+
+/*
+ * Send a message with credentials over a unix socket.
+ *
+ * Returns the size of data sent, or negative error value.
+ */
+ssize_t lttcomm_send_creds_unix_sock(int sock, void *buf, size_t len)
+{
+ struct msghdr msg = { 0 };
+ struct cmsghdr *cmptr;
+ struct iovec iov[1];
+ ssize_t ret = -1;
+ struct ucred *creds;
+ size_t sizeof_cred = sizeof(struct ucred);
+ char anc_buf[CMSG_SPACE(sizeof_cred)];
+
+ iov[0].iov_base = buf;
+ iov[0].iov_len = len;
+ msg.msg_iov = iov;
+ msg.msg_iovlen = 1;
+
+ msg.msg_control = (caddr_t) anc_buf;
+ msg.msg_controllen = CMSG_LEN(sizeof_cred);
+
+ cmptr = CMSG_FIRSTHDR(&msg);
+ cmptr->cmsg_level = SOL_SOCKET;
+ cmptr->cmsg_type = SCM_CREDENTIALS;
+ cmptr->cmsg_len = CMSG_LEN(sizeof_cred);
+
+ creds = (struct ucred *) CMSG_DATA(cmptr);
+
+ creds->uid = geteuid();
+ creds->gid = getegid();
+ creds->pid = getpid();
+
+ ret = sendmsg(sock, &msg, 0);
+ if (ret < 0) {
+ perror("sendmsg");
+ }
+
+ return ret;
+}
+
+/*
+ * Recv a message accompanied with credentials from a unix socket.
+ *
+ * Returns the size of received data, or negative error value.
+ */
+ssize_t lttcomm_recv_creds_unix_sock(int sock, void *buf, size_t len,
+ struct ucred *creds)
+{
+ struct msghdr msg = { 0 };
+ struct cmsghdr *cmptr;
+ struct iovec iov[1];
+ ssize_t ret;
+ size_t sizeof_cred = sizeof(struct ucred);
+ char anc_buf[CMSG_SPACE(sizeof_cred)];
+
+ /* Not allowed */
+ if (creds == NULL) {
+ ret = -1;
+ goto end;
+ }
+
+ /* Prepare to receive the structures */
+ iov[0].iov_base = buf;
+ iov[0].iov_len = len;
+ msg.msg_iov = iov;
+ msg.msg_iovlen = 1;
+
+ msg.msg_control = anc_buf;
+ msg.msg_controllen = sizeof(anc_buf);
+
+ ret = recvmsg(sock, &msg, 0);
+ if (ret < 0) {
+ perror("recvmsg fds");
+ goto end;
+ }
+
+ if (msg.msg_flags & MSG_CTRUNC) {
+ fprintf(stderr, "Error: Control message truncated.\n");
+ ret = -1;
+ goto end;
+ }
+
+ cmptr = CMSG_FIRSTHDR(&msg);
+ if (cmptr == NULL) {
+ fprintf(stderr, "Error: Invalid control message header\n");
+ ret = -1;
+ goto end;
+ }
+
+ if (cmptr->cmsg_level != SOL_SOCKET ||
+ cmptr->cmsg_type != SCM_CREDENTIALS) {
+ fprintf(stderr, "Didn't received any credentials\n");
+ ret = -1;
+ goto end;
+ }
+
+ if (cmptr->cmsg_len != CMSG_LEN(sizeof_cred)) {
+ fprintf(stderr, "Error: Received %zu bytes of ancillary data, expected %zu\n",
+ cmptr->cmsg_len, CMSG_LEN(sizeof_cred));
+ ret = -1;
+ goto end;
+ }
+
+ memcpy(creds, CMSG_DATA(cmptr), sizeof_cred);
+
+end:
+ return ret;
+}
+
+/*
+ * Set socket option to use credentials passing.
+ */
+int lttcomm_setsockopt_creds_unix_sock(int sock)
+{
+ int ret, on = 1;
+
+ /* Set socket for credentials retrieval */
+ ret = setsockopt(sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
+ if (ret < 0) {
+ perror("setsockopt creds unix sock");
+ }
+
+ return ret;
+}