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passwd: rework:

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* do not make backup copy by copying (just retain old file)
* correctly fall back to /etc/passwd if user is not in shadow
* fix bug with overlong passwd entries
* be permissive on some kinds of failures
* reduce stack usage
* code size: -500 bytes
This commit is contained in:
Denis Vlasenko
2006-11-30 16:41:15 +00:00
parent b8bb27c7ea
commit ab24e18c7a
5 changed files with 288 additions and 320 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
editors/patch.c
View File

@ -117,12 +117,14 @@ int patch_main(int argc, char **argv)
free(patch_line);
patch_line = xmalloc_fgets(patch_file);
}
/* FIXME: patch_line NULL check?? */
/* Extract the filename used before the patch was generated */
original_filename = extract_filename(patch_line, patch_level);
free(patch_line);
patch_line = xmalloc_fgets(patch_file);
/* FIXME: NULL check?? */
if (strncmp(patch_line, "+++ ", 4) != 0) {
ret = 2;
bb_error_msg("invalid patch");

2
libbb/bb_askpass.c
View File

@ -60,7 +60,7 @@ char *bb_askpass(int timeout, const char * prompt)
(read did not overwrite it) */
do {
if (passwd[i] == '\r' || passwd[i] == '\n')
passwd[i] = 0;
passwd[i] = '\0';
} while (passwd[i++]);
}

14
libbb/get_line_from_file.c
View File

@ -9,11 +9,9 @@
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
#include <stdio.h>
#include <stdlib.h>
#include "libbb.h"
/* get_line_from_file() - This function reads an entire line from a text file,
/* This function reads an entire line from a text file,
* up to a newline or NUL byte. It returns a malloc'ed char * which must be
* stored and free'ed by the caller. If end is null '\n' isn't considered
* end of line. If end isn't null, length of the chunk read is stored in it. */
@ -37,10 +35,12 @@ char *bb_get_chunk_from_file(FILE * file, int *end)
if (end)
*end = idx;
if (linebuf) {
if (ferror(file)) {
free(linebuf);
return NULL;
}
// huh, is fgets discards prior data on error like this?
// I don't think so....
//if (ferror(file)) {
// free(linebuf);
// return NULL;
//}
linebuf = xrealloc(linebuf, idx+1);
linebuf[idx] = 0;
}

10
libbb/obscure.c
View File

@ -157,14 +157,14 @@ static const char *obscure_msg(const char *old_p, const char *new_p, const struc
return NULL;
}
int obscure(const char *old, const char *newval, const struct passwd *pwdp)
int obscure(const char *old, const char *newval, const struct passwd *pw)
{
const char *msg;
if ((msg = obscure_msg(old, newval, pwdp))) {
printf("Bad password: %s.\n", msg);
/* If user is root warn only */
return getuid() ? 1 : 0;
msg = obscure_msg(old, newval, pw);
if (msg) {
printf("Bad password: %s\n", msg);
return 1;
}
return 0;
}

