adduser: safe username passing to passwd/addgroup

passwd: support creating SHA passwords
random code shrink

function                                             old     new   delta
crypt_make_pw_salt                                     -      87     +87
adduser_main                                         883     904     +21
...
crypt_make_salt                                       99      89     -10
chpasswd_main                                        329     312     -17
packed_usage                                       28731   28691     -40
passwd_main                                         1070    1000     -70
cryptpw_main                                         310     224     -86
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 4/12 up/down: 154/-288)        Total: -134 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 37 insertions, 38 deletions

diff --git a/loginutils/passwd.c b/loginutils/passwd.c
index 810644e61..8c47e65ff 100644
--- a/loginutils/passwd.c
+++ b/loginutils/passwd.c
@@ -9,7 +9,7 @@
 //usage:       "Change USER's password. If no USER is specified,\n"
 //usage:       "changes the password for the current user.\n"
 //usage:     "\nOptions:"
-//usage:     "\n	-a ALG	Algorithm to use for password (des, md5)" /* ", sha1)" */
+//usage:     "\n	-a ALG	Encryption method"
 //usage:     "\n	-d	Delete password for the account"
 //usage:     "\n	-l	Lock (disable) account"
 //usage:     "\n	-u	Unlock (re-enable) account"
@@ -22,15 +22,15 @@ static void nuke_str(char *str)
 	if (str) memset(str, 0, strlen(str));
 }
 
-static char* new_password(const struct passwd *pw, uid_t myuid, int algo)
+static char* new_password(const struct passwd *pw, uid_t myuid, const char *algo)
 {
-	char salt[sizeof("$N$XXXXXXXX")]; /* "$N$XXXXXXXX" or "XX" */
+	char salt[MAX_PW_SALT_LEN];
 	char *orig = (char*)"";
 	char *newp = NULL;
 	char *cp = NULL;
 	char *ret = NULL; /* failure so far */
 
-	if (myuid && pw->pw_passwd[0]) {
+	if (myuid != 0 && pw->pw_passwd[0]) {
 		char *encrypted;
 
 		orig = bb_ask_stdin("Old password: "); /* returns ptr to static */
@@ -38,13 +38,13 @@ static char* new_password(const struct passwd *pw, uid_t myuid, int algo)
 			goto err_ret;
 		encrypted = pw_encrypt(orig, pw->pw_passwd, 1); /* returns malloced str */
 		if (strcmp(encrypted, pw->pw_passwd) != 0) {
-			syslog(LOG_WARNING, "incorrect password for %s",
-				pw->pw_name);
+			syslog(LOG_WARNING, "incorrect password for %s", pw->pw_name);
 			bb_do_delay(LOGIN_FAIL_DELAY);
 			puts("Incorrect password");
 			goto err_ret;
 		}
-		if (ENABLE_FEATURE_CLEAN_UP) free(encrypted);
+		if (ENABLE_FEATURE_CLEAN_UP)
+			free(encrypted);
 	}
 	orig = xstrdup(orig); /* or else bb_ask_stdin() will destroy it */
 	newp = bb_ask_stdin("New password: "); /* returns ptr to static */
@@ -52,22 +52,22 @@ static char* new_password(const struct passwd *pw, uid_t myuid, int algo)
 		goto err_ret;
 	newp = xstrdup(newp); /* we are going to bb_ask_stdin() again, so save it */
 	if (ENABLE_FEATURE_PASSWD_WEAK_CHECK
-	 && obscure(orig, newp, pw) && myuid)
+	 && obscure(orig, newp, pw)
+	 && myuid != 0
+	) {
 		goto err_ret; /* non-root is not allowed to have weak passwd */
+	}
 
 	cp = bb_ask_stdin("Retype password: ");
 	if (!cp)
 		goto err_ret;
-	if (strcmp(cp, newp)) {
+	if (strcmp(cp, newp) != 0) {
 		puts("Passwords don't match");
 		goto err_ret;
 	}
 
