Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame^] | 1 | /* $OpenBSD: readpass.c,v 1.50 2014/02/02 03:44:31 djm Exp $ */ |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 2 | /* |
| 3 | * Copyright (c) 2001 Markus Friedl. All rights reserved. |
| 4 | * |
| 5 | * Redistribution and use in source and binary forms, with or without |
| 6 | * modification, are permitted provided that the following conditions |
| 7 | * are met: |
| 8 | * 1. Redistributions of source code must retain the above copyright |
| 9 | * notice, this list of conditions and the following disclaimer. |
| 10 | * 2. Redistributions in binary form must reproduce the above copyright |
| 11 | * notice, this list of conditions and the following disclaimer in the |
| 12 | * documentation and/or other materials provided with the distribution. |
| 13 | * |
| 14 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| 15 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 16 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| 17 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 18 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 19 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 20 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 21 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 22 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| 23 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 24 | */ |
| 25 | |
| 26 | #include "includes.h" |
| 27 | |
| 28 | #include <sys/types.h> |
| 29 | #include <sys/wait.h> |
| 30 | |
| 31 | #include <errno.h> |
| 32 | #include <fcntl.h> |
| 33 | #ifdef HAVE_PATHS_H |
| 34 | # include <paths.h> |
| 35 | #endif |
| 36 | #include <signal.h> |
| 37 | #include <stdarg.h> |
| 38 | #include <stdio.h> |
| 39 | #include <stdlib.h> |
| 40 | #include <string.h> |
| 41 | #include <unistd.h> |
| 42 | |
| 43 | #include "xmalloc.h" |
| 44 | #include "misc.h" |
| 45 | #include "pathnames.h" |
| 46 | #include "log.h" |
| 47 | #include "ssh.h" |
| 48 | #include "uidswap.h" |
| 49 | |
| 50 | static char * |
| 51 | ssh_askpass(char *askpass, const char *msg) |
| 52 | { |
| 53 | pid_t pid, ret; |
| 54 | size_t len; |
| 55 | char *pass; |
| 56 | int p[2], status; |
| 57 | char buf[1024]; |
| 58 | void (*osigchld)(int); |
| 59 | |
| 60 | if (fflush(stdout) != 0) |
| 61 | error("ssh_askpass: fflush: %s", strerror(errno)); |
| 62 | if (askpass == NULL) |
| 63 | fatal("internal error: askpass undefined"); |
| 64 | if (pipe(p) < 0) { |
| 65 | error("ssh_askpass: pipe: %s", strerror(errno)); |
| 66 | return NULL; |
| 67 | } |
| 68 | osigchld = signal(SIGCHLD, SIG_DFL); |
| 69 | if ((pid = fork()) < 0) { |
| 70 | error("ssh_askpass: fork: %s", strerror(errno)); |
| 71 | signal(SIGCHLD, osigchld); |
| 72 | return NULL; |
| 73 | } |
| 74 | if (pid == 0) { |
| 75 | permanently_drop_suid(getuid()); |
| 76 | close(p[0]); |
| 77 | if (dup2(p[1], STDOUT_FILENO) < 0) |
| 78 | fatal("ssh_askpass: dup2: %s", strerror(errno)); |
| 79 | execlp(askpass, askpass, msg, (char *) 0); |
| 80 | fatal("ssh_askpass: exec(%s): %s", askpass, strerror(errno)); |
| 81 | } |
| 82 | close(p[1]); |
| 83 | |
| 84 | len = 0; |
| 85 | do { |
| 86 | ssize_t r = read(p[0], buf + len, sizeof(buf) - 1 - len); |
| 87 | |
| 88 | if (r == -1 && errno == EINTR) |
| 89 | continue; |
| 90 | if (r <= 0) |
| 91 | break; |
| 92 | len += r; |
| 93 | } while (sizeof(buf) - 1 - len > 0); |
| 94 | buf[len] = '\0'; |
| 95 | |
| 96 | close(p[0]); |
| 97 | while ((ret = waitpid(pid, &status, 0)) < 0) |
