = BOND_VLAN_ID, },
+ { .desc = "IPv6 VLAN input, invalid proto",
+ .daddr = IPV6_VLAN_DST, .expected_ret = -EINVAL,
+ .expected_dev = "veth1", .check_vlan = true,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN_INPUT | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .vlan_proto = 0x1234, .vlan_id = VLAN_ID, },
+ { .desc = "IPv4 VLAN input, VID 0 priority tag fails closed",
+ .daddr = IPV4_VLAN_DST, .expected_ret = BPF_FIB_LKUP_RET_NOT_FWDED,
+ .expected_dev = "veth1", .check_vlan = true,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN_INPUT | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = 0, },
+ { .desc = "IPv6 VLAN input, unmatched VID",
+ .daddr = IPV6_VLAN_DST, .expected_ret = BPF_FIB_LKUP_RET_NOT_FWDED,
+ .expected_dev = "veth1", .check_vlan = true,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN_INPUT | BPF_FIB_LOOKUP_SKIP_NEIGH,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = VLAN_VID_UNUSED, },
+ { .desc = "unknown flag bit rejected",
+ .daddr = IPV4_VLAN_DST, .expected_ret = -EINVAL,
+ .lookup_flags = (1 << 14) | BPF_FIB_LOOKUP_SKIP_NEIGH, },
+ { .desc = "IPv4 VLAN input rejected with TBID",
+ .daddr = IPV4_VLAN_DST, .expected_ret = -EINVAL,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN_INPUT | BPF_FIB_LOOKUP_TBID,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = VLAN_ID, },
+ { .desc = "IPv4 VLAN input rejected with OUTPUT",
+ .daddr = IPV4_VLAN_DST, .expected_ret = -EINVAL,
+ .lookup_flags = BPF_FIB_LOOKUP_VLAN_INPUT | BPF_FIB_LOOKUP_OUTPUT,
+ .vlan_proto = ETH_P_8021Q, .vlan_id = VLAN_ID, },
};
static int setup_netns(void)
@@ -204,6 +480,110 @@ static int setup_netns(void)
SYS(fail, "ip rule add prio 2 fwmark %d lookup %s", MARK, MARK_TABLE);
SYS(fail, "ip -6 rule add prio 2 fwmark %d lookup %s", MARK, MARK_TABLE);
+ /*
+ * Setup for vlan tests: a subinterface for egress resolution and
+ * tag-as-input, a QinQ stack, and an iif rule so the input tests
+ * observe which device the lookup used as ingress.
+ */
+ SYS(fail, "ip link add link veth1 name %s type vlan id %d",
+ VLAN_IFACE, VLAN_ID);
+ SYS(fail, "ip link set dev %s up", VLAN_IFACE);
+ /*
+ * lower than the veth1 parent (1500): the skb-path mtu check uses the
+ * FIB result (VLAN) device, so mtu_result is this value with or
+ * without the egress swap, which two arms below pin
+ */
+ SYS(fail, "ip link set dev %s mtu 1400", VLAN_IFACE);
+ SYS(fail, "ip addr add %s/24 dev %s", IPV4_VLAN_IFACE_ADDR, VLAN_IFACE);
+ SYS(fail, "ip addr add %s/64 dev %s nodad", IPV6_VLAN_IFACE_ADDR, VLAN_IFACE);
+
+ /*
+ * stays down: the input flag must treat its tag the way real
+ * ingress treats a frame arriving on a down VLAN device (drop)
+ */
+ SYS(fail, "ip link add link veth1 name %s type vlan id %d",
+ VLAN_IFACE_DOWN, VLAN_ID_DOWN);
+
+ err = write_sysctl("/proc/sys/net/ipv4/conf/" VLAN_IFACE "/forwarding", "1");
+ if (!ASSERT_OK(err, "write_sysctl(net.ipv4.conf." VLAN_IFACE ".forwarding)"))
+ goto fail;
+
+ err = write_sysctl("/proc/sys/net/ipv6/conf/" VLAN_IFACE "/forwarding", "1");
+ if (!ASSERT_OK(err, "write_sysctl(net.ipv6.conf." VLAN_IFACE ".forwarding)"))
+ goto fail;
+
+ SYS(fail, "ip link add link veth1 name %s type vlan proto 802.1ad id 200",
+ QINQ_OUTER_IFACE);
+ SYS(fail, "ip link add link %s name %s type vlan id 300",
+ QINQ_OUTER_IFACE, QINQ_INNER_IFACE);
+ SYS(fail, "ip link set dev %s up", QINQ_OUTER_IFACE);
+ SYS(fail, "ip link set dev %s up", QINQ_INNER_IFACE);
+ SYS(fail, "ip route add %s/32 dev %s", IPV4_QINQ_DST, QINQ_INNER_IFACE);
+
+ SYS(fail, "ip route add %s/32 via %s", IPV4_VLAN_DST, IPV4_GW1);
+ SYS(fail, "ip route add table %s %s/32 via %s",
+ VLAN_TABLE, IPV4_VLAN_DST, IPV4_VLAN_GW);
+ SYS(fail, "ip rule add prio 3 iif %s lookup %s", VLAN_IFACE, VLAN_TABLE);
+ SYS(fail, "ip -6 route add %s/128 via %s", IPV6_VLAN_DST, IPV6_GW1);
+ SYS(fail, "ip -6 route add table %s %s/128 via %s",
+ VLAN_TABLE, IPV6_VLAN_DST, IPV6_VLAN_GW);
+ SYS(fail, "ip -6 rule add prio 3 iif %s lookup %s", VLAN_IFACE, VLAN_TABLE);
+
+ /*
+ * a bond with one port and a VLAN on the bond: VLANs on a bond
+ * live on the master, so resolution succeeds for the master's
+ * ifindex and fails closed for a port's, matching receive, which
+ * steers the frame to the master before VLAN processing
+ */
+ SYS(fail, "ip link add %s type bond", BOND_IFACE);
+ SYS(fail, "ip link add %s type veth peer name %s", BOND_PORT, BOND_PORT_PEER);
+ SYS(fail, "ip link set %s master %s", BOND_PORT, BOND_IFACE);
+ SYS(fail, "ip link set dev %s up", BOND_IFACE);
+ SYS(fail, "ip link set dev %s up", BOND_PORT);
+ SYS(fail, "ip link add link %s name %s.%d type vlan id %d",
+ BOND_IFACE, BOND_IFACE, BOND_VLAN_ID, BOND_VLAN_ID);
+ SYS(fail, "ip link set dev %s.%d up", BOND_IFACE, BOND_VLAN_ID);
+ SYS(fail, "ip route add %s/32 dev %s.%d",
+ IPV4_BOND_VLAN_DST, BOND_IFACE, BOND_VLAN_ID);
+
+ /*
+ * a VRF with its own dedicated subinterface (the iif rules above
+ * must not see it), for the table-selection-by-ingress cases
+ */
+ SYS(fail, "ip link add %s type vrf table %s", VRF_IFACE, VRF_TABLE);
+ SYS(fail, "ip link set dev %s up", VRF_IFACE);
+ SYS(fail, "ip link add link veth1 name %s type vlan id %d",
+ VRF_VLAN_IFACE, VRF_VLAN_ID);
+ SYS(fail, "ip link set %s master %s", VRF_VLAN_IFACE, VRF_IFACE);
+ SYS(fail, "ip link set dev %s up", VRF_VLAN_IFACE);
+ SYS(fail, "ip addr add %s/24 dev %s", IPV4_VRF_IFACE_ADDR, VRF_VLAN_IFACE);
+ err = write_sysctl("/proc/sys/net/ipv4/conf/" VRF_VLAN_IFACE "/forwarding", "1");
