X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/054d8535f63d153f85667737017d42303176fc1e..f89c329410c18fe1f09d843747fad77babb9f89c:/unix/pty.c diff --git a/unix/pty.c b/unix/pty.c index 56d7d895..d99d4e50 100644 --- a/unix/pty.c +++ b/unix/pty.c @@ -1,11 +1,36 @@ +/* + * Pseudo-tty backend for pterm. + * + * Unlike the other backends, data for this one is not neatly + * encapsulated into a data structure, because it wouldn't make + * sense to do so - the utmp stuff has to be done before a backend + * is initialised, and starting a second pterm from the same + * process would therefore be infeasible because privileges would + * already have been dropped. Hence, I haven't bothered to keep the + * data dynamically allocated: instead, the backend handle is just + * a null pointer and ignored everywhere. + */ + #define _XOPEN_SOURCE -#include +#define _XOPEN_SOURCE_EXTENDED +#define _GNU_SOURCE #include #include #include #include +#include #include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include #include "putty.h" @@ -16,29 +41,185 @@ #define TRUE 1 #endif -int pty_master_fd; +#ifndef UTMP_FILE +#define UTMP_FILE "/var/run/utmp" +#endif +#ifndef WTMP_FILE +#define WTMP_FILE "/var/log/wtmp" +#endif +#ifndef LASTLOG_FILE +#ifdef _PATH_LASTLOG +#define LASTLOG_FILE _PATH_LASTLOG +#else +#define LASTLOG_FILE "/var/log/lastlog" +#endif +#endif + +/* + * Set up a default for vaguely sane systems. The idea is that if + * OMIT_UTMP is not defined, then at least one of the symbols which + * enable particular forms of utmp processing should be, if only so + * that a link error can warn you that you should have defined + * OMIT_UTMP if you didn't want any. Currently HAVE_PUTUTLINE is + * the only such symbol. + */ +#ifndef OMIT_UTMP +#if !defined HAVE_PUTUTLINE +#define HAVE_PUTUTLINE +#endif +#endif + +static Config pty_cfg; +static int pty_master_fd; +static void *pty_frontend; +static char pty_name[FILENAME_MAX]; +static int pty_signal_pipe[2]; +static int pty_child_pid; +static int pty_term_width, pty_term_height; +static int pty_child_dead, pty_finished; +static int pty_exit_code; +char **pty_argv; +int use_pty_argv = TRUE; + +static void pty_close(void); + +#ifndef OMIT_UTMP +static int pty_utmp_helper_pid, pty_utmp_helper_pipe; +static int pty_stamped_utmp = 0; +static struct utmp utmp_entry; + +static void setup_utmp(char *ttyname, char *location) +{ +#ifdef HAVE_LASTLOG + struct lastlog lastlog_entry; + FILE *lastlog; +#endif + struct passwd *pw; + FILE *wtmp; + time_t uttime; + + pw = getpwuid(getuid()); + memset(&utmp_entry, 0, sizeof(utmp_entry)); + utmp_entry.ut_type = USER_PROCESS; + utmp_entry.ut_pid = getpid(); + strncpy(utmp_entry.ut_line, ttyname+5, lenof(utmp_entry.ut_line)); + strncpy(utmp_entry.ut_id, ttyname+8, lenof(utmp_entry.ut_id)); + strncpy(utmp_entry.ut_user, pw->pw_name, lenof(utmp_entry.ut_user)); + strncpy(utmp_entry.ut_host, location, lenof(utmp_entry.ut_host)); + /* Apparently there are some architectures where (struct utmp).ut_time + * is not essentially time_t (e.g. Linux amd64). Hence the temporary. */ + time(&uttime); + utmp_entry.ut_time = uttime; /* may truncate */ + +#if defined HAVE_PUTUTLINE + utmpname(UTMP_FILE); + setutent(); + pututline(&utmp_entry); + endutent(); +#endif + + if ((wtmp = fopen(WTMP_FILE, "a")) != NULL) { + fwrite(&utmp_entry, 1, sizeof(utmp_entry), wtmp); + fclose(wtmp); + } + +#ifdef HAVE_LASTLOG + memset(&lastlog_entry, 