X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;ds=sidebyside;f=networking%2Ftelnetd.c;h=b0a1cc4d8632a71d6713aa967f98b411827b4c9c;hb=510f56aa6fe62465989507b163ab737c2cf882aa;hp=b7162ad361735db6608705bfe8374b1be1078cd1;hpb=5e34ff29bcc870936ab18172f438a34d042d4e03;p=oweals%2Fbusybox.git diff --git a/networking/telnetd.c b/networking/telnetd.c index b7162ad36..b0a1cc4d8 100644 --- a/networking/telnetd.c +++ b/networking/telnetd.c @@ -11,14 +11,14 @@ * * The telnetd manpage says it all: * - * Telnetd operates by allocating a pseudo-terminal device (see pty(4)) for - * a client, then creating a login process which has the slave side of the - * pseudo-terminal as stdin, stdout, and stderr. Telnetd manipulates the - * master side of the pseudo-terminal, implementing the telnet protocol and - * passing characters between the remote client and the login process. + * Telnetd operates by allocating a pseudo-terminal device (see pty(4)) for + * a client, then creating a login process which has the slave side of the + * pseudo-terminal as stdin, stdout, and stderr. Telnetd manipulates the + * master side of the pseudo-terminal, implementing the telnet protocol and + * passing characters between the remote client and the login process. * * Vladimir Oleynik 2001 - * Set process group corrections, initial busybox port + * Set process group corrections, initial busybox port */ #define DEBUG 0 @@ -32,18 +32,19 @@ #endif #include -/* Structure that describes a session */ struct tsession { struct tsession *next; pid_t shell_pid; - int sockfd_read, sockfd_write, ptyfd; + int sockfd_read; + int sockfd_write; + int ptyfd; /* two circular buffers */ /*char *buf1, *buf2;*/ -/*#define TS_BUF1 ts->buf1*/ -/*#define TS_BUF2 TS_BUF2*/ -#define TS_BUF1 ((unsigned char*)(ts + 1)) -#define TS_BUF2 (((unsigned char*)(ts + 1)) + BUFSIZE) +/*#define TS_BUF1(ts) ts->buf1*/ +/*#define TS_BUF2(ts) TS_BUF2(ts)*/ +#define TS_BUF1(ts) ((unsigned char*)(ts + 1)) +#define TS_BUF2(ts) (((unsigned char*)(ts + 1)) + BUFSIZE) int rdidx1, wridx1, size1; int rdidx2, wridx2, size2; }; @@ -54,10 +55,17 @@ enum { BUFSIZE = (4 * 1024 - sizeof(struct tsession)) / 2 }; /* Globals */ -static int maxfd; -static struct tsession *sessions; -static const char *loginpath = "/bin/login"; -static const char *issuefile = "/etc/issue.net"; +struct globals { + struct tsession *sessions; + const char *loginpath; + const char *issuefile; + int maxfd; +}; +#define G (*(struct globals*)&bb_common_bufsiz1) +#define INIT_G() do { \ + G.loginpath = "/bin/login"; \ + G.issuefile = "/etc/issue.net"; \ +} while (0) /* @@ -81,7 +89,7 @@ static const char *issuefile = "/etc/issue.net"; static unsigned char * remove_iacs(struct tsession *ts, int *pnum_totty) { - unsigned char *ptr0 = TS_BUF1 + ts->wridx1; + unsigned char *ptr0 = TS_BUF1(ts) + ts->wridx1; unsigned char *ptr = ptr0; unsigned char *totty = ptr; unsigned char *end = ptr + MIN(BUFSIZE - ts->wridx1, ts->size1); @@ -118,9 +126,9 @@ remove_iacs(struct tsession *ts, int *pnum_totty) * TELOPT_NAWS support! */ if ((ptr+2) >= end) { - /* only the beginning of the IAC is in the + /* Only the beginning of the IAC is in the buffer we were asked to process, we can't - process this char. */ + process this char */ break; } /* @@ -146,13 +154,13 @@ remove_iacs(struct tsession *ts, int *pnum_totty) num_totty = totty - ptr0; *pnum_totty = num_totty; - /* the difference between ptr and totty is number of iacs - we removed from the stream. Adjust buf1 accordingly. */ + /* The difference between ptr and totty is number of iacs + we removed from the stream. Adjust buf1 accordingly */ if ((ptr - totty) == 0) /* 99.999% of cases */ return ptr0; ts->wridx1 += ptr - totty; ts->size1 -= ptr - totty; - /* move chars meant for the terminal towards the end of the buffer */ + /* Move chars meant for the terminal towards the end of the buffer */ return memmove(ptr - num_totty, ptr0, num_totty); } @@ -199,6 +207,16 @@ static size_t iac_safe_write(int fd, const char *buf, size_t count) return total + rc; } +/* Must match getopt32 string */ +enum { + OPT_WATCHCHILD = (1 << 2), /* -K */ + OPT_INETD = (1 << 3) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -i */ + OPT_PORT = (1 << 4) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -p PORT */ + OPT_FOREGROUND = (1 << 6) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -F */ + OPT_SYSLOG = (1 << 7) * ENABLE_FEATURE_TELNETD_INETD_WAIT, /* -S */ + OPT_WAIT = (1 << 8) * ENABLE_FEATURE_TELNETD_INETD_WAIT, /* -w SEC */ +}; + static struct tsession * make_new_session( IF_FEATURE_TELNETD_STANDALONE(int sock) @@ -213,24 +231,26 @@ make_new_session( /*ts->buf1 = (char *)(ts + 1);*/ /*ts->buf2 = ts->buf1 + BUFSIZE;*/ - /* Got a new connection, set up a tty. */ + /* Got a new connection, set up a tty */ fd = xgetpty(tty_name); - if (fd > maxfd) - maxfd = fd; + if (fd > G.maxfd) + G.maxfd = fd; ts->ptyfd = fd; ndelay_on(fd); + close_on_exec_on(fd); + #if ENABLE_FEATURE_TELNETD_STANDALONE - ts->sockfd_read = sock; /* SO_KEEPALIVE by popular demand */ setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1)); + ts->sockfd_read = sock; ndelay_on(sock); - if (!sock) { /* We are called with fd 0 - we are in inetd mode */ + if (sock == 0) { /* We are called with fd 0 - we are in inetd mode */ sock++; /* so use fd 1 for output */ ndelay_on(sock); } ts->sockfd_write = sock; - if (sock > maxfd) - maxfd = sock; + if (sock > G.maxfd) + G.maxfd = sock; #else /* SO_KEEPALIVE by popular demand */ setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1)); @@ -239,6 +259,7 @@ make_new_session( ndelay_on(0); ndelay_on(1); #endif + /* Make the telnet client understand we will echo characters so it * should not do it locally. We don't tell the client to run linemode, * because we want to handle line editing and tab completion and other @@ -254,7 +275,7 @@ make_new_session( }; /* This confuses iac_safe_write(), it will try to duplicate * each IAC... */ - //memcpy(TS_BUF2, iacs_to_send, sizeof(iacs_to_send)); + //memcpy(TS_BUF2(ts), iacs_to_send, sizeof(iacs_to_send)); //ts->rdidx2 = sizeof(iacs_to_send); //ts->size2 = sizeof(iacs_to_send); /* So just stuff it into TCP stream! (no error check...) */ @@ -267,7 +288,7 @@ make_new_session( /*ts->size2 = 0;*/ } - fflush(NULL); /* flush all streams */ + fflush_all(); pid = vfork(); /* NOMMU-friendly */ if (pid < 0) { free(ts); @@ -291,7 +312,7 @@ make_new_session( /* Make new session and process group */ setsid(); - /* Open the child's side of the tty. */ + /* Open the child's side of the tty */ /* NB: setsid() disconnects from any previous ctty's. Therefore * we must open child's side of the tty AFTER setsid! */ close(0); @@ -300,8 +321,8 @@ make_new_session( xdup2(0, 2); tcsetpgrp(0, getpid()); /* switch this tty's process group to us */ - /* The pseudo-terminal allocated to the client is configured to operate in - * cooked