krb5/krb5-1.17-In-FIPS-mode-add-plaintext-fallback-for-RC.patch

From 105bd2c8be23ab94ba6e0601ee8e531f013389d6 Mon Sep 17 00:00:00 2001
From: Robbie Harwood <rharwood@redhat.com>
Date: Tue, 31 Jul 2018 13:47:26 -0400
Subject: [PATCH] krb5-1.17 In FIPS mode, add plaintext fallback for RC4 usages
 and taint

---
 src/lib/krad/attr.c      | 45 +++++++++++++++++++++++++++++-----------
 src/lib/krad/attrset.c   |  5 +++--
 src/lib/krad/internal.h  | 13 ++++++++++--
 src/lib/krad/packet.c    | 22 +++++++++++---------
 src/lib/krad/remote.c    | 10 +++++++--
 src/lib/krad/t_attr.c    |  3 ++-
 src/lib/krad/t_attrset.c |  4 +++-
 7 files changed, 72 insertions(+), 30 deletions(-)

diff --git a/src/lib/krad/attr.c b/src/lib/krad/attr.c
index 9c13d9d75..275327e67 100644
--- a/src/lib/krad/attr.c
+++ b/src/lib/krad/attr.c
@@ -30,6 +30,7 @@
 #include <k5-int.h>
 #include "internal.h"
 
+#include <openssl/crypto.h>
 #include <string.h>
 
 /* RFC 2865 */
@@ -38,7 +39,8 @@
 typedef krb5_error_code
 (*attribute_transform_fn)(krb5_context ctx, const char *secret,
                           const unsigned char *auth, const krb5_data *in,
-                          unsigned char outbuf[MAX_ATTRSIZE], size_t *outlen);
+                          unsigned char outbuf[MAX_ATTRSIZE], size_t *outlen,
+                          krb5_boolean *is_fips);
 
 typedef struct {
     const char *name;
@@ -51,12 +53,14 @@ typedef struct {
 static krb5_error_code
 user_password_encode(krb5_context ctx, const char *secret,
                      const unsigned char *auth, const krb5_data *in,
-                     unsigned char outbuf[MAX_ATTRSIZE], size_t *outlen);
+                     unsigned char outbuf[MAX_ATTRSIZE], size_t *outlen,
+                     krb5_boolean *is_fips);
 
 static krb5_error_code
 user_password_decode(krb5_context ctx, const char *secret,
                      const unsigned char *auth, const krb5_data *in,
-                     unsigned char outbuf[MAX_ATTRSIZE], size_t *outlen);
+                     unsigned char outbuf[MAX_ATTRSIZE], size_t *outlen,
+                     krb5_boolean *ignored);
 
 static const attribute_record attributes[UCHAR_MAX] = {
     {"User-Name", 1, MAX_ATTRSIZE, NULL, NULL},
@@ -128,7 +132,8 @@ static const attribute_record attributes[UCHAR_MAX] = {
 static krb5_error_code
 user_password_encode(krb5_context ctx, const char *secret,
                      const unsigned char *auth, const krb5_data *in,
-                     unsigned char outbuf[MAX_ATTRSIZE], size_t *outlen)
+                     unsigned char outbuf[MAX_ATTRSIZE], size_t *outlen,
+                     krb5_boolean *is_fips)
 {
     const unsigned char *indx;
     krb5_error_code retval;
@@ -154,8 +159,14 @@ user_password_encode(krb5_context ctx, const char *secret,
     for (blck = 0, indx = auth; blck * BLOCKSIZE < len; blck++) {
         memcpy(tmp.data + seclen, indx, BLOCKSIZE);
 
