Add two new helper functions: bpf_dynptr_get_size and
bpf_dynptr_get_offset.
bpf_dynptr_get_size returns the number of usable bytes in a dynptr and
bpf_dynptr_get_offset returns the current offset into the dynptr.
Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx>
---
include/linux/bpf.h | 2 +-
include/uapi/linux/bpf.h | 25 +++++++++++++++++++++
kernel/bpf/helpers.c | 40 +++++++++++++++++++++++++++++++---
kernel/trace/bpf_trace.c | 4 ++--
tools/include/uapi/linux/bpf.h | 25 +++++++++++++++++++++
5 files changed, 90 insertions(+), 6 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 5628256de3e5..753444e1478c 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1118,7 +1118,7 @@ enum bpf_dynptr_type {
};
int bpf_dynptr_check_size(u32 size);
-u32 bpf_dynptr_get_size(struct bpf_dynptr_kern *ptr);
+u32 __bpf_dynptr_get_size(struct bpf_dynptr_kern *ptr);
#ifdef CONFIG_BPF_JIT
int bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 80582bc00bf4..5ad52d481cde 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5571,6 +5571,29 @@ union bpf_attr {
* Return
* True if the dynptr is read-only and a valid dynptr,
* else false.
+ *
+ * long bpf_dynptr_get_size(struct bpf_dynptr *ptr)
+ * Description
+ * Get the size of *ptr*.
+ *
+ * Size refers to the number of usable bytes. For example,
+ * if *ptr* was initialized with 100 bytes and its
+ * offset was advanced by 40 bytes, then the size will be
+ * 60 bytes.
+ *
+ * *ptr* must be an initialized dynptr.
+ * Return
+ * The size of the dynptr on success, -EINVAL if the dynptr is
+ * invalid.
+ *
+ * long bpf_dynptr_get_offset(struct bpf_dynptr *ptr)
+ * Description
+ * Get the offset of the dynptr.
+ *
+ * *ptr* must be an initialized dynptr.
+ * Return
+ * The offset of the dynptr on success, -EINVAL if the dynptr is
+ * invalid.
*/
#define ___BPF_FUNC_MAPPER(FN, ctx...) \
FN(unspec, 0, ##ctx) \
@@ -5791,6 +5814,8 @@ union bpf_attr {
FN(dynptr_trim, 215, ##ctx) \
FN(dynptr_is_null, 216, ##ctx) \
FN(dynptr_is_rdonly, 217, ##ctx) \
+ FN(dynptr_get_size, 218, ##ctx) \
+ FN(dynptr_get_offset, 219, ##ctx) \
/* */
/* backwards-compatibility macros for users of __BPF_FUNC_MAPPER that don't
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index cd9e1a2972fe..0164d7e4b5a6 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -1424,7 +1424,7 @@ static enum bpf_dynptr_type bpf_dynptr_get_type(const struct bpf_dynptr_kern *pt
return (ptr->size & ~(DYNPTR_RDONLY_BIT)) >> DYNPTR_TYPE_SHIFT;
}
-u32 bpf_dynptr_get_size(struct bpf_dynptr_kern *ptr)
+u32 __bpf_dynptr_get_size(struct bpf_dynptr_kern *ptr)
{
return ptr->size & DYNPTR_SIZE_MASK;
}
@@ -1457,7 +1457,7 @@ void bpf_dynptr_set_null(struct bpf_dynptr_kern *ptr)
static int bpf_dynptr_check_off_len(struct bpf_dynptr_kern *ptr, u32 offset, u32 len)
{
- u32 size = bpf_dynptr_get_size(ptr);
+ u32 size = __bpf_dynptr_get_size(ptr);
if (len > size || offset > size - len)
return -E2BIG;
@@ -1655,7 +1655,7 @@ static int bpf_dynptr_adjust(struct bpf_dynptr_kern *ptr, u32 off_inc, u32 sz_de
