isa/sudo
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
Files
cf7ec7a3ccf873067c29f265e39c5756d150de1f
sudo/plugins/sudoers/check.c
Todd C. Miller 39b9b97dbc Fix indentation
2011-01-27 10:03:59 -05:00

728 lines
19 KiB
C
Raw Blame History

/*
* Copyright (c) 1993-1996,1998-2005, 2007-2011
* 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/param.h>
#include <sys/time.h>
#include <sys/stat.h>
#ifdef __linux__
# include <sys/vfs.h>
#endif
#if defined(__sun) && defined(__SVR4)
# include <sys/statvfs.h>
#endif
#ifndef __TANDEM
# include <sys/file.h>
#endif
#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 */
#if TIME_WITH_SYS_TIME
# include <time.h>
#endif
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <pwd.h>
#include <grp.h>
#include "sudoers.h"
/* Status codes for timestamp_status() */
#define TS_CURRENT 0
#define TS_OLD 1
#define TS_MISSING 2
#define TS_NOFILE 3
#define TS_ERROR 4
/* Flags for timestamp_status() */
#define TS_MAKE_DIRS 1
#define TS_REMOVE 2
/*
* Info stored in tty ticket from stat(2) to help with tty matching.
*/
static struct tty_info {
dev_t dev; /* ID of device tty resides on */
dev_t rdev; /* tty device ID */
ino_t ino; /* tty inode number */
struct timeval ctime; /* tty inode change time */
} tty_info;
static int build_timestamp(char **, char **);
static int timestamp_status(char *, char *, char *, int);
static char *expand_prompt(char *, char *, char *);
static void lecture(int);
static void update_timestamp(char *, char *);
static int tty_is_devpts(const char *);
static struct passwd *get_authpw(void);
/*
* Returns TRUE if the user successfully authenticates, else FALSE.
*/
int
check_user(int validated, int mode)
{
char *timestampdir = NULL;
char *timestampfile = NULL;
char *prompt;
struct stat sb;
int status, rval = TRUE;
/* Stash the tty's ctime for tty ticket comparison. */
if (def_tty_tickets && user_ttypath && stat(user_ttypath, &sb) == 0) {
tty_info.dev = sb.st_dev;
tty_info.ino = sb.st_ino;
tty_info.rdev = sb.st_rdev;
if (tty_is_devpts(user_ttypath))
ctim_get(&sb, &tty_info.ctime);
}
/* Always prompt for a password when -k was specified with the command. */
if (ISSET(mode, MODE_IGNORE_TICKET)) {
SET(validated, FLAG_CHECK_USER);
} else {
/*
* 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 (user_uid == 0 || (user_uid == runas_pw->pw_uid &&
(!runas_gr || user_in_group(sudo_user.pw, runas_gr->gr_name))) ||
user_is_exempt())
return TRUE;
}
if (build_timestamp(&timestampdir, &timestampfile) == -1)
return -1;
status = timestamp_status(timestampdir, timestampfile, user_name,
TS_MAKE_DIRS);
if (status != TS_CURRENT || ISSET(validated, FLAG_CHECK_USER)) {
struct passwd *auth_pw;
/* Bail out if we are non-interactive and a password is required */
if (ISSET(mode, MODE_NONINTERACTIVE)) {
warningx("sorry, a password is required to run %s", getprogname());
return -1;
}
/* XXX - should not lecture if askpass help is being used. */
lecture(status);
/* Expand any escapes in the prompt. */
prompt = expand_prompt(user_prompt ? user_prompt : def_passprompt,
user_name, user_shost);
auth_pw = get_authpw();
rval = verify_user(auth_pw, prompt);
pw_delref(auth_pw);
}
/* Only update timestamp if user was validated. */
if (rval == TRUE && ISSET(validated, VALIDATE_OK) &&
!ISSET(mode, MODE_IGNORE_TICKET) && status != TS_ERROR)
update_timestamp(timestampdir, timestampfile);
efree(timestampdir);
efree(timestampfile);
return rval;
}
static const char lecture_text[] = "\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";
/*
* Standard sudo lecture.
