From: Dave Marchevsky <davemarchevsky@xxxxxx>
ARG_PTR_TO_KPTR is currently only used by the bpf_kptr_xchg helper.
Although it limits reg types for that helper's first arg to
PTR_TO_MAP_VALUE, any arbitrary mapval won't do: further custom
verification logic ensures that the mapval reg being xchgd-into is
pointing to a kptr field. If this is not the case, it's not safe to xchg
into that reg's pointee.
Let's rename the bpf_arg_type to more accurately describe the fairly
specific expectations that this arg type encodes.
This is a nonfunctional change.
Signed-off-by: Dave Marchevsky <davemarchevsky@xxxxxx>
Signed-off-by: Amery Hung <amery.hung@xxxxxxxxxxxxx>
---
include/linux/bpf.h | 2 +-
kernel/bpf/helpers.c | 2 +-
kernel/bpf/verifier.c | 6 +++---
3 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 7ad37cbdc815..f853e350c057 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -744,7 +744,7 @@ enum bpf_arg_type {
ARG_PTR_TO_STACK, /* pointer to stack */
ARG_PTR_TO_CONST_STR, /* pointer to a null terminated read-only string */
ARG_PTR_TO_TIMER, /* pointer to bpf_timer */
- ARG_PTR_TO_KPTR, /* pointer to referenced kptr */
+ ARG_KPTR_XCHG_DEST, /* pointer to destination that kptrs are bpf_kptr_xchg'd into */
ARG_PTR_TO_DYNPTR, /* pointer to bpf_dynptr. See bpf_type_flag for dynptr type */
__BPF_ARG_TYPE_MAX,
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index d02ae323996b..8ecd8dc95f16 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -1636,7 +1636,7 @@ static const struct bpf_func_proto bpf_kptr_xchg_proto = {
.gpl_only = false,
.ret_type = RET_PTR_TO_BTF_ID_OR_NULL,
.ret_btf_id = BPF_PTR_POISON,
- .arg1_type = ARG_PTR_TO_KPTR,
+ .arg1_type = ARG_KPTR_XCHG_DEST,
.arg2_type = ARG_PTR_TO_BTF_ID_OR_NULL | OBJ_RELEASE,
.arg2_btf_id = BPF_PTR_POISON,
};
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 1f5302fb0957..9f2964b13b46 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -8399,7 +8399,7 @@ static const struct bpf_reg_types func_ptr_types = { .types = { PTR_TO_FUNC } };
static const struct bpf_reg_types stack_ptr_types = { .types = { PTR_TO_STACK } };
static const struct bpf_reg_types const_str_ptr_types = { .types = { PTR_TO_MAP_VALUE } };
static const struct bpf_reg_types timer_types = { .types = { PTR_TO_MAP_VALUE } };
-static const struct bpf_reg_types kptr_types = { .types = { PTR_TO_MAP_VALUE } };
+static const struct bpf_reg_types kptr_xchg_dest_types = { .types = { PTR_TO_MAP_VALUE } };
static const struct bpf_reg_types dynptr_types = {
.types = {
PTR_TO_STACK,
@@ -8431,7 +8431,7 @@ static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = {
[ARG_PTR_TO_STACK] = &stack_ptr_types,
[ARG_PTR_TO_CONST_STR] = &const_str_ptr_types,
[ARG_PTR_TO_TIMER] = &timer_types,
- [ARG_PTR_TO_KPTR] = &kptr_types,
+ [ARG_KPTR_XCHG_DEST] = &kptr_xchg_dest_types,
[ARG_PTR_TO_DYNPTR] = &dynptr_types,
};
@@ -9031,7 +9031,7 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
return err;
break;
}
- case ARG_PTR_TO_KPTR:
+ case ARG_KPTR_XCHG_DEST:
err = process_kptr_func(env, regno, meta);
if (err)
return err;
--
2.20.1
