leandrof/linux
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

bpf: Replace callers of BPF_CAST_CALL with proper function typedef

Browse Source 
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
This commit is contained in:
Kees Cook
2021-09-28 16:09:46 -07:00
committed by Alexei Starovoitov
parent 3d717fad50
commit 102acbacfd
5 changed files with 11 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
kernel/bpf/arraymap.c
View File

@@ -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;

7
kernel/bpf/hashtab.c
View File

@@ -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();

5
kernel/bpf/helpers.c
View File

@@ -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);