1 files changed, 273 insertions, 4 deletions

diff --git a/gss-genr.c b/gss-genr.c
index d56257b4a..285fc29a5 100644
--- a/gss-genr.c
+++ b/gss-genr.c
@@ -1,7 +1,7 @@
 /* $OpenBSD: gss-genr.c,v 1.26 2018/07/10 09:13:30 djm Exp $ */
 
 /*
- * Copyright (c) 2001-2007 Simon Wilkinson. All rights reserved.
+ * Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -41,12 +41,34 @@
 #include "sshbuf.h"
 #include "log.h"
 #include "ssh2.h"
+#include "cipher.h"
+#include "kex.h"
+#include <openssl/evp.h>
 
 #include "ssh-gss.h"
 
 extern u_char *session_id2;
 extern u_int session_id2_len;
 
+typedef struct {
+        char *encoded;
+        gss_OID oid;
+} ssh_gss_kex_mapping;
+
+/*
+ * XXX - It would be nice to find a more elegant way of handling the
+ * XXX   passing of the key exchange context to the userauth routines
+ */
+
+Gssctxt *gss_kex_context = NULL;
+
+static ssh_gss_kex_mapping *gss_enc2oid = NULL;
+
+int 
+ssh_gssapi_oid_table_ok(void) {
+        return (gss_enc2oid != NULL);
+}
+
 /* sshbuf_get for gss_buffer_desc */
 int
 ssh_gssapi_get_buffer_desc(struct sshbuf *b, gss_buffer_desc *g)
@@ -62,6 +84,141 @@ ssh_gssapi_get_buffer_desc(struct sshbuf *b, gss_buffer_desc *g)
         return 0;
 }
 
