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From bb5552ece2a351dc3ccab52cceea1eaffeacd768 Mon Sep 17 00:00:00 2001
From: Greg Hudson <ghudson@mit.edu>
Date: Mon, 14 Dec 2020 13:16:17 -0500
Subject: [PATCH] Add support for start_realm cache config
When making TGS requests, if start_realm is set in the cache, use the
named realm to look up the initial TGT for referral or cross-realm
requests. (Also correct a comment in struct _tkt_creds_context: the
ccache field is an owner pointer, not an alias.)
Add an internal API k5_cc_store_primary_cred(), which sets start_realm
if the cred being stored is a TGT for a realm other than the client
realm. Use this API when acquiring initial tickets with a
caller-specified output ccache, when renewing or validating tickets
with kinit, when accepting a delegated credential in a GSS context,
and when storing a single cred with kvno --out-cache.
ticket: 8332
tags: pullup
target_version: 1.19
(cherry picked from commit 0d56740ab9fcc40dc7f46c6fbebdf8f1214f9d96)
[rharwood@redhat.com: backport around spelling and canonicalization fallback]
---
doc/formats/ccache_file_format.rst | 6 +++++
src/clients/kinit/kinit.c | 2 +-
src/clients/kvno/kvno.c | 5 ++++-
src/include/k5-int.h | 4 ++++
src/lib/gssapi/krb5/accept_sec_context.c | 2 +-
src/lib/krb5/ccache/ccfns.c | 20 +++++++++++++++++
src/lib/krb5/krb/get_creds.c | 28 ++++++++++++++++++------
src/lib/krb5/krb/get_in_tkt.c | 2 +-
src/lib/krb5/libkrb5.exports | 1 +
src/lib/krb5_32.def | 3 +++
src/tests/t_crossrealm.py | 8 +++++++
src/tests/t_pkinit.py | 3 +++
12 files changed, 73 insertions(+), 11 deletions(-)
diff --git a/doc/formats/ccache_file_format.rst b/doc/formats/ccache_file_format.rst
index 6349e0d29..6138c1b58 100644
--- a/doc/formats/ccache_file_format.rst
+++ b/doc/formats/ccache_file_format.rst
@@ -174,3 +174,9 @@ refresh_time
decimal representation of a timestamp at which the GSS mechanism
should attempt to refresh the credential cache from the client
keytab.
+
+start_realm
+ This key indicates the realm of the ticket-granting ticket to be
+ used for TGS requests, when making a referrals request or
+ beginning a cross-realm request. If it is not present, the client
+ realm is used.
diff --git a/src/clients/kinit/kinit.c b/src/clients/kinit/kinit.c
index 3fdae2878..e5ebeb895 100644
--- a/src/clients/kinit/kinit.c
+++ b/src/clients/kinit/kinit.c
@@ -828,7 +828,7 @@ k5_kinit(struct k_opts *opts, struct k5_data *k5)
if (opts->verbose)
fprintf(stderr, _("Initialized cache\n"));
- ret = krb5_cc_store_cred(k5->ctx, k5->out_cc, &my_creds);
+ ret = k5_cc_store_primary_cred(k5->ctx, k5->out_cc, &my_creds);
if (ret) {
com_err(progname, ret, _("while storing credentials"));
goto cleanup;
diff --git a/src/clients/kvno/kvno.c b/src/clients/kvno/kvno.c
index c5f6bf700..f83c68a99 100644
--- a/src/clients/kvno/kvno.c
+++ b/src/clients/kvno/kvno.c
@@ -561,7 +561,10 @@ do_v5_kvno(int count, char *names[], char * ccachestr, char *etypestr,
}
initialized = 1;
}
- ret = krb5_cc_store_cred(context, out_ccache, creds);
+ if (count == 1)
+ ret = k5_cc_store_primary_cred(context, out_ccache, creds);
+ else
+ ret = krb5_cc_store_cred(context, out_ccache, creds);
if (ret) {
com_err(prog, ret, _("while storing creds in output ccache"));
exit(1);
diff --git a/src/include/k5-int.h b/src/include/k5-int.h
index eb18a4cd6..912aaedac 100644
--- a/src/include/k5-int.h
+++ b/src/include/k5-int.h
@@ -307,6 +307,7 @@ typedef unsigned char u_char;
#define KRB5_CC_CONF_PA_TYPE "pa_type"
#define KRB5_CC_CONF_PROXY_IMPERSONATOR "proxy_impersonator"
#define KRB5_CC_CONF_REFRESH_TIME "refresh_time"
+#define KRB5_CC_CONF_START_REALM "start_realm"
/* Error codes used in KRB_ERROR protocol messages.
