Annotation of src/usr.bin/ssh/readpass.c, Revision 1.49
1.49 ! djm 1: /* $OpenBSD: readpass.c,v 1.48 2010/12/15 00:49:27 djm 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) {
1.39 markus 72: permanently_drop_suid(getuid());
1.15 markus 73: close(p[0]);
74: if (dup2(p[1], STDOUT_FILENO) < 0)
75: fatal("ssh_askpass: dup2: %s", strerror(errno));
76: execlp(askpass, askpass, msg, (char *) 0);
77: fatal("ssh_askpass: exec(%s): %s", askpass, strerror(errno));
78: }
79: close(p[1]);
1.24 djm 80:
1.48 djm 81: len = 0;
1.24 djm 82: do {
1.48 djm 83: ssize_t r = read(p[0], buf + len, sizeof(buf) - 1 - len);
84:
85: if (r == -1 && errno == EINTR)
1.24 djm 86: continue;
1.48 djm 87: if (r <= 0)
1.24 djm 88: break;
1.48 djm 89: len += r;
1.24 djm 90: } while (sizeof(buf) - 1 - len > 0);
91: buf[len] = '\0';
92:
1.15 markus 93: close(p[0]);
1.48 djm 94: while ((ret = waitpid(pid, &status, 0)) < 0)
1.15 markus 95: if (errno != EINTR)
96: break;
1.48 djm 97: signal(SIGCHLD, osigchld);
98: if (ret == -1 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) {
1.28 markus 99: memset(buf, 0, sizeof(buf));
100: return NULL;
101: }
102:
1.23 markus 103: buf[strcspn(buf, "\r\n")] = '\0';
1.15 markus 104: pass = xstrdup(buf);
105: memset(buf, 0, sizeof(buf));
106: return pass;
107: }
108:
1.7 markus 109: /*
1.19 markus 110: * Reads a passphrase from /dev/tty with echo turned off/on. Returns the
111: * passphrase (allocated with xmalloc). Exits if EOF is encountered. If
112: * RP_ALLOW_STDIN is set, the passphrase will be read from stdin if no
113: * tty is available
1.12 markus 114: */
1.5 markus 115: char *
1.19 markus 116: read_passphrase(const char *prompt, int flags)
1.1 deraadt 117: {
1.19 markus 118: char *askpass = NULL, *ret, buf[1024];
119: int rppflags, use_askpass = 0, ttyfd;
1.15 markus 120:
1.19 markus 121: rppflags = (flags & RP_ECHO) ? RPP_ECHO_ON : RPP_ECHO_OFF;
1.30 djm 122: if (flags & RP_USE_ASKPASS)
123: use_askpass = 1;
124: else if (flags & RP_ALLOW_STDIN) {
1.33 markus 125: if (!isatty(STDIN_FILENO)) {
1.32 dtucker 126: debug("read_passphrase: stdin is not a tty");
1.15 markus 127: use_askpass = 1;
1.33 markus 128: }
1.15 markus 129: } else {
1.19 markus 130: rppflags |= RPP_REQUIRE_TTY;
1.25 markus 131: ttyfd = open(_PATH_TTY, O_RDWR);
1.15 markus 132: if (ttyfd >= 0)
133: close(ttyfd);
1.32 dtucker 134: else {
135: debug("read_passphrase: can't open %s: %s", _PATH_TTY,
136: strerror(errno));
1.15 markus 137: use_askpass = 1;
1.32 dtucker 138: }
1.15 markus 139: }
1.30 djm 140:
141: if ((flags & RP_USE_ASKPASS) && getenv("DISPLAY") == NULL)
142: return (flags & RP_ALLOW_EOF) ? NULL : xstrdup("");
1.15 markus 143:
144: if (use_askpass && getenv("DISPLAY")) {
145: if (getenv(SSH_ASKPASS_ENV))
146: askpass = getenv(SSH_ASKPASS_ENV);
147: else
148: askpass = _PATH_SSH_ASKPASS_DEFAULT;
1.28 markus 149: if ((ret = ssh_askpass(askpass, prompt)) == NULL)
150: if (!(flags & RP_ALLOW_EOF))
151: return xstrdup("");
152: return ret;
1.15 markus 153: }
154:
1.27 markus 155: if (readpassphrase(prompt, buf, sizeof buf, rppflags) == NULL) {
156: if (flags & RP_ALLOW_EOF)
157: return NULL;
1.20 markus 158: return xstrdup("");
1.27 markus 159: }
1.19 markus 160:
161: ret = xstrdup(buf);
162: memset(buf, 'x', sizeof buf);
163: return ret;
1.31 djm 164: }
165:
166: int
167: ask_permission(const char *fmt, ...)
168: {
169: va_list args;
170: char *p, prompt[1024];
171: int allowed = 0;
172:
173: va_start(args, fmt);
174: vsnprintf(prompt, sizeof(prompt), fmt, args);
175: va_end(args);
176:
177: p = read_passphrase(prompt, RP_USE_ASKPASS|RP_ALLOW_EOF);
178: if (p != NULL) {
179: /*
180: * Accept empty responses and responses consisting
181: * of the word "yes" as affirmative.
182: */
183: if (*p == '\0' || *p == '\n' ||
184: strcasecmp(p, "yes") == 0)
185: allowed = 1;
1.49 ! djm 186: free(p);
1.31 djm 187: }
188:
189: return (allowed);
1.1 deraadt 190: }
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