security/selinux/ss/services.c

/*
 * Implementation of the security services.
 *
 * Authors : Stephen Smalley, <sds@epoch.ncsc.mil>
 *           James Morris <jmorris@redhat.com>
 *
 * Updated: Trusted Computer Solutions, Inc. <dgoeddel@trustedcs.com>
 *
 *	Support for enhanced MLS infrastructure.
 *
 * Updated: Frank Mayer <mayerf@tresys.com> and Karl MacMillan <kmacmillan@tresys.com>
 *
 * 	Added conditional policy language extensions
 *
 * Copyright (C) 2004-2005 Trusted Computer Solutions, Inc.
 * Copyright (C) 2003 - 2004 Tresys Technology, LLC
 * Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
 *	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, version 2.
 */
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/in.h>
#include <linux/sched.h>
#include <linux/audit.h>
#include <asm/semaphore.h>
#include "flask.h"
#include "avc.h"
#include "avc_ss.h"
#include "security.h"
#include "context.h"
#include "policydb.h"
#include "sidtab.h"
#include "services.h"
#include "conditional.h"
#include "mls.h"

extern void selnl_notify_policyload(u32 seqno);
unsigned int policydb_loaded_version;

static DEFINE_RWLOCK(policy_rwlock);
#define POLICY_RDLOCK read_lock(&policy_rwlock)
#define POLICY_WRLOCK write_lock_irq(&policy_rwlock)
#define POLICY_RDUNLOCK read_unlock(&policy_rwlock)
#define POLICY_WRUNLOCK write_unlock_irq(&policy_rwlock)

static DECLARE_MUTEX(load_sem);
#define LOAD_LOCK down(&load_sem)
#define LOAD_UNLOCK up(&load_sem)

static struct sidtab sidtab;
struct policydb policydb;
int ss_initialized = 0;

/*
 * The largest sequence number that has been used when
 * providing an access decision to the access vector cache.
 * The sequence number only changes when a policy change
 * occurs.
 */
static u32 latest_granting = 0;

/* Forward declaration. */
static int context_struct_to_string(struct context *context, char **scontext,
				    u32 *scontext_len);

/*
 * Return the boolean value of a constraint expression
 * when it is applied to the specified source and target
 * security contexts.
 *
 * xcontext is a special beast...  It is used by the validatetrans rules
 * only.  For these rules, scontext is the context before the transition,
 * tcontext is the context after the transition, and xcontext is the context
 * of the process performing the transition.  All other callers of
 * constraint_expr_eval should pass in NULL for xcontext.
 */
static int constraint_expr_eval(struct context *scontext,
				struct context *tcontext,
				struct context *xcontext,
				struct constraint_expr *cexpr)
{
	u32 val1, val2;
	struct context *c;
	struct role_datum *r1, *r2;
	struct mls_level *l1, *l2;
	struct constraint_expr *e;
	int s[CEXPR_MAXDEPTH];
	int sp = -1;

	for (e = cexpr; e; e = e->next) {
		switch (e->expr_type) {
		case CEXPR_NOT:
			BUG_ON(sp < 0);
			s[sp] = !s[sp];
			break;
		case CEXPR_AND:
			BUG_ON(sp < 1);
			sp--;
			s[sp] &= s[sp+1];
			break;
		case CEXPR_OR:
			BUG_ON(sp < 1);
			sp--;
			s[sp] |= s[sp+1];
			break;
		case CEXPR_ATTR:
			if (sp == (CEXPR_MAXDEPTH-1))
				return 0;
			switch (e->attr) {
			case CEXPR_USER:
				val1 = scontext->user;
				val2 = tcontext->user;
				break;
			case CEXPR_TYPE:
				val1 = scontext->type;
				val2 = tcontext->type;
				break;
			case CEXPR_ROLE:
				val1 = scontext->role;
				val2 = tcontext->role;
				r1 = policydb.role_val_to_struct[val1 - 1];
				r2 = policydb.role_val_to_struct[val2 - 1];
				switch (e->op) {
				case CEXPR_DOM:
					s[++sp] = ebitmap_get_bit(&r1->dominates,
								  val2 - 1);
					continue;
				case CEXPR_DOMBY:
					s[++sp] = ebitmap_get_bit(&r2->dominates,
								  val1 - 1);
					continue;
				case CEXPR_INCOMP:
					s[++sp] = ( !ebitmap_get_bit(&r1->dominates,
								     val2 - 1) &&
						    !ebitmap_get_bit(&r2->dominates,
								     val1 - 1) );
					continue;
				default:
					break;
				}
				break;
			case CEXPR_L1L2:
				l1 = &(scontext->range.level[0]);
				l2 = &(tcontext->range.level[0]);
				goto mls_ops;
			case CEXPR_L1H2:
				l1 = &(scontext->range.level[0]);
				l2 = &(tcontext->range.level[1]);
				goto mls_ops;
			case CEXPR_H1L2:
				l1 = &(scontext->range.level[1]);
				l2 = &(tcontext->range.level[0]);
				goto mls_ops;
			case CEXPR_H1H2:
				l1 = &(scontext->range.level[1]);
				l2 = &(tcontext->range.level[1]);
				goto mls_ops;
			case CEXPR_L1H1:
				l1 = &(scontext->range.level[0]);
				l2 = &(scontext->range.level[1]);
				goto mls_ops;
			case CEXPR_L2H2:
				l1 = &(tcontext->range.level[0]);
				l2 = &(tcontext->range.level[1]);
				goto mls_ops;
mls_ops:
			switch (e->op) {
			case CEXPR_EQ:
				s[++sp] = mls_level_eq(l1, l2);
				continue;
			case CEXPR_NEQ:
				s[++sp] = !mls_level_eq(l1, l2);
				continue;
			case CEXPR_DOM:
				s[++sp] = mls_level_dom(l1, l2);
				continue;
			case CEXPR_DOMBY:
				s[++sp] = mls_level_dom(l2, l1);
				continue;
			case CEXPR_INCOMP:
				s[++sp] = mls_level_incomp(l2, l1);
				continue;
			default:
				BUG();
				return 0;
			}
			break;
			default:
				BUG();
				return 0;
			}

