ip6tables: test initial state

Tests that we have the correct initial (empty) state for ip6tables.

#3549

PiperOrigin-RevId: 327477657

test/syscalls/BUILD

@@ -250,6 +250,10 @@ syscall_test(
     test = "//test/syscalls/linux:iptables_test",
 )
 
+syscall_test(
+    test = "//test/syscalls/linux:ip6tables_test",
+)
+
 syscall_test(
     size = "large",
     shard_count = 5,

test/syscalls/linux/BUILD

@@ -1029,6 +1029,24 @@ cc_binary(
     ],
 )
 
+cc_binary(
+    name = "ip6tables_test",
+    testonly = 1,
+    srcs = [
+        "ip6tables.cc",
+    ],
+    linkstatic = 1,
+    deps = [
+        ":iptables_types",
+        ":socket_test_util",
+        "//test/util:capability_util",
+        "//test/util:file_descriptor",
+        gtest,
+        "//test/util:test_main",
+        "//test/util:test_util",
+    ],
+)
+
 cc_binary(
     name = "itimer_test",
     testonly = 1,

test/syscalls/linux/ip6tables.cc

@@ -0,0 +1,163 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <linux/capability.h>
+#include <sys/socket.h>
+
+#include "gtest/gtest.h"
+#include "test/syscalls/linux/iptables.h"
+#include "test/syscalls/linux/socket_test_util.h"
+#include "test/util/capability_util.h"
+#include "test/util/file_descriptor.h"
+#include "test/util/test_util.h"
+
+namespace gvisor {
+namespace testing {
+
+namespace {
+
+constexpr char kNatTablename[] = "nat";
+constexpr char kErrorTarget[] = "ERROR";
+constexpr size_t kEmptyStandardEntrySize =
+    sizeof(struct ip6t_entry) + sizeof(struct xt_standard_target);
+constexpr size_t kEmptyErrorEntrySize =
+    sizeof(struct ip6t_entry) + sizeof(struct xt_error_target);
+
+// This tests the initial state of a machine with empty ip6tables via
+// getsockopt(IP6T_SO_GET_INFO). We don't have a guarantee that the iptables are
+// empty when running in native, but we can test that gVisor has the same
+// initial state that a newly-booted Linux machine would have.
+TEST(IP6TablesTest, InitialInfo) {
+  // TODO(gvisor.dev/issue/3549): Enable for ip6tables.
+  SKIP_IF(true);
+  SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_RAW)));
+
+  FileDescriptor sock =
+      ASSERT_NO_ERRNO_AND_VALUE(Socket(AF_INET6, SOCK_RAW, IPPROTO_RAW));
+
+  // Get info via sockopt.
+  struct ipt_getinfo info = {};
+  snprintf(info.name, XT_TABLE_MAXNAMELEN, "%s", kNatTablename);
+  socklen_t info_size = sizeof(info);
+  ASSERT_THAT(
+      getsockopt(sock.get(), SOL_IPV6, IP6T_SO_GET_INFO, &info, &info_size),
+      SyscallSucceeds());
+
+  // The nat table supports PREROUTING, and OUTPUT.
+  unsigned int valid_hooks =
+      (1 << NF_IP6_PRE_ROUTING) | (1 << NF_IP6_LOCAL_OUT) |
+      (1 << NF_IP6_POST_ROUTING) | (1 << NF_IP6_LOCAL_IN);
+  EXPECT_EQ(info.valid_hooks, valid_hooks);
+
+  // Each chain consists of an empty entry with a standard target..
+  EXPECT_EQ(info.hook_entry[NF_IP6_PRE_ROUTING], 0);
+  EXPECT_EQ(info.hook_entry[NF_IP6_LOCAL_IN], kEmptyStandardEntrySize);
+  EXPECT_EQ(info.hook_entry[NF_IP6_LOCAL_OUT], kEmptyStandardEntrySize * 2);
+  EXPECT_EQ(info.hook_entry[NF_IP6_POST_ROUTING], kEmptyStandardEntrySize * 3);
+
+  // The underflow points are the same as the entry points.
+  EXPECT_EQ(info.underflow[NF_IP6_PRE_ROUTING], 0);
+  EXPECT_EQ(info.underflow[NF_IP6_LOCAL_IN], kEmptyStandardEntrySize);
+  EXPECT_EQ(info.underflow[NF_IP6_LOCAL_OUT], kEmptyStandardEntrySize * 2);
+  EXPECT_EQ(info.underflow[NF_IP6_POST_ROUTING], kEmptyStandardEntrySize * 3);
+
+  // One entry for each chain, plus an error entry at the end.
+  EXPECT_EQ(info.num_entries, 5);
+
+  EXPECT_EQ(info.size, 4 * kEmptyStandardEntrySize + kEmptyErrorEntrySize);
+  EXPECT_EQ(strcmp(info.name, kNatTablename), 0);
+}
+
+// This tests the initial state of a machine with empty ip6tables via
