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authorKees Cook <keescook@chromium.org>2021-09-28 16:09:46 -0700
committerAlexei Starovoitov <ast@kernel.org>2021-09-28 16:27:18 -0700
commit102acbacfd9a96d101abd96d1a7a5bf92b7c3e8e (patch)
tree18cfa723e40dbe24928faf0299bf0b90e8df9f43 /include
parent3d717fad5081b8e3bda76d86907fad95398cbde8 (diff)
bpf: Replace callers of BPF_CAST_CALL with proper function typedef
In order to keep ahead of cases in the kernel where Control Flow Integrity (CFI) may trip over function call casts, enabling -Wcast-function-type is helpful. To that end, BPF_CAST_CALL causes various warnings and is one of the last places in the kernel triggering this warning. For actual function calls, replace BPF_CAST_CALL() with a typedef, which captures the same details about the given function pointers. This change results in no object code difference. Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Gustavo A. R. Silva <gustavoars@kernel.org> Link: https://github.com/KSPP/linux/issues/20 Link: https://lore.kernel.org/lkml/CAEf4Bzb46=-J5Fxc3mMZ8JQPtK1uoE0q6+g6WPz53Cvx=CBEhw@mail.gmail.com Link: https://lore.kernel.org/bpf/20210928230946.4062144-3-keescook@chromium.org
Diffstat (limited to 'include')
-rw-r--r--include/linux/bpf.h4
-rw-r--r--include/linux/filter.h5
2 files changed, 3 insertions, 6 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index b6c45a6cbbba..19735d59230a 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -48,6 +48,7 @@ extern struct idr btf_idr;
extern spinlock_t btf_idr_lock;
extern struct kobject *btf_kobj;
+typedef u64 (*bpf_callback_t)(u64, u64, u64, u64, u64);
typedef int (*bpf_iter_init_seq_priv_t)(void *private_data,
struct bpf_iter_aux_info *aux);
typedef void (*bpf_iter_fini_seq_priv_t)(void *private_data);
@@ -142,7 +143,8 @@ struct bpf_map_ops {
int (*map_set_for_each_callback_args)(struct bpf_verifier_env *env,
struct bpf_func_state *caller,
struct bpf_func_state *callee);
- int (*map_for_each_callback)(struct bpf_map *map, void *callback_fn,
+ int (*map_for_each_callback)(struct bpf_map *map,
+ bpf_callback_t callback_fn,
void *callback_ctx, u64 flags);
/* BTF name and id of struct allocated by map_alloc */
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 6c247663d4ce..47f80adbe744 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -360,11 +360,6 @@ static inline bool insn_is_zext(const struct bpf_insn *insn)
.off = 0, \
.imm = TGT })
-/* Function call */
-
-#define BPF_CAST_CALL(x) \
- ((u64 (*)(u64, u64, u64, u64, u64))(x))
-
/* Convert function address to BPF immediate */
#define BPF_CALL_IMM(x) ((void *)(x) - (void *)__bpf_call_base)