1 files changed, 36 insertions, 0 deletions
diff --git a/test/syscalls/linux/proc_net.cc b/test/syscalls/linux/proc_net.cc
index 65bad06d4..897cf4950 100644
--- a/test/syscalls/linux/proc_net.cc
+++ b/test/syscalls/linux/proc_net.cc
@@ -326,6 +326,42 @@ TEST(ProcNetSnmp, UdpIn) {
   EXPECT_EQ(oldInDatagrams, newInDatagrams - 1);
 }
 
+TEST(ProcSysNetIpv4IpForward, Exists) {
+  auto fd =
+      ASSERT_NO_ERRNO_AND_VALUE(Open("/proc/sys/net/ipv4/ip_forward", O_RDWR));
+}
+
+TEST(ProcSysNetIpv4IpForward, DefaultValueEqZero) {
+  auto const fd =
+      ASSERT_NO_ERRNO_AND_VALUE(Open("/proc/sys/net/ipv4/ip_forward", O_RDWR));
+
+  char buf = 101;
+  EXPECT_THAT(PreadFd(fd.get(), &buf, sizeof(buf), 0),
+              SyscallSucceedsWithValue(sizeof(buf)));
+
+  EXPECT_TRUE(buf == '0') << "unexpected ip_forward: " << buf;
+}
+
+TEST(ProcSysNetIpv4IpForward, CanReadAndWrite) {
+  auto const fd =
+      ASSERT_NO_ERRNO_AND_VALUE(Open("/proc/sys/net/ipv4/ip_forward", O_RDWR));
+
+  char buf = 101;
+  EXPECT_THAT(PreadFd(fd.get(), &buf, sizeof(buf), 0),
+              SyscallSucceedsWithValue(sizeof(buf)));
+
+  EXPECT_TRUE(buf == '0') << "unexpected ip_forward: " << buf;
+
+  constexpr char to_write = '1';
+  EXPECT_THAT(PwriteFd(fd.get(), &to_write, sizeof(to_write), 0),
+              SyscallSucceedsWithValue(sizeof(to_write)));
+
+  buf = 101;
+  EXPECT_THAT(PreadFd(fd.get(), &buf, sizeof(buf), 0),
+              SyscallSucceedsWithValue(sizeof(buf)));
+  EXPECT_EQ(buf, to_write);
+}
+
 }  // namespace
 }  // namespace testing
 }  // namespace gvisor