| /* $OpenBSD: readpass.c,v 1.58 2019/11/27 05:00:17 djm Exp $ */ |
| /* |
| * Copyright (c) 2001 Markus Friedl. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #include "includes.h" |
| |
| #include <sys/types.h> |
| #include <sys/wait.h> |
| |
| #include <errno.h> |
| #include <fcntl.h> |
| #ifdef HAVE_PATHS_H |
| # include <paths.h> |
| #endif |
| #include <signal.h> |
| #include <stdarg.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <unistd.h> |
| |
| #include "xmalloc.h" |
| #include "misc.h" |
| #include "pathnames.h" |
| #include "log.h" |
| #include "ssh.h" |
| #include "uidswap.h" |
| |
| static char * |
| ssh_askpass(char *askpass, const char *msg) |
| { |
| pid_t pid, ret; |
| size_t len; |
| char *pass; |
| int p[2], status; |
| char buf[1024]; |
| void (*osigchld)(int); |
| |
| if (fflush(stdout) != 0) |
| error("ssh_askpass: fflush: %s", strerror(errno)); |
| if (askpass == NULL) |
| fatal("internal error: askpass undefined"); |
| if (pipe(p) == -1) { |
| error("ssh_askpass: pipe: %s", strerror(errno)); |
| return NULL; |
| } |
| osigchld = signal(SIGCHLD, SIG_DFL); |
| if ((pid = fork()) == -1) { |
| error("ssh_askpass: fork: %s", strerror(errno)); |
| signal(SIGCHLD, osigchld); |
| return NULL; |
| } |
| if (pid == 0) { |
| close(p[0]); |
| if (dup2(p[1], STDOUT_FILENO) == -1) |
| fatal("ssh_askpass: dup2: %s", strerror(errno)); |
| setenv("SSH_ASKPASS_PROMPT", "confirm", 1); /* hint to UI */ |
| execlp(askpass, askpass, msg, (char *)NULL); |
| fatal("ssh_askpass: exec(%s): %s", askpass, strerror(errno)); |
| } |
| close(p[1]); |
| |
| len = 0; |
| do { |
| ssize_t r = read(p[0], buf + len, sizeof(buf) - 1 - len); |
| |
| if (r == -1 && errno == EINTR) |
| continue; |
| if (r <= 0) |
| break; |
| len += r; |
| } while (sizeof(buf) - 1 - len > 0); |
| buf[len] = '\0'; |
| |
| close(p[0]); |
| while ((ret = waitpid(pid, &status, 0)) == -1) |
| if (errno != EINTR) |
| break; |
| signal(SIGCHLD, osigchld); |
| if (ret == -1 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) { |
| explicit_bzero(buf, sizeof(buf)); |
| return NULL; |
| } |
| |
| buf[strcspn(buf, "\r\n")] = '\0'; |
| pass = xstrdup(buf); |
| explicit_bzero(buf, sizeof(buf)); |
| return pass; |
| } |
| |
| /* |
| * Reads a passphrase from /dev/tty with echo turned off/on. Returns the |
| * passphrase (allocated with xmalloc). Exits if EOF is encountered. If |
| * RP_ALLOW_STDIN is set, the passphrase will be read from stdin if no |
| * tty is available |
| */ |
| char * |
| read_passphrase(const char *prompt, int flags) |
| { |
| char cr = '\r', *askpass = NULL, *ret, buf[1024]; |
| int rppflags, use_askpass = 0, ttyfd; |
| |
| rppflags = (flags & RP_ECHO) ? RPP_ECHO_ON : RPP_ECHO_OFF; |
| if (flags & RP_USE_ASKPASS) |
| use_askpass = 1; |
| else if (flags & RP_ALLOW_STDIN) { |
| if (!isatty(STDIN_FILENO)) { |
| debug("read_passphrase: stdin is not a tty"); |
| use_askpass = 1; |
| } |
| } else { |
| rppflags |= RPP_REQUIRE_TTY; |
| ttyfd = open(_PATH_TTY, O_RDWR); |
| if (ttyfd >= 0) { |
| /* |
| * If we're on a tty, ensure that show the prompt at |
| * the beginning of the line. This will hopefully |
| * clobber any password characters the user has |
| * optimistically typed before echo is disabled. |
| */ |
| (void)write(ttyfd, &cr, 1); |
| close(ttyfd); |
| } else { |
| debug("read_passphrase: can't open %s: %s", _PATH_TTY, |
| strerror(errno)); |
| use_askpass = 1; |
| } |
| } |
| |
| if ((flags & RP_USE_ASKPASS) && getenv("DISPLAY") == NULL) |