mode, and with XTABS CRMOD enabled (see tty(4)). */ + /* The pseudo-terminal allocated to the client is configured to operate + * in cooked mode, and with XTABS CRMOD enabled (see tty(4)) */ tcgetattr(0, &termbuf); termbuf.c_lflag |= ECHO; /* if we use readline we dont want this */ termbuf.c_oflag |= ONLCR | XTABS; @@ -310,46 +331,41 @@ make_new_session( /*termbuf.c_lflag &= ~ICANON;*/ tcsetattr_stdin_TCSANOW(&termbuf); - /* Uses FILE-based I/O to stdout, but does fflush(stdout), + /* Uses FILE-based I/O to stdout, but does fflush_all(), * so should be safe with vfork. * I fear, though, that some users will have ridiculously big * issue files, and they may block writing to fd 1, * (parent is supposed to read it, but parent waits * for vforked child to exec!) */ - print_login_issue(issuefile, tty_name); + print_login_issue(G.issuefile, tty_name); /* Exec shell / login / whatever */ - login_argv[0] = loginpath; + login_argv[0] = G.loginpath; login_argv[1] = NULL; /* exec busybox applet (if PREFER_APPLETS=y), if that fails, - * exec external program */ - BB_EXECVP(loginpath, (char **)login_argv); + * exec external program. + * NB: sock is either 0 or has CLOEXEC set on it. + * fd has CLOEXEC set on it too. These two fds will be closed here. + */ + BB_EXECVP(G.loginpath, (char **)login_argv); /* _exit is safer with vfork, and we shouldn't send message * to remote clients anyway */ - _exit(EXIT_FAILURE); /*bb_perror_msg_and_die("execv %s", loginpath);*/ + _exit(EXIT_FAILURE); /*bb_perror_msg_and_die("execv %s", G.loginpath);*/ } -/* Must match getopt32 string */ -enum { - OPT_WATCHCHILD = (1 << 2), /* -K */ - OPT_INETD = (1 << 3) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -i */ - OPT_PORT = (1 << 4) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -p */ - OPT_FOREGROUND = (1 << 6) * ENABLE_FEATURE_TELNETD_STANDALONE, /* -F */ -}; - #if ENABLE_FEATURE_TELNETD_STANDALONE static void free_session(struct tsession *ts) { - struct tsession *t = sessions; + struct tsession *t = G.sessions; if (option_mask32 & OPT_INETD) exit(EXIT_SUCCESS); /* Unlink this telnet session from the session list */ if (t == ts) - sessions = ts->next; + G.sessions = ts->next; else { while (t->next != ts) t = t->next; @@ -371,17 +387,17 @@ free_session(struct tsession *ts) free(ts); /* Scan all sessions and find new maxfd */ - maxfd = 0; - ts = sessions; + G.maxfd = 0; + ts = G.sessions; while (ts) { - if (maxfd < ts->ptyfd) - maxfd = ts->ptyfd; - if (maxfd < ts->sockfd_read) - maxfd = ts->sockfd_read; + if (G.maxfd < ts->ptyfd) + G.maxfd = ts->ptyfd; + if (G.maxfd < ts->sockfd_read) + G.maxfd = ts->sockfd_read; #if 0 /* Again, sockfd_write == sockfd_read here */ - if (maxfd < ts->sockfd_write) - maxfd = ts->sockfd_write; + if (G.maxfd < ts->sockfd_write) + G.maxfd = ts->sockfd_write; #endif ts = ts->next; } @@ -404,7 +420,7 @@ static void handle_sigchld(int sig UNUSED_PARAM) pid = wait_any_nohang(NULL); if (pid <= 0) break; - ts = sessions; + ts = G.sessions; while (ts) { if (ts->shell_pid == pid) { ts->shell_pid = -1; @@ -424,22 +440,29 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv) struct tsession *ts; #if ENABLE_FEATURE_TELNETD_STANDALONE #define IS_INETD (opt & OPT_INETD) - int master_fd = master_fd; /* be happy, gcc */ - unsigned portnbr = 23; + int master_fd = master_fd; /* for compiler */ + int sec_linger = sec_linger; char *opt_bindaddr = NULL; char *opt_portnbr; #else enum { IS_INETD = 