-	crypt_make_salt(salt, 1, 0); /* des */
-	if (algo) { /* MD5 */
-		strcpy(salt, "$1$");
-		crypt_make_salt(salt + 3, 4, 0);
-	}
+	crypt_make_pw_salt(salt, algo);
+
 	/* pw_encrypt returns malloced str */
 	ret = pw_encrypt(newp, salt, 1);
 	/* whee, success! */
@@ -75,8 +75,10 @@ static char* new_password(const struct passwd *pw, uid_t myuid, int algo)
  err_ret:
 	nuke_str(orig);
 	if (ENABLE_FEATURE_CLEAN_UP) free(orig);
+
 	nuke_str(newp);
 	if (ENABLE_FEATURE_CLEAN_UP) free(newp);
+
 	nuke_str(cp);
 	return ret;
 }
@@ -85,17 +87,15 @@ int passwd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int passwd_main(int argc UNUSED_PARAM, 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, not needed yet
+		OPT_algo   = (1 << 0), /* -a - password algorithm */
+		OPT_lock   = (1 << 1), /* -l - lock account */
+		OPT_unlock = (1 << 2), /* -u - unlock account */
+		OPT_delete = (1 << 3), /* -d - delete password */
+		OPT_lud    = OPT_lock | OPT_unlock | OPT_delete,
 	};
 	unsigned opt;
 	int rc;
-	const char *opt_a = "";
+	const char *opt_a = "d"; /* des */
 	const char *filename;
 	char *myname;
 	char *name;
@@ -116,13 +116,9 @@ int passwd_main(int argc UNUSED_PARAM, char **argv)
 	//argc -= optind;
 	argv += optind;
 
-	if (strcasecmp(opt_a, "des") != 0) /* -a */
-		opt |= STATE_ALGO_md5;
-	//else
-	//	opt |= STATE_ALGO_des;
 	myuid = getuid();
 	/* -l, -u, -d require root priv and username argument */
-	if ((opt & OPT_lud) && (myuid || !argv[0]))
+	if ((opt & OPT_lud) && (myuid != 0 || !argv[0]))
 		bb_show_usage();
 
 	/* Will complain and die if username not found */
@@ -130,7 +126,7 @@ int passwd_main(int argc UNUSED_PARAM, char **argv)
 	name = argv[0] ? argv[0] : myname;
 
 	pw = xgetpwnam(name);
-	if (myuid && pw->pw_uid != myuid) {
+	if (myuid != 0 && pw->pw_uid != myuid) {
 		/* LOGMODE_BOTH */
 		bb_error_msg_and_die("%s can't change password for %s", myname, name);
 	}
@@ -164,27 +160,29 @@ int passwd_main(int argc UNUSED_PARAM, char **argv)
 	newp = NULL;
 	c = pw->pw_passwd[0] - '!';
 	if (!(opt & OPT_lud)) {
-		if (myuid && !c) { /* passwd starts with '!' */
+		if (myuid != 0 && !c) { /* passwd starts with '!' */
 			/* LOGMODE_BOTH */
 			bb_error_msg_and_die("can't change "
 					"locked password for %s", name);
 		}
 		printf("Changing password for %s\n", name);
-		newp = new_password(pw, myuid, opt & STATE_ALGO_md5);
+		newp = new_password(pw, myuid, opt_a);
 		if (!newp) {
 			logmode = LOGMODE_STDIO;
 			bb_error_msg_and_die("password for %s is unchanged", name);
 		}
 	} else if (opt & OPT_lock) {
-		if (!c) goto skip; /* passwd starts with '!' */
+		if (!c)
+			goto skip; /* passwd starts with '!' */
 		newp = xasprintf("!%s", pw->pw_passwd);
 	} else if (opt & OPT_unlock) {
-		if (c) goto skip; /* not '!' */
+		if (c)
+			goto skip; /* not '!' */
 		/* pw->pw_passwd points to static storage,
 		 * strdup'ing to avoid nasty surprizes */
 		newp = xstrdup(&pw->pw_passwd[1]);
 	} else if (opt & OPT_delete) {
-		newp = (char*)""; //xstrdup("");
+		newp = (char*)"";
 	}
 
 	rlimit_fsize.rlim_cur = rlimit_fsize.rlim_max = 512L * 30000;
@@ -202,7 +200,7 @@ int passwd_main(int argc UNUSED_PARAM, char **argv)
 	rc = update_passwd(bb_path_shadow_file, name, newp, NULL);
 	if (rc > 0)
 		/* password in /etc/shadow was updated */
-		newp = (char*) "x"; //xstrdup("x");
+		newp = (char*) "x";
 	if (rc >= 0)
 		/* 0 = /etc/shadow missing (not an error), >0 = passwd changed in /etc/shadow */
 #endif
@@ -212,16 +210,17 @@ int passwd_main(int argc UNUSED_PARAM, char **argv)
 	}
 	/* LOGMODE_BOTH */
 	if (rc < 0)
-		bb_error_msg_and_die("can't update password file %s",
-				filename);
+		bb_error_msg_and_die("can't update password file %s", filename);
 	bb_info_msg("Password for %s changed by %s", name, myname);
 
-	//if (ENABLE_FEATURE_CLEAN_UP) free(newp);
+	/*if (ENABLE_FEATURE_CLEAN_UP) free(newp); - can't, it may be non-malloced */
  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);
+
+	if (ENABLE_FEATURE_CLEAN_UP)
+		free(myname);
 	return 0;
 }