-        retval = krb5_c_make_checksum(ctx, CKSUMTYPE_RSA_MD5, NULL, 0, &tmp,
-                                      &sum);
+        if (FIPS_mode()) {
+            /* Skip encryption here.  Taint so that we won't pass it out of
+             * the machine by accident. */
+            *is_fips = TRUE;
+            sum.contents = calloc(1, BLOCKSIZE);
+        } else
+            retval = krb5_c_make_checksum(ctx, CKSUMTYPE_RSA_MD5, NULL, 0, &tmp,
+                                          &sum);
         if (retval != 0) {
             zap(tmp.data, tmp.length);
             zap(outbuf, len);
@@ -180,7 +191,8 @@ user_password_encode(krb5_context ctx, const char *secret,
 static krb5_error_code
 user_password_decode(krb5_context ctx, const char *secret,
                      const unsigned char *auth, const krb5_data *in,
-                     unsigned char outbuf[MAX_ATTRSIZE], size_t *outlen)
+                     unsigned char outbuf[MAX_ATTRSIZE], size_t *outlen,
+                     krb5_boolean *is_fips)
 {
     const unsigned char *indx;
     krb5_error_code retval;
@@ -204,8 +216,14 @@ user_password_decode(krb5_context ctx, const char *secret,
     for (blck = 0, indx = auth; blck * BLOCKSIZE < in->length; blck++) {
         memcpy(tmp.data + seclen, indx, BLOCKSIZE);
 
-        retval = krb5_c_make_checksum(ctx, CKSUMTYPE_RSA_MD5, NULL, 0,
-                                      &tmp, &sum);
+        if (FIPS_mode()) {
+            /* Skip encryption here.  Taint so that we won't pass it out of
+             * the machine by accident. */
+            *is_fips = TRUE;
+            sum.contents = calloc(1, BLOCKSIZE);
+        } else
+            retval = krb5_c_make_checksum(ctx, CKSUMTYPE_RSA_MD5, NULL, 0,
+                                          &tmp, &sum);
         if (retval != 0) {
             zap(tmp.data, tmp.length);
             zap(outbuf, in->length);
@@ -248,7 +266,7 @@ krb5_error_code
 kr_attr_encode(krb5_context ctx, const char *secret,
                const unsigned char *auth, krad_attr type,
                const krb5_data *in, unsigned char outbuf[MAX_ATTRSIZE],
-               size_t *outlen)
+               size_t *outlen, krb5_boolean *is_fips)
 {
     krb5_error_code retval;
 
@@ -265,7 +283,8 @@ kr_attr_encode(krb5_context ctx, const char *secret,
         return 0;
     }
 
-    return attributes[type - 1].encode(ctx, secret, auth, in, outbuf, outlen);
+    return attributes[type - 1].encode(ctx, secret, auth, in, outbuf, outlen,
+                                       is_fips);
 }
 
 krb5_error_code
@@ -274,6 +293,7 @@ kr_attr_decode(krb5_context ctx, const char *secret, const unsigned char *auth,
                unsigned char outbuf[MAX_ATTRSIZE], size_t *outlen)
 {
     krb5_error_code retval;
+    krb5_boolean ignored;
 
     retval = kr_attr_valid(type, in);
     if (retval != 0)
@@ -288,7 +308,8 @@ kr_attr_decode(krb5_context ctx, const char *secret, const unsigned char *auth,
         return 0;
     }
 
-    return attributes[type - 1].decode(ctx, secret, auth, in, outbuf, outlen);
+    return attributes[type - 1].decode(ctx, secret, auth, in, outbuf, outlen,
+                                       &ignored);
 }
 
 krad_attr
diff --git a/src/lib/krad/attrset.c b/src/lib/krad/attrset.c
index 03c613716..d89982a13 100644
--- a/src/lib/krad/attrset.c
+++ b/src/lib/krad/attrset.c
@@ -167,7 +167,8 @@ krad_attrset_copy(const krad_attrset *set, krad_attrset **copy)
 krb5_error_code
 kr_attrset_encode(const krad_attrset *set, const char *secret,
                   const unsigned char *auth,
-                  unsigned char outbuf[MAX_ATTRSETSIZE], size_t *outlen)
+                  unsigned char outbuf[MAX_ATTRSETSIZE], size_t *outlen,
+                  krb5_boolean *is_fips)
 {
     unsigned char buffer[MAX_ATTRSIZE];
     krb5_error_code retval;
@@ -181,7 +182,7 @@ kr_attrset_encode(const krad_attrset *set, const char *secret,
 
