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bpf: Mark cgroup_subsys_state->cgroup RCU safe

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Mark struct cgroup_subsys_state->cgroup as safe under RCU read lock. This
will enable accessing css->cgroup from a bpf css iterator.

Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/20250623063854.1896364-4-song@kernel.org
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Song Liu
2025-06-23 13:03:12 +02:00
committed by Christian Brauner
parent 535b070f4a
commit 1504d8c7c7
1 changed files with 5 additions and 0 deletions
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kernel/bpf/verifier.c
+5
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@@ -6993,6 +6993,10 @@ BTF_TYPE_SAFE_RCU(struct css_set) {
struct cgroup *dfl_cgrp;
};
BTF_TYPE_SAFE_RCU(struct cgroup_subsys_state) {
struct cgroup *cgroup;
};
/* RCU trusted: these fields are trusted in RCU CS and can be NULL */
BTF_TYPE_SAFE_RCU_OR_NULL(struct mm_struct) {
struct file __rcu *exe_file;
@@ -7043,6 +7047,7 @@ static bool type_is_rcu(struct bpf_verifier_env *env,
BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct task_struct));
BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct cgroup));
BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct css_set));
BTF_TYPE_EMIT(BTF_TYPE_SAFE_RCU(struct cgroup_subsys_state));
return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_rcu");
}