policydb.c

linux 内核源代码

/*
 * Implementation of the policy database.
 *
 * Author : Stephen Smalley, <[e-mail]>
 */

/*
 * Updated: Trusted Computer Solutions, Inc. <[e-mail]>
 *
 *	Support for enhanced MLS infrastructure.
 *
 * Updated: Frank Mayer <[e-mail]> and Karl MacMillan <[e-mail]>
 *
 * 	Added conditional policy language extensions
 *
 * Copyright (C) 2004-2005 Trusted Computer Solutions, Inc.
 * Copyright (C) 2003 - 2004 Tresys Technology, LLC
 *	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/sched.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/errno.h>
#include "security.h"

#include "policydb.h"
#include "conditional.h"
#include "mls.h"

#define _DEBUG_HASHES

#ifdef DEBUG_HASHES
static char *symtab_name[SYM_NUM] = {
	"common prefixes",
	"classes",
	"roles",
	"types",
	"users",
	"bools",
	"levels",
	"categories",
};
#endif

int selinux_mls_enabled = 0;

static unsigned int symtab_sizes[SYM_NUM] = {
	2,
	32,
	16,
	512,
	128,
	16,
	16,
	16,
};

struct policydb_compat_info {
	int version;
	int sym_num;
	int ocon_num;
};

/* These need to be updated if SYM_NUM or OCON_NUM changes */
static struct policydb_compat_info policydb_compat[] = {
	{
		.version        = POLICYDB_VERSION_BASE,
		.sym_num        = SYM_NUM - 3,
		.ocon_num       = OCON_NUM - 1,
	},
	{
		.version        = POLICYDB_VERSION_BOOL,
		.sym_num        = SYM_NUM - 2,
		.ocon_num       = OCON_NUM - 1,
	},
	{
		.version        = POLICYDB_VERSION_IPV6,
		.sym_num        = SYM_NUM - 2,
		.ocon_num       = OCON_NUM,
	},
	{
		.version        = POLICYDB_VERSION_NLCLASS,
		.sym_num        = SYM_NUM - 2,
		.ocon_num       = OCON_NUM,
	},
	{
		.version        = POLICYDB_VERSION_MLS,
		.sym_num        = SYM_NUM,
		.ocon_num       = OCON_NUM,
	},
	{
		.version        = POLICYDB_VERSION_AVTAB,
		.sym_num        = SYM_NUM,
		.ocon_num       = OCON_NUM,
	},
	{
		.version        = POLICYDB_VERSION_RANGETRANS,
		.sym_num        = SYM_NUM,
		.ocon_num       = OCON_NUM,
	},
};

static struct policydb_compat_info *policydb_lookup_compat(int version)
{
	int i;
	struct policydb_compat_info *info = NULL;

	for (i = 0; i < ARRAY_SIZE(policydb_compat); i++) {
		if (policydb_compat[i].version == version) {
			info = &policydb_compat[i];
			break;
		}
	}
	return info;
}

/*
 * Initialize the role table.
 */
static int roles_init(struct policydb *p)
{
	char *key = NULL;
	int rc;
	struct role_datum *role;

	role = kzalloc(sizeof(*role), GFP_KERNEL);
	if (!role) {
		rc = -ENOMEM;
		goto out;
	}
	role->value = ++p->p_roles.nprim;
	if (role->value != OBJECT_R_VAL) {
		rc = -EINVAL;
		goto out_free_role;
	}
	key = kmalloc(strlen(OBJECT_R)+1,GFP_KERNEL);
	if (!key) {
		rc = -ENOMEM;
		goto out_free_role;
	}
	strcpy(key, OBJECT_R);
	rc = hashtab_insert(p->p_roles.table, key, role);
	if (rc)
		goto out_free_key;
out:
	return rc;

out_free_key:
	kfree(key);
out_free_role:
	kfree(role);
	goto out;
}

/*
 * Initialize a policy database structure.
 */
static int policydb_init(struct policydb *p)
{
	int i, rc;

	memset(p, 0, sizeof(*p));

	for (i = 0; i < SYM_NUM; i++) {
		rc = symtab_init(&p->symtab[i], symtab_sizes[i]);
		if (rc)
			goto out_free_symtab;
	}

	rc = avtab_init(&p->te_avtab);
	if (rc)
		goto out_free_symtab;

	rc = roles_init(p);
	if (rc)
		goto out_free_symtab;

	rc = cond_policydb_init(p);
	if (rc)
		goto out_free_symtab;

out:
	return rc;

out_free_symtab:
	for (i = 0; i < SYM_NUM; i++)
		hashtab_destroy(p->symtab[i].table);
	goto out;
}

