| [9] | 1 | /* pwdauth 2.0 - check a shadow password Author: Kees J. Bot
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| 2 | * 7 Feb 1994
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| 3 | *
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| 4 | * This program gets as input the key and salt arguments of the crypt(3)
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| 5 | * function as two null terminated strings. The crypt result is output as
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| 6 | * one null terminated string. Input and output must be <= 1024 characters.
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| 7 | * The exit code will be 1 on any error.
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| 8 | *
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| 9 | * If the key has the form '##name' then the key will be encrypted and the
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| 10 | * result checked to be equal to the encrypted password in the shadow password
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| 11 | * file. If equal than '##name' will be returned, otherwise exit code 2.
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| 12 | *
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| 13 | * Otherwise the key will be encrypted normally and the result returned.
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| 14 | *
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| 15 | * As a special case, anything matches a null encrypted password to allow
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| 16 | * a no-password login.
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| 17 | */
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| 18 | #define nil 0
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| 19 | #define crypt CRYPT /* The true crypt is included here. */
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| 20 | #include <sys/types.h>
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| 21 | #include <pwd.h>
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| 22 | #include <stdlib.h>
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| 23 | #include <stdio.h>
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| 24 | #include <string.h>
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| 25 | #include <unistd.h>
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| 26 |
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| 27 | #define LEN 1024
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| 28 | char SHADOW[] = "/etc/shadow";
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| 29 |
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| 30 | int main(int argc, char **argv)
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| 31 | {
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| 32 | char key[LEN];
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| 33 | char *salt;
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| 34 | struct passwd *pw;
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| 35 | int n;
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| 36 |
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| 37 | /* Read input data. Check if there are exactly two null terminated
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| 38 | * strings.
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| 39 | */
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| 40 | n= read(0, key, LEN);
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| 41 | if (n < 0) return 1;
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| 42 | salt = key + n;
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| 43 | n = 0;
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| 44 | while (salt > key) if (*--salt == 0) n++;
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| 45 | if (n != 2) return 1;
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| 46 | salt = key + strlen(key) + 1;
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| 47 |
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| 48 | if (salt[0] == '#' && salt[1] == '#') {
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| 49 | /* Get the encrypted password from the shadow password file,
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| 50 | * encrypt key and compare.
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| 51 | */
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| 52 | setpwfile(SHADOW);
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| 53 |
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| 54 | if ((pw= getpwnam(salt + 2)) == nil) return 2;
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| 55 |
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| 56 | /* A null encrypted password matches a null key, otherwise
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| 57 | * do the normal crypt(3) authentication check.
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| 58 | */
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| 59 | if (*pw->pw_passwd == 0 && *key == 0) {
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| 60 | /* fine */
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| 61 | } else
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| 62 | if (strcmp(crypt(key, pw->pw_passwd), pw->pw_passwd) != 0) {
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| 63 | return 2;
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| 64 | }
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| 65 | } else {
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| 66 | /* Normal encryption. */
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| 67 | if (*salt == 0 && *key == 0) {
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| 68 | /* fine */
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| 69 | } else {
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| 70 | salt= crypt(key, salt);
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| 71 | }
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| 72 | }
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| 73 |
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| 74 | /* Return the (possibly new) salt to the caller. */
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| 75 | if (write(1, salt, strlen(salt) + 1) < 0) return 1;
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| 76 | return 0;
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| 77 | }
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| 78 |
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| 79 | /* The one and only crypt(3) function. */
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| 80 |
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| 81 | /* From Andy Tanenbaum's book "Computer Networks",
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| 82 | rewritten in C
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| 83 | */
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| 84 |
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| 85 | struct block {
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| 86 | unsigned char b_data[64];
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| 87 | };
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| 88 |
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| 89 | struct ordering {
