Adding upstream version 1.9.5p2.upstream/1.9.5p2upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 373 insertions, 0 deletions

diff --git a/plugins/sudoers/check.c b/plugins/sudoers/check.c
new file mode 100644
index 0000000..4a7bb5e
--- /dev/null
+++ b/plugins/sudoers/check.c
@@ -0,0 +1,373 @@
+/*
+ * SPDX-License-Identifier: ISC
+ *
+ * Copyright (c) 1993-1996,1998-2005, 2007-2018
+ *	Todd C. Miller <Todd.Miller@sudo.ws>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * Sponsored in part by the Defense Advanced Research Projects
+ * Agency (DARPA) and Air Force Research Laboratory, Air Force
+ * Materiel Command, USAF, under agreement number F39502-99-1-0512.
+ */
+
+/*
+ * This is an open source non-commercial project. Dear PVS-Studio, please check it.
+ * PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+ */
+
+#include <config.h>
+
+#include <sys/types.h>			/* for ssize_t */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <time.h>
+#include <errno.h>
+#include <pwd.h>
+#include <grp.h>
+
+#include "sudoers.h"
+#include "check.h"
+
+static bool display_lecture(int);
+static struct passwd *get_authpw(int);
+
+struct getpass_closure {
+    int tstat;
+    void *cookie;
+    struct passwd *auth_pw;
+};
+
+/*
+ * Called when getpass is suspended so we can drop the lock.
+ */
+static int
+getpass_suspend(int signo, void *vclosure)
+{
+    struct getpass_closure *closure = vclosure;
+
+    timestamp_close(closure->cookie);
+    closure->cookie = NULL;
+    return 0;
+}
+
+/*
+ * Called when getpass is resumed so we can reacquire the lock.
+ */
+static int
+getpass_resume(int signo, void *vclosure)
+{
+    struct getpass_closure *closure = vclosure;
+
+    closure->cookie = timestamp_open(user_name, user_sid);
+    if (closure->cookie == NULL)
+	return -1;
+    if (!timestamp_lock(closure->cookie, closure->auth_pw))
+	return -1;
+    return 0;
+}
+
+/*
+ * Returns true if the user successfully authenticates, false if not
+ * or -1 on fatal error.
+ */
+static int
+check_user_interactive(int validated, int mode, struct getpass_closure *closure)
+{
+    struct sudo_conv_callback cb, *callback = NULL;
+    int ret = -1;
+    char *prompt;
+    bool lectured;
+    debug_decl(check_user_interactive, SUDOERS_DEBUG_AUTH);
+
+    /* Open, lock and read time stamp file if we are using it. */
+    if (!ISSET(mode, MODE_IGNORE_TICKET)) {
+	/* Open time stamp file and check its status. */
+	closure->cookie = timestamp_open(user_name, user_sid);
+	if (timestamp_lock(closure->cookie, closure->auth_pw))
+	    closure->tstat = timestamp_status(closure->cookie, closure->auth_pw);
+
+	/* Construct callback for getpass function. */
+	memset(&cb, 0, sizeof(cb));
+	cb.version = SUDO_CONV_CALLBACK_VERSION;
+	cb.closure = closure;
+	cb.on_suspend = getpass_suspend;
+	cb.on_resume = getpass_resume;
+	callback = &cb;
+    }
+
+    switch (closure->tstat) {
+    case TS_FATAL:
+	/* Fatal error (usually setuid failure), unsafe to proceed. */
+	goto done;
+
+    case TS_CURRENT:
+	/* Time stamp file is valid and current. */
+	if (!ISSET(validated, FLAG_CHECK_USER)) {
+	    ret = true;
+	    break;
+	}
+	sudo_debug_printf(SUDO_DEBUG_INFO,
+	    "%s: check user flag overrides time stamp", __func__);
+	FALLTHROUGH;
+
+    default:
+	/* Bail out if we are non-interactive and a password is required */
+	if (ISSET(mode, MODE_NONINTERACTIVE)) {
+	    validated |= FLAG_NON_INTERACTIVE;
+	    log_auth_failure(validated, 0);
+	    goto done;
+	}
+
+	/* XXX - should not lecture if askpass helper is being used. */
+	lectured = display_lecture(closure->tstat);
+
+	/* Expand any escapes in the prompt. */
+	prompt = expand_prompt(user_prompt ? user_prompt : def_passprompt,
+	    closure->auth_pw->pw_name);
+	if (prompt == NULL)
+	    goto done;
+
+	ret = verify_user(closure->auth_pw, prompt, validated, callback);
+	if (ret == true && lectured)
+	    (void)set_lectured();	/* lecture error not fatal */
+	free(prompt);
+	break;
+    }
+
+done:
+    debug_return_int(ret);
+}
+
+/*
+ * Returns true if the user successfully authenticates, false if not
+ * or -1 on error.