			switch (e->op) {
			case CEXPR_EQ:
				s[++sp] = (val1 == val2);
				break;
			case CEXPR_NEQ:
				s[++sp] = (val1 != val2);
				break;
			default:
				BUG();
				return 0;
			}
			break;
		case CEXPR_NAMES:
			if (sp == (CEXPR_MAXDEPTH-1))
				return 0;
			c = scontext;
			if (e->attr & CEXPR_TARGET)
				c = tcontext;
			else if (e->attr & CEXPR_XTARGET) {
				c = xcontext;
				if (!c) {
					BUG();
					return 0;
				}
			}
			if (e->attr & CEXPR_USER)
				val1 = c->user;
			else if (e->attr & CEXPR_ROLE)
				val1 = c->role;
			else if (e->attr & CEXPR_TYPE)
				val1 = c->type;
			else {
				BUG();
				return 0;
			}

			switch (e->op) {
			case CEXPR_EQ:
				s[++sp] = ebitmap_get_bit(&e->names, val1 - 1);
				break;
			case CEXPR_NEQ:
				s[++sp] = !ebitmap_get_bit(&e->names, val1 - 1);
				break;
			default:
				BUG();
				return 0;
			}
			break;
		default:
			BUG();
			return 0;
		}
	}

	BUG_ON(sp != 0);
	return s[0];
}

/*
 * Compute access vectors based on a context structure pair for
 * the permissions in a particular class.
 */
static int context_struct_compute_av(struct context *scontext,
				     struct context *tcontext,
				     u16 tclass,
				     u32 requested,
				     struct av_decision *avd)
{
	struct constraint_node *constraint;
	struct role_allow *ra;
	struct avtab_key avkey;
	struct avtab_datum *avdatum;
	struct class_datum *tclass_datum;

	/*
	 * Remap extended Netlink classes for old policy versions.
	 * Do this here rather than socket_type_to_security_class()
	 * in case a newer policy version is loaded, allowing sockets
	 * to remain in the correct class.
	 */
	if (policydb_loaded_version < POLICYDB_VERSION_NLCLASS)
		if (tclass >= SECCLASS_NETLINK_ROUTE_SOCKET &&
		    tclass <= SECCLASS_NETLINK_DNRT_SOCKET)
			tclass = SECCLASS_NETLINK_SOCKET;

	if (!tclass || tclass > policydb.p_classes.nprim) {
		printk(KERN_ERR "security_compute_av:  unrecognized class %d\n",
		       tclass);
		return -EINVAL;
	}
	tclass_datum = policydb.class_val_to_struct[tclass - 1];

	/*
	 * Initialize the access vectors to the default values.
	 */
	avd->allowed = 0;
	avd->decided = 0xffffffff;
	avd->auditallow = 0;
	avd->auditdeny = 0xffffffff;
	avd->seqno = latest_granting;

	/*
	 * If a specific type enforcement rule was defined for
	 * this permission check, then use it.
	 */
	avkey.source_type = scontext->type;
	avkey.target_type = tcontext->type;
	avkey.target_class = tclass;
	avdatum = avtab_search(&policydb.te_avtab, &avkey, AVTAB_AV);
	if (avdatum) {
		if (avdatum->specified & AVTAB_ALLOWED)
			avd->allowed = avtab_allowed(avdatum);
		if (avdatum->specified & AVTAB_AUDITDENY)
			avd->auditdeny = avtab_auditdeny(avdatum);
		if (avdatum->specified & AVTAB_AUDITALLOW)
			avd->auditallow = avtab_auditallow(avdatum);
	}

	/* Check conditional av table for additional permissions */
	cond_compute_av(&policydb.te_cond_avtab, &avkey, avd);

	/*
	 * Remove any permissions prohibited by a constraint (this includes
	 * the MLS policy).
	 */
	constraint = tclass_datum->constraints;
	while (constraint) {
		if ((constraint->permissions & (avd->allowed)) &&
		    !constraint_expr_eval(scontext, tcontext, NULL,
					  constraint->expr)) {
			avd->allowed = (avd->allowed) & ~(constraint->permissions);
		}
		constraint = constraint->next;
	}

	/*
	 * If checking process transition permission and the
	 * role is changing, then check the (current_role, new_role)
	 * pair.
	 */
	if (tclass == SECCLASS_PROCESS &&
	    (avd->allowed & (PROCESS__TRANSITION | PROCESS__DYNTRANSITION)) &&
	    scontext->role != tcontext->role) {
		for (ra = policydb.role_allow; ra; ra = ra->next) {
			if (scontext->role == ra->role &&
			    tcontext->role == ra->new_role)
				break;
		}
		if (!ra)
			avd->allowed = (avd->allowed) & ~(PROCESS__TRANSITION |
			                                PROCESS__DYNTRANSITION);
	}

	return 0;
}

static int security_validtrans_handle_fail(struct context *ocontext,
                                           struct context *ncontext,
                                           struct context *tcontext,
                                           u16 tclass)
{
	char *o = NULL, *n = NULL, *t = NULL;
	u32 olen, nlen, tlen;

	if (context_struct_to_string(ocontext, &o, &olen) < 0)
		goto out;
	if (context_struct_to_string(ncontext, &n, &nlen) < 0)
		goto out;
	if (context_struct_to_string(tcontext, &t, &tlen) < 0)
		goto out;
	audit_log(current->audit_context,
	          "security_validate_transition:  denied for"
	          " oldcontext=%s newcontext=%s taskcontext=%s tclass=%s",
	          o, n, t, policydb.p_class_val_to_name[tclass-1]);
out:
	kfree(o);
	kfree(n);
	kfree(t);

	if (!selinux_enforcing)
		return 0;
	return -EPERM;
}

int security_validate_transition(u32 oldsid, u32 newsid, u32 tasksid,
                                 u16 tclass)
{
	struct context *ocontext;
	struct context *ncontext;
	struct context *tcontext;
	struct class_datum *tclass_datum;
	struct constraint_node *constraint;
	int rc = 0;

	if (!ss_initialized)
		return 0;

	POLICY_RDLOCK;

