Annotation of src/usr.bin/ssh/readpass.c, Revision 1.53
1.53 ! tb 1: /* $OpenBSD: readpass.c,v 1.52 2018/07/18 11:34:04 dtucker Exp $ */
1.1 deraadt 2: /*
1.26 markus 3: * Copyright (c) 2001 Markus Friedl. All rights reserved.
1.8 deraadt 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: *
1.26 markus 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.
1.6 deraadt 24: */
1.35 stevesk 25:
26: #include <sys/types.h>
27: #include <sys/wait.h>
1.19 markus 28:
1.42 stevesk 29: #include <errno.h>
1.40 stevesk 30: #include <fcntl.h>
1.34 stevesk 31: #include <paths.h>
1.19 markus 32: #include <readpassphrase.h>
1.48 djm 33: #include <signal.h>
1.41 stevesk 34: #include <stdarg.h>
1.46 stevesk 35: #include <stdio.h>
1.45 stevesk 36: #include <stdlib.h>
1.44 stevesk 37: #include <string.h>
1.43 stevesk 38: #include <unistd.h>
1.1 deraadt 39:
40: #include "xmalloc.h"
1.29 djm 41: #include "misc.h"
1.15 markus 42: #include "pathnames.h"
43: #include "log.h"
44: #include "ssh.h"
1.38 markus 45: #include "uidswap.h"
1.15 markus 46:
1.18 itojun 47: static char *
1.16 mouring 48: ssh_askpass(char *askpass, const char *msg)
1.15 markus 49: {
1.48 djm 50: pid_t pid, ret;
1.15 markus 51: size_t len;
1.23 markus 52: char *pass;
1.48 djm 53: int p[2], status;
1.15 markus 54: char buf[1024];
1.48 djm 55: void (*osigchld)(int);
1.15 markus 56:
57: if (fflush(stdout) != 0)
58: error("ssh_askpass: fflush: %s", strerror(errno));
59: if (askpass == NULL)
60: fatal("internal error: askpass undefined");
1.21 markus 61: if (pipe(p) < 0) {
62: error("ssh_askpass: pipe: %s", strerror(errno));
1.28 markus 63: return NULL;
1.21 markus 64: }
1.48 djm 65: osigchld = signal(SIGCHLD, SIG_DFL);
1.21 markus 66: if ((pid = fork()) < 0) {
67: error("ssh_askpass: fork: %s", strerror(errno));
1.48 djm 68: signal(SIGCHLD, osigchld);
1.28 markus 69: return NULL;
1.21 markus 70: }
1.15 markus 71: if (pid == 0) {
72: close(p[0]);
73: if (dup2(p[1], STDOUT_FILENO) < 0)
74: fatal("ssh_askpass: dup2: %s", strerror(errno));
1.51 mmcc 75: execlp(askpass, askpass, msg, (char *)NULL);
1.15 markus 76: fatal("ssh_askpass: exec(%s): %s", askpass, strerror(errno));
77: }
78: close(p[1]);
1.24 djm 79:
1.48 djm 80: len = 0;
1.24 djm 81: do {
1.48 djm 82: ssize_t r = read(p[0], buf + len, sizeof(buf) - 1 - len);
83:
84: if (r == -1 && errno == EINTR)
1.24 djm 85: continue;
1.48 djm 86: if (r <= 0)
1.24 djm 87: break;
1.48 djm 88: len += r;
1.24 djm 89: } while (sizeof(buf) - 1 - len > 0);
90: buf[len] = '\0';
91:
1.15 markus 92: close(p[0]);
1.48 djm 93: while ((ret = waitpid(pid, &status, 0)) < 0)
1.15 markus 94: if (errno != EINTR)
95: break;
1.48 djm 96: signal(SIGCHLD, osigchld);
97: if (ret == -1 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) {
1.50 djm 98: explicit_bzero(buf, sizeof(buf));
1.28 markus 99: return NULL;
100: }
101:
1.23 markus 102: buf[strcspn(buf, "\r\n")] = '\0';
1.15 markus 103: pass = xstrdup(buf);
1.50 djm 104: explicit_bzero(buf, sizeof(buf));
1.15 markus 105: return pass;
106: }
107:
1.7 markus 108: /*
1.19 markus 109: * Reads a passphrase from /dev/tty with echo turned off/on. Returns the
110: * passphrase (allocated with xmalloc). Exits if EOF is encountered. If
111: * RP_ALLOW_STDIN is set, the passphrase will be read from stdin if no
112: * tty is available
1.12 markus 113: */
1.5 markus 114: char *
1.19 markus 115: read_passphrase(const char *prompt, int flags)
1.1 deraadt 116: {
1.53 ! tb 117: char cr = '\r', *askpass = NULL, *ret, buf[1024];
1.19 markus 118: int rppflags, use_askpass = 0, ttyfd;
1.15 markus 119:
1.19 markus 120: rppflags = (flags & RP_ECHO) ? RPP_ECHO_ON : RPP_ECHO_OFF;
1.30 djm 121: if (flags & RP_USE_ASKPASS)
122: use_askpass = 1;
123: else if (flags & RP_ALLOW_STDIN) {
1.33 markus 124: if (!isatty(STDIN_FILENO)) {
1.32 dtucker 125: debug("read_passphrase: stdin is not a tty");
1.15 markus 126: use_askpass = 1;
1.33 markus 127: }
1.15 markus 128: } else {
1.19 markus 129: rppflags |= RPP_REQUIRE_TTY;
1.25 markus 130: ttyfd = open(_PATH_TTY, O_RDWR);
1.53 ! tb 131: if (ttyfd >= 0) {
! 132: /*
! 133: * If we're on a tty, ensure that show the prompt at
! 134: * the beginning of the line. This will hopefully
! 135: * clobber any password characters the user has
! 136: * optimistically typed before echo is disabled.
! 137: */
! 138: (void)write(ttyfd, &cr, 1);
1.15 markus 139: close(ttyfd);
1.53 ! tb 140: } else {
1.32 dtucker 141: debug("read_passphrase: can't open %s: %s", _PATH_TTY,
142: strerror(errno));
1.15 markus 143: use_askpass = 1;
1.32 dtucker 144: }
1.15 markus 145: }
1.30 djm 146:
147: if ((flags & RP_USE_ASKPASS) && getenv("DISPLAY") == NULL)
148: return (flags & RP_ALLOW_EOF) ? NULL : xstrdup("");
1.15 markus 149:
150: if (use_askpass && getenv("DISPLAY")) {
151: if (getenv(SSH_ASKPASS_ENV))
152: askpass = getenv(SSH_ASKPASS_ENV);
153: else
154: askpass = _PATH_SSH_ASKPASS_DEFAULT;
1.28 markus 155: if ((ret = ssh_askpass(askpass, prompt)) == NULL)
156: if (!(flags & RP_ALLOW_EOF))
157: return xstrdup("");
158: return ret;
1.15 markus 159: }
160:
1.27 markus 161: if (readpassphrase(prompt, buf, sizeof buf, rppflags) == NULL) {
162: if (flags & RP_ALLOW_EOF)
163: return NULL;
1.20 markus 164: return xstrdup("");
1.27 markus 165: }
1.19 markus 166:
167: ret = xstrdup(buf);
1.50 djm 168: explicit_bzero(buf, sizeof(buf));
1.19 markus 169: return ret;
1.31 djm 170: }
171:
172: int
173: ask_permission(const char *fmt, ...)
174: {
175: va_list args;
176: char *p, prompt[1024];
177: int allowed = 0;
178:
179: va_start(args, fmt);
180: vsnprintf(prompt, sizeof(prompt), fmt, args);
181: va_end(args);
182:
183: p = read_passphrase(prompt, RP_USE_ASKPASS|RP_ALLOW_EOF);
184: if (p != NULL) {
185: /*
186: * Accept empty responses and responses consisting
187: * of the word "yes" as affirmative.
188: */
189: if (*p == '\0' || *p == '\n' ||
190: strcasecmp(p, "yes") == 0)
191: allowed = 1;
1.49 djm 192: free(p);
1.31 djm 193: }
194:
195: return (allowed);
1.1 deraadt 196: }
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