if (!ptr->data)
return -EINVAL;
- size = bpf_dynptr_get_size(ptr);
+ size = __bpf_dynptr_get_size(ptr);
if (sz_dec > size)
return -ERANGE;
@@ -1730,6 +1730,36 @@ static const struct bpf_func_proto bpf_dynptr_is_rdonly_proto = {
.arg1_type = ARG_PTR_TO_DYNPTR,
};
+BPF_CALL_1(bpf_dynptr_get_size, struct bpf_dynptr_kern *, ptr)
+{
+ if (!ptr->data)
+ return -EINVAL;
+
+ return __bpf_dynptr_get_size(ptr);
+}
+
+static const struct bpf_func_proto bpf_dynptr_get_size_proto = {
+ .func = bpf_dynptr_get_size,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_DYNPTR,
+};
+
+BPF_CALL_1(bpf_dynptr_get_offset, struct bpf_dynptr_kern *, ptr)
+{
+ if (!ptr->data)
+ return -EINVAL;
+
+ return ptr->offset;
+}
+
+static const struct bpf_func_proto bpf_dynptr_get_offset_proto = {
+ .func = bpf_dynptr_get_offset,
+ .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;
@@ -1842,6 +1872,10 @@ bpf_base_func_proto(enum bpf_func_id func_id)
return &bpf_dynptr_is_null_proto;
case BPF_FUNC_dynptr_is_rdonly:
return &bpf_dynptr_is_rdonly_proto;
+ case BPF_FUNC_dynptr_get_size:
+ return &bpf_dynptr_get_size_proto;
+ case BPF_FUNC_dynptr_get_offset:
+ return &bpf_dynptr_get_offset_proto;
#ifdef CONFIG_CGROUPS
case BPF_FUNC_cgrp_storage_get:
return &bpf_cgrp_storage_get_proto;
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 3bbd3f0c810c..e057570b4e2c 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1349,9 +1349,9 @@ int bpf_verify_pkcs7_signature(struct bpf_dynptr_kern *data_ptr,
}
return verify_pkcs7_signature(data_ptr->data,
- bpf_dynptr_get_size(data_ptr),
+ __bpf_dynptr_get_size(data_ptr),
sig_ptr->data,
- bpf_dynptr_get_size(sig_ptr),
+ __bpf_dynptr_get_size(sig_ptr),
trusted_keyring->key,
VERIFYING_UNSPECIFIED_SIGNATURE, NULL,
NULL);
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 80582bc00bf4..5ad52d481cde 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -5571,6 +5571,29 @@ union bpf_attr {
* Return
* True if the dynptr is read-only and a valid dynptr,
* else false.
+ *
+ * long bpf_dynptr_get_size(struct bpf_dynptr *ptr)
+ * Description
+ * Get the size of *ptr*.
+ *
+ * Size refers to the number of usable bytes. For example,
+ * if *ptr* was initialized with 100 bytes and its
+ * offset was advanced by 40 bytes, then the size will be
+ * 60 bytes.
+ *
+ * *ptr* must be an initialized dynptr.
+ * Return
+ * The size of the dynptr on success, -EINVAL if the dynptr is
+ * invalid.
+ *
+ * long bpf_dynptr_get_offset(struct bpf_dynptr *ptr)
+ * Description
+ * Get the offset of the dynptr.
+ *
+ * *ptr* must be an initialized dynptr.
+ * Return
+ * The offset of the dynptr on success, -EINVAL if the dynptr is
+ * invalid.
*/
#define ___BPF_FUNC_MAPPER(FN, ctx...) \
FN(unspec, 0, ##ctx) \
@@ -5791,6 +5814,8 @@ union bpf_attr {
FN(dynptr_trim, 215, ##ctx) \
FN(dynptr_is_null, 216, ##ctx) \
FN(dynptr_is_rdonly, 217, ##ctx) \
+ FN(dynptr_get_size, 218, ##ctx) \
+ FN(dynptr_get_offset, 219, ##ctx) \
/* */
/* backwards-compatibility macros for users of __BPF_FUNC_MAPPER that don't
--
2.30.2
