From d68424b5ef92f5810760f90e9eeb664572a61e4e Mon Sep 17 00:00:00 2001 From: Stefan Metzmacher Date: Tue, 15 Dec 2015 14:49:36 +0100 Subject: [PATCH 01/10] CVE-2016-2118: s3: rpcclient: change the default auth level from DCERPC_AUTH_LEVEL_CONNECT to DCERPC_AUTH_LEVEL_INTEGRITY ncacn_ip_tcp:server should get the same protection as ncacn_np:server if authentication and smb signing is used. BUG: https://bugzilla.samba.org/show_bug.cgi?id=11616 Signed-off-by: Stefan Metzmacher (cherry picked from commit dab41dee8a4fb27dbf3913b0e44a4cc726e3ac98) --- source3/rpcclient/rpcclient.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) --- source3/rpcclient/rpcclient.c +++ source3/rpcclient/rpcclient.c @@ -1062,10 +1062,9 @@ out_free: } } if (pipe_default_auth_type != DCERPC_AUTH_TYPE_NONE) { - /* If neither Integrity or Privacy are requested then - * Use just Connect level */ + /* If nothing is requested then default to integrity */ if (pipe_default_auth_level == DCERPC_AUTH_LEVEL_NONE) { - pipe_default_auth_level = DCERPC_AUTH_LEVEL_CONNECT; + pipe_default_auth_level = DCERPC_AUTH_LEVEL_INTEGRITY; } } --- source4/librpc/rpc/dcerpc_util.c +++ source4/librpc/rpc/dcerpc_util.c @@ -593,15 +593,15 @@ struct composite_context *dcerpc_pipe_au /* Perform an authenticated DCE-RPC bind */ - if (!(conn->flags & (DCERPC_SIGN|DCERPC_SEAL))) { + if (!(conn->flags & (DCERPC_CONNECT|DCERPC_SEAL))) { /* we are doing an authenticated connection, - but not using sign or seal. We must force - the CONNECT dcerpc auth type as a NONE auth - type doesn't allow authentication - information to be passed. + which needs to use [connect], [sign] or [seal]. + If nothing is specified, we default to [sign] now. + This give roughly the same protection as + ncacn_np with smb signing. */ - conn->flags |= DCERPC_CONNECT; + conn->flags |= DCERPC_SIGN; } if (s->binding->flags & DCERPC_AUTH_SPNEGO) { --- /dev/null +++ docs-xml/smbdotconf/security/allowdcerpcauthlevelconnect.xml @@ -0,0 +1,22 @@ + + + This option controls whether DCERPC services are allowed to + be used with DCERPC_AUTH_LEVEL_CONNECT, which provides authentication, + but no per message integrity nor privacy protection. + + The behavior can be controlled per interface name (e.g. lsarpc, netlogon, samr, srvsvc, + winreg, wkssvc ...) by using 'allow dcerpc auth level connect:interface = no' as option. + + This option yields precedence to the implentation specific restrictions. + E.g. the drsuapi and backupkey protocols require DCERPC_AUTH_LEVEL_PRIVACY. + While others like samr and lsarpc have a hardcoded default of no. + + + +no +yes + + --- source3/include/proto.h +++ source3/include/proto.h @@ -1821,6 +1821,7 @@ char* lp_perfcount_module(void); void lp_set_passdb_backend(const char *backend); void widelinks_warning(int snum); char *lp_ncalrpc_dir(void); +bool lp_allow_dcerpc_auth_level_connect(void); /* The following definitions come from param/loadparm_server_role.c */ --- source3/param/loadparm.c +++ source3/param/loadparm.c @@ -355,6 +355,7 @@ struct global { bool bUseMmap; bool bHostnameLookups; bool bUnixExtensions; + bool bAllowDcerpcAuthLevelConnect; bool bDisableNetbios; char * szDedicatedKeytabFile; int iKerberosMethod; @@ -2303,6 +2304,15 @@ static struct parm_struct parm_table[] = .flags = FLAG_ADVANCED, }, { + .label = "allow dcerpc auth level