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https://github.com/clearml/dropbear
synced 2025-03-12 14:48:34 +00:00
- Generalise spawn_command function
--HG-- extra : convert_revision : 9927a5fe084c8053c747a40515f0213141ef8139
This commit is contained in:
Matt Johnston
parent
d7c1e58217
commit
7ac24b10b9
77
dbutil.c
77
dbutil.c
@ -389,6 +389,83 @@ int connect_remote(const char* remotehost, const char* remoteport,
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return sock;
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}
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/* Sets up a pipe for a, returning three non-blocking file descriptors
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* and the pid. exec_fn is the function that will actually execute the child process,
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* it will be run after the child has fork()ed, and is passed exec_data. */
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int spawn_command(void(*exec_fn)(void *user_data), void *exec_data,
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int *ret_writefd, int *ret_readfd, int *ret_errfd, pid_t *ret_pid)
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{
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int infds[2];
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int outfds[2];
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int errfds[2];
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pid_t pid;
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const int FDIN = 0;
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const int FDOUT = 1;
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/* redirect stdin/stdout/stderr */
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if (pipe(infds) != 0)
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return DROPBEAR_FAILURE;
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if (pipe(outfds) != 0)
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return DROPBEAR_FAILURE;
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if (pipe(errfds) != 0)
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return DROPBEAR_FAILURE;
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#ifdef __uClinux__
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pid = vfork();
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#else
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pid = fork();
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#endif
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if (pid < 0)
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return DROPBEAR_FAILURE;
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if (!pid) {
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/* child */
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TRACE(("back to normal sigchld"))
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/* Revert to normal sigchld handling */
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if (signal(SIGCHLD, SIG_DFL) == SIG_ERR) {
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dropbear_exit("signal() error");
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}
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/* redirect stdin/stdout */
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if ((dup2(infds[FDIN], STDIN_FILENO) < 0) ||
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(dup2(outfds[FDOUT], STDOUT_FILENO) < 0) ||
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(dup2(errfds[FDOUT], STDERR_FILENO) < 0)) {
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TRACE(("leave noptycommand: error redirecting FDs"))
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dropbear_exit("child dup2() failure");
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}
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close(infds[FDOUT]);
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close(infds[FDIN]);
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close(outfds[FDIN]);
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close(outfds[FDOUT]);
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close(errfds[FDIN]);
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close(errfds[FDOUT]);
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exec_fn(exec_data);
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/* not reached */
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return DROPBEAR_FAILURE;
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} else {
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/* parent */
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close(infds[FDIN]);
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close(outfds[FDOUT]);
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close(errfds[FDOUT]);
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setnonblocking(errfds[FDIN]);
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setnonblocking(outfds[FDIN]);
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setnonblocking(infds[FDOUT]);
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*ret_pid = pid;
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*ret_writefd = infds[FDOUT];
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*ret_readfd = outfds[FDIN];
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*ret_errfd = errfds[FDIN];
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return DROPBEAR_SUCCESS;
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}
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}
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/* Return a string representation of the socket address passed. The return
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* value is allocated with malloc() */
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unsigned char * getaddrstring(struct sockaddr_storage* addr, int withport) {
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2
dbutil.h
2
dbutil.h
@ -49,6 +49,8 @@ char * stripcontrol(const char * text);
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unsigned char * getaddrstring(struct sockaddr_storage* addr, int withport);
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int dropbear_listen(const char* address, const char* port,
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int *socks, unsigned int sockcount, char **errstring, int *maxfd);
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int spawn_command(void(*exec_fn)(void *user_data), void *exec_data,
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int *writefd, int *readfd, int *errfd, pid_t *pid);
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int connect_remote(const char* remotehost, const char* remoteport,
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int nonblocking, char ** errstring);
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char* getaddrhostname(struct sockaddr_storage * addr);
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@ -47,7 +47,7 @@ static int sessionsignal(struct ChanSess *chansess);
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static int noptycommand(struct Channel *channel, struct ChanSess *chansess);
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static int ptycommand(struct Channel *channel, struct ChanSess *chansess);
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static int sessionwinchange(struct ChanSess *chansess);
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static void execchild(struct ChanSess *chansess);
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static void execchild(void *user_data_chansess);
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static void addchildpid(struct ChanSess *chansess, pid_t pid);
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static void sesssigchild_handler(int val);
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static void closechansess(struct Channel *channel);
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@ -633,102 +633,37 @@ static int sessioncommand(struct Channel *channel, struct ChanSess *chansess,
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* pty.