+ if (!ASSERT_OK(err, "write_sysctl(net.ipv4.conf." VRF_VLAN_IFACE ".forwarding)"))
+ goto fail;
+ SYS(fail, "ip route add %s/32 via %s", IPV4_VRF_DST, IPV4_GW1);
+ SYS(fail, "ip route add table %s %s/32 via %s",
+ VRF_TABLE, IPV4_VRF_DST, IPV4_VRF_GW);
+
+ /* neighbours on the VLAN subinterface for the non-SKIP_NEIGH cases */
+ err = write_sysctl("/proc/sys/net/ipv4/neigh/" VLAN_IFACE "/gc_stale_time", "900");
+ if (!ASSERT_OK(err, "write_sysctl(net.ipv4.neigh." VLAN_IFACE ".gc_stale_time)"))
+ goto fail;
+ SYS(fail, "ip neigh add %s dev %s lladdr %s nud stale",
+ IPV4_VLAN_EGRESS_DST, VLAN_IFACE, DMAC);
+ SYS(fail, "ip neigh add %s dev %s lladdr %s nud stale",
+ IPV4_VLAN_GW, VLAN_IFACE, DMAC2);
+
+ /* a VLAN on veth2 with a route in the tbid test table */
+ SYS(fail, "ip link add link veth2 name %s type vlan id %d",
+ TBID_VLAN_IFACE, TBID_VLAN_ID);
+ SYS(fail, "ip link set dev %s up", TBID_VLAN_IFACE);
+ SYS(fail, "ip route add table 100 %s/32 dev %s",
+ IPV4_TBID_VLAN_DST, TBID_VLAN_IFACE);
+
+ /* a locked-mtu route via the subinterface for the FRAG_NEEDED case */
+ SYS(fail, "ip route add %s/32 dev %s mtu lock 1000",
+ IPV4_VLAN_MTU_DST, VLAN_IFACE);
+
return 0;
fail:
return -1;
@@ -218,9 +598,16 @@ static int set_lookup_params(struct bpf_fib_lookup *params,
memset(params, 0, sizeof(*params));
params->l4_protocol = IPPROTO_TCP;
- params->ifindex = ifindex;
+ params->ifindex = test->iif ? if_nametoindex(test->iif) : ifindex;
params->tbid = test->tbid;
params->mark = test->mark;
+ params->tot_len = test->tot_len;
+
+ /* h_vlan_proto/h_vlan_TCI union with tbid */
+ if (test->lookup_flags & BPF_FIB_LOOKUP_VLAN_INPUT) {
+ params->h_vlan_proto = htons(test->vlan_proto);
+ params->h_vlan_TCI = htons(test->vlan_id);
+ }
if (inet_pton(AF_INET6, test->daddr, params->ipv6_dst) == 1) {
params->family = AF_INET6;
@@ -298,7 +685,7 @@ void test_fib_lookup(void)
struct nstoken *nstoken = NULL;
struct __sk_buff skb = { };
struct fib_lookup *skel;
- int prog_fd, err, ret, i;
+ int prog_fd, xdp_fd, err, ret, i;
/* The test does not use the skb->data, so
* use pkt_v6 for both v6 and v4 test.
@@ -309,11 +696,16 @@ void test_fib_lookup(void)
.ctx_in = &skb,
.ctx_size_in = sizeof(skb),
);
+ LIBBPF_OPTS(bpf_test_run_opts, xdp_opts,
+ .data_in = &pkt_v6,
+ .data_size_in = sizeof(pkt_v6),
+ );
skel = fib_lookup__open_and_load();
if (!ASSERT_OK_PTR(skel, "skel open_and_load"))
return;
prog_fd = bpf_program__fd(skel->progs.fib_lookup);
+ xdp_fd = bpf_program__fd(skel->progs.fib_lookup_xdp);
SYS(fail, "ip netns add %s", NS_TEST);
@@ -352,6 +744,21 @@ void test_fib_lookup(void)
if (tests[i].expected_dst)
assert_dst_ip(fib_params, tests[i].expected_dst);
+ if (tests[i].expected_dev)
+ ASSERT_EQ(fib_params->ifindex,
+ if_nametoindex(tests[i].expected_dev), "ifindex");
+
+ if (tests[i].expected_mtu)
+ ASSERT_EQ(fib_params->mtu_result, tests[i].expected_mtu,
+ "mtu_result");
+
+ if (tests[i].check_vlan) {
+ ASSERT_EQ(fib_params->h_vlan_proto,
+ htons(tests[i].vlan_proto), "h_vlan_proto");
+ ASSERT_EQ(fib_params->h_vlan_TCI,
+ htons(tests[i].vlan_id), "h_vlan_TCI");
+ }
+
ret = memcmp(tests[i].dmac, fib_params->dmac, sizeof(tests[i].dmac));
if (!ASSERT_EQ(ret, 0, "dmac not match")) {
char expected[18], actual[18];
@@ -361,15 +768,296 @@ void test_fib_lookup(void)
printf("dmac expected %s actual %s ", expected, actual);
}
- // ensure tbid is zero'd out after fib lookup.
- if (tests[i].lookup_flags & BPF_FIB_LOOKUP_DIRECT) {
+ /*
+ * ensure tbid is zero'd out after fib lookup. With
+ * BPF_FIB_LOOKUP_VLAN the union holds the packed vlan
+ * fields instead, so skip the check for those.
+ */
+ if ((tests[i].lookup_flags & BPF_FIB_LOOKUP_DIRECT) &&
+ !(tests[i].lookup_flags & BPF_FIB_LOOKUP_VLAN)) {
if (!ASSERT_EQ(skel->bss->fib_params.tbid, 0,
"expected fib_params.tbid to be zero"))
goto fail;
}
}
+ /*
+ * Re-run the cases through bpf_xdp_fib_lookup(). test_run uses the
+ * current netns' loopback for ctx->rxq->dev, so dev_net() is NS_TEST
+ * and the lookup runs against its FIB. The path-independent results
+ * (return code, swapped ifindex, vlan tag, gateway) must match the skb
+ * path; the no-tot_len mtu_result is skb-specific and not rechecked.
+ */
+ for (i = 0; i < ARRAY_SIZE(tests); i++) {
+ if (set_lookup_params(fib_params, &tests[i], skb.ifindex))
+ continue;
+
+ skel->bss->fib_lookup_ret = -1;
+ skel->bss->lookup_flags = tests[i].lookup_flags;
+
+ err = bpf_prog_test_run_opts(xdp_fd, &xdp_opts);
+ if (!ASSERT_OK(err, "xdp test_run"))
+ continue;
+
+ if (!ASSERT_EQ(skel->bss->fib_lookup_ret, tests[i].expected_ret,
+ "xdp fib_lookup_ret"))
+ printf("(xdp) %s\n", tests[i].desc);
+
+ if (tests[i].expected_dev)
+ ASSERT_EQ(fib_params->ifindex,
+ if_nametoindex(tests[i].expected_dev),
+ "xdp ifindex");
+
+ if (tests[i].expected_dst)
+ assert_dst_ip(fib_params, tests[i].expected_dst);
+
+ if (tests[i].check_vlan) {
+ ASSERT_EQ(fib_params->h_vlan_proto,
+ htons(tests[i].vlan_proto), "xdp h_vlan_proto");
+ ASSERT_EQ(fib_params->h_vlan_TCI,
+ htons(tests[i].vlan_id), "xdp h_vlan_TCI");
+ }
+ }
+
+fail:
+ if (nstoken)
+ close_netns(nstoken);
+ SYS_NOFAIL("ip netns del " NS_TEST);
+ fib_lookup__destroy(skel);
+}
+
+#define NS_VLAN_A "fib_lookup_vlan_ns_a"
+#define NS_VLAN_B "fib_lookup_vlan_ns_b"
+
+/*
+ * A VLAN device can be moved to another netns while staying registered
+ * on its parent. Neither direction may then cross the boundary: the
+ * egress flag must not publish the foreign parent's ifindex, and the
+ * input flag must fail closed rather than use a foreign ingress.
