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authorSimo Sorce <simo@redhat.com>2013-11-13 12:29:26 -0500
committerAndreas Schneider <asn@cryptomilk.org>2013-11-15 14:49:29 +0100
commitc481f9dafdc7dc5c2eb105493f05846cf7425cec (patch)
tree67ade27ceb892f04196e7681cbeb3a5f178d46f1 /src/gssapi.c
parentf240ecf3287ccb96fbef95c37b530c6e6f677950 (diff)
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Fix gssapi credential handling.
- Properly acquire and inquitre credentials to get the list of available credentials. - Avoid enforcing a specific username it breaks some use cases (k5login). - Remove confusing references to delegated credentials as there is no code that actually uses delegated credentials in the initialization case. Signed-off-by: Siom Sorce <simo@redhat.com> Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
Diffstat (limited to 'src/gssapi.c')
-rw-r--r--src/gssapi.c170
1 files changed, 65 insertions, 105 deletions
diff --git a/src/gssapi.c b/src/gssapi.c
index c92c66cb..a0ab3646 100644
--- a/src/gssapi.c
+++ b/src/gssapi.c
@@ -57,6 +57,7 @@ struct ssh_gssapi_struct{
char *service; /* name of the service */
struct {
gss_name_t server_name; /* identity of server */
+ OM_uint32 flags; /* flags used for init context */
gss_OID oid; /* mech being used for authentication */
gss_cred_id_t client_deleg_creds; /* delegated creds (const, not freeable) */
} client;
@@ -616,85 +617,40 @@ fail:
return SSH_ERROR;
}
-/** @brief returns the OIDs of the mechs that work with both
- * hostname and username
+/** @brief returns the OIDs of the mechs that have usable credentials
*/
-static int ssh_gssapi_match(ssh_session session, char *hostname, char *username, gss_OID_set *valid_oids, int deleg){
- gss_buffer_desc host_namebuf, user_namebuf;
- gss_name_t host_name, user_name;
- OM_uint32 maj_stat, min_stat;
- gss_OID_set supported;
+static int ssh_gssapi_match(ssh_session session, gss_OID_set *valid_oids)
+{
+ OM_uint32 maj_stat, min_stat, lifetime;
+ gss_OID_set actual_mechs;
gss_OID oid;
- gss_ctx_id_t ctx = GSS_C_NO_CONTEXT;
- gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
- gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER;
- gss_cred_id_t client_creds = GSS_C_NO_CREDENTIAL;
unsigned int i;
char *ptr;
- char hostname_buf[256];
-
- gss_create_empty_oid_set(&min_stat, valid_oids);
- maj_stat = gss_indicate_mechs(&min_stat, &supported);
- for (i=0; i < supported->count; ++i){
- ptr=ssh_get_hexa(supported->elements[i].elements, supported->elements[i].length);
- SSH_LOG(SSH_LOG_DEBUG, "GSSAPI oid supported %d : %s\n",i, ptr);
- SAFE_FREE(ptr);
- }
-
- user_namebuf.value = username;
- user_namebuf.length = strlen(username) + 1;
- maj_stat = gss_import_name(&min_stat, &user_namebuf,
- (gss_OID) GSS_C_NT_USER_NAME, &user_name);
- if (maj_stat != GSS_S_COMPLETE) {
- SSH_LOG(SSH_LOG_DEBUG, "importing name %d, %d", maj_stat, min_stat);
- ssh_gssapi_log_error(SSH_LOG_DEBUG, "importing name", maj_stat);
- return -1;
+ maj_stat = gss_acquire_cred(&min_stat, GSS_C_NO_NAME, GSS_C_INDEFINITE,
+ GSS_C_NO_OID_SET, GSS_C_INITIATE,
+ &session->gssapi->client_creds,
+ &actual_mechs, NULL);
+ if (GSS_ERROR(maj_stat)) {
+ return SSH_ERROR;
}
- snprintf(hostname_buf, sizeof(hostname_buf),"host@%s", hostname);
- host_namebuf.value = hostname_buf;
- host_namebuf.length = strlen(hostname_buf) + 1;
- maj_stat = gss_import_name(&min_stat, &host_namebuf,
- (gss_OID) GSS_C_NT_HOSTBASED_SERVICE, &host_name);