*/
static void
lecture(int status)
{
FILE *fp;
char buf[BUFSIZ];
ssize_t nread;
struct sudo_conv_message msg;
struct sudo_conv_reply repl;
if (def_lecture == never ||
(def_lecture == once && status != TS_MISSING && status != TS_ERROR))
return;
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[sizeof(buf) - 1] = '\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 = lecture_text;
sudo_conv(1, &msg, &repl);
}
}
/*
* Update the time on the timestamp file/dir or create it if necessary.
*/
static void
update_timestamp(char *timestampdir, char *timestampfile)
{
/* If using tty timestamps but we have no tty there is nothing to do. */
if (def_tty_tickets && !user_ttypath)
return;
if (timestamp_uid != 0)
set_perms(PERM_TIMESTAMP);
if (timestampfile) {
/*
* Store tty info in timestamp file
*/
int fd = open(timestampfile, O_WRONLY|O_CREAT, 0600);
if (fd == -1)
log_error(NO_EXIT|USE_ERRNO, "Can't open %s", timestampfile);
else {
lock_file(fd, SUDO_LOCK);
if (write(fd, &tty_info, sizeof(tty_info)) != sizeof(tty_info))
log_error(NO_EXIT|USE_ERRNO, "Can't write %s", timestampfile);
close(fd);
}
} else {
if (touch(-1, timestampdir, NULL) == -1) {
if (mkdir(timestampdir, 0700) == -1)
log_error(NO_EXIT|USE_ERRNO, "Can't mkdir %s", timestampdir);
}
}
if (timestamp_uid != 0)
restore_perms();
}
/*
* Expand %h and %u escapes in the prompt and pass back the dynamically
* allocated result. Returns the same string if there are no escapes.
*/
static char *
expand_prompt(char *old_prompt, char *user, char *host)
{
size_t len, n;
int subst;
char *p, *np, *new_prompt, *endp;
/* How much space do we need to malloc for the prompt? */
subst = 0;
for (p = old_prompt, len = strlen(old_prompt); *p; p++) {
if (p[0] =='%') {
switch (p[1]) {
case 'h':
p++;
len += strlen(user_shost) - 2;
subst = 1;
break;
case 'H':
p++;
len += strlen(user_host) - 2;
subst = 1;
break;
case 'p':
p++;
if (def_rootpw)
len += 2;
else if (def_targetpw || def_runaspw)
len += strlen(runas_pw->pw_name) - 2;
else
len += strlen(user_name) - 2;
subst = 1;
break;
case 'u':
p++;
len += strlen(user_name) - 2;
subst = 1;
break;
case 'U':
p++;
len += strlen(runas_pw->pw_name) - 2;
subst = 1;
break;
case '%':
p++;
len--;
subst = 1;
break;
default:
break;
}
}
}
if (subst) {
new_prompt = emalloc(++len);
endp = new_prompt + len;
for (p = old_prompt, np = new_prompt; *p; p++) {
if (p[0] =='%') {
switch (p[1]) {
case 'h':
p++;
n = strlcpy(np, user_shost, np - endp);
if (n >= np - endp)
goto oflow;
np += n;
continue;
case 'H':
p++;
n = strlcpy(np, user_host, np - endp);
if (n >= np - endp)
goto oflow;
np += n;
continue;
case 'p':
p++;
if (def_rootpw)
n = strlcpy(np, "root", np - endp);
else if (def_targetpw || def_runaspw)
n = strlcpy(np, runas_pw->pw_name, np - endp);
else
n = strlcpy(np, user_name, np - endp);
if (n >= np - endp)
goto oflow;
np += n;
continue;
case 'u':
p++;
n = strlcpy(np, user_name, np - endp);
if (n >= np - endp)
goto oflow;
np += n;
continue;
case 'U':
p++;
n = strlcpy(np, runas_pw->pw_name, np - endp);
if (n >= np - endp)
goto oflow;
np += n;
continue;
case '%':
/* convert %% -> % */
p++;
break;
default:
/* no conversion */
break;
}
}
*np++ = *p;
if (np >= endp)
goto oflow;
}
*np = '\0';
} else
new_prompt = old_prompt;
return new_prompt;
oflow:
/* We pre-allocate enough space, so this should never happen. */
errorx(1, "internal error, expand_prompt() overflow");
}
/*
* Checks if the user is exempt from supplying a password.
