123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418 |
- /*
- * The Qubes OS Project, http://www.qubes-os.org
- *
- * Copyright (C) 2013 Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- */
- #include <stdio.h>
- #include <stdlib.h>
- #include <signal.h>
- #include <unistd.h>
- #include <errno.h>
- #include <string.h>
- #include <sys/types.h>
- #include <sys/stat.h>
- #include <sys/wait.h>
- #include <sys/select.h>
- #include <fcntl.h>
- #include <libvchan.h>
- #include "qrexec.h"
- #include "libqrexec-utils.h"
- #include "qrexec-agent.h"
- #define VCHAN_BUFFER_SIZE 65536
- static volatile int child_exited;
- int stdout_msg_type = MSG_DATA_STDOUT;
- pid_t child_process_pid;
- static void sigchld_handler(int __attribute__((__unused__))x)
- {
- child_exited = 1;
- signal(SIGCHLD, sigchld_handler);
- }
- void no_colon_in_cmd()
- {
- fprintf(stderr,
- "cmdline is supposed to be in user:command form\n");
- exit(1);
- }
- void do_exec(char *cmd)
- {
- char buf[strlen(QUBES_RPC_MULTIPLEXER_PATH) + strlen(cmd) - strlen(RPC_REQUEST_COMMAND) + 1];
- char *realcmd = index(cmd, ':');
- if (!realcmd)
- no_colon_in_cmd();
- /* mark end of username and move to command */
- *realcmd = 0;
- realcmd++;
- /* ignore "nogui:" prefix in linux agent */
- if (strncmp(realcmd, "nogui:", 6) == 0)
- realcmd+=6;
- /* replace magic RPC cmd with RPC multiplexer path */
- if (strncmp(realcmd, RPC_REQUEST_COMMAND " ", strlen(RPC_REQUEST_COMMAND)+1)==0) {
- strcpy(buf, QUBES_RPC_MULTIPLEXER_PATH);
- strcpy(buf + strlen(QUBES_RPC_MULTIPLEXER_PATH), realcmd + strlen(RPC_REQUEST_COMMAND));
- realcmd = buf;
- }
- signal(SIGCHLD, SIG_DFL);
- signal(SIGPIPE, SIG_DFL);
- execl("/bin/su", "su", "-", cmd, "-c", realcmd, NULL);
- perror("execl");
- exit(1);
- }
- int handle_just_exec(char *cmdline)
- {
- int fdn, pid;
- switch (pid = fork()) {
- case -1:
- perror("fork");
- return -1;
- case 0:
- fdn = open("/dev/null", O_RDWR);
- fix_fds(fdn, fdn, fdn);
- do_exec(cmdline);
- perror("execl");
- exit(1);
- default:;
- }
- fprintf(stderr, "executed (nowait) %s pid %d\n", cmdline, pid);
- return 0;
- }
- void send_exit_code(libvchan_t *data_vchan, int status)
- {
- struct msg_header hdr;
- hdr.type = MSG_DATA_EXIT_CODE;
- hdr.len = sizeof(status);
- if (libvchan_send(data_vchan, &hdr, sizeof(hdr)) < 0)
- handle_vchan_error("write hdr");
- if (libvchan_send(data_vchan, &status, sizeof(status)) < 0)
- handle_vchan_error("write status");
- fprintf(stderr, "send exit code %d\n", status);
- }
- /* handle data from specified FD and send over vchan link
- * Return:
- * -1 - vchan error occurred
- * 0 - EOF received, do not attempt to access this FD again
- * 1 - some data processed, call it again when buffer space and more data
- * available
- */
- int handle_input(libvchan_t *vchan, int fd, int msg_type)
- {
- char buf[MAX_DATA_CHUNK];
- int len;
- struct msg_header hdr;
- hdr.type = msg_type;
- while (libvchan_buffer_space(vchan) > (int)sizeof(struct msg_header)) {
- len = libvchan_buffer_space(vchan)-sizeof(struct msg_header);
- if (len > (int)sizeof(buf))
- len = sizeof(buf);
- len = read(fd, buf, len);
- if (len < 0) {
- if (errno == EAGAIN || errno == EWOULDBLOCK)
- return 1;
- else
- return -1;
- }
- hdr.len = len;
- if (libvchan_send(vchan, &hdr, sizeof(hdr)) < 0)
