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-rw-r--r--readpass.c332
1 files changed, 332 insertions, 0 deletions
diff --git a/readpass.c b/readpass.c
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index 0000000..b52f3d6
--- /dev/null
+++ b/readpass.c
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+/* $OpenBSD: readpass.c,v 1.70 2022/05/27 04:27:49 dtucker 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, const char *env_hint)
+{
+ pid_t pid, ret;
+ size_t len;
+ char *pass;
+ int p[2], status;
+ char buf[1024];
+ void (*osigchld)(int);
+
+ if (fflush(stdout) != 0)
+ error_f("fflush: %s", strerror(errno));
+ if (askpass == NULL)
+ fatal("internal error: askpass undefined");
+ if (pipe(p) == -1) {
+ error_f("pipe: %s", strerror(errno));
+ return NULL;
+ }
+ osigchld = ssh_signal(SIGCHLD, SIG_DFL);
+ if ((pid = fork()) == -1) {
+ error_f("fork: %s", strerror(errno));
+ ssh_signal(SIGCHLD, osigchld);
+ return NULL;
+ }
+ if (pid == 0) {
+ close(p[0]);
+ if (dup2(p[1], STDOUT_FILENO) == -1)
+ fatal_f("dup2: %s", strerror(errno));
+ if (env_hint != NULL)
+ setenv("SSH_ASKPASS_PROMPT", env_hint, 1);
+ execlp(askpass, askpass, msg, (char *)NULL);
+ fatal_f("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;
+ ssh_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;
+}
+
+/* private/internal read_passphrase flags */
+#define RP_ASK_PERMISSION 0x8000 /* pass hint to askpass for confirm UI */
+
+/*
+ * 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 or askpass program is available
+ */
+char *
+read_passphrase(const char *prompt, int flags)
+{
+ char cr = '\r', *askpass = NULL, *ret, buf[1024];
+ int rppflags, ttyfd, use_askpass = 0, allow_askpass = 0;
+ const char *askpass_hint = NULL;
+ const char *s;
+
+ if ((s = getenv("DISPLAY")) != NULL)
+ allow_askpass = *s != '\0';
+ if ((s = getenv(SSH_ASKPASS_REQUIRE_ENV)) != NULL) {
+ if (strcasecmp(s, "force") == 0) {
+ use_askpass = 1;
+ allow_askpass = 1;
+ } else if (strcasecmp(s, "prefer") == 0)
+ use_askpass = allow_askpass;
+ else if (strcasecmp(s, "never") == 0)
+ allow_askpass = 0;
+ }
+
+ rppflags = (flags & RP_ECHO) ? RPP_ECHO_ON : RPP_ECHO_OFF;
+ if (use_askpass)
+ debug_f("requested to askpass");
+ else if (flags & RP_USE_ASKPASS)
+ use_askpass = 1;
+ else if (flags & RP_ALLOW_STDIN) {
+ if (!isatty(STDIN_FILENO)) {
+ debug_f("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_f("can't open %s: %s", _PATH_TTY,
+ strerror(errno));
+ use_askpass = 1;
+ }
+ }
+
+ if ((flags & RP_USE_ASKPASS) && !allow_askpass)
+ return (flags & RP_ALLOW_EOF) ? NULL : xstrdup("");
+
+ if (use_askpass && allow_askpass) {
+ if (getenv(SSH_ASKPASS_ENV))
+ askpass = getenv(SSH_ASKPASS_ENV);
+ else
+ askpass = _PATH_SSH_ASKPASS_DEFAULT;
+ if ((flags & RP_ASK_PERMISSION) != 0)
+ askpass_hint = "confirm";
+ if ((ret = ssh_askpass(askpass, prompt, askpass_hint)) == 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|RP_ASK_PERMISSION);
+ 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);
+}
+
+static void
+writemsg(const char *msg)
+{
+ (void)write(STDERR_FILENO, "\r", 1);
+ (void)write(STDERR_FILENO, msg, strlen(msg));
+ (void)write(STDERR_FILENO, "\r\n", 2);
+}
+
+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;
+ pid_t pid = -1;
+ void (*osigchld)(int) = NULL;
+ const char *askpass, *s;
+ struct notifier_ctx *ret = NULL;
+
+ va_start(args, fmt);
+ xvasprintf(&prompt, fmt, args);
+ va_end(args);
+
+ if (fflush(NULL) != 0)
+ error_f("fflush: %s", strerror(errno));
+ if (!force_askpass && isatty(STDERR_FILENO)) {
+ writemsg(prompt);
+ goto out_ctx;
+ }
+ if ((askpass = getenv("SSH_ASKPASS")) == NULL)
+ askpass = _PATH_SSH_ASKPASS_DEFAULT;
+ if (*askpass == '\0') {
+ debug3_f("cannot notify: no askpass");
+ goto out;
+ }
+ if (getenv("DISPLAY") == NULL &&
+ ((s = getenv(SSH_ASKPASS_REQUIRE_ENV)) == NULL ||
+ strcmp(s, "force") != 0)) {
+ debug3_f("cannot notify: no display");
+ goto out;
+ }
+ osigchld = ssh_signal(SIGCHLD, SIG_DFL);
+ if ((pid = fork()) == -1) {
+ error_f("fork: %s", strerror(errno));
+ ssh_signal(SIGCHLD, osigchld);
+ free(prompt);
+ return NULL;
+ }
+ if (pid == 0) {
+ if (stdfd_devnull(1, 1, 0) == -1)
+ fatal_f("stdfd_devnull failed");
+ closefrom(STDERR_FILENO + 1);
+ setenv("SSH_ASKPASS_PROMPT", "none", 1); /* hint to UI */
+ execlp(askpass, askpass, prompt, (char *)NULL);
+ error_f("exec(%s): %s", askpass, strerror(errno));
+ _exit(1);
+ /* NOTREACHED */
+ }
+ out_ctx:
+ if ((ret = calloc(1, sizeof(*ret))) == NULL) {
+ if (pid != -1)
+ kill(pid, SIGTERM);
+ fatal_f("calloc failed");
+ }
+ ret->pid = pid;
+ ret->osigchld = osigchld;
+ out:
+ free(prompt);
+ return ret;
+}
+
+void
+notify_complete(struct notifier_ctx *ctx, const char *fmt, ...)
+{
+ int ret;
+ char *msg = NULL;
+ va_list args;
+
+ if (ctx != NULL && fmt != NULL && ctx->pid == -1) {
+ /*
+ * notify_start wrote to stderr, so send conclusion message
+ * there too
+ */
+ va_start(args, fmt);
+ xvasprintf(&msg, fmt, args);
+ va_end(args);
+ writemsg(msg);
+ free(msg);
+ }
+
+ 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_f("waitpid: %s", strerror(errno));
+ ssh_signal(SIGCHLD, ctx->osigchld);
+ free(ctx);
+}