*/
int
user_is_exempt(void)
{
if (!def_exempt_group)
return FALSE;
return user_in_group(sudo_user.pw, def_exempt_group);
}
/*
* Fills in timestampdir as well as timestampfile if using tty tickets.
*/
static int
build_timestamp(char **timestampdir, char **timestampfile)
{
char *dirparent;
int len;
dirparent = def_timestampdir;
len = easprintf(timestampdir, "%s/%s", dirparent, user_name);
if (len >= PATH_MAX) {
log_error(0, "timestamp path too long: %s", *timestampdir);
return -1;
}
/*
* Timestamp file may be a file in the directory or NUL to use
* the directory as the timestamp.
*/
if (def_tty_tickets) {
char *p;
if ((p = strrchr(user_tty, '/')))
p++;
else
p = user_tty;
if (def_targetpw)
len = easprintf(timestampfile, "%s/%s/%s:%s", dirparent, user_name,
p, runas_pw->pw_name);
else
len = easprintf(timestampfile, "%s/%s/%s", dirparent, user_name, p);
if (len >= PATH_MAX) {
log_error(0, "timestamp path too long: %s", *timestampfile);
return -1;
}
} else if (def_targetpw) {
len = easprintf(timestampfile, "%s/%s/%s", dirparent, user_name,
runas_pw->pw_name);
if (len >= PATH_MAX) {
log_error(0, "timestamp path too long: %s", *timestampfile);
return -1;
}
} else
*timestampfile = NULL;
return len;
}
/*
* Check the timestamp file and directory and return their status.
*/
static int
timestamp_status(char *timestampdir, char *timestampfile, char *user, int flags)
{
struct stat sb;
struct timeval boottime, mtime;
time_t now;
char *dirparent = def_timestampdir;
int status = TS_ERROR; /* assume the worst */
if (timestamp_uid != 0)
set_perms(PERM_TIMESTAMP);
/*
* Sanity check dirparent and make it if it doesn't already exist.
* We start out assuming the worst (that the dir is not sane) and
* if it is ok upgrade the status to ``no timestamp file''.
* Note that we don't check the parent(s) of dirparent for
* sanity since the sudo dir is often just located in /tmp.
*/
if (lstat(dirparent, &sb) == 0) {
if (!S_ISDIR(sb.st_mode))
log_error(NO_EXIT, "%s exists but is not a directory (0%o)",
dirparent, (unsigned int) sb.st_mode);
else if (sb.st_uid != timestamp_uid)
log_error(NO_EXIT, "%s owned by uid %u, should be uid %u",
dirparent, (unsigned int) sb.st_uid,
(unsigned int) timestamp_uid);
else if ((sb.st_mode & 0000022))
log_error(NO_EXIT,
"%s writable by non-owner (0%o), should be mode 0700",
dirparent, (unsigned int) sb.st_mode);
else {
if ((sb.st_mode & 0000777) != 0700)
(void) chmod(dirparent, 0700);
status = TS_MISSING;
}
} else if (errno != ENOENT) {
log_error(NO_EXIT|USE_ERRNO, "can't stat %s", dirparent);
} else {
/* No dirparent, try to make one. */
if (ISSET(flags, TS_MAKE_DIRS)) {
if (mkdir(dirparent, S_IRWXU))
log_error(NO_EXIT|USE_ERRNO, "can't mkdir %s",
dirparent);
else
status = TS_MISSING;
}
}
if (status == TS_ERROR)
goto done;
/*
* Sanity check the user's ticket dir. We start by downgrading
* the status to TS_ERROR. If the ticket dir exists and is sane
* this will be upgraded to TS_OLD. If the dir does not exist,
* it will be upgraded to TS_MISSING.