/*
 * The following *_index functions are used to
 * define the val_to_name and val_to_struct arrays
 * in a policy database structure.  The val_to_name
 * arrays are used when converting security context
 * structures into string representations.  The
 * val_to_struct arrays are used when the attributes
 * of a class, role, or user are needed.
 */

static int common_index(void *key, void *datum, void *datap)
{
	struct policydb *p;
	struct common_datum *comdatum;

	comdatum = datum;
	p = datap;
	if (!comdatum->value || comdatum->value > p->p_commons.nprim)
		return -EINVAL;
	p->p_common_val_to_name[comdatum->value - 1] = key;
	return 0;
}

static int class_index(void *key, void *datum, void *datap)
{
	struct policydb *p;
	struct class_datum *cladatum;

	cladatum = datum;
	p = datap;
	if (!cladatum->value || cladatum->value > p->p_classes.nprim)
		return -EINVAL;
	p->p_class_val_to_name[cladatum->value - 1] = key;
	p->class_val_to_struct[cladatum->value - 1] = cladatum;
	return 0;
}

static int role_index(void *key, void *datum, void *datap)
{
	struct policydb *p;
	struct role_datum *role;

	role = datum;
	p = datap;
	if (!role->value || role->value > p->p_roles.nprim)
		return -EINVAL;
	p->p_role_val_to_name[role->value - 1] = key;
	p->role_val_to_struct[role->value - 1] = role;
	return 0;
}

static int type_index(void *key, void *datum, void *datap)
{
	struct policydb *p;
	struct type_datum *typdatum;

	typdatum = datum;
	p = datap;

	if (typdatum->primary) {
		if (!typdatum->value || typdatum->value > p->p_types.nprim)
			return -EINVAL;
		p->p_type_val_to_name[typdatum->value - 1] = key;
	}

	return 0;
}

static int user_index(void *key, void *datum, void *datap)
{
	struct policydb *p;
	struct user_datum *usrdatum;

	usrdatum = datum;
	p = datap;
	if (!usrdatum->value || usrdatum->value > p->p_users.nprim)
		return -EINVAL;
	p->p_user_val_to_name[usrdatum->value - 1] = key;
	p->user_val_to_struct[usrdatum->value - 1] = usrdatum;
	return 0;
}

static int sens_index(void *key, void *datum, void *datap)
{
	struct policydb *p;
	struct level_datum *levdatum;

	levdatum = datum;
	p = datap;

	if (!levdatum->isalias) {
		if (!levdatum->level->sens ||
		    levdatum->level->sens > p->p_levels.nprim)
			return -EINVAL;
		p->p_sens_val_to_name[levdatum->level->sens - 1] = key;
	}

	return 0;
}

static int cat_index(void *key, void *datum, void *datap)
{
	struct policydb *p;
	struct cat_datum *catdatum;

	catdatum = datum;
	p = datap;

	if (!catdatum->isalias) {
		if (!catdatum->value || catdatum->value > p->p_cats.nprim)
			return -EINVAL;
		p->p_cat_val_to_name[catdatum->value - 1] = key;
	}

	return 0;
}

static int (*index_f[SYM_NUM]) (void *key, void *datum, void *datap) =
{
	common_index,
	class_index,
	role_index,
	type_index,
	user_index,
	cond_index_bool,
	sens_index,
	cat_index,
};