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* Returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE */
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static int noptycommand(struct Channel *channel, struct ChanSess *chansess) {
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int infds[2];
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int outfds[2];
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int errfds[2];
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pid_t pid;
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unsigned int i;
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const int FDIN = 0;
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const int FDOUT = 1;
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int ret;
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TRACE(("enter noptycommand"))
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ret = spawn_command(execchild, chansess,
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&channel->writefd, &channel->readfd, &channel->errfd,
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&chansess->pid);
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/* redirect stdin/stdout/stderr */
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if (pipe(infds) != 0)
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return DROPBEAR_FAILURE;
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if (pipe(outfds) != 0)
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return DROPBEAR_FAILURE;
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if (pipe(errfds) != 0)
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return DROPBEAR_FAILURE;
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if (ret == DROPBEAR_FAILURE) {
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return ret;
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}
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#ifdef __uClinux__
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pid = vfork();
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#else
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pid = fork();
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#endif
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ses.maxfd = MAX(ses.maxfd, channel->writefd);
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ses.maxfd = MAX(ses.maxfd, channel->readfd);
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ses.maxfd = MAX(ses.maxfd, channel->errfd);
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if (pid < 0)
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return DROPBEAR_FAILURE;
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addchildpid(chansess, chansess->pid);
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if (!pid) {
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/* child */
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TRACE(("back to normal sigchld"))
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/* Revert to normal sigchld handling */
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if (signal(SIGCHLD, SIG_DFL) == SIG_ERR) {
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dropbear_exit("signal() error");
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}
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/* redirect stdin/stdout */
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if ((dup2(infds[FDIN], STDIN_FILENO) < 0) ||
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(dup2(outfds[FDOUT], STDOUT_FILENO) < 0) ||
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(dup2(errfds[FDOUT], STDERR_FILENO) < 0)) {
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TRACE(("leave noptycommand: error redirecting FDs"))
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return DROPBEAR_FAILURE;
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}
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close(infds[FDOUT]);
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close(infds[FDIN]);
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close(outfds[FDIN]);
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close(outfds[FDOUT]);
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close(errfds[FDIN]);
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close(errfds[FDOUT]);
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execchild(chansess);
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/* not reached */
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} else {
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/* parent */
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TRACE(("continue noptycommand: parent"))
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chansess->pid = pid;
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TRACE(("child pid is %d", pid))
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addchildpid(chansess, pid);
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if (svr_ses.lastexit.exitpid != -1) {
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TRACE(("parent side: lastexitpid is %d", svr_ses.lastexit.exitpid))
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/* The child probably exited and the signal handler triggered
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* possibly before we got around to adding the childpid. So we fill
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* out its data manually */
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for (i = 0; i < svr_ses.childpidsize; i++) {
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if (svr_ses.childpids[i].pid == svr_ses.lastexit.exitpid) {
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TRACE(("found match for lastexitpid"))
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svr_ses.childpids[i].chansess->exit = svr_ses.lastexit;
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svr_ses.lastexit.exitpid = -1;
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}
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if (svr_ses.lastexit.exitpid != -1) {
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TRACE(("parent side: lastexitpid is %d", svr_ses.lastexit.exitpid))
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/* The child probably exited and the signal handler triggered
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* possibly before we got around to adding the childpid. So we fill
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* out its data manually */
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int i;
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for (i = 0; i < svr_ses.childpidsize; i++) {
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if (svr_ses.childpids[i].pid == svr_ses.lastexit.exitpid) {
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TRACE(("found match for lastexitpid"))
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svr_ses.childpids[i].chansess->exit = svr_ses.lastexit;
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svr_ses.lastexit.exitpid = -1;
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}
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}
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close(infds[FDIN]);
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close(outfds[FDOUT]);
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close(errfds[FDOUT]);
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channel->writefd = infds[FDOUT];
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channel->readfd = outfds[FDIN];
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channel->errfd = errfds[FDIN];
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ses.maxfd = MAX(ses.maxfd, channel->writefd);
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ses.maxfd = MAX(ses.maxfd, channel->readfd);
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ses.maxfd = MAX(ses.maxfd, channel->errfd);
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setnonblocking(channel->readfd);
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setnonblocking(channel->writefd);
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setnonblocking(channel->errfd);
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}
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#undef FDIN
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#undef FDOUT
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TRACE(("leave noptycommand"))
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return DROPBEAR_SUCCESS;
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@ -873,12 +808,13 @@ static void addchildpid(struct ChanSess *chansess, pid_t pid) {
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/* Clean up, drop to user privileges, set up the environment and execute
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* the command/shell. This function does not return. */
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static void execchild(struct ChanSess *chansess) {
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static void execchild(void *user_data) {
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char *argv[4];
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char * usershell = NULL;
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char * baseshell = NULL;
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unsigned int i;
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struct ChanSess *chansess = user_data;
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/* with uClinux we'll have vfork()ed, so don't want to overwrite the
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* hostkey. can't think of a workaround to clear it */
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