Add negative test program and test for xdp datasize check (#3292)

Co-authored-by: Dhiren Vispute <Dhiren.Vispute@microsoft.com>

tests/end_to_end/netsh_test.cpp

@@ -14,6 +14,7 @@
 
 #include <winsock2.h>
 #include <windows.h>
+#include <iostream>
 #include <netsh.h>
 #include <regex>
 #include <sstream>
@@ -380,6 +381,57 @@ TEST_CASE("show verification droppacket_unsafe.o", "[netsh][verification]")
                   "\n");
 }
 
+TEST_CASE("show verification xdp_datasize_unsafe.o", "[netsh][verification]")
+{
+    _test_helper_netsh test_helper;
+    test_helper.initialize();
+
+    int result;
+    std::string output =
+        _run_netsh_command(handle_ebpf_show_verification, L"xdp_datasize_unsafe.o", L"xdp", nullptr, &result);
+    REQUIRE(result == ERROR_SUPPRESS_OUTPUT);
+    output = strip_paths(output);
+    REQUIRE(
+        output == "Verification failed\n"
+                  "\n"
+                  "Verification report:\n"
+                  "\n"
+                  "; ./tests/sample/unsafe/xdp_datasize_unsafe.c:32\n"
+                  ";     if (next_header + sizeof(ETHERNET_HEADER) > (char*)ctx->data_end) {\n"
+                  "4:  (r3.type in {number, ctx, stack, packet, shared})\n"
+                  "; ./tests/sample/unsafe/xdp_datasize_unsafe.c:32\n"
+                  ";     if (next_header + sizeof(ETHERNET_HEADER) > (char*)ctx->data_end) {\n"
+                  "5: Invalid type (valid_access(r3.offset) for comparison/subtraction)\n"
+                  "; ./tests/sample/unsafe/xdp_datasize_unsafe.c:32\n"
+                  ";     if (next_header + sizeof(ETHERNET_HEADER) > (char*)ctx->data_end) {\n"
+                  "5:  (r3.type == non_map_fd)\n"
+                  "; ./tests/sample/unsafe/xdp_datasize_unsafe.c:32\n"
+                  ";     if (next_header + sizeof(ETHERNET_HEADER) > (char*)ctx->data_end) {\n"
+                  "5: Cannot subtract pointers to different regions (r3.type == r1.type in {ctx, stack, packet})\n"
+                  "; ./tests/sample/unsafe/xdp_datasize_unsafe.c:38\n"
+                  ";     if (ethernet_header->Type != ntohs(ETHERNET_TYPE_IPV4) && ethernet_header->Type != "
+                  "ntohs(ETHERNET_TYPE_IPV6)) {\n"
+                  "6:  (r2.type in {ctx, stack, packet, shared})\n"
+                  "; ./tests/sample/unsafe/xdp_datasize_unsafe.c:38\n"
+                  ";     if (ethernet_header->Type != ntohs(ETHERNET_TYPE_IPV4) && ethernet_header->Type != "
+                  "ntohs(ETHERNET_TYPE_IPV6)) {\n"
+                  "6: Invalid type (valid_access(r2.offset+12, width=2) for read)\n"
+                  "; ./tests/sample/unsafe/xdp_datasize_unsafe.c:38\n"
+                  ";     if (ethernet_header->Type != ntohs(ETHERNET_TYPE_IPV4) && ethernet_header->Type != "
+                  "ntohs(ETHERNET_TYPE_IPV6)) {\n"
+                  "7:  (r1.type == number)\n"
+                  "; ./tests/sample/unsafe/xdp_datasize_unsafe.c:38\n"
+                  ";     if (ethernet_header->Type != ntohs(ETHERNET_TYPE_IPV4) && ethernet_header->Type != "
+                  "ntohs(ETHERNET_TYPE_IPV6)) {\n"
+                  "8:  (r1.type == number)\n"
+                  "; ./tests/sample/unsafe/xdp_datasize_unsafe.c:43\n"
+                  ";     return rc;\n"
+                  "10:  (r0.type == number)\n"
+                  "\n"
+                  "9 errors\n"
+                  "\n");
+}
+
 TEST_CASE("show verification printk_unsafe.o", "[netsh][verification]")
 {
     _test_helper_netsh test_helper;

tests/sample/unsafe/xdp_datasize_unsafe.c

@@ -0,0 +1,44 @@
+// Copyright (c) Microsoft Corporation
+// SPDX-License-Identifier: MIT
+
+// clang -O2 -Werror -c xdp_datasize_unsafe.c -o xdp_datasize_unsafe_jit.o
+//
+// For bpf code: clang -target bpf -O2 -Werror -c xdp_datsize_unsafe.c -o xdp_datasize_unsafe.o
+//
+
+#include "bpf_endian.h"
+#include "bpf_helpers.h"
+#include "net/if_ether.h"
+#include "net/ip.h"
+#include "net/udp.h"
+
+SEC("xdp")
+inline void*
+data_start(xdp_md_t* ctx)
+{
+    void* ptr;
+    asm volatile("%0 = *(u32 *)(%1 + %2)" : "=r"(ptr) : "r"(ctx), "i"(__builtin_offsetof(xdp_md_t, data)));
+    return ptr;
+}
+
+SEC("xdp")
+int
+unsafe_program(xdp_md_t* ctx)
+{
+    int rc = XDP_PASS;
+
+    ETHERNET_HEADER* ethernet_header = NULL;
+    char* next_header = data_start(ctx); // <== 64-bit truncated to 32-bit.
+    if (next_header + sizeof(ETHERNET_HEADER) > (char*)ctx->data_end) {
+        goto Done;
+    }
+
+    ethernet_header = (ETHERNET_HEADER*)next_header;
+    next_header = (char*)(ethernet_header + 1);
+    if (ethernet_header->Type != ntohs(ETHERNET_TYPE_IPV4) && ethernet_header->Type != ntohs(ETHERNET_TYPE_IPV6)) {
+        rc = XDP_DROP;
+    }
+
+Done:
+    return rc;
+}