	/*
	 * Remap extended Netlink classes for old policy versions.
	 * Do this here rather than socket_type_to_security_class()
	 * in case a newer policy version is loaded, allowing sockets
	 * to remain in the correct class.
	 */
	if (policydb_loaded_version < POLICYDB_VERSION_NLCLASS)
		if (tclass >= SECCLASS_NETLINK_ROUTE_SOCKET &&
		    tclass <= SECCLASS_NETLINK_DNRT_SOCKET)
			tclass = SECCLASS_NETLINK_SOCKET;

	if (!tclass || tclass > policydb.p_classes.nprim) {
		printk(KERN_ERR "security_validate_transition:  "
		       "unrecognized class %d\n", tclass);
		rc = -EINVAL;
		goto out;
	}
	tclass_datum = policydb.class_val_to_struct[tclass - 1];

	ocontext = sidtab_search(&sidtab, oldsid);
	if (!ocontext) {
		printk(KERN_ERR "security_validate_transition: "
		       " unrecognized SID %d\n", oldsid);
		rc = -EINVAL;
		goto out;
	}

	ncontext = sidtab_search(&sidtab, newsid);
	if (!ncontext) {
		printk(KERN_ERR "security_validate_transition: "
		       " unrecognized SID %d\n", newsid);
		rc = -EINVAL;
		goto out;
	}

	tcontext = sidtab_search(&sidtab, tasksid);
	if (!tcontext) {
		printk(KERN_ERR "security_validate_transition: "
		       " unrecognized SID %d\n", tasksid);
		rc = -EINVAL;
		goto out;
	}

	constraint = tclass_datum->validatetrans;
	while (constraint) {
		if (!constraint_expr_eval(ocontext, ncontext, tcontext,
		                          constraint->expr)) {
			rc = security_validtrans_handle_fail(ocontext, ncontext,
			                                     tcontext, tclass);
			goto out;
		}
		constraint = constraint->next;
	}

out:
	POLICY_RDUNLOCK;
	return rc;
}

/**
 * security_compute_av - Compute access vector decisions.
 * @ssid: source security identifier
 * @tsid: target security identifier
 * @tclass: target security class
 * @requested: requested permissions
 * @avd: access vector decisions
 *
 * Compute a set of access vector decisions based on the
 * SID pair (@ssid, @tsid) for the permissions in @tclass.
 * Return -%EINVAL if any of the parameters are invalid or %0
 * if the access vector decisions were computed successfully.
 */
int security_compute_av(u32 ssid,
			u32 tsid,
			u16 tclass,
			u32 requested,
			struct av_decision *avd)
{
	struct context *scontext = NULL, *tcontext = NULL;
	int rc = 0;

	if (!ss_initialized) {
		avd->allowed = requested;
		avd->decided = requested;
		avd->auditallow = 0;
		avd->auditdeny = 0xffffffff;
		avd->seqno = latest_granting;
		return 0;
	}

	POLICY_RDLOCK;

	scontext = sidtab_search(&sidtab, ssid);
	if (!scontext) {
		printk(KERN_ERR "security_compute_av:  unrecognized SID %d\n",
		       ssid);
		rc = -EINVAL;
		goto out;
	}
	tcontext = sidtab_search(&sidtab, tsid);
	if (!tcontext) {
		printk(KERN_ERR "security_compute_av:  unrecognized SID %d\n",
		       tsid);
		rc = -EINVAL;
		goto out;
	}

	rc = context_struct_compute_av(scontext, tcontext, tclass,
				       requested, avd);
out:
	POLICY_RDUNLOCK;
	return rc;
}

/*
 * Write the security context string representation of
 * the context structure `context' into a dynamically
 * allocated string of the correct size.  Set `*scontext'
 * to point to this string and set `*scontext_len' to
 * the length of the string.
 */
static int context_struct_to_string(struct context *context, char **scontext, u32 *scontext_len)
{
	char *scontextp;

	*scontext = NULL;
	*scontext_len = 0;

	/* Compute the size of the context. */
	*scontext_len += strlen(policydb.p_user_val_to_name[context->user - 1]) + 1;
	*scontext_len += strlen(policydb.p_role_val_to_name[context->role - 1]) + 1;
	*scontext_len += strlen(policydb.p_type_val_to_name[context->type - 1]) + 1;
	*scontext_len += mls_compute_context_len(context);

	/* Allocate space for the context; caller must free this space. */
	scontextp = kmalloc(*scontext_len, GFP_ATOMIC);
	if (!scontextp) {
		return -ENOMEM;
	}
	*scontext = scontextp;

	/*
	 * Copy the user name, role name and type name into the context.
	 */
	sprintf(scontextp, "%s:%s:%s",
		policydb.p_user_val_to_name[context->user - 1],
		policydb.p_role_val_to_name[context->role - 1],
		policydb.p_type_val_to_name[context->type - 1]);
	scontextp += strlen(policydb.p_user_val_to_name[context->user - 1]) +
	             1 + strlen(policydb.p_role_val_to_name[context->role - 1]) +
	             1 + strlen(policydb.p_type_val_to_name[context->type - 1]);

	mls_sid_to_context(context, &scontextp);

	*scontextp = 0;

	return 0;
}

#include "initial_sid_to_string.h"

/**
 * security_sid_to_context - Obtain a context for a given SID.
 * @sid: security identifier, SID
 * @scontext: security context
 * @scontext_len: length in bytes
 *
 * Write the string representation of the context associated with @sid
 * into a dynamically allocated string of the correct size.  Set @scontext
 * to point to this string and set @scontext_len to the length of the string.
 */
int security_sid_to_context(u32 sid, char **scontext, u32 *scontext_len)
{
	struct context *context;
	int rc = 0;

	if (!ss_initialized) {
		if (sid <= SECINITSID_NUM) {
			char *scontextp;

			*scontext_len = strlen(initial_sid_to_string[sid]) + 1;
			scontextp = kmalloc(*scontext_len,GFP_ATOMIC);
			strcpy(scontextp, initial_sid_to_string[sid]);
			*scontext = scontextp;
			goto out;
		}
		printk(KERN_ERR "security_sid_to_context:  called before initial "
		       "load_policy on unknown SID %d\n", sid);
		rc = -EINVAL;
		goto out;
	}
	POLICY_RDLOCK;
	context = sidtab_search(&sidtab, sid);
	if (!context) {
		printk(KERN_ERR "security_sid_to_context:  unrecognized SID "
		       "%d\n", sid);
		rc = -EINVAL;
		goto out_unlock;
	}
	rc = context_struct_to_string(context, scontext, scontext_len);
out_unlock:
	POLICY_RDUNLOCK;
out:
	return rc;

