/* vi: set sw=4 ts=4: */ /* * Based on agetty - another getty program for Linux. By W. Z. Venema 1989 * Ported to Linux by Peter Orbaek * This program is freely distributable. * * option added by Eric Rasmussen - 12/28/95 * * 1999-02-22 Arkadiusz Mickiewicz * - Added Native Language Support * * 1999-05-05 Thorsten Kranzkowski * - Enabled hardware flow control before displaying /etc/issue * * 2011-01 Venys Vlasenko * - Removed parity detection code. It can't work reliably: * if all chars received have bit 7 cleared and odd (or even) parity, * it is impossible to determine whether other side is 8-bit,no-parity * or 7-bit,odd(even)-parity. It also interferes with non-ASCII usernames. * - From now on, we assume that parity is correctly set. * * Licensed under GPLv2 or later, see file LICENSE in this source tree. */ #include "libbb.h" #include #ifndef IUCLC # define IUCLC 0 #endif #ifndef LOGIN_PROCESS # undef ENABLE_FEATURE_UTMP # undef ENABLE_FEATURE_WTMP # define ENABLE_FEATURE_UTMP 0 # define ENABLE_FEATURE_WTMP 0 #endif /* The following is used for understandable diagnostics */ #ifdef DEBUGGING static FILE *dbf; # define DEBUGTERM "/dev/ttyp0" # define debug(...) do { fprintf(dbf, __VA_ARGS__); fflush(dbf); } while (0) #else # define debug(...) ((void)0) #endif /* * Things you may want to modify. * * You may disagree with the default line-editing etc. characters defined * below. Note, however, that DEL cannot be used for interrupt generation * and for line editing at the same time. */ #undef _PATH_LOGIN #define _PATH_LOGIN "/bin/login" /* Displayed before the login prompt. * If ISSUE is not defined, getty will never display the contents of the * /etc/issue file. You will not want to spit out large "issue" files at the * wrong baud rate. */ #define ISSUE "/etc/issue" /* Macro to build Ctrl-LETTER. Assumes ASCII dialect */ #define CTL(x) ((x) ^ 0100) /* * When multiple baud rates are specified on the command line, * the first one we will try is the first one specified. */ #define MAX_SPEED 10 /* max. nr. of baud rates */ struct globals { unsigned timeout; const char *login; /* login program */ const char *fakehost; const char *tty_name; char *initstring; /* modem init string */ const char *issue; /* alternative issue file */ int numspeed; /* number of baud rates to try */ int speeds[MAX_SPEED]; /* baud rates to be tried */ unsigned char eol; /* end-of-line char seen (CR or NL) */ struct termios tty_attrs; char line_buf[128]; }; #define G (*ptr_to_globals) #define INIT_G() do { \ SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \ } while (0) //usage:#define getty_trivial_usage //usage: "[OPTIONS] BAUD_RATE[,BAUD_RATE]... TTY [TERMTYPE]" //usage:#define getty_full_usage "\n\n" //usage: "Open TTY, prompt for login name, then invoke /bin/login\n" //usage: "\n -h Enable hardware RTS/CTS flow control" //usage: "\n -L Set CLOCAL (ignore Carrier Detect state)" //usage: "\n -m Get baud rate from modem's CONNECT status message" //usage: "\n -n Don't prompt for login name" //usage: "\n -w Wait for CR or LF before sending /etc/issue" //usage: "\n -i Don't display /etc/issue" //usage: "\n -f ISSUE_FILE Display ISSUE_FILE instead of /etc/issue" //usage: "\n -l LOGIN Invoke LOGIN instead of /bin/login" //usage: "\n -t SEC Terminate after SEC if no login name is read" //usage: "\n -I INITSTR Send INITSTR before anything else" //usage: "\n -H HOST Log HOST into the utmp file as the hostname" //usage: "\n" //usage: "\nBAUD_RATE of 0 leaves it unchanged" static const char opt_string[] ALIGN1 = "I:LH:f:hil:mt:wn"; #define F_INITSTRING (1 << 0) /* -I */ #define F_LOCAL (1 << 1) /* -L */ #define F_FAKEHOST (1 << 2) /* -H */ #define F_CUSTISSUE (1 << 3) /* -f */ #define F_RTSCTS (1 << 4) /* -h */ #define F_NOISSUE (1 << 5) /* -i */ #define F_LOGIN (1 << 6) /* -l */ #define F_PARSE (1 << 7) /* -m */ #define F_TIMEOUT (1 << 8) /* -t */ #define