connect", + .type = P_BOOL, + .p_class = P_GLOBAL, + .ptr = &Globals.bAllowDcerpcAuthLevelConnect, + .special = NULL, + .enum_list = NULL, + .flags = FLAG_ADVANCED, + }, + { .label = "use spnego", .type = P_BOOL, .p_class = P_GLOBAL, @@ -5371,6 +5381,8 @@ static void init_globals(bool reinit_glo Globals.bClientNTLMv2Auth = True; /* Client should always use use NTLMv2, as we can't tell that the server supports it, but most modern servers do */ /* Note, that we will also use NTLM2 session security (which is different), if it is available */ + Globals.bAllowDcerpcAuthLevelConnect = false; /* we don't allow this by default */ + Globals.map_to_guest = 0; /* By Default, "Never" */ Globals.oplock_break_wait_time = 0; /* By Default, 0 msecs. */ Globals.enhanced_browsing = true; @@ -5745,6 +5757,7 @@ FN_GLOBAL_INTEGER(lp_username_map_cache_ FN_GLOBAL_STRING(lp_check_password_script, &Globals.szCheckPasswordScript) +FN_GLOBAL_BOOL(lp_allow_dcerpc_auth_level_connect, &Globals.bAllowDcerpcAuthLevelConnect) FN_GLOBAL_STRING(lp_wins_hook, &Globals.szWINSHook) FN_GLOBAL_CONST_STRING(lp_template_homedir, &Globals.szTemplateHomedir) FN_GLOBAL_CONST_STRING(lp_template_shell, &Globals.szTemplateShell) --- source3/include/ntdomain.h +++ source3/include/ntdomain.h @@ -89,6 +89,10 @@ typedef struct pipe_rpc_fns { uint32 context_id; struct ndr_syntax_id syntax; + /* + * shall we allow "connect" auth level for this interface ? + */ + bool allow_connect; } PIPE_RPC_FNS; /* --- source3/rpc_server/srv_pipe.c +++ source3/rpc_server/srv_pipe.c @@ -44,6 +44,11 @@ #include "rpc_server/srv_pipe.h" #include "../librpc/gen_ndr/ndr_dcerpc.h" #include "../librpc/ndr/ndr_dcerpc.h" +#include "../librpc/gen_ndr/ndr_samr.h" +#include "../librpc/gen_ndr/ndr_lsa.h" +#include "../librpc/gen_ndr/ndr_netlogon.h" +#include "../librpc/gen_ndr/ndr_epmapper.h" +#include "../librpc/gen_ndr/ndr_echo.h" #undef DBGC_CLASS #define DBGC_CLASS DBGC_RPC_SRV @@ -340,6 +345,8 @@ static bool check_bind_req(struct pipes_ uint32 context_id) { struct pipe_rpc_fns *context_fns; + const char *interface_name = NULL; + bool ok; DEBUG(3,("check_bind_req for %s\n", get_pipe_name_from_syntax(talloc_tos(), abstract))); @@ -390,12 +397,57 @@ static bool check_bind_req(struct pipes_ return False; } + interface_name = get_pipe_name_from_syntax(talloc_tos(), + abstract); + + SMB_ASSERT(interface_name != NULL); + context_fns->next = context_fns->prev = NULL; context_fns->n_cmds = rpc_srv_get_pipe_num_cmds(abstract); context_fns->cmds = rpc_srv_get_pipe_cmds(abstract); context_fns->context_id = context_id; context_fns->syntax = *abstract; + context_fns->allow_connect = lp_allow_dcerpc_auth_level_connect(); + /* + * for the samr and the lsarpc interfaces we don't allow "connect" + * auth_level by default. + */ + ok = ndr_syntax_id_equal(abstract, &ndr_table_samr.syntax_id); + if (ok) { + context_fns->allow_connect = false; + } + ok = ndr_syntax_id_equal(abstract, &ndr_table_lsarpc.syntax_id); + if (ok) { + context_fns->allow_connect = false; + } + ok = ndr_syntax_id_equal(abstract, &ndr_table_netlogon.syntax_id); + if (ok) { + context_fns->allow_connect = false; + } + /* + * for the epmapper and echo interfaces we allow "connect" + * auth_level by default. + */ + ok = ndr_syntax_id_equal(abstract, &ndr_table_epmapper.syntax_id); + if (ok) { + context_fns->allow_connect = true; + } + ok = ndr_syntax_id_equal(abstract, &ndr_table_rpcecho.syntax_id); + if (ok) { + context_fns->allow_connect = true; + } + /* + * every interface can be modified to allow "connect" auth_level by + * using a parametric option like: + * allow dcerpc auth level connect: + * e.g. + * allow dcerpc auth level connect:samr = yes + */ + context_fns->allow_connect = lp_parm_bool(-1, + "allow dcerpc auth level connect", + interface_name, context_fns->allow_connect); + /* add to the list of open contexts */ DLIST_ADD( p->contexts, context_fns ); @@ -1736,6 +1788,7 @@ static bool api_pipe_request(struct pipe TALLOC_CTX *frame = talloc_stackframe(); bool ret = False; PIPE_RPC_FNS *pipe_fns; + const char *interface_name = NULL; if (!p->pipe_bound) { DEBUG(1, ("Pipe not bound!\n")); @@ -1757,8 +1810,36 @@ static bool api_pipe_request(struct pipe return false; } + interface_name = get_pipe_name_from_syntax(talloc_tos(), + &pipe_fns->syntax); + + SMB_ASSERT(interface_name != NULL); + DEBUG(5, ("Requested \\PIPE\\%s\n", - get_pipe_name_from_syntax(talloc_tos(), &pipe_fns->syntax))); + interface_name)); + + switch (p->auth.auth_level) { + case DCERPC_AUTH_LEVEL_NONE: + case DCERPC_AUTH_LEVEL_INTEGRITY: + case DCERPC_AUTH_LEVEL_PRIVACY: + break; + default: + if (!pipe_fns->allow_connect) { + DEBUG(1, ("%s: restrict auth_level_connect access " + "to [%s] with auth[type=0x%x,level=0x%x] " + "on [%s] from [%s]\n", + __func__, interface_name, + p->auth.auth_type, + p->auth.auth_level, + derpc_transport_string_by_transport(p->transport), + p->client_id->name)); + + setup_fault_pdu(p, NT_STATUS(DCERPC_FAULT_ACCESS_DENIED)); + TALLOC_FREE(frame); + return true; + } + break; + } if (!srv_pipe_check_verification_trailer(p, pkt, pipe_fns)) { DEBUG(1, ("srv_pipe_check_verification_trailer: failed\n")); --- source3/selftest/knownfail +++ source3/selftest/knownfail @@ -18,3 +18,5 @@ samba3.posix_s3.nbt.dgram.*netlogon2 samba3.*rap.sam.*.useradd # Not provided by Samba 3 samba3.*rap.sam.*.userdelete # Not provided by Samba 3 samba3.*rap.basic.*.netsessiongetinfo # Not provided by Samba 3 +samba3.blackbox.rpcclient.over.ncacn_np.with.*connect.* # we don't allow auth_level_connect anymore +samba3.posix_s3.rpc.lsa.lookupsids.*ncacn_ip_tcp.*connect.* # we don't allow auth_level_connect anymore --- source3/selftest/tests.py +++ source3/selftest/tests.py @@ -201,6 +201,8 @@ if sub.returncode == 0: plansmbtorturetestsuite(t, "s3dc", '//$SERVER_IP/tmpguest -U$USERNAME%$PASSWORD') elif t == "raw.samba3posixtimedlock": plansmbtorturetestsuite(t, "s3dc", '//$SERVER_IP/tmpguest -U$USERNAME%$PASSWORD --option=torture:localdir=$SELFTEST_PREFIX/dc/share') + elif t == "rpc.samr.passwords.validate": + plansmbtorturetestsuite(t, "s3dc", 'ncacn_np:$SERVER_IP[seal] -U$USERNAME%$PASSWORD', 'over ncacn_np ') else: plansmbtorturetestsuite(t, "s3dc", '//$SERVER_IP/tmp -U$USERNAME%$PASSWORD') --- source3/rpc_server/samr/srv_samr_nt.c +++ source3/rpc_server/samr/srv_samr_nt.c @@ -6628,6 +6628,11 @@ NTSTATUS _samr_ValidatePassword(struct p struct samr_GetDomPwInfo pw; struct samr_PwInfo dom_pw_info; + if (p->auth.auth_level != DCERPC_AUTH_LEVEL_PRIVACY) { + p->fault_state = DCERPC_FAULT_ACCESS_DENIED; + return NT_STATUS_ACCESS_DENIED; + } + if (r->in.level < 1 || r->in.level > 3) { return NT_STATUS_INVALID_INFO_CLASS; }