X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/1709795fee167cc2d2d423df0161e7963376b910..b9d7bcadee831e9b59fb785f2464a5fc1897bd1a:/unix/pty.c diff --git a/unix/pty.c b/unix/pty.c index 291247ee..67addceb 100644 --- a/unix/pty.c +++ b/unix/pty.c @@ -1,5 +1,34 @@ +/* + * 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 +#define _XOPEN_SOURCE_EXTENDED +#include + #include #include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include #include "putty.h" @@ -10,11 +39,339 @@ #define TRUE 1 #endif -static void pty_size(void); +#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 -static void c_write(char *buf, int len) +/* + * 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 + +int pty_master_fd; +static char pty_name[FILENAME_MAX]; +static int pty_stamped_utmp = 0; +static int pty_child_pid; +static int pty_utmp_helper_pid, pty_utmp_helper_pipe; +static int pty_term_width, pty_term_height; +static sig_atomic_t pty_child_dead; +static int pty_exit_code; +#ifndef OMIT_UTMP +static struct utmp utmp_entry; +#endif +char **pty_argv; + +static void setup_utmp(char *ttyname, char *location) { - from_backend(0, buf, len); +#ifndef OMIT_UTMP +#ifdef HAVE_LASTLOG + struct lastlog lastlog_entry; + FILE *lastlog; +#endif + struct passwd *pw; + FILE *wtmp; + + 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)); + time(&utmp_entry.ut_time); + +#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; + +#endif +} + +static void cleanup_utmp(void) +{ +#ifndef OMIT_UTMP + FILE *wtmp; + + if (!pty_stamped_utmp) + return; + + utmp_entry.ut_type = DEAD_PROCESS; + memset(utmp_entry.ut_user, 0, lenof(utmp_entry.ut_user)); + time(&utmp_entry.ut_time); + + 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 +} + +static void sigchld_handler(int signum) +{ + pid_t pid; + int status; + pid = waitpid(-1, &status, WNOHANG); + if (pid == pty_child_pid && (WIFEXITED(status) || WIFSIGNALED(status))) { + pty_exit_code = status; + pty_child_dead = TRUE; + } +} + +static void fatal_sig_handler(int signum) +{ + signal(signum, SIG_DFL); + cleanup_utmp(); + setuid(getuid()); + raise(signum); +} + +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) { + perror("/dev/ptmx: open"); + exit(1); + } + + if (grantpt(pty_master_fd) < 0) { + perror("grantpt"); + exit(1); + } + + if (unlockpt(pty_master_fd) < 0) { + perror("unlockpt"); + exit(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) +{ + pid_t pid; + int pipefd[2]; + + 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. + */ + signal(SIGHUP, fatal_sig_handler); + signal(SIGINT, fatal_sig_handler); + signal(SIGQUIT, fatal_sig_handler); + signal(SIGILL, fatal_sig_handler); + signal(SIGABRT, fatal_sig_handler); + signal(SIGFPE, fatal_sig_handler); + signal(SIGPIPE, fatal_sig_handler); + signal(SIGALRM, fatal_sig_handler); + signal(SIGTERM, fatal_sig_handler); + signal(SIGSEGV, fatal_sig_handler); + signal(SIGUSR1, fatal_sig_handler); + signal(SIGUSR2, fatal_sig_handler); +#ifdef SIGBUS + signal(SIGBUS, fatal_sig_handler); +#endif +#ifdef SIGPOLL + signal(SIGPOLL, fatal_sig_handler); +#endif +#ifdef SIGPROF + signal(SIGPROF, fatal_sig_handler); +#endif +#ifdef SIGSYS + signal(SIGSYS, fatal_sig_handler); +#endif +#ifdef SIGTRAP + signal(SIGTRAP, fatal_sig_handler); +#endif +#ifdef SIGVTALRM + signal(SIGVTALRM, fatal_sig_handler); +#endif +#ifdef SIGXCPU + signal(SIGXCPU, fatal_sig_handler); +#endif +#ifdef SIGXFSZ + signal(SIGXFSZ, fatal_sig_handler); +#endif +#ifdef SIGIO + signal(SIGIO, fatal_sig_handler); +#endif + /* Also clean up utmp on normal exit. */ + atexit(cleanup_utmp); + setup_utmp(pty_name, display); + } + } + } + } else { + close(pipefd[0]); + pty_utmp_helper_pid = pid; + pty_utmp_helper_pipe = pipefd[1]; + signal(SIGCHLD, sigchld_handler); + } +#endif + + /* Drop privs. */ + { + int gid = getgid(), uid = getuid(); +#ifndef HAVE_NO_SETRESUID + 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 + } } /* @@ -25,25 +382,162 @@ static void c_write(char *buf, int len) * 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 char *pty_init(void *frontend, void **backend_handle, + char *host, int port, char **realhost, int nodelay) { - /* FIXME: do nothing for now */ + int slavefd; + pid_t pid, pgrp; + + *backend_handle = NULL; /* we can't sensibly use this, sadly */ + + pty_term_width = cfg.width; + pty_term_height = cfg.height; + + if (pty_master_fd < 0) + pty_open_master(); + + /* + * 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); + } + + /* + * 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 */ + else { + char *location = get_x_display(); + 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 */ + break; + } + pos += ret; + } + } + + /* + * Fork and execute the command. + */ + pid = fork(); + if (pid < 0) { + perror("fork"); + exit(1); + } + + if (pid == 0) { + int i; + /* + * We are the child. + */ + + slavefd = open(pty_name, O_RDWR); + if (slavefd < 0) { + perror("slave pty: open"); + exit(1); + } + + close(pty_master_fd); + fcntl(slavefd, F_SETFD, 0); /* don't close on exec */ + dup2(slavefd, 0); + dup2(slavefd, 1); + dup2(slavefd, 2); + setsid(); + ioctl(slavefd, TIOCSCTTY, 1); + pgrp = getpid(); + tcsetpgrp(slavefd, pgrp); + setpgrp(); + close(open(pty_name, O_WRONLY, 0)); + setpgrp(); + /* Close everything _else_, for tidiness. */ + for (i = 3; i < 1024; i++) + close(i); + { + char term_env_var[10 + sizeof(cfg.termtype)]; + sprintf(term_env_var, "TERM=%s", cfg.termtype); + putenv(term_env_var); + } + /* + * SIGINT and SIGQUIT may have been set to ignored by our + * parent, particularly by things like sh -c 'pterm &' and + * some window managers. Reverse this for our child process. + */ + signal(SIGINT, SIG_DFL); + signal(SIGQUIT, SIG_DFL); + 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 = smalloc(2+strlen(shell)); + 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); + } else { + close(slavefd); + pty_child_pid = pid; + pty_child_dead = FALSE; + signal(SIGCHLD, sigchld_handler); + } + return NULL; } /* * 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) { - c_write(buf, len); /* FIXME: diagnostic thingy */ + 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) { + perror("write pty master"); + exit(1); + } + buf += ret; + len -= ret; + } return 0; } +void pty_close(void) +{ + if (pty_master_fd >= 0) { + close(pty_master_fd); + pty_master_fd = -1; + } + close(pty_utmp_helper_pipe); /* this causes utmp to be cleaned up */ +} + /* * Called to query the current socket sendability status. */ -static int pty_sendbuffer(void) +static int pty_sendbuffer(void *handle) { return 0; } @@ -51,45 +545,61 @@ 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(0); + size.ws_ypixel = (unsigned short) pty_term_height * font_dimension(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) +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) { - /* Shouldn't ever be required */ - return 0; + /* This is a stub. */ +} + +static int pty_exitcode(void *handle) +{ + if (!pty_child_dead) + return -1; /* not dead yet */ + else + return pty_exit_code; } Backend pty_backend = { @@ -102,6 +612,7 @@ Backend pty_backend = { pty_exitcode, pty_sendok, pty_ldisc, + pty_provide_ldisc, pty_unthrottle, 1 };