Return values of library routines are based on a different error table
@@ -1910,6 +1911,9 @@ krb5_ser_unpack_bytes(krb5_octet *, size_t, krb5_octet **, size_t *);
krb5_error_code KRB5_CALLCONV
krb5int_cc_default(krb5_context, krb5_ccache *);
+krb5_error_code
+k5_cc_store_primary_cred(krb5_context, krb5_ccache, krb5_creds *);
+
/* Fill in the buffer with random alpha-numeric data. */
krb5_error_code
krb5int_random_string(krb5_context, char *string, unsigned int length);
diff --git a/src/lib/gssapi/krb5/accept_sec_context.c b/src/lib/gssapi/krb5/accept_sec_context.c
index 3d5b84b15..abccb5d11 100644
--- a/src/lib/gssapi/krb5/accept_sec_context.c
+++ b/src/lib/gssapi/krb5/accept_sec_context.c
@@ -216,7 +216,7 @@ rd_and_store_for_creds(context, auth_context, inbuf, out_cred)
if ((retval = krb5_cc_initialize(context, ccache, creds[0]->client)))
goto cleanup;
- if ((retval = krb5_cc_store_cred(context, ccache, creds[0])))
+ if ((retval = k5_cc_store_primary_cred(context, ccache, creds[0])))
goto cleanup;
/* generate a delegated credential handle */
diff --git a/src/lib/krb5/ccache/ccfns.c b/src/lib/krb5/ccache/ccfns.c
index 62a6983d8..23edc2578 100644
--- a/src/lib/krb5/ccache/ccfns.c
+++ b/src/lib/krb5/ccache/ccfns.c
@@ -297,3 +297,23 @@ krb5_cc_switch(krb5_context context, krb5_ccache cache)
return 0;
return cache->ops->switch_to(context, cache);
}
+
+krb5_error_code
+k5_cc_store_primary_cred(krb5_context context, krb5_ccache cache,
+ krb5_creds *creds)
+{
+ krb5_error_code ret;
+
+ /* Write a start realm if we're writing a TGT and the client realm isn't
+ * the same as the TGS realm. */
+ if (IS_TGS_PRINC(creds->server) &&
+ !data_eq(creds->client->realm, creds->server->data[1])) {
+ ret = krb5_cc_set_config(context, cache, NULL,
+ KRB5_CC_CONF_START_REALM,
+ &creds->server->data[1]);
+ if (ret)
+ return ret;
+ }
+
+ return krb5_cc_store_cred(context, cache, creds);
+}
diff --git a/src/lib/krb5/krb/get_creds.c b/src/lib/krb5/krb/get_creds.c
index e0a3b5cd8..b40f705fc 100644
--- a/src/lib/krb5/krb/get_creds.c
+++ b/src/lib/krb5/krb/get_creds.c
@@ -149,7 +149,8 @@ struct _krb5_tkt_creds_context {
krb5_principal client; /* Caller-requested client principal (alias) */
krb5_principal server; /* Server principal (alias) */
krb5_principal req_server; /* Caller-requested server principal */
- krb5_ccache ccache; /* Caller-provided ccache (alias) */
+ krb5_ccache ccache; /* Caller-provided ccache */
+ krb5_data start_realm; /* Realm of starting TGT in ccache */
krb5_flags req_options; /* Caller-requested KRB5_GC_* options */
krb5_flags req_kdcopt; /* Caller-requested options as KDC options */
krb5_authdata **authdata; /* Caller-requested authdata */
@@ -783,7 +784,7 @@ get_cached_local_tgt(krb5_context context, krb5_tkt_creds_context ctx,
