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Signed-off-by: Alan Jowett <[email protected]>

include/bpf/libbpf.h

@@ -915,6 +915,28 @@ void
 ring_buffer__free(struct ring_buffer* rb);
 /** @} */
 
+/**
+ * @brief Query the BPF program flags.
+ *ebpf_extension_data_v2_t
+ * @param[in] prog A pointer to the BPF program.
+ * @return The flags of the BPF program.
+ */
+uint32_t
+bpf_program__flags(const struct bpf_program* prog);
+
+/**
+ * @brief Set the BPF program flags.
+ *ebpf_extension_data_v2_t
+ * @param[in] prog A pointer to the BPF program.
+ * @param[in] flags The flags to set.
+ *ebpf_extension_data_v2_t
+ * @retval 0 The operation was successful.
+ * @retval <0 An error occured, and errno was set.
+ *ebpf_extension_data_v2_t
+ */
+int
+bpf_program__set_flags(struct bpf_program* prog, uint32_t flags);
+
 #else
 #pragma warning(push)
 #pragma warning(disable : 4200) // Zero-sized array in struct/union

include/ebpf_extension.h

@@ -91,21 +91,21 @@ typedef struct _ebpf_extension_program_dispatch_table
     ebpf_program_batch_end_invoke_function_t ebpf_program_batch_end_invoke_function;
 } ebpf_extension_program_dispatch_table_t;
 
-typedef struct _ebpf_extension_data_1
+typedef struct _ebpf_extension_data_v1
 {
     ebpf_extension_header_t header;
     const void* data;
-} ebpf_extension_data_t_1;
+} ebpf_extension_data_v1_t;
 
-typedef struct _ebpf_extension_data_2
+typedef struct _ebpf_extension_data_v2
 {
     ebpf_extension_header_t header;
     const void* data;
     size_t data_size;
     uint64_t flags;
-} ebpf_extension_data_t_2;
+} ebpf_extension_data_v2_t;
 
-typedef ebpf_extension_data_t_2 ebpf_extension_data_t;
+typedef ebpf_extension_data_v2_t ebpf_extension_data_t;
 
 typedef struct _ebpf_attach_provider_data
 {

include/ebpf_windows.h

@@ -70,15 +70,15 @@ typedef enum _ebpf_helper_function
 
 #define EBPF_MAX_GENERAL_HELPER_FUNCTION 0xFFFF
 
-// Warning: Version 1 of the eBPF extension data structures is being deprecated.
+// Warning: Version 1 of the eBPF extension data structures will be deprecated in a future release.
 // All extension data structures should be updated to version 2.
 // Leaving version 1 for backward compatibility for now.
 #define EBPF_ATTACH_CLIENT_DATA_VERSION_1 1
 #define EBPF_ATTACH_CLIENT_DATA_VERSION_2 2
 #define EBPF_ATTACH_CLIENT_DATA_CURRENT_VERSION 2
 
-#define EBPF_ATTACH_CLIENT_DATA_VERSION_1_SIZE EBPF_SIZE_INCLUDING_FIELD(ebpf_extension_data_t_1, data)
-#define EBPF_ATTACH_CLIENT_DATA_VERSION_1_TOTAL_SIZE sizeof(ebpf_extension_data_t_1)
+#define EBPF_ATTACH_CLIENT_DATA_VERSION_1_SIZE EBPF_SIZE_INCLUDING_FIELD(ebpf_extension_data_v1_t, data)
+#define EBPF_ATTACH_CLIENT_DATA_VERSION_1_TOTAL_SIZE sizeof(ebpf_extension_data_v1_t)
 #define EBPF_ATTACH_CLIENT_DATA_HEADER_VERSION_1                                   \
     {                                                                              \
         EBPF_ATTACH_CLIENT_DATA_VERSION_1, EBPF_ATTACH_CLIENT_DATA_VERSION_1_SIZE, \

libs/execution_context/ebpf_link.c

@@ -42,8 +42,12 @@ typedef struct _ebpf_link
     _Guarded_by_(lock) bpf_attach_type_t bpf_attach_type;
     _Guarded_by_(lock) enum bpf_link_type link_type;
     _Guarded_by_(lock) ebpf_program_type_t program_type;
-    _Guarded_by_(lock) ebpf_extension_data_t_1 client_data_v1;
-    _Guarded_by_(lock) ebpf_extension_data_t client_data_v2;
+    // Note: The new v2 data structure is uses to store either the v1 or the v2 data.
+    // The biggest difference is that the v2 data structure has a flags field and uses the header.size field
+    // to represent the size of ebpf_extension_data_t rather than the size of the data being pointed to.
+    // The v2 structure passes the size of the structure via the header.size field and the size of the data
+    // being pointed to via the data_size field.
+    _Guarded_by_(lock) ebpf_extension_data_v2_t client_data;
     _Guarded_by_(lock) NPI_CLIENT_CHARACTERISTICS client_characteristics;
     _Guarded_by_(lock) HANDLE nmr_client_handle;
     _Guarded_by_(lock) bool provider_attached;
@@ -221,7 +225,7 @@ static void
 _ebpf_link_free(_Frees_ptr_ ebpf_core_object_t* object)
 {
     ebpf_link_t* link = (ebpf_link_t*)object;
-    ebpf_free((void*)link->client_data_v1.data);
+    ebpf_free((void*)link->client_data.data);
     ebpf_lock_destroy(&link->lock);
     ebpf_epoch_free(link);
 }
@@ -254,27 +258,18 @@ ebpf_link_create(
     ebpf_lock_state_t state = ebpf_lock_lock(&local_link->lock);
     lock_held = true;
 