+ */
+void test_fib_lookup_vlan_netns(void)
+{
+ struct bpf_fib_lookup *fib_params;
+ struct nstoken *nstoken = NULL;
+ struct __sk_buff skb = { };
+ struct fib_lookup *skel = NULL;
+ int prog_fd, err, parent_idx, vlan_idx;
+
+ LIBBPF_OPTS(bpf_test_run_opts, run_opts,
+ .data_in = &pkt_v6,
+ .data_size_in = sizeof(pkt_v6),
+ .ctx_in = &skb,
+ .ctx_size_in = sizeof(skb),
+ );
+
+ skel = fib_lookup__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "skel open_and_load"))
+ return;
+ prog_fd = bpf_program__fd(skel->progs.fib_lookup);
+ fib_params = &skel->bss->fib_params;
+
+ SYS(fail, "ip netns add %s", NS_VLAN_A);
+ SYS(fail, "ip netns add %s", NS_VLAN_B);
+
+ nstoken = open_netns(NS_VLAN_A);
+ if (!ASSERT_OK_PTR(nstoken, "open_netns(a)"))
+ goto fail;
+
+ SYS(fail, "ip link add veth7 type veth peer name veth8");
+ SYS(fail, "ip link set dev veth7 up");
+ SYS(fail, "ip link add link veth7 name veth7.66 type vlan id 66");
+ SYS(fail, "ip link set veth7.66 netns %s", NS_VLAN_B);
+
+ parent_idx = if_nametoindex("veth7");
+ if (!ASSERT_NEQ(parent_idx, 0, "if_nametoindex(veth7)"))
+ goto fail;
+
+ /*
+ * input: the moved device is still in veth7's VLAN group, but it
+ * lives in another netns, so the lookup must fail closed
+ */
+ skb.ifindex = parent_idx;
+ memset(fib_params, 0, sizeof(*fib_params));
+ fib_params->family = AF_INET;
+ fib_params->l4_protocol = IPPROTO_TCP;
+ fib_params->ifindex = parent_idx;
+ fib_params->h_vlan_proto = htons(ETH_P_8021Q);
+ fib_params->h_vlan_TCI = htons(66);
+ if (!ASSERT_EQ(inet_pton(AF_INET, "10.66.0.2", &fib_params->ipv4_dst),
+ 1, "inet_pton(dst)"))
+ goto fail;
+
+ skel->bss->fib_lookup_ret = -1;
+ skel->bss->lookup_flags = BPF_FIB_LOOKUP_VLAN_INPUT |
+ BPF_FIB_LOOKUP_SKIP_NEIGH;
+ err = bpf_prog_test_run_opts(prog_fd, &run_opts);
+ if (!ASSERT_OK(err, "test_run(input)"))
+ goto fail;
+ ASSERT_EQ(skel->bss->fib_lookup_ret, BPF_FIB_LKUP_RET_NOT_FWDED,
+ "input across netns fails closed");
+ ASSERT_EQ(fib_params->ifindex, parent_idx, "ifindex untouched");
+ ASSERT_EQ(fib_params->h_vlan_TCI, htons(66), "tag untouched");
+
+ close_netns(nstoken);
+ nstoken = open_netns(NS_VLAN_B);
+ if (!ASSERT_OK_PTR(nstoken, "open_netns(b)"))
+ goto fail;
+
+ /*
+ * egress: the fib result is the VLAN device here, but its parent
+ * is in the other netns, so the swap must not happen
+ */
+ SYS(fail, "ip link set dev veth7.66 up");
+ SYS(fail, "ip addr add 10.66.0.1/24 dev veth7.66");
+ err = write_sysctl("/proc/sys/net/ipv4/conf/veth7.66/forwarding", "1");
+ if (!ASSERT_OK(err, "write_sysctl(forwarding)"))
+ goto fail;
+
+ vlan_idx = if_nametoindex("veth7.66");
+ if (!ASSERT_NEQ(vlan_idx, 0, "if_nametoindex(veth7.66)"))
+ goto fail;
+
+ skb.ifindex = vlan_idx;
+ memset(fib_params, 0, sizeof(*fib_params));
+ fib_params->family = AF_INET;
+ fib_params->l4_protocol = IPPROTO_TCP;
+ fib_params->ifindex = vlan_idx;
+ if (!ASSERT_EQ(inet_pton(AF_INET, "10.66.0.2", &fib_params->ipv4_dst),
+ 1, "inet_pton(dst)") ||
+ !ASSERT_EQ(inet_pton(AF_INET, "10.66.0.1", &fib_params->ipv4_src),
+ 1, "inet_pton(src)"))
+ goto fail;
+
+ skel->bss->fib_lookup_ret = -1;
+ skel->bss->lookup_flags = BPF_FIB_LOOKUP_VLAN |
+ BPF_FIB_LOOKUP_SKIP_NEIGH;
+ err = bpf_prog_test_run_opts(prog_fd, &run_opts);
+ if (!ASSERT_OK(err, "test_run(egress)"))
+ goto fail;
+ ASSERT_EQ(skel->bss->fib_lookup_ret, BPF_FIB_LKUP_RET_VLAN_FAILURE,
+ "egress returns VLAN_FAILURE");
+ ASSERT_EQ(fib_params->ifindex, vlan_idx,
+ "foreign parent not published");
+ ASSERT_EQ(fib_params->h_vlan_TCI, 0, "vlan fields zero");
+
+fail:
+ if (nstoken)
+ close_netns(nstoken);
+ SYS_NOFAIL("ip netns del " NS_VLAN_A);
+ SYS_NOFAIL("ip netns del " NS_VLAN_B);
+ fib_lookup__destroy(skel);
+}
+
+#define REDIRECT_NPKTS 1000
+
+/*
+ * The egress flag exists so an XDP program can redirect to the physical
+ * parent. A redirect that lands on a VLAN device is dropped at
+ * xdp_do_flush(), because a VLAN device has no ndo_xdp_xmit. Drive real
+ * frames with BPF_F_TEST_XDP_LIVE_FRAMES, which runs the native
+ * xdp_do_redirect() + xdp_do_flush() path: a reducible VLAN egress
+ * resolves to veth1 and is delivered to its peer veth2, while a QinQ
+ * egress returns VLAN_FAILURE and is passed to the stack instead of
+ * redirected to a device that would silently drop it.