580
loginutils/passwd.c
View File

@ -6,258 +6,13 @@
#include "busybox.h"
#include <syslog.h>
static char crypt_passwd[128];
static int create_backup(const char *backup, FILE * fp);
static int new_password(const struct passwd *pw, int amroot, int algo);
static void set_filesize_limit(int blocks);
static int get_algo(char *a)
static void nuke_str(char *str)
{
int x = 1; /* standard: MD5 */
if (strcasecmp(a, "des") == 0)
x = 0;
return x;
if (str) memset(str, 0, strlen(str));
}
static int update_passwd(const struct passwd *pw, const char *crypt_pw)
{
char filename[1024];
char buf[1025];
char buffer[80];
char username[32];
char *pw_rest;
int mask;
int continued;
FILE *fp;
FILE *out_fp;
struct stat sb;
struct flock lock;
#if ENABLE_FEATURE_SHADOWPASSWDS
if (access(bb_path_shadow_file, F_OK) == 0) {
snprintf(filename, sizeof filename, "%s", bb_path_shadow_file);
} else
#endif
{
snprintf(filename, sizeof filename, "%s", bb_path_passwd_file);
}
fp = fopen(filename, "r+");
if (fp == 0 || fstat(fileno(fp), &sb)) {
/* return 0; */
return 1;
}
/* 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(fileno(fp), F_SETLK, &lock) < 0) {
bb_perror_msg("%s", filename);
return 1;
}
lock.l_type = F_UNLCK;
snprintf(buf, sizeof buf, "%s-", filename);
if (create_backup(buf, fp)) {
fcntl(fileno(fp), F_SETLK, &lock);
fclose(fp);
return 1;
}
snprintf(buf, sizeof buf, "%s+", filename);
mask = umask(0777);
out_fp = fopen(buf, "w");
umask(mask);
if ((!out_fp) || (fchmod(fileno(out_fp), sb.st_mode & 0777))
|| (fchown(fileno(out_fp), sb.st_uid, sb.st_gid))) {
fcntl(fileno(fp), F_SETLK, &lock);
fclose(fp);
fclose(out_fp);
return 1;
}
continued = 0;
snprintf(username, sizeof username, "%s:", pw->pw_name);
rewind(fp);
while (!feof(fp)) {
fgets(buffer, sizeof buffer, fp);
if (!continued) { /* Check to see if we're updating this line. */
if (strncmp(username, buffer, strlen(username)) == 0) {
/* we have a match. */
pw_rest = strchr(buffer, ':');
*pw_rest++ = '\0';
pw_rest = strchr(pw_rest, ':');
fprintf(out_fp, "%s:%s%s", buffer, crypt_pw, pw_rest);
} else {
fputs(buffer, out_fp);
}
} else {
fputs(buffer, out_fp);
}
if (buffer[strlen(buffer) - 1] == '\n') {
continued = 0;
} else {
continued = 1;
}
memset(buffer, 0, sizeof buffer);
}
if (fflush(out_fp) || fsync(fileno(out_fp)) || fclose(out_fp)) {
unlink(buf);
fcntl(fileno(fp), F_SETLK, &lock);
fclose(fp);
return 1;
}
if (rename(buf, filename) < 0) {
fcntl(fileno(fp), F_SETLK, &lock);
fclose(fp);
return 1;
} else {
fcntl(fileno(fp), F_SETLK, &lock);
fclose(fp);
return 0;
}
}
int passwd_main(int argc, char **argv)
{
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,
};
unsigned opt;
char *opt_a;
int amroot;
char *cp;
char *np;
char *name;
char *myname;
int algo = 1;
const struct passwd *pw;
amroot = (getuid() == 0);
openlog("passwd", LOG_PID | LOG_CONS | LOG_NOWAIT, LOG_AUTH);
opt = getopt32(argc, argv, "a:lud", &opt_a);
argc -= optind;
argv += optind;
if (opt & OPT_algo) algo = get_algo(opt_a); // -a
if ((opt & OPT_lud) && (!argc || !amroot))
bb_show_usage();
myname = xstrdup(bb_getpwuid(NULL, getuid(), -1));
name = myname;
if (argc) name = argv[0];
pw = getpwnam(name);
if (!pw) {
bb_error_msg_and_die("unknown user %s", name);
}
if (!amroot && pw->pw_uid != getuid()) {
syslog(LOG_WARNING, "can't change pwd for '%s'", name);
bb_error_msg_and_die("permission denied");
}
if (ENABLE_FEATURE_SHADOWPASSWDS) {
struct spwd *sp = getspnam(name);
if (!sp) bb_error_msg_and_die("unknown user %s", name);
cp = sp->sp_pwdp;
} else cp = pw->pw_passwd;
np = name;
safe_strncpy(crypt_passwd, cp, sizeof(crypt_passwd));
if (!(opt & OPT_lud)) {
if (!amroot) {
if (cp[0] == '!') {
syslog(LOG_WARNING, "password locked for '%s'", np);
