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authorJohn Fastabend <john.fastabend@gmail.com>2020-06-24 15:20:39 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2020-06-25 16:17:05 +0200
commita9b59159d338d414acaa8e2f569d129d51c76452 (patch)
treeb02a3af3bee5967515fb0ca85d736b83b975f897 /include/linux/btf.h
parentbcc7f554cfa7e0ac77c7adc4027c16f4a2f99c6f (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/linux/btf.h')
-rw-r--r--include/linux/btf.h5
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;