- return -1;
- if (len && !write_vchan_all(vchan, buf, len))
- return -1;
- if (len == 0) {
- close(fd);
- return 0;
- }
- }
- return 1;
- }
- /* handle data from vchan and send it to specified FD
- * Return:
- * -2 - remote process terminated, do not send more data to it
- * -1 - vchan error occurred
- * 0 - EOF received, do not attempt to access this FD again
- * 1 - some data processed, call it again when buffer space and more data
- * available
- */
- int handle_remote_data(libvchan_t *data_vchan, int stdin_fd)
- {
- struct msg_header hdr;
- char buf[MAX_DATA_CHUNK];
- int status;
- /* TODO: set stdin_fd to non-blocking mode and handle its buffering */
- while (libvchan_data_ready(data_vchan) > 0) {
- if (libvchan_recv(data_vchan, &hdr, sizeof(hdr)) < 0)
- return -1;
- if (hdr.len > MAX_DATA_CHUNK) {
- fprintf(stderr, "Too big data chunk received: %d > %d\n",
- hdr.len, MAX_DATA_CHUNK);
- return -1;
- }
- if (!read_vchan_all(data_vchan, buf, hdr.len))
- return -1;
- switch (hdr.type) {
- /* handle both directions because this can be either server or client
- * of VM-VM connection */
- case MSG_DATA_STDIN:
- case MSG_DATA_STDOUT:
- if (stdin_fd < 0)
- /* discard the data */
- continue;
- if (hdr.len == 0) {
- close(stdin_fd);
- stdin_fd = -1;
- return 0;
- } else {
- /* FIXME: use buffered write here to prevent deadlock */
- if (!write_all(stdin_fd, buf, hdr.len)) {
- if (errno == EPIPE) {
- close(stdin_fd);
- stdin_fd = -1;
- } else {
- perror("write");
- }
- return 0;
- }
- }
- break;
- case MSG_DATA_STDERR:
- /* stderr of remote service, log locally */
- if (!write_all(2, buf, hdr.len)) {
- perror("write");
- /* only log the error */
- }
- break;
- case MSG_DATA_EXIT_CODE:
- /* remote process exited, so there is no sense to send any data
- * to it */
- status = *(unsigned int *)buf;
- fprintf(stderr, "Remote service process exited with code %d\n", status);
- return -2;
- }
- }
- return 1;
- }
- void process_child_io(libvchan_t *data_vchan,
- int stdin_fd, int stdout_fd, int stderr_fd)
- {
- fd_set rdset, wrset;
- int vchan_fd;
- sigset_t selectmask;
- int child_process_status = -1;
- int ret, max_fd;
- struct timespec zero_timeout = { 0, 0 };
- sigemptyset(&selectmask);
- sigaddset(&selectmask, SIGCHLD);
- sigprocmask(SIG_BLOCK, &selectmask, NULL);
- sigemptyset(&selectmask);
- set_nonblock(stdout_fd);
- set_nonblock(stderr_fd);
- while (1) {
- if (child_exited) {
- pid_t pid;
- int status;
- while ((pid = waitpid(-1, &status, WNOHANG)) > 0) {
- if (pid == child_process_pid) {
- child_process_status = WEXITSTATUS(status);
- if (stdin_fd >= 0) {
- close(stdin_fd);
- stdin_fd = -1;
- }
- }
- }
- child_exited = 0;
- }
- /* if all done, exit the loop */
- if ((!child_process_pid || child_process_status > -1) &&
- stdin_fd == -1 && stdout_fd == -1 && stderr_fd == -1) {
- if (child_process_status > -1) {
- send_exit_code(data_vchan, child_process_status);
- }
- break;
- }
- /* otherwise handle the events */
- FD_ZERO(&rdset);
- FD_ZERO(&wrset);
- max_fd = -1;
- vchan_fd = libvchan_fd_for_select(data_vchan);
- if (libvchan_buffer_space(data_vchan) > (int)sizeof(struct msg_header)) {
- if (stdout_fd >= 0) {
- FD_SET(stdout_fd, &rdset);
- if (stdout_fd > max_fd)
- max_fd = stdout_fd;
- }
- if (stderr_fd >= 0) {
- FD_SET(stderr_fd, &rdset);