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| 90 | unsigned char o_data[64];
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| 91 | };
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| 92 |
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| 93 | static struct block key;
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| 94 |
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| 95 | static struct ordering InitialTr = {
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| 96 | 58,50,42,34,26,18,10, 2,60,52,44,36,28,20,12, 4,
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| 97 | 62,54,46,38,30,22,14, 6,64,56,48,40,32,24,16, 8,
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| 98 | 57,49,41,33,25,17, 9, 1,59,51,43,35,27,19,11, 3,
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| 99 | 61,53,45,37,29,21,13, 5,63,55,47,39,31,23,15, 7,
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| 100 | };
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| 101 |
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| 102 | static struct ordering FinalTr = {
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| 103 | 40, 8,48,16,56,24,64,32,39, 7,47,15,55,23,63,31,
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| 104 | 38, 6,46,14,54,22,62,30,37, 5,45,13,53,21,61,29,
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| 105 | 36, 4,44,12,52,20,60,28,35, 3,43,11,51,19,59,27,
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| 106 | 34, 2,42,10,50,18,58,26,33, 1,41, 9,49,17,57,25,
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| 107 | };
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| 108 |
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| 109 | static struct ordering swap = {
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| 110 | 33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,
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| 111 | 49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,
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| 112 | 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14,15,16,
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| 113 | 17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,
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| 114 | };
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| 115 |
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| 116 | static struct ordering KeyTr1 = {
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| 117 | 57,49,41,33,25,17, 9, 1,58,50,42,34,26,18,
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| 118 | 10, 2,59,51,43,35,27,19,11, 3,60,52,44,36,
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| 119 | 63,55,47,39,31,23,15, 7,62,54,46,38,30,22,
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| 120 | 14, 6,61,53,45,37,29,21,13, 5,28,20,12, 4,
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| 121 | };
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| 122 |
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| 123 | static struct ordering KeyTr2 = {
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| 124 | 14,17,11,24, 1, 5, 3,28,15, 6,21,10,
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| 125 | 23,19,12, 4,26, 8,16, 7,27,20,13, 2,
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| 126 | 41,52,31,37,47,55,30,40,51,45,33,48,
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| 127 | 44,49,39,56,34,53,46,42,50,36,29,32,
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| 128 | };
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| 129 |
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| 130 | static struct ordering etr = {
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| 131 | 32, 1, 2, 3, 4, 5, 4, 5, 6, 7, 8, 9,
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| 132 | 8, 9,10,11,12,13,12,13,14,15,16,17,
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| 133 | 16,17,18,19,20,21,20,21,22,23,24,25,
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| 134 | 24,25,26,27,28,29,28,29,30,31,32, 1,
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| 135 | };
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| 136 |
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| 137 | static struct ordering ptr = {
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| 138 | 16, 7,20,21,29,12,28,17, 1,15,23,26, 5,18,31,10,
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| 139 | 2, 8,24,14,32,27, 3, 9,19,13,30, 6,22,11, 4,25,
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| 140 | };
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| 141 |
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| 142 | static unsigned char s_boxes[8][64] = {
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| 143 | { 14, 4,13, 1, 2,15,11, 8, 3,10, 6,12, 5, 9, 0, 7,
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| 144 | 0,15, 7, 4,14, 2,13, 1,10, 6,12,11, 9, 5, 3, 8,
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| 145 | 4, 1,14, 8,13, 6, 2,11,15,12, 9, 7, 3,10, 5, 0,
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| 146 | 15,12, 8, 2, 4, 9, 1, 7, 5,11, 3,14,10, 0, 6,13,
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| 147 | },
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| 148 |
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| 149 | { 15, 1, 8,14, 6,11, 3, 4, 9, 7, 2,13,12, 0, 5,10,
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| 150 | 3,13, 4, 7,15, 2, 8,14,12, 0, 1,10, 6, 9,11, 5,
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| 151 | 0,14, 7,11,10, 4,13, 1, 5, 8,12, 6, 9, 3, 2,15,
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| 152 | 13, 8,10, 1, 3,15, 4, 2,11, 6, 7,12, 0, 5,14, 9,
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| 153 | },
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| 154 |
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| 155 | { 10, 0, 9,14, 6, 3,15, 5, 1,13,12, 7,11, 4, 2, 8,
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| 156 | 13, 7, 0, 9, 3, 4, 6,10, 2, 8, 5,14,12,11,15, 1,
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| 157 | 13, 6, 4, 9, 8,15, 3, 0,11, 1, 2,12, 5,10,14, 7,
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| 158 | 1,10,13, 0, 6, 9, 8, 7, 4,15,14, 3,11, 5, 2,12,
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| 159 | },
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| 160 |
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| 161 | { 7,13,14, 3, 0, 6, 9,10, 1, 2, 8, 5,11,12, 4,15,
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| 162 | 13, 8,11, 5, 6,15, 0, 3, 4, 7, 2,12, 1,10,14, 9,
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| 163 | 10, 6, 9, 0,12,11, 7,13,15, 1, 3,14, 5, 2, 8, 4,
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| 164 | 3,15, 0, 6,10, 1,13, 8, 9, 4, 5,11,12, 7, 2,14,
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| 165 | },
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| 166 |
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| 167 | { 2,12, 4, 1, 7,10,11, 6, 8, 5, 3,15,13, 0,14, 9,
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| 168 | 14,11, 2,12, 4, 7,13, 1, 5, 0,15,10, 3, 9, 8, 6,
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| 169 | 4, 2, 1,11,10,13, 7, 8,15, 9,12, 5, 6, 3, 0,14,
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| 170 | 11, 8,12, 7, 1,14, 2,13, 6,15, 0, 9,10, 4, 5, 3,
