| 1 | /* |
| 2 | ** Copyright 1998 - 1999 Double Precision, Inc. See COPYING for |
| 3 | ** distribution information. |
| 4 | */ |
| 5 | |
| 6 | #if HAVE_CONFIG_H |
| 7 | #include "courier_auth_config.h" |
| 8 | #endif |
| 9 | #include <stdio.h> |
| 10 | #include <stdlib.h> |
| 11 | #include <string.h> |
| 12 | #include <errno.h> |
| 13 | #include "courierauthsasl.h" |
| 14 | #include "cramlib.h" |
| 15 | #include "courierauthdebug.h" |
| 16 | |
| 17 | #if HAVE_HMACLIB |
| 18 | |
| 19 | #include "libhmac/hmac.h" |
| 20 | #include "cramlib.h" |
| 21 | |
| 22 | static int nybble(int c) |
| 23 | { |
| 24 | if (c >= '0' && c <= '9') return (c-'0'); |
| 25 | if (c >= 'a' && c <= 'f') return (c-'a'+10); |
| 26 | if (c >= 'A' && c <= 'F') return (c-'A'+10); |
| 27 | return (-1); |
| 28 | } |
| 29 | |
| 30 | static int do_auth_verify_cram(struct hmac_hashinfo *hash, |
| 31 | const char *challenge, const char *response, |
| 32 | const char *hashsecret) |
| 33 | { |
| 34 | unsigned char *context; |
| 35 | unsigned i; |
| 36 | |
| 37 | if (strlen(hashsecret) != hash->hh_L*4 || |
| 38 | strlen(response) != hash->hh_L*2) |
| 39 | return (-1); |
| 40 | |
| 41 | if ((context=malloc(hash->hh_L*3)) == 0) return (-1); |
| 42 | |
| 43 | for (i=0; i<hash->hh_L*2; i++) |
| 44 | { |
| 45 | int a=nybble(hashsecret[i*2]), b=nybble(hashsecret[i*2+1]); |
| 46 | |
| 47 | if (a < 0 || b < 0) |
| 48 | { |
| 49 | free(context); |
| 50 | return (-1); |
| 51 | } |
| 52 | context[i]= a*16 + b; |
| 53 | } |
| 54 | |
| 55 | hmac_hashtext(hash, challenge, strlen(challenge), |
| 56 | context, context+hash->hh_L, |
| 57 | context+hash->hh_L*2); |
| 58 | |
| 59 | for (i=0; i<hash->hh_L; i++) |
| 60 | { |
| 61 | int a=nybble(response[i*2]), b=nybble(response[i*2+1]); |
| 62 | |
| 63 | if ( (unsigned char)(a*16+b) != |
| 64 | context[hash->hh_L*2+i]) |
| 65 | { |
| 66 | free(context); |
| 67 | return (-1); |
| 68 | } |
| 69 | } |
| 70 | free(context); |
| 71 | return (0); |
| 72 | } |
| 73 | |
| 74 | int auth_verify_cram(struct hmac_hashinfo *hash, |
| 75 | const char *challenge, const char *response, |
| 76 | const char *hashsecret) |
| 77 | { |
| 78 | int rc; |
| 79 | |
| 80 | rc = do_auth_verify_cram(hash, challenge, response, hashsecret); |
| 81 | DPRINTF(rc ? "cram validation failed" : "cram validation succeeded"); |
| 82 | return rc; |
| 83 | } |
| 84 | |
| 85 | int auth_get_cram(const char *authtype, char *authdata, |
| 86 | struct cram_callback_info *craminfo) |
| 87 | { |
| 88 | int i; |
| 89 | int challenge_l; |
| 90 | int response_l; |
| 91 | |
| 92 | if (strncmp(authtype, "cram-", 5) || |
| 93 | (craminfo->challenge=strtok(authdata, "\n")) == 0 || |
| 94 | (craminfo->response=strtok(0, "\n")) == 0) |
| 95 | { |
| 96 | DPRINTF("cram: only supports authtype=cram-*"); |
| 97 | errno=EPERM; |
| 98 | return (-1); |
| 99 | } |
| 100 | |
| 101 | for (i=0; hmac_list[i]; i++) |
