main()
{
int fd[2], on, n;
char buf[100];
struct fcred cred;
if (socketpair(AF_LOCAL, SOCK_STREAM, 0, fd) < 0)
err_sys("socketpair error");
/* must set the socket option on the *receiving* socket */
on = 1;
Setsockopt(fd[1], 0, LOCAL_CREDS, &on, sizeof(on));
Write(fd[0], "hello, world\n", 13);
if ((n = recv_cred(fd[1], buf, sizeof(buf), &cred)) < 0)
err_sys("recv_cred error");
else if (n == 0)
err_quit("recv_cred, unexpected EOF");
buf[n] = 0; /* null terminate */
printf("data: %s", buf);
if (cred.fc_ngroups == 0)
printf("(no credentials returned)\n");
else {
printf("real user ID = %d\n", cred.fc_ruid);
printf("real group ID = %d\n", cred.fc_rgid);
printf("login name = %-*s\n", MAXLOGNAME, cred.fc_login);
printf("effective user ID = %d\n", cred.fc_uid);
printf("effective group ID = %d\n", cred.fc_gid);
printf("%d supplementary groups:", cred.fc_ngroups - 1);
for (n = 1; n < cred.fc_ngroups; n++) /* [0] is the egid */
printf(" %d", cred.fc_groups[n]);
printf("\n");
}
exit(0);
}
int do_recvmsg(message *dev_m_in, message *dev_m_out)
{
int minor;
int rc;
struct msg_control msg_ctrl;
socklen_t controllen_avail = 0;
socklen_t controllen_needed = 0;
socklen_t controllen_desired = 0;
#if DEBUG == 1
static int call_count = 0;
printf("(uds) [%d] do_sendmsg() call_count=%d\n",
uds_minor(dev_m_in), ++call_count);
#endif
minor = uds_minor(dev_m_in);
#if DEBUG == 1
printf("(uds) [%d] CREDENTIALS {pid:%d,uid:%d,gid:%d}\n", minor,
uds_fd_table[minor].ancillary_data.cred.pid,
uds_fd_table[minor].ancillary_data.cred.uid,
uds_fd_table[minor].ancillary_data.cred.gid);
#endif
memset(&msg_ctrl, '\0', sizeof(struct msg_control));
/* get the msg_control from the user, it will include the
* amount of space the user has allocated for control data.
*/
rc = sys_safecopyfrom(VFS_PROC_NR, (cp_grant_id_t) dev_m_in->IO_GRANT,
(vir_bytes) 0, (vir_bytes) &msg_ctrl,
sizeof(struct msg_control));
if (rc != OK) {
return EIO;
}
controllen_avail = MIN(msg_ctrl.msg_controllen, MSG_CONTROL_MAX);
if (uds_fd_table[minor].ancillary_data.nfiledes > 0) {
controllen_needed = CMSG_LEN(sizeof(int) *
(uds_fd_table[minor].ancillary_data.nfiledes));
}
/* if there is room we also include credentials */
controllen_desired = controllen_needed +
CMSG_LEN(sizeof(struct ucred));
if (controllen_needed > controllen_avail) {
return EOVERFLOW;
}
rc = recv_fds(minor, &uds_fd_table[minor].ancillary_data, &msg_ctrl);
if (rc != OK) {
return rc;
}
if (controllen_desired <= controllen_avail) {
rc = recv_cred(minor, &uds_fd_table[minor].ancillary_data,
&msg_ctrl);
if (rc != OK) {
return rc;
}
}
/* send the user the control data */
rc = sys_safecopyto(VFS_PROC_NR, (cp_grant_id_t) dev_m_in->IO_GRANT,
(vir_bytes) 0, (vir_bytes) &msg_ctrl,
sizeof(struct msg_control));
return rc ? EIO : OK;
}