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radius: fix the MPPE key decryption for the second-half of the key #463

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merged 1 commit into from
Dec 21, 2023
Merged

radius: fix the MPPE key decryption for the second-half of the key #463

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115 changes: 55 additions & 60 deletions pppd/plugins/radius/radius.c
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Original file line number Diff line number Diff line change
Expand Up @@ -897,80 +897,75 @@ radius_setmppekeys2(VALUE_PAIR *vp, REQUEST_INFO *req_info)
memcpy(plain, crypt, 32);

ctx = PPP_MD_CTX_new();
if (ctx) {

if (PPP_DigestInit(ctx, PPP_md5())) {

if (PPP_DigestUpdate(ctx, req_info->secret, strlen(req_info->secret))) {

if (PPP_DigestUpdate(ctx, req_info->request_vector, AUTH_VECTOR_LEN)) {

if (PPP_DigestUpdate(ctx, salt, 2)) {

buflen = sizeof(buf);
if (PPP_DigestFinal(ctx, buf, &buflen)) {

status = 1;
}
}
}
}
}

PPP_MD_CTX_free(ctx);
if (!ctx) {
error("RADIUS: Error creating PPP_MD_CTX for MS-MPPE-%s-Key attribute", type);
return -1;
}

if (status) {

for (i = 0; i < 16; i++) {
plain[i] ^= buf[i];
}
buflen = sizeof(buf);
if (!PPP_DigestInit(ctx, PPP_md5())) {
error("RADIUS: Error setting hash algorithm to MD5 for MS-MPPE-%s-Key attribute", type);
} else if (!PPP_DigestUpdate(ctx, req_info->secret, strlen(req_info->secret))) {
error("RADIUS: Error mixing in radius secret for MS-MPPE-%s-Key attribute", type);
} else if (!PPP_DigestUpdate(ctx, req_info->request_vector, AUTH_VECTOR_LEN)) {
error("RADIUS: Error mixing in request vector for MS-MPPE-%s-Key attribute", type);
} else if (!PPP_DigestUpdate(ctx, salt, 2)) {
error("RADIUS: Error mixing in salt for MS-MPPE-%s-Key attribute", type);
} else if (!PPP_DigestFinal(ctx, buf, &buflen)) {
error("RADIUS: Error finalizing key buffer for MS-MPPE-%s-Key attribute", type);
} else {
status = 1;
}

if (plain[0] != 16) {
error("RADIUS: Incorrect key length (%d) for MS-MPPE-%s-Key attribute",
(int) plain[0], type);
return -1;
}
PPP_MD_CTX_free(ctx);

status = 0;
ctx = PPP_MD_CTX_new();
if (ctx) {

if (PPP_DigestInit(ctx, PPP_md5())) {
if (!status)
return -1;

if (PPP_DigestUpdate(ctx, req_info->secret, strlen(req_info->secret))) {
for (i = 0; i < 16; i++) {
plain[i] ^= buf[i];
}

if (PPP_DigestUpdate(ctx, crypt, 16)) {
if (plain[0] != 16) {
error("RADIUS: Incorrect key length (%d) for MS-MPPE-%s-Key attribute",
(int) plain[0], type);
return -1;
}

if (PPP_DigestUpdate(ctx, salt, 2)) {
status = 0;
ctx = PPP_MD_CTX_new();
if (!ctx) {
error("RADIUS: Error creating PPP_MD_CTX for MS-MPPE-%s-Key(2) attribute", type);
return -1;
}

buflen = sizeof(buf);
if (PPP_DigestFinal(ctx, buf, &buflen)) {
buflen = sizeof(buf);

status = 1;
}
}
}
}
}
if (!PPP_DigestInit(ctx, PPP_md5())) {
error("RADIUS: Error setting hash algorithm to MD5 for MS-MPPE-%s-Key(2) attribute", type);
} else if (!PPP_DigestUpdate(ctx, req_info->secret, strlen(req_info->secret))) {
error("RADIUS: Error mixing in radius secret for MS-MPPE-%s-Key(2) attribute", type);
} else if (!PPP_DigestUpdate(ctx, crypt, 16)) {
error("RADIUS: Error mixing in crypt vector for MS-MPPE-%s-Key(2) attribute", type);
} else if (!PPP_DigestFinal(ctx, buf, &buflen)) {
error("RADIUS: Error finalizing key buffer for MS-MPPE-%s-Key(2) attribute", type);
} else {
status = 1;
}

PPP_MD_CTX_free(ctx);
}
PPP_MD_CTX_free(ctx);

if (status) {
if (!status)
return -1;

plain[16] ^= buf[0]; /* only need the first byte */
plain[16] ^= buf[0]; /* only need the first byte */

if (vp->attribute == PW_MS_MPPE_SEND_KEY) {
mppe_set_keys(plain + 1, NULL, 16);
} else {
mppe_set_keys(NULL, plain + 1, 16);
}
return 0;
}
if (vp->attribute == PW_MS_MPPE_SEND_KEY) {
mppe_set_keys(plain + 1, NULL, 16);
} else {
mppe_set_keys(NULL, plain + 1, 16);
}

return -1;
return 0;
}
#endif /* PPP_WITH_MPPE */

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