implemented getgrouplist() for systems that don't have it and use it

in get_alias_user_groups(). The old method used getgrent() which is
extremely slow when the number of groups is large
(This used to be commit 44e92b6523ca2c119c2562df22eb71138dca9d9d)

4 files changed, 131 insertions, 55 deletions

diff --git a/source3/configure.in b/source3/configure.in
index 77c14c7191..4397d5846c 100644
--- a/source3/configure.in
+++ b/source3/configure.in
@@ -746,7 +746,7 @@ AC_CHECK_FUNCS(setpriv setgidx setuidx setgroups sysconf mktime rename ftruncate
 AC_CHECK_FUNCS(lstat64 fopen64 atexit grantpt dup2 lseek64 ftruncate64 readdir64)
 AC_CHECK_FUNCS(fseek64 fseeko64 ftell64 ftello64 setluid getpwanam setlinebuf)
 AC_CHECK_FUNCS(srandom random srand rand setenv usleep strcasecmp fcvt fcvtl symlink readlink)
-AC_CHECK_FUNCS(syslog vsyslog)
+AC_CHECK_FUNCS(syslog vsyslog getgrouplist)
 # setbuffer is needed for smbtorture
 AC_CHECK_FUNCS(setbuffer)
 
diff --git a/source3/lib/replace.c b/source3/lib/replace.c
index 2cc7d48adb..e2664accfa 100644
--- a/source3/lib/replace.c
+++ b/source3/lib/replace.c
@@ -428,3 +428,69 @@ char *rep_inet_ntoa(struct in_addr ip)
 }
 #endif /* HAVE_SYSLOG */
 #endif /* HAVE_VSYSLOG */
+
+
+#ifndef HAVE_GETGROUPLIST
+/*
+  This is a *much* faster way of getting the list of groups for a user
+  without changing the current supplemenrary group list. The old
+  method used getgrent() which could take 20 minutes on a really big
+  network with hundeds of thousands of groups and users. The new method
+  takes a couple of seconds.
+
+  NOTE!! this function only works if it is called as root!
+  */
+ int getgrouplist(const char *user, gid_t gid, gid_t *groups, int *grpcnt)
+{
+	gid_t *gids_saved;
+	int ret, ngrp_saved;
+
+	/* work out how many groups we need to save */
+	ngrp_saved = getgroups(0, NULL);
+	if (ngrp_saved == -1) {
+		/* this shouldn't happen */
+		return -1;
+	}
+	
+	gids_saved = (gid_t *)malloc(sizeof(gid_t) * (ngrp_saved+1));
+	if (!gids_saved) {
+		errno = ENOMEM;
+		return -1;
+	}
+
+	ngrp_saved = getgroups(ngrp_saved, gids_saved);
+	if (ngrp_saved == -1) {
+		free(gids_saved);
+		/* very strange! */
+		return -1;
+	}
+
+	if (initgroups(user, gid) != 0) {
+		free(gids_saved);
+		return -1;
+	}
+
+	/* this must be done to cope with systems that put the current egid in the
+	   return from getgroups() */
+	save_re_gid();
+	set_effective_gid(gid);
+	setgid(gid);
+
+	ret = getgroups(*grpcnt, groups);
+	if (ret >= 0) {
+		*grpcnt = ret;
+	}
+
+	restore_re_gid();
+
+	if (setgroups(ngrp_saved, gids_saved) != 0) {
+		/* yikes! */
+		DEBUG(0,("ERROR: getgrouplist: failed to reset group list!\n"));
+		free(gids_saved);
+		return -1;
+	}
+
+	free(gids_saved);
+	return ret;
+}
+#endif
diff --git a/source3/lib/util_getent.c b/source3/lib/util_getent.c
index 2e76121aae..5d2fcd7652 100644
--- a/source3/lib/util_getent.c
+++ b/source3/lib/util_getent.c
@@ -21,27 +21,6 @@
 
 #include "includes.h"
 
-#if 0
-static void print_grent_list(struct sys_grent *glist)
-{
-	DEBUG(100, ("print_grent_list: %x\n", glist ));
-	while (glist) {
-		DEBUG(100,("glist: %x ", glist));
-		if (glist->gr_name)
-			DEBUG(100,(": gr_name = (%x) %s ", glist->gr_name, glist->gr_name));
-		if (glist->gr_passwd)
-			DEBUG(100,(": gr_passwd = (%x) %s ", glist->gr_passwd, glist->gr_passwd));
-		if (glist->gr_mem) {
-			int i;
-			for (i = 0; glist->gr_mem[i]; i++)
-				DEBUG(100,(" : gr_mem[%d] = (%x) %s ", i, glist->gr_mem[i], glist->gr_mem[i]));
-		}
-		DEBUG(100,(": gr_next = %x\n", glist->next ));
-		glist = glist->next;
-	}
-	DEBUG(100,("FINISHED !\n\n"));
-}
-#endif
 