+ */
+void test_fib_lookup_vlan_redirect(void)
+{
+ int redirect_fd, err, veth1_idx, veth2_idx = -1;
+ struct bpf_fib_lookup *fib_params;
+ struct nstoken *nstoken = NULL;
+ struct fib_lookup *skel = NULL;
+ bool xdp_attached = false;
+
+ LIBBPF_OPTS(bpf_test_run_opts, lf_opts,
+ .data_in = &pkt_v4,
+ .data_size_in = sizeof(pkt_v4),
+ .flags = BPF_F_TEST_XDP_LIVE_FRAMES,
+ .repeat = REDIRECT_NPKTS,
+ );
+
+ skel = fib_lookup__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "skel open_and_load"))
+ return;
+ redirect_fd = bpf_program__fd(skel->progs.fib_lookup_redirect);
+ fib_params = &skel->bss->fib_params;
+
+ SYS(fail, "ip netns add %s", NS_TEST);
+ nstoken = open_netns(NS_TEST);
+ if (!ASSERT_OK_PTR(nstoken, "open_netns"))
+ goto fail;
+ if (setup_netns())
+ goto fail;
+
+ veth1_idx = if_nametoindex("veth1");
+ veth2_idx = if_nametoindex("veth2");
+ if (!ASSERT_NEQ(veth1_idx, 0, "if_nametoindex(veth1)") ||
+ !ASSERT_NEQ(veth2_idx, 0, "if_nametoindex(veth2)"))
+ goto fail;
+
+ /*
+ * A redirect to veth1 is delivered to its peer veth2. veth_xdp_xmit()
+ * only accepts the frame if veth2's NAPI is up, which on veth means
+ * veth2 carries an XDP program; xdp_count tallies what arrives.
+ */
+ err = bpf_xdp_attach(veth2_idx, bpf_program__fd(skel->progs.xdp_count),
+ XDP_FLAGS_DRV_MODE, NULL);
+ if (!ASSERT_OK(err, "attach xdp_count on veth2"))
+ goto fail;
+ xdp_attached = true;
+
+ /* reducible VLAN egress: resolves to the physical parent veth1 */
+ memset(fib_params, 0, sizeof(*fib_params));
+ fib_params->family = AF_INET;
+ fib_params->l4_protocol = IPPROTO_TCP;
+ fib_params->ifindex = veth1_idx;
+ if (!ASSERT_EQ(inet_pton(AF_INET, IPV4_IFACE_ADDR, &fib_params->ipv4_src),
+ 1, "inet_pton(src)") ||
+ !ASSERT_EQ(inet_pton(AF_INET, IPV4_VLAN_EGRESS_DST, &fib_params->ipv4_dst),
+ 1, "inet_pton(reducible dst)"))
+ goto fail;
+ skel->bss->lookup_flags = BPF_FIB_LOOKUP_VLAN | BPF_FIB_LOOKUP_SKIP_NEIGH;
+ skel->bss->redirected = 0;
+ skel->bss->passed = 0;
+ skel->bss->delivered = 0;
+
+ err = bpf_prog_test_run_opts(redirect_fd, &lf_opts);
+ if (!ASSERT_OK(err, "test_run(reducible egress)"))
+ goto fail;
+ ASSERT_EQ(skel->bss->redirected, REDIRECT_NPKTS, "reducible egress redirected");
+ ASSERT_EQ(skel->bss->passed, 0, "reducible egress not passed");
+ ASSERT_GT(skel->bss->delivered, 0, "reducible egress delivered to veth2");
+
+ /*
+ * QinQ egress: not reducible, so the lookup returns VLAN_FAILURE and
+ * the program passes the frame instead of redirecting to the inner
+ * VLAN device. redirected == 0 is the assertion that matters: the
+ * program did not redirect to a device that would drop the frame at
+ * xdp_do_flush(). veth2's delivered count is not checked here, since
+ * a passed frame can still reach veth2 through the stack's forwarding
+ * path, which is unrelated to the redirect under test.
+ */
+ memset(fib_params, 0, sizeof(*fib_params));
+ fib_params->family = AF_INET;
+ fib_params->l4_protocol = IPPROTO_TCP;
+ fib_params->ifindex = veth1_idx;
+ if (!ASSERT_EQ(inet_pton(AF_INET, IPV4_IFACE_ADDR, &fib_params->ipv4_src),
+ 1, "inet_pton(src)") ||
+ !ASSERT_EQ(inet_pton(AF_INET, IPV4_QINQ_DST, &fib_params->ipv4_dst),
+ 1, "inet_pton(qinq dst)"))
+ goto fail;
+ skel->bss->lookup_flags = BPF_FIB_LOOKUP_VLAN | BPF_FIB_LOOKUP_SKIP_NEIGH;
+ skel->bss->redirected = 0;
+ skel->bss->passed = 0;
+
+ err = bpf_prog_test_run_opts(redirect_fd, &lf_opts);
+ if (!ASSERT_OK(err, "test_run(qinq egress)"))
+ goto fail;
+ ASSERT_EQ(skel->bss->passed, REDIRECT_NPKTS, "qinq egress passed");
+ ASSERT_EQ(skel->bss->redirected, 0, "qinq egress not redirected");
+
fail:
+ if (xdp_attached)
+ bpf_xdp_detach(veth2_idx, XDP_FLAGS_DRV_MODE, NULL);
if (nstoken)
close_netns(nstoken);
SYS_NOFAIL("ip netns del " NS_TEST);
diff --git a/tools/testing/selftests/bpf/progs/fib_lookup.c b/tools/testing/selftests/bpf/progs/fib_lookup.c
index 7b5dd2214ff4..862a1e9457b4 100644
--- a/tools/testing/selftests/bpf/progs/fib_lookup.c
+++ b/tools/testing/selftests/bpf/progs/fib_lookup.c
@@ -19,4 +19,40 @@ int fib_lookup(struct __sk_buff *skb)
return TC_ACT_SHOT;
}
+SEC("xdp")
+int fib_lookup_xdp(struct xdp_md *ctx)
+{
+ fib_lookup_ret = bpf_fib_lookup(ctx, &fib_params, sizeof(fib_params),
+ lookup_flags);
+
+ return XDP_DROP;
+}
+
+int redirected = 0;
+int passed = 0;
+int delivered = 0;
+
+SEC("xdp")
+int fib_lookup_redirect(struct xdp_md *ctx)
+{
+ struct bpf_fib_lookup params = fib_params;
+ long ret;
+
+ ret = bpf_fib_lookup(ctx, ¶ms, sizeof(params), lookup_flags);
+ if (ret == BPF_FIB_LKUP_RET_SUCCESS) {
+ redirected++;
+ return bpf_redirect(params.ifindex, 0);
+ }
+
+ passed++;
+ return XDP_PASS;
+}
+
+SEC("xdp")
+int xdp_count(struct xdp_md *ctx)
+{
+ delivered++;
+ return XDP_DROP;
+}
+
char _license[] SEC("license") = "GPL";
--
2.54.0
^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH bpf-next v4 3/3] selftests/bpf: Add bpf_fib_lookup() VLAN flag tests
2026-06-23 2:51 ` [PATCH bpf-next v4 3/3] selftests/bpf: Add bpf_fib_lookup() VLAN flag tests Avinash Duduskar
@ 2026-06-23 3:39 ` bot+bpf-ci
2026-06-23 12:36 ` kernel test robot
1 sibling, 0 replies; 10+ messages in thread
From: bot+bpf-ci @ 2026-06-23 3:39 UTC (permalink / raw)
To: avinash.duduskar, ast, daniel, andrii
Cc: eddyz87, memxor, martin.lau, song, yonghong.song, jolsa, emil,
john.fastabend, sdf, davem, edumazet, kuba, pabeni, horms, shuah,
hawk, yatsenko, leon.hwang, kpsingh, a.s.protopopov, ameryhung,
rongtao, eyal.birger, bpf, netdev, linux-kernel, linux-kselftest,
toke, dsahern, ast, andrii, daniel, martin.lau, eddyz87,
yonghong.song, clm, ihor.solodrai
[-- Attachment #1: Type: text/plain, Size: 5118 bytes --]
> selftests/bpf: Add bpf_fib_lookup() VLAN flag tests
>
> Cover both directions of the new VLAN flags in the fib_lookup test,
> 38 table cases plus dedicated cross-netns and XDP-redirect subtests.
