[SCM] Samba Shared Repository - branch master updated

Alexander Bokovoy ab at samba.org
Wed Mar 8 21:01:02 UTC 2017


The branch, master has been updated
       via  57286d5 s3-gse: move krb5 fallback to smb_gss_krb5_import_cred wrapper
       via  3d733d5 s3-gse: convert to use smb_gss_krb5_import_cred
       via  5201679 libads: convert to use smb_gss_krb5_import_cred
       via  ca8fd79 credentials_krb5: convert to use smb_gss_krb5_import_cred
       via  0e6e8dd lib/krb5_wrap: add smb_gss_krb5_import_cred wrapper
       via  d630a36 gssapi: check for gss_acquire_cred_from
      from  980eae0 s3-libads: Do not leak the msg on error

https://git.samba.org/?p=samba.git;a=shortlog;h=master


- Log -----------------------------------------------------------------
commit 57286d57732d49fdb8b8e21f584787cdbc917c32
Author: Alexander Bokovoy <ab at samba.org>
Date:   Wed Mar 8 12:38:49 2017 +0200

    s3-gse: move krb5 fallback to smb_gss_krb5_import_cred wrapper
    
    MIT krb5 1.9 version of gss_krb5_import_cred() may fail when importing
    credentials from a keytab without specifying actual principal.
    This was fixed in MIT krb5 1.9.2 (see commit
    71c3be093db577aa52f6b9a9a3a9f442ca0d8f20 in MIT krb5-1.9 branch, git
    master's version is bd18687a705a8a6cdcb7c140764d1a7c6a3381b5).
    
    Move fallback code to the smb_gss_krb5_import_cred wrapper. We only
    expect this fallback to happen with krb5 GSSAPI mechanism, thus hard
    code use of krb5 mech when calling to gss_acquire_cred.
    
    BUG: https://bugzilla.samba.org/show_bug.cgi?id=12611
    
    Signed-off-by: Alexander Bokovoy <ab at samba.org>
    Reviewed-by: Stefan Metzmacher <metze at samba.org>
    
    Autobuild-User(master): Alexander Bokovoy <ab at samba.org>
    Autobuild-Date(master): Wed Mar  8 22:00:24 CET 2017 on sn-devel-144

commit 3d733d5791a6d82edda13ac39790bd8ba893f3d7
Author: Alexander Bokovoy <ab at samba.org>
Date:   Fri Mar 3 16:58:14 2017 +0200

    s3-gse: convert to use smb_gss_krb5_import_cred
    
    BUG: https://bugzilla.samba.org/show_bug.cgi?id=12611
    
    Signed-off-by: Alexander Bokovoy <ab at samba.org>
    Reviewed-by: Stefan Metzmacher <metze at samba.org>

commit 520167992bd2477bc11920d2dc9ec87f2cb339c9
Author: Alexander Bokovoy <ab at samba.org>
Date:   Fri Mar 3 16:57:50 2017 +0200

    libads: convert to use smb_gss_krb5_import_cred
    
    BUG: https://bugzilla.samba.org/show_bug.cgi?id=12611
    
    Signed-off-by: Alexander Bokovoy <ab at samba.org>
    Reviewed-by: Stefan Metzmacher <metze at samba.org>

commit ca8fd793930173b4e625d3f286739de214155bc1
Author: Alexander Bokovoy <ab at samba.org>
Date:   Fri Mar 3 16:57:13 2017 +0200

    credentials_krb5: convert to use smb_gss_krb5_import_cred
    
    BUG: https://bugzilla.samba.org/show_bug.cgi?id=12611
    
    Signed-off-by: Alexander Bokovoy <ab at samba.org>
    Reviewed-by: Stefan Metzmacher <metze at samba.org>

commit 0e6e8dd2600c699a7a02e3d11fed21b5bc49858d
Author: Alexander Bokovoy <ab at samba.org>
Date:   Fri Mar 3 16:14:57 2017 +0200

    lib/krb5_wrap: add smb_gss_krb5_import_cred wrapper
    
    Wrap gss_krb5_import_cred() to allow re-implementing it with
    gss_acquire_cred_from() for newer MIT versions. gss_acquire_cred_from()
    works fine with GSSAPI interposer (GSS-proxy) while
    gss_krb5_import_cred() is not interposed yet.
    
    The wrapper has additional parameter, krb5_context handle, to facilitate
    with credentials cache name discovery. All our callers to
    gss_krb5_import_cred() already have krb5 context handy.
    