| return (flags & RP_ALLOW_EOF) ? NULL : xstrdup(""); |
| |
| if (use_askpass && getenv("DISPLAY")) { |
| if (getenv(SSH_ASKPASS_ENV)) |
| askpass = getenv(SSH_ASKPASS_ENV); |
| else |
| askpass = _PATH_SSH_ASKPASS_DEFAULT; |
| if ((ret = ssh_askpass(askpass, prompt)) == NULL) |
| if (!(flags & RP_ALLOW_EOF)) |
| return xstrdup(""); |
| return ret; |
| } |
| |
| if (readpassphrase(prompt, buf, sizeof buf, rppflags) == NULL) { |
| if (flags & RP_ALLOW_EOF) |
| return NULL; |
| return xstrdup(""); |
| } |
| |
| ret = xstrdup(buf); |
| explicit_bzero(buf, sizeof(buf)); |
| return ret; |
| } |
| |
| int |
| ask_permission(const char *fmt, ...) |
| { |
| va_list args; |
| char *p, prompt[1024]; |
| int allowed = 0; |
| |
| va_start(args, fmt); |
| vsnprintf(prompt, sizeof(prompt), fmt, args); |
| va_end(args); |
| |
| p = read_passphrase(prompt, RP_USE_ASKPASS|RP_ALLOW_EOF); |
| if (p != NULL) { |
| /* |
| * Accept empty responses and responses consisting |
| * of the word "yes" as affirmative. |
| */ |
| if (*p == '\0' || *p == '\n' || |
| strcasecmp(p, "yes") == 0) |
| allowed = 1; |
| free(p); |
| } |
| |
| return (allowed); |
| } |
| |
| struct notifier_ctx { |
| pid_t pid; |
| void (*osigchld)(int); |
| }; |
| |
| struct notifier_ctx * |
| notify_start(int force_askpass, const char *fmt, ...) |
| { |
| va_list args; |
| char *prompt = NULL; |
| int devnull; |
| pid_t pid; |
| void (*osigchld)(int); |
| const char *askpass; |
| struct notifier_ctx *ret; |
| |
| va_start(args, fmt); |
| xvasprintf(&prompt, fmt, args); |
| va_end(args); |
| |
| if (fflush(NULL) != 0) |
| error("%s: fflush: %s", __func__, strerror(errno)); |
| if (!force_askpass && isatty(STDERR_FILENO)) { |
| (void)write(STDERR_FILENO, "\r", 1); |
| (void)write(STDERR_FILENO, prompt, strlen(prompt)); |
| (void)write(STDERR_FILENO, "\r\n", 2); |
| free(prompt); |
| return NULL; |
| } |
| if ((askpass = getenv("SSH_ASKPASS")) == NULL) |
| askpass = _PATH_SSH_ASKPASS_DEFAULT; |
| if (getenv("DISPLAY") == NULL || *askpass == '\0') { |
| debug3("%s: cannot notify", __func__); |
| free(prompt); |
| return NULL; |
| } |
| osigchld = signal(SIGCHLD, SIG_DFL); |
| if ((pid = fork()) == -1) { |
| error("%s: fork: %s", __func__, strerror(errno)); |
| signal(SIGCHLD, osigchld); |
| free(prompt); |
| return NULL; |
| } |
| if (pid == 0) { |
| if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) |
| fatal("%s: open %s", __func__, strerror(errno)); |
| if (dup2(devnull, STDIN_FILENO) == -1 || |
| dup2(devnull, STDOUT_FILENO) == -1) |
| fatal("%s: dup2: %s", __func__, strerror(errno)); |
| closefrom(STDERR_FILENO + 1); |
| setenv("SSH_ASKPASS_PROMPT", "none", 1); /* hint to UI */ |
| execlp(askpass, askpass, prompt, (char *)NULL); |
| error("%s: exec(%s): %s", __func__, askpass, strerror(errno)); |
| _exit(1); |
| /* NOTREACHED */ |
| } |
| if ((ret = calloc(1, sizeof(*ret))) == NULL) { |
| kill(pid, SIGTERM); |
| fatal("%s: calloc failed", __func__); |
| } |
| ret->pid = pid; |
| ret->osigchld = osigchld; |
| free(prompt); |
| return ret; |
| } |
| |
| void |
| notify_complete(struct notifier_ctx *ctx) |
| { |
| int ret; |
| |
| if (ctx == NULL || ctx->pid <= 0) { |
| free(ctx); |
| return; |
| } |
| kill(ctx->pid, SIGTERM); |
| while ((ret = waitpid(ctx->pid, NULL, 0)) == -1) { |
| if (errno != EINTR) |
| break; |
| } |
| if (ret == -1) |
| fatal("%s: waitpid: %s", __func__, strerror(errno)); |
| signal(SIGCHLD, ctx->osigchld); |
| free(ctx); |
| } |