}

/**
 * security_context_to_sid - Obtain a SID for a given security context.
 * @scontext: security context
 * @scontext_len: length in bytes
 * @sid: security identifier, SID
 *
 * Obtains a SID associated with the security context that
 * has the string representation specified by @scontext.
 * Returns -%EINVAL if the context is invalid, -%ENOMEM if insufficient
 * memory is available, or 0 on success.
 */
int security_context_to_sid(char *scontext, u32 scontext_len, u32 *sid)
{
	char *scontext2;
	struct context context;
	struct role_datum *role;
	struct type_datum *typdatum;
	struct user_datum *usrdatum;
	char *scontextp, *p, oldc;
	int rc = 0;

	if (!ss_initialized) {
		int i;

		for (i = 1; i < SECINITSID_NUM; i++) {
			if (!strcmp(initial_sid_to_string[i], scontext)) {
				*sid = i;
				goto out;
			}
		}
		*sid = SECINITSID_KERNEL;
		goto out;
	}
	*sid = SECSID_NULL;

	/* Copy the string so that we can modify the copy as we parse it.
	   The string should already by null terminated, but we append a
	   null suffix to the copy to avoid problems with the existing
	   attr package, which doesn't view the null terminator as part
	   of the attribute value. */
	scontext2 = kmalloc(scontext_len+1,GFP_KERNEL);
	if (!scontext2) {
		rc = -ENOMEM;
		goto out;
	}
	memcpy(scontext2, scontext, scontext_len);
	scontext2[scontext_len] = 0;

	context_init(&context);
	*sid = SECSID_NULL;

	POLICY_RDLOCK;

	/* Parse the security context. */

	rc = -EINVAL;
	scontextp = (char *) scontext2;

	/* Extract the user. */
	p = scontextp;
	while (*p && *p != ':')
		p++;

	if (*p == 0)
		goto out_unlock;

	*p++ = 0;

	usrdatum = hashtab_search(policydb.p_users.table, scontextp);
	if (!usrdatum)
		goto out_unlock;

	context.user = usrdatum->value;

	/* Extract role. */
	scontextp = p;
	while (*p && *p != ':')
		p++;

	if (*p == 0)
		goto out_unlock;

	*p++ = 0;

	role = hashtab_search(policydb.p_roles.table, scontextp);
	if (!role)
		goto out_unlock;
	context.role = role->value;

	/* Extract type. */
	scontextp = p;
	while (*p && *p != ':')
		p++;
	oldc = *p;
	*p++ = 0;

	typdatum = hashtab_search(policydb.p_types.table, scontextp);
	if (!typdatum)
		goto out_unlock;

	context.type = typdatum->value;

	rc = mls_context_to_sid(oldc, &p, &context);
	if (rc)
		goto out_unlock;

	if ((p - scontext2) < scontext_len) {
		rc = -EINVAL;
		goto out_unlock;
	}

	/* Check the validity of the new context. */
	if (!policydb_context_isvalid(&policydb, &context)) {
		rc = -EINVAL;
		goto out_unlock;
	}
	/* Obtain the new sid. */
	rc = sidtab_context_to_sid(&sidtab, &context, sid);
out_unlock:
	POLICY_RDUNLOCK;
	context_destroy(&context);
	kfree(scontext2);
out:
	return rc;
}

static int compute_sid_handle_invalid_context(
	struct context *scontext,
	struct context *tcontext,
	u16 tclass,
	struct context *newcontext)
{
	char *s = NULL, *t = NULL, *n = NULL;
	u32 slen, tlen, nlen;

	if (context_struct_to_string(scontext, &s, &slen) < 0)
		goto out;
	if (context_struct_to_string(tcontext, &t, &tlen) < 0)
		goto out;
	if (context_struct_to_string(newcontext, &n, &nlen) < 0)
		goto out;
	audit_log(current->audit_context,
		  "security_compute_sid:  invalid context %s"
		  " for scontext=%s"
		  " tcontext=%s"
		  " tclass=%s",
		  n, s, t, policydb.p_class_val_to_name[tclass-1]);
out:
	kfree(s);
	kfree(t);
	kfree(n);
	if (!selinux_enforcing)
		return 0;
	return -EACCES;
}

static int security_compute_sid(u32 ssid,
				u32 tsid,
				u16 tclass,
				u32 specified,
				u32 *out_sid)
{
	struct context *scontext = NULL, *tcontext = NULL, newcontext;
	struct role_trans *roletr = NULL;
	struct avtab_key avkey;
	struct avtab_datum *avdatum;
	struct avtab_node *node;
	unsigned int type_change = 0;
	int rc = 0;

	if (!ss_initialized) {
		switch (tclass) {
		case SECCLASS_PROCESS:
			*out_sid = ssid;
			break;
		default:
			*out_sid = tsid;
			break;
		}
		goto out;
	}

	POLICY_RDLOCK;

	scontext = sidtab_search(&sidtab, ssid);
	if (!scontext) {
		printk(KERN_ERR "security_compute_sid:  unrecognized SID %d\n",
		       ssid);
		rc = -EINVAL;
		goto out_unlock;
	}
	tcontext = sidtab_search(&sidtab, tsid);
	if (!tcontext) {
		printk(KERN_ERR "security_compute_sid:  unrecognized SID %d\n",
		       tsid);
		rc = -EINVAL;
		goto out_unlock;
	}

	context_init(&newcontext);

	/* Set the user identity. */
	switch (specified) {
	case AVTAB_TRANSITION:
	case AVTAB_CHANGE:
		/* Use the process user identity. */
		newcontext.user = scontext->user;
		break;
	case AVTAB_MEMBER:
		/* Use the related object owner. */
		newcontext.user = tcontext->user;
		break;
	}

	/* Set the role and type to default values. */
	switch (tclass) {
	case SECCLASS_PROCESS:
		/* Use the current role and type of process. */
		newcontext.role = scontext->role;
		newcontext.type = scontext->type;
		break;
	default:
		/* Use the well-defined object role. */
		newcontext.role = OBJECT_R_VAL;
		/* Use the type of the related object. */
		newcontext.type = tcontext->type;
	}

	/* Look for a type transition/member/change rule. */
	avkey.source_type = scontext->type;
	avkey.target_type = tcontext->type;
	avkey.target_class = tclass;
	avdatum = avtab_search(&policydb.te_avtab, &avkey, AVTAB_TYPE);

