int main() {
int pid;
int fds[3];
int spair[2];
sys_chk(socketpair(AF_UNIX, SOCK_STREAM, 0, spair));
sys_chk(pid = fork());
if (pid == 0) { // Child.
sys_chk(fds[0] = open("/etc/passwd", O_RDONLY));
sys_chk(lseek(fds[0], 5, SEEK_SET));
sys_chk(fds[1] = open("/etc/group", O_RDONLY));
sys_chk(lseek(fds[1], 10, SEEK_SET));
sys_chk(fds[2] = open("/bin/sh", O_RDONLY));
sys_chk(lseek(fds[2], 20, SEEK_SET));
send_fds(spair[0], fds, 3);
return EXIT_SUCCESS;
} else { // Parent.
int *fds;
int fds_len;
recv_fds(spair[1], &fds, &fds_len);
printf("parent: got fds:");
for (int i = 0; i < fds_len; ++i) {
printf(" %d (fp=%lld)", fds[i], (long long)lseek(fds[i], 0, SEEK_CUR));
}
printf("\n");
return EXIT_SUCCESS;
}
}
int parasite_drain_fds_seized(struct parasite_ctl *ctl,
struct parasite_drain_fd *dfds, int *lfds, struct fd_opts *opts)
{
int ret = -1, size;
struct parasite_drain_fd *args;
size = drain_fds_size(dfds);
args = parasite_args_s(ctl, size);
memcpy(args, dfds, size);
ret = parasite_execute(PARASITE_CMD_DRAIN_FDS, ctl);
if (ret) {
pr_err("Parasite failed to drain descriptors\n");
goto err;
}
ret = recv_fds(ctl->tsock, lfds, dfds->nr_fds, opts);
if (ret) {
pr_err("Can't retrieve FDs from socket\n");
goto err;
}
err:
return ret;
}
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;
}
