X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/755a6d84a307a02fefb7c6f3d8d9cbc41da4e92a..86916870d36cb70e7ef0ea760e75a6ae8b2d83a5:/unix/pty.c diff --git a/unix/pty.c b/unix/pty.c index 8edbe484..1c213e86 100644 --- a/unix/pty.c +++ b/unix/pty.c @@ -1,3 +1,16 @@ +/* + * 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 @@ -16,6 +29,7 @@ #include #include #include +#include #include "putty.h" @@ -40,22 +54,35 @@ #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 + int pty_master_fd; +static void *pty_frontend; +static char pty_name[FILENAME_MAX]; +static int pty_stamped_utmp = 0; static int pty_child_pid; -static sig_atomic_t pty_child_dead; +static int pty_utmp_helper_pid, pty_utmp_helper_pipe; +static int pty_term_width, pty_term_height; +static volatile sig_atomic_t pty_child_dead; +static volatile int pty_exit_code; #ifndef OMIT_UTMP static struct utmp utmp_entry; #endif char **pty_argv; -int pty_child_is_dead(void) -{ - return pty_child_dead; -} - -static void pty_size(void); - -static void setup_utmp(char *ttyname) +static void setup_utmp(char *ttyname, char *location) { #ifndef OMIT_UTMP #ifdef HAVE_LASTLOG @@ -63,7 +90,6 @@ static void setup_utmp(char *ttyname) FILE *lastlog; #endif struct passwd *pw; - char *location = get_x_display(); FILE *wtmp; pw = getpwuid(getuid()); @@ -100,6 +126,8 @@ static void setup_utmp(char *ttyname) } #endif + pty_stamped_utmp = 1; + #endif } @@ -108,6 +136,9 @@ 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); @@ -127,67 +158,67 @@ static void cleanup_utmp(void) endutent(); #endif + pty_stamped_utmp = 0; /* ensure we never double-cleanup */ #endif } static void sigchld_handler(int signum) { + int save_errno = errno; pid_t pid; int status; - pid = waitpid(-1, &status, WNOHANG); - if (pid == pty_child_pid && (WIFEXITED(status) || WIFSIGNALED(status))) - pty_child_dead = TRUE; + + do { + pid = waitpid(-1, &status, WNOHANG); + if (pid == pty_child_pid && (WIFEXITED(status) || WIFSIGNALED(status))) { + pty_exit_code = status; + pty_child_dead = TRUE; + } + } while(pid > 0); + errno = save_errno; } static void fatal_sig_handler(int signum) { - signal(signum, SIG_DFL); + putty_signal(signum, SIG_DFL); cleanup_utmp(); setuid(getuid()); raise(signum); } -/* - * 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 pty_open_master(void) { - int slavefd; - char name[FILENAME_MAX]; - pid_t pid, pgrp; - #ifdef BSD_PTYS - { - const char chars1[] = "pqrstuvwxyz"; - const char chars2[] = "0123456789abcdef"; - const char *p1, *p2; - char master_name[20]; - - 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); - } + 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); + /* 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(name, master_name); - name[5] = 't'; /* /dev/ptyXX -> /dev/ttyXX */ - } + 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); @@ -206,56 +237,203 @@ 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) +{ + pid_t pid; + int pipefd[2]; + + /* 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 /* - * Trap as many fatal signals as we can in the hope of having - * the best chance to clean up utmp before termination. + * Fork off the utmp helper. */ - 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); + 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 - signal(SIGBUS, fatal_sig_handler); + putty_signal(SIGBUS, fatal_sig_handler); #endif #ifdef SIGPOLL - signal(SIGPOLL, fatal_sig_handler); + putty_signal(SIGPOLL, fatal_sig_handler); #endif #ifdef SIGPROF - signal(SIGPROF, fatal_sig_handler); + putty_signal(SIGPROF, fatal_sig_handler); #endif #ifdef SIGSYS - signal(SIGSYS, fatal_sig_handler); + putty_signal(SIGSYS, fatal_sig_handler); #endif #ifdef SIGTRAP - signal(SIGTRAP, fatal_sig_handler); + putty_signal(SIGTRAP, fatal_sig_handler); #endif #ifdef SIGVTALRM - signal(SIGVTALRM, fatal_sig_handler); + putty_signal(SIGVTALRM, fatal_sig_handler); #endif #ifdef SIGXCPU - signal(SIGXCPU, fatal_sig_handler); + putty_signal(SIGXCPU, fatal_sig_handler); #endif #ifdef SIGXFSZ - signal(SIGXFSZ, fatal_sig_handler); + putty_signal(SIGXFSZ, fatal_sig_handler); #endif #ifdef SIGIO - signal(SIGIO, fatal_sig_handler); + 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. */ + { + 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 - /* Also clean up utmp on normal exit. */ - atexit(cleanup_utmp); - setup_utmp(name); + } +} + +/* + * 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(void *frontend, void **backend_handle, Config *cfg, + char *host, int port, char **realhost, int nodelay) +{ + int slavefd; + pid_t pid, pgrp; + + pty_frontend = frontend; + *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(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 */ + break; + } + pos += ret; + } + } /* * Fork and execute the command. @@ -272,25 +450,13 @@ static char *pty_init(char *host, int port, char **realhost, int nodelay) * We are the child. */ - slavefd = open(name, O_RDWR); + slavefd = open(pty_name, O_RDWR); if (slavefd < 0) { perror("slave pty: open"); - exit(1); + _exit(1); } -#ifdef BSD_PTYS - /* We need to chown/chmod the /dev/ttyXX device. */ - { - struct group *gp = getgrnam("tty"); - fchown(slavefd, getuid(), gp ? gp->gr_gid : -1); - fchmod(slavefd, 0600); - } -#endif - 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); @@ -300,43 +466,66 @@ static char *pty_init(char *host, int port, char **realhost, int nodelay) pgrp = getpid(); tcsetpgrp(slavefd, pgrp); setpgrp(); - close(open(name, O_WRONLY, 0)); + close(open(pty_name, O_WRONLY, 0)); setpgrp(); - /* In case we were setgid-utmp or setuid-root, drop privs. */ - setgid(getgid()); - setuid(getuid()); /* 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); + 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. + */ + putty_signal(SIGINT, SIG_DFL); + putty_signal(SIGQUIT, SIG_DFL); if (pty_argv) execvp(pty_argv[0], pty_argv); - else - execl(getenv("SHELL"), getenv("SHELL"), NULL); + 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); + _exit(127); } else { - close(slavefd); pty_child_pid = pid; pty_child_dead = FALSE; - signal(SIGCHLD, sigchld_handler); - } + } return NULL; } /* + * Stub routine (we don't have any need to reconfigure this backend). + */ +static void pty_reconfig(void *handle, Config *cfg) +{ +} + +/* * 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) { @@ -349,10 +538,19 @@ static int pty_send(char *buf, int len) 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; } @@ -360,12 +558,19 @@ 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) { struct winsize size; - size.ws_row = (unsigned short)rows; - size.ws_col = (unsigned short)cols; + 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; } @@ -373,40 +578,53 @@ static void pty_size(void) /* * 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 void pty_provide_logctx(void *handle, void *logctx) +{ + /* 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 = { pty_init, + pty_reconfig, pty_send, pty_sendbuffer, pty_size, @@ -415,6 +633,8 @@ Backend pty_backend = { pty_exitcode, pty_sendok, pty_ldisc, + pty_provide_ldisc, + pty_provide_logctx, pty_unthrottle, 1 };