bb_error_msg_and_die("the password for %s cannot be changed", np);
}
}
printf("Changing password for %s\n", name);
if (new_password(pw, amroot, algo)) {
bb_error_msg_and_die("the password for %s is unchanged", name);
}
} else if (opt & OPT_lock) {
if (crypt_passwd[0] != '!') {
memmove(&crypt_passwd[1], crypt_passwd,
sizeof crypt_passwd - 1);
crypt_passwd[sizeof crypt_passwd - 1] = '\0';
crypt_passwd[0] = '!';
}
} else if (opt & OPT_unlock) {
if (crypt_passwd[0] == '!') {
memmove(crypt_passwd, &crypt_passwd[1],
sizeof crypt_passwd - 1);
}
} else if (opt & OPT_delete) {
crypt_passwd[0] = '\0';
}
set_filesize_limit(30000);
signal(SIGHUP, SIG_IGN);
signal(SIGINT, SIG_IGN);
signal(SIGQUIT, SIG_IGN);
umask(077);
xsetuid(0);
if (!update_passwd(pw, crypt_passwd)) {
syslog(LOG_INFO, "password for '%s' changed by user '%s'", name,
myname);
puts("Password changed");
} else {
syslog(LOG_WARNING, "cannot update password file");
bb_error_msg_and_die("cannot update password file");
}
if (ENABLE_FEATURE_CLEAN_UP) free(myname);
return 0;
}
static int create_backup(const char *backup, FILE * fp)
{
struct stat sb;
struct utimbuf ub;
FILE *bkfp;
int c, mask;
if (fstat(fileno(fp), &sb))
/* return -1; */
return 1;
mask = umask(077);
bkfp = fopen(backup, "w");
umask(mask);
if (!bkfp)
/* return -1; */
return 1;
/* TODO: faster copy, not one-char-at-a-time. --marekm */
rewind(fp);
while ((c = getc(fp)) != EOF) {
if (putc(c, bkfp) == EOF)
break;
}
if (c != EOF || fflush(bkfp)) {
fclose(bkfp);
/* return -1; */
return 1;
}
if (fclose(bkfp))
/* return -1; */
return 1;
ub.actime = sb.st_atime;
ub.modtime = sb.st_mtime;
utime(backup, &ub);
return 0;
}
static int i64c(int i)
{
if (i <= 0)
@ -273,6 +28,7 @@ static int i64c(int i)
return 'z';
}
static char *crypt_make_salt(void)
{
time_t now;
@ -288,85 +44,72 @@ static char *crypt_make_salt(void)
}
static int new_password(const struct passwd *pw, int amroot, int algo)
static char* new_password(const struct passwd *pw, const char *old_crypted,
uid_t myuid, int algo)
{
char *clear;
char *cipher;
char *cp;
char salt[12]; /* "$N$XXXXXXXX" or "XX" */
char orig[200];
char pass[200];
char salt[sizeof("$N$XXXXXXXX")]; /* "$N$XXXXXXXX" or "XX" */
char *orig = "";
char *newp = NULL;
char *cipher = NULL;
char *cp = NULL;
char *ret = NULL; /* failure so far */
if (!amroot && crypt_passwd[0]) {
clear = bb_askpass(0, "Old password:");
if (!clear) {
/* return -1; */
return 1;
}
cipher = pw_encrypt(clear, crypt_passwd);
if (strcmp(cipher, crypt_passwd) != 0) {
if (myuid && old_crypted[0]) {
orig = bb_askpass(0, "Old password:"); /* returns ptr to static */
if (!orig)
goto err_ret;
cipher = pw_encrypt(orig, old_crypted); /* returns ptr to static */
if (strcmp(cipher, old_crypted) != 0) {
syslog(LOG_WARNING, "incorrect password for '%s'",
pw->pw_name);
pw->pw_name);
bb_do_delay(FAIL_DELAY);
puts("Incorrect password");
/* return -1; */
return 1;
goto err_ret;
}
safe_strncpy(orig, clear, sizeof(orig));
memset(clear, 0, strlen(clear));
memset(cipher, 0, strlen(cipher));
} else {
orig[0] = '\0';
}
cp = bb_askpass(0, "Enter the new password (minimum of 5 characters).\n"
orig = xstrdup(orig); /* or else bb_askpass() will destroy it */
newp = bb_askpass(0, "Enter the new password (minimum of 5 characters).\n"
"Please use a combination of upper and lower case letters and numbers.\n"
"Enter new password: ");
if (!cp ) {
memset(orig, 0, sizeof orig);
/* return -1; */
return 1;
"Enter 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 (obscure(orig, newp, pw)) {
if (myuid)
goto err_ret; /* non-root is not allowed to have weak passwd */
puts("\nWarning: weak password (continuing)");
}
safe_strncpy(pass, cp, sizeof(pass));
memset(cp, 0, strlen(cp));
/* if (!obscure(orig, pass, pw)) { */
