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authorAndrew Bartlett <abartlet@samba.org>2010-12-04 13:48:37 +1100
committerAndrew Bartlett <abartlet@samba.org>2010-12-10 16:08:30 +1100
commitbb7806283e71f3b8029aae0eed326b5847a36d83 (patch)
tree75ae29746351bd1aaf09d54c4779b5584f1eb98a
parent10441ed83d701d6db64c3a933cf09957355e1db2 (diff)
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s3-libads Default to NOT using the server-supplied principal from SPNEGO
This principal is not supplied by later versions of windows, and using it opens up some oportunities for man in the middle attacks. (Becuase it isn't the name being contacted that is verified with the KDC). This adds the option 'client use spnego principal' to the smb.conf (as used in Samba4) to control this behaivour. As in Samba4, this defaults to false. Against 2008 servers, this will not change behaviour. Against earlier servers, it may cause a downgrade to NTLMSSP more often, in environments where server names are not registered with the KDC as servicePrincipalName values. Andrew Bartlett
-rw-r--r--source3/include/proto.h1
-rw-r--r--source3/libads/sasl.c8
-rw-r--r--source3/libsmb/cliconnect.c5
-rw-r--r--source3/param/loadparm.c11
4 files changed, 19 insertions, 6 deletions
diff --git a/source3/include/proto.h b/source3/include/proto.h
index 19c693b252..94196b41d1 100644
--- a/source3/include/proto.h
+++ b/source3/include/proto.h
@@ -3306,6 +3306,7 @@ bool lp_use_mmap(void);
bool lp_unix_extensions(void);
bool lp_use_spnego(void);
bool lp_client_use_spnego(void);
+bool lp_client_use_spnego_principal(void);
bool lp_hostname_lookups(void);
bool lp_change_notify(const struct share_params *p );
bool lp_kernel_change_notify(const struct share_params *p );
diff --git a/source3/libads/sasl.c b/source3/libads/sasl.c
index 653d546ccd..2ba347486a 100644
--- a/source3/libads/sasl.c
+++ b/source3/libads/sasl.c
@@ -664,10 +664,12 @@ static ADS_STATUS ads_generate_service_principal(ADS_STRUCT *ads,
the principal name back in the first round of
the SASL bind reply. So we guess based on server
name and realm. --jerry */
- /* Also try best guess when we get the w2k8 ignore
- principal back - gd */
+ /* Also try best guess when we get the w2k8 ignore principal
+ back, or when we are configured to ignore it - gd,
+ abartlet */
- if (!given_principal ||
+ if (!lp_client_use_spnego_principal() ||
+ !given_principal ||
strequal(given_principal, ADS_IGNORE_PRINCIPAL)) {
status = ads_guess_service_principal(ads, &p->string);
diff --git a/source3/libsmb/cliconnect.c b/source3/libsmb/cliconnect.c
index 1e11e158f7..c66314891d 100644
--- a/source3/libsmb/cliconnect.c
+++ b/source3/libsmb/cliconnect.c
@@ -1279,10 +1279,9 @@ ADS_STATUS cli_session_setup_spnego(struct cli_state *cli, const char *user,
}
}
- /* If we get a bad principal, try to guess it if
- we have a valid host NetBIOS name.
+ /* We may not be allowed to use the server-supplied SPNEGO principal, or it may not have been supplied to us
*/
- if (strequal(principal, ADS_IGNORE_PRINCIPAL)) {
+ if (!lp_client_use_spnego_principal() || strequal(principal, ADS_IGNORE_PRINCIPAL)) {
TALLOC_FREE(principal);
}
diff --git a/source3/param/loadparm.c b/source3/param/loadparm.c
index 0bc27dca03..05958b47d2 100644
--- a/source3/param/loadparm.c
+++ b/source3/param/loadparm.c
@@ -338,6 +338,7 @@ struct global {
bool bClientNTLMv2Auth;
bool bClientPlaintextAuth;
bool bClientUseSpnego;
+ bool client_use_spnego_principal;
bool bDebugPrefixTimestamp;
bool bDebugHiresTimestamp;
bool bDebugPid;
@@ -1399,6 +1400,15 @@ static struct parm_struct parm_table[] = {
.flags = FLAG_ADVANCED,
},
{
+ .label = "client use spnego principal",
+ .type = P_BOOL,
+ .p_class = P_GLOBAL,
+ .ptr = &Globals.client_use_spnego_principal,
+ .special = NULL,
+ .enum_list = NULL,
+ .flags = FLAG_ADVANCED,
+ },
+ {
.label = "username",
.type = P_STRING,
.p_class = P_LOCAL,
@@ -5711,6 +5721,7 @@ FN_GLOBAL_BOOL(lp_use_mmap, &Globals.bUseMmap)
FN_GLOBAL_BOOL(lp_unix_extensions, &Globals.bUnixExtensions)
FN_GLOBAL_BOOL(lp_use_spnego, &Globals.bUseSpnego)
FN_GLOBAL_BOOL(lp_client_use_spnego, &Globals.bClientUseSpnego)
+FN_GLOBAL_BOOL(lp_client_use_spnego_principal, &Globals.client_use_spnego_principal)
FN_GLOBAL_BOOL(lp_hostname_lookups, &Globals.bHostnameLookups)
FN_LOCAL_PARM_BOOL(lp_change_notify, bChangeNotify)
FN_LOCAL_PARM_BOOL(lp_kernel_change_notify, bKernelChangeNotify)