fixed a problem with getgroups() where it could include our current

effective gid which could mean that the user gets group 0 in their
group list for acl interpretation

this is a replacement fix for the one richard did in 2.2 (which didn't
cope wiith variable behaviour depending on which nss module was in
use)
(This used to be commit cfc5ca3416cea5ea5d2ac34f5521cb6367e42cd2)

2 files changed, 28 insertions, 13 deletions

diff --git a/source3/smbd/password.c b/source3/smbd/password.c
index f9bcad4154..82c0cef77d 100644
--- a/source3/smbd/password.c
+++ b/source3/smbd/password.c
@@ -289,7 +289,7 @@ int register_vuid(auth_serversupplied_info *server_info, char *smb_name)
 	/* Find all the groups this uid is in and store them. 
 		Used by change_to_user() */
 	initialise_groups(vuser->user.unix_name, vuser->uid, vuser->gid);
-	get_current_groups( &vuser->n_groups, &vuser->groups);
+	get_current_groups(vuser->gid, &vuser->n_groups, &vuser->groups);
 
 	if (server_info->ptok)
 		add_supplementary_nt_login_groups(&vuser->n_groups, &vuser->groups, &server_info->ptok);
diff --git a/source3/smbd/sec_ctx.c b/source3/smbd/sec_ctx.c
index 87bf8b1744..bdcdce6e14 100644
--- a/source3/smbd/sec_ctx.c
+++ b/source3/smbd/sec_ctx.c
@@ -132,29 +132,39 @@ static void gain_root(void)
  Get the list of current groups.
 ****************************************************************************/
 
-int get_current_groups(int *p_ngroups, gid_t **p_groups)
+int get_current_groups(gid_t gid, int *p_ngroups, gid_t **p_groups)
 {
 	int i;
 	gid_t grp;
-	int ngroups = sys_getgroups(0,&grp);
-	gid_t *groups;
+	int ngroups;
+	gid_t *groups = NULL;
 
 	(*p_ngroups) = 0;
 	(*p_groups) = NULL;
 
-	if (ngroups <= 0)
-		return -1;
+	/* this looks a little strange, but is needed to cope with
+	   systems that put the current egid in the group list
+	   returned from getgroups() (tridge) */
+	save_re_gid();
+	set_effective_gid(gid);
+	setgid(gid);
 
-	if((groups = (gid_t *)malloc(sizeof(gid_t)*ngroups)) == NULL) {
+	ngroups = sys_getgroups(0,&grp);
+	if (ngroups <= 0) {
+		goto fail;
+	}
+
+	if((groups = (gid_t *)malloc(sizeof(gid_t)*(ngroups+1))) == NULL) {
 		DEBUG(0,("setup_groups malloc fail !\n"));
-		return -1;
+		goto fail;
 	}
 
 	if ((ngroups = sys_getgroups(ngroups,groups)) == -1) {
-		SAFE_FREE(groups);
-		return -1;
+		goto fail;
 	}
 
+	restore_re_gid();
+
 	(*p_ngroups) = ngroups;
 	(*p_groups) = groups;
 
@@ -164,7 +174,12 @@ int get_current_groups(int *p_ngroups, gid_t **p_groups)
 	}
 	DEBUG( 3, ( "\n" ) );
 
-    return ngroups;
+	return ngroups;
+
+fail:
+	SAFE_FREE(groups);
+	restore_re_gid();
+	return -1;
 }
 
 /****************************************************************************
@@ -204,7 +219,7 @@ BOOL initialise_groups(char *user, uid_t uid, gid_t gid)
 	SAFE_FREE(prev_ctx_p->groups);
 	prev_ctx_p->ngroups = 0;
 
-	get_current_groups(&prev_ctx_p->ngroups, &prev_ctx_p->groups);
+	get_current_groups(gid, &prev_ctx_p->ngroups, &prev_ctx_p->groups);
 
  done:
 	unbecome_root();
@@ -404,7 +419,7 @@ void init_sec_ctx(void)
 	ctx_p->uid = geteuid();
 	ctx_p->gid = getegid();
 
-	get_current_groups(&ctx_p->ngroups, &ctx_p->groups);
+	get_current_groups(ctx_p->gid, &ctx_p->ngroups, &ctx_p->groups);
 
 	ctx_p->token = NULL; /* Maps to guest user. */