-    local_link->client_data_v1.header.version = EBPF_ATTACH_CLIENT_DATA_VERSION_1;
-    local_link->client_data_v1.header.size = context_data_length;
+    local_link->client_data.header.version = EBPF_ATTACH_CLIENT_DATA_VERSION_1;
+    local_link->client_data.header.size = context_data_length;
 
     if (context_data_length > 0) {
-        local_link->client_data_v1.data = ebpf_allocate_with_tag(context_data_length, EBPF_POOL_TAG_LINK);
-        if (!local_link->client_data_v1.data) {
+        local_link->client_data.data = ebpf_allocate_with_tag(context_data_length, EBPF_POOL_TAG_LINK);
+        if (!local_link->client_data.data) {
             retval = EBPF_NO_MEMORY;
             goto Exit;
         }
-        memcpy((void*)local_link->client_data_v1.data, context_data, context_data_length);
+        memcpy((void*)local_link->client_data.data, context_data, context_data_length);
     }
 
-    ebpf_extension_data_t client_attach_data = {
-        .header = EBPF_ATTACH_CLIENT_DATA_HEADER_VERSION_2,
-        .data = local_link->client_data_v1.data,
-        .data_size = context_data_length,
-        .flags = 0,
-    };
-
-    local_link->client_data_v2 = client_attach_data;
-
     local_link->module_id.Guid = module_id;
     local_link->module_id.Type = MIT_GUID;
     local_link->module_id.Length = sizeof(local_link->module_id);
@@ -335,16 +330,25 @@ ebpf_link_attach_program(_Inout_ ebpf_link_t* link, _Inout_ ebpf_program_t* prog
 
     ebpf_assert(link->program == NULL);
 
-    link->client_data_v2.flags = ebpf_program_get_flags(program);
-    // If any of the flags are set, use the V2 data structure.
-    if (link->client_data_v2.flags != 0) {
-        link->client_characteristics.ClientRegistrationInstance.NpiSpecificCharacteristics = &link->client_data_v2;
-    }
-    // If no flags are set, use the V1 data structure.
-    else {
-        link->client_characteristics.ClientRegistrationInstance.NpiSpecificCharacteristics = &link->client_data_v1;
+    uint64_t program_flags = ebpf_program_get_flags(program);
+
+    // If any of the flags are set, convert to the V2 data structure.
+    if (program_flags != 0) {
+        // Save values from the V1 data structure.
+        size_t data_size = link->client_data.header.size;
+        const void* data = link->client_data.data;
+
+        // Rewrite the V1 data structure with the V2 data structure.
+        link->client_data.header.version = EBPF_ATTACH_CLIENT_DATA_VERSION_2;
+        link->client_data.header.size = EBPF_ATTACH_CLIENT_DATA_VERSION_2_SIZE;
+        link->client_data.header.total_size = EBPF_ATTACH_CLIENT_DATA_VERSION_2_TOTAL_SIZE;
+        link->client_data.flags = program_flags;
+        link->client_data.data = data;
+        link->client_data.data_size = data_size;
     }
 
+    link->client_characteristics.ClientRegistrationInstance.NpiSpecificCharacteristics = &link->client_data;
+
     link->program = program;
     link->program_type = ebpf_program_type_uuid(link->program);
 
@@ -458,13 +462,11 @@ ebpf_link_detach_program(_Inout_ ebpf_link_t* link)
 
     ebpf_program_detach_link(link->program, link);
 
-    ebpf_free((void*)link->client_data_v1.data);
-
-    link->client_data_v1.data = NULL;
-    link->client_data_v1.header.size = 0;
+    link->client_data.data = NULL;
+    link->client_data.header.size = 0;
+    link->client_data.header.version = EBPF_ATTACH_CLIENT_DATA_VERSION_1;
+    link->client_data.data_size = 0;
     link->program = NULL;
-    link->client_data_v2.data = NULL;
-    link->client_data_v2.data_size = 0;
 
 Done:
     if (lock_held) {
@@ -573,8 +575,8 @@ ebpf_link_get_info(
 
     // Copy any additional parameters.
     size_t size = sizeof(struct bpf_link_info) - FIELD_OFFSET(struct bpf_link_info, attach_data);
-    if ((link->client_data_v1.header.size > 0) && (link->client_data_v1.header.size <= size)) {
-        memcpy(&info->attach_data, link->client_data_v1.data, link->client_data_v1.header.size);
+    if ((link->client_data.header.size > 0) && (link->client_data.header.size <= size)) {
+        memcpy(&info->attach_data, link->client_data.data, link->client_data.header.size);
     }
 
     ebpf_lock_unlock((ebpf_lock_t*)&link->lock, state);