[DFSan] Add custom wrapper for recvmmsg.

[morehouse]

Summary

Uses the recvmsg wrapper logic in a loop.

[stephan.yichao.zhao]

compiler-rt/test/dfsan/custom.cpp

376

Is it possible to confirm that timeout spec is not zero-out?

[morehouse]

• Test that timeout's shadow is not cleared.

compiler-rt/lib/dfsan/dfsan_custom.cpp

SANITIZER_INTERFACE_ATTRIBUTE int __dfsw_nanosleep(const struct timespec *req,
   *ret_label = 0;
   if (ret == -1) {
     // Interrupted by a signal, rem is filled with the remaining time.
     dfsan_set_label(0, rem, sizeof(struct timespec));
   }
   return ret;
 }
 
-SANITIZER_INTERFACE_ATTRIBUTE ssize_t __dfsw_recvmsg(
-    int sockfd, struct msghdr *msg, int flags, dfsan_label sockfd_label,
-    dfsan_label msg_label, dfsan_label flags_label, dfsan_label *ret_label) {
-  ssize_t ret = recvmsg(sockfd, msg, flags);
-  if (ret >= 0) {
-    dfsan_set_label(0, msg, sizeof(*msg));
-    dfsan_set_label(0, msg->msg_name, msg->msg_namelen);
-    dfsan_set_label(0, msg->msg_control, msg->msg_controllen);
-    for (size_t remaining = ret, i = 0; remaining > 0; ++i) {
-      assert(i < msg->msg_iovlen);
-      struct iovec *iov = &msg->msg_iov[i];
-      size_t written = remaining < iov->iov_len ? remaining : iov->iov_len;
-      dfsan_set_label(0, iov->iov_base, written);
-      remaining -= written;
-    }
-  }
+static void clear_msghdr_labels(size_t bytes_written, struct msghdr *msg) {
+  for (size_t i = 0; bytes_written > 0; ++i) {
+    size_t iov_written =
+        bytes_written < iov->iov_len ? bytes_written : iov->iov_len;
+    dfsan_set_label(0, iov->iov_base, iov_written);
+    bytes_written -= iov_written;
+  }
+}
+
+SANITIZER_INTERFACE_ATTRIBUTE int __dfsw_recvmmsg(
+    int sockfd, struct mmsghdr *msgvec, unsigned int vlen, int flags,
+    struct timespec *timeout, dfsan_label sockfd_label,
+    dfsan_label msgvec_label, dfsan_label vlen_label, dfsan_label flags_label,
+    dfsan_label timeout_label, dfsan_label *ret_label) {
+  int ret = recvmmsg(sockfd, msgvec, vlen, flags, timeout);
+  for (int i = 0; i < ret; ++i) {
+    dfsan_set_label(0, &msgvec[i].msg_len, sizeof(msgvec[i].msg_len));
+    clear_msghdr_labels(msgvec[i].msg_len, &msgvec[i].msg_hdr);
+  *ret_label = 0;
+  return ret;
+
+SANITIZER_INTERFACE_ATTRIBUTE ssize_t __dfsw_recvmsg(
+    int sockfd, struct msghdr *msg, int flags, dfsan_label sockfd_label,
+    dfsan_label msg_label, dfsan_label flags_label, dfsan_label *ret_label) {
+  ssize_t ret = recvmsg(sockfd, msg, flags);
+  if (ret >= 0)
+    clear_msghdr_labels(ret, msg);
   *ret_label = 0;
   return ret;
 }
 
 SANITIZER_INTERFACE_ATTRIBUTE int
 __dfsw_socketpair(int domain, int type, int protocol, int sv[2],
                   dfsan_label domain_label, dfsan_label type_label,
                   dfsan_label protocol_label, dfsan_label sv_label,

compiler-rt/lib/dfsan/done_abilist.txt

 fun:gethostname=custom
 fun:getrlimit=custom
 fun:getrusage=custom
 fun:getsockname=custom
 fun:getsockopt=custom
 fun:nanosleep=custom
 fun:pread=custom
 fun:read=custom
+fun:recvmmsg=custom
 fun:recvmsg=custom
 fun:sigaltstack=custom
 fun:socketpair=custom
 fun:stat=custom
 fun:time=custom
 