| 98 | if (errno != EINTR) |
| 99 | break; |
| 100 | signal(SIGCHLD, osigchld); |
| 101 | if (ret == -1 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) { |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame^] | 102 | explicit_bzero(buf, sizeof(buf)); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 103 | return NULL; |
| 104 | } |
| 105 | |
| 106 | buf[strcspn(buf, "\r\n")] = '\0'; |
| 107 | pass = xstrdup(buf); |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame^] | 108 | explicit_bzero(buf, sizeof(buf)); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 109 | return pass; |
| 110 | } |
| 111 | |
| 112 | /* |
| 113 | * Reads a passphrase from /dev/tty with echo turned off/on. Returns the |
| 114 | * passphrase (allocated with xmalloc). Exits if EOF is encountered. If |
| 115 | * RP_ALLOW_STDIN is set, the passphrase will be read from stdin if no |
| 116 | * tty is available |
| 117 | */ |
| 118 | char * |
| 119 | read_passphrase(const char *prompt, int flags) |
| 120 | { |
| 121 | char *askpass = NULL, *ret, buf[1024]; |
| 122 | int rppflags, use_askpass = 0, ttyfd; |
| 123 | |
| 124 | rppflags = (flags & RP_ECHO) ? RPP_ECHO_ON : RPP_ECHO_OFF; |
| 125 | if (flags & RP_USE_ASKPASS) |
| 126 | use_askpass = 1; |
| 127 | else if (flags & RP_ALLOW_STDIN) { |
| 128 | if (!isatty(STDIN_FILENO)) { |
| 129 | debug("read_passphrase: stdin is not a tty"); |
| 130 | use_askpass = 1; |
| 131 | } |
| 132 | } else { |
| 133 | rppflags |= RPP_REQUIRE_TTY; |
| 134 | ttyfd = open(_PATH_TTY, O_RDWR); |
| 135 | if (ttyfd >= 0) |
| 136 | close(ttyfd); |
| 137 | else { |
| 138 | debug("read_passphrase: can't open %s: %s", _PATH_TTY, |
| 139 | strerror(errno)); |
| 140 | use_askpass = 1; |
| 141 | } |
| 142 | } |
| 143 | |
| 144 | if ((flags & RP_USE_ASKPASS) && getenv("DISPLAY") == NULL) |
| 145 | return (flags & RP_ALLOW_EOF) ? NULL : xstrdup(""); |
| 146 | |
| 147 | if (use_askpass && getenv("DISPLAY")) { |
| 148 | if (getenv(SSH_ASKPASS_ENV)) |
| 149 | askpass = getenv(SSH_ASKPASS_ENV); |
| 150 | else |
| 151 | askpass = _PATH_SSH_ASKPASS_DEFAULT; |
| 152 | if ((ret = ssh_askpass(askpass, prompt)) == NULL) |
| 153 | if (!(flags & RP_ALLOW_EOF)) |
| 154 | return xstrdup(""); |
| 155 | return ret; |
| 156 | } |
| 157 | |
| 158 | if (readpassphrase(prompt, buf, sizeof buf, rppflags) == NULL) { |
| 159 | if (flags & RP_ALLOW_EOF) |
| 160 | return NULL; |
| 161 | return xstrdup(""); |
| 162 | } |
| 163 | |
| 164 | ret = xstrdup(buf); |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame^] | 165 | explicit_bzero(buf, sizeof(buf)); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 166 | return ret; |
| 167 | } |
| 168 | |
| 169 | int |
| 170 | ask_permission(const char *fmt, ...) |
| 171 | { |
| 172 | va_list args; |
| 173 | char *p, prompt[1024]; |
| 174 | int allowed = 0; |
| 175 | |
| 176 | va_start(args, fmt); |
| 177 | vsnprintf(prompt, sizeof(prompt), fmt, args); |
| 178 | va_end(args); |
| 179 | |
| 180 | p = read_passphrase(prompt, RP_USE_ASKPASS|RP_ALLOW_EOF); |
| 181 | if (p != NULL) { |
| 182 | /* |
| 183 | * Accept empty responses and responses consisting |
| 184 | * of the word "yes" as affirmative. |
| 185 | */ |
| 186 | if (*p == '\0' || *p == '\n' || |
| 187 | strcasecmp(p, "yes") == 0) |
| 188 | allowed = 1; |
Adam Langley | d059297 | 2015-03-30 14:49:51 -0700 | [diff] [blame^] | 189 | free(p); |
Greg Hartman | bd77cf7 | 2015-02-25 13:21:06 -0800 | [diff] [blame] | 190 | } |
| 191 | |
| 192 | return (allowed); |
| 193 | } |