    BUG: https://bugzilla.samba.org/show_bug.cgi?id=12611
    
    Signed-off-by: Alexander Bokovoy <ab at samba.org>
    Reviewed-by: Stefan Metzmacher <metze at samba.org>

commit d630a364f9d74443e482934f76cd7107c331e108
Author: Alexander Bokovoy <ab at samba.org>
Date:   Fri Mar 3 17:08:09 2017 +0200

    gssapi: check for gss_acquire_cred_from
    
    BUG: https://bugzilla.samba.org/show_bug.cgi?id=12611
    
    Signed-off-by: Alexander Bokovoy <ab at samba.org>
    Reviewed-by: Stefan Metzmacher <metze at samba.org>

-----------------------------------------------------------------------

Summary of changes:
 auth/credentials/credentials_krb5.c |  22 +++--
 lib/krb5_wrap/gss_samba.c           | 161 ++++++++++++++++++++++++++++++++++++
 lib/krb5_wrap/gss_samba.h           |  13 +++
 source3/libads/sasl.c               |   2 +-
 source3/librpc/crypto/gse.c         |  69 +++-------------
 wscript_configure_system_mitkrb5    |   1 +
 6 files changed, 201 insertions(+), 67 deletions(-)


Changeset truncated at 500 lines:

diff --git a/auth/credentials/credentials_krb5.c b/auth/credentials/credentials_krb5.c
index d2a655e..6544e42 100644
--- a/auth/credentials/credentials_krb5.c
+++ b/auth/credentials/credentials_krb5.c
@@ -717,8 +717,9 @@ _PUBLIC_ int cli_credentials_get_client_gss_creds(struct cli_credentials *cred,
 		return ENOMEM;
 	}
 
-	maj_stat = gss_krb5_import_cred(&min_stat, ccache->ccache, NULL, NULL, 
-					&gcc->creds);
+	maj_stat = smb_gss_krb5_import_cred(&min_stat, ccache->smb_krb5_context->krb5_context,
+					    ccache->ccache, NULL, NULL,
+					    &gcc->creds);
 	if ((maj_stat == GSS_S_FAILURE) &&
 	    (min_stat == (OM_uint32)KRB5_CC_END ||
 	     min_stat == (OM_uint32)KRB5_CC_NOTFOUND ||
@@ -735,8 +736,9 @@ _PUBLIC_ int cli_credentials_get_client_gss_creds(struct cli_credentials *cred,
 			return ret;
 		}
 
-		maj_stat = gss_krb5_import_cred(&min_stat, ccache->ccache, NULL, NULL,
-						&gcc->creds);
+		maj_stat = smb_gss_krb5_import_cred(&min_stat, ccache->smb_krb5_context->krb5_context,
+						    ccache->ccache, NULL, NULL,
+						    &gcc->creds);
 
 	}
 
@@ -747,7 +749,7 @@ _PUBLIC_ int cli_credentials_get_client_gss_creds(struct cli_credentials *cred,
 		} else {
 			ret = EINVAL;
 		}
-		(*error_string) = talloc_asprintf(cred, "gss_krb5_import_cred failed: %s", error_message(ret));
+		(*error_string) = talloc_asprintf(cred, "smb_gss_krb5_import_cred failed: %s", error_message(ret));
 		return ret;
 	}
 
@@ -1215,12 +1217,14 @@ _PUBLIC_ int cli_credentials_get_server_gss_creds(struct cli_credentials *cred,
 
 	if (ktc->password_based || obtained < CRED_SPECIFIED) {
 		/* This creates a GSSAPI cred_id_t for match-by-key with only the keytab set */
-		maj_stat = gss_krb5_import_cred(&min_stat, NULL, NULL, ktc->keytab,
-						&gcc->creds);
+		maj_stat = smb_gss_krb5_import_cred(&min_stat, smb_krb5_context->krb5_context,
+						    NULL, NULL, ktc->keytab,
+						    &gcc->creds);
 	} else {
 		/* This creates a GSSAPI cred_id_t with the principal and keytab set, matching by name */
-		maj_stat = gss_krb5_import_cred(&min_stat, NULL, princ, ktc->keytab,
-						&gcc->creds);
+		maj_stat = smb_gss_krb5_import_cred(&min_stat, smb_krb5_context->krb5_context,
+						    NULL, princ, ktc->keytab,
+						    &gcc->creds);
 	}
 	if (maj_stat) {
 		if (min_stat) {
diff --git a/lib/krb5_wrap/gss_samba.c b/lib/krb5_wrap/gss_samba.c
index b444633..9e5ad4a 100644
--- a/lib/krb5_wrap/gss_samba.c
+++ b/lib/krb5_wrap/gss_samba.c
@@ -48,4 +48,165 @@ int smb_gss_oid_equal(const gss_OID first_oid, const gss_OID second_oid)
 }
 #endif /* !HAVE_GSS_OID_EQUAL */
 
