ab24e18c7

Denis Vlasenko

2006-11-30

FAILED Duration: 3s

Subject

passwd: rework: * 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

Binary

No binary (build failed)

Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

—

Build Log

(log yok)

Commit Diff GitHub →

editors/patch.c +2 -0 libbb/bb_askpass.c +1 -1 libbb/get_line_from_file.c +7 -7 libbb/obscure.c +5 -5 loginutils/passwd.c +249 -283

editors/patch.c+2 -0

@@ -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");

libbb/bb_askpass.c+1 -1

@@ -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++]);
	}

libbb/get_line_from_file.c+7 -7

@@ -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;
	}

libbb/obscure.c+5 -5

@@ -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;
	}

loginutils/passwd.c+249 -283

@@ -6,122 +6,234 @@
	#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 void nuke_str(char *str)
+	{
+	if (str) memset(str, 0, strlen(str));
+	}


-	static int get_algo(char *a)
+	static int i64c(int i)
	{
-	int x = 1; /* standard: MD5 */
+	if (i <= 0)
+	return '.';
+	if (i == 1)
+	return '/';
+	if (i >= 2 && i < 12)
+	return ('0' - 2 + i);
+	if (i >= 12 && i < 38)
+	return ('A' - 12 + i);
+	if (i >= 38 && i < 63)
+	return ('a' - 38 + i);
+	return 'z';
+	}
+

+	static char *crypt_make_salt(void)
+	{
+	time_t now;
+	static unsigned long x;
+	static char result[3];
+
+	time(&now);
+	x += now + getpid() + clock();
+	result[0] = i64c(((x >> 18) ^ (x >> 6)) & 077);
+	result[1] = i64c(((x >> 12) ^ x) & 077);
+	result[2] = '\0';
+	return result;
+	}
+
+
+	static char* new_password(const struct passwd pw, const char old_crypted,
+	uid_t myuid, int algo)
+	{
+	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 (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);
+	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, "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:"); /* 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)");
+	}
+
+	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());
+	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;
+	}
+
+
+	static void set_filesize_limit(int blocks)
+	{
+	struct rlimit rlimit_fsize;
+
+	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 struct passwd pw, const char crypt_pw)
+	static int update_passwd(const char filename, const char username,
+	const char *new_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);
+	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);
	}
-
-	fp = fopen(filename, "r+");
-	if (fp == 0 \|\| fstat(fileno(fp), &sb)) {
-	/* return 0; */
-	return 1;
+	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(fileno(fp), F_SETLK, &lock) < 0) {
-	bb_perror_msg("%s", filename);
-	return 1;
-	}
+	if (fcntl(old_fd, F_SETLK, &lock) < 0)
+	bb_perror_msg("warning: cannot lock '%s'", filename);
	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;
+	/* 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);
	}
-	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;
+	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! */

-	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);
-	}
+	unlink_new:
+	if (ret) unlink(new_name);

-	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;
-	}
+	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;
	}


@@ -133,79 +245,88 @@ int passwd_main(int argc, char **argv)
	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;
-	int amroot;
-	char *cp;
-	char *np;
-	char *name;
+	char *opt_a = "";
+	const char *filename;
	char *myname;
-	int algo = 1;
+	char *name;
+	char *oldp;
+	char newp = NULL; / gcc happiness */
	const struct passwd *pw;
+	uid_t myuid;

-	amroot = (getuid() == 0);
-	openlog("passwd", LOG_PID \| LOG_CONS \| LOG_NOWAIT, LOG_AUTH);
+	openlog("passwd", 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))
+
+	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, getuid(), -1));
+	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 (!amroot && pw->pw_uid != getuid()) {
+	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_and_die("unknown user %s", name);
-	cp = sp->sp_pwdp;
-	} else cp = pw->pw_passwd;
+	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;
+	}
+	}

-	np = name;
-	safe_strncpy(crypt_passwd, cp, sizeof(crypt_passwd));
+	/* Decide what the new password will be */
	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);
+	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);
-	if (new_password(pw, amroot, algo)) {
+	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 (crypt_passwd[0] != '!') {
-	memmove(&crypt_passwd[1], crypt_passwd,
-	sizeof crypt_passwd - 1);
-	crypt_passwd[sizeof crypt_passwd - 1] = '\0';
-	crypt_passwd[0] = '!';
-	}
+	if (oldp[0] == '!') goto skip;
+	newp = xasprintf("!%s", oldp);
	} else if (opt & OPT_unlock) {
-	if (crypt_passwd[0] == '!') {
-	memmove(crypt_passwd, &crypt_passwd[1],
-	sizeof crypt_passwd - 1);
-	}
+	if (oldp[0] != '!') goto skip;
+	newp = xstrdup(oldp + 1);
	} else if (opt & OPT_delete) {
-	crypt_passwd[0] = '\0';
+	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(pw, crypt_passwd)) {
+	if (update_passwd(filename, name, newp) == 0) {
	syslog(LOG_INFO, "password for '%s' changed by user '%s'", name,
	myname);
	puts("Password changed");
@@ -213,164 +334,9 @@ int passwd_main(int argc, char **argv)
	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)
-	return '.';
-	if (i == 1)
-	return '/';
-	if (i >= 2 && i < 12)
-	return ('0' - 2 + i);
-	if (i >= 12 && i < 38)
-	return ('A' - 12 + i);
-	if (i >= 38 && i < 63)
-	return ('a' - 38 + i);
-	return 'z';
-	}
-
-	static char *crypt_make_salt(void)
-	{
-	time_t now;
-	static unsigned long x;
-	static char result[3];
-
-	time(&now);
-	x += now + getpid() + clock();
-	result[0] = i64c(((x >> 18) ^ (x >> 6)) & 077);
-	result[1] = i64c(((x >> 12) ^ x) & 077);
-	result[2] = '\0';
-	return result;
-	}
-
-
-	static int new_password(const struct passwd *pw, int amroot, int algo)
-	{
-	char *clear;
-	char *cipher;
-	char *cp;
-	char salt[12]; /* "$N$XXXXXXXX" or "XX" */
-	char orig[200];
-	char pass[200];
-
-	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) {
-	syslog(LOG_WARNING, "incorrect password for '%s'",
-	pw->pw_name);
-	bb_do_delay(FAIL_DELAY);
-	puts("Incorrect password");
-	/* return -1; */
-	return 1;
-	}
-	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"
-	"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;
-	}
-	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) {
-	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);
-
-	memset(pass, 0, sizeof pass);
-	safe_strncpy(crypt_passwd, cp, sizeof(crypt_passwd));
+	if (ENABLE_FEATURE_CLEAN_UP) free(newp);
+	skip:
+	if (ENABLE_FEATURE_CLEAN_UP) free(myname);
	return 0;
	}
-
-	static void set_filesize_limit(int blocks)
-	{
-	struct rlimit rlimit_fsize;
-
-	rlimit_fsize.rlim_cur = rlimit_fsize.rlim_max = 512L * blocks;
-	setrlimit(RLIMIT_FSIZE, &rlimit_fsize);
-	}