0, sizeof(lastlog_entry)); + strncpy(lastlog_entry.ll_line, ttyname+5, lenof(lastlog_entry.ll_line)); + strncpy(lastlog_entry.ll_host, location, lenof(lastlog_entry.ll_host)); + time(&lastlog_entry.ll_time); + if ((lastlog = fopen(LASTLOG_FILE, "r+")) != NULL) { + fseek(lastlog, sizeof(lastlog_entry) * getuid(), SEEK_SET); + fwrite(&lastlog_entry, 1, sizeof(lastlog_entry), lastlog); + fclose(lastlog); + } +#endif + + pty_stamped_utmp = 1; -static void pty_size(void); +} -static void c_write(char *buf, int len) +static void cleanup_utmp(void) { - from_backend(0, buf, len); + FILE *wtmp; + time_t uttime; + + if (!pty_stamped_utmp) + return; + + utmp_entry.ut_type = DEAD_PROCESS; + memset(utmp_entry.ut_user, 0, lenof(utmp_entry.ut_user)); + time(&uttime); + utmp_entry.ut_time = uttime; + + if ((wtmp = fopen(WTMP_FILE, "a")) != NULL) { + fwrite(&utmp_entry, 1, sizeof(utmp_entry), wtmp); + fclose(wtmp); + } + + memset(utmp_entry.ut_line, 0, lenof(utmp_entry.ut_line)); + utmp_entry.ut_time = 0; + +#if defined HAVE_PUTUTLINE + utmpname(UTMP_FILE); + setutent(); + pututline(&utmp_entry); + endutent(); +#endif + + pty_stamped_utmp = 0; /* ensure we never double-cleanup */ } +#endif -/* - * Called to set up the pty. - * - * Returns an error message, or NULL on success. - * - * Also places the canonical host name into `realhost'. It must be - * freed by the caller. - */ -static char *pty_init(char *host, int port, char **realhost, int nodelay) +static void sigchld_handler(int signum) { - int slavefd; - char name[FILENAME_MAX]; - pid_t pid; + write(pty_signal_pipe[1], "x", 1); +} + +#ifndef OMIT_UTMP +static void fatal_sig_handler(int signum) +{ + putty_signal(signum, SIG_DFL); + cleanup_utmp(); + setuid(getuid()); + raise(signum); +} +#endif + +static void pty_open_master(void) +{ +#ifdef BSD_PTYS + const char chars1[] = "pqrstuvwxyz"; + const char chars2[] = "0123456789abcdef"; + const char *p1, *p2; + char master_name[20]; + struct group *gp; + + for (p1 = chars1; *p1; p1++) + for (p2 = chars2; *p2; p2++) { + sprintf(master_name, "/dev/pty%c%c", *p1, *p2); + pty_master_fd = open(master_name, O_RDWR); + if (pty_master_fd >= 0) { + if (geteuid() == 0 || + access(master_name, R_OK | W_OK) == 0) + goto got_one; + close(pty_master_fd); + } + } + /* If we get here, we couldn't get a tty at all. */ + fprintf(stderr, "pterm: unable to open a pseudo-terminal device\n"); + exit(1); + + got_one: + strcpy(pty_name, master_name); + pty_name[5] = 't'; /* /dev/ptyXX -> /dev/ttyXX */ + + /* We need to chown/chmod the /dev/ttyXX device. */ + gp = getgrnam("tty"); + chown(pty_name, getuid(), gp ? gp->gr_gid : -1); + chmod(pty_name, 0600); +#else pty_master_fd = open("/dev/ptmx", O_RDWR); if (pty_master_fd < 0) { @@ -56,14 +237,317 @@ static char *pty_init(char *host, int port, char **realhost, int nodelay) exit(1); } - name[FILENAME_MAX-1] = '\0'; - strncpy(name, ptsname(pty_master_fd), FILENAME_MAX-1); + pty_name[FILENAME_MAX-1] = '\0'; + strncpy(pty_name, ptsname(pty_master_fd), FILENAME_MAX-1); +#endif +} + +/* + * Pre-initialisation. This is here to get around the fact that GTK + * doesn't like being run in setuid/setgid programs (probably + * sensibly). So before we initialise GTK - and therefore before we + * even process the command line - we check to see if we're running + * set[ug]id. If so, we open our pty master _now_, chown it as + * necessary, and drop privileges. We can always close it again + * later. If we're potentially going to be doing utmp as well, we + * also fork off a utmp helper process and