1 files changed, 295 insertions, 0 deletions
diff --git a/source3/smbd/sec_ctx.c b/source3/smbd/sec_ctx.c
new file mode 100644
index 0000000000..e3aac77d8e
--- /dev/null
+++ b/source3/smbd/sec_ctx.c
@@ -0,0 +1,295 @@
+/* 
+   Unix SMB/Netbios implementation.
+   Version 1.9.
+   uid/user handling
+   Copyright (C) Tim Potter 2000
+   
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+   
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#include "includes.h"
+
+extern int DEBUGLEVEL;
+extern struct current_user current_user;
+
+struct sec_ctx {
+	uid_t uid;
+	uid_t gid;
+	int ngroups;
+	gid_t *groups;
+};
+
+/* A stack of security contexts.  We include the current context as being
+   the first one, so there is room for another MAX_SEC_CTX_DEPTH more. */
+
+static struct sec_ctx sec_ctx_stack[MAX_SEC_CTX_DEPTH + 1];
+static int sec_ctx_stack_ndx;
+
+/* Become the specified uid */
+
+static BOOL become_uid(uid_t uid)
+{
+	/* Check for dodgy uid values */
+
+	if (uid == (uid_t)-1 || 
+	    ((sizeof(uid_t) == 2) && (uid == (uid_t)65535))) {
+		static int done;
+ 
+		if (!done) {
+			DEBUG(1,("WARNING: using uid %d is a security risk\n",
+				 (int)uid));
+			done = 1;
+		}
+	}
+
+	/* Set effective user id */
+
+	set_effective_uid(uid);
+	current_user.uid = uid;
+
+#ifdef WITH_PROFILE
+	profile_p->uid_changes++;
+#endif
+
+	return True;
+}
+
+/* Become the specified gid */
+
+static BOOL become_gid(gid_t gid)
+{
+	/* Check for dodgy gid values */
+
+	if (gid == (gid_t)-1 || ((sizeof(gid_t) == 2) && 
+				 (gid == (gid_t)65535))) {
+		static int done;
+		
+		if (!done) {
+			DEBUG(1,("WARNING: using gid %d is a security risk\n",
+				 (int)gid));  
+			done = 1;
+		}
+	}
+  
+	/* Set effective group id */
+
+	set_effective_gid(gid);
+	current_user.gid = gid;
+	
+	return True;
+}
+
+/* Become the specified uid and gid */
+
+static BOOL become_id(uid_t uid, gid_t gid)
+{
+	return become_gid(gid) && become_uid(uid);
+}
+
+/* Drop back to root privileges in order to change to another user */
+
+static void gain_root(void)
+{
+	if (geteuid() != 0) {
+		set_effective_uid(0);
+
+		if (geteuid() != 0) {
+			DEBUG(0,
+			      ("Warning: You appear to have a trapdoor "
+			       "uid system\n"));
+		}
+	}
+
+	if (getegid() != 0) {
+		set_effective_gid(0);
+
+		if (getegid() != 0) {
+			DEBUG(0,
+			      ("Warning: You appear to have a trapdoor "
+			       "gid system\n"));
+		}
+	}
+}
+
+/* Get the list of current groups */
+
+static void get_current_groups(int *ngroups, gid_t **groups)
+{
+	*ngroups = getgroups(0, NULL);
+	*groups = (gid_t *)malloc(*ngroups * sizeof(gid_t));
+
+	if (!groups) {
+		DEBUG(0, ("Out of memory in get_current_groups\n"));
+		return;
+	}
+
+	getgroups(*ngroups, *groups);
+}
+
+/* Create a new security context on the stack.  It is the same as the old
+   one.  User changes are done using the set_sec_ctx() function. */
+
+BOOL push_sec_ctx(void)
+{
+	/* Check we don't overflow our stack */
+
+	if (sec_ctx_stack_ndx == (MAX_SEC_CTX_DEPTH)) {
+		DEBUG(0, ("Security context stack overflow!\n"));
+		return False;
+	}
+
+	/* Store previous user context */
+
+	sec_ctx_stack_ndx++;
+
+	sec_ctx_stack[sec_ctx_stack_ndx].uid = geteuid();
+	sec_ctx_stack[sec_ctx_stack_ndx].gid = getegid();
+
+	sec_ctx_stack[sec_ctx_stack_ndx].ngroups = sys_getgroups(0, NULL);
+
+	if (!(sec_ctx_stack[sec_ctx_stack_ndx].groups = 