+ */
+int
+check_user(int validated, int mode)
+{
+    struct getpass_closure closure = { TS_ERROR };
+    int ret = -1;
+    bool exempt = false;
+    debug_decl(check_user, SUDOERS_DEBUG_AUTH);
+
+    /*
+     * Init authentication system regardless of whether we need a password.
+     * Required for proper PAM session support.
+     */
+    if ((closure.auth_pw = get_authpw(mode)) == NULL)
+	goto done;
+    if (sudo_auth_init(closure.auth_pw) == -1)
+	goto done;
+
+    /*
+     * Don't prompt for the root passwd or if the user is exempt.
+     * If the user is not changing uid/gid, no need for a password.
+     */
+    if (!def_authenticate || user_is_exempt()) {
+	sudo_debug_printf(SUDO_DEBUG_INFO, "%s: %s", __func__,
+	    !def_authenticate ? "authentication disabled" :
+	    "user exempt from authentication");
+	exempt = true;
+	ret = true;
+	goto done;
+    }
+    if (user_uid == 0 || (user_uid == runas_pw->pw_uid &&
+	(!runas_gr || user_in_group(sudo_user.pw, runas_gr->gr_name)))) {
+#ifdef HAVE_SELINUX
+	if (user_role == NULL && user_type == NULL)
+#endif
+#ifdef HAVE_PRIV_SET
+	if (runas_privs == NULL && runas_limitprivs == NULL)
+#endif
+	{
+	    sudo_debug_printf(SUDO_DEBUG_INFO,
+		"%s: user running command as self", __func__);
+	    ret = true;
+	    goto done;
+	}
+    }
+
+    ret = check_user_interactive(validated, mode, &closure);
+
+done:
+    if (ret == true) {
+	/* The approval function may disallow a user post-authentication. */
+	ret = sudo_auth_approval(closure.auth_pw, validated, exempt);
+
+	/*
+	 * Only update time stamp if user validated and was approved.
+	 * Failure to update the time stamp is not a fatal error.
+	 */
+	if (ret == true && closure.tstat != TS_ERROR) {
+	    if (ISSET(validated, VALIDATE_SUCCESS))
+		(void)timestamp_update(closure.cookie, closure.auth_pw);
+	}
+    }
+    timestamp_close(closure.cookie);
+    sudo_auth_cleanup(closure.auth_pw, !ISSET(validated, VALIDATE_SUCCESS));
+    if (closure.auth_pw != NULL)
+	sudo_pw_delref(closure.auth_pw);
+
+    debug_return_int(ret);
+}
+
+/*
+ * Display sudo lecture (standard or custom).
+ * Returns true if the user was lectured, else false.