>
> For BPF_FIB_LOOKUP_VLAN the egress cases assert: without the flag the
> lookup returns the VLAN netdev's ifindex and zeroed vlan fields, with
> the flag it returns the parent's ifindex plus the tag (including via
> a neighbour resolved on the VLAN device, in OUTPUT mode, over a bond,
> and through a DIRECT|TBID table), with the flag on a non-VLAN egress
> it changes nothing, for a stacked VLAN (QinQ) it returns
> BPF_FIB_LKUP_RET_VLAN_FAILURE with params->ifindex left at the input, a
> lookup without the flag returns the inner VLAN device's ifindex, and
> a frag-needed return reports the route mtu in mtu_result while leaving
> the swap unwritten.
>
> The VLAN_FAILURE arms are IPv4. bpf_ipv6_fib_lookup() restores
> params->ifindex with the same save/restore the IPv4 arms exercise, so an
> IPv6 VLAN_FAILURE arm would only re-test shared code.
>
> For BPF_FIB_LOOKUP_VLAN_INPUT, an iif rule on the subinterface routes
> the same destination to a different gateway, so the asserted gateway
> shows which device the lookup used as ingress: without the flag the
> main table answers, with a matching tag the subinterface's table
> does, with or without SKIP_NEIGH, and BPF_FIB_LOOKUP_SRC selects the
> subinterface's address. A VRF-enslaved subinterface selects the VRF
> table through the l3mdev rule and, with DIRECT, through
> l3mdev_fib_table_rcu(). One case sets BPF_FIB_LOOKUP_VLAN as well and
> asserts both directions work in a single lookup. Resolution semantics
> are pinned: an 802.1ad tag resolves its device, PCP and DEI bits in
> h_vlan_TCI are ignored, a VLAN ifindex resolves the inner QinQ
> device, a tag on a bond master resolves while the same tag on the
> bond port does not.
>
> The error cases assert -EINVAL for an invalid h_vlan_proto on both
> address families, for the TBID and OUTPUT flag combinations and for
> an unknown flag bit, and BPF_FIB_LKUP_RET_NOT_FWDED for a VID with no
> configured device on both families, for a VID-0 priority tag and for
> a device that exists but is down. The failure cases also assert that
> params is left untouched. By contrast, a no-neighbour case whose
> input and egress devices differ asserts NO_NEIGH reports the egress
> ifindex, not the input: only VLAN_FAILURE rewinds params->ifindex to
> the input.
>
> A separate subtest moves a VLAN device into a second netns while it
> stays registered on its parent, and checks both directions refuse to
> cross the boundary: the input flag fails closed with the tag and
> ifindex untouched, and the egress flag returns
> BPF_FIB_LKUP_RET_VLAN_FAILURE without publishing the foreign parent's
> ifindex.
>
> The tbid read-back check is skipped for DIRECT cases that set
> BPF_FIB_LOOKUP_VLAN, since a successful swap packs the vlan fields
> into the union the check reads.
>
> Re-run the cases through bpf_xdp_fib_lookup() as well: the egress flag
> exists because VLAN devices have no XDP xmit, so XDP is the primary
> consumer. bpf_prog_test_run uses the netns' loopback for the xdp context's
> device, so the lookup runs against the test netns' FIB, and the
> path-independent results (return code, swapped ifindex, vlan tag, gateway)
> are asserted to match the skb path.
>
> A live-frames subtest (test_fib_lookup_vlan_redirect) drives real
> frames through the XDP redirect path with BPF_F_TEST_XDP_LIVE_FRAMES, the
> native xdp_do_redirect() plus xdp_do_flush() path. A reducible VLAN
> egress is redirected to the physical parent and delivered to its peer;
> a QinQ egress returns VLAN_FAILURE and is passed to the stack, since
> redirecting to the VLAN device would drop the frame at xdp_do_flush()
> (no ndo_xdp_xmit). The redirect program distinguishes SUCCESS from not;
> the table and netns arms pin the exact VLAN_FAILURE value.
This isn't a bug, but could the changelog be tightened?
The description runs roughly seven paragraphs that walk through what each
group of test arms asserts: the egress arms with and without the flag,
the input arms and VRF table selection, the error arms and their failure
modes, the netns subtest boundary checks, and the XDP redirect subtest
behaviour.
Much of it carries rationale, so this is a soft observation, but someone
wanting to understand the per-case behaviour can read it more quickly from
the test table itself. Could the summary focus on the why (the two new
flags and the invariants worth pinning) and lean on the test table for the
per-arm specifics?
---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
CI run summary: https://github.com/kernel-patches/bpf/actions/runs/27999579457
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH bpf-next v4 1/3] bpf: Add BPF_FIB_LOOKUP_VLAN flag to bpf_fib_lookup() helper
2026-06-23 2:51 ` [PATCH bpf-next v4 1/3] bpf: Add BPF_FIB_LOOKUP_VLAN flag to bpf_fib_lookup() helper Avinash Duduskar
@ 2026-06-23 11:58 ` Toke Høiland-Jørgensen
2026-06-23 18:28 ` Avinash Duduskar
0 siblings, 1 reply; 10+ messages in thread
From: Toke Høiland-Jørgensen @ 2026-06-23 11:58 UTC (permalink / raw)
To: Avinash Duduskar, ast, daniel, andrii
Cc: eddyz87, memxor, martin.lau, song, yonghong.song, jolsa, emil,
john.fastabend, sdf, davem, edumazet, kuba, pabeni, horms, shuah,
hawk, yatsenko, leon.hwang, kpsingh, a.s.protopopov, ameryhung,
rongtao, eyal.birger, bpf, netdev, linux-kernel, linux-kselftest,
dsahern
Avinash Duduskar <avinash.duduskar@gmail.com> writes:
> 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 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.
>
> On the skb path without tot_len the deferred mtu check is done against
> the resolved egress device. To keep that the VLAN device rather than
> the parent after the swap, bpf_ipv4_fib_lookup()/bpf_ipv6_fib_lookup()
> hand the FIB-result device back to the caller; the XDP path always
> runs the route-mtu check and passes NULL. 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>
> ---
> include/uapi/linux/bpf.h | 28 +++++++++++++-
> net/core/filter.c | 69 ++++++++++++++++++++++++----------
> tools/include/uapi/linux/bpf.h | 28 +++++++++++++-
> 3 files changed, 104 insertions(+), 21 deletions(-)
>
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 89b36de5fdbb..8d0058d88eb2 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -3532,6 +3532,26 @@ union bpf_attr {
> * Use the mark present in *params*->mark for the fib lookup.
