From 1bfe26fb082724be453e4d7fd9bb358e3ba669b2 Mon Sep 17 00:00:00 2001 From: Dave Marchevsky Date: Thu, 8 Sep 2022 16:07:16 -0700 Subject: bpf: Add verifier support for custom callback return range Verifier logic to confirm that a callback function returns 0 or 1 was added in commit 69c087ba6225b ("bpf: Add bpf_for_each_map_elem() helper"). At the time, callback return value was only used to continue or stop iteration. In order to support callbacks with a broader return value range, such as those added in rbtree series[0] and others, add a callback_ret_range to bpf_func_state. Verifier's helpers which set in_callback_fn will also set the new field, which the verifier will later use to check return value bounds. Default to tnum_range(0, 0) instead of using tnum_unknown as a sentinel value as the latter would prevent the valid range (0, U64_MAX) being used. Previous global default tnum_range(0, 1) is explicitly set for extant callback helpers. The change to global default was made after discussion around this patch in rbtree series [1], goal here is to make it more obvious that callback_ret_range should be explicitly set. [0]: lore.kernel.org/bpf/20220830172759.4069786-1-davemarchevsky@fb.com/ [1]: lore.kernel.org/bpf/20220830172759.4069786-2-davemarchevsky@fb.com/ Signed-off-by: Dave Marchevsky Reviewed-by: Stanislav Fomichev Link: https://lore.kernel.org/r/20220908230716.2751723-1-davemarchevsky@fb.com Signed-off-by: Alexei Starovoitov --- include/linux/bpf_verifier.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index b49a349cc6ae..e197f8fb27e2 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -248,6 +248,7 @@ struct bpf_func_state { */ u32 async_entry_cnt; bool in_callback_fn; + struct tnum callback_ret_range; bool in_async_callback_fn; /* The following fields should be last. See copy_func_state() */ -- cgit v1.2.3-59-g8ed1b