/*
 * Define the common val_to_name array and the class
 * val_to_name and val_to_struct arrays in a policy
 * database structure.
 *
 * Caller must clean up upon failure.
 */
static int policydb_index_classes(struct policydb *p)
{
	int rc;

	p->p_common_val_to_name =
		kmalloc(p->p_commons.nprim * sizeof(char *), GFP_KERNEL);
	if (!p->p_common_val_to_name) {
		rc = -ENOMEM;
		goto out;
	}

	rc = hashtab_map(p->p_commons.table, common_index, p);
	if (rc)
		goto out;

	p->class_val_to_struct =
		kmalloc(p->p_classes.nprim * sizeof(*(p->class_val_to_struct)), GFP_KERNEL);
	if (!p->class_val_to_struct) {
		rc = -ENOMEM;
		goto out;
	}

	p->p_class_val_to_name =
		kmalloc(p->p_classes.nprim * sizeof(char *), GFP_KERNEL);
	if (!p->p_class_val_to_name) {
		rc = -ENOMEM;
		goto out;
	}

	rc = hashtab_map(p->p_classes.table, class_index, p);
out:
	return rc;
}

#ifdef DEBUG_HASHES
static void symtab_hash_eval(struct symtab *s)
{
	int i;

	for (i = 0; i < SYM_NUM; i++) {
		struct hashtab *h = s[i].table;
		struct hashtab_info info;

		hashtab_stat(h, &info);
		printk(KERN_DEBUG "%s:  %d entries and %d/%d buckets used, "
		       "longest chain length %d\n", symtab_name[i], h->nel,
		       info.slots_used, h->size, info.max_chain_len);
	}
}
#endif

/*
 * Define the other val_to_name and val_to_struct arrays
 * in a policy database structure.
 *
 * Caller must clean up on failure.
 */
static int policydb_index_others(struct policydb *p)
{
	int i, rc = 0;

	printk(KERN_DEBUG "security:  %d users, %d roles, %d types, %d bools",
	       p->p_users.nprim, p->p_roles.nprim, p->p_types.nprim, p->p_bools.nprim);
	if (selinux_mls_enabled)
		printk(", %d sens, %d cats", p->p_levels.nprim,
		       p->p_cats.nprim);
	printk("\n");

	printk(KERN_DEBUG "security:  %d classes, %d rules\n",
	       p->p_classes.nprim, p->te_avtab.nel);

#ifdef DEBUG_HASHES
	avtab_hash_eval(&p->te_avtab, "rules");
	symtab_hash_eval(p->symtab);
#endif

	p->role_val_to_struct =
		kmalloc(p->p_roles.nprim * sizeof(*(p->role_val_to_struct)),
		        GFP_KERNEL);
	if (!p->role_val_to_struct) {
		rc = -ENOMEM;
		goto out;
	}

	p->user_val_to_struct =
		kmalloc(p->p_users.nprim * sizeof(*(p->user_val_to_struct)),
		        GFP_KERNEL);
	if (!p->user_val_to_struct) {
		rc = -ENOMEM;
		goto out;
	}

	if (cond_init_bool_indexes(p)) {
		rc = -ENOMEM;
		goto out;
	}

	for (i = SYM_ROLES; i < SYM_NUM; i++) {
		p->sym_val_to_name[i] =
			kmalloc(p->symtab[i].nprim * sizeof(char *), GFP_KERNEL);
		if (!p->sym_val_to_name[i]) {
			rc = -ENOMEM;
			goto out;
		}
		rc = hashtab_map(p->symtab[i].table, index_f[i], p);
		if (rc)
			goto out;
	}

out:
	return rc;
}

/*
 * The following *_destroy functions are used to
 * free any memory allocated for each kind of
 * symbol data in the policy database.
 */

static int perm_destroy(void *key, void *datum, void *p)
{
	kfree(key);
	kfree(datum);
	return 0;
}

static int common_destroy(void *key, void *datum, void *p)
{
	struct common_datum *comdatum;

	kfree(key);
	comdatum = datum;
	hashtab_map(comdatum->permissions.table, perm_destroy, NULL);
	hashtab_destroy(comdatum->permissions.table);
	kfree(datum);
	return 0;
}

static int cls_destroy(void *key, void *datum, void *p)
{
	struct class_datum *cladatum;
	struct constraint_node *constraint, *ctemp;
	struct constraint_expr *e, *etmp;

	kfree(key);
	cladatum = datum;
	hashtab_map(cladatum->permissions.table, perm_destroy, NULL);
	hashtab_destroy(cladatum->permissions.table);
	constraint = cladatum->constraints;
	while (constraint) {
		e = constraint->expr;
		while (e) {
			ebitmap_destroy(&e->names);
			etmp = e;
			e = e->next;
			kfree(etmp);
		}
		ctemp = constraint;
		constraint = constraint->next;
		kfree(ctemp);
	}