     K5_TAILQ_FOREACH(a, &set->list, list) {
         retval = kr_attr_encode(set->ctx, secret, auth, a->type, &a->attr,
-                                buffer, &attrlen);
+                                buffer, &attrlen, is_fips);
         if (retval != 0)
             return retval;
 
diff --git a/src/lib/krad/internal.h b/src/lib/krad/internal.h
index 996a89372..a53ce31ce 100644
--- a/src/lib/krad/internal.h
+++ b/src/lib/krad/internal.h
@@ -49,6 +49,13 @@
 
 typedef struct krad_remote_st krad_remote;
 
+struct krad_packet_st {
+    char buffer[KRAD_PACKET_SIZE_MAX];
+    krad_attrset *attrset;
+    krb5_data pkt;
+    krb5_boolean is_fips;
+};
+
 /* Validate constraints of an attribute. */
 krb5_error_code
 kr_attr_valid(krad_attr type, const krb5_data *data);
@@ -57,7 +64,8 @@ kr_attr_valid(krad_attr type, const krb5_data *data);
 krb5_error_code
 kr_attr_encode(krb5_context ctx, const char *secret, const unsigned char *auth,
                krad_attr type, const krb5_data *in,
-               unsigned char outbuf[MAX_ATTRSIZE], size_t *outlen);
+               unsigned char outbuf[MAX_ATTRSIZE], size_t *outlen,
+               krb5_boolean *is_fips);
 
 /* Decode an attribute. */
 krb5_error_code
@@ -69,7 +77,8 @@ kr_attr_decode(krb5_context ctx, const char *secret, const unsigned char *auth,
 krb5_error_code
 kr_attrset_encode(const krad_attrset *set, const char *secret,
                   const unsigned char *auth,
-                  unsigned char outbuf[MAX_ATTRSETSIZE], size_t *outlen);
+                  unsigned char outbuf[MAX_ATTRSETSIZE], size_t *outlen,
+                  krb5_boolean *is_fips);
 
 /* Decode attributes from a buffer. */
 krb5_error_code
diff --git a/src/lib/krad/packet.c b/src/lib/krad/packet.c
index c597174b6..794ac84c4 100644
--- a/src/lib/krad/packet.c
+++ b/src/lib/krad/packet.c
@@ -32,6 +32,7 @@
 #include <string.h>
 
 #include <arpa/inet.h>
+#include <openssl/crypto.h>
 
 typedef unsigned char uchar;
 
@@ -53,12 +54,6 @@ typedef unsigned char uchar;
 #define pkt_auth(p) ((uchar *)offset(&(p)->pkt, OFFSET_AUTH))
 #define pkt_attr(p) ((unsigned char *)offset(&(p)->pkt, OFFSET_ATTR))
 
-struct krad_packet_st {
-    char buffer[KRAD_PACKET_SIZE_MAX];
-    krad_attrset *attrset;
-    krb5_data pkt;
-};
-
 typedef struct {
     uchar x[(UCHAR_MAX + 1) / 8];
 } idmap;
@@ -187,8 +182,13 @@ auth_generate_response(krb5_context ctx, const char *secret,
     memcpy(data.data + response->pkt.length, secret, strlen(secret));
 
     /* Hash it. */
-    retval = krb5_c_make_checksum(ctx, CKSUMTYPE_RSA_MD5, NULL, 0, &data,
-                                  &hash);
+    if (FIPS_mode()) {
+        /* This checksum does very little security-wise anyway, so don't
+         * taint. */
+        hash.contents = calloc(1, AUTH_FIELD_SIZE);
+    } else
+        retval = krb5_c_make_checksum(ctx, CKSUMTYPE_RSA_MD5, NULL, 0, &data,
+                                      &hash);
     free(data.data);
     if (retval != 0)
         return retval;
@@ -276,7 +276,7 @@ krad_packet_new_request(krb5_context ctx, const char *secret, krad_code code,
 
     /* Encode the attributes. */
     retval = kr_attrset_encode(set, secret, pkt_auth(pkt), pkt_attr(pkt),
-                               &attrset_len);
+                               &attrset_len, &pkt->is_fips);
     if (retval != 0)
         goto error;
 
