From 2c917f5acc008e73b367ecf82402b5eac08db10c Mon Sep 17 00:00:00 2001
From: Rob Landley <rob@landley.net>
Date: Tue, 17 Jul 2012 08:54:47 -0500
Subject: Add passwd by Kyungwan Han.

---
 toys/passwd.c | 274 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 274 insertions(+)
 create mode 100644 toys/passwd.c

(limited to 'toys')

diff --git a/toys/passwd.c b/toys/passwd.c
new file mode 100644
index 00000000..501ce952
--- /dev/null
+++ b/toys/passwd.c
@@ -0,0 +1,274 @@
+/* vi: set sw=4 ts=4:
+ *
+ * passwd.c - Program to upadte user password.
+ *
+ * Copyright 2012 Ashwini Kumar <ak.ashwini@gmail.com>
+ * Modified 2012 Jason Kyungwan Han <asura321@gmail.com>
+ *
+ * Not in SUSv4.
+
+USE_PASSWD(NEWTOY(passwd, ">1a:dlu", TOYFLAG_STAYROOT|TOYFLAG_USR|TOYFLAG_BIN))
+
+config PASSWD
+	bool "passwd"
+	default y
+	help
+	  usage: passwd [-a ALGO] [-d] [-l] [-u] <account name>
+
+	  update user’s authentication tokens. Default : current user
+
+	  -a ALGO	Encryption method (des, md5, sha256, sha512) default: des
+	  -d		Set password to ''
+	  -l		Lock (disable) account
+	  -u 		Unlock (enable) account
+
+*/
+
+#include "toys.h"
+#include <time.h>
+
+
+DEFINE_GLOBALS(
+	char *algo;
+)
+
+#define TT this.passwd
+
+#define FLAG_u	(1 << 0)
+#define FLAG_l	(1 << 1)
+#define FLAG_d	(1 << 2)
+#define FLAG_a	(1 << 3)
+
+#define MAX_SALT_LEN  20 //3 for id, 16 for key, 1 for '\0'
+#define URANDOM_PATH    "/dev/urandom"
+
+#ifndef _GNU_SOURCE
+char *strcasestr(const char *haystack, const char *needle);
+#endif
+
+unsigned int random_number_generator(int fd)
+{
+    unsigned int randnum;
+    xreadall(fd, &randnum, sizeof(randnum));
+	return randnum;
+}
+
+
+
+char inttoc(int i)
+{
+	// salt value uses 64 chracters in "./0-9a-zA-Z"
+	const char character_set[]="./0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
+    i &= 0x3f; // masking for using 10 bits only
+	return character_set[i];
+}
+
+int get_salt(char *salt)
+{                     
+	int i, salt_length = 0;
+    int randfd;
+	if(!strncmp(TT.algo,"des",3)){
+		// 2 bytes salt value is used in des
+		salt_length = 2;
+	} else {
+		*salt++ = '$';
+		if(!strncmp(TT.algo,"md5",3)){
+			*salt++ = '1';
+			// 8 bytes salt value is used in md5
+			salt_length = 8;
+		} else if(!strncmp(TT.algo,"sha256",6)){
+			*salt++ = '5';
+			// 16 bytes salt value is used in sha256
+			salt_length = 16;
+		} else if(!strncmp(TT.algo,"sha512",6)){
+			*salt++ = '6';
+			// 16 bytes salt value is used in sha512
+			salt_length = 16;
+		} else return 1;
+
+		*salt++ = '$';
+	}
+
+    randfd = xopen(URANDOM_PATH, O_RDONLY);
+	for(i=0; i<salt_length; i++)
+		salt[i] = inttoc(random_number_generator(randfd));
+	salt[salt_length+1] = '\0';
+    xclose(randfd);
+
+	return 0;
+}
+
+static int str_check(char *s, char *p)
+{
+    if((strcasestr(s, p) != NULL) || (strcasestr(p, s) != NULL))
+        return 1;
+    return 0;
+}
+
+static void strength_check(char *newp, char *oldp, char *user)
+{
+    char *msg = NULL;
+    if(strlen(newp) < 6) { //Min passwd len
+        msg = "too short";
+        xprintf("BAD PASSWORD: %s\n",msg);
+    }
+    if(!newp[0])
+        return; //passwd is empty
+
+    if(str_check(newp, user)) {
+        msg = "user based password";
+        xprintf("BAD PASSWORD: %s\n",msg);
+    }
+
+    if(oldp[0] && str_check(newp, oldp)) {
+        msg = "based on old passwd";
+        xprintf("BAD PASSWORD: %s\n",msg);
+    }
+}
+
+static int verify_passwd(char * pwd)
+{    
+    char * pass;
+
+    if (!pwd) return 1;
+    if (pwd[0] == '!' || pwd[0] == '*') return 1;
+
+    pass = crypt(toybuf, pwd);
+    if (pass != NULL && strcmp(pass, pwd)==0)
+        return 0;
+
+    return 1;
+}
+
+static char *new_password(char *oldp, char *user)