return code;
/* Construct the principal name. */
- code = krb5int_tgtname(context, &ctx->client->realm, &ctx->client->realm,
+ code = krb5int_tgtname(context, &ctx->start_realm, &ctx->start_realm,
&tgtname);
if (code != 0)
return code;
@@ -821,7 +822,7 @@ init_realm_path(krb5_context context, krb5_tkt_creds_context ctx)
size_t nrealms;
/* Get the client realm path and count its length. */
- code = k5_client_realm_path(context, &ctx->client->realm,
+ code = k5_client_realm_path(context, &ctx->start_realm,
&ctx->server->realm, &realm_path);
if (code != 0)
return code;
@@ -933,7 +934,7 @@ step_get_tgt(krb5_context context, krb5_tkt_creds_context ctx)
ctx->cur_realm = path_realm;
ctx->next_realm = ctx->last_realm;
}
- } else if (data_eq(*tgt_realm, ctx->client->realm)) {
+ } else if (data_eq(*tgt_realm, ctx->start_realm)) {
/* We were referred back to the local realm, which is bad. */
return KRB5_KDCREP_MODIFIED;
} else {
@@ -963,7 +964,7 @@ begin_get_tgt(krb5_context context, krb5_tkt_creds_context ctx)
ctx->state = STATE_GET_TGT;
- is_local_service = data_eq(ctx->client->realm, ctx->server->realm);
+ is_local_service = data_eq(ctx->start_realm, ctx->server->realm);
if (!is_local_service) {
/* See if we have a cached TGT for the server realm. */
code = get_cached_tgt(context, ctx, &ctx->server->realm, &cached_tgt);
@@ -1048,10 +1049,10 @@ begin(krb5_context context, krb5_tkt_creds_context ctx)
if (code != 0 || ctx->state == STATE_COMPLETE)
return code;
- /* If the server realm is unspecified, start with the client realm. */
+ /* If the server realm is unspecified, start with the TGT realm. */
if (krb5_is_referral_realm(&ctx->server->realm)) {
krb5_free_data_contents(context, &ctx->server->realm);
- code = krb5int_copy_data_contents(context, &ctx->client->realm,
+ code = krb5int_copy_data_contents(context, &ctx->start_realm,
&ctx->server->realm);
TRACE_TKT_CREDS_REFERRAL_REALM(context, ctx->server);
if (code != 0)
@@ -1100,6 +1101,18 @@ krb5_tkt_creds_init(krb5_context context, krb5_ccache ccache,
code = krb5_cc_dup(context, ccache, &ctx->ccache);
if (code != 0)
goto cleanup;
+
+ /* Get the start realm from the cache config, defaulting to the client
+ * realm. */
+ code = krb5_cc_get_config(context, ccache, NULL, "start_realm",
+ &ctx->start_realm);
+ if (code != 0) {
+ code = krb5int_copy_data_contents(context, &ctx->client->realm,
+ &ctx->start_realm);
+ if (code != 0)
+ goto cleanup;
+ }
+
code = krb5_copy_authdata(context, in_creds->authdata, &ctx->authdata);
if (code != 0)
goto cleanup;
@@ -1139,6 +1152,7 @@ krb5_tkt_creds_free(krb5_context context, krb5_tkt_creds_context ctx)
krb5int_fast_free_state(context, ctx->fast_state);
krb5_free_creds(context, ctx->in_creds);
krb5_cc_close(context, ctx->ccache);