+/*
+ * Return a list of the gss-group1-sha1 mechanisms supported by this program
+ *
+ * We test mechanisms to ensure that we can use them, to avoid starting
+ * a key exchange with a bad mechanism
+ */
+
+char *
+ssh_gssapi_client_mechanisms(const char *host, const char *client) {
+        gss_OID_set gss_supported;
+        OM_uint32 min_status;
+
+        if (GSS_ERROR(gss_indicate_mechs(&min_status, &gss_supported)))
+                return NULL;
+
+        return(ssh_gssapi_kex_mechs(gss_supported, ssh_gssapi_check_mechanism,
+            host, client));
+}
+
+char *
+ssh_gssapi_kex_mechs(gss_OID_set gss_supported, ssh_gssapi_check_fn *check,
+    const char *host, const char *client) {
+        struct sshbuf *buf;
+        size_t i;
+        int r, oidpos, enclen;
+        char *mechs, *encoded;
+        u_char digest[EVP_MAX_MD_SIZE];
+        char deroid[2];
+        const EVP_MD *evp_md = EVP_md5();
+        EVP_MD_CTX md;
+
+        if (gss_enc2oid != NULL) {
+                for (i = 0; gss_enc2oid[i].encoded != NULL; i++)
+                        free(gss_enc2oid[i].encoded);
+                free(gss_enc2oid);
+        }
+
+        gss_enc2oid = xmalloc(sizeof(ssh_gss_kex_mapping) *
+            (gss_supported->count + 1));
+
+        if ((buf = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
+
+        oidpos = 0;
+        for (i = 0; i < gss_supported->count; i++) {
+                if (gss_supported->elements[i].length < 128 &&
+                    (*check)(NULL, &(gss_supported->elements[i]), host, client)) {
+
+                        deroid[0] = SSH_GSS_OIDTYPE;
+                        deroid[1] = gss_supported->elements[i].length;
+
+                        EVP_DigestInit(&md, evp_md);
+                        EVP_DigestUpdate(&md, deroid, 2);
+                        EVP_DigestUpdate(&md,
+                            gss_supported->elements[i].elements,
+                            gss_supported->elements[i].length);
+                        EVP_DigestFinal(&md, digest, NULL);
+
+                        encoded = xmalloc(EVP_MD_size(evp_md) * 2);
+                        enclen = __b64_ntop(digest, EVP_MD_size(evp_md),
+                            encoded, EVP_MD_size(evp_md) * 2);
+
+                        if (oidpos != 0) {
+                                if ((r = sshbuf_put_u8(buf, ',')) != 0)
+                                        fatal("%s: buffer error: %s",
+                                            __func__, ssh_err(r));
+                        }
+
+                        if ((r = sshbuf_put(buf, KEX_GSS_GEX_SHA1_ID,
+                            sizeof(KEX_GSS_GEX_SHA1_ID) - 1)) != 0 ||
+                            (r = sshbuf_put(buf, encoded, enclen)) != 0 ||
+                            (r = sshbuf_put_u8(buf, ',')) != 0 ||
+                            (r = sshbuf_put(buf, KEX_GSS_GRP1_SHA1_ID,
+                            sizeof(KEX_GSS_GRP1_SHA1_ID) - 1)) != 0 ||
+                            (r = sshbuf_put(buf, encoded, enclen)) != 0 ||
+                            (r = sshbuf_put_u8(buf, ',')) != 0 ||
+                            (r = sshbuf_put(buf, KEX_GSS_GRP14_SHA1_ID,
+                            sizeof(KEX_GSS_GRP14_SHA1_ID) - 1)) != 0 ||
+                            (r = sshbuf_put(buf, encoded, enclen)) != 0)
+                                fatal("%s: buffer error: %s",
+                                    __func__, ssh_err(r));
+
+                        gss_enc2oid[oidpos].oid = &(gss_supported->elements[i]);
+                        gss_enc2oid[oidpos].encoded = encoded;
+                        oidpos++;
+                }
+        }
+        gss_enc2oid[oidpos].oid = NULL;
+        gss_enc2oid[oidpos].encoded = NULL;
+
+        if ((mechs = sshbuf_dup_string(buf)) == NULL)
+                fatal("%s: sshbuf_dup_string failed", __func__);
+
+        if (strlen(mechs) == 0) {
+                free(mechs);
+                mechs = NULL;
+        }
+        
+        return (mechs);
+}
+
+gss_OID
+ssh_gssapi_id_kex(Gssctxt *ctx, char *name, int kex_type) {
+        int i = 0;
+        
+        switch (kex_type) {
+        case KEX_GSS_GRP1_SHA1:
+                if (strlen(name) < sizeof(KEX_GSS_GRP1_SHA1_ID))
+                        return GSS_C_NO_OID;
+                name += sizeof(KEX_GSS_GRP1_SHA1_ID) - 1;
+                break;
+        case KEX_GSS_GRP14_SHA1:
+                if (strlen(name) < sizeof(KEX_GSS_GRP14_SHA1_ID))
+                        return GSS_C_NO_OID;
+                name += sizeof(KEX_GSS_GRP14_SHA1_ID) - 1;
+                break;
+        case KEX_GSS_GEX_SHA1:
+                if (strlen(name) < sizeof(KEX_GSS_GEX_SHA1_ID))
+                        return GSS_C_NO_OID;
+                name += sizeof(KEX_GSS_GEX_SHA1_ID) - 1;
+                break;
+        default:
+                return GSS_C_NO_OID;
+        }
+
+        while (gss_enc2oid[i].encoded != NULL &&
+            strcmp(name, gss_enc2oid[i].encoded) != 0)
+                i++;
+
+        if (gss_enc2oid[i].oid != NULL && ctx != NULL)
+                ssh_gssapi_set_oid(ctx, gss_enc2oid[i].oid);
+
+        return gss_enc2oid[i].oid;
+}
+
 /* Check that the OID in a data stream matches that in the context */
 int
 ssh_gssapi_check_oid(Gssctxt *ctx, void *data, size_t len)
@@ -218,7 +375,7 @@ ssh_gssapi_init_ctx(Gssctxt *ctx, int deleg_creds, gss_buffer_desc *recv_tok,
         }
 
         ctx->major = gss_init_sec_context(&ctx->minor,
-            GSS_C_NO_CREDENTIAL, &ctx->context, ctx->name, ctx->oid,
+            ctx->client_creds, &ctx->context, ctx->name, ctx->oid,
             GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG | deleg_flag,
             0, NULL, recv_tok, NULL, send_tok, flags, NULL);
 