 # Functions that produce an output that depend on the input (propagate the
 # shadow manually).

compiler-rt/test/dfsan/custom.cpp

void test_calloc() {
   dfsan_set_label(i_label, crv, 100);
   free(crv);
 
   crv = (char *) calloc(4096, 1);
   ASSERT_ZERO_LABEL(crv[0]);
   free(crv);
 }
 
+void test_recvmmsg() {
+  int sockfds[2];
+  int ret = socketpair(AF_UNIX, SOCK_DGRAM, 0, sockfds);
+  assert(ret != -1);
+
+  // Setup messages to send.
+  struct mmsghdr smmsg[2] = {};
+  char sbuf0[] = "abcdefghijkl";
+  struct iovec siov0[2] = {{&sbuf0[0], 4}, {&sbuf0[4], 4}};
+  smmsg[0].msg_hdr.msg_iov = siov0;
+  smmsg[0].msg_hdr.msg_iovlen = 2;
+  char sbuf1[] = "1234567890";
+  struct iovec siov1[1] = {{&sbuf1[0], 7}};
+  smmsg[1].msg_hdr.msg_iov = siov1;
+  smmsg[1].msg_hdr.msg_iovlen = 1;
+
+  // Send messages.
+  int sent_msgs = sendmmsg(sockfds[0], smmsg, 2, 0);
+  assert(sent_msgs == 2);
+
+  // Setup receive buffers.
+  struct mmsghdr rmmsg[2] = {};
+  char rbuf0[128];
+  struct iovec riov0[2] = {{&rbuf0[0], 4}, {&rbuf0[4], 4}};
+  rmmsg[0].msg_hdr.msg_iov = riov0;
+  rmmsg[0].msg_hdr.msg_iovlen = 2;
+  char rbuf1[128];
+  struct iovec riov1[1] = {{&rbuf1[0], 16}};
+  rmmsg[1].msg_hdr.msg_iov = riov1;
+  rmmsg[1].msg_hdr.msg_iovlen = 1;
+  dfsan_set_label(i_label, rbuf0, sizeof(rbuf0));
+  dfsan_set_label(i_label, rbuf1, sizeof(rbuf1));
+  dfsan_set_label(i_label, &rmmsg[0].msg_len, sizeof(rmmsg[0].msg_len));
+  dfsan_set_label(i_label, &rmmsg[1].msg_len, sizeof(rmmsg[1].msg_len));
+
+  // Receive messages and check labels.
+  int received_msgs = recvmmsg(sockfds[1], rmmsg, 2, 0, NULL);
+  assert(received_msgs == sent_msgs);
+  assert(rmmsg[0].msg_len == smmsg[0].msg_len);
+  assert(rmmsg[1].msg_len == smmsg[1].msg_len);
+  assert(memcmp(sbuf0, rbuf0, 8) == 0);
+  assert(memcmp(sbuf1, rbuf1, 7) == 0);
+  ASSERT_ZERO_LABEL(received_msgs);
+  ASSERT_ZERO_LABEL(rmmsg[0].msg_len);
+  ASSERT_ZERO_LABEL(rmmsg[1].msg_len);
+  ASSERT_READ_ZERO_LABEL(&rbuf0[0], 8);
+  ASSERT_READ_LABEL(&rbuf0[8], 1, i_label);
+  ASSERT_READ_ZERO_LABEL(&rbuf1[0], 7);
+  ASSERT_READ_LABEL(&rbuf1[7], 1, i_label);
+
+  close(sockfds[0]);
+  close(sockfds[1]);
+}
+
 void test_recvmsg() {
   int sockfds[2];
   int ret = socketpair(AF_UNIX, SOCK_DGRAM, 0, sockfds);
   assert(ret != -1);
 
   char sbuf[] = "abcdefghijkl";
   struct iovec siovs[2] = {{&sbuf[0], 4}, {&sbuf[4], 4}};
   struct msghdr smsg = {};
#endif
   test_memcmp();
   test_memcpy();
   test_memset();
   test_nanosleep();
   test_poll();
   test_pread();
   test_pthread_create();
   test_read();
+  test_recvmmsg();
   test_recvmsg();
   test_sched_getaffinity();
   test_select();
   test_sigaction();
   test_sigaltstack();
   test_sigemptyset();
   test_snprintf();
   test_socketpair();