if (obscure(orig, pass, pw)) {
if (amroot) {
puts("\nWarning: weak password (continuing)");
} else {
/* return -1; */
return 1;
}
}
cp = bb_askpass(0, "Re-enter new password: ");
if (!cp) {
memset(orig, 0, sizeof orig);
/* return -1; */
return 1;
}
if (strcmp(cp, pass)) {
puts("Passwords do not match");
/* return -1; */
return 1;
}
memset(cp, 0, strlen(cp));
memset(orig, 0, sizeof(orig));
memset(salt, 0, sizeof(salt));
if (algo == 1) {
cp = bb_askpass(0, "Re-enter new password:");
if (!cp)
goto err_ret;
if (strcmp(cp, newp)) {
puts("Passwords do not match");
goto err_ret;
}
memset(salt, 0, sizeof(salt));
if (algo == 1) { /* MD5 */
strcpy(salt, "$1$");
strcat(salt, crypt_make_salt());
strcat(salt, crypt_make_salt());
strcat(salt, crypt_make_salt());
}
strcat(salt, crypt_make_salt());
cp = pw_encrypt(pass, salt);
ret = xstrdup(pw_encrypt(newp, salt)); /* returns ptr to static */
/* whee, success! */
memset(pass, 0, sizeof pass);
safe_strncpy(crypt_passwd, cp, sizeof(crypt_passwd));
return 0;
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;
}
static void set_filesize_limit(int blocks)
{
struct rlimit rlimit_fsize;
@ -374,3 +117,226 @@ static void set_filesize_limit(int blocks)
rlimit_fsize.rlim_cur = rlimit_fsize.rlim_max = 512L * blocks;
setrlimit(RLIMIT_FSIZE, &rlimit_fsize);
}
#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 */
/* 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);
return ret;
}
int passwd_main(int argc, char **argv)
{
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,
};
unsigned opt;
char *opt_a = "";
const char *filename;
char *myname;
char *name;
char *oldp;
char *newp = NULL; /* gcc happiness */
const struct passwd *pw;
uid_t myuid;
openlog("passwd", LOG_NOWAIT, LOG_AUTH);
opt = getopt32(argc, argv, "a:lud", &opt_a);
argc -= optind;
argv += optind;
if (strcasecmp(opt_a, "des") == 0) /* -a */
opt |= STATE_ALGO_des;
else
opt |= STATE_ALGO_md5;
myuid = getuid();
if ((opt & OPT_lud) && (!argc || myuid))
bb_show_usage();
myname = xstrdup(bb_getpwuid(NULL, myuid, -1));
name = myname;
if (argc) name = argv[0];
pw = getpwnam(name);
if (!pw) bb_error_msg_and_die("unknown user %s", name);
if (myuid && pw->pw_uid != myuid) {
syslog(LOG_WARNING, "can't change pwd for '%s'", name);
bb_error_msg_and_die("permission denied");
}
filename = bb_path_passwd_file;
oldp = pw->pw_passwd;
if (ENABLE_FEATURE_SHADOWPASSWDS) {
struct spwd *sp = getspnam(name);
if (!sp) {
bb_error_msg("no shadow record for user %s found, "
"changing ordinary password instead", name);
} else {
filename = bb_path_shadow_file;
oldp = sp->sp_pwdp;
}
}
/* Decide what the new password will be */
if (!(opt & OPT_lud)) {
if (myuid) {
if (oldp[0] == '!') {
syslog(LOG_WARNING, "password locked for '%s'", name);
bb_error_msg_and_die("the password for %s cannot be changed", name);
}
}
printf("Changing password for %s\n", name);
newp = new_password(pw, oldp,
myuid,
opt & STATE_ALGO_md5);
if (!newp) {
bb_error_msg_and_die("the password for %s is unchanged", name);
}
} else if (opt & OPT_lock) {
if (oldp[0] == '!') goto skip;
newp = xasprintf("!%s", oldp);
} else if (opt & OPT_unlock) {
if (oldp[0] != '!') goto skip;
newp = xstrdup(oldp + 1);
} else if (opt & OPT_delete) {
newp = xstrdup("");
}
set_filesize_limit(30000);
signal(SIGHUP, SIG_IGN);
signal(SIGINT, SIG_IGN);
signal(SIGQUIT, SIG_IGN);
umask(077);
xsetuid(0);
if (update_passwd(filename, name, newp) == 0) {
syslog(LOG_INFO, "password for '%s' changed by user '%s'", name,
myname);
puts("Password changed");
} else {
syslog(LOG_WARNING, "cannot update password file");
bb_error_msg_and_die("cannot update password file");
}
if (ENABLE_FEATURE_CLEAN_UP) free(newp);
skip:
if (ENABLE_FEATURE_CLEAN_UP) free(myname);
return 0;
}