 /****************************************************************
  Returns a single linked list of group entries.
@@ -320,3 +299,38 @@ void free_userlist(struct sys_userlist *list_head)
 		SAFE_FREE(old_head);
 	}
 }
+
+
+/*
+  return a full list of groups for a user
+
+  returns the number of groups the user is a member of. The return will include the
+  users primary group.
+
+  remember to free the resulting gid_t array
+
+  NOTE! you must be root to call this function on some systems
+*/
+int getgroups_user(const char *user, gid_t **groups)
+{
+	struct passwd *pwd;
+	int ngrp, max_grp;
+
+	pwd = getpwnam(user);
+	if (!pwd) return -1;
+
+	max_grp = groups_max();
+	(*groups) = (gid_t *)malloc(sizeof(gid_t) * max_grp);
+	if (! *groups) {
+		errno = ENOMEM;
+		return -1;
+	}
+
+	ngrp = getgrouplist(user, pwd->pw_gid, *groups, &max_grp);
+	if (ngrp <= 0) {
+		free(*groups);
+		return ngrp;
+	}
+
+	return ngrp;
+}
diff --git a/source3/rpc_server/srv_util.c b/source3/rpc_server/srv_util.c
index f896d1d9d8..50bf5db4fd 100644
--- a/source3/rpc_server/srv_util.c
+++ b/source3/rpc_server/srv_util.c
@@ -84,10 +84,10 @@ rid_name domain_group_rids[] =
 NTSTATUS get_alias_user_groups(TALLOC_CTX *ctx, DOM_SID *sid, int *numgroups, uint32 **prids, DOM_SID *q_sid)
 {
 	SAM_ACCOUNT *sam_pass=NULL;
-	struct sys_grent *glist;
-	struct sys_grent *grp;
-	int i, num, cur_rid=0;
+	int i, cur_rid=0;
 	gid_t gid;
+	gid_t *groups = NULL;
+	int num_groups;
 	GROUP_MAP map;
 	DOM_SID tmp_sid;
 	fstring user_name;
@@ -130,16 +130,21 @@ NTSTATUS get_alias_user_groups(TALLOC_CTX *ctx, DOM_SID *sid, int *numgroups, ui
 	fstrcpy(user_name, pdb_get_username(sam_pass));
 	grid=pdb_get_group_rid(sam_pass);
 	gid=pdb_get_gid(sam_pass);
-	
-	grp = glist = getgrent_list();
-	if (grp == NULL) {
+
+	become_root();
+	/* on some systems this must run as root */
+	num_groups = getgroups_user(user_name, &groups);	
+	unbecome_root();
+	if (num_groups == -1) {
+		/* this should never happen */
+		DEBUG(2,("get_alias_user_groups: getgroups_user failed\n"));
 		pdb_free_sam(&sam_pass);
-		return NT_STATUS_NO_MEMORY;
+		return NT_STATUS_UNSUCCESSFUL;
 	}
-	
-	for (; grp != NULL; grp = grp->next) {
-		if(!get_group_from_gid(grp->gr_gid, &map, MAPPING_WITHOUT_PRIV)) {
-			DEBUG(10,("get_alias_user_groups: gid %d. not found\n", (int)grp->gr_gid));
+
+	for (i=0;i<num_groups;i++) {
+		if(!get_group_from_gid(groups[i], &map, MAPPING_WITHOUT_PRIV)) {
+			DEBUG(10,("get_alias_user_groups: gid %d. not found\n", (int)groups[i]));
 			continue;
 		}
 		
@@ -159,7 +164,7 @@ NTSTATUS get_alias_user_groups(TALLOC_CTX *ctx, DOM_SID *sid, int *numgroups, ui
 		}
 
 		/* Don't return winbind groups as they are not local! */
-		if (winbind_groups_exist && (grp->gr_gid >= winbind_gid_low) && (grp->gr_gid <= winbind_gid_high)) {
+		if (winbind_groups_exist && (groups[i] >= winbind_gid_low) && (groups[i] <= winbind_gid_high)) {
 			DEBUG(10,("get_alias_user_groups: not returing %s, not local.\n", map.nt_name));
 			continue;
 		}
@@ -170,30 +175,21 @@ NTSTATUS get_alias_user_groups(TALLOC_CTX *ctx, DOM_SID *sid, int *numgroups, ui
 			continue;			
 		}
 		
-		/* the group is fine, we can check if there is the user we're looking for */
-		DEBUG(10,("get_alias_user_groups: checking if the user is a member of %s.\n", map.nt_name));
-		
-		for(num=0; grp->gr_mem[num]!=NULL; num++) {
-			if(strcmp(grp->gr_mem[num], user_name)==0) {
-				/* we found the user, add the group to the list */
-				
-				new_rids=(uint32 *)Realloc(rids, sizeof(uint32)*(cur_rid+1));
-				if (new_rids==NULL) {
-					DEBUG(10,("get_alias_user_groups: could not realloc memory\n"));
-					pdb_free_sam(&sam_pass);
-					return NT_STATUS_NO_MEMORY;
-				}
-				rids=new_rids;
-				
-				sid_peek_rid(&map.sid, &(rids[cur_rid]));
-				DEBUG(10,("get_alias_user_groups: user found in group %s\n", map.nt_name));
-				cur_rid++;
-				break;
-			}
+		new_rids=(uint32 *)Realloc(rids, sizeof(uint32)*(cur_rid+1));
+		if (new_rids==NULL) {
+			DEBUG(10,("get_alias_user_groups: could not realloc memory\n"));
+			pdb_free_sam(&sam_pass);
+			free(groups);
+			return NT_STATUS_NO_MEMORY;
 		}
+		rids=new_rids;
+		
+		sid_peek_rid(&map.sid, &(rids[cur_rid]));
+		cur_rid++;
+		break;
 	}
 
-	grent_free(glist);
+	free(groups);
 
 	/* now check for the user's gid (the primary group rid) */
 	for (i=0; i<cur_rid && grid!=rids[i]; i++)