1, master_fd = -1, - portnbr = 23, }; #endif + INIT_G(); + + /* -w NUM, and implies -F. -w and -i don't mix */ + IF_FEATURE_TELNETD_INETD_WAIT(opt_complementary = "wF:w+:i--w:w--i";) /* Even if !STANDALONE, we accept (and ignore) -i, thus people * don't need to guess whether it's ok to pass -i to us */ - opt = getopt32(argv, "f:l:Ki" IF_FEATURE_TELNETD_STANDALONE("p:b:F"), - &issuefile, &loginpath - IF_FEATURE_TELNETD_STANDALONE(, &opt_portnbr, &opt_bindaddr)); + opt = getopt32(argv, "f:l:Ki" + IF_FEATURE_TELNETD_STANDALONE("p:b:F") + IF_FEATURE_TELNETD_INETD_WAIT("Sw:"), + &G.issuefile, &G.loginpath + IF_FEATURE_TELNETD_STANDALONE(, &opt_portnbr, &opt_bindaddr) + IF_FEATURE_TELNETD_INETD_WAIT(, &sec_linger) + ); if (!IS_INETD /*&& !re_execed*/) { /* inform that we start in standalone mode? * May be useful when people forget to give -i */ @@ -451,31 +474,30 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv) } } /* Redirect log to syslog early, if needed */ - if (IS_INETD || !(opt & OPT_FOREGROUND)) { + if (IS_INETD || (opt & OPT_SYSLOG) || !(opt & OPT_FOREGROUND)) { openlog(applet_name, LOG_PID, LOG_DAEMON); logmode = LOGMODE_SYSLOG; } - IF_FEATURE_TELNETD_STANDALONE( - if (opt & OPT_PORT) - portnbr = xatou16(opt_portnbr); - ); - - /* Used to check access(loginpath, X_OK) here. Pointless. - * exec will do this for us for free later. */ - #if ENABLE_FEATURE_TELNETD_STANDALONE if (IS_INETD) { - sessions = make_new_session(0); - if (!sessions) /* pty opening or vfork problem, exit */ - return 1; /* make_new_session prints error message */ + G.sessions = make_new_session(0); + if (!G.sessions) /* pty opening or vfork problem, exit */ + return 1; /* make_new_session printed error message */ } else { - master_fd = create_and_bind_stream_or_die(opt_bindaddr, portnbr); - xlisten(master_fd, 1); + master_fd = 0; + if (!(opt & OPT_WAIT)) { + unsigned portnbr = 23; + if (opt & OPT_PORT) + portnbr = xatou16(opt_portnbr); + master_fd = create_and_bind_stream_or_die(opt_bindaddr, portnbr); + xlisten(master_fd, 1); + } + close_on_exec_on(master_fd); } #else - sessions = make_new_session(); - if (!sessions) /* pty opening or vfork problem, exit */ - return 1; /* make_new_session prints error message */ + G.sessions = make_new_session(); + if (!G.sessions) /* pty opening or vfork problem, exit */ + return 1; /* make_new_session printed error message */ #endif /* We don't want to die if just one session is broken */ @@ -487,8 +509,8 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv) signal(SIGCHLD, SIG_IGN); /* - This is how the buffers are used. The arrows indicate the movement - of data. + This is how the buffers are used. The arrows indicate data flow. + +-------+ wridx1++ +------+ rdidx1++ +----------+ | | <-------------- | buf1 | <-------------- | | | | size1-- +------+ size1++ | | @@ -512,9 +534,9 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv) * ptys if there is room in their session buffers. * NB: scalability problem: we recalculate entire bitmap * before each select. Can be a problem with 500+ connections. */ - ts = sessions; + ts = G.sessions; while (ts) { - struct tsession *next = ts->next; /* in case we free ts. */ + struct tsession *next = ts->next; /* in case we free ts */ if (ts->shell_pid == -1) { /* Child died and we detected that */ free_session(ts); @@ -535,16 +557,29 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv) /* This is needed because free_session() does