diff options
| author | John Fastabend <john.fastabend@gmail.com> | 2020-06-24 15:20:39 -0700 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2020-06-25 16:17:05 +0200 |
| commit | a9b59159d338d414acaa8e2f569d129d51c76452 (patch) | |
| tree | b02a3af3bee5967515fb0ca85d736b83b975f897 /include | |
| parent | bcc7f554cfa7e0ac77c7adc4027c16f4a2f99c6f (diff) | |
bpf: Do not allow btf_ctx_access with __int128 types
To ensure btf_ctx_access() is safe the verifier checks that the BTF
arg type is an int, enum, or pointer. When the function does the
BTF arg lookup it uses the calculation 'arg = off / 8' using the
fact that registers are 8B. This requires that the first arg is
in the first reg, the second in the second, and so on. However,
for __int128 the arg will consume two registers by default LLVM
implementation. So this will cause the arg layout assumed by the
'arg = off / 8' calculation to be incorrect.
Because __int128 is uncommon this patch applies the easiest fix and
will force int types to be sizeof(u64) or smaller so that they will
fit in a single register.
v2: remove unneeded parens per Andrii's feedback
Fixes: 9e15db66136a1 ("bpf: Implement accurate raw_tp context access via BTF")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/159303723962.11287.13309537171132420717.stgit@john-Precision-5820-Tower
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/btf.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/btf.h b/include/linux/btf.h index 5c1ea99b480f..8b81fbb4497c 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -82,6 +82,11 @@ static inline bool btf_type_is_int(const struct btf_type *t) return BTF_INFO_KIND(t->info) == BTF_KIND_INT; } +static inline bool btf_type_is_small_int(const struct btf_type *t) +{ + return btf_type_is_int(t) && t->size <= sizeof(u64); +} + static inline bool btf_type_is_enum(const struct btf_type *t) { return BTF_INFO_KIND(t->info) == BTF_KIND_ENUM; |