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bpf: Allow bpf_for/bpf_repeat calls while holding a spinlock

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Add the bpf_iter_num_* kfuncs called by bpf_for in special_kfunc_list,
 and allow the calls even while holding a spin lock.

Signed-off-by: Emil Tsalapatis (Meta) <emil@etsalapatis.com>
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250104202528.882482-2-emil@etsalapatis.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Emil Tsalapatis 2025-01-04 15:25:27 -05:00 committed by Alexei Starovoitov
parent 2532608530
commit 512816403e
1 changed files with 19 additions and 1 deletions
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20
kernel/bpf/verifier.c
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@ -11690,6 +11690,9 @@ enum special_kfunc_type {
KF_bpf_get_kmem_cache,
KF_bpf_local_irq_save,
KF_bpf_local_irq_restore,
KF_bpf_iter_num_new,
KF_bpf_iter_num_next,
KF_bpf_iter_num_destroy,
};
BTF_SET_START(special_kfunc_set)
@ -11765,6 +11768,9 @@ BTF_ID_UNUSED
BTF_ID(func, bpf_get_kmem_cache)
BTF_ID(func, bpf_local_irq_save)
BTF_ID(func, bpf_local_irq_restore)
BTF_ID(func, bpf_iter_num_new)
BTF_ID(func, bpf_iter_num_next)
BTF_ID(func, bpf_iter_num_destroy)
static bool is_kfunc_ret_null(struct bpf_kfunc_call_arg_meta *meta)
{
@ -12151,12 +12157,24 @@ static bool is_bpf_rbtree_api_kfunc(u32 btf_id)
btf_id == special_kfunc_list[KF_bpf_rbtree_first];
}
static bool is_bpf_iter_num_api_kfunc(u32 btf_id)
{
return btf_id == special_kfunc_list[KF_bpf_iter_num_new] ||
btf_id == special_kfunc_list[KF_bpf_iter_num_next] ||
btf_id == special_kfunc_list[KF_bpf_iter_num_destroy];
}
static bool is_bpf_graph_api_kfunc(u32 btf_id)
{
return is_bpf_list_api_kfunc(btf_id) || is_bpf_rbtree_api_kfunc(btf_id) ||
btf_id == special_kfunc_list[KF_bpf_refcount_acquire_impl];
}
static bool kfunc_spin_allowed(u32 btf_id)
{
return is_bpf_graph_api_kfunc(btf_id) || is_bpf_iter_num_api_kfunc(btf_id);
}
static bool is_sync_callback_calling_kfunc(u32 btf_id)
{
return btf_id == special_kfunc_list[KF_bpf_rbtree_add_impl];
@ -19048,7 +19066,7 @@ static int do_check(struct bpf_verifier_env *env)
if (env->cur_state->active_locks) {
if ((insn->src_reg == BPF_REG_0 && insn->imm != BPF_FUNC_spin_unlock) ||
(insn->src_reg == BPF_PSEUDO_KFUNC_CALL &&
(insn->off != 0 || !is_bpf_graph_api_kfunc(insn->imm)))) {
(insn->off != 0 || !kfunc_spin_allowed(insn->imm)))) {
verbose(env, "function calls are not allowed while holding a lock\n");
return -EINVAL;
}