	/* If no permanent rule, also check for enabled conditional rules */
	if(!avdatum) {
		node = avtab_search_node(&policydb.te_cond_avtab, &avkey, specified);
		for (; node != NULL; node = avtab_search_node_next(node, specified)) {
			if (node->datum.specified & AVTAB_ENABLED) {
				avdatum = &node->datum;
				break;
			}
		}
	}

	type_change = (avdatum && (avdatum->specified & specified));
	if (type_change) {
		/* Use the type from the type transition/member/change rule. */
		switch (specified) {
		case AVTAB_TRANSITION:
			newcontext.type = avtab_transition(avdatum);
			break;
		case AVTAB_MEMBER:
			newcontext.type = avtab_member(avdatum);
			break;
		case AVTAB_CHANGE:
			newcontext.type = avtab_change(avdatum);
			break;
		}
	}

	/* Check for class-specific changes. */
	switch (tclass) {
	case SECCLASS_PROCESS:
		if (specified & AVTAB_TRANSITION) {
			/* Look for a role transition rule. */
			for (roletr = policydb.role_tr; roletr;
			     roletr = roletr->next) {
				if (roletr->role == scontext->role &&
				    roletr->type == tcontext->type) {
					/* Use the role transition rule. */
					newcontext.role = roletr->new_role;
					break;
				}
			}
		}
		break;
	default:
		break;
	}

	/* Set the MLS attributes.
	   This is done last because it may allocate memory. */
	rc = mls_compute_sid(scontext, tcontext, tclass, specified, &newcontext);
	if (rc)
		goto out_unlock;

	/* Check the validity of the context. */
	if (!policydb_context_isvalid(&policydb, &newcontext)) {
		rc = compute_sid_handle_invalid_context(scontext,
							tcontext,
							tclass,
							&newcontext);
		if (rc)
			goto out_unlock;
	}
	/* Obtain the sid for the context. */
	rc = sidtab_context_to_sid(&sidtab, &newcontext, out_sid);
out_unlock:
	POLICY_RDUNLOCK;
	context_destroy(&newcontext);
out:
	return rc;
}

/**
 * security_transition_sid - Compute the SID for a new subject/object.
 * @ssid: source security identifier
 * @tsid: target security identifier
 * @tclass: target security class
 * @out_sid: security identifier for new subject/object
 *
 * Compute a SID to use for labeling a new subject or object in the
 * class @tclass based on a SID pair (@ssid, @tsid).
 * Return -%EINVAL if any of the parameters are invalid, -%ENOMEM
 * if insufficient memory is available, or %0 if the new SID was
 * computed successfully.
 */
int security_transition_sid(u32 ssid,
			    u32 tsid,
			    u16 tclass,
			    u32 *out_sid)
{
	return security_compute_sid(ssid, tsid, tclass, AVTAB_TRANSITION, out_sid);
}

/**
 * security_member_sid - Compute the SID for member selection.
 * @ssid: source security identifier
 * @tsid: target security identifier
 * @tclass: target security class
 * @out_sid: security identifier for selected member
 *
 * Compute a SID to use when selecting a member of a polyinstantiated
 * object of class @tclass based on a SID pair (@ssid, @tsid).
 * Return -%EINVAL if any of the parameters are invalid, -%ENOMEM
 * if insufficient memory is available, or %0 if the SID was
 * computed successfully.
 */
int security_member_sid(u32 ssid,
			u32 tsid,
			u16 tclass,
			u32 *out_sid)
{
	return security_compute_sid(ssid, tsid, tclass, AVTAB_MEMBER, out_sid);
}

/**
 * security_change_sid - Compute the SID for object relabeling.
 * @ssid: source security identifier
 * @tsid: target security identifier
 * @tclass: target security class
 * @out_sid: security identifier for selected member
 *
 * Compute a SID to use for relabeling an object of class @tclass
 * based on a SID pair (@ssid, @tsid).
 * Return -%EINVAL if any of the parameters are invalid, -%ENOMEM
 * if insufficient memory is available, or %0 if the SID was
 * computed successfully.
 */
int security_change_sid(u32 ssid,
			u32 tsid,
			u16 tclass,
			u32 *out_sid)
{
	return security_compute_sid(ssid, tsid, tclass, AVTAB_CHANGE, out_sid);
}

/*
 * Verify that each permission that is defined under the
 * existing policy is still defined with the same value
 * in the new policy.
 */
static int validate_perm(void *key, void *datum, void *p)
{
	struct hashtab *h;
	struct perm_datum *perdatum, *perdatum2;
	int rc = 0;


	h = p;
	perdatum = datum;

	perdatum2 = hashtab_search(h, key);
	if (!perdatum2) {
		printk(KERN_ERR "security:  permission %s disappeared",
		       (char *)key);
		rc = -ENOENT;
		goto out;
	}
	if (perdatum->value != perdatum2->value) {
		printk(KERN_ERR "security:  the value of permission %s changed",
		       (char *)key);
		rc = -EINVAL;
	}
out:
	return rc;
}

/*
 * Verify that each class that is defined under the
 * existing policy is still defined with the same
 * attributes in the new policy.
 */
static int validate_class(void *key, void *datum, void *p)
{
	struct policydb *newp;
	struct class_datum *cladatum, *cladatum2;
	int rc;

	newp = p;
	cladatum = datum;

	cladatum2 = hashtab_search(newp->p_classes.table, key);
	if (!cladatum2) {
		printk(KERN_ERR "security:  class %s disappeared\n",
		       (char *)key);
		rc = -ENOENT;
		goto out;
	}
	if (cladatum->value != cladatum2->value) {
		printk(KERN_ERR "security:  the value of class %s changed\n",
		       (char *)key);
		rc = -EINVAL;
		goto out;
	}
	if ((cladatum->comdatum && !cladatum2->comdatum) ||
	    (!cladatum->comdatum && cladatum2->comdatum)) {
		printk(KERN_ERR "security:  the inherits clause for the access "
		       "vector definition for class %s changed\n", (char *)key);
		rc = -EINVAL;
		goto out;
	}
	if (cladatum->comdatum) {
		rc = hashtab_map(cladatum->comdatum->permissions.table, validate_perm,
		                 cladatum2->comdatum->permissions.table);
		if (rc) {
			printk(" in the access vector definition for class "
			       "%s\n", (char *)key);
			goto out;
		}
	}
	rc = hashtab_map(cladatum->permissions.table, validate_perm,
	                 cladatum2->permissions.table);
	if (rc)
		printk(" in access vector definition for class %s\n",
		       (char *)key);
out:
	return rc;
}