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| 171 | },
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| 172 |
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| 173 | { 12, 1,10,15, 9, 2, 6, 8, 0,13, 3, 4,14, 7, 5,11,
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| 174 | 10,15, 4, 2, 7,12, 9, 5, 6, 1,13,14, 0,11, 3, 8,
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| 175 | 9,14,15, 5, 2, 8,12, 3, 7, 0, 4,10, 1,13,11, 6,
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| 176 | 4, 3, 2,12, 9, 5,15,10,11,14, 1, 7, 6, 0, 8,13,
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| 177 | },
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| 178 |
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| 179 | { 4,11, 2,14,15, 0, 8,13, 3,12, 9, 7, 5,10, 6, 1,
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| 180 | 13, 0,11, 7, 4, 9, 1,10,14, 3, 5,12, 2,15, 8, 6,
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| 181 | 1, 4,11,13,12, 3, 7,14,10,15, 6, 8, 0, 5, 9, 2,
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| 182 | 6,11,13, 8, 1, 4,10, 7, 9, 5, 0,15,14, 2, 3,12,
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| 183 | },
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| 184 |
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| 185 | { 13, 2, 8, 4, 6,15,11, 1,10, 9, 3,14, 5, 0,12, 7,
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| 186 | 1,15,13, 8,10, 3, 7, 4,12, 5, 6,11, 0,14, 9, 2,
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| 187 | 7,11, 4, 1, 9,12,14, 2, 0, 6,10,13,15, 3, 5, 8,
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| 188 | 2, 1,14, 7, 4,10, 8,13,15,12, 9, 0, 3, 5, 6,11,
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| 189 | },
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| 190 | };
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| 191 |
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| 192 | static int rots[] = {
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| 193 | 1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1,
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| 194 | };
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| 195 |
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| 196 | static void transpose(struct block *data, struct ordering *t, int n)
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| 197 | {
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| 198 | struct block x;
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| 199 |
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| 200 | x = *data;
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| 201 |
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| 202 | while (n-- > 0) {
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| 203 | data->b_data[n] = x.b_data[t->o_data[n] - 1];
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| 204 | }
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| 205 | }
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| 206 |
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| 207 | static void rotate(struct block *key)
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| 208 | {
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| 209 | unsigned char *p = key->b_data;
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| 210 | unsigned char *ep = &(key->b_data[55]);
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| 211 | int data0 = key->b_data[0], data28 = key->b_data[28];
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| 212 |
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| 213 | while (p++ < ep) *(p-1) = *p;
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| 214 | key->b_data[27] = data0;
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| 215 | key->b_data[55] = data28;
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| 216 | }
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| 217 |
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| 218 | static struct ordering *EP = &etr;
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| 219 |
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| 220 | static void f(int i, struct block *key, struct block *a, struct block *x)
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| 221 | {
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| 222 | struct block e, ikey, y;
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| 223 | int k;
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| 224 | unsigned char *p, *q, *r;
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| 225 |
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| 226 | e = *a;
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| 227 | transpose(&e, EP, 48);
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| 228 | for (k = rots[i]; k; k--) rotate(key);
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| 229 | ikey = *key;
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| 230 | transpose(&ikey, &KeyTr2, 48);
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| 231 | p = &(y.b_data[48]);
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| 232 | q = &(e.b_data[48]);
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| 233 | r = &(ikey.b_data[48]);
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| 234 | while (p > y.b_data) {
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| 235 | *--p = *--q ^ *--r;
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| 236 | }
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| 237 | q = x->b_data;
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| 238 | for (k = 0; k < 8; k++) {
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| 239 | int xb, r;
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| 240 |
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| 241 | r = *p++ << 5;
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| 242 | r += *p++ << 3;
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| 243 | r += *p++ << 2;
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| 244 | r += *p++ << 1;
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| 245 | r += *p++;
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| 246 | r += *p++ << 4;
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| 247 |
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| 248 | xb = s_boxes[k][r];
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| 249 |
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| 250 | *q++ = (xb >> 3) & 1;
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| 251 | *q++ = (xb>>2) & 1;
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| 252 | *q++ = (xb>>1) & 1;
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| 253 | *q++ = (xb & 1);
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| 254 | }
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| 255 | transpose(x, &ptr, 32);
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| 256 | }
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| 257 |
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| 258 | static void setkey(char *k)
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| 259 | {
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| 260 |
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| 261 | key = *((struct block *) k);
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| 262 | transpose(&key, &KeyTr1, 56);