+// getsockopt(IP6T_SO_GET_ENTRIES). We don't have a guarantee that the iptables
+// are empty when running in native, but we can test that gVisor has the same
+// initial state that a newly-booted Linux machine would have.
+TEST(IP6TablesTest, InitialEntries) {
+  // TODO(gvisor.dev/issue/3549): Enable for ip6tables.
+  SKIP_IF(true);
+  SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_RAW)));
+
+  FileDescriptor sock =
+      ASSERT_NO_ERRNO_AND_VALUE(Socket(AF_INET6, SOCK_RAW, IPPROTO_RAW));
+
+  // Get info via sockopt.
+  struct ipt_getinfo info = {};
+  snprintf(info.name, XT_TABLE_MAXNAMELEN, "%s", kNatTablename);
+  socklen_t info_size = sizeof(info);
+  ASSERT_THAT(
+      getsockopt(sock.get(), SOL_IPV6, IP6T_SO_GET_INFO, &info, &info_size),
+      SyscallSucceeds());
+
+  // Use info to get entries.
+  socklen_t entries_size = sizeof(struct ip6t_get_entries) + info.size;
+  struct ip6t_get_entries* entries =
+      static_cast<struct ip6t_get_entries*>(malloc(entries_size));
+  snprintf(entries->name, XT_TABLE_MAXNAMELEN, "%s", kNatTablename);
+  entries->size = info.size;
+  ASSERT_THAT(getsockopt(sock.get(), SOL_IPV6, IP6T_SO_GET_ENTRIES, entries,
+                         &entries_size),
+              SyscallSucceeds());
+
+  // Verify the name and size.
+  ASSERT_EQ(info.size, entries->size);
+  ASSERT_EQ(strcmp(entries->name, kNatTablename), 0);
+
+  // Verify that the entrytable is 4 entries with accept targets and no matches
+  // followed by a single error target.
+  size_t entry_offset = 0;
+  while (entry_offset < entries->size) {
+    struct ip6t_entry* entry = reinterpret_cast<struct ip6t_entry*>(
+        reinterpret_cast<char*>(entries->entrytable) + entry_offset);
+
+    // ipv6 should be zeroed.
+    struct ip6t_ip6 zeroed = {};
+    ASSERT_EQ(memcmp(static_cast<void*>(&zeroed),
+                     static_cast<void*>(&entry->ipv6), sizeof(zeroed)),
+              0);
+
+    // target_offset should be zero.
+    EXPECT_EQ(entry->target_offset, sizeof(ip6t_entry));
+
+    if (entry_offset < kEmptyStandardEntrySize * 4) {
+      // The first 4 entries are standard targets
+      struct xt_standard_target* target =
+          reinterpret_cast<struct xt_standard_target*>(entry->elems);
+      EXPECT_EQ(entry->next_offset, kEmptyStandardEntrySize);
+      EXPECT_EQ(target->target.u.user.target_size, sizeof(*target));
+      EXPECT_EQ(strcmp(target->target.u.user.name, ""), 0);
+      EXPECT_EQ(target->target.u.user.revision, 0);
+      // This is what's returned for an accept verdict. I don't know why.
+      EXPECT_EQ(target->verdict, -NF_ACCEPT - 1);
+    } else {
+      // The last entry is an error target
+      struct xt_error_target* target =
+          reinterpret_cast<struct xt_error_target*>(entry->elems);
+      EXPECT_EQ(entry->next_offset, kEmptyErrorEntrySize);
+      EXPECT_EQ(target->target.u.user.target_size, sizeof(*target));
+      EXPECT_EQ(strcmp(target->target.u.user.name, kErrorTarget), 0);
+      EXPECT_EQ(target->target.u.user.revision, 0);
+      EXPECT_EQ(strcmp(target->errorname, kErrorTarget), 0);
+    }
+
+    entry_offset += entry->next_offset;
+    break;
+  }
+
+  free(entries);
+}
+
+}  // namespace
+
+}  // namespace testing
+}  // namespace gvisor

test/syscalls/linux/iptables.cc

@@ -67,7 +67,7 @@ TEST(IPTablesBasic, FailSockoptNonRaw) {
   struct ipt_getinfo info = {};
   snprintf(info.name, XT_TABLE_MAXNAMELEN, "%s", kNatTablename);
   socklen_t info_size = sizeof(info);
-  EXPECT_THAT(getsockopt(sock, IPPROTO_IP, SO_GET_INFO, &info, &info_size),
+  EXPECT_THAT(getsockopt(sock, IPPROTO_IP, IPT_SO_GET_INFO, &info, &info_size),
               SyscallFailsWithErrno(ENOPROTOOPT));
 