@@ -314,7 +314,7 @@ krad_packet_new_response(krb5_context ctx, const char *secret, krad_code code,
 
     /* Encode the attributes. */
     retval = kr_attrset_encode(set, secret, pkt_auth(request), pkt_attr(pkt),
-                               &attrset_len);
+                               &attrset_len, &pkt->is_fips);
     if (retval != 0)
         goto error;
 
@@ -451,6 +451,8 @@ krad_packet_decode_response(krb5_context ctx, const char *secret,
 const krb5_data *
 krad_packet_encode(const krad_packet *pkt)
 {
+    if (pkt->is_fips)
+        return NULL;
     return &pkt->pkt;
 }
 
diff --git a/src/lib/krad/remote.c b/src/lib/krad/remote.c
index 437f7e91a..0f90443ce 100644
--- a/src/lib/krad/remote.c
+++ b/src/lib/krad/remote.c
@@ -263,7 +263,7 @@ on_io_write(krad_remote *rr)
     request *r;
 
     K5_TAILQ_FOREACH(r, &rr->list, list) {
-        tmp = krad_packet_encode(r->request);
+        tmp = &r->request->pkt;
 
         /* If the packet has already been sent, do nothing. */
         if (r->sent == tmp->length)
@@ -359,7 +359,7 @@ on_io_read(krad_remote *rr)
     if (req != NULL) {
         K5_TAILQ_FOREACH(r, &rr->list, list) {
             if (r->request == req &&
-                r->sent == krad_packet_encode(req)->length) {
+                r->sent == req->pkt.length) {
                 request_finish(r, 0, rsp);
                 break;
             }
@@ -455,6 +455,12 @@ kr_remote_send(krad_remote *rr, krad_code code, krad_attrset *attrs,
                                      (krad_packet_iter_cb)iterator, &r, &tmp);
     if (retval != 0)
         goto error;
+    else if (tmp->is_fips && rr->info->ai_family != AF_LOCAL &&
+        rr->info->ai_family != AF_UNIX) {
+        /* This would expose cleartext passwords, so abort. */
+        retval = ESOCKTNOSUPPORT;
+        goto error;
+    }
 
     K5_TAILQ_FOREACH(r, &rr->list, list) {
         if (r->request == tmp) {
diff --git a/src/lib/krad/t_attr.c b/src/lib/krad/t_attr.c
index eb2a780c8..4d285ad9d 100644
--- a/src/lib/krad/t_attr.c
+++ b/src/lib/krad/t_attr.c
@@ -50,6 +50,7 @@ main()
     const char *tmp;
     krb5_data in;
     size_t len;
+    krb5_boolean is_fips = FALSE;
 
     noerror(krb5_init_context(&ctx));
 
@@ -73,7 +74,7 @@ main()
     in = string2data((char *)decoded);
     retval = kr_attr_encode(ctx, secret, auth,
                             krad_attr_name2num("User-Password"),
-                            &in, outbuf, &len);
+                            &in, outbuf, &len, &is_fips);
     insist(retval == 0);
     insist(len == sizeof(encoded));
     insist(memcmp(outbuf, encoded, len) == 0);
diff --git a/src/lib/krad/t_attrset.c b/src/lib/krad/t_attrset.c
index 7928335ca..0f9576253 100644
--- a/src/lib/krad/t_attrset.c
+++ b/src/lib/krad/t_attrset.c
@@ -49,6 +49,7 @@ main()
     krb5_context ctx;
     size_t len = 0, encode_len;
     krb5_data tmp;
+    krb5_boolean is_fips = FALSE;
 
     noerror(krb5_init_context(&ctx));
     noerror(krad_attrset_new(ctx, &set));
@@ -62,7 +63,8 @@ main()
     noerror(krad_attrset_add(set, krad_attr_name2num("User-Password"), &tmp));
 
     /* Encode attrset. */
-    noerror(kr_attrset_encode(set, "foo", auth, buffer, &encode_len));
+    noerror(kr_attrset_encode(set, "foo", auth, buffer, &encode_len,
+                              &is_fips));
     krad_attrset_free(set);
 
     /* Manually encode User-Name. */