1 files changed, 424 insertions, 0 deletions
diff --git a/source3/smbd/sec_ctx.c b/source3/smbd/sec_ctx.c
new file mode 100644
index 0000000000..87bf8b1744
--- /dev/null
+++ b/source3/smbd/sec_ctx.c
@@ -0,0 +1,424 @@
+/* 
+   Unix SMB/CIFS implementation.
+   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 struct current_user current_user;
+
+struct sec_ctx {
+	uid_t uid;
+	uid_t gid;
+	int ngroups;
+	gid_t *groups;
+	NT_USER_TOKEN *token;
+};
+
+/* 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);
+
+	DO_PROFILE_INC(uid_changes);
+	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);
+	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 (non_root_mode()) {
+		return;
+	}
+
+	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.
+****************************************************************************/
+
+int get_current_groups(int *p_ngroups, gid_t **p_groups)
+{
+	int i;
+	gid_t grp;
+	int ngroups = sys_getgroups(0,&grp);
+	gid_t *groups;
+
+	(*p_ngroups) = 0;
+	(*p_groups) = NULL;
+
+	if (ngroups <= 0)
+		return -1;
+
+	if((groups = (gid_t *)malloc(sizeof(gid_t)*ngroups)) == NULL) {
+		DEBUG(0,("setup_groups malloc fail !\n"));
+		return -1;
+	}
+
+	if ((ngroups = sys_getgroups(ngroups,groups)) == -1) {
+		SAFE_FREE(groups);
+		return -1;
+	}
+
+	(*p_ngroups) = ngroups;
+	(*p_groups) = groups;
+
+	DEBUG( 3, ( "get_current_groups: user is in %u groups: ", ngroups));
+	for (i = 0; i < ngroups; i++ ) {
+		DEBUG( 3, ( "%s%d", (i ? ", " : ""), (int)groups[i] ) );
+	}
+	DEBUG( 3, ( "\n" ) );
+
+    return ngroups;
+}
+
+/****************************************************************************
+ Initialize the groups a user belongs to.
+****************************************************************************/
+
+BOOL initialise_groups(char *user, uid_t uid, gid_t gid)
+{
+	struct sec_ctx *prev_ctx_p;
+	BOOL result = True;
+
+	if (non_root_mode()) {
+		return True;
+	}
+
+	become_root();
+
+	/* Call initgroups() to get user groups */
+
+	if (initgroups(user,gid) == -1) {
+		DEBUG(0,("Unable to initgroups. Error was %s\n", strerror(errno) ));
+		if (getuid() == 0) {
+			if (gid < 0 || gid > 32767 || uid < 0 || uid > 32767) {
+				DEBUG(0,("This is probably a problem with the account %s\n", user));
+			}
+		}
+		result = False;
+		goto done;
+	}
+
+	/* Store groups in previous user's security context.  This will
+	   always work as the become_root() call increments the stack
+	   pointer. */
+
+	prev_ctx_p = &sec_ctx_stack[sec_ctx_stack_ndx - 1];
+
+	SAFE_FREE(prev_ctx_p->groups);
+	prev_ctx_p->ngroups = 0;
+
+	get_current_groups(&prev_ctx_p->ngroups, &prev_ctx_p->groups);
+
+ done:
+	unbecome_root();
+
+	return result;
+}
+
+/****************************************************************************
+ 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)
+{
+	struct sec_ctx *ctx_p;
+
+	/* Check we don't overflow our stack */
+
+	if (sec_ctx_stack_ndx == MAX_SEC_CTX_DEPTH) {
+		DEBUG(0, ("Security context stack overflow!\n"));
+		smb_panic("Security context stack overflow!\n");
+	}
+
+	/* Store previous user context */
+
+	sec_ctx_stack_ndx++;
+
+	ctx_p = &sec_ctx_stack[sec_ctx_stack_ndx];
+
+	ctx_p->uid = geteuid();
+	ctx_p->gid = getegid();
+
+ 	DEBUG(3, ("push_sec_ctx(%u, %u) : sec_ctx_stack_ndx = %d\n", 
+ 		  (unsigned int)ctx_p->uid, (unsigned int)ctx_p->gid, sec_ctx_stack_ndx ));
+
+	ctx_p->token = dup_nt_token(sec_ctx_stack[sec_ctx_stack_ndx-1].token);
+
+	ctx_p->ngroups = sys_getgroups(0, NULL);
+
+	if (ctx_p->ngroups != 0) {
