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/*
* Copyright (c) 1993-1996,1998-2005, 2007-2013
* Todd C. Miller <Todd.Miller@courtesan.com>
*
* 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.
*/
#include <config.h>
#include <sys/types.h>
#include <sys/time.h>
#include <stdio.h>
#ifdef STDC_HEADERS
# include <stdlib.h>
# include <stddef.h>
#else
# ifdef HAVE_STDLIB_H
# include <stdlib.h>
# endif
#endif /* STDC_HEADERS */
#ifdef HAVE_STRING_H
# include <string.h>
#endif /* HAVE_STRING_H */
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif /* HAVE_STRINGS_H */
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif /* HAVE_UNISTD_H */
#ifdef TIME_WITH_SYS_TIME
# include <time.h>
#endif
#include <errno.h>
#include <fcntl.h>
#include <pwd.h>
#include <grp.h>
#include "sudoers.h"
#include "check.h"
static bool display_lecture(int);
static struct passwd *get_authpw(void);
/*
* Returns true if the user successfully authenticates, false if not
* or -1 on error.
*/
static int
check_user_interactive(int validated, int mode, struct passwd *auth_pw)
{
int status, rval = true;
debug_decl(check_user_interactive, SUDO_DEBUG_AUTH)
/* Always need a password when -k was specified with the command. */
if (ISSET(mode, MODE_IGNORE_TICKET))
SET(validated, FLAG_CHECK_USER);
if (build_timestamp(auth_pw) == -1) {
rval = -1;
goto done;
}
status = timestamp_status(auth_pw);
if (status != TS_CURRENT || ISSET(validated, FLAG_CHECK_USER)) {
char *prompt;
bool lectured;
/* 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);
rval = -1;
goto done;
}
/* XXX - should not lecture if askpass helper is being used. */
lectured = display_lecture(status);
/* Expand any escapes in the prompt. */
prompt = expand_prompt(user_prompt ? user_prompt : def_passprompt,
user_name, user_shost);
rval = verify_user(auth_pw, prompt, validated);
if (rval == true && lectured)
set_lectured();
efree(prompt);
}
/* Only update timestamp if user was validated. */
if (rval == true && ISSET(validated, VALIDATE_OK) &&
!ISSET(mode, MODE_IGNORE_TICKET) && status != TS_ERROR)
update_timestamp(auth_pw);
done:
debug_return_bool(rval);
}
/*
* Returns true if the user successfully authenticates, false if not
* or -1 on error.
*/
int
check_user(int validated, int mode)
{
struct passwd *auth_pw;
int rval = true;
debug_decl(check_user, SUDO_DEBUG_AUTH)
/*
* Init authentication system regardless of whether we need a password.
* Required for proper PAM session support.
*/
auth_pw = get_authpw();
if (sudo_auth_init(auth_pw) == -1) {
rval = -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())
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
goto done;
}
rval = check_user_interactive(validated, mode, auth_pw);
done:
sudo_auth_cleanup(auth_pw);
sudo_pw_delref(auth_pw);
debug_return_bool(rval);
}
/*
* Display sudo lecture (standard or custom).
* Returns true if the user was lectured, else false.
*/
static bool
display_lecture(int status)
{
FILE *fp;
char buf[BUFSIZ];
ssize_t nread;
struct sudo_conv_message msg;
struct sudo_conv_reply repl;
debug_decl(lecture, SUDO_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 && (fp = fopen(def_lecture_file, "r")) != NULL) {
while ((nread = fread(buf, sizeof(char), sizeof(buf) - 1, fp)) != 0) {
buf[nread] = '\0';
msg.msg_type = SUDO_CONV_ERROR_MSG;
msg.msg = buf;
sudo_conv(1, &msg, &repl);
}
fclose(fp);
} else {
msg.msg_type = SUDO_CONV_ERROR_MSG;
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);
}
debug_return_bool(true);
}
/*
* Checks if the user is exempt from supplying a password.
*/
bool
user_is_exempt(void)
{
bool rval = false;
debug_decl(user_is_exempt, SUDO_DEBUG_AUTH)
if (def_exempt_group)
rval = user_in_group(sudo_user.pw, def_exempt_group);
debug_return_bool(rval);
}
/*
* 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(void)
{
struct passwd *pw;
debug_decl(get_authpw, SUDO_DEBUG_AUTH)
if (def_rootpw) {
if ((pw = sudo_getpwuid(ROOT_UID)) == NULL)
log_fatal(0, N_("unknown uid: %u"), ROOT_UID);
} else if (def_runaspw) {
if ((pw = sudo_getpwnam(def_runas_default)) == NULL)
log_fatal(0, N_("unknown user: %s"), def_runas_default);
} else if (def_targetpw) {
if (runas_pw->pw_name == NULL)
log_fatal(NO_MAIL|MSG_ONLY, N_("unknown uid: %u"),
(unsigned int) runas_pw->pw_uid);
sudo_pw_addref(runas_pw);
pw = runas_pw;
} else {
sudo_pw_addref(sudo_user.pw);
pw = sudo_user.pw;
}
debug_return_ptr(pw);
}
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