	constraint = cladatum->validatetrans;
	while (constraint) {
		e = constraint->expr;
		while (e) {
			ebitmap_destroy(&e->names);
			etmp = e;
			e = e->next;
			kfree(etmp);
		}
		ctemp = constraint;
		constraint = constraint->next;
		kfree(ctemp);
	}

	kfree(cladatum->comkey);
	kfree(datum);
	return 0;
}

static int role_destroy(void *key, void *datum, void *p)
{
	struct role_datum *role;

	kfree(key);
	role = datum;
	ebitmap_destroy(&role->dominates);
	ebitmap_destroy(&role->types);
	kfree(datum);
	return 0;
}

static int type_destroy(void *key, void *datum, void *p)
{
	kfree(key);
	kfree(datum);
	return 0;
}

static int user_destroy(void *key, void *datum, void *p)
{
	struct user_datum *usrdatum;

	kfree(key);
	usrdatum = datum;
	ebitmap_destroy(&usrdatum->roles);
	ebitmap_destroy(&usrdatum->range.level[0].cat);
	ebitmap_destroy(&usrdatum->range.level[1].cat);
	ebitmap_destroy(&usrdatum->dfltlevel.cat);
	kfree(datum);
	return 0;
}

static int sens_destroy(void *key, void *datum, void *p)
{
	struct level_datum *levdatum;

	kfree(key);
	levdatum = datum;
	ebitmap_destroy(&levdatum->level->cat);
	kfree(levdatum->level);
	kfree(datum);
	return 0;
}

static int cat_destroy(void *key, void *datum, void *p)
{
	kfree(key);
	kfree(datum);
	return 0;
}

static int (*destroy_f[SYM_NUM]) (void *key, void *datum, void *datap) =
{
	common_destroy,
	cls_destroy,
	role_destroy,
	type_destroy,
	user_destroy,
	cond_destroy_bool,
	sens_destroy,
	cat_destroy,
};

static void ocontext_destroy(struct ocontext *c, int i)
{
	context_destroy(&c->context[0]);
	context_destroy(&c->context[1]);
	if (i == OCON_ISID || i == OCON_FS ||
	    i == OCON_NETIF || i == OCON_FSUSE)
		kfree(c->u.name);
	kfree(c);
}

/*
 * Free any memory allocated by a policy database structure.
 */
void policydb_destroy(struct policydb *p)
{
	struct ocontext *c, *ctmp;
	struct genfs *g, *gtmp;
	int i;
	struct role_allow *ra, *lra = NULL;
	struct role_trans *tr, *ltr = NULL;
	struct range_trans *rt, *lrt = NULL;

	for (i = 0; i < SYM_NUM; i++) {
		cond_resched();
		hashtab_map(p->symtab[i].table, destroy_f[i], NULL);
		hashtab_destroy(p->symtab[i].table);
	}

	for (i = 0; i < SYM_NUM; i++)
		kfree(p->sym_val_to_name[i]);

	kfree(p->class_val_to_struct);
	kfree(p->role_val_to_struct);
	kfree(p->user_val_to_struct);

	avtab_destroy(&p->te_avtab);

	for (i = 0; i < OCON_NUM; i++) {
		cond_resched();
		c = p->ocontexts[i];
		while (c) {
			ctmp = c;
			c = c->next;
			ocontext_destroy(ctmp,i);
		}
		p->ocontexts[i] = NULL;
	}

	g = p->genfs;
	while (g) {
		cond_resched();
		kfree(g->fstype);
		c = g->head;
		while (c) {
			ctmp = c;
			c = c->next;
			ocontext_destroy(ctmp,OCON_FSUSE);
		}
		gtmp = g;
		g = g->next;
		kfree(gtmp);
	}
	p->genfs = NULL;

	cond_policydb_destroy(p);

	for (tr = p->role_tr; tr; tr = tr->next) {
		cond_resched();
		kfree(ltr);
		ltr = tr;
	}
	kfree(ltr);

	for (ra = p->role_allow; ra; ra = ra -> next) {
		cond_resched();
		kfree(lra);