+{
+    char *newp = NULL;
+
+    if(read_passwd(toybuf, sizeof(toybuf), "New password:"))
+        return NULL; //may be due to Ctrl-C
+
+    newp = xstrdup(toybuf);
+    strength_check(newp, oldp, user);
+    if(read_passwd(toybuf, sizeof(toybuf), "Retype password:")) {
+        free(newp);
+        return NULL; //may be due to Ctrl-C
+    }
+
+    if(strcmp(newp, toybuf) == 0)
+        return newp;
+    else error_msg("Passwords do not match.\n");
+    /*Failure Case */
+    free(newp);
+    return NULL;
+}
+
+
+void passwd_main(void)
+{
+    uid_t myuid;
+    struct passwd *pw;
+    struct spwd *sp;
+    char *name = NULL;
+    char *pass = NULL, *encrypted = NULL, *newp = NULL;
+    char *orig = (char *)"";
+    char salt[MAX_SALT_LEN];
+    int ret = -1;
+
+    myuid = getuid();
+    if((myuid != 0) && (toys.optflags & (FLAG_l | FLAG_u | FLAG_d)))
+        error_exit("You need to be root to do these actions\n");
+
+    pw = getpwuid(myuid);
+
+    if(!pw)
+        error_exit("Unknown uid '%u'",myuid);
+
+    if(toys.optargs[0])
+        name = toys.optargs[0];
+    else
+        name = xstrdup(pw->pw_name);
+
+    pw = getpwnam(name);
+    if(!pw) error_exit("Unknown user '%s'",name);
+
+    if(myuid != 0 && (myuid != pw->pw_uid))
+        error_exit("You need to be root to change '%s' password\n", name);
+
+    pass = pw->pw_passwd;
+    if(pw->pw_passwd[0] == 'x') {
+        /*get shadow passwd */
+        sp = getspnam(name);
+        if(sp)
+            pass = sp->sp_pwdp;
+    }
+
+
+    if(!(toys.optflags & (FLAG_l | FLAG_u | FLAG_d))) {
+        printf("Changing password for %s\n",name);
+        if(pass[0] == '!') 
+            error_exit("Can't change, password is locked for %s",name);
+        if(myuid != 0) {
+            /*Validate user */
+
+            if(read_passwd(toybuf, sizeof(toybuf), "Origial password:")) {
+                if(!toys.optargs[0]) free(name);
+                return;
+            }
+            orig = toybuf;
+            if(verify_passwd(pass))
+                error_exit("Authentication failed\n");
+        }
+
+        orig = xstrdup(orig);
+
+        /*Get new password */
+        newp = new_password(orig, name);
+        if(!newp) {
+            free(orig);
+            if(!toys.optargs[0]) free(name);
+            return; //new password is not set well.
+        }
+
+        /*Encrypt the passwd */
+        if(!(toys.optflags & FLAG_a)) TT.algo = "des";
+
+		if(get_salt(salt))
+			error_exit("Error: Unkown encryption algorithm\n");
+		
+        encrypted = crypt(newp, salt);
+        free(newp);
+        free(orig);
+    }
+    else if(toys.optflags & FLAG_l) {
+        if(pass[0] == '!')
+            error_exit("password is already locked for %s",name);
+        printf("Locking password for %s\n",name);
+        encrypted = xmsprintf("!%s",pass);
+    }
+    else if(toys.optflags & FLAG_u) {
+        if(pass[0] != '!')         
+            error_exit("password is already unlocked for %s",name);
+
+        printf("Unlocking password for %s\n",name);
+        encrypted = xstrdup(&pass[1]);
+    }
+    else if(toys.optflags & FLAG_d) {
+        printf("Deleting password for %s\n",name);
+        encrypted = (char*)xzalloc(sizeof(char)*2); //1 = "", 2 = '\0'
+    }
+
+    /*Update the passwd */
+    if(pw->pw_passwd[0] == 'x')
+        ret = update_passwd("/etc/shadow", name, encrypted);
+    else
+        ret = update_passwd("/etc/passwd", name, encrypted);
+
+    if((toys.optflags & (FLAG_l | FLAG_u | FLAG_d))) 
+        free(encrypted);
+
+    if(!toys.optargs[0]) free(name);
+    if(!ret)
+        error_msg("Success");
+    else
+        error_msg("Failure");
+}
-- 
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