- if (maj_stat != GSS_S_COMPLETE) {
- SSH_LOG(0, "importing name %d, %d", maj_stat, min_stat);
- ssh_gssapi_log_error(0, "importing name", maj_stat);
- return -1;
- }
+ gss_create_empty_oid_set(&min_stat, valid_oids);
- ssh_gssapi_init(session);
- session->gssapi->client_name = user_name;
- session->gssapi->client.server_name = host_name;
- session->gssapi->user = strdup(username);
- for (i=0; i<supported->count; ++i){
- oid = &supported->elements[i];
- maj_stat = gss_init_sec_context(&min_stat,
- session->gssapi->client.client_deleg_creds, &ctx, host_name, oid,
- GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG | (deleg ? GSS_C_DELEG_FLAG : 0),
- 0, NULL, &input_token, NULL, &output_token, NULL, NULL);
- if (!GSS_ERROR(maj_stat)){
- gss_OID_set tmp;
- if (session->gssapi->client.client_deleg_creds != GSS_C_NO_CREDENTIAL){
- /* we know the oid is ok since init_sec_context worked */
- gss_add_oid_set_member(&min_stat, oid, valid_oids);
- SSH_LOG(SSH_LOG_PROTOCOL, "Matched oid %u for server (with forwarding)", i);
- } else {
- gss_create_empty_oid_set(&min_stat, &tmp);
- gss_add_oid_set_member(&min_stat, oid, &tmp);
- maj_stat = gss_acquire_cred(&min_stat, user_name, 0,
- tmp, GSS_C_INITIATE,
- &client_creds, NULL, NULL);
- gss_release_oid_set(&min_stat, &tmp);
- if (!GSS_ERROR(maj_stat)){
- gss_release_cred(&min_stat, &client_creds);
- gss_add_oid_set_member(&min_stat,oid,valid_oids);
- SSH_LOG(SSH_LOG_PROTOCOL, "Matched oid %u for server", i);
- }
- }
+ /* double check each single cred */
+ for (i = 0; i < actual_mechs->count; i++) {
+ /* check lifetime is not 0 or skip */
+ lifetime = 0;
+ oid = &actual_mechs->elements[i];
+ maj_stat = gss_inquire_cred_by_mech(&min_stat,
+ session->gssapi->client_creds,
+ oid, NULL, &lifetime, NULL, NULL);
+ if (maj_stat == GSS_S_COMPLETE && lifetime > 0) {
+ gss_add_oid_set_member(&min_stat, oid, valid_oids);
+ ptr = ssh_get_hexa(oid->elements, oid->length);
+ SSH_LOG(SSH_LOG_DEBUG, "GSSAPI valid oid %d : %s\n", i, ptr);
+ SAFE_FREE(ptr);
}
- gss_delete_sec_context(&min_stat,&ctx, &output_token);
- ctx = GSS_C_NO_CONTEXT;
}
return SSH_OK;
@@ -713,14 +669,32 @@ int ssh_gssapi_auth_mic(ssh_session session){
ssh_string *oids;
int rc;
int n_oids = 0;
+ OM_uint32 maj_stat, min_stat;
+ char name_buf[256];
+ gss_buffer_desc hostname;
if (ssh_gssapi_init(session) == SSH_ERROR)
return SSH_AUTH_ERROR;
+ /* import target host name */
+ snprintf(name_buf, sizeof(name_buf), "host@%s", session->opts.host);
+ hostname.value = name_buf;
+ hostname.length = strlen(name_buf) + 1;
+ maj_stat = gss_import_name(&min_stat, &hostname,
+ (gss_OID)GSS_C_NT_HOSTBASED_SERVICE,
+ &session->gssapi->client.server_name);
+ if (maj_stat != GSS_S_COMPLETE) {
+ SSH_LOG(0, "importing name %d, %d", maj_stat, min_stat);
+ ssh_gssapi_log_error(0, "importing name", maj_stat);
+ return SSH_PACKET_USED;
+ }
+
+ /* copy username */
+ session->gssapi->user = strdup(session->opts.username);
SSH_LOG(SSH_LOG_PROTOCOL, "Authenticating with gssapi to host %s with user %s",
- session->opts.host, session->opts.username);
- rc = ssh_gssapi_match(session,session->opts.host, session->opts.username, &selected, 0);
+ session->opts.host, session->gssapi->user);
+ rc = ssh_gssapi_match(session, &selected);
if (rc == SSH_ERROR)
return SSH_AUTH_DENIED;
@@ -769,15 +743,11 @@ static gss_OID ssh_gssapi_oid_from_string(ssh_string oid_s){
SSH_PACKET_CALLBACK(ssh_packet_userauth_gssapi_response){
ssh_string oid_s;
- gss_OID oid;