+
+/* wrapper around gss_krb5_import_cred() that prefers to use gss_acquire_cred_from()
+ * if this GSSAPI extension is available. gss_acquire_cred_from() is properly
+ * interposed by GSSPROXY while gss_krb5_import_cred() is not.
+ *
+ * This wrapper requires a proper krb5_context to resolve ccache name.
+ * All gss_krb5_import_cred() callers in Samba already have krb5_context available. */
+uint32_t smb_gss_krb5_import_cred(uint32_t *minor_status, krb5_context ctx,
+				  krb5_ccache id, krb5_principal keytab_principal,
+				  krb5_keytab keytab, gss_cred_id_t *cred)
+{
+	uint32_t major_status = 0;
+
+#if HAVE_GSS_ACQUIRE_CRED_FROM
+	uint32_t minor = 0;
+	gss_key_value_element_desc ccache_element = {
+		.key = "ccache",
+		.value = NULL,
+	};
+
+	gss_key_value_element_desc keytab_element = {
+		.key = "keytab",
+		.value = NULL,
+	};
+
+	gss_key_value_element_desc elements[2];
+
+	gss_key_value_set_desc cred_store = {
+		.elements = &ccache_element,
+		.count = 1,
+	};
+
+	gss_OID_set mech_set = GSS_C_NO_OID_SET;
+	gss_cred_usage_t cred_usage = GSS_C_INITIATE;
+	gss_name_t name = NULL;
+	gss_buffer_desc pr_name = {
+		.value = NULL,
+		.length = 0,
+	};
+
+	if (id != NULL) {
+		major_status = krb5_cc_get_full_name(ctx,
+						     id,
+						     discard_const(&ccache_element.value));
+		if (major_status != 0) {
+			return major_status;
+		}
+	}
+
+	if (keytab != NULL) {
+		keytab_element.value = malloc(4096);
+		if (!keytab_element.value) {
+			return ENOMEM;
+		}
+		major_status = krb5_kt_get_name(ctx,
+						keytab,
+						discard_const(keytab_element.value), 4096);
+		if (major_status != 0) {
+			free(discard_const(keytab_element.value));
+			return major_status;
+		}
+		cred_usage = GSS_C_ACCEPT;
+		cred_store.elements = &keytab_element;
+
+		if (keytab_principal != NULL) {
+			major_status = krb5_unparse_name(ctx, keytab_principal, (char**)&pr_name.value);
+			if (major_status != 0) {
+				free(discard_const(keytab_element.value));
+				return major_status;
+			}
+			pr_name.length = strlen(pr_name.value);
+
+			major_status = gss_import_name(minor_status,
+						       &pr_name,
+						       discard_const(GSS_KRB5_NT_PRINCIPAL_NAME),
+						       &name);
+			if (major_status != 0) {
+				krb5_free_unparsed_name(ctx, pr_name.value);
+				free(discard_const(keytab_element.value));
+				return major_status;
+			}
+		}
+	}
+
+	if (id != NULL && keytab != NULL) {
+		elements[0] = ccache_element;
+		elements[1] = keytab_element;
+
+		cred_store.elements = elements;
+		cred_store.count = 2;
+		cred_usage = GSS_C_BOTH;
+	}
+
+	major_status = gss_acquire_cred_from(minor_status,
+					     name,
+					     0,
+					     mech_set,
+					     cred_usage,
+					     &cred_store,
+					     cred,
+					     NULL,
+					     NULL);
+
+	if (pr_name.value != NULL) {
+		(void)gss_release_name(&minor, &name);
+		krb5_free_unparsed_name(ctx, pr_name.value);
+	}
+	if (keytab_element.value != NULL) {
+		free(discard_const(keytab_element.value));
+	}
+	krb5_free_string(ctx, discard_const(ccache_element.value));
+#else
+	major_status = gss_krb5_import_cred(minor_status,
+					    id,
+					    keytab_principal,
+					    keytab, cred);
+
+	if (major_status == (GSS_S_CALL_BAD_STRUCTURE|GSS_S_BAD_NAME)) {
+		if ((keytab_principal == NULL) && (keytab != NULL)) {
+			/* No principal was specified and MIT krb5 1.9 version failed.
+			 * We have to fall back to set global acceptor identity */
+			gss_OID_set_desc mech_set;
+			char *kt_name = NULL;
+
+			kt_name = malloc(4096);
+			if (!kt_name) {
+				return ENOMEM;
+			}
+
+			major_status = krb5_kt_get_name(ctx,
+							keytab,
+							kt_name, 4096);
+			if (major_status != 0) {
+				free(kt_name);
+				return major_status;
+			}
+
+			major_status = gsskrb5_register_acceptor_identity(kt_name);
+			if (major_status) {
+				free(kt_name);
+				return major_status;
+			}
+
+			/* We are dealing with krb5 GSSAPI mech in this fallback */
+			mech_set.count = 1;
+			mech_set.elements = gss_mech_krb5;
+			major_status = gss_acquire_cred(minor_status,
+							GSS_C_NO_NAME,
+							GSS_C_INDEFINITE,
+							&mech_set,
+							GSS_C_ACCEPT,
+							cred,
+							NULL, NULL);
+			free(kt_name);
+		}
+	}
+#endif
+	return major_status;
+}
+
+
 #endif /* HAVE_GSSAPI */
diff --git a/lib/krb5_wrap/gss_samba.h b/lib/krb5_wrap/gss_samba.h
index 5319932..89aee34 100644
--- a/lib/krb5_wrap/gss_samba.h
+++ b/lib/krb5_wrap/gss_samba.h
@@ -25,6 +25,7 @@
 #ifdef HAVE_GSSAPI
 