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| 263 | }
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| 264 |
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| 265 | static void encrypt(char *blck, int edflag)
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| 266 | {
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| 267 | struct block *p = (struct block *) blck;
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| 268 | int i;
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| 269 |
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| 270 | transpose(p, &InitialTr, 64);
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| 271 | for (i = 15; i>= 0; i--) {
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| 272 | int j = edflag ? i : 15 - i;
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| 273 | int k;
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| 274 | struct block b, x;
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| 275 |
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| 276 | b = *p;
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| 277 | for (k = 31; k >= 0; k--) {
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| 278 | p->b_data[k] = b.b_data[k + 32];
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| 279 | }
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| 280 | f(j, &key, p, &x);
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| 281 | for (k = 31; k >= 0; k--) {
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| 282 | p->b_data[k+32] = b.b_data[k] ^ x.b_data[k];
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| 283 | }
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| 284 | }
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| 285 | transpose(p, &swap, 64);
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| 286 | transpose(p, &FinalTr, 64);
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| 287 | }
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| 288 |
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| 289 | char *crypt(const char *pw, const char *salt)
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| 290 | {
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| 291 | char pwb[66];
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| 292 | char *cp;
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| 293 | static char result[16];
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| 294 | char *p = pwb;
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| 295 | struct ordering new_etr;
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| 296 | int i;
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| 297 |
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| 298 | while (*pw && p < &pwb[64]) {
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| 299 | int j = 7;
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| 300 |
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| 301 | while (j--) {
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| 302 | *p++ = (*pw >> j) & 01;
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| 303 | }
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| 304 | pw++;
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| 305 | *p++ = 0;
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| 306 | }
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| 307 | while (p < &pwb[64]) *p++ = 0;
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| 308 |
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| 309 | setkey(p = pwb);
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| 310 |
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| 311 | while (p < &pwb[66]) *p++ = 0;
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| 312 |
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| 313 | new_etr = etr;
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| 314 | EP = &new_etr;
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| 315 | if (salt[0] == 0 || salt[1] == 0) salt = "**";
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| 316 | for (i = 0; i < 2; i++) {
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| 317 | char c = *salt++;
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| 318 | int j;
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| 319 |
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| 320 | result[i] = c;
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| 321 | if ( c > 'Z') c -= 6 + 7 + '.'; /* c was a lower case letter */
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| 322 | else if ( c > '9') c -= 7 + '.';/* c was upper case letter */
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| 323 | else c -= '.'; /* c was digit, '.' or '/'. */
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| 324 | /* now, 0 <= c <= 63 */
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| 325 | for (j = 0; j < 6; j++) {
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| 326 | if ((c >> j) & 01) {
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| 327 | int t = 6*i + j;
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| 328 | int temp = new_etr.o_data[t];
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| 329 | new_etr.o_data[t] = new_etr.o_data[t+24];
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| 330 | new_etr.o_data[t+24] = temp;
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| 331 | }
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| 332 | }
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| 333 | }
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| 334 |
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| 335 | if (result[1] == 0) result[1] = result[0];
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| 336 |
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| 337 | for (i = 0; i < 25; i++) encrypt(pwb,0);
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| 338 | EP = &etr;
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| 339 |
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| 340 | p = pwb;
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| 341 | cp = result+2;
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| 342 | while (p < &pwb[66]) {
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| 343 | int c = 0;
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| 344 | int j = 6;
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| 345 |
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| 346 | while (j--) {
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| 347 | c <<= 1;
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| 348 | c |= *p++;
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| 349 | }
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| 350 | c += '.'; /* becomes >= '.' */
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| 351 | if (c > '9') c += 7; /* not in [./0-9], becomes upper */
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| 352 | if (c > 'Z') c += 6; /* not in [A-Z], becomes lower */
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| 353 | *cp++ = c;
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| 354 | }
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| 355 | *cp = 0;
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| 356 | return result;
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| 357 | }
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