gss_uint32 maj_stat, min_stat;
- int deleg = 0;
gss_buffer_desc input_token = GSS_C_EMPTY_BUFFER;
gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER;
- gss_OID_set tmp;
char *hexa;
ssh_string token;
- gss_cred_id_t creds = GSS_C_NO_CREDENTIAL;
(void)type;
(void)user;
@@ -791,31 +761,24 @@ SSH_PACKET_CALLBACK(ssh_packet_userauth_gssapi_response){
ssh_set_error(session, SSH_FATAL, "Missing OID");
return SSH_PACKET_USED;
}
- oid = ssh_gssapi_oid_from_string(oid_s);
+ session->gssapi->client.oid = ssh_gssapi_oid_from_string(oid_s);
ssh_string_free(oid_s);
- if (!oid) {
+ if (!session->gssapi->client.oid) {
ssh_set_error(session, SSH_FATAL, "Invalid OID");
return SSH_PACKET_USED;
}
- if (session->gssapi->client.client_deleg_creds != GSS_C_NO_CREDENTIAL)
- creds = session->gssapi->client.client_deleg_creds;
- if (creds == GSS_C_NO_CREDENTIAL){
- gss_create_empty_oid_set(&min_stat, &tmp);
- gss_add_oid_set_member(&min_stat, oid, &tmp);
- maj_stat = gss_acquire_cred(&min_stat, session->gssapi->client_name, 0,
- tmp, GSS_C_INITIATE,
- &session->gssapi->client_creds, NULL, NULL);
- gss_release_oid_set(&min_stat, &tmp);
- if (GSS_ERROR(maj_stat)){
- ssh_gssapi_log_error(SSH_LOG_WARNING,"Error acquiring credentials",maj_stat);
- return SSH_PACKET_USED;
- }
- }
+
+ session->gssapi->client.flags = GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG;
+
/* prepare the first TOKEN response */
maj_stat = gss_init_sec_context(&min_stat,
- creds, &session->gssapi->ctx, session->gssapi->client.server_name, oid,
- GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG | (deleg ? GSS_C_DELEG_FLAG : 0),
- 0, NULL, &input_token, NULL, &output_token, NULL, NULL);
+ session->gssapi->client_creds,
+ &session->gssapi->ctx,
+ session->gssapi->client.server_name,
+ session->gssapi->client.oid,
+ session->gssapi->client.flags,
+ 0, NULL, &input_token, NULL,
+ &output_token, NULL, NULL);
if(GSS_ERROR(maj_stat)){
ssh_gssapi_log_error(SSH_LOG_WARNING, "Initializing gssapi context", maj_stat);
return SSH_PACKET_USED;
@@ -832,7 +795,6 @@ SSH_PACKET_CALLBACK(ssh_packet_userauth_gssapi_response){
ssh_string_free(token);
session->auth_state = SSH_AUTH_STATE_GSSAPI_TOKEN;
}
- session->gssapi->client.oid = oid;
return SSH_PACKET_USED;
}
@@ -889,8 +851,6 @@ SSH_PACKET_CALLBACK(ssh_packet_userauth_gssapi_token_client){
char *hexa;
OM_uint32 maj_stat, min_stat;
gss_buffer_desc input_token, output_token = GSS_C_EMPTY_BUFFER;
- gss_cred_id_t creds = GSS_C_NO_CREDENTIAL;
- int deleg = 0;
(void)user;
(void)type;
@@ -910,14 +870,14 @@ SSH_PACKET_CALLBACK(ssh_packet_userauth_gssapi_token_client){
SAFE_FREE(hexa);
input_token.length = ssh_string_len(token);
input_token.value = ssh_string_data(token);
- if (session->gssapi->client.client_deleg_creds != GSS_C_NO_CREDENTIAL)
- creds = session->gssapi->client.client_deleg_creds;
- else
- creds = session->gssapi->client_creds;
maj_stat = gss_init_sec_context(&min_stat,
- creds, &session->gssapi->ctx, session->gssapi->client.server_name, session->gssapi->client.oid,
- GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG | (deleg ? GSS_C_DELEG_FLAG : 0),
- 0, NULL, &input_token, NULL, &output_token, NULL, NULL);
+ session->gssapi->client_creds,
+ &session->gssapi->ctx,
+ session->gssapi->client.server_name,
+ session->gssapi->client.oid,
+ session->gssapi->client.flags,
+ 0, NULL, &input_token, NULL,
+ &output_token, NULL, NULL);
ssh_gssapi_log_error(0, "accepting token", maj_stat);
ssh_string_free(token);