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bpf: introduce must_not_sleep helper flag #10046

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bpf: introduce must_not_sleep helper flag #10046

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1 change: 1 addition & 0 deletions include/linux/bpf.h
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Original file line number Diff line number Diff line change
Expand Up @@ -940,6 +940,7 @@ struct bpf_func_proto {
};
int *ret_btf_id; /* return value btf_id */
bool (*allowed)(const struct bpf_prog *prog);
bool must_not_sleep;
};

/* bpf_context is intentionally undefined structure. Pointer to bpf_context is
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1 change: 1 addition & 0 deletions kernel/bpf/task_iter.c
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Expand Up @@ -792,6 +792,7 @@ const struct bpf_func_proto bpf_find_vma_proto = {
.arg3_type = ARG_PTR_TO_FUNC,
.arg4_type = ARG_PTR_TO_STACK_OR_NULL,
.arg5_type = ARG_ANYTHING,
.must_not_sleep = false,
};

struct bpf_iter_task_vma_kern_data {
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5 changes: 5 additions & 0 deletions kernel/bpf/verifier.c
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Expand Up @@ -11431,6 +11431,11 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
return -EINVAL;
}

if (in_sleepable(env) && fn->must_not_sleep) {
verbose(env, "helper call must not sleep, but called in a sleepable prog\n");
return -EINVAL;
}

/* With LD_ABS/IND some JITs save/restore skb from r1. */
changes_data = bpf_helper_changes_pkt_data(func_id);
if (changes_data && fn->arg1_type != ARG_PTR_TO_CTX) {
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