communicate with it by + * means of a pipe; the utmp helper will keep privileges in order + * to clean up utmp when we exit (i.e. when its end of our pipe + * closes). + */ +void pty_pre_init(void) +{ +#ifndef OMIT_UTMP + pid_t pid; + int pipefd[2]; +#endif + + /* set the child signal handler straight away; it needs to be set + * before we ever fork. */ + putty_signal(SIGCHLD, sigchld_handler); + pty_master_fd = -1; + + if (geteuid() != getuid() || getegid() != getgid()) { + pty_open_master(); + } + +#ifndef OMIT_UTMP + /* + * Fork off the utmp helper. + */ + if (pipe(pipefd) < 0) { + perror("pterm: pipe"); + exit(1); + } + pid = fork(); + if (pid < 0) { + perror("pterm: fork"); + exit(1); + } else if (pid == 0) { + char display[128], buffer[128]; + int dlen, ret; + + close(pipefd[1]); + /* + * Now sit here until we receive a display name from the + * other end of the pipe, and then stamp utmp. Unstamp utmp + * again, and exit, when the pipe closes. + */ + + dlen = 0; + while (1) { + + ret = read(pipefd[0], buffer, lenof(buffer)); + if (ret <= 0) { + cleanup_utmp(); + _exit(0); + } else if (!pty_stamped_utmp) { + if (dlen < lenof(display)) + memcpy(display+dlen, buffer, + min(ret, lenof(display)-dlen)); + if (buffer[ret-1] == '\0') { + /* + * Now we have a display name. NUL-terminate + * it, and stamp utmp. + */ + display[lenof(display)-1] = '\0'; + /* + * Trap as many fatal signals as we can in the + * hope of having the best possible chance to + * clean up utmp before termination. We are + * unfortunately unprotected against SIGKILL, + * but that's life. + */ + putty_signal(SIGHUP, fatal_sig_handler); + putty_signal(SIGINT, fatal_sig_handler); + putty_signal(SIGQUIT, fatal_sig_handler); + putty_signal(SIGILL, fatal_sig_handler); + putty_signal(SIGABRT, fatal_sig_handler); + putty_signal(SIGFPE, fatal_sig_handler); + putty_signal(SIGPIPE, fatal_sig_handler); + putty_signal(SIGALRM, fatal_sig_handler); + putty_signal(SIGTERM, fatal_sig_handler); + putty_signal(SIGSEGV, fatal_sig_handler); + putty_signal(SIGUSR1, fatal_sig_handler); + putty_signal(SIGUSR2, fatal_sig_handler); +#ifdef SIGBUS + putty_signal(SIGBUS, fatal_sig_handler); +#endif +#ifdef SIGPOLL + putty_signal(SIGPOLL, fatal_sig_handler); +#endif +#ifdef SIGPROF + putty_signal(SIGPROF, fatal_sig_handler); +#endif +#ifdef SIGSYS + putty_signal(SIGSYS, fatal_sig_handler); +#endif +#ifdef SIGTRAP + putty_signal(SIGTRAP, fatal_sig_handler); +#endif +#ifdef SIGVTALRM + putty_signal(SIGVTALRM, fatal_sig_handler); +#endif +#ifdef SIGXCPU + putty_signal(SIGXCPU, fatal_sig_handler); +#endif +#ifdef SIGXFSZ + putty_signal(SIGXFSZ, fatal_sig_handler); +#endif +#ifdef SIGIO + putty_signal(SIGIO, fatal_sig_handler); +#endif + setup_utmp(pty_name, display); + } + } + } + } else { + close(pipefd[0]); + pty_utmp_helper_pid = pid; + pty_utmp_helper_pipe = pipefd[1]; + } +#endif + + /* Drop privs. */ + { +#ifndef HAVE_NO_SETRESUID + int gid = getgid(), uid = getuid(); + int setresgid(gid_t, gid_t, gid_t); + int setresuid(uid_t, uid_t, uid_t); + setresgid(gid, gid, gid); + setresuid(uid, uid, uid); +#else + setgid(getgid()); + setuid(getuid()); +#endif + } +} + +int pty_select_result(int fd, int event) +{ + char buf[4096]; + int ret; + int finished = FALSE; + + if (fd == pty_master_fd && event == 1) { + + ret = read(pty_master_fd, buf, sizeof(buf)); + + /* + * Clean termination condition is that either ret == 0, or ret + * < 0 and errno == EIO. Not sure why the latter, but it seems + * to happen. Boo. + */ + if (ret == 0 || (ret < 0 && errno == EIO)) { + /* + * We assume a clean exit if the pty has closed but the + * actual child process hasn't. The only way I can + * imagine this happening is if it detaches itself from + * the pty and goes daemonic - in which case the + * expected usage model would precisely _not_ be for + * the pterm window to hang around! + */ + finished = TRUE; + if (!pty_child_dead) + pty_exit_code = 0; + } else if (ret < 0) { + perror("read pty master"); + exit(1); + } else if (ret > 0) { + from_backend(pty_frontend, 0, buf, ret); + } + } else if (fd == pty_signal_pipe[0]) { + pid_t pid; + int status; + char c[1]; + + read(pty_signal_pipe[0], c, 1); /* ignore its value; it'll be `x' */ + + do { + pid = waitpid(-1, &status, WNOHANG); + if (pid == pty_child_pid && + (WIFEXITED(status) || WIFSIGNALED(status))) { + /* + * The primary child process died. We could keep + * the terminal open for remaining subprocesses to + * output to, but conventional wisdom seems to feel + * that that's the Wrong Thing for an xterm-alike, + * so we bail out now (though we don't necessarily + * _close_ the window, depending on the state of + * Close On Exit). This would be easy enough to + * change or make configurable if necessary. + */ + pty_exit_code = status; + pty_child_dead = TRUE; + finished = TRUE; + } + } while(pid > 0); + } + + if (finished && !pty_finished) { + uxsel_del(pty_master_fd); + pty_close(); + pty_master_fd = -1; + + pty_finished = TRUE; + + /* + * This is a slight layering-violation sort of hack: only + * if we're not closing on exit (COE is set to Never, or to + * Only On Clean and it wasn't a clean exit) do we output a + * `terminated' message. + */ + if (pty_cfg.close_on_exit == FORCE_OFF || + (pty_cfg.close_on_exit == AUTO && pty_exit_code != 0)) { + char message[512]; + if (WIFEXITED(pty_exit_code)) + sprintf(message, "\r\n[pterm: process terminated with exit" + " code %d]\r\n", WEXITSTATUS(pty_exit_code)); + else if (WIFSIGNALED(pty_exit_code)) +#ifdef HAVE_NO_STRSIGNAL + sprintf(message, "\r\n[pterm: process terminated on signal" + " %d]\r\n", WTERMSIG(pty_exit_code)); +#else + sprintf(message, "\r\n[pterm: process terminated on signal" + " %d (%.400s)]\r\n", WTERMSIG(pty_exit_code), + strsignal(WTERMSIG(pty_exit_code))); +#endif + from_backend(pty_frontend, 0, message, strlen(message)); + } + + notify_remote_exit(pty_frontend); + } + return !finished; +} + +static void pty_uxsel_setup(void) +{ + uxsel_set(pty_master_fd, 1, pty_select_result); + uxsel_set(pty_signal_pipe[0], 1, pty_select_result); +} + +/* + * Called to set up the pty. + * + * Returns an error message, or NULL on success. + * + * Also places the canonical host name into `realhost'. It must be + * freed by the caller. + */ +static const char *pty_init(void *frontend, void **backend_handle, Config *cfg, + char *host, int port, char **realhost, int nodelay, + int keepalive) +{ + int slavefd; + pid_t pid, pgrp; + long windowid; + + pty_frontend = frontend; + *backend_handle = NULL; /* we can't sensibly use this, sadly */ + + pty_cfg = *cfg; /* structure copy */ + pty_term_width = cfg->width; + pty_term_height = cfg->height; + + if (pty_master_fd < 0) + pty_open_master(); - slavefd = open(name, O_RDWR); - if (slavefd < 0) { - perror("slave pty: open"); - return 1; + /* + * Set the backspace character to be whichever of ^H and ^? is + * specified by bksp_is_delete. + */ + { + struct termios attrs; + tcgetattr(pty_master_fd, &attrs); + attrs.c_cc[VERASE] = cfg->bksp_is_delete ? '\177' : '\010'; + tcsetattr(pty_master_fd, TCSANOW, &attrs); + } + +#ifndef OMIT_UTMP + /* + * Stamp utmp (that is, tell the utmp helper process to do so), + * or not. + */ + if (!cfg->stamp_utmp) { + close(pty_utmp_helper_pipe); /* just let the child process die */ + pty_utmp_helper_pipe = -1; + } else { + char *location = get_x_display(pty_frontend); + int len = strlen(location)+1, pos = 0; /* +1 to include NUL */ + while (pos < len) { + int ret = write(pty_utmp_helper_pipe, location+pos, len - pos); + if (ret < 0) { + perror("pterm: writing to utmp helper process"); + close(pty_utmp_helper_pipe); /* arrgh, just give up */ + pty_utmp_helper_pipe = -1; + break; + } + pos += ret; + } } +#endif + + windowid = get_windowid(pty_frontend); /* * Fork and execute the command. @@ -71,7 +555,7 @@ static char *pty_init(char *host, int port, char **realhost, int nodelay) pid = fork(); if (pid < 0) { perror("fork"); - return 1; + exit(1); } if (pid == 0) { @@ -79,38 +563,131 @@ static char *pty_init(char *host, int port, char **realhost, int nodelay) /* * We are the child. */ + + slavefd = open(pty_name, O_RDWR); + if (slavefd < 0) { + perror("slave pty: open"); + _exit(1); + } + close(pty_master_fd); - close(0); - close(1); - close(2); fcntl(slavefd, F_SETFD, 0); /* don't close on exec */ dup2(slavefd, 0); dup2(slavefd, 1); dup2(slavefd, 2); setsid(); - setpgrp(); - tcsetpgrp(0, getpgrp()); + ioctl(slavefd, TIOCSCTTY, 1); + pgrp = getpid(); + tcsetpgrp(slavefd, pgrp); + setpgid(pgrp, pgrp); + close(open(pty_name, O_WRONLY, 0)); + setpgid(pgrp, pgrp); /* Close everything _else_, for tidiness. */ for (i = 3; i < 1024; i++) close(i); - execl(getenv("SHELL"), getenv("SHELL"), NULL); + { + char term_env_var[10 + sizeof(cfg->termtype)]; + sprintf(term_env_var, "TERM=%s", cfg->termtype); + putenv(term_env_var); + } + { + char windowid_env_var[40]; + sprintf(windowid_env_var, "WINDOWID=%ld", windowid); + putenv(windowid_env_var); + } + { + char *e = cfg->environmt; + char *var, *varend, *val, *varval; + while (*e) { + var = e; + while (*e && *e != '\t') e++; + varend = e; + if (*e == '\t') e++; + val = e; + while (*e) e++; + e++; + + varval = dupprintf("%.*s=%s", varend-var, var, val); + putenv(varval); + /* + * We must not free varval, since putenv links it + * into the environment _in place_. Weird, but + * there we go. Memory usage will be rationalised + * as soon as we exec anyway. + */ + } + } + + /* + * SIGINT and SIGQUIT may have been set to ignored by our + * parent, particularly by things like sh -c 'pterm &' and + * some window managers. SIGCHLD, meanwhile, was blocked + * during pt_main() startup. Reverse all this for our child + * process. + */ + putty_signal(SIGINT, SIG_DFL); + putty_signal(SIGQUIT, SIG_DFL); + block_signal(SIGCHLD, 0); + if (pty_argv) + execvp(pty_argv[0], pty_argv); + else { + char *shell = getenv("SHELL"); + char *shellname; + if (cfg->login_shell) { + char *p = strrchr(shell, '/'); + shellname = snewn(2+strlen(shell), char); + p = p ? p+1 : shell; + sprintf(shellname, "-%s", p); + } else + shellname = shell; + execl(getenv("SHELL"), shellname, NULL); + } + /* * If we're here, exec has gone badly foom. */ perror("exec"); - exit(127); + _exit(127); } else { - close(slavefd); + pty_child_pid = pid; + pty_child_dead = FALSE; + pty_finished = FALSE; + } + + if (pipe(pty_signal_pipe) < 0) { + perror("pipe"); + exit(1); } + pty_uxsel_setup(); return NULL; } +static void pty_reconfig(void *handle, Config *cfg) +{ + /* + * We don't have much need to reconfigure this backend, but + * unfortunately we do need to pick up the setting of Close On + * Exit so we know whether to give a `terminated' message. + */ + pty_cfg = *cfg; /* structure copy */ +} + +/* + * Stub routine (never called in pterm). + */ +static void pty_free(void *handle) +{ +} + /* * Called to send data down the pty. */ -static int pty_send(char *buf, int len) +static int pty_send(void *handle, char *buf, int len) { + if (pty_master_fd < 0) + return 0; /* ignore all writes if fd closed */ + while (len > 0) { int ret = write(pty_master_fd, buf, len); if (ret < 0) { @@ -123,10 +700,24 @@ static int pty_send(char *buf, int len) return 0; } +static void pty_close(void) +{ + if (pty_master_fd >= 0) { + close(pty_master_fd); + pty_master_fd = -1; + } +#ifndef OMIT_UTMP + if (pty_utmp_helper_pipe >= 0) { + close(pty_utmp_helper_pipe); /* this causes utmp to be cleaned up */ + pty_utmp_helper_pipe = -1; + } +#endif +} + /* * Called to query the current socket sendability status. */ -static int pty_sendbuffer(void) +static int pty_sendbuffer(void *handle) { return 0; } @@ -134,57 +725,106 @@ static int pty_sendbuffer(void) /* * Called to set the size of the window */ -static void pty_size(void) +static void pty_size(void *handle, int width, int height) { - /* FIXME: will need to do TIOCSWINSZ or whatever. */ + struct winsize size; + + pty_term_width = width; + pty_term_height = height; + + size.ws_row = (unsigned short)pty_term_height; + size.ws_col = (unsigned short)pty_term_width; + size.ws_xpixel = (unsigned short) pty_term_width * + font_dimension(pty_frontend, 0); + size.ws_ypixel = (unsigned short) pty_term_height * + font_dimension(pty_frontend, 1); + ioctl(pty_master_fd, TIOCSWINSZ, (void *)&size); return; } /* * Send special codes. */ -static void pty_special(Telnet_Special code) +static void pty_special(void *handle, Telnet_Special code) { /* Do nothing! */ return; } -static Socket pty_socket(void) +/* + * Return a list of the special codes that make sense in this + * protocol. + */ +static const struct telnet_special *pty_get_specials(void *handle) +{ + /* + * Hmm. When I get round to having this actually usable, it + * might be quite nice to have the ability to deliver a few + * well chosen signals to the child process - SIGINT, SIGTERM, + * SIGKILL at least. + */ + return NULL; +} + +static Socket pty_socket(void *handle) { return NULL; /* shouldn't ever be needed */ } -static int pty_sendok(void) +static int pty_sendok(void *handle) { return 1; } -static void pty_unthrottle(int backlog) +static void pty_unthrottle(void *handle, int backlog) { /* do nothing */ } -static int pty_ldisc(int option) +static int pty_ldisc(void *handle, int option) { return 0; /* neither editing nor echoing */ } -static int pty_exitcode(void) +static void pty_provide_ldisc(void *handle, void *ldisc) +{ + /* This is a stub. */ +} + +static void pty_provide_logctx(void *handle, void *logctx) +{ + /* This is a stub. */ +} + +static int pty_exitcode(void *handle) +{ + if (!pty_finished) + return -1; /* not dead yet */ + else + return pty_exit_code; +} + +static int pty_cfg_info(void *handle) { - /* Shouldn't ever be required */ return 0; } Backend pty_backend = { pty_init, + pty_free, + pty_reconfig, pty_send, pty_sendbuffer, pty_size, pty_special, + pty_get_specials, pty_socket, pty_exitcode, pty_sendok, pty_ldisc, + pty_provide_ldisc, + pty_provide_logctx, pty_unthrottle, + pty_cfg_info, 1 };