*/
status = TS_ERROR; /* downgrade status again */
if (lstat(timestampdir, &sb) == 0) {
if (!S_ISDIR(sb.st_mode)) {
if (S_ISREG(sb.st_mode)) {
/* convert from old style */
if (unlink(timestampdir) == 0)
status = TS_MISSING;
} else
log_error(NO_EXIT, "%s exists but is not a directory (0%o)",
timestampdir, (unsigned int) sb.st_mode);
} else if (sb.st_uid != timestamp_uid)
log_error(NO_EXIT, "%s owned by uid %u, should be uid %u",
timestampdir, (unsigned int) sb.st_uid,
(unsigned int) timestamp_uid);
else if ((sb.st_mode & 0000022))
log_error(NO_EXIT,
"%s writable by non-owner (0%o), should be mode 0700",
timestampdir, (unsigned int) sb.st_mode);
else {
if ((sb.st_mode & 0000777) != 0700)
(void) chmod(timestampdir, 0700);
status = TS_OLD; /* do date check later */
}
} else if (errno != ENOENT) {
log_error(NO_EXIT|USE_ERRNO, "can't stat %s", timestampdir);
} else
status = TS_MISSING;
/*
* If there is no user ticket dir, AND we are in tty ticket mode,
* AND the TS_MAKE_DIRS flag is set, create the user ticket dir.
*/
if (status == TS_MISSING && timestampfile && ISSET(flags, TS_MAKE_DIRS)) {
if (mkdir(timestampdir, S_IRWXU) == -1) {
status = TS_ERROR;
log_error(NO_EXIT|USE_ERRNO, "can't mkdir %s", timestampdir);
}
}
/*
* Sanity check the tty ticket file if it exists.
*/
if (timestampfile && status != TS_ERROR) {
if (status != TS_MISSING)
status = TS_NOFILE; /* dir there, file missing */
if (def_tty_tickets && !user_ttypath)
goto done; /* no tty, always prompt */
if (lstat(timestampfile, &sb) == 0) {
if (!S_ISREG(sb.st_mode)) {
status = TS_ERROR;
log_error(NO_EXIT, "%s exists but is not a regular file (0%o)",
timestampfile, (unsigned int) sb.st_mode);
} else {
/* If bad uid or file mode, complain and kill the bogus file. */
if (sb.st_uid != timestamp_uid) {
log_error(NO_EXIT,
"%s owned by uid %u, should be uid %u",
timestampfile, (unsigned int) sb.st_uid,
(unsigned int) timestamp_uid);
(void) unlink(timestampfile);
} else if ((sb.st_mode & 0000022)) {
log_error(NO_EXIT,
"%s writable by non-owner (0%o), should be mode 0600",
timestampfile, (unsigned int) sb.st_mode);
(void) unlink(timestampfile);
} else {
/* If not mode 0600, fix it. */
if ((sb.st_mode & 0000777) != 0600)
(void) chmod(timestampfile, 0600);
/*
* Check for stored tty info. If the file is zero-sized
* it is an old-style timestamp with no tty info in it.
* If removing, we don't care about the contents.
* The actual mtime check is done later.
*/
if (ISSET(flags, TS_REMOVE)) {
status = TS_OLD;
} else if (sb.st_size != 0) {
struct tty_info info;
int fd = open(timestampfile, O_RDONLY, 0644);
if (fd != -1) {
if (read(fd, &info, sizeof(info)) == sizeof(info) &&
memcmp(&info, &tty_info, sizeof(info)) == 0) {
status = TS_OLD;
}
close(fd);
}
}
}
}
} else if (errno != ENOENT) {
log_error(NO_EXIT|USE_ERRNO, "can't stat %s", timestampfile);
status = TS_ERROR;
}
}
/*
* If the file/dir exists and we are not removing it, check its mtime.
