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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 /kernel/bpf
parent3d717fad5081b8e3bda76d86907fad95398cbde8 (diff)
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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 'kernel/bpf')
-rw-r--r--kernel/bpf/arraymap.c7
-rw-r--r--kernel/bpf/hashtab.c7
-rw-r--r--kernel/bpf/helpers.c5
3 files changed, 8 insertions, 11 deletions
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index cebd4fb06d19..5e1ccfae916b 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -645,7 +645,7 @@ static const struct bpf_iter_seq_info iter_seq_info = {
.seq_priv_size = sizeof(struct bpf_iter_seq_array_map_info),
};
-static int bpf_for_each_array_elem(struct bpf_map *map, void *callback_fn,
+static int bpf_for_each_array_elem(struct bpf_map *map, bpf_callback_t callback_fn,
void *callback_ctx, u64 flags)
{
u32 i, key, num_elems = 0;
@@ -668,9 +668,8 @@ static int bpf_for_each_array_elem(struct bpf_map *map, void *callback_fn,
val = array->value + array->elem_size * i;
num_elems++;
key = i;
- ret = BPF_CAST_CALL(callback_fn)((u64)(long)map,
- (u64)(long)&key, (u64)(long)val,
- (u64)(long)callback_ctx, 0);
+ ret = callback_fn((u64)(long)map, (u64)(long)&key,
+ (u64)(long)val, (u64)(long)callback_ctx, 0);
/* return value: 0 - continue, 1 - stop and return */
if (ret)
break;
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 3d8f9d6997d5..d29af9988f37 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -2049,7 +2049,7 @@ static const struct bpf_iter_seq_info iter_seq_info = {
.seq_priv_size = sizeof(struct bpf_iter_seq_hash_map_info),
};
-static int bpf_for_each_hash_elem(struct bpf_map *map, void *callback_fn,
+static int bpf_for_each_hash_elem(struct bpf_map *map, bpf_callback_t callback_fn,
void *callback_ctx, u64 flags)
{
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
@@ -2089,9 +2089,8 @@ static int bpf_for_each_hash_elem(struct bpf_map *map, void *callback_fn,
val = elem->key + roundup_key_size;
}
num_elems++;
- ret = BPF_CAST_CALL(callback_fn)((u64)(long)map,
- (u64)(long)key, (u64)(long)val,
- (u64)(long)callback_ctx, 0);
+ ret = callback_fn((u64)(long)map, (u64)(long)key,
+ (u64)(long)val, (u64)(long)callback_ctx, 0);
/* return value: 0 - continue, 1 - stop and return */
if (ret) {
rcu_read_unlock();
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 2c604ff8c7fb..1ffd469c217f 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -1056,7 +1056,7 @@ static enum hrtimer_restart bpf_timer_cb(struct hrtimer *hrtimer)
struct bpf_hrtimer *t = container_of(hrtimer, struct bpf_hrtimer, timer);
struct bpf_map *map = t->map;
void *value = t->value;
- void *callback_fn;
+ bpf_callback_t callback_fn;
void *key;
u32 idx;
@@ -1081,8 +1081,7 @@ static enum hrtimer_restart bpf_timer_cb(struct hrtimer *hrtimer)
key = value - round_up(map->key_size, 8);
}
- BPF_CAST_CALL(callback_fn)((u64)(long)map, (u64)(long)key,
- (u64)(long)value, 0, 0);
+ callback_fn((u64)(long)map, (u64)(long)key, (u64)(long)value, 0, 0);
/* The verifier checked that return value is zero. */
this_cpu_write(hrtimer_running, NULL);