From e7266b788278f019ad15d2d2fe518401e98c5645 Mon Sep 17 00:00:00 2001

From: Robbie Harwood <rharwood@redhat.com>

Date: Tue, 31 Jul 2018 13:47:26 -0400

Subject: [PATCH] In FIPS mode, add plaintext fallback for RC4 usages and taint

---

 src/lib/krad/attr.c      | 38 ++++++++++++++++++++++++++++----------

 src/lib/krad/attrset.c   |  5 +++--

 src/lib/krad/internal.h  | 13 +++++++++++--

 src/lib/krad/packet.c    | 18 +++++++++---------

 src/lib/krad/remote.c    | 10 ++++++++--

 src/lib/krad/t_attr.c    |  3 ++-

 src/lib/krad/t_attrset.c |  4 +++-

 7 files changed, 64 insertions(+), 27 deletions(-)

diff --git a/src/lib/krad/attr.c b/src/lib/krad/attr.c

index 9c13d9d75..f96153e2e 100644

--- a/src/lib/krad/attr.c

+++ b/src/lib/krad/attr.c

@@ -38,7 +38,8 @@

 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 +52,14 @@ 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 +131,8 @@ 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;

@@ -156,7 +160,12 @@ user_password_encode(krb5_context ctx, const char *secret,

         retval = krb5_c_make_checksum(ctx, CKSUMTYPE_RSA_MD5, NULL, 0, &tmp,

                                       &sum);

-        if (retval != 0) {

+        if (retval == ENOMEM) {

+            /* I'm Linux, so we know this is a FIPS failure.  RSA_MD5 doesn't

+             * provide security so let's move on. */

+            *is_fips = TRUE;

+            sum.contents = calloc(1, BLOCKSIZE);

+        } else if (retval != 0) {

             zap(tmp.data, tmp.length);

             zap(outbuf, len);

             krb5_free_data_contents(ctx, &tmp);

@@ -180,7 +189,8 @@ 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;

@@ -206,7 +216,12 @@ user_password_decode(krb5_context ctx, const char *secret,

         retval = krb5_c_make_checksum(ctx, CKSUMTYPE_RSA_MD5, NULL, 0,

                                       &tmp, &sum);

-        if (retval != 0) {

+        if (retval == ENOMEM) {

+            /* I'm Linux, so we know this is a FIPS failure.  Assume the

+             * other side is running locally and move on. */

+            *is_fips = TRUE;

+            sum.contents = calloc(1, BLOCKSIZE);

+        } else if (retval != 0) {

             zap(tmp.data, tmp.length);

             zap(outbuf, in->length);

             krb5_free_data_contents(ctx, &tmp);

@@ -248,7 +263,7 @@ 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 +280,8 @@ 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 +290,7 @@ 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 +305,8 @@ 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..2fbf0ee1e 100644

--- a/src/lib/krad/packet.c

+++ b/src/lib/krad/packet.c

@@ -53,12 +53,6 @@ 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;

@@ -190,7 +184,11 @@ auth_generate_response(krb5_context ctx, const char *secret,

     retval = krb5_c_make_checksum(ctx, CKSUMTYPE_RSA_MD5, NULL, 0, &data,

                                   &hash);

     free(data.data);

-    if (retval != 0)

+    if (retval == ENOMEM) {

+        /* We're on Linux, so this is a FIPS failure, and this checksum

+         * does very little security-wise anyway, so don't taint. */

+        hash.contents = calloc(1, AUTH_FIELD_SIZE);

+    } else if (retval != 0)

         return retval;

     memcpy(rauth, hash.contents, AUTH_FIELD_SIZE);

@@ -276,7 +274,7 @@ 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 +312,7 @@ 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 +449,8 @@ 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. */