*/
if (status == TS_OLD && !ISSET(flags, TS_REMOVE)) {
mtim_get(&sb, &mtime);
/* Negative timeouts only expire manually (sudo -k). */
if (def_timestamp_timeout < 0 && mtime.tv_sec != 0)
status = TS_CURRENT;
else {
now = time(NULL);
if (def_timestamp_timeout &&
now - mtime.tv_sec < 60 * def_timestamp_timeout) {
/*
* Check for bogus time on the stampfile. The clock may
* have been set back or someone could be trying to spoof us.
*/
if (mtime.tv_sec > now + 60 * def_timestamp_timeout * 2) {
time_t tv_sec = (time_t)mtime.tv_sec;
log_error(NO_EXIT,
"timestamp too far in the future: %20.20s",
4 + ctime(&tv_sec));
if (timestampfile)
(void) unlink(timestampfile);
else
(void) rmdir(timestampdir);
status = TS_MISSING;
} else if (get_boottime(&boottime) && timevalcmp(&mtime, &boottime, <)) {
status = TS_OLD;
} else {
status = TS_CURRENT;
}
}
}
}
done:
if (timestamp_uid != 0)
restore_perms();
return status;
}
/*
* Remove the timestamp ticket file/dir.
*/
void
remove_timestamp(int remove)
{
struct timeval tv;
char *timestampdir, *timestampfile, *path;
int status;
if (build_timestamp(&timestampdir, &timestampfile) == -1)
return;
status = timestamp_status(timestampdir, timestampfile, user_name,
TS_REMOVE);
if (status != TS_MISSING && status != TS_ERROR) {
path = timestampfile ? timestampfile : timestampdir;
if (remove) {
if (timestampfile)
status = unlink(timestampfile);
else
status = rmdir(timestampdir);
if (status == -1 && errno != ENOENT) {
log_error(NO_EXIT, "can't remove %s (%s), will reset to Epoch",
path, strerror(errno));
remove = FALSE;
}
} else {
timevalclear(&tv);
if (touch(-1, path, &tv) == -1 && errno != ENOENT)
error(1, "can't reset %s to Epoch", path);
}
}
efree(timestampdir);
efree(timestampfile);
}
/*
* Returns TRUE if tty lives on a devpts or /devices filesystem, else FALSE.
* Unlike most filesystems, the ctime of devpts nodes is not updated when
* the device node is written to, only when the inode's status changes,
* typically via the chmod, chown, link, rename, or utimes system calls.
* Since the ctime is "stable" in this case, we can stash it the tty ticket
* file and use it to determine whether the tty ticket file is stale.
*/
static int
tty_is_devpts(const char *tty)
{
int retval = FALSE;
#ifdef __linux__
struct statfs sfs;
#ifndef DEVPTS_SUPER_MAGIC
# define DEVPTS_SUPER_MAGIC 0x1cd1
#endif
if (statfs(tty, &sfs) == 0) {
if (sfs.f_type == DEVPTS_SUPER_MAGIC)
retval = TRUE;
}
#elif defined(__sun) && defined(__SVR4)
struct statvfs sfs;
if (statvfs(tty, &sfs) == 0) {
if (strcmp(sfs.f_fstr, "devices") == 0)
retval = TRUE;
}
#endif /* __linux__ */
return retval;
}
/*
* 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;
if (def_rootpw) {
if ((pw = sudo_getpwuid(0)) == NULL)
log_error(0, "unknown uid: 0");
} else if (def_runaspw) {
if ((pw = sudo_getpwnam(def_runas_default)) == NULL)
log_error(0, "unknown user: %s", def_runas_default);
} else if (def_targetpw) {
if (runas_pw->pw_name == NULL)
log_error(NO_MAIL|MSG_ONLY, "unknown uid: %u",
(unsigned int) runas_pw->pw_uid);
pw_addref(runas_pw);
pw = runas_pw;
} else {
pw_addref(sudo_user.pw);
pw = sudo_user.pw;
}
return pw;
}
Reference in New Issue View Git Blame Copy Permalink