Add two new helper functions: bpf_dynptr_is_null and
bpf_dynptr_is_rdonly.
bpf_dynptr_is_null returns true if the dynptr is null / invalid
(determined by whether ptr->data is NULL), else false if
the dynptr is a valid dynptr.
bpf_dynptr_is_rdonly returns true if the dynptr is read-only,
else false if the dynptr is read-writable.
Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx>
---
include/uapi/linux/bpf.h | 20 ++++++++++++++++++
kernel/bpf/helpers.c | 37 +++++++++++++++++++++++++++++++---
scripts/bpf_doc.py | 3 +++
tools/include/uapi/linux/bpf.h | 20 ++++++++++++++++++
4 files changed, 77 insertions(+), 3 deletions(-)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 3b054553be30..90b6d0744df2 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5467,6 +5467,24 @@ union bpf_attr {
* Return
* 0 on success, -EINVAL if the dynptr is invalid, -ERANGE if
* trying to trim more bytes than the size of the dynptr.
+ *
+ * bool bpf_dynptr_is_null(struct bpf_dynptr *ptr)
+ * Description
+ * Determine whether a dynptr is null / invalid.
+ *
+ * *ptr* must be an initialized dynptr.
+ * Return
+ * True if the dynptr is null, else false.
+ *
+ * bool bpf_dynptr_is_rdonly(struct bpf_dynptr *ptr)
+ * Description
+ * Determine whether a dynptr is read-only.
+ *
+ * *ptr* must be an initialized dynptr. If *ptr*
+ * is a null dynptr, this will return false.
+ * Return
+ * True if the dynptr is read-only and a valid dynptr,
+ * else false.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -5683,6 +5701,8 @@ union bpf_attr {
FN(dynptr_data_rdonly), \
FN(dynptr_advance), \
FN(dynptr_trim), \
+ FN(dynptr_is_null), \
+ FN(dynptr_is_rdonly), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 9f356105ab49..8729383d0966 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -1398,7 +1398,7 @@ static const struct bpf_func_proto bpf_kptr_xchg_proto = {
#define DYNPTR_SIZE_MASK 0xFFFFFF
#define DYNPTR_RDONLY_BIT BIT(31)
-static bool bpf_dynptr_is_rdonly(struct bpf_dynptr_kern *ptr)
+static bool __bpf_dynptr_is_rdonly(struct bpf_dynptr_kern *ptr)
{
return ptr->size & DYNPTR_RDONLY_BIT;
}
@@ -1539,7 +1539,7 @@ BPF_CALL_5(bpf_dynptr_write, struct bpf_dynptr_kern *, dst, u32, offset, void *,
enum bpf_dynptr_type type;
int err;
- if (!dst->data || bpf_dynptr_is_rdonly(dst))
+ if (!dst->data || __bpf_dynptr_is_rdonly(dst))
return -EINVAL;
err = bpf_dynptr_check_off_len(dst, offset, len);
@@ -1592,7 +1592,7 @@ void *__bpf_dynptr_data(struct bpf_dynptr_kern *ptr, u32 offset, u32 len, bool w
if (err)
return 0;
- if (writable && bpf_dynptr_is_rdonly(ptr))
+ if (writable && __bpf_dynptr_is_rdonly(ptr))
return 0;
type = bpf_dynptr_get_type(ptr);
@@ -1705,6 +1705,33 @@ static const struct bpf_func_proto bpf_dynptr_trim_proto = {
.arg2_type = ARG_ANYTHING,
};
+BPF_CALL_1(bpf_dynptr_is_null, struct bpf_dynptr_kern *, ptr)
+{
+ return !ptr->data;
+}
+
+static const struct bpf_func_proto bpf_dynptr_is_null_proto = {
+ .func = bpf_dynptr_is_null,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_DYNPTR,
+};
+
+BPF_CALL_1(bpf_dynptr_is_rdonly, struct bpf_dynptr_kern *, ptr)
+{
+ if (!ptr->data)
+ return 0;
+
+ return __bpf_dynptr_is_rdonly(ptr);
+}
+
+static const struct bpf_func_proto bpf_dynptr_is_rdonly_proto = {
+ .func = bpf_dynptr_is_rdonly,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_DYNPTR,
+};
+
const struct bpf_func_proto bpf_get_current_task_proto __weak;
const struct bpf_func_proto bpf_get_current_task_btf_proto __weak;
const struct bpf_func_proto bpf_probe_read_user_proto __weak;
@@ -1781,6 +1808,10 @@ bpf_base_func_proto(enum bpf_func_id func_id)
return &bpf_dynptr_advance_proto;
case BPF_FUNC_dynptr_trim:
return &bpf_dynptr_trim_proto;
+ case BPF_FUNC_dynptr_is_null:
+ return &bpf_dynptr_is_null_proto;
+ case BPF_FUNC_dynptr_is_rdonly:
+ return &bpf_dynptr_is_rdonly_proto;
default:
break;
}
diff --git a/scripts/bpf_doc.py b/scripts/bpf_doc.py
index d5c389df6045..ecd227c2ea34 100755
--- a/scripts/bpf_doc.py
+++ b/scripts/bpf_doc.py
@@ -691,6 +691,7 @@ class PrinterHelpers(Printer):
'int',
'long',
'unsigned long',
+ 'bool',
'__be16',
'__be32',
@@ -761,6 +762,8 @@ class PrinterHelpers(Printer):
header = '''\
/* This is auto-generated file. See bpf_doc.py for details. */
+#include <stdbool.h>
+
/* Forward declarations of BPF structs */'''
print(header)
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 3b054553be30..90b6d0744df2 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -5467,6 +5467,24 @@ union bpf_attr {
* Return
* 0 on success, -EINVAL if the dynptr is invalid, -ERANGE if
* trying to trim more bytes than the size of the dynptr.
+ *
+ * bool bpf_dynptr_is_null(struct bpf_dynptr *ptr)
+ * Description
+ * Determine whether a dynptr is null / invalid.
+ *
+ * *ptr* must be an initialized dynptr.
+ * Return
+ * True if the dynptr is null, else false.
+ *
+ * bool bpf_dynptr_is_rdonly(struct bpf_dynptr *ptr)
+ * Description
+ * Determine whether a dynptr is read-only.
+ *
+ * *ptr* must be an initialized dynptr. If *ptr*
+ * is a null dynptr, this will return false.
+ * Return
+ * True if the dynptr is read-only and a valid dynptr,
+ * else false.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -5683,6 +5701,8 @@ union bpf_attr {
FN(dynptr_data_rdonly), \
FN(dynptr_advance), \
FN(dynptr_trim), \
+ FN(dynptr_is_null), \
+ FN(dynptr_is_rdonly), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
--
2.30.2