 #include "system/gssapi.h"
+#include "krb5_samba.h"
 
 #if defined(HAVE_GSS_OID_EQUAL)
 #define smb_gss_oid_equal gss_oid_equal
@@ -32,5 +33,17 @@
 int smb_gss_oid_equal(const gss_OID first_oid, const gss_OID second_oid);
 #endif /* HAVE_GSS_OID_EQUAL */
 
+/* wrapper around gss_krb5_import_cred() that prefers to use gss_acquire_cred_from()
+ * if this GSSAPI extension is available. gss_acquire_cred_from() is properly
+ * interposed by GSS-proxy while gss_krb5_import_cred() is not.
+ *
+ * This wrapper requires a proper krb5_context to resolve the ccache name for
+ * gss_acquire_cred_from().
+ *
+ * All gss_krb5_import_cred() callers in Samba already have krb5_context available. */
+uint32_t smb_gss_krb5_import_cred(OM_uint32 *minor_status, krb5_context ctx,
+				  krb5_ccache id, krb5_principal keytab_principal,
+				  krb5_keytab keytab, gss_cred_id_t *cred);
+
 #endif /* HAVE_GSSAPI */
 #endif /* _GSS_SAMBA_H */
diff --git a/source3/libads/sasl.c b/source3/libads/sasl.c
index cb630fa..ab79f70 100644
--- a/source3/libads/sasl.c
+++ b/source3/libads/sasl.c
@@ -371,7 +371,7 @@ static ADS_STATUS ads_init_gssapi_cred(ADS_STRUCT *ads, gss_cred_id_t *cred)
 		goto done;
 	}
 
-	maj = gss_krb5_import_cred(&min, kccache, NULL, NULL, cred);
+	maj = smb_gss_krb5_import_cred(&min, kctx, kccache, NULL, NULL, cred);
 	if (maj != GSS_S_COMPLETE) {
 		status = ADS_ERROR_GSS(maj, min);
 		goto done;
diff --git a/source3/librpc/crypto/gse.c b/source3/librpc/crypto/gse.c
index abf20bc..a111320 100644
--- a/source3/librpc/crypto/gse.c
+++ b/source3/librpc/crypto/gse.c
@@ -252,11 +252,12 @@ static NTSTATUS gse_init_client(TALLOC_CTX *mem_ctx,
 	/* TODO: get krb5 ticket using username/password, if no valid
 	 * one already available in ccache */
 
-	gss_maj = gss_krb5_import_cred(&gss_min,
-				       gse_ctx->ccache,
-				       NULL, /* keytab_principal */
-				       NULL, /* keytab */
-				       &gse_ctx->creds);
+	gss_maj = smb_gss_krb5_import_cred(&gss_min,
+					   gse_ctx->k5ctx,
+					   gse_ctx->ccache,
+					   NULL, /* keytab_principal */
+					   NULL, /* keytab */
+					   &gse_ctx->creds);
 	if (gss_maj) {
 		char *ccache = NULL;
 		int kret;
@@ -268,7 +269,7 @@ static NTSTATUS gse_init_client(TALLOC_CTX *mem_ctx,
 			ccache = NULL;
 		}
 