+ krb5_free_data_contents(context, &ctx->start_realm);
krb5_free_principal(context, ctx->req_server);
krb5_free_authdata(context, ctx->authdata);
krb5_free_creds(context, ctx->cur_tgt);
diff --git a/src/lib/krb5/krb/get_in_tkt.c b/src/lib/krb5/krb/get_in_tkt.c
index cc0f70e83..f5dd7518b 100644
--- a/src/lib/krb5/krb/get_in_tkt.c
+++ b/src/lib/krb5/krb/get_in_tkt.c
@@ -1779,7 +1779,7 @@ init_creds_step_reply(krb5_context context,
code = krb5_cc_initialize(context, out_ccache, ctx->cred.client);
if (code != 0)
goto cc_cleanup;
- code = krb5_cc_store_cred(context, out_ccache, &ctx->cred);
+ code = k5_cc_store_primary_cred(context, out_ccache, &ctx->cred);
if (code != 0)
goto cc_cleanup;
if (fast_avail) {
diff --git a/src/lib/krb5/libkrb5.exports b/src/lib/krb5/libkrb5.exports
index 5aba29ee4..cab5b3b17 100644
--- a/src/lib/krb5/libkrb5.exports
+++ b/src/lib/krb5/libkrb5.exports
@@ -125,6 +125,7 @@ k5_add_pa_data_from_data
k5_alloc_pa_data
k5_authind_decode
k5_build_conf_principals
+k5_cc_store_primary_cred
k5_ccselect_free_context
k5_change_error_message_code
k5_etypes_contains
diff --git a/src/lib/krb5_32.def b/src/lib/krb5_32.def
index a0734c729..de5823c17 100644
--- a/src/lib/krb5_32.def
+++ b/src/lib/krb5_32.def
@@ -499,3 +499,6 @@ EXPORTS
k5_size_context @467 ; PRIVATE GSSAPI
k5_size_keyblock @468 ; PRIVATE GSSAPI
k5_size_principal @469 ; PRIVATE GSSAPI
+
+; new in 1.19
+ k5_cc_store_primary_cred @470 ; PRIVATE
diff --git a/src/tests/t_crossrealm.py b/src/tests/t_crossrealm.py
index fa7fd2604..28b397cfb 100755
--- a/src/tests/t_crossrealm.py
+++ b/src/tests/t_crossrealm.py
@@ -77,6 +77,14 @@ r1, r2, r3 = cross_realms(3, xtgts=((0,1), (1,2)),
{'realm': 'B.X'}))
test_kvno(r1, r3.host_princ, 'KDC domain walk')
check_klist(r1, (tgt(r1, r1), r3.host_princ))
+
+# Test start_realm in this setup.
+r1.run([kvno, '--out-cache', r1.ccache, r2.krbtgt_princ])
+r1.run([klist, '-C'], expected_msg='config: start_realm = X')
+msgs = ('Requesting TGT krbtgt/B.X@X using TGT krbtgt/X@X',
+ 'Received TGT for service realm: krbtgt/B.X@X')
+r1.run([kvno, r3.host_princ], expected_trace=msgs)
+
stop(r1, r2, r3)
# Test client capaths. The client in A will ask for a cross TGT to D,
diff --git a/src/tests/t_pkinit.py b/src/tests/t_pkinit.py
index ecd450e8a..f224383c8 100755
--- a/src/tests/t_pkinit.py
+++ b/src/tests/t_pkinit.py
@@ -130,6 +130,9 @@ realm.run([kvno, realm.host_princ])
out = realm.run(['./adata', realm.host_princ])
if '97:' in out:
fail('auth indicators seen in anonymous PKINIT ticket')
+# Verify start_realm setting and test referrals TGS request.
+realm.run([klist, '-C'], expected_msg='start_realm = KRBTEST.COM')
+realm.run([kvno, '-S', 'host', hostname])
# Test anonymous kadmin.
mark('anonymous kadmin')
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