> * This option should not be used with BPF_FIB_LOOKUP_DIRECT,
> * as it only has meaning for full lookups.
> + * **BPF_FIB_LOOKUP_VLAN**
> + * If the fib lookup resolves to a VLAN device whose
> + * parent is a real (non-VLAN) device, set
> + * *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; if it
> + * is itself a VLAN device (QinQ) or in another namespace,
> + * the egress cannot be reduced to a physical device plus
> + * one tag and the lookup returns
> + * **BPF_FIB_LKUP_RET_VLAN_FAILURE** with *params*->ifindex
> + * left at the input. Re-issue without
> + * **BPF_FIB_LOOKUP_VLAN** to obtain the VLAN device's own
> + * ifindex. The swap and the vlan fields
> + * are written only on success; other output fields keep
> + * the helper's existing behaviour, so a frag-needed result
> + * still reports the route mtu in *params*->mtu_result.
> *
> * *ctx* is either **struct xdp_md** for XDP programs or
> * **struct sk_buff** tc cls_act programs.
> @@ -7327,6 +7347,7 @@ enum {
> BPF_FIB_LOOKUP_TBID = (1U << 3),
> BPF_FIB_LOOKUP_SRC = (1U << 4),
> BPF_FIB_LOOKUP_MARK = (1U << 5),
> + BPF_FIB_LOOKUP_VLAN = (1U << 6),
> };
>
> enum {
> @@ -7340,6 +7361,7 @@ enum {
> BPF_FIB_LKUP_RET_NO_NEIGH, /* no neighbor entry for nh */
> BPF_FIB_LKUP_RET_FRAG_NEEDED, /* fragmentation required to fwd */
> BPF_FIB_LKUP_RET_NO_SRC_ADDR, /* failed to derive IP src addr */
> + BPF_FIB_LKUP_RET_VLAN_FAILURE, /* VLAN egress, parent unresolvable */
> };
>
> struct bpf_fib_lookup {
> @@ -7393,7 +7415,11 @@ struct bpf_fib_lookup {
>
> union {
> struct {
> - /* output */
> + /*
> + * output with BPF_FIB_LOOKUP_VLAN: set from the
> + * resolved egress VLAN device (see the flag); zeroed
> + * on other successful lookups.
> + */
> __be16 h_vlan_proto;
> __be16 h_vlan_TCI;
> };
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 2e96b4b847ce..8345295d84de 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -6201,10 +6201,28 @@ static const struct bpf_func_proto bpf_skb_get_xfrm_state_proto = {
> #endif
>
> #if IS_ENABLED(CONFIG_INET) || IS_ENABLED(CONFIG_IPV6)
> -static int bpf_fib_set_fwd_params(struct bpf_fib_lookup *params, u32 mtu)
> +static int bpf_fib_set_fwd_params(struct net_device *dev,
> + struct bpf_fib_lookup *params,
> + u32 flags, u32 mtu)
> {
> params->h_vlan_TCI = 0;
> params->h_vlan_proto = 0;
> +
> +#if IS_ENABLED(CONFIG_VLAN_8021Q)
> + if ((flags & BPF_FIB_LOOKUP_VLAN) && is_vlan_dev(dev)) {
If you move the ifdef into the if statement, the if statement can have
an else-branch that assigns params->ifindex, so you don't need the
restore dance (see below).
> + struct net_device *real_dev = vlan_dev_priv(dev)->real_dev;
> +
> + if (!is_vlan_dev(real_dev) &&
> + net_eq(dev_net(real_dev), dev_net(dev))) {
> + params->h_vlan_proto = vlan_dev_vlan_proto(dev);
> + params->h_vlan_TCI = htons(vlan_dev_vlan_id(dev));
> + params->ifindex = real_dev->ifindex;
> + } else {
> + return BPF_FIB_LKUP_RET_VLAN_FAILURE;
> + }
> + }
> +#endif
> +
> if (mtu)
> params->mtu_result = mtu; /* union with tot_len */
>
> @@ -6214,8 +6232,10 @@ static int bpf_fib_set_fwd_params(struct bpf_fib_lookup *params, u32 mtu)
>
> #if IS_ENABLED(CONFIG_INET)
> static int bpf_ipv4_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
> - u32 flags, bool check_mtu)
> + u32 flags, bool check_mtu,
> + struct net_device **fwd_dev)
> {
> + u32 in_ifindex = params->ifindex;
> struct neighbour *neigh = NULL;
> struct fib_nh_common *nhc;
> struct in_device *in_dev;
> @@ -6347,16 +6367,23 @@ static int bpf_ipv4_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
> memcpy(params->smac, dev->dev_addr, ETH_ALEN);
>
> set_fwd_params:
> - return bpf_fib_set_fwd_params(params, mtu);
> + if (fwd_dev)
> + *fwd_dev = dev;
> + err = bpf_fib_set_fwd_params(dev, params, flags, mtu);
> + if (err == BPF_FIB_LKUP_RET_VLAN_FAILURE)
> + params->ifindex = in_ifindex;
> + return err;
I think it's better to just move the assignment of params->ifindex
entirely into bpf_fib_set_fwd_params(), instead of this restore dance.
That way this can be simplified to:
err = bpf_fib_set_fwd_params(dev, params, flags, mtu);
if (!err && fwd_dev)
*fwd_dev = dev;
return err;
> }
> #endif
>
> #if IS_ENABLED(CONFIG_IPV6)
> static int bpf_ipv6_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
> - u32 flags, bool check_mtu)
> + u32 flags, bool check_mtu,
> + struct net_device **fwd_dev)
> {
> struct in6_addr *src = (struct in6_addr *) params->ipv6_src;
> struct in6_addr *dst = (struct in6_addr *) params->ipv6_dst;
> + u32 in_ifindex = params->ifindex;
> struct fib6_result res = {};
> struct neighbour *neigh;
> struct net_device *dev;
> @@ -6486,13 +6513,19 @@ static int bpf_ipv6_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
> memcpy(params->smac, dev->dev_addr, ETH_ALEN);
>
> set_fwd_params:
> - return bpf_fib_set_fwd_params(params, mtu);
> + if (fwd_dev)
> + *fwd_dev = dev;
> + err = bpf_fib_set_fwd_params(dev, params, flags, mtu);
> + if (err == BPF_FIB_LKUP_RET_VLAN_FAILURE)
> + params->ifindex = in_ifindex;
> + return err;
Same as above.
