Similarly to 5a52ae4e32a6 ("bpf: Allow to retrieve cgroup v1 classid
from v2 hooks"), add a helper to retrieve cgroup v1 classid solely
based on the skb->sk, so it can be used as key as part of BPF map
lookups out of tc from host ns, in particular given the skb->sk is
retained these days when crossing net ns thanks to 9c4c325252c5
("skbuff: preserve sock reference when scrubbing the skb."). This
is similar to bpf_skb_cgroup_id() which implements the same for v2.
Kubernetes ecosystem is still operating on v1 however, hence net_cls
needs to be used there until this can be dropped in with the v2
helper of bpf_skb_cgroup_id().
Signed-off-by: Daniel Borkmann <dan...@iogearbox.net>
---
include/uapi/linux/bpf.h | 10 ++++++++++
net/core/filter.c | 21 +++++++++++++++++++++
tools/include/uapi/linux/bpf.h | 10 ++++++++++
3 files changed, 41 insertions(+)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 2b1d3f16cbd1..6116a7f54c8f 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -3643,6 +3643,15 @@ union bpf_attr {
* *flags* are identical to those used for bpf_snprintf_btf.
* Return
* 0 on success or a negative error in case of failure.
+ *
+ * u64 bpf_skb_cgroup_classid(struct sk_buff *skb)
+ * Description
+ * See **bpf_get_cgroup_classid**\ () for the main description.
+ * This helper differs from **bpf_get_cgroup_classid**\ () in that
+ * the cgroup v1 net_cls class is retrieved only from the *skb*'s
+ * associated socket instead of the current process.
+ * Return
+ * The id is returned or 0 in case the id could not be retrieved.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -3796,6 +3805,7 @@ union bpf_attr {
FN(copy_from_user), \
FN(snprintf_btf), \
FN(seq_printf_btf), \
+ FN(skb_cgroup_classid), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
diff --git a/net/core/filter.c b/net/core/filter.c
index af88935e24b1..fa01c697977d 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2707,6 +2707,23 @@ static const struct bpf_func_proto
bpf_get_cgroup_classid_curr_proto = {
.gpl_only = false,
.ret_type = RET_INTEGER,
};
+
+BPF_CALL_1(bpf_skb_cgroup_classid, const struct sk_buff *, skb)
+{
+ struct sock *sk = skb_to_full_sk(skb);
+
+ if (!sk || !sk_fullsock(sk))
+ return 0;
+
+ return sock_cgroup_classid(&sk->sk_cgrp_data);
+}
+
+static const struct bpf_func_proto bpf_skb_cgroup_classid_proto = {
+ .func = bpf_skb_cgroup_classid,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+};
#endif
BPF_CALL_1(bpf_get_cgroup_classid, const struct sk_buff *, skb)
@@ -6772,6 +6789,10 @@ tc_cls_act_func_proto(enum bpf_func_id func_id, const
struct bpf_prog *prog)
case BPF_FUNC_skb_get_xfrm_state:
return &bpf_skb_get_xfrm_state_proto;
#endif
+#ifdef CONFIG_CGROUP_NET_CLASSID
+ case BPF_FUNC_skb_cgroup_classid:
+ return &bpf_skb_cgroup_classid_proto;
+#endif
#ifdef CONFIG_SOCK_CGROUP_DATA
case BPF_FUNC_skb_cgroup_id:
return &bpf_skb_cgroup_id_proto;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 2b1d3f16cbd1..6116a7f54c8f 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -3643,6 +3643,15 @@ union bpf_attr {
* *flags* are identical to those used for bpf_snprintf_btf.
* Return
* 0 on success or a negative error in case of failure.
+ *
+ * u64 bpf_skb_cgroup_classid(struct sk_buff *skb)
+ * Description
+ * See **bpf_get_cgroup_classid**\ () for the main description.
+ * This helper differs from **bpf_get_cgroup_classid**\ () in that
+ * the cgroup v1 net_cls class is retrieved only from the *skb*'s
+ * associated socket instead of the current process.
+ * Return
+ * The id is returned or 0 in case the id could not be retrieved.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -3796,6 +3805,7 @@ union bpf_attr {
FN(copy_from_user), \
FN(snprintf_btf), \
FN(seq_printf_btf), \
+ FN(skb_cgroup_classid), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
--
2.21.0