/* Clone the SID into the new SID table. */
static int clone_sid(u32 sid,
		     struct context *context,
		     void *arg)
{
	struct sidtab *s = arg;

	return sidtab_insert(s, sid, context);
}

static inline int convert_context_handle_invalid_context(struct context *context)
{
	int rc = 0;

	if (selinux_enforcing) {
		rc = -EINVAL;
	} else {
		char *s;
		u32 len;

		context_struct_to_string(context, &s, &len);
		printk(KERN_ERR "security:  context %s is invalid\n", s);
		kfree(s);
	}
	return rc;
}

struct convert_context_args {
	struct policydb *oldp;
	struct policydb *newp;
};

/*
 * Convert the values in the security context
 * structure `c' from the values specified
 * in the policy `p->oldp' to the values specified
 * in the policy `p->newp'.  Verify that the
 * context is valid under the new policy.
 */
static int convert_context(u32 key,
			   struct context *c,
			   void *p)
{
	struct convert_context_args *args;
	struct context oldc;
	struct role_datum *role;
	struct type_datum *typdatum;
	struct user_datum *usrdatum;
	char *s;
	u32 len;
	int rc;

	args = p;

	rc = context_cpy(&oldc, c);
	if (rc)
		goto out;

	rc = -EINVAL;

	/* Convert the user. */
	usrdatum = hashtab_search(args->newp->p_users.table,
	                          args->oldp->p_user_val_to_name[c->user - 1]);
	if (!usrdatum) {
		goto bad;
	}
	c->user = usrdatum->value;

	/* Convert the role. */
	role = hashtab_search(args->newp->p_roles.table,
	                      args->oldp->p_role_val_to_name[c->role - 1]);
	if (!role) {
		goto bad;
	}
	c->role = role->value;

	/* Convert the type. */
	typdatum = hashtab_search(args->newp->p_types.table,
	                          args->oldp->p_type_val_to_name[c->type - 1]);
	if (!typdatum) {
		goto bad;
	}
	c->type = typdatum->value;

	rc = mls_convert_context(args->oldp, args->newp, c);
	if (rc)
		goto bad;

	/* Check the validity of the new context. */
	if (!policydb_context_isvalid(args->newp, c)) {
		rc = convert_context_handle_invalid_context(&oldc);
		if (rc)
			goto bad;
	}

	context_destroy(&oldc);
out:
	return rc;
bad:
	context_struct_to_string(&oldc, &s, &len);
	context_destroy(&oldc);
	printk(KERN_ERR "security:  invalidating context %s\n", s);
	kfree(s);
	goto out;
}

extern void selinux_complete_init(void);

/**
 * security_load_policy - Load a security policy configuration.
 * @data: binary policy data
 * @len: length of data in bytes
 *
 * Load a new set of security policy configuration data,
 * validate it and convert the SID table as necessary.
 * This function will flush the access vector cache after
 * loading the new policy.
 */
int security_load_policy(void *data, size_t len)
{
	struct policydb oldpolicydb, newpolicydb;
	struct sidtab oldsidtab, newsidtab;
	struct convert_context_args args;
	u32 seqno;
	int rc = 0;
	struct policy_file file = { data, len }, *fp = &file;

	LOAD_LOCK;

	if (!ss_initialized) {
		avtab_cache_init();
		if (policydb_read(&policydb, fp)) {
			LOAD_UNLOCK;
			avtab_cache_destroy();
			return -EINVAL;
		}
		if (policydb_load_isids(&policydb, &sidtab)) {
			LOAD_UNLOCK;
			policydb_destroy(&policydb);
			avtab_cache_destroy();
			return -EINVAL;
		}
		policydb_loaded_version = policydb.policyvers;
		ss_initialized = 1;

		LOAD_UNLOCK;
		selinux_complete_init();
		return 0;
	}

#if 0
	sidtab_hash_eval(&sidtab, "sids");
#endif

	if (policydb_read(&newpolicydb, fp)) {
		LOAD_UNLOCK;
		return -EINVAL;
	}

	sidtab_init(&newsidtab);

	/* Verify that the existing classes did not change. */
	if (hashtab_map(policydb.p_classes.table, validate_class, &newpolicydb)) {
		printk(KERN_ERR "security:  the definition of an existing "
		       "class changed\n");
		rc = -EINVAL;
		goto err;
	}

	/* Clone the SID table. */
	sidtab_shutdown(&sidtab);
	if (sidtab_map(&sidtab, clone_sid, &newsidtab)) {
		rc = -ENOMEM;
		goto err;
	}

	/* Convert the internal representations of contexts
	   in the new SID table and remove invalid SIDs. */
	args.oldp = &policydb;
	args.newp = &newpolicydb;
	sidtab_map_remove_on_error(&newsidtab, convert_context, &args);

	/* Save the old policydb and SID table to free later. */
	memcpy(&oldpolicydb, &policydb, sizeof policydb);
	sidtab_set(&oldsidtab, &sidtab);

	/* Install the new policydb and SID table. */
	POLICY_WRLOCK;
	memcpy(&policydb, &newpolicydb, sizeof policydb);
	sidtab_set(&sidtab, &newsidtab);
	seqno = ++latest_granting;
	policydb_loaded_version = policydb.policyvers;
	POLICY_WRUNLOCK;
	LOAD_UNLOCK;

	/* Free the old policydb and SID table. */
	policydb_destroy(&oldpolicydb);
	sidtab_destroy(&oldsidtab);

	avc_ss_reset(seqno);
	selnl_notify_policyload(seqno);

	return 0;

err:
	LOAD_UNLOCK;
	sidtab_destroy(&newsidtab);
	policydb_destroy(&newpolicydb);
	return rc;

}

/**
 * security_port_sid - Obtain the SID for a port.
 * @domain: communication domain aka address family
 * @type: socket type
 * @protocol: protocol number
 * @port: port number
 * @out_sid: security identifier
 */
int security_port_sid(u16 domain,
		      u16 type,
		      u8 protocol,
		      u16 port,
		      u32 *out_sid)
{
	struct ocontext *c;
	int rc = 0;