+		if (!(ctx_p->groups = malloc(ctx_p->ngroups * sizeof(gid_t)))) {
+			DEBUG(0, ("Out of memory in push_sec_ctx()\n"));
+			delete_nt_token(&ctx_p->token);
+			return False;
+		}
+
+		sys_getgroups(ctx_p->ngroups, ctx_p->groups);
+	} else {
+		ctx_p->groups = NULL;
+	}
+
+	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, NT_USER_TOKEN *token)
+{
+	struct sec_ctx *ctx_p = &sec_ctx_stack[sec_ctx_stack_ndx];
+	
+	/* Set the security context */
+
+	DEBUG(3, ("setting sec ctx (%u, %u) - sec_ctx_stack_ndx = %d\n", 
+		(unsigned int)uid, (unsigned int)gid, sec_ctx_stack_ndx));
+
+	if (ngroups) {
+		int i;
+
+		DEBUG(3, ("%d user groups: \n", ngroups));
+		for (i = 0; i < ngroups; i++) {
+			DEBUGADD(3, ("%u ", (unsigned int)groups[i]));
+		}
+
+		DEBUG(3, ("\n"));
+	}
+	
+
+	gain_root();
+
+#ifdef HAVE_SETGROUPS
+	sys_setgroups(ngroups, groups);
+#endif
+
+	ctx_p->ngroups = ngroups;
+
+	SAFE_FREE(ctx_p->groups);
+	if (token && (token == ctx_p->token))
+		smb_panic("DUPLICATE_TOKEN");
+
+	delete_nt_token(&ctx_p->token);
+	
+	ctx_p->groups = memdup(groups, sizeof(gid_t) * ngroups);
+	ctx_p->token = dup_nt_token(token);
+
+	become_id(uid, gid);
+
+	ctx_p->uid = uid;
+	ctx_p->gid = gid;
+
+	/* Update current_user stuff */
+
+	current_user.uid = uid;
+	current_user.gid = gid;
+	current_user.ngroups = ngroups;
+	current_user.groups = groups;
+	current_user.nt_user_token = ctx_p->token;
+}
+
+/****************************************************************************
+ 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, NULL);
+}
+
+/****************************************************************************
+ Pop a security context from the stack.
+****************************************************************************/
+
+BOOL pop_sec_ctx(void)
+{
+	struct sec_ctx *ctx_p;
+	struct sec_ctx *prev_ctx_p;
+
+	/* Check for stack underflow */
+
+	if (sec_ctx_stack_ndx == 0) {
+		DEBUG(0, ("Security context stack underflow!\n"));
+		smb_panic("Security context stack underflow!\n");
+	}
+
+	ctx_p = &sec_ctx_stack[sec_ctx_stack_ndx];
+
+	/* Clear previous user info */
+
+	ctx_p->uid = (uid_t)-1;
+	ctx_p->gid = (gid_t)-1;
+
+	SAFE_FREE(ctx_p->groups);
+	ctx_p->ngroups = 0;
+
+	delete_nt_token(&ctx_p->token);
+
+	/* Pop back previous user */
+
+	sec_ctx_stack_ndx--;
+
+	gain_root();
+
+	prev_ctx_p = &sec_ctx_stack[sec_ctx_stack_ndx];
+
+#ifdef HAVE_SETGROUPS
+	sys_setgroups(prev_ctx_p->ngroups, prev_ctx_p->groups);
+#endif
+
+	become_id(prev_ctx_p->uid, prev_ctx_p->gid);
+
+	/* Update current_user stuff */
+
+	current_user.uid = prev_ctx_p->uid;
+	current_user.gid = prev_ctx_p->gid;
+	current_user.ngroups = prev_ctx_p->ngroups;
+	current_user.groups = prev_ctx_p->groups;
+	current_user.nt_user_token = prev_ctx_p->token;
+
+	DEBUG(3, ("pop_sec_ctx (%u, %u) - sec_ctx_stack_ndx = %d\n", 
+		(unsigned int)geteuid(), (unsigned int)getegid(), sec_ctx_stack_ndx));
+
+	return True;
+}
+
+/* Initialise the security context system */
+
+void init_sec_ctx(void)
+{
+	int i;
+	struct sec_ctx *ctx_p;
+
+	/* 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 */
+	ctx_p = &sec_ctx_stack[0];
+
+	ctx_p->uid = geteuid();
+	ctx_p->gid = getegid();
+
+	get_current_groups(&ctx_p->ngroups, &ctx_p->groups);
+
+	ctx_p->token = NULL; /* Maps to guest user. */
+
+	/* Initialise current_user global */
+
+	current_user.uid = ctx_p->uid;
+	current_user.gid = ctx_p->gid;
+	current_user.ngroups = ctx_p->ngroups;
+	current_user.groups = ctx_p->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;
+	current_user.nt_user_token = NULL;
+}