+	      malloc(sec_ctx_stack[sec_ctx_stack_ndx].ngroups * 
+		     sizeof(gid_t)))) {
+		DEBUG(0, ("Out of memory in push_sec_ctx()\n"));
+		return False;
+	}
+
+	sys_getgroups(sec_ctx_stack[sec_ctx_stack_ndx].ngroups,
+		  sec_ctx_stack[sec_ctx_stack_ndx].groups);
+
+	return True;
+}
+
+/* Set the current security context to a given user */
+
+void set_sec_ctx(uid_t uid, gid_t gid, int ngroups, gid_t *groups)
+{
+	/* Set the security context */
+
+	DEBUG(3, ("setting sec ctx (%d, %d)\n", uid, gid));
+
+	gain_root();
+
+#ifdef HAVE_SETGROUPS
+	sys_setgroups(ngroups, groups);
+
+	sec_ctx_stack[sec_ctx_stack_ndx].ngroups = ngroups;
+	sec_ctx_stack[sec_ctx_stack_ndx].groups = 
+		memdup(groups, sizeof(gid_t) * ngroups);
+#endif
+
+	become_id(uid, gid);
+
+	sec_ctx_stack[sec_ctx_stack_ndx].uid = uid;
+	sec_ctx_stack[sec_ctx_stack_ndx].gid = gid;
+
+	/* Update current_user stuff */
+
+	current_user.uid = uid;
+	current_user.gid = gid;
+	current_user.ngroups = ngroups;
+	current_user.groups = groups;
+}
+
+/* Become root context */
+
+void set_root_sec_ctx(void)
+{
+	/* May need to worry about supplementary groups at some stage */
+
+	set_sec_ctx(0, 0, 0, NULL);
+}
+
+/* Pop a security context from the stack */
+
+BOOL pop_sec_ctx(void)
+{
+	/* Check for stack underflow */
+
+	if (sec_ctx_stack_ndx == 0) {
+		DEBUG(0, ("Security context stack underflow!\n"));
+		return False;
+	}
+
+	/* Clear previous user info */
+
+	sec_ctx_stack[sec_ctx_stack_ndx].uid = (uid_t)-1;
+	sec_ctx_stack[sec_ctx_stack_ndx].gid = (gid_t)-1;
+
+	safe_free(sec_ctx_stack[sec_ctx_stack_ndx].groups);
+	sec_ctx_stack[sec_ctx_stack_ndx].ngroups = 0;
+
+	/* Pop back previous user */
+
+	sec_ctx_stack_ndx--;
+
+	gain_root();
+
+#ifdef HAVE_SETGROUPS
+	sys_setgroups(sec_ctx_stack[sec_ctx_stack_ndx].ngroups,
+		      sec_ctx_stack[sec_ctx_stack_ndx].groups);
+#endif
+
+	become_id(sec_ctx_stack[sec_ctx_stack_ndx].uid,
+		  sec_ctx_stack[sec_ctx_stack_ndx].gid);
+
+	/* Update current_user stuff */
+
+	current_user.uid = sec_ctx_stack[sec_ctx_stack_ndx].uid;
+	current_user.gid = sec_ctx_stack[sec_ctx_stack_ndx].gid;
+	current_user.ngroups = sec_ctx_stack[sec_ctx_stack_ndx].ngroups;
+	current_user.groups = sec_ctx_stack[sec_ctx_stack_ndx].groups;
+
+	DEBUG(3, ("popped off to sec ctx (%d, %d)\n", geteuid(), getegid()));
+
+	return True;
+}
+
+/* Initialise the security context system */
+
+void init_sec_ctx(void)
+{
+	int i;
+
+	/* Initialise security context stack */
+
+	memset(sec_ctx_stack, 0, sizeof(struct sec_ctx) * MAX_SEC_CTX_DEPTH);
+
+	for (i = 0; i < MAX_SEC_CTX_DEPTH; i++) {
+		sec_ctx_stack[i].uid = (uid_t)-1;
+		sec_ctx_stack[i].gid = (gid_t)-1;
+	}
+
+	/* Initialise first level of stack.  It is the current context */
+
+	sec_ctx_stack[0].uid = geteuid();
+	sec_ctx_stack[0].gid = getegid();
+
+	get_current_groups(&sec_ctx_stack[0].ngroups,
+			   &sec_ctx_stack[0].groups);
+
+	/* Initialise current_user global */
+
+	current_user.uid = sec_ctx_stack[sec_ctx_stack_ndx].uid;
+	current_user.gid = sec_ctx_stack[sec_ctx_stack_ndx].gid;
+	current_user.ngroups = sec_ctx_stack[sec_ctx_stack_ndx].ngroups;
+	current_user.groups = sec_ctx_stack[sec_ctx_stack_ndx].groups;
+
+	/* The conn and vuid are usually taken care of by other modules.
+	   We initialise them here. */
+
+	current_user.conn = NULL;
+	current_user.vuid = UID_FIELD_INVALID;
+}