F_WAITCRLF (1 << 9) /* -w */ #define F_NOPROMPT (1 << 10) /* -n */ /* convert speed string to speed code; return <= 0 on failure */ static int bcode(const char *s) { int value = bb_strtou(s, NULL, 10); /* yes, int is intended! */ if (value < 0) /* bad terminating char, overflow, etc */ return value; return tty_value_to_baud(value); } /* parse alternate baud rates */ static void parse_speeds(char *arg) { char *cp; /* NB: at least one iteration is always done */ debug("entered parse_speeds\n"); while ((cp = strsep(&arg, ",")) != NULL) { G.speeds[G.numspeed] = bcode(cp); if (G.speeds[G.numspeed] < 0) bb_error_msg_and_die("bad speed: %s", cp); /* note: arg "0" turns into speed B0 */ G.numspeed++; if (G.numspeed > MAX_SPEED) bb_error_msg_and_die("too many alternate speeds"); } debug("exiting parse_speeds\n"); } /* parse command-line arguments */ static void parse_args(char **argv) { char *ts; int flags; opt_complementary = "-2:t+"; /* at least 2 args; -t N */ flags = getopt32(argv, opt_string, &G.initstring, &G.fakehost, &G.issue, &G.login, &G.timeout ); if (flags & F_INITSTRING) { G.initstring = xstrdup(G.initstring); /* decode \ddd octal codes into chars */ strcpy_and_process_escape_sequences(G.initstring, G.initstring); } argv += optind; debug("after getopt\n"); /* We loosen up a bit and accept both "baudrate tty" and "tty baudrate" */ G.tty_name = argv[0]; ts = argv[1]; /* baud rate(s) */ if (isdigit(argv[0][0])) { /* A number first, assume it's a speed (BSD style) */ G.tty_name = ts; /* tty name is in argv[1] */ ts = argv[0]; /* baud rate(s) */ } parse_speeds(ts); if (argv[2]) xsetenv("TERM", argv[2]); debug("exiting parse_args\n"); } /* set up tty as standard input, output, error */ static void open_tty(void) { /* Set up new standard input, unless we are given an already opened port */ if (NOT_LONE_DASH(G.tty_name)) { if (G.tty_name[0] != '/') G.tty_name = xasprintf("/dev/%s", G.tty_name); /* will leak it */ /* Open the tty as standard input */ debug("open(2)\n"); close(0); xopen(G.tty_name, O_RDWR | O_NONBLOCK); /* uses fd 0 */ /* Set proper protections and ownership */ fchown(0, 0, 0); /* 0:0 */ fchmod(0, 0620); /* crw--w---- */ } else { char *n; /* * Standard input should already be connected to an open port. * Make sure it is open for read/write. */ if ((fcntl(0, F_GETFL) & (O_RDWR|O_RDONLY|O_WRONLY)) != O_RDWR) bb_error_msg_and_die("stdin is not open for read/write"); /* Try to get real tty name instead of "-" */ n = xmalloc_ttyname(0); if (n) G.tty_name = n; } applet_name = xasprintf("getty: %s", skip_dev_pfx(G.tty_name)); } static void set_tty_attrs(void) { if (tcsetattr_stdin_TCSANOW(&G.tty_attrs) < 0) bb_perror_msg_and_die("tcsetattr"); } /* We manipulate tty_attrs this way: * - first, we read existing tty_attrs * - init_tty_attrs modifies some parts and sets it * - auto_baud and/or BREAK processing can set different speed and set tty attrs * - finalize_tty_attrs again modifies some parts and sets tty attrs before * execing login */ static void init_tty_attrs(int speed) { /* Try to drain output buffer, with 5 sec timeout. * Added on request from users of ~600 baud serial interface * with biggish buffer on a 90MHz CPU. * They were losing hundreds of bytes of buffered output * on tcflush. */ signal_no_SA_RESTART_empty_mask(SIGALRM, record_signo); alarm(5); tcdrain(STDIN_FILENO); alarm(0); /* Flush input and output queues, important for modems! */ tcflush(STDIN_FILENO, TCIOFLUSH); /* Set speed if it wasn't specified as "0" on command line */ if (speed != B0) cfsetspeed(&G.tty_attrs, speed); /* Initial settings: 8-bit characters, raw mode, blocking i/o. * Special characters are set after we have read the login name; all * reads will be done in raw mode anyway. */ /* Clear all bits except: */ G.tty_attrs.c_cflag &= (0 /* 2 stop bits (1 otherwise) * Enable parity bit (both on input and output) * Odd parity (else even) */ | CSTOPB | PARENB | PARODD #ifdef CMSPAR | CMSPAR /* mark or space parity */ #endif #ifdef CBAUD | CBAUD /* (output) baud rate */ #endif #ifdef CBAUDEX | CBAUDEX /* (output) baud rate */ #endif #ifdef CIBAUD | CIBAUD /* input baud rate */ #endif ); /* Set: 8 bits; hang up (drop DTR) on last close; enable receive */ G.tty_attrs.c_cflag |= CS8 | HUPCL | CREAD; if (option_mask32 & F_LOCAL) { /* ignore Carrier Detect pin: * opens don't block when CD is low, * losing CD doesn't hang up processes whose ctty is this tty */ G.tty_attrs.c_cflag |= CLOCAL; } #ifdef CRTSCTS if (option_mask32 & F_RTSCTS) G.tty_attrs.c_cflag |= CRTSCTS; /* flow control using RTS/CTS pins */ #endif G.tty_attrs.c_iflag = 0; G.tty_attrs.c_lflag = 0; /* non-raw output; add CR to each NL */ G.tty_attrs.c_oflag = OPOST | ONLCR; /* reads would block only if < 1 char is available */ G.tty_attrs.c_cc[VMIN] = 1; /* no timeout (reads block forever) */ G.tty_attrs.c_cc[VTIME] = 0; #ifdef __linux__ G.tty_attrs.c_line = 0; #endif set_tty_attrs(); debug("term_io 2\n"); } static void finalize_tty_attrs(void) { /* software flow control on output (stop sending if XOFF is recvd); * and on input (send XOFF when buffer is full) */ G.tty_attrs.c_iflag |= IXON | IXOFF; if (G.eol == '\r') { G.tty_attrs.c_iflag |= ICRNL; /* map CR on input to NL */ } /* Other bits in c_iflag: * IXANY Any recvd char enables output (any char is also a XON) * INPCK Enable parity check * IGNPAR Ignore parity errors (drop bad bytes) * PARMRK Mark parity errors with 0xff, 0x00 prefix * (else bad byte is received as 0x00) * ISTRIP Strip parity bit * IGNBRK Ignore break condition * BRKINT Send SIGINT on break - maybe set this? * INLCR Map NL to CR * IGNCR Ignore CR * ICRNL Map CR to NL * IUCLC Map uppercase to lowercase * IMAXBEL Echo BEL on input line too long * IUTF8 Appears to affect tty's idea of char widths, * observed to improve backspacing through Unicode chars */ /* line buffered input (NL or EOL or EOF chars end a line); * recognize INT/QUIT/SUSP chars; * echo input chars; * echo BS-SP-BS on erase character; * echo kill char specially, not as ^c (ECHOKE controls how exactly); * erase all input via BS-SP-BS on kill char (else go to next line) */ G.tty_attrs.c_lflag |= ICANON | ISIG | ECHO | ECHOE | ECHOK | ECHOKE; /* Other bits in c_lflag: * XCASE Map uppercase to \lowercase [tried, doesn't work] * ECHONL Echo NL even if ECHO is not set * ECHOCTL Echo ctrl chars as ^c (else don't echo) - maybe set this? * ECHOPRT On erase, echo erased chars * [qwe input looks like "qwe\ewq/" on screen] * NOFLSH Don't flush input buffer after interrupt or quit chars * IEXTEN Enable extended functions (??) * [glibc says it enables c_cc[LNEXT] "enter literal char" * and c_cc[VDISCARD] "toggle discard buffered output" chars] * FLUSHO Output being flushed (c_cc[VDISCARD] is in effect) * PENDIN Retype pending input at next read or input char * (c_cc[VREPRINT] is being processed) * TOSTOP Send SIGTTOU for background output * (why "stty sane" unsets this bit?) */ G.tty_attrs.c_cc[VINTR] = CTL('C'); G.tty_attrs.c_cc[VQUIT] = CTL('\\'); G.tty_attrs.c_cc[VEOF] = CTL('D'); G.tty_attrs.c_cc[VEOL] = '\n'; #ifdef VSWTC G.tty_attrs.c_cc[VSWTC] = 0; #endif #ifdef VSWTCH G.tty_attrs.c_cc[VSWTCH] = 0; #endif G.tty_attrs.c_cc[VKILL] = CTL('U'); /* Other control chars: * VEOL2 * VERASE, VWERASE - (word) erase. we may set VERASE in get_logname * VREPRINT - reprint current input buffer * VLNEXT, VDISCARD, VSTATUS * VSUSP, VDSUSP - send (delayed) SIGTSTP * VSTART, VSTOP - chars used for IXON/IXOFF */ set_tty_attrs(); /* Now the newline character should be properly written */ full_write(STDOUT_FILENO, "\n", 1); } /* extract baud rate from modem status message */ static void auto_baud(void) { int nread; /* * This works only if the modem produces its status code AFTER raising * the DCD line, and if the computer is fast enough to set the