-Toke
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH bpf-next v4 2/3] bpf: Add BPF_FIB_LOOKUP_VLAN_INPUT flag to bpf_fib_lookup() helper
2026-06-23 2:51 ` [PATCH bpf-next v4 2/3] bpf: Add BPF_FIB_LOOKUP_VLAN_INPUT " Avinash Duduskar
@ 2026-06-23 12:00 ` Toke Høiland-Jørgensen
0 siblings, 0 replies; 10+ messages in thread
From: Toke Høiland-Jørgensen @ 2026-06-23 12:00 UTC (permalink / raw)
To: Avinash Duduskar, ast, daniel, andrii
Cc: eddyz87, memxor, martin.lau, song, yonghong.song, jolsa, emil,
john.fastabend, sdf, davem, edumazet, kuba, pabeni, horms, shuah,
hawk, yatsenko, leon.hwang, kpsingh, a.s.protopopov, ameryhung,
rongtao, eyal.birger, bpf, netdev, linux-kernel, linux-kselftest,
dsahern
Avinash Duduskar <avinash.duduskar@gmail.com> writes:
> 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 the flag 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>
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH bpf-next v4 3/3] selftests/bpf: Add bpf_fib_lookup() VLAN flag tests
2026-06-23 2:51 ` [PATCH bpf-next v4 3/3] selftests/bpf: Add bpf_fib_lookup() VLAN flag tests Avinash Duduskar
2026-06-23 3:39 ` bot+bpf-ci
@ 2026-06-23 12:36 ` kernel test robot
1 sibling, 0 replies; 10+ messages in thread
From: kernel test robot @ 2026-06-23 12:36 UTC (permalink / raw)
To: Avinash Duduskar, ast, daniel, andrii
Cc: llvm, oe-kbuild-all, eddyz87, memxor, martin.lau, song,
yonghong.song, jolsa, emil, john.fastabend, sdf, davem, edumazet,
kuba, pabeni, horms, shuah, hawk, yatsenko, leon.hwang, kpsingh,
a.s.protopopov, ameryhung, rongtao, eyal.birger, bpf, netdev,
linux-kernel, linux-kselftest
Hi Avinash,
kernel test robot noticed the following build warnings:
[auto build test WARNING on a975094bf98ca97be9146f9d3b5681a6f9cf5ce3]
url: https://github.com/intel-lab-lkp/linux/commits/Avinash-Duduskar/bpf-Add-BPF_FIB_LOOKUP_VLAN-flag-to-bpf_fib_lookup-helper/20260623-105336
base: a975094bf98ca97be9146f9d3b5681a6f9cf5ce3
patch link: https://lore.kernel.org/r/20260623025147.1001664-4-avinash.duduskar%40gmail.com
patch subject: [PATCH bpf-next v4 3/3] selftests/bpf: Add bpf_fib_lookup() VLAN flag tests
config: i386-buildonly-randconfig-006-20260623 (https://download.01.org/0day-ci/archive/20260623/202606232057.G1fSw98N-lkp@intel.com/config)
compiler: clang version 22.1.3 (https://github.com/llvm/llvm-project e9846648fd6183ee6d8cbdb4502213fcf902a211)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260623/202606232057.G1fSw98N-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202606232057.G1fSw98N-lkp@intel.com/
All warnings (new ones prefixed by >>):
>> net/core/filter.c:6567:14: warning: unused variable 'net' [-Wunused-variable]
6567 | struct net *net = dev_net(skb->dev);
| ^~~
1 warning generated.
vim +/net +6567 net/core/filter.c
87f5fc7e48dd31 David Ahern 2018-05-09 6563
87f5fc7e48dd31 David Ahern 2018-05-09 6564 BPF_CALL_4(bpf_skb_fib_lookup, struct sk_buff *, skb,
87f5fc7e48dd31 David Ahern 2018-05-09 6565 struct bpf_fib_lookup *, params, int, plen, u32, flags)
87f5fc7e48dd31 David Ahern 2018-05-09 6566 {
4f74fede40df8d David Ahern 2018-05-21 @6567 struct net *net = dev_net(skb->dev);
f392520e15094e Avinash Duduskar 2026-06-23 6568 struct net_device *fwd_dev = NULL;
4c79579b44b187 David Ahern 2018-06-26 6569 int rc = -EAFNOSUPPORT;
2c0a10af688c02 Jesper Dangaard Brouer 2021-02-09 6570 bool check_mtu = false;
4f74fede40df8d David Ahern 2018-05-21 6571
87f5fc7e48dd31 David Ahern 2018-05-09 6572 if (plen < sizeof(*params))
87f5fc7e48dd31 David Ahern 2018-05-09 6573 return -EINVAL;
87f5fc7e48dd31 David Ahern 2018-05-09 6574
31de4105f00d64 Martin KaFai Lau 2023-02-17 6575 if (flags & ~BPF_FIB_LOOKUP_MASK)
9ce64f192d161a David Ahern 2018-05-29 6576 return -EINVAL;
9ce64f192d161a David Ahern 2018-05-29 6577
2c0a10af688c02 Jesper Dangaard Brouer 2021-02-09 6578 if (params->tot_len)
2c0a10af688c02 Jesper Dangaard Brouer 2021-02-09 6579 check_mtu = true;
2c0a10af688c02 Jesper Dangaard Brouer 2021-02-09 6580
87f5fc7e48dd31 David Ahern 2018-05-09 6581 switch (params->family) {
87f5fc7e48dd31 David Ahern 2018-05-09 6582 #if IS_ENABLED(CONFIG_INET)
87f5fc7e48dd31 David Ahern 2018-05-09 6583 case AF_INET:
f392520e15094e Avinash Duduskar 2026-06-23 6584 rc = bpf_ipv4_fib_lookup(net, params, flags, check_mtu,
f392520e15094e Avinash Duduskar 2026-06-23 6585 &fwd_dev);
4f74fede40df8d David Ahern 2018-05-21 6586 break;
87f5fc7e48dd31 David Ahern 2018-05-09 6587 #endif
87f5fc7e48dd31 David Ahern 2018-05-09 6588 #if IS_ENABLED(CONFIG_IPV6)
87f5fc7e48dd31 David Ahern 2018-05-09 6589 case AF_INET6:
f392520e15094e Avinash Duduskar 2026-06-23 6590 rc = bpf_ipv6_fib_lookup(net, params, flags, check_mtu,
f392520e15094e Avinash Duduskar 2026-06-23 6591 &fwd_dev);
4f74fede40df8d David Ahern 2018-05-21 6592 break;
87f5fc7e48dd31 David Ahern 2018-05-09 6593 #endif
87f5fc7e48dd31 David Ahern 2018-05-09 6594 }
4f74fede40df8d David Ahern 2018-05-21 6595
2c0a10af688c02 Jesper Dangaard Brouer 2021-02-09 6596 if (rc == BPF_FIB_LKUP_RET_SUCCESS && !check_mtu) {
f392520e15094e Avinash Duduskar 2026-06-23 6597 /* without tot_len, check the skb against the FIB-result
f392520e15094e Avinash Duduskar 2026-06-23 6598 * device's MTU
2c0a10af688c02 Jesper Dangaard Brouer 2021-02-09 6599 */
f392520e15094e Avinash Duduskar 2026-06-23 6600 if (!is_skb_forwardable(fwd_dev, skb))
4c79579b44b187 David Ahern 2018-06-26 6601 rc = BPF_FIB_LKUP_RET_FRAG_NEEDED;
e1850ea9bd9eca Jesper Dangaard Brouer 2021-02-09 6602
f392520e15094e Avinash Duduskar 2026-06-23 6603 params->mtu_result = fwd_dev->mtu; /* union with tot_len */
4f74fede40df8d David Ahern 2018-05-21 6604 }
4f74fede40df8d David Ahern 2018-05-21 6605
4c79579b44b187 David Ahern 2018-06-26 6606 return rc;
87f5fc7e48dd31 David Ahern 2018-05-09 6607 }
87f5fc7e48dd31 David Ahern 2018-05-09 6608
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH bpf-next v4 1/3] bpf: Add BPF_FIB_LOOKUP_VLAN flag to bpf_fib_lookup() helper
2026-06-23 11:58 ` Toke Høiland-Jørgensen
@ 2026-06-23 18:28 ` Avinash Duduskar
2026-06-23 19:45 ` Toke Høiland-Jørgensen
0 siblings, 1 reply; 10+ messages in thread
From: Avinash Duduskar @ 2026-06-23 18:28 UTC (permalink / raw)
To: Toke Høiland-Jørgensen, ast, daniel, andrii
Cc: eddyz87, memxor, martin.lau, song, yonghong.song, jolsa, emil,
john.fastabend, sdf, davem, edumazet, kuba, pabeni, horms, shuah,
hawk, yatsenko, leon.hwang, kpsingh, a.s.protopopov, ameryhung,
rongtao, eyal.birger, bpf, netdev, linux-kernel, linux-kselftest,
dsahern
Toke Høiland-Jørgensen <toke@redhat.com> writes:
> I think it's better to just move the assignment of params->ifindex
> entirely into bpf_fib_set_fwd_params(), instead of this restore dance.