- if (stderr_fd > max_fd)
- max_fd = stderr_fd;
- }
- }
- FD_SET(vchan_fd, &rdset);
- if (vchan_fd > max_fd)
- max_fd = vchan_fd;
- if (libvchan_data_ready(data_vchan) > 0) {
- /* check for other FDs, but exit immediately */
- ret = pselect(max_fd + 1, &rdset, &wrset, NULL, &zero_timeout, &selectmask);
- } else
- ret = pselect(max_fd + 1, &rdset, &wrset, NULL, NULL, &selectmask);
- if (ret < 0) {
- if (errno == EINTR)
- continue;
- else {
- perror("pselect");
- /* TODO */
- break;
- }
- }
- /* clear event pending flag */
- if (FD_ISSET(vchan_fd, &rdset)) {
- if (libvchan_wait(data_vchan) < 0)
- handle_vchan_error("wait");
- }
- if (stdout_fd >= 0 && FD_ISSET(stdout_fd, &rdset)) {
- switch (handle_input(data_vchan, stdout_fd, stdout_msg_type)) {
- case -1:
- handle_vchan_error("send");
- break;
- case 0:
- stdout_fd = -1;
- break;
- }
- }
- if (stderr_fd >= 0 && FD_ISSET(stderr_fd, &rdset)) {
- switch (handle_input(data_vchan, stderr_fd, MSG_DATA_STDERR)) {
- case -1:
- handle_vchan_error("send");
- break;
- case 0:
- stderr_fd = -1;
- break;
- }
- }
- /* handle_remote_data will check if any data is available */
- switch (handle_remote_data(data_vchan, stdin_fd)) {
- case -1:
- handle_vchan_error("read");
- break;
- case 0:
- stdin_fd = -1;
- break;
- case -2:
- /* remote process exited, no sense in sending more data to it */
- close(stdout_fd);
- stdout_fd = -1;
- close(stderr_fd);
- stderr_fd = -1;
- break;
- }
- }
- }
- pid_t handle_new_process(int type, int connect_domain, int connect_port,
- char *cmdline, int cmdline_len)
- {
- struct service_params *svc_params = (struct service_params*)cmdline;
- libvchan_t *data_vchan;
- pid_t pid;
- int stdin_fd, stdout_fd, stderr_fd;
- if (type == MSG_SERVICE_CONNECT) {
- if (cmdline_len != sizeof(*svc_params)) {
- fprintf(stderr, "Invalid MSG_SERVICE_CONNECT packet (cmdline len %d)\n", cmdline_len);
- return -1;
- }
- sscanf(cmdline, "%d %d %d", &stdin_fd, &stdout_fd, &stderr_fd);
- }
- switch (pid=fork()){
- case -1:
- perror("fork");
- return -1;
- case 0:
- break;
- default:
- if (type == MSG_SERVICE_CONNECT) {
- /* no longer needed in parent process */
- close(stdin_fd);
- close(stdout_fd);
- close(stderr_fd);
- }
- return pid;
- }
- /* child process */
- if (type == MSG_SERVICE_CONNECT) {
- data_vchan = libvchan_server_init(connect_domain, connect_port,
- VCHAN_BUFFER_SIZE, VCHAN_BUFFER_SIZE);
- if (data_vchan)
- libvchan_wait(data_vchan);
- } else {
- data_vchan = libvchan_client_init(connect_domain, connect_port);
- }
- if (!data_vchan) {
- fprintf(stderr, "Data vchan connection failed\n");
- exit(1);
- }
- handle_handshake(data_vchan);
- signal(SIGCHLD, sigchld_handler);
- switch (type) {
- case MSG_JUST_EXEC:
- send_exit_code(data_vchan, handle_just_exec(cmdline));
- libvchan_close(data_vchan);
- break;
- case MSG_EXEC_CMDLINE:
- do_fork_exec(cmdline, &pid, &stdin_fd, &stdout_fd, &stderr_fd);
- fprintf(stderr, "executed %s pid %d\n", cmdline, pid);
- child_process_pid = pid;
- process_child_io(data_vchan, stdin_fd, stdout_fd, stderr_fd);
- break;
- case MSG_SERVICE_CONNECT:
- child_process_pid = 0;
- stdout_msg_type = MSG_DATA_STDIN;
- process_child_io(data_vchan, stdin_fd, stdout_fd, stderr_fd);
- break;
- }
- exit(0);
- /* suppress warning */
- return 0;
- }
|