busybox/loginutils/passwd.c

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/* vi: set sw=4 ts=4: */
/*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
#include "busybox.h"
#include <syslog.h>
static void nuke_str(char *str)
{
if (str) memset(str, 0, strlen(str));
}
static int i64c(int i)
{
i &= 0x3f;
if (i == 0)
return '.';
if (i == 1)
return '/';
if (i < 12)
return ('0' - 2 + i);
if (i < 38)
return ('A' - 12 + i);
return ('a' - 38 + i);
}
static void crypt_make_salt(char *p, int cnt)
{
unsigned x = x; /* it's pointless to initialize it anyway :) */
x += getpid() + time(NULL) + clock();
do {
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/* x = (x*1664525 + 1013904223) % 2^32 generator is lame
* (low-order bit is not "random", etc...),
* but for our purposes it is good enough */
x = x*1664525 + 1013904223;
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/* BTW, Park and Miller's "minimal standard generator" is
* x = x*16807 % ((2^31)-1)
* It has no problem with visibly alternating lowest bit
* but is also weak in cryptographic sense + needs div,
* which needs more code (and slower) on many CPUs */
*p++ = i64c(x >> 16);
*p++ = i64c(x >> 22);
} while (--cnt);
*p = '\0';
}
static char* new_password(const struct passwd *pw, uid_t myuid, int algo)
{
char salt[sizeof("$N$XXXXXXXX")]; /* "$N$XXXXXXXX" or "XX" */
char *orig = (char*)"";
char *newp = NULL;
char *cipher = NULL;
char *cp = NULL;
char *ret = NULL; /* failure so far */
if (myuid && pw->pw_passwd[0]) {
orig = bb_askpass(0, "Old password:"); /* returns ptr to static */
if (!orig)
goto err_ret;
cipher = pw_encrypt(orig, pw->pw_passwd); /* returns ptr to static */
if (strcmp(cipher, pw->pw_passwd) != 0) {
syslog(LOG_WARNING, "incorrect password for '%s'",
pw->pw_name);
bb_do_delay(FAIL_DELAY);
puts("Incorrect password");
goto err_ret;
}
}
orig = xstrdup(orig); /* or else bb_askpass() will destroy it */
newp = bb_askpass(0, "New password:"); /* returns ptr to static */
if (!newp)
goto err_ret;
newp = xstrdup(newp); /* we are going to bb_askpass() again, so save it */
if (ENABLE_FEATURE_PASSWD_WEAK_CHECK
&& obscure(orig, newp, pw) && myuid)
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goto err_ret; /* non-root is not allowed to have weak passwd */
cp = bb_askpass(0, "Retype password:");
if (!cp)
goto err_ret;
if (strcmp(cp, newp)) {
puts("Passwords don't match");
goto err_ret;
}
/*memset(salt, 0, sizeof(salt)); - why?*/
crypt_make_salt(salt, 1); /* des */
if (algo) { /* MD5 */
strcpy(salt, "$1$");
crypt_make_salt(salt + 3, 4);
}
ret = xstrdup(pw_encrypt(newp, salt)); /* returns ptr to static */
/* whee, success! */
err_ret:
nuke_str(orig);
if (ENABLE_FEATURE_CLEAN_UP) free(orig);
nuke_str(newp);
if (ENABLE_FEATURE_CLEAN_UP) free(newp);
nuke_str(cipher);
nuke_str(cp);
return ret;
}
#if 0
static int get_algo(char *a)
{
/* standard: MD5 */
int x = 1;
if (strcasecmp(a, "des") == 0)
x = 0;
return x;
}
#endif
static int update_passwd(const char *filename, const char *username,
const char *new_pw)
{
struct stat sb;
struct flock lock;
FILE *old_fp;
FILE *new_fp;
char *new_name;
char *last_char;
unsigned user_len;
int old_fd;
int new_fd;
int i;
int ret = 1; /* failure */
logmode = LOGMODE_STDIO;
/* New passwd file, "/etc/passwd+" for now */
new_name = xasprintf("%s+", filename);
last_char = &new_name[strlen(new_name)-1];
username = xasprintf("%s:", username);
user_len = strlen(username);
old_fp = fopen(filename, "r+");
if (!old_fp)
goto free_mem;
old_fd = fileno(old_fp);
/* Try to create "/etc/passwd+". Wait if it exists. */
i = 30;
do {
// FIXME: on last iteration try w/o O_EXCL but with O_TRUNC?