-		DEBUG(5, ("gss_krb5_import_cred ccache[%s] failed with [%s] -"
+		DEBUG(5, ("smb_gss_krb5_import_cred ccache[%s] failed with [%s] -"
 			  "the caller may retry after a kinit.\n",
 			  ccache, gse_errstr(gse_ctx, gss_maj, gss_min)));
 		SAFE_FREE(ccache);
@@ -430,61 +431,15 @@ static NTSTATUS gse_init_server(TALLOC_CTX *mem_ctx,
 	}
 
 	/* This creates a GSSAPI cred_id_t with the keytab set */
-	gss_maj = gss_krb5_import_cred(&gss_min, NULL, NULL, gse_ctx->keytab, 
-				       &gse_ctx->creds);
+	gss_maj = smb_gss_krb5_import_cred(&gss_min, gse_ctx->k5ctx,
+					   NULL, NULL, gse_ctx->keytab,
+					   &gse_ctx->creds);
 
-	if (gss_maj != 0
-	    && gss_maj != (GSS_S_CALL_BAD_STRUCTURE|GSS_S_BAD_NAME)) {
-		DEBUG(0, ("gss_krb5_import_cred failed with [%s]\n",
+	if (gss_maj != 0) {
+		DEBUG(0, ("smb_gss_krb5_import_cred failed with [%s]\n",
 			  gse_errstr(gse_ctx, gss_maj, gss_min)));
 		status = NT_STATUS_INTERNAL_ERROR;
 		goto done;
-
-		/* This is the error the MIT krb5 1.9 gives when it
-		 * implements the function, but we do not specify the
-		 * principal.  However, when we specify the principal
-		 * as host$@REALM the GSS acceptor fails with 'wrong
-		 * principal in request'.  Work around the issue by
-		 * falling back to the alternate approach below. */
-	} else if (gss_maj == (GSS_S_CALL_BAD_STRUCTURE|GSS_S_BAD_NAME))
-	/* FIXME!!!
-	 * This call sets the default keytab for the whole server, not
-	 * just for this context. Need to find a way that does not alter
-	 * the state of the whole server ... */
-	{
-		const char *ktname;
-		gss_OID_set_desc mech_set;
-
-		ret = smb_krb5_kt_get_name(gse_ctx, gse_ctx->k5ctx,
-				   gse_ctx->keytab, &ktname);
-		if (ret) {
-			status = NT_STATUS_INTERNAL_ERROR;
-			goto done;
-		}
-
-		ret = gsskrb5_register_acceptor_identity(ktname);
-		if (ret) {
-			status = NT_STATUS_INTERNAL_ERROR;
-			goto done;
-		}
-
-		mech_set.count = 1;
-		mech_set.elements = &gse_ctx->gss_mech;
-
-		gss_maj = gss_acquire_cred(&gss_min,
-				   GSS_C_NO_NAME,
-				   GSS_C_INDEFINITE,
-				   &mech_set,
-				   GSS_C_ACCEPT,
-				   &gse_ctx->creds,
-				   NULL, NULL);
-
-		if (gss_maj) {
-			DEBUG(0, ("gss_acquire_creds failed with [%s]\n",
-				  gse_errstr(gse_ctx, gss_maj, gss_min)));
-			status = NT_STATUS_INTERNAL_ERROR;
-			goto done;
-		}
 	}
 
 	status = NT_STATUS_OK;
diff --git a/wscript_configure_system_mitkrb5 b/wscript_configure_system_mitkrb5
index 06a9821..d3e8ebf 100644
--- a/wscript_configure_system_mitkrb5
+++ b/wscript_configure_system_mitkrb5
@@ -92,6 +92,7 @@ conf.CHECK_FUNCS_IN('''
        gsskrb5_extract_authz_data_from_sec_context
        gss_krb5_export_lucid_sec_context
        gss_import_cred gss_export_cred
+       gss_acquire_cred_from
        ''', 'gssapi gssapi_krb5')
 conf.CHECK_VARIABLE('GSS_KRB5_CRED_NO_CI_FLAGS_X', headers=possible_gssapi_headers)
 conf.CHECK_FUNCS_IN('krb5_mk_req_extended krb5_kt_compare', 'krb5')


-- 
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