> That way this can be simplified to:
>
> err = bpf_fib_set_fwd_params(dev, params, flags, mtu);
> if (!err && fwd_dev)
> *fwd_dev = dev;
> return err;
The caller-side restore is ungainly, agreed, but the assignment can't move
all the way into the helper. The early params->ifindex = dev->ifindex
sits above the neighbour lookup on purpose: that is d1c362e1dd68a
("bpf: Always return target ifindex in bpf_fib_lookup"), which took it
out of bpf_fib_set_fwd_params() and put it there so a program still
gets the target ifindex on the BPF_FIB_LKUP_RET_NO_NEIGH path and can
bpf_redirect_neigh() on it. bpf_fib_set_fwd_params() is called only at
the set_fwd_params label, below the NO_NEIGH return (and below the IPv6
NO_SRC_ADDR return), so an assignment living in the helper never runs
on those paths and params->ifindex falls back to the input. That would
change the reported ifindex for plain bpf_fib_lookup() callers hitting
NO_NEIGH, not only the VLAN ones.
I can still get the caller down to your form by keeping the early write
and moving just the VLAN_FAILURE rewind into the helper, with one extra
parameter, the input ifindex saved before the egress write:
err = bpf_fib_set_fwd_params(dev, params, flags, mtu, in_ifindex);
if (!err && fwd_dev)
*fwd_dev = dev;
return err;
and the helper owning the rewind in the unreducible branch:
} else {
params->ifindex = in_ifindex;
return BPF_FIB_LKUP_RET_VLAN_FAILURE;
}
So the restore leaves the caller; the early egress write stays because
NO_NEIGH and NO_SRC_ADDR depend on it.
3/3 adds a NO_NEIGH arm that pins the egress ifindex (input != egress):
with the assignment moved into the helper, that case reports the input
ifindex instead, while the return code stays NO_NEIGH, only the ifindex
flips. It passes with the early write kept.
> If you move the ifdef into the if statement, the if statement can have
> an else-branch that assigns params->ifindex, so you don't need the
> restore dance (see below).
Same constraint: an else-branch inside bpf_fib_set_fwd_params() only
runs when the helper runs, which is never on the NO_NEIGH/NO_SRC_ADDR
returns, so it cannot be the sole writer of the egress ifindex.
Does the in_ifindex version look right to you? The alternative is to
route the error returns through the label so the assignment can live
fully in the helper; threading the return codes back through it works,
but it is its own kind of dance and reads worse to me.
Thanks,
Avinash
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH bpf-next v4 1/3] bpf: Add BPF_FIB_LOOKUP_VLAN flag to bpf_fib_lookup() helper
2026-06-23 18:28 ` Avinash Duduskar
@ 2026-06-23 19:45 ` Toke Høiland-Jørgensen
0 siblings, 0 replies; 10+ messages in thread
From: Toke Høiland-Jørgensen @ 2026-06-23 19:45 UTC (permalink / raw)
To: Avinash Duduskar, ast, daniel, andrii
Cc: eddyz87, memxor, martin.lau, song, yonghong.song, jolsa, emil,
john.fastabend, sdf, davem, edumazet, kuba, pabeni, horms, shuah,
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Avinash Duduskar <avinash.duduskar@gmail.com> writes:
> Toke Høiland-Jørgensen <toke@redhat.com> writes:
>
>> I think it's better to just move the assignment of params->ifindex
>> entirely into bpf_fib_set_fwd_params(), instead of this restore dance.
>> That way this can be simplified to:
>>
>> err = bpf_fib_set_fwd_params(dev, params, flags, mtu);
>> if (!err && fwd_dev)
>> *fwd_dev = dev;
>> return err;
>
> The caller-side restore is ungainly, agreed, but the assignment can't move
> all the way into the helper. The early params->ifindex = dev->ifindex
> sits above the neighbour lookup on purpose: that is d1c362e1dd68a
> ("bpf: Always return target ifindex in bpf_fib_lookup"), which took it
> out of bpf_fib_set_fwd_params() and put it there so a program still
> gets the target ifindex on the BPF_FIB_LKUP_RET_NO_NEIGH path and can
> bpf_redirect_neigh() on it. bpf_fib_set_fwd_params() is called only at
> the set_fwd_params label, below the NO_NEIGH return (and below the IPv6
> NO_SRC_ADDR return), so an assignment living in the helper never runs
> on those paths and params->ifindex falls back to the input. That would
> change the reported ifindex for plain bpf_fib_lookup() callers hitting
> NO_NEIGH, not only the VLAN ones.
Right. Well, seems I forgot about that patch, even though I seem to have
written it :)
> I can still get the caller down to your form by keeping the early write
> and moving just the VLAN_FAILURE rewind into the helper, with one extra
> parameter, the input ifindex saved before the egress write:
>
> err = bpf_fib_set_fwd_params(dev, params, flags, mtu, in_ifindex);
> if (!err && fwd_dev)
> *fwd_dev = dev;
> return err;
>
> and the helper owning the rewind in the unreducible branch:
>
> } else {
> params->ifindex = in_ifindex;
> return BPF_FIB_LKUP_RET_VLAN_FAILURE;
> }
OK, if we do need to restore it, I think it's better to do it there.
Also, wrt the fwd_dev parameter: Do we really have a use case from using
this from TC? In TC you can just redirect to the VLAN device; this is
meant for XDP which can't do that. So how about we just reject the flag
on the TC side, and get rid of the fwd_dev parameter entirely?
If we do that we're back to just a plain 'return bpf_fib_set_fwd_params()' :)
-Toke
^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2026-06-23 19:45 UTC | newest]
Thread overview: 10+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-06-23 2:51 [PATCH bpf-next v4 0/3] bpf: bidirectional VLAN support for bpf_fib_lookup() Avinash Duduskar
2026-06-23 2:51 ` [PATCH bpf-next v4 1/3] bpf: Add BPF_FIB_LOOKUP_VLAN flag to bpf_fib_lookup() helper Avinash Duduskar
2026-06-23 11:58 ` Toke Høiland-Jørgensen
2026-06-23 18:28 ` Avinash Duduskar
2026-06-23 19:45 ` Toke Høiland-Jørgensen
2026-06-23 2:51 ` [PATCH bpf-next v4 2/3] bpf: Add BPF_FIB_LOOKUP_VLAN_INPUT " Avinash Duduskar
2026-06-23 12:00 ` Toke Høiland-Jørgensen
2026-06-23 2:51 ` [PATCH bpf-next v4 3/3] selftests/bpf: Add bpf_fib_lookup() VLAN flag tests Avinash Duduskar
2026-06-23 3:39 ` bot+bpf-ci
2026-06-23 12:36 ` kernel test robot
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