+ */
+static bool
+display_lecture(int status)
+{
+    struct sudo_conv_message msg;
+    struct sudo_conv_reply repl;
+    char buf[BUFSIZ];
+    struct stat sb;
+    ssize_t nread;
+    int fd;
+    debug_decl(lecture, SUDOERS_DEBUG_AUTH);
+
+    if (def_lecture == never ||
+	(def_lecture == once && already_lectured(status)))
+	debug_return_bool(false);
+
+    memset(&msg, 0, sizeof(msg));
+    memset(&repl, 0, sizeof(repl));
+
+    if (def_lecture_file) {
+	fd = open(def_lecture_file, O_RDONLY|O_NONBLOCK);
+	if (fd != -1 && fstat(fd, &sb) == 0) {
+	    if (S_ISREG(sb.st_mode)) {
+		(void) fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) & ~O_NONBLOCK);
+		while ((nread = read(fd, buf, sizeof(buf) - 1)) > 0) {
+		    buf[nread] = '\0';
+		    msg.msg_type = SUDO_CONV_ERROR_MSG|SUDO_CONV_PREFER_TTY;
+		    msg.msg = buf;
+		    sudo_conv(1, &msg, &repl, NULL);
+		}
+		close(fd);
+		if (nread == -1) {
+		    log_warning(SLOG_RAW_MSG,
+			N_("error reading lecture file %s"), def_lecture_file);
+		    debug_return_bool(false);
+		}
+		debug_return_bool(true);
+	    } else {
+		log_warningx(SLOG_RAW_MSG,
+		    N_("ignoring lecture file %s: not a regular file"),
+		    def_lecture_file);
+	    }
+	} else {
+	    log_warning(SLOG_RAW_MSG|SLOG_NO_STDERR, N_("unable to open %s"),
+		def_lecture_file);
+	}
+	if (fd != -1)
+	    close(fd);
+    }
+
+    /* Default sudo lecture. */
+    msg.msg_type = SUDO_CONV_ERROR_MSG|SUDO_CONV_PREFER_TTY;
+    msg.msg = _("\n"
+	"We trust you have received the usual lecture from the local System\n"
+	"Administrator. It usually boils down to these three things:\n\n"
+	"    #1) Respect the privacy of others.\n"
+	"    #2) Think before you type.\n"
+	"    #3) With great power comes great responsibility.\n\n");
+    sudo_conv(1, &msg, &repl, NULL);
+    debug_return_bool(true);
+}
+
+/*
+ * Checks if the user is exempt from supplying a password.
+ */
+bool
+user_is_exempt(void)
+{
+    bool ret = false;
+    debug_decl(user_is_exempt, SUDOERS_DEBUG_AUTH);
+
+    if (def_exempt_group)
+	ret = user_in_group(sudo_user.pw, def_exempt_group);
+    debug_return_bool(ret);
+}
+
+/*
+ * Get passwd entry for the user we are going to authenticate as.
+ * By default, this is the user invoking sudo.  In the most common
+ * case, this matches sudo_user.pw or runas_pw.
+ */
+static struct passwd *
+get_authpw(int mode)
+{
+    struct passwd *pw = NULL;
+    debug_decl(get_authpw, SUDOERS_DEBUG_AUTH);
+
+    if (ISSET(mode, (MODE_CHECK|MODE_LIST))) {
+	/* In list mode we always prompt for the user's password. */
+	sudo_pw_addref(sudo_user.pw);
+	pw = sudo_user.pw;
+    } else {
+	if (def_rootpw) {
+	    if ((pw = sudo_getpwuid(ROOT_UID)) == NULL) {
+		log_warningx(SLOG_SEND_MAIL, N_("unknown uid: %u"), ROOT_UID);
+	    }
+	} else if (def_runaspw) {
+	    if ((pw = sudo_getpwnam(def_runas_default)) == NULL) {
+		log_warningx(SLOG_SEND_MAIL,
+		    N_("unknown user: %s"), def_runas_default);
+	    }
+	} else if (def_targetpw) {
+	    if (runas_pw->pw_name == NULL) {
+		/* This should never be NULL as we fake up the passwd struct */
+		log_warningx(SLOG_RAW_MSG, N_("unknown uid: %u"),
+		    (unsigned int) runas_pw->pw_uid);
+	    } else {
+		sudo_pw_addref(runas_pw);
+		pw = runas_pw;
+	    }
+	} else {
+	    sudo_pw_addref(sudo_user.pw);
+	    pw = sudo_user.pw;
+	}
+    }
+
+    debug_return_ptr(pw);
+}
+
+/*
+ * Returns true if the specified shell is allowed by /etc/shells, else false.
+ */
+bool
+check_user_shell(const struct passwd *pw)
+{
+    const char *shell;
+    debug_decl(check_user_shell, SUDOERS_DEBUG_AUTH);
+
+    if (!def_runas_check_shell)
+	debug_return_bool(true);
+
+    sudo_debug_printf(SUDO_DEBUG_INFO,
+	"%s: checking /etc/shells for %s", __func__, pw->pw_shell);
+
+    setusershell();
+    while ((shell = getusershell()) != NULL) {
+	if (strcmp(shell, pw->pw_shell) == 0)
+	    debug_return_bool(true);
+    }
+    endusershell();
+
+    debug_return_bool(false);
+}