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| author | Dave Marchevsky <davemarchevsky@fb.com> | 2022-09-09 02:07:16 +0300 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2022-09-11 04:14:50 +0300 |
| commit | 1bfe26fb082724be453e4d7fd9bb358e3ba669b2 (patch) | |
| tree | 9be8bce26275c1cc62d3f683cc64f2e247da96a2 /include/linux/bpf_verifier.h | |
| parent | f7c946f288e32fd8b5fd69825683420d473672bd (diff) | |
| download | linux-1bfe26fb082724be453e4d7fd9bb358e3ba669b2.tar.xz | |
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 <davemarchevsky@fb.com>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20220908230716.2751723-1-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'include/linux/bpf_verifier.h')
| -rw-r--r-- | include/linux/bpf_verifier.h | 1 |
1 files changed, 1 insertions, 0 deletions
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() */ |