bpf: widen dynptr size/offset to 64 bit

Dynptr currently caps size and offset at 24 bits, which isn’t sufficient
for file-backed use cases; even 32 bits can be limiting. Refactor dynptr
helpers/kfuncs to use 64-bit size and offset, ensuring consistency
across the APIs.

This change does not affect internals of xdp, skb or other dynptrs,
which continue to behave as before. Also it does not break binary
compatibility.

The widening enables large-file access support via dynptr, implemented
in the next patches.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20251026203853.135105-3-mykyta.yatsenko5@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

3 files changed, 16 insertions, 16 deletions

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 6829936d33f5..77edd0253989 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -5618,7 +5618,7 @@ union bpf_attr {
  *	Return
  *		*sk* if casting is valid, or **NULL** otherwise.
  *
- * long bpf_dynptr_from_mem(void *data, u32 size, u64 flags, struct bpf_dynptr *ptr)
+ * long bpf_dynptr_from_mem(void *data, u64 size, u64 flags, struct bpf_dynptr *ptr)
  *	Description
  *		Get a dynptr to local memory *data*.
  *
@@ -5661,7 +5661,7 @@ union bpf_attr {
  *	Return
  *		Nothing. Always succeeds.
  *
- * long bpf_dynptr_read(void *dst, u32 len, const struct bpf_dynptr *src, u32 offset, u64 flags)
+ * long bpf_dynptr_read(void *dst, u64 len, const struct bpf_dynptr *src, u64 offset, u64 flags)
  *	Description
  *		Read *len* bytes from *src* into *dst*, starting from *offset*
  *		into *src*.
@@ -5671,7 +5671,7 @@ union bpf_attr {
  *		of *src*'s data, -EINVAL if *src* is an invalid dynptr or if
  *		*flags* is not 0.
  *
- * long bpf_dynptr_write(const struct bpf_dynptr *dst, u32 offset, void *src, u32 len, u64 flags)
+ * long bpf_dynptr_write(const struct bpf_dynptr *dst, u64 offset, void *src, u64 len, u64 flags)
  *	Description
  *		Write *len* bytes from *src* into *dst*, starting from *offset*
  *		into *dst*.
@@ -5692,7 +5692,7 @@ union bpf_attr {
  *		is a read-only dynptr or if *flags* is not correct. For skb-type dynptrs,
  *		other errors correspond to errors returned by **bpf_skb_store_bytes**\ ().
  *
- * void *bpf_dynptr_data(const struct bpf_dynptr *ptr, u32 offset, u32 len)
+ * void *bpf_dynptr_data(const struct bpf_dynptr *ptr, u64 offset, u64 len)
  *	Description
  *		Get a pointer to the underlying dynptr data.
  *
diff --git a/tools/testing/selftests/bpf/bpf_kfuncs.h b/tools/testing/selftests/bpf/bpf_kfuncs.h
index 794d44d19c88..e0189254bb6e 100644
--- a/tools/testing/selftests/bpf/bpf_kfuncs.h
+++ b/tools/testing/selftests/bpf/bpf_kfuncs.h
@@ -28,8 +28,8 @@ extern int bpf_dynptr_from_skb_meta(struct __sk_buff *skb, __u64 flags,
  *  Either a direct pointer to the dynptr data or a pointer to the user-provided
  *  buffer if unable to obtain a direct pointer
  */
-extern void *bpf_dynptr_slice(const struct bpf_dynptr *ptr, __u32 offset,
-			      void *buffer, __u32 buffer__szk) __ksym __weak;
+extern void *bpf_dynptr_slice(const struct bpf_dynptr *ptr, __u64 offset,
+			      void *buffer, __u64 buffer__szk) __ksym __weak;
 
 /* Description
  *  Obtain a read-write pointer to the dynptr's data
@@ -37,13 +37,13 @@ extern void *bpf_dynptr_slice(const struct bpf_dynptr *ptr, __u32 offset,
  *  Either a direct pointer to the dynptr data or a pointer to the user-provided
  *  buffer if unable to obtain a direct pointer
  */
-extern void *bpf_dynptr_slice_rdwr(const struct bpf_dynptr *ptr, __u32 offset,
-			      void *buffer, __u32 buffer__szk) __ksym __weak;
+extern void *bpf_dynptr_slice_rdwr(const struct bpf_dynptr *ptr, __u64 offset, void *buffer,
+				   __u64 buffer__szk) __ksym __weak;
 
-extern int bpf_dynptr_adjust(const struct bpf_dynptr *ptr, __u32 start, __u32 end) __ksym __weak;
+extern int bpf_dynptr_adjust(const struct bpf_dynptr *ptr, __u64 start, __u64 end) __ksym __weak;
 extern bool bpf_dynptr_is_null(const struct bpf_dynptr *ptr) __ksym __weak;
 extern bool bpf_dynptr_is_rdonly(const struct bpf_dynptr *ptr) __ksym __weak;
-extern __u32 bpf_dynptr_size(const struct bpf_dynptr *ptr) __ksym __weak;
+extern __u64 bpf_dynptr_size(const struct bpf_dynptr *ptr) __ksym __weak;
 extern int bpf_dynptr_clone(const struct bpf_dynptr *ptr, struct bpf_dynptr *clone__init) __ksym __weak;
 
 /* Description
diff --git a/tools/testing/selftests/bpf/progs/dynptr_success.c b/tools/testing/selftests/bpf/progs/dynptr_success.c
index 127dea342e5a..e0d672d93adf 100644
--- a/tools/testing/selftests/bpf/progs/dynptr_success.c
+++ b/tools/testing/selftests/bpf/progs/dynptr_success.c
@@ -914,8 +914,8 @@ void *user_ptr;
 char expected_str[384];
 __u32 test_len[7] = {0/* placeholder */, 0, 1, 2, 255, 256, 257};
 
-typedef int (*bpf_read_dynptr_fn_t)(struct bpf_dynptr *dptr, u32 off,
-				    u32 size, const void *unsafe_ptr);
+typedef int (*bpf_read_dynptr_fn_t)(struct bpf_dynptr *dptr, u64 off,
+				    u64 size, const void *unsafe_ptr);
 
 /* Returns the offset just before the end of the maximum sized xdp fragment.
  * Any write larger than 32 bytes will be split between 2 fragments.
@@ -1106,16 +1106,16 @@ int test_copy_from_user_str_dynptr(void *ctx)
 	return 0;
 }
 
-static int bpf_copy_data_from_user_task(struct bpf_dynptr *dptr, u32 off,
-					u32 size, const void *unsafe_ptr)
+static int bpf_copy_data_from_user_task(struct bpf_dynptr *dptr, u64 off,
+					u64 size, const void *unsafe_ptr)
 {
 	struct task_struct *task = bpf_get_current_task_btf();
 
 	return bpf_copy_from_user_task_dynptr(dptr, off, size, unsafe_ptr, task);
 }
 
-static int bpf_copy_data_from_user_task_str(struct bpf_dynptr *dptr, u32 off,
-					    u32 size, const void *unsafe_ptr)
+static int bpf_copy_data_from_user_task_str(struct bpf_dynptr *dptr, u64 off,
+					    u64 size, const void *unsafe_ptr)
 {
 	struct task_struct *task = bpf_get_current_task_btf();