| 102 | if (strcmp(hmac_list[i]->hh_name, authtype+5) == 0) |
| 103 | break; |
| 104 | |
| 105 | DPRINTF("cram: challenge=%s, response=%s", craminfo->challenge, |
| 106 | craminfo->response); |
| 107 | |
| 108 | if (hmac_list[i] == 0 |
| 109 | || (challenge_l=authsasl_frombase64(craminfo->challenge)) < 0 |
| 110 | || (response_l=authsasl_frombase64(craminfo->response)) < 0) |
| 111 | { |
| 112 | DPRINTF("cram: invalid base64 encoding, or unknown method: %s", |
| 113 | authtype); |
| 114 | errno=EACCES; |
| 115 | return (-1); |
| 116 | } |
| 117 | craminfo->h=hmac_list[i]; |
| 118 | |
| 119 | for (i=response_l; i > 0; ) |
| 120 | { |
| 121 | if (craminfo->response[i-1] == ' ') |
| 122 | break; |
| 123 | --i; |
| 124 | } |
| 125 | |
| 126 | if (i == 0) |
| 127 | { |
| 128 | DPRINTF("cram: invalid base64 encoding"); |
| 129 | errno=EACCES; |
| 130 | return (-1); |
| 131 | } |
| 132 | craminfo->response[i-1]=0; |
| 133 | craminfo->user = craminfo->response; |
| 134 | craminfo->response += i; |
| 135 | response_l -= i; |
| 136 | |
| 137 | /* Since base64decoded data is always lesser in size (at least), |
| 138 | ** we can do the following: |
| 139 | */ |
| 140 | craminfo->challenge[challenge_l]=0; |
| 141 | craminfo->response[response_l]=0; |
| 142 | |
| 143 | /* we rely on DPRINTF doing a "safe" print here */ |
| 144 | DPRINTF("cram: decoded challenge/response, username '%s'", |
| 145 | craminfo->user); |
| 146 | return (0); |
| 147 | } |
| 148 | |
| 149 | int auth_cram_callback(struct authinfo *a, void *vp) |
| 150 | { |
| 151 | struct cram_callback_info *cci=(struct cram_callback_info *)vp; |
| 152 | unsigned char *hashbuf; |
| 153 | unsigned char *p; |
| 154 | unsigned i; |
| 155 | static const char hex[]="0123456789abcdef"; |
| 156 | int rc; |
| 157 | |
| 158 | if (!a->clearpasswd) |
| 159 | return (-1); |
| 160 | |
| 161 | /* |
| 162 | hmac->hh_L*2 will be the size of the binary hash. |
| 163 | |
| 164 | hmac->hh_L*4+1 will therefore be size of the binary hash, |
| 165 | as a hexadecimal string. |
| 166 | */ |
| 167 | |
| 168 | if ((hashbuf=malloc(cci->h->hh_L*6+1)) == 0) |
| 169 | return (1); |
| 170 | |
| 171 | hmac_hashkey(cci->h, a->clearpasswd, strlen(a->clearpasswd), |
| 172 | hashbuf, hashbuf+cci->h->hh_L); |
| 173 | |
| 174 | p=hashbuf+cci->h->hh_L*2; |
| 175 | |
| 176 | for (i=0; i<cci->h->hh_L*2; i++) |
| 177 | { |
| 178 | char c; |
| 179 | |
| 180 | c = hex[ (hashbuf[i] >> 4) & 0x0F]; |
| 181 | *p++=c; |
| 182 | |
| 183 | c = hex[ hashbuf[i] & 0x0F]; |
| 184 | *p++=c; |
| 185 | |
| 186 | *p=0; |
| 187 | } |
| 188 | |
| 189 | rc=auth_verify_cram(cci->h, cci->challenge, cci->response, |
| 190 | (const char *)hashbuf+cci->h->hh_L*2); |
| 191 | free(hashbuf); |
| 192 | |
| 193 | if (rc) return (rc); |
| 194 | |
| 195 | return (*cci->callback_func)(a, cci->callback_arg); |
| 196 | } |
| 197 | |
| 198 | |
| 199 | #endif |