   ASSERT_THAT(close(sock), SyscallSucceeds());
@@ -112,7 +112,7 @@ TEST_F(IPTablesTest, InitialState) {
   struct ipt_getinfo info = {};
   snprintf(info.name, XT_TABLE_MAXNAMELEN, "%s", kNatTablename);
   socklen_t info_size = sizeof(info);
-  ASSERT_THAT(getsockopt(s_, IPPROTO_IP, SO_GET_INFO, &info, &info_size),
+  ASSERT_THAT(getsockopt(s_, IPPROTO_IP, IPT_SO_GET_INFO, &info, &info_size),
               SyscallSucceeds());
 
   // The nat table supports PREROUTING, and OUTPUT.
@@ -148,7 +148,7 @@ TEST_F(IPTablesTest, InitialState) {
   snprintf(entries->name, XT_TABLE_MAXNAMELEN, "%s", kNatTablename);
   entries->size = info.size;
   ASSERT_THAT(
-      getsockopt(s_, IPPROTO_IP, SO_GET_ENTRIES, entries, &entries_size),
+      getsockopt(s_, IPPROTO_IP, IPT_SO_GET_ENTRIES, entries, &entries_size),
       SyscallSucceeds());
 
   // Verify the name and size.

test/syscalls/linux/iptables.h

@@ -27,27 +27,32 @@
 
 #include <linux/netfilter/x_tables.h>
 #include <linux/netfilter_ipv4.h>
+#include <linux/netfilter_ipv6.h>
 #include <net/if.h>
 #include <netinet/ip.h>
 #include <stdint.h>
 
+//
+// IPv4 ABI.
+//
+
 #define ipt_standard_target xt_standard_target
 #define ipt_entry_target xt_entry_target
 #define ipt_error_target xt_error_target
 
 enum SockOpts {
   // For setsockopt.
-  BASE_CTL = 64,
-  SO_SET_REPLACE = BASE_CTL,
-  SO_SET_ADD_COUNTERS,
-  SO_SET_MAX = SO_SET_ADD_COUNTERS,
+  IPT_BASE_CTL = 64,
+  IPT_SO_SET_REPLACE = IPT_BASE_CTL,
+  IPT_SO_SET_ADD_COUNTERS = IPT_BASE_CTL + 1,
+  IPT_SO_SET_MAX = IPT_SO_SET_ADD_COUNTERS,
 
   // For getsockopt.
-  SO_GET_INFO = BASE_CTL,
-  SO_GET_ENTRIES,
-  SO_GET_REVISION_MATCH,
-  SO_GET_REVISION_TARGET,
-  SO_GET_MAX = SO_GET_REVISION_TARGET
+  IPT_SO_GET_INFO = IPT_BASE_CTL,
+  IPT_SO_GET_ENTRIES = IPT_BASE_CTL + 1,
+  IPT_SO_GET_REVISION_MATCH = IPT_BASE_CTL + 2,
+  IPT_SO_GET_REVISION_TARGET = IPT_BASE_CTL + 3,
+  IPT_SO_GET_MAX = IPT_SO_GET_REVISION_TARGET
 };
 
 // ipt_ip specifies basic matching criteria that can be applied by examining
@@ -115,7 +120,7 @@ struct ipt_entry {
   unsigned char elems[0];
 };
 
-// Passed to getsockopt(SO_GET_INFO).
+// Passed to getsockopt(IPT_SO_GET_INFO).
 struct ipt_getinfo {
   // The name of the table. The user only fills this in, the rest is filled in
   // when returning from getsockopt. Currently "nat" and "mangle" are supported.
@@ -127,7 +132,7 @@ struct ipt_getinfo {
   unsigned int valid_hooks;
 
   // The offset into the entry table for each valid hook. The entry table is
-  // returned by getsockopt(SO_GET_ENTRIES).
+  // returned by getsockopt(IPT_SO_GET_ENTRIES).
   unsigned int hook_entry[NF_IP_NUMHOOKS];
 
