[DFSan] Add custom wrapper for recvmmsg.

Uses the recvmsg wrapper logic in a loop.

Reviewed By: stephan.yichao.zhao

Differential Revision: https://reviews.llvm.org/D93059

compiler-rt/lib/dfsan/dfsan_custom.cpp

@@ -916,22 +916,40 @@ SANITIZER_INTERFACE_ATTRIBUTE int __dfsw_nanosleep(const struct timespec *req,
   return ret;
 }
 
+static void clear_msghdr_labels(size_t bytes_written, struct msghdr *msg) {
+  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 i = 0; bytes_written > 0; ++i) {
+    assert(i < msg->msg_iovlen);
+    struct iovec *iov = &msg->msg_iov[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) {
-    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;
-    }
-  }
+  if (ret >= 0)
+    clear_msghdr_labels(ret, msg);
   *ret_label = 0;
   return ret;
 }

compiler-rt/lib/dfsan/done_abilist.txt

@@ -201,6 +201,7 @@ fun:getsockopt=custom
 fun:nanosleep=custom
 fun:pread=custom
 fun:read=custom
+fun:recvmmsg=custom
 fun:recvmsg=custom
 fun:sigaltstack=custom
 fun:socketpair=custom

compiler-rt/test/dfsan/custom.cpp

@@ -337,6 +337,64 @@ void test_calloc() {
   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;
+  struct timespec timeout = {1, 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));
+  dfsan_set_label(i_label, &timeout, sizeof(timeout));
+
+  // Receive messages and check labels.
+  int received_msgs = recvmmsg(sockfds[1], rmmsg, 2, 0, &timeout);
+  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);
+  ASSERT_LABEL(timeout.tv_sec, i_label);
+  ASSERT_LABEL(timeout.tv_nsec, i_label);
+
+  close(sockfds[0]);
+  close(sockfds[1]);
+}
+
 void test_recvmsg() {
   int sockfds[2];
   int ret = socketpair(AF_UNIX, SOCK_DGRAM, 0, sockfds);
@@ -1226,6 +1284,7 @@ int main(void) {
   test_pthread_create();
   test_pthread_join();
   test_read();
+  test_recvmmsg();
   test_recvmsg();
   test_sched_getaffinity();
   test_select();