not * take master_fd into account when it finds new * maxfd among remaining fd's */ - if (master_fd > maxfd) - maxfd = master_fd; + if (master_fd > G.maxfd) + G.maxfd = master_fd; } - count = select(maxfd + 1, &rdfdset, &wrfdset, NULL, NULL); + { + struct timeval *tv_ptr = NULL; +#if ENABLE_FEATURE_TELNETD_INETD_WAIT + struct timeval tv; + if ((opt & OPT_WAIT) && !G.sessions) { + tv.tv_sec = sec_linger; + tv.tv_usec = 0; + tv_ptr = &tv; + } +#endif + count = select(G.maxfd + 1, &rdfdset, &wrfdset, NULL, tv_ptr); + } + if (count == 0) /* "telnetd -w SEC" timed out */ + return 0; if (count < 0) goto again; /* EINTR or ENOMEM */ #if ENABLE_FEATURE_TELNETD_STANDALONE - /* First check for and accept new sessions. */ + /* Check for and accept new sessions */ if (!IS_INETD && FD_ISSET(master_fd, &rdfdset)) { int fd; struct tsession *new_ts; @@ -552,26 +587,28 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv) fd = accept(master_fd, NULL, NULL); if (fd < 0) goto again; - /* Create a new session and link it into our active list */ + close_on_exec_on(fd); + + /* Create a new session and link it into active list */ new_ts = make_new_session(fd); if (new_ts) { - new_ts->next = sessions; - sessions = new_ts; + new_ts->next = G.sessions; + G.sessions = new_ts; } else { close(fd); } } #endif - /* Then check for data tunneling. */ - ts = sessions; + /* Then check for data tunneling */ + ts = G.sessions; while (ts) { /* For all sessions... */ - struct tsession *next = ts->next; /* in case we free ts. */ + struct tsession *next = ts->next; /* in case we free ts */ if (/*ts->size1 &&*/ FD_ISSET(ts->ptyfd, &wrfdset)) { int num_totty; unsigned char *ptr; - /* Write to pty from buffer 1. */ + /* Write to pty from buffer 1 */ ptr = remove_iacs(ts, &num_totty); count = safe_write(ts->ptyfd, ptr, num_totty); if (count < 0) { @@ -586,9 +623,9 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv) } skip1: if (/*ts->size2 &&*/ FD_ISSET(ts->sockfd_write, &wrfdset)) { - /* Write to socket from buffer 2. */ + /* Write to socket from buffer 2 */ count = MIN(BUFSIZE - ts->wridx2, ts->size2); - count = iac_safe_write(ts->sockfd_write, (void*)(TS_BUF2 + ts->wridx2), count); + count = iac_safe_write(ts->sockfd_write, (void*)(TS_BUF2(ts) + ts->wridx2), count); if (count < 0) { if (errno == EAGAIN) goto skip2; @@ -616,16 +653,16 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv) } if (/*ts->size1 < BUFSIZE &&*/ FD_ISSET(ts->sockfd_read, &rdfdset)) { - /* Read from socket to buffer 1. */ + /* Read from socket to buffer 1 */ count = MIN(BUFSIZE - ts->rdidx1, BUFSIZE - ts->size1); - count = safe_read(ts->sockfd_read, TS_BUF1 + ts->rdidx1, count); + count = safe_read(ts->sockfd_read, TS_BUF1(ts) + ts->rdidx1, count); if (count <= 0) { if (count < 0 && errno == EAGAIN) goto skip3; goto kill_session; } /* Ignore trailing NUL if it is there */ - if (!TS_BUF1[ts->rdidx1 + count - 1]) { + if (!TS_BUF1(ts)[ts->rdidx1 + count - 1]) { --count; } ts->size1 += count; @@ -635,9 +672,9 @@ int telnetd_main(int argc UNUSED_PARAM, char **argv) } skip3: if (/*ts->size2 < BUFSIZE &&*/ FD_ISSET(ts->ptyfd, &rdfdset)) { - /* Read from pty to buffer 2. */ + /* Read from pty to buffer 2 */ count = MIN(BUFSIZE - ts->rdidx2, BUFSIZE - ts->size2); - count = safe_read(ts->ptyfd, TS_BUF2 + ts->rdidx2, count); + count = safe_read(ts->ptyfd, TS_BUF2(ts) + ts->rdidx2, count); if (count <= 0) { if (count < 0 && errno == EAGAIN) goto skip4;