   // For each valid hook, the underflow is the offset into the entry table to
@@ -142,14 +147,14 @@ struct ipt_getinfo {
   unsigned int underflow[NF_IP_NUMHOOKS];
 
   // The number of entries in the entry table returned by
-  // getsockopt(SO_GET_ENTRIES).
+  // getsockopt(IPT_SO_GET_ENTRIES).
   unsigned int num_entries;
 
-  // The size of the entry table returned by getsockopt(SO_GET_ENTRIES).
+  // The size of the entry table returned by getsockopt(IPT_SO_GET_ENTRIES).
   unsigned int size;
 };
 
-// Passed to getsockopt(SO_GET_ENTRIES).
+// Passed to getsockopt(IPT_SO_GET_ENTRIES).
 struct ipt_get_entries {
   // The name of the table. The user fills this in. Currently "nat" and "mangle"
   // are supported.
@@ -195,4 +200,103 @@ struct ipt_replace {
   struct ipt_entry entries[0];
 };
 
+//
+// IPv6 ABI.
+//
+
+enum SockOpts6 {
+  // For setsockopt.
+  IP6T_BASE_CTL = 64,
+  IP6T_SO_SET_REPLACE = IP6T_BASE_CTL,
+  IP6T_SO_SET_ADD_COUNTERS = IP6T_BASE_CTL + 1,
+  IP6T_SO_SET_MAX = IP6T_SO_SET_ADD_COUNTERS,
+
+  // For getsockopt.
+  IP6T_SO_GET_INFO = IP6T_BASE_CTL,
+  IP6T_SO_GET_ENTRIES = IP6T_BASE_CTL + 1,
+  IP6T_SO_GET_REVISION_MATCH = IP6T_BASE_CTL + 4,
+  IP6T_SO_GET_REVISION_TARGET = IP6T_BASE_CTL + 5,
+  IP6T_SO_GET_MAX = IP6T_SO_GET_REVISION_TARGET
+};
+
+// ip6t_ip6 specifies basic matching criteria that can be applied by examining
+// only the IP header of a packet.
+struct ip6t_ip6 {
+  // Source IP address.
+  struct in6_addr src;
+
+  // Destination IP address.
+  struct in6_addr dst;
+
+  // Source IP address mask.
+  struct in6_addr smsk;
+
+  // Destination IP address mask.
+  struct in6_addr dmsk;
+
+  // Input interface.
+  char iniface[IFNAMSIZ];
+
+  // Output interface.
+  char outiface[IFNAMSIZ];
+
+  // Input interface mask.
+  unsigned char iniface_mask[IFNAMSIZ];
+
+  // Output interface mask.
+  unsigned char outiface_mask[IFNAMSIZ];
+
+  // Transport protocol.
+  uint16_t proto;
+
+  // TOS.
+  uint8_t tos;
+
+  // Flags.
+  uint8_t flags;
+
+  // Inverse flags.
+  uint8_t invflags;
+};
+
+// ip6t_entry is an ip6tables rule.
+struct ip6t_entry {
+  // Basic matching information used to match a packet's IP header.
+  struct ip6t_ip6 ipv6;
+
+  // A caching field that isn't used by userspace.
+  unsigned int nfcache;
+
+  // The number of bytes between the start of this entry and the rule's target.
+  uint16_t target_offset;
+
+  // The total size of this rule, from the beginning of the entry to the end of
+  // the target.
+  uint16_t next_offset;
+
+  // A return pointer not used by userspace.
+  unsigned int comefrom;
+
+  // Counters for packets and bytes, which we don't yet implement.
+  struct xt_counters counters;
+
+  // The data for all this rules matches followed by the target. This runs
+  // beyond the value of sizeof(struct ip6t_entry).
+  unsigned char elems[0];
+};
+
+// Passed to getsockopt(IP6T_SO_GET_ENTRIES).
+struct ip6t_get_entries {
+  // The name of the table.
+  char name[XT_TABLE_MAXNAMELEN];
+
+  // The size of the entry table in bytes. The user fills this in with the value
+  // from struct ipt_getinfo.size.
+  unsigned int size;
+
+  // The entries for the given table. This will run past the size defined by
+  // sizeof(struct ip6t_get_entries).
+  struct ip6t_entry entrytable[0];
+};
+
 #endif  // GVISOR_TEST_SYSCALLS_IPTABLES_TYPES_H_