proper * baud rate before the message has gone by. We expect a message of the * following format: * * * * The number is interpreted as the baud rate of the incoming call. If the * modem does not tell us the baud rate within one second, we will keep * using the current baud rate. It is advisable to enable BREAK * processing (comma-separated list of baud rates) if the processing of * modem status messages is enabled. */ G.tty_attrs.c_cc[VMIN] = 0; /* don't block reads (min read is 0 chars) */ set_tty_attrs(); /* * Wait for a while, then read everything the modem has said so far and * try to extract the speed of the dial-in call. */ sleep(1); nread = safe_read(STDIN_FILENO, G.line_buf, sizeof(G.line_buf) - 1); if (nread > 0) { int speed; char *bp; G.line_buf[nread] = '\0'; for (bp = G.line_buf; bp < G.line_buf + nread; bp++) { if (isdigit(*bp)) { speed = bcode(bp); if (speed > 0) cfsetspeed(&G.tty_attrs, speed); break; } } } /* Restore terminal settings */ G.tty_attrs.c_cc[VMIN] = 1; /* restore to value set by init_tty_attrs */ set_tty_attrs(); } /* get user name, establish parity, speed, erase, kill, eol; * return NULL on BREAK, logname on success */ static char *get_logname(void) { char *bp; char c; /* Flush pending input (esp. after parsing or switching the baud rate) */ usleep(100*1000); /* 0.1 sec */ tcflush(STDIN_FILENO, TCIFLUSH); /* Prompt for and read a login name */ do { /* Write issue file and prompt */ #ifdef ISSUE if (!(option_mask32 & F_NOISSUE)) print_login_issue(G.issue, G.tty_name); #endif print_login_prompt(); /* Read name, watch for break, erase, kill, end-of-line */ bp = G.line_buf; while (1) { /* Do not report trivial EINTR/EIO errors */ errno = EINTR; /* make read of 0 bytes be silent too */ if (read(STDIN_FILENO, &c, 1) < 1) { finalize_tty_attrs(); if (errno == EINTR || errno == EIO) exit(EXIT_SUCCESS); bb_perror_msg_and_die(bb_msg_read_error); } switch (c) { case '\r': case '\n': *bp = '\0'; G.eol = c; goto got_logname; case CTL('H'): case 0x7f: G.tty_attrs.c_cc[VERASE] = c; if (bp > G.line_buf) { full_write(STDOUT_FILENO, "\010 \010", 3); bp--; } break; case CTL('U'): while (bp > G.line_buf) { full_write(STDOUT_FILENO, "\010 \010", 3); bp--; } break; case CTL('C'): case CTL('D'): finalize_tty_attrs(); exit(EXIT_SUCCESS); case '\0': /* BREAK. If we have speeds to try, * return NULL (will switch speeds and return here) */ if (G.numspeed > 1) return NULL; /* fall through and ignore it */ default: if ((unsigned char)c < ' ') { /* ignore garbage characters */ } else if ((int)(bp - G.line_buf) < sizeof(G.line_buf) - 1) { /* echo and store the character */ full_write(STDOUT_FILENO, &c, 1); *bp++ = c; } break; } } /* end of get char loop */ got_logname: ; } while (G.line_buf[0] == '\0'); /* while logname is empty */ return G.line_buf; } static void alarm_handler(int sig UNUSED_PARAM) { finalize_tty_attrs(); _exit(EXIT_SUCCESS); } int getty_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int getty_main(int argc UNUSED_PARAM, char **argv) { int n; pid_t pid, tsid; char *logname; INIT_G(); G.login = _PATH_LOGIN; /* default login program */ #ifdef ISSUE G.issue = ISSUE; /* default issue file */ #endif G.eol = '\r'; /* Parse command-line arguments */ parse_args(argv); /* Create new session and pgrp, lose controlling tty */ pid = setsid(); /* this also gives us our pid :) */ if (pid < 0) { int fd; /* :( * docs/ctty.htm says: * "This is allowed only when the current process * is not a process group leader". * Thus, setsid() will fail if we _already_ are * a session leader - which is quite possible for getty! */ pid = getpid(); if (getsid(0) != pid) { //for debugging: //bb_perror_msg_and_die("setsid failed:" // " pid %d ppid %d" // " sid %d pgid %d", // pid, getppid(), // getsid(0), getpgid(0)); bb_perror_msg_and_die("setsid"); } /* Looks like we are already a session leader. * In this case (setsid failed) we may