new_fd = open(new_name, O_WRONLY|O_CREAT|O_EXCL,0600);
if (new_fd >= 0) goto created;
if (errno != EEXIST) break;
usleep(100000); /* 0.1 sec */
} while (--i);
bb_perror_msg("cannot create '%s'", new_name);
goto close_old_fp;
created:
if (!fstat(old_fd, &sb)) {
fchmod(new_fd, sb.st_mode & 0777); /* ignore errors */
fchown(new_fd, sb.st_uid, sb.st_gid);
}
new_fp = fdopen(new_fd, "w");
if (!new_fp) {
close(new_fd);
goto unlink_new;
}
/* Backup file is "/etc/passwd-" */
last_char[0] = '-';
/* Delete old one, create new as a hardlink to current */
i = (unlink(new_name) && errno != ENOENT);
if (i || link(filename, new_name))
bb_perror_msg("warning: cannot create backup copy '%s'", new_name);
last_char[0] = '+';
/* Lock the password file before updating */
lock.l_type = F_WRLCK;
lock.l_whence = SEEK_SET;
lock.l_start = 0;
lock.l_len = 0;
if (fcntl(old_fd, F_SETLK, &lock) < 0)
bb_perror_msg("warning: cannot lock '%s'", filename);
lock.l_type = F_UNLCK;
/* Read current password file, write updated one */
while (1) {
char *line = xmalloc_fgets(old_fp);
if (!line) break; /* EOF/error */
if (strncmp(username, line, user_len) == 0) {
/* we have a match with "username:"... */
const char *cp = line + user_len;
/* now cp -> old passwd, skip it: */
cp = strchr(cp, ':');
if (!cp) cp = "";
/* now cp -> ':' after old passwd or -> "" */
fprintf(new_fp, "%s%s%s", username, new_pw, cp);
/* Erase password in memory */
} else
fputs(line, new_fp);
free(line);
}
fcntl(old_fd, F_SETLK, &lock);
/* We do want all of them to execute, thus | instead of || */
if ((ferror(old_fp) | fflush(new_fp) | fsync(new_fd) | fclose(new_fp))
|| rename(new_name, filename)
) {
/* At least one of those failed */
goto unlink_new;
}
ret = 0; /* whee, success! */
unlink_new:
if (ret) unlink(new_name);
close_old_fp:
fclose(old_fp);
free_mem:
if (ENABLE_FEATURE_CLEAN_UP) free(new_name);
if (ENABLE_FEATURE_CLEAN_UP) free((char*)username);
logmode = LOGMODE_BOTH;
return ret;
}
int passwd_main(int argc, char **argv);
int passwd_main(int argc, char **argv)
{
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enum {
OPT_algo = 0x1, /* -a - password algorithm */
OPT_lock = 0x2, /* -l - lock account */
OPT_unlock = 0x4, /* -u - unlock account */
OPT_delete = 0x8, /* -d - delete password */
OPT_lud = 0xe,
STATE_ALGO_md5 = 0x10,
/*STATE_ALGO_des = 0x20, not needed yet */
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};
unsigned opt;
const char *opt_a = "";
const char *filename;
char *myname;
char *name;
char *newp;
struct passwd *pw;
uid_t myuid;
struct rlimit rlimit_fsize;
char c;
logmode = LOGMODE_BOTH;
openlog(applet_name, LOG_NOWAIT, LOG_AUTH);
opt = getopt32(argc, argv, "a:lud", &opt_a);
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argc -= optind;
argv += optind;
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if (strcasecmp(opt_a, "des") != 0) /* -a */
opt |= STATE_ALGO_md5;
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//else
// opt |= STATE_ALGO_des;
myuid = getuid();
if ((opt & OPT_lud) && (!argc || myuid))
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bb_show_usage();
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myname = xstrdup(bb_getpwuid(NULL, myuid, -1));
name = argc ? argv[0] : myname;
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pw = getpwnam(name);
if (!pw) bb_error_msg_and_die("unknown user %s", name);
if (myuid && pw->pw_uid != myuid) {
/* LOGMODE_BOTH */
bb_error_msg_and_die("%s can't change password for %s", myname, name);
}
filename = bb_path_passwd_file;
#if ENABLE_FEATURE_SHADOWPASSWDS
{
struct spwd *sp = getspnam(name);
if (!sp) {
/* LOGMODE_BOTH */
bb_error_msg("no record of %s in %s, using %s",
name, bb_path_shadow_file,
bb_path_passwd_file);
} else {
filename = bb_path_shadow_file;
pw->pw_passwd = sp->sp_pwdp;
}
}
#endif
/* Decide what the new password will be */
newp = NULL;
c = pw->pw_passwd[0] - '!';
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if (!(opt & OPT_lud)) {
if (myuid && !c) { /* passwd starts with '!' */
/* LOGMODE_BOTH */
bb_error_msg_and_die("cannot change "
"locked password for %s", name);
}
printf("Changing password for %s\n", name);
newp = new_password(pw, myuid, opt & STATE_ALGO_md5);
if (!newp) {
logmode = LOGMODE_STDIO;
bb_error_msg_and_die("password for %s is unchanged", name);
}
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} else if (opt & OPT_lock) {
if (!c) goto skip; /* passwd starts with '!' */
newp = xasprintf("!%s", pw->pw_passwd);
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} else if (opt & OPT_unlock) {
if (c) goto skip; /* not '!' */
newp = xstrdup(&pw->pw_passwd[1]);
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} else if (opt & OPT_delete) {
newp = xstrdup("");
}
rlimit_fsize.rlim_cur = rlimit_fsize.rlim_max = 512L * 30000;
setrlimit(RLIMIT_FSIZE, &rlimit_fsize);
signal(SIGHUP, SIG_IGN);
signal(SIGINT, SIG_IGN);
signal(SIGQUIT, SIG_IGN);
umask(077);
xsetuid(0);
if (update_passwd(filename, name, newp) != 0) {
/* LOGMODE_BOTH */
bb_error_msg_and_die("cannot update password file %s",
filename);
}
/* LOGMODE_BOTH */
bb_info_msg("Password for %s changed by %s", name, myname);
if (ENABLE_FEATURE_CLEAN_UP) free(newp);
skip:
if (!newp) {
bb_error_msg_and_die("password for %s is already %slocked",
name, (opt & OPT_unlock) ? "un" : "");
}
if (ENABLE_FEATURE_CLEAN_UP) free(myname);
return 0;
}