	POLICY_RDLOCK;

	c = policydb.ocontexts[OCON_PORT];
	while (c) {
		if (c->u.port.protocol == protocol &&
		    c->u.port.low_port <= port &&
		    c->u.port.high_port >= port)
			break;
		c = c->next;
	}

	if (c) {
		if (!c->sid[0]) {
			rc = sidtab_context_to_sid(&sidtab,
						   &c->context[0],
						   &c->sid[0]);
			if (rc)
				goto out;
		}
		*out_sid = c->sid[0];
	} else {
		*out_sid = SECINITSID_PORT;
	}

out:
	POLICY_RDUNLOCK;
	return rc;
}

/**
 * security_netif_sid - Obtain the SID for a network interface.
 * @name: interface name
 * @if_sid: interface SID
 * @msg_sid: default SID for received packets
 */
int security_netif_sid(char *name,
		       u32 *if_sid,
		       u32 *msg_sid)
{
	int rc = 0;
	struct ocontext *c;

	POLICY_RDLOCK;

	c = policydb.ocontexts[OCON_NETIF];
	while (c) {
		if (strcmp(name, c->u.name) == 0)
			break;
		c = c->next;
	}

	if (c) {
		if (!c->sid[0] || !c->sid[1]) {
			rc = sidtab_context_to_sid(&sidtab,
						  &c->context[0],
						  &c->sid[0]);
			if (rc)
				goto out;
			rc = sidtab_context_to_sid(&sidtab,
						   &c->context[1],
						   &c->sid[1]);
			if (rc)
				goto out;
		}
		*if_sid = c->sid[0];
		*msg_sid = c->sid[1];
	} else {
		*if_sid = SECINITSID_NETIF;
		*msg_sid = SECINITSID_NETMSG;
	}

out:
	POLICY_RDUNLOCK;
	return rc;
}

static int match_ipv6_addrmask(u32 *input, u32 *addr, u32 *mask)
{
	int i, fail = 0;

	for(i = 0; i < 4; i++)
		if(addr[i] != (input[i] & mask[i])) {
			fail = 1;
			break;
		}

	return !fail;
}

/**
 * security_node_sid - Obtain the SID for a node (host).
 * @domain: communication domain aka address family
 * @addrp: address
 * @addrlen: address length in bytes
 * @out_sid: security identifier
 */
int security_node_sid(u16 domain,
		      void *addrp,
		      u32 addrlen,
		      u32 *out_sid)
{
	int rc = 0;
	struct ocontext *c;

	POLICY_RDLOCK;

	switch (domain) {
	case AF_INET: {
		u32 addr;

		if (addrlen != sizeof(u32)) {
			rc = -EINVAL;
			goto out;
		}

		addr = *((u32 *)addrp);

		c = policydb.ocontexts[OCON_NODE];
		while (c) {
			if (c->u.node.addr == (addr & c->u.node.mask))
				break;
			c = c->next;
		}
		break;
	}

	case AF_INET6:
		if (addrlen != sizeof(u64) * 2) {
			rc = -EINVAL;
			goto out;
		}
		c = policydb.ocontexts[OCON_NODE6];
		while (c) {
			if (match_ipv6_addrmask(addrp, c->u.node6.addr,
						c->u.node6.mask))
				break;
			c = c->next;
		}
		break;

	default:
		*out_sid = SECINITSID_NODE;
		goto out;
	}

	if (c) {
		if (!c->sid[0]) {
			rc = sidtab_context_to_sid(&sidtab,
						   &c->context[0],
						   &c->sid[0]);
			if (rc)
				goto out;
		}
		*out_sid = c->sid[0];
	} else {
		*out_sid = SECINITSID_NODE;
	}

out:
	POLICY_RDUNLOCK;
	return rc;
}

#define SIDS_NEL 25

/**
 * security_get_user_sids - Obtain reachable SIDs for a user.
 * @fromsid: starting SID
 * @username: username
 * @sids: array of reachable SIDs for user
 * @nel: number of elements in @sids
 *
 * Generate the set of SIDs for legal security contexts
 * for a given user that can be reached by @fromsid.
 * Set *@sids to point to a dynamically allocated
 * array containing the set of SIDs.  Set *@nel to the
 * number of elements in the array.
 */

int security_get_user_sids(u32 fromsid,
	                   char *username,
			   u32 **sids,
			   u32 *nel)
{
	struct context *fromcon, usercon;
	u32 *mysids, *mysids2, sid;
	u32 mynel = 0, maxnel = SIDS_NEL;
	struct user_datum *user;
	struct role_datum *role;
	struct av_decision avd;
	int rc = 0, i, j;

	if (!ss_initialized) {
		*sids = NULL;
		*nel = 0;
		goto out;
	}

	POLICY_RDLOCK;

	fromcon = sidtab_search(&sidtab, fromsid);
	if (!fromcon) {
		rc = -EINVAL;
		goto out_unlock;
	}

	user = hashtab_search(policydb.p_users.table, username);
	if (!user) {
		rc = -EINVAL;
		goto out_unlock;
	}
	usercon.user = user->value;

	mysids = kmalloc(maxnel*sizeof(*mysids), GFP_ATOMIC);
	if (!mysids) {
		rc = -ENOMEM;
		goto out_unlock;
	}
	memset(mysids, 0, maxnel*sizeof(*mysids));

	for (i = ebitmap_startbit(&user->roles); i < ebitmap_length(&user->roles); i++) {
		if (!ebitmap_get_bit(&user->roles, i))
			continue;
		role = policydb.role_val_to_struct[i];
		usercon.role = i+1;
		for (j = ebitmap_startbit(&role->types); j < ebitmap_length(&role->types); j++) {
			if (!ebitmap_get_bit(&role->types, j))
				continue;
			usercon.type = j+1;

			if (mls_setup_user_range(fromcon, user, &usercon))
				continue;

			rc = context_struct_compute_av(fromcon, &usercon,
						       SECCLASS_PROCESS,
						       PROCESS__TRANSITION,
						       &avd);
			if (rc ||  !(avd.allowed & PROCESS__TRANSITION))
				continue;
			rc = sidtab_context_to_sid(&sidtab, &usercon, &sid);
			if (rc) {
				kfree(mysids);
				goto out_unlock;
			}
			if (mynel < maxnel) {
				mysids[mynel++] = sid;
			} else {
				maxnel += SIDS_NEL;
				mysids2 = kmalloc(maxnel*sizeof(*mysids2), GFP_ATOMIC);
				if (!mysids2) {
					rc = -ENOMEM;
					kfree(mysids);
					goto out_unlock;
				}
				memset(mysids2, 0, maxnel*sizeof(*mysids2));
				memcpy(mysids2, mysids, mynel * sizeof(*mysids2));
				kfree(mysids);
				mysids = mysids2;
				mysids[mynel++] = sid;
			}
		}
	}