still have ctty, * and it may be different from tty we need to control! * If we still have ctty, on Linux ioctl(TIOCSCTTY) * (which we are going to use a bit later) always fails - * even if we try to take ctty which is already ours! * Try to drop old ctty now to prevent that. * Use O_NONBLOCK: old ctty may be a serial line. */ fd = open("/dev/tty", O_RDWR | O_NONBLOCK); if (fd >= 0) { /* TIOCNOTTY sends SIGHUP to the foreground * process group - which may include us! * Make sure to not die on it: */ sighandler_t old = signal(SIGHUP, SIG_IGN); ioctl(fd, TIOCNOTTY); close(fd); signal(SIGHUP, old); } } /* Close stdio, and stray descriptors, just in case */ n = xopen(bb_dev_null, O_RDWR); /* dup2(n, 0); - no, we need to handle "getty - 9600" too */ xdup2(n, 1); xdup2(n, 2); while (n > 2) close(n--); /* Logging. We want special flavor of error_msg_and_die */ die_sleep = 10; msg_eol = "\r\n"; /* most likely will internally use fd #3 in CLOEXEC mode: */ openlog(applet_name, LOG_PID, LOG_AUTH); logmode = LOGMODE_BOTH; #ifdef DEBUGGING dbf = xfopen_for_write(DEBUGTERM); for (n = 1; argv[n]; n++) { debug(argv[n]); debug("\n"); } #endif /* Open the tty as standard input, if it is not "-" */ debug("calling open_tty\n"); open_tty(); ndelay_off(STDIN_FILENO); debug("duping\n"); xdup2(STDIN_FILENO, 1); xdup2(STDIN_FILENO, 2); /* Steal ctty if we don't have it yet */ tsid = tcgetsid(STDIN_FILENO); if (tsid < 0 || pid != tsid) { if (ioctl(STDIN_FILENO, TIOCSCTTY, /*force:*/ (long)1) < 0) bb_perror_msg_and_die("TIOCSCTTY"); } #ifdef __linux__ /* Make ourself a foreground process group within our session */ if (tcsetpgrp(STDIN_FILENO, pid) < 0) bb_perror_msg_and_die("tcsetpgrp"); #endif /* * The following ioctl will fail if stdin is not a tty, but also when * there is noise on the modem control lines. In the latter case, the * common course of action is (1) fix your cables (2) give the modem more * time to properly reset after hanging up. SunOS users can achieve (2) * by patching the SunOS kernel variable "zsadtrlow" to a larger value; * 5 seconds seems to be a good value. */ if (tcgetattr(STDIN_FILENO, &G.tty_attrs) < 0) bb_perror_msg_and_die("tcgetattr"); /* Update the utmp file. This tty is ours now! */ update_utmp(pid, LOGIN_PROCESS, G.tty_name, "LOGIN", G.fakehost); /* Initialize tty attrs (raw mode, eight-bit, blocking i/o) */ debug("calling init_tty_attrs\n"); init_tty_attrs(G.speeds[0]); /* Write the modem init string and DON'T flush the buffers */ if (option_mask32 & F_INITSTRING) { debug("writing init string\n"); full_write1_str(G.initstring); } /* Optionally detect the baud rate from the modem status message */ debug("before autobaud\n"); if (option_mask32 & F_PARSE) auto_baud(); /* Set the optional timer */ signal(SIGALRM, alarm_handler); alarm(G.timeout); /* if 0, alarm is not set */ /* Optionally wait for CR or LF before writing /etc/issue */ if (option_mask32 & F_WAITCRLF) { char ch; debug("waiting for cr-lf\n"); while (safe_read(STDIN_FILENO, &ch, 1) == 1) { debug("read %x\n", (unsigned char)ch); if (ch == '\n' || ch == '\r') break; } } logname = NULL; if (!(option_mask32 & F_NOPROMPT)) { /* NB: init_tty_attrs already set line speed * to G.speeds[0] */ int baud_index = 0; while (1) { /* Read the login name */ debug("reading login name\n"); logname = get_logname(); if (logname) break; /* We are here only if G.numspeed > 1 */ baud_index = (baud_index + 1) % G.numspeed; cfsetspeed(&G.tty_attrs, G.speeds[baud_index]); set_tty_attrs(); } } /* Disable timer */ alarm(0); finalize_tty_attrs(); /* Let the login program take care of password validation */ /* We use PATH because we trust that root doesn't set "bad" PATH, * and getty is not suid-root applet */ /* With -n, logname == NULL, and login will ask for username instead */ BB_EXECLP(G.login, G.login, "--", logname, (char *)0); bb_error_msg_and_die("can't execute '%s'", G.login); }