@@ -248,8 +405,42 @@ ssh_gssapi_import_name(Gssctxt *ctx, const char *host)
 }
 
 OM_uint32
+ssh_gssapi_client_identity(Gssctxt *ctx, const char *name)
+{
+        gss_buffer_desc gssbuf;
+        gss_name_t gssname;
+        OM_uint32 status;
+        gss_OID_set oidset;
+
+        gssbuf.value = (void *) name;
+        gssbuf.length = strlen(gssbuf.value);
+
+        gss_create_empty_oid_set(&status, &oidset);
+        gss_add_oid_set_member(&status, ctx->oid, &oidset);
+
+        ctx->major = gss_import_name(&ctx->minor, &gssbuf,
+            GSS_C_NT_USER_NAME, &gssname);
+
+        if (!ctx->major)
+                ctx->major = gss_acquire_cred(&ctx->minor, 
+                    gssname, 0, oidset, GSS_C_INITIATE, 
+                    &ctx->client_creds, NULL, NULL);
+
+        gss_release_name(&status, &gssname);
+        gss_release_oid_set(&status, &oidset);
+
+        if (ctx->major)
+                ssh_gssapi_error(ctx);
+
+        return(ctx->major);
+}
+
+OM_uint32
 ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash)
 {
+        if (ctx == NULL) 
+                return -1;
+
         if ((ctx->major = gss_get_mic(&ctx->minor, ctx->context,
             GSS_C_QOP_DEFAULT, buffer, hash)))
                 ssh_gssapi_error(ctx);
@@ -257,6 +448,19 @@ ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash)
         return (ctx->major);
 }
 
+/* Priviledged when used by server */
+OM_uint32
+ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
+{
+        if (ctx == NULL)
+                return -1;
+
+        ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
+            gssbuf, gssmic, NULL);
+
+        return (ctx->major);
+}
+
 void
 ssh_gssapi_buildmic(struct sshbuf *b, const char *user, const char *service,
     const char *context)
@@ -273,11 +477,16 @@ ssh_gssapi_buildmic(struct sshbuf *b, const char *user, const char *service,
 }
 
 int
-ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host)
+ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host, 
+    const char *client)
 {
         gss_buffer_desc token = GSS_C_EMPTY_BUFFER;
         OM_uint32 major, minor;
         gss_OID_desc spnego_oid = {6, (void *)"\x2B\x06\x01\x05\x05\x02"};
+        Gssctxt *intctx = NULL;
+
+        if (ctx == NULL)
+                ctx = &intctx;
 
         /* RFC 4462 says we MUST NOT do SPNEGO */
         if (oid->length == spnego_oid.length && 
@@ -287,6 +496,10 @@ ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host)
         ssh_gssapi_build_ctx(ctx);
         ssh_gssapi_set_oid(*ctx, oid);
         major = ssh_gssapi_import_name(*ctx, host);
+
+        if (!GSS_ERROR(major) && client)
+                major = ssh_gssapi_client_identity(*ctx, client);
+
         if (!GSS_ERROR(major)) {
                 major = ssh_gssapi_init_ctx(*ctx, 0, GSS_C_NO_BUFFER, &token, 
                     NULL);
@@ -296,10 +509,66 @@ ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host)
                             GSS_C_NO_BUFFER);
         }
 
-        if (GSS_ERROR(major)) 
+        if (GSS_ERROR(major) || intctx != NULL) 
                 ssh_gssapi_delete_ctx(ctx);
 
         return (!GSS_ERROR(major));
 }
 
+int
+ssh_gssapi_credentials_updated(Gssctxt *ctxt) {
+        static gss_name_t saved_name = GSS_C_NO_NAME;
+        static OM_uint32 saved_lifetime = 0;
+        static gss_OID saved_mech = GSS_C_NO_OID;
+        static gss_name_t name;
+        static OM_uint32 last_call = 0;
+        OM_uint32 lifetime, now, major, minor;
+        int equal;
+        
+        now = time(NULL);
+
+        if (ctxt) {
+                debug("Rekey has happened - updating saved versions");
+
+                if (saved_name != GSS_C_NO_NAME)
+                        gss_release_name(&minor, &saved_name);
+
+                major = gss_inquire_cred(&minor, GSS_C_NO_CREDENTIAL,
+                    &saved_name, &saved_lifetime, NULL, NULL);
+
+                if (!GSS_ERROR(major)) {
+                        saved_mech = ctxt->oid;
+                        saved_lifetime+= now;
+                } else {
+                        /* Handle the error */
+                }
+                return 0;
+        }
+
+        if (now - last_call < 10)
+                return 0;
+
+        last_call = now;
+
+        if (saved_mech == GSS_C_NO_OID)
+                return 0;
+        
+        major = gss_inquire_cred(&minor, GSS_C_NO_CREDENTIAL, 
+            &name, &lifetime, NULL, NULL);
+        if (major == GSS_S_CREDENTIALS_EXPIRED)
+                return 0;
+        else if (GSS_ERROR(major))
+                return 0;
+
+        major = gss_compare_name(&minor, saved_name, name, &equal);
+        gss_release_name(&minor, &name);
+        if (GSS_ERROR(major))
+                return 0;
+
+        if (equal && (saved_lifetime < lifetime + now - 10))
+                return 1;
+
+        return 0;
+}
+
 #endif /* GSSAPI */