[DFSan] Add custom wrapper for getsockopt.

The wrapper clears shadow for optval and optlen when written.

Reviewed By: stephan.yichao.zhao, vitalybuka

Differential Revision: https://reviews.llvm.org/D92961

compiler-rt/lib/dfsan/dfsan_custom.cpp

@@ -913,6 +913,20 @@ __dfsw_socketpair(int domain, int type, int protocol, int sv[2],
   return ret;
 }
 
+SANITIZER_INTERFACE_ATTRIBUTE int __dfsw_getsockopt(
+    int sockfd, int level, int optname, void *optval, socklen_t *optlen,
+    dfsan_label sockfd_label, dfsan_label level_label,
+    dfsan_label optname_label, dfsan_label optval_label,
+    dfsan_label optlen_label, dfsan_label *ret_label) {
+  int ret = getsockopt(sockfd, level, optname, optval, optlen);
+  if (ret != -1 && optval && optlen) {
+    dfsan_set_label(0, optlen, sizeof(*optlen));
+    dfsan_set_label(0, optval, *optlen);
+  }
+  *ret_label = 0;
+  return ret;
+}
+
 // Type of the trampoline function passed to the custom version of
 // dfsan_set_write_callback.
 typedef void (*write_trampoline_t)(

compiler-rt/lib/dfsan/done_abilist.txt

@@ -194,6 +194,7 @@ fun:get_current_dir_name=custom
 fun:gethostname=custom
 fun:getrlimit=custom
 fun:getrusage=custom
+fun:getsockopt=custom
 fun:nanosleep=custom
 fun:pread=custom
 fun:read=custom

compiler-rt/test/dfsan/custom.cpp

@@ -931,6 +931,27 @@ void test_socketpair() {
   ASSERT_READ_ZERO_LABEL(fd, sizeof(fd));
 }
 
+void test_getsockopt() {
+  int sockfd = socket(AF_UNIX, SOCK_DGRAM, 0);
+  assert(sockfd != -1);
+
+  int optval[2] = {-1, -1};
+  socklen_t optlen = sizeof(optval);
+  dfsan_set_label(i_label, &optval, sizeof(optval));
+  dfsan_set_label(i_label, &optlen, sizeof(optlen));
+  int ret = getsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &optval, &optlen);
+  assert(ret != -1);
+  assert(optlen == sizeof(int));
+  assert(optval[0] == 0);
+  assert(optval[1] == -1);
+  ASSERT_ZERO_LABEL(ret);
+  ASSERT_ZERO_LABEL(optlen);
+  ASSERT_ZERO_LABEL(optval[0]);
+  ASSERT_LABEL(optval[1], i_label);
+
+  close(sockfd);
+}
+
 void test_write() {
   int fd = open("/dev/null", O_WRONLY);
 
@@ -1113,6 +1134,7 @@ int main(void) {
   test_getpwuid_r();
   test_getrlimit();
   test_getrusage();
+  test_getsockopt();
   test_gettimeofday();
   test_inet_pton();
   test_localtime_r();