	*sids = mysids;
	*nel = mynel;

out_unlock:
	POLICY_RDUNLOCK;
out:
	return rc;
}

/**
 * security_genfs_sid - Obtain a SID for a file in a filesystem
 * @fstype: filesystem type
 * @path: path from root of mount
 * @sclass: file security class
 * @sid: SID for path
 *
 * Obtain a SID to use for a file in a filesystem that
 * cannot support xattr or use a fixed labeling behavior like
 * transition SIDs or task SIDs.
 */
int security_genfs_sid(const char *fstype,
	               char *path,
		       u16 sclass,
		       u32 *sid)
{
	int len;
	struct genfs *genfs;
	struct ocontext *c;
	int rc = 0, cmp = 0;

	POLICY_RDLOCK;

	for (genfs = policydb.genfs; genfs; genfs = genfs->next) {
		cmp = strcmp(fstype, genfs->fstype);
		if (cmp <= 0)
			break;
	}

	if (!genfs || cmp) {
		*sid = SECINITSID_UNLABELED;
		rc = -ENOENT;
		goto out;
	}

	for (c = genfs->head; c; c = c->next) {
		len = strlen(c->u.name);
		if ((!c->v.sclass || sclass == c->v.sclass) &&
		    (strncmp(c->u.name, path, len) == 0))
			break;
	}

	if (!c) {
		*sid = SECINITSID_UNLABELED;
		rc = -ENOENT;
		goto out;
	}

	if (!c->sid[0]) {
		rc = sidtab_context_to_sid(&sidtab,
					   &c->context[0],
					   &c->sid[0]);
		if (rc)
			goto out;
	}

	*sid = c->sid[0];
out:
	POLICY_RDUNLOCK;
	return rc;
}

/**
 * security_fs_use - Determine how to handle labeling for a filesystem.
 * @fstype: filesystem type
 * @behavior: labeling behavior
 * @sid: SID for filesystem (superblock)
 */
int security_fs_use(
	const char *fstype,
	unsigned int *behavior,
	u32 *sid)
{
	int rc = 0;
	struct ocontext *c;

	POLICY_RDLOCK;

	c = policydb.ocontexts[OCON_FSUSE];
	while (c) {
		if (strcmp(fstype, c->u.name) == 0)
			break;
		c = c->next;
	}

	if (c) {
		*behavior = c->v.behavior;
		if (!c->sid[0]) {
			rc = sidtab_context_to_sid(&sidtab,
						   &c->context[0],
						   &c->sid[0]);
			if (rc)
				goto out;
		}
		*sid = c->sid[0];
	} else {
		rc = security_genfs_sid(fstype, "/", SECCLASS_DIR, sid);
		if (rc) {
			*behavior = SECURITY_FS_USE_NONE;
			rc = 0;
		} else {
			*behavior = SECURITY_FS_USE_GENFS;
		}
	}

out:
	POLICY_RDUNLOCK;
	return rc;
}

int security_get_bools(int *len, char ***names, int **values)
{
	int i, rc = -ENOMEM;

	POLICY_RDLOCK;
	*names = NULL;
	*values = NULL;

	*len = policydb.p_bools.nprim;
	if (!*len) {
		rc = 0;
		goto out;
	}

	*names = (char**)kmalloc(sizeof(char*) * *len, GFP_ATOMIC);
	if (!*names)
		goto err;
	memset(*names, 0, sizeof(char*) * *len);

	*values = (int*)kmalloc(sizeof(int) * *len, GFP_ATOMIC);
	if (!*values)
		goto err;

	for (i = 0; i < *len; i++) {
		size_t name_len;
		(*values)[i] = policydb.bool_val_to_struct[i]->state;
		name_len = strlen(policydb.p_bool_val_to_name[i]) + 1;
		(*names)[i] = (char*)kmalloc(sizeof(char) * name_len, GFP_ATOMIC);
		if (!(*names)[i])
			goto err;
		strncpy((*names)[i], policydb.p_bool_val_to_name[i], name_len);
		(*names)[i][name_len - 1] = 0;
	}
	rc = 0;
out:
	POLICY_RDUNLOCK;
	return rc;
err:
	if (*names) {
		for (i = 0; i < *len; i++)
			if ((*names)[i])
				kfree((*names)[i]);
	}
	if (*values)
		kfree(*values);
	goto out;
}


int security_set_bools(int len, int *values)
{
	int i, rc = 0;
	int lenp, seqno = 0;
	struct cond_node *cur;

	POLICY_WRLOCK;

	lenp = policydb.p_bools.nprim;
	if (len != lenp) {
		rc = -EFAULT;
		goto out;
	}

	printk(KERN_INFO "security: committed booleans { ");
	for (i = 0; i < len; i++) {
		if (values[i]) {
			policydb.bool_val_to_struct[i]->state = 1;
		} else {
			policydb.bool_val_to_struct[i]->state = 0;
		}
		if (i != 0)
			printk(", ");
		printk("%s:%d", policydb.p_bool_val_to_name[i],
		       policydb.bool_val_to_struct[i]->state);
	}
	printk(" }\n");

	for (cur = policydb.cond_list; cur != NULL; cur = cur->next) {
		rc = evaluate_cond_node(&policydb, cur);
		if (rc)
			goto out;
	}

	seqno = ++latest_granting;

out:
	POLICY_WRUNLOCK;
	if (!rc) {
		avc_ss_reset(seqno);
		selnl_notify_policyload(seqno);
	}
	return rc;
}

int security_get_bool_value(int bool)
{
	int rc = 0;
	int len;

	POLICY_RDLOCK;

	len = policydb.p_bools.nprim;
	if (bool >= len) {
		rc = -EFAULT;
		goto out;
	}

	rc = policydb.bool_val_to_struct[bool]->state;
out:
	POLICY_RDUNLOCK;
	return rc;
}