From b5a4aa31abd6fe90009b63e35dc18c67d041ec0c Mon Sep 17 00:00:00 2001 From: Shakeel Butt Date: Thu, 1 Oct 2026 07:19:01 -0700 Subject: [PATCH] bpf, cgroup: Fix cgroup struct_ops query for a second attach type Two things in __cgroup_bpf_query() work only because CGROUP_TCP_SOCK_OPS is the only struct_ops attach type. It calls cgroup_bpf_enabled(atype) with an atype that find_atype_by_struct_ops_id() works out at runtime. That macro is an asm goto and needs a constant. Today the compiler can see there is only one value; add a second type and the build breaks with "impossible constraint in 'asm'". The check is not needed anyway. When the key is off nothing is attached, so progs[atype] and effective[atype] are empty and the count loop leaves total_cnt at 0. The other attach types already use that loop with no such check. Drop the check and the skip_count label. And find_atype_by_struct_ops_id() matches on type_id alone. An attach type whose subsystem is not built keeps type_id 0, so a query for type 0 finds it and returns success with nothing instead of -ENOENT. Skip such slots. Fixes: 369d9dcd8fb8 ("bpf: Add infrastructure to support attaching struct_ops to cgroups") Signed-off-by: Shakeel Butt Signed-off-by: Alexei Starovoitov Reviewed-by: Amery Hung Acked-by: Yafang Shao Acked-by: Tejun Heo Link: https://patch.msgid.link/20261001141901.3225830-1-shakeel.butt@linux.dev --- kernel/bpf/cgroup.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c index 2bbe77de89f0..ce82963bcfc7 100644 --- a/kernel/bpf/cgroup.c +++ b/kernel/bpf/cgroup.c @@ -45,6 +45,7 @@ static enum cgroup_bpf_attach_type find_atype_by_struct_ops_id(u32 type_id) for (atype = 0; atype < MAX_CGROUP_BPF_ATTACH_TYPE; atype++) { if (cgroup_bpf_is_struct_ops_atype(atype) && + cgroup_struct_ops[atype].type_id && cgroup_struct_ops[atype].type_id == type_id) return atype; } @@ -1448,8 +1449,6 @@ static int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr, return -ENOENT; from_atype = to_atype = atype; flags = 0; - if (!cgroup_bpf_enabled(atype)) - goto skip_count; } else if (type == BPF_LSM_CGROUP) { if (!effective_query && attr->query.prog_cnt && prog_ids && !prog_attach_flags) @@ -1476,7 +1475,6 @@ static int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr, } } -skip_count: /* always output uattr->query.attach_flags as 0 during effective query */ flags = effective_query ? 0 : flags; if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))