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/* $OpenBSD: skeyaudit.c,v 1.29 2019/06/28 13:35:03 deraadt Exp $ */
/*
* Copyright (c) 1997, 2000, 2003 Todd C. Miller <millert@openbsd.org>
*
* 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 TODD C. MILLER DISCLAIMS ALL
* WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL TODD C. MILLER 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 <sys/wait.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <login_cap.h>
#include <paths.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <skey.h>
void notify(struct passwd *, int, int);
void sanitise_stdfd(void);
FILE *runsendmail(struct passwd *, int *);
__dead void usage(void);
void
sanitise_stdfd(void)
{
int nullfd, dupfd;
if ((nullfd = dupfd = open(_PATH_DEVNULL, O_RDWR)) == -1) {
fprintf(stderr, "Couldn't open /dev/null: %s\n",
strerror(errno));
exit(1);
}
while (++dupfd <= STDERR_FILENO) {
/* Only populate closed fds. */
if (fcntl(dupfd, F_GETFL) == -1 && errno == EBADF) {
if (dup2(nullfd, dupfd) == -1) {
fprintf(stderr, "dup2: %s\n", strerror(errno));
exit(1);
}
}
}
if (nullfd > STDERR_FILENO)
close(nullfd);
}
int
main(int argc, char **argv)
{
struct passwd *pw;
struct skey key;
char *name;
int ch, left, aflag, iflag, limit;
if (pledge("stdio rpath wpath flock getpw proc exec id", NULL) == -1)
err(1, "pledge");
aflag = iflag = 0;
limit = 12;
while ((ch = getopt(argc, argv, "ail:")) != -1)
switch(ch) {
case 'a':
if (getuid() != 0)
errx(1, "only root may use the -a flag");
aflag = 1;
break;
case 'i':
iflag = 1;
break;
case 'l':
errno = 0;
if ((limit = (int)strtol(optarg, NULL, 10)) == 0)
errno = ERANGE;
if (errno) {
warn("key limit");
usage();
}
break;
default:
usage();
}
if (iflag) {
if (pledge("stdio rpath wpath flock getpw", NULL) == -1)
err(1, "pledge");
}
/* If we are in interactive mode, STDOUT_FILENO *must* be open. */
if (iflag && fcntl(STDOUT_FILENO, F_GETFL) == -1 && errno == EBADF)
exit(1);
/*
* Make sure STDIN_FILENO, STDOUT_FILENO, and STDERR_FILENO are open.
* If not, open /dev/null in their place or bail.
*/
sanitise_stdfd();
if (argc - optind > 0)
usage();
/* Need key.keyfile zero'd at the very least */
(void)memset(&key, 0, sizeof(key));
left = 0;
if (aflag) {
while ((ch = skeygetnext(&key)) == 0) {
left = key.n - 1;
if ((pw = getpwnam(key.logname)) == NULL)
continue;
if (left >= limit)
continue;
(void)fclose(key.keyfile);
key.keyfile = NULL;
notify(pw, left, iflag);
}
if (ch == -1)
errx(-1, "cannot open %s", _PATH_SKEYDIR);
} else {
if ((pw = getpwuid(getuid())) == NULL)
errx(1, "no passwd entry for uid %u", getuid());
if ((name = strdup(pw->pw_name)) == NULL)
err(1, "cannot allocate memory");
sevenbit(name);
switch (skeylookup(&key, name)) {
case 0: /* Success! */
left = key.n - 1;
break;
case -1: /* File error */
errx(1, "cannot open %s/%s", _PATH_SKEYDIR,
name);
break;
case 1: /* Unknown user */
errx(1, "user %s is not listed in %s", name,
_PATH_SKEYDIR);
}
(void)fclose(key.keyfile);
if (left < limit)
notify(pw, left, iflag);
}
exit(0);
}
void
notify(struct passwd *pw, int seq, int interactive)
{
static char hostname[HOST_NAME_MAX+1];
pid_t pid;
FILE *out;
/* Only set this once */
if (hostname[0] == '\0' && gethostname(hostname, sizeof(hostname)) == -1)
strlcpy(hostname, "unknown", sizeof(hostname));
if (interactive)
out = stdout;
else
out = runsendmail(pw, &pid);
if (!interactive)
(void)fprintf(out,
"Auto-Submitted: auto-generated\n"
"To: %s\nSubject: IMPORTANT action required\n", pw->pw_name);
if (seq)
(void)fprintf(out,
"\nYou are nearing the end of your current S/Key sequence for account\n\
%s on system %s.\n\n\
Your S/Key sequence number is now %d. When it reaches zero\n\
you will no longer be able to use S/Key to log into the system.\n\n",
pw->pw_name, hostname, seq);
else
(void)fprintf(out,
"\nYou are at the end of your current S/Key sequence for account\n\
%s on system %s.\n\n\
At this point you can no longer use S/Key to log into the system.\n\n",
pw->pw_name, hostname);
(void)fprintf(out,
"Type \"skeyinit -s\" to reinitialize your sequence number.\n\n");
if (!interactive) {
(void)fclose(out);
(void)waitpid(pid, NULL, 0);
}
}
FILE *
runsendmail(struct passwd *pw, pid_t *pidp)
{
FILE *fp;
int pfd[2];
pid_t pid;
if (pipe(pfd) == -1)
return(NULL);
switch (pid = fork()) {
case -1: /* fork(2) failed */
(void)close(pfd[0]);
(void)close(pfd[1]);
return(NULL);
case 0: /* In child */
(void)close(pfd[1]);
(void)dup2(pfd[0], STDIN_FILENO);
(void)close(pfd[0]);
/* Run sendmail as target user not root */
if (getuid() == 0 &&
setusercontext(NULL, pw, pw->pw_uid, LOGIN_SETALL) != 0) {
warn("cannot set user context");
_exit(127);
}
execl(_PATH_SENDMAIL, "sendmail", "-t", (char *)NULL);
warn("cannot run \"%s -t\"", _PATH_SENDMAIL);
_exit(127);
}
/* In parent */
*pidp = pid;
fp = fdopen(pfd[1], "w");
(void)close(pfd[0]);
return(fp);
}
__dead void
usage(void)
{
extern char *__progname;
(void)fprintf(stderr, "usage: %s [-ai] [-l limit]\n",
__progname);
exit(1);
}
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