/* SPDX-License-Identifier: GPL-2.0-only */
/* Authors: Karl MacMillan <[email protected]>
* Frank Mayer <[email protected]>
* Copyright (C) 2003 - 2004 Tresys Technology, LLC
*/
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include "security.h"
#include "conditional.h"
#include "services.h"
/*
* cond_evaluate_expr evaluates a conditional expr
* in reverse polish notation. It returns true (1), false (0),
* or undefined (-1). Undefined occurs when the expression
* exceeds the stack depth of COND_EXPR_MAXDEPTH.
*/
static int cond_evaluate_expr(struct policydb *p, struct cond_expr *expr)
{
u32 i;
int s[COND_EXPR_MAXDEPTH];
int sp = -1;
if (expr->len == 0)
return -1;
for (i = 0; i < expr->len; i++) {
struct cond_expr_node *node = &expr->nodes[i];
switch (node->expr_type) {
case COND_BOOL:
if (sp == (COND_EXPR_MAXDEPTH - 1))
return -1;
sp++;
s[sp] = p->bool_val_to_struct[node->boolean - 1]->state;
break;
case COND_NOT:
if (sp < 0)
return -1;
s[sp] = !s[sp];
break;
case COND_OR:
if (sp < 1)
return -1;
sp--;
s[sp] |= s[sp + 1];
break;
case COND_AND:
if (sp < 1)
return -1;
sp--;
s[sp] &= s[sp + 1];
break;
case COND_XOR:
if (sp < 1)
return -1;
sp--;
s[sp] ^= s[sp + 1];
break;
case COND_EQ:
if (sp < 1)
return -1;
sp--;
s[sp] = (s[sp] == s[sp + 1]);
break;
case COND_NEQ:
if (sp < 1)
return -1;
sp--;
s[sp] = (s[sp] != s[sp + 1]);
break;
default:
return -1;
}
}
return s[0];
}
/*
* evaluate_cond_node evaluates the conditional stored in
* a struct cond_node and if the result is different than the
* current state of the node it sets the rules in the true/false
* list appropriately. If the result of the expression is undefined
* all of the rules are disabled for safety.
*/
static void evaluate_cond_node(struct policydb *p, struct cond_node *node)
{
struct avtab_node *avnode;
int new_state;
u32 i;
new_state = cond_evaluate_expr(p, &node->expr);
if (new_state != node->cur_state) {
node->cur_state = new_state;
if (new_state == -1)
pr_err("SELinux: expression result was undefined - disabling all rules.\n");
/* turn the rules on or off */
for (i = 0; i < node->true_list.len; i++) {
avnode = node->true_list.nodes[i];
if (new_state <= 0)
avnode->key.specified &= ~AVTAB_ENABLED;
else
avnode->key.specified |= AVTAB_ENABLED;
}
for (i = 0; i < node->false_list.len; i++) {
avnode = node->false_list.nodes[i];
/* -1 or 1 */
if (new_state)
avnode->key.specified &= ~AVTAB_ENABLED;
else
avnode->key.specified |= AVTAB_ENABLED;
}
}
}
void evaluate_cond_nodes(struct policydb *p)
{
u32 i;
for (i = 0; i < p->cond_list_len; i++)
evaluate_cond_node(p, &p->cond_list[i]);
}
void cond_policydb_init(struct policydb *p)
{
p->bool_val_to_struct = NULL;
p->cond_list = NULL;
p->cond_list_len = 0;
avtab_init(&p->te_cond_avtab);
}
static void cond_node_destroy(struct cond_node *node)
{
kfree(node->expr.nodes);
/* the avtab_ptr_t nodes are destroyed by the avtab */
kfree(node->true_list.nodes);
kfree(node->false_list.nodes);
}
static void cond_list_destroy(struct policydb *p)
{
u32 i;
for (i = 0; i < p->cond_list_len; i++)
cond_node_destroy(&p->cond_list[i]);
kfree(p->cond_list);
p->cond_list = NULL;
p->cond_list_len = 0;
}
void cond_policydb_destroy(struct policydb *p)
{
kfree(p->bool_val_to_struct);
avtab_destroy(&p->te_cond_avtab);
cond_list_destroy(p);
}
int cond_init_bool_indexes(struct policydb *p)
{
kfree(p->bool_val_to_struct);
p->bool_val_to_struct = kmalloc_array(
p->p_bools.nprim, sizeof(*p->bool_val_to_struct), GFP_KERNEL);
if (!p->bool_val_to_struct)
return -ENOMEM;
avtab_hash_eval(&p->te_cond_avtab, "conditional_rules");
return 0;
}
int cond_destroy_bool(void *key, void *datum, void *p)
{
kfree(key);
kfree(datum);
return 0;
}
int cond_index_bool(void *key, void *datum, void *datap)
{
struct policydb *p;
struct cond_bool_datum *booldatum;
booldatum = datum;
p = datap;
if (!booldatum->value || booldatum->value > p->p_bools.nprim)
return -EINVAL;
p->sym_val_to_name[SYM_BOOLS][booldatum->value - 1] = key;
p->bool_val_to_struct[booldatum->value - 1] = booldatum;
return 0;
}
static int bool_isvalid(struct cond_bool_datum *b)
{
if (!(b->state == 0 || b->state == 1))
return 0;
return 1;
}
int cond_read_bool(struct policydb *p, struct symtab *s, void *fp)
{
char *key = NULL;
struct cond_bool_datum *booldatum;
__le32 buf[3];
u32 len;
int rc;
booldatum = kzalloc(sizeof(*booldatum), GFP_KERNEL);
if (!booldatum)
return -ENOMEM;
rc = next_entry(buf, fp, sizeof(buf));
if (rc)
goto err;
booldatum->value = le32_to_cpu(buf[0]);
booldatum->state = le32_to_cpu(buf[1]);
rc = -EINVAL;
if (!bool_isvalid(booldatum))
goto err;
len = le32_to_cpu(buf[2]);
if (((len == 0) || (len == (u32)-1)))
goto err;
rc = -ENOMEM;
key = kmalloc(len + 1, GFP_KERNEL);
if (!key)
goto err;
rc = next_entry(key, fp, len);
if (rc)
goto err;
key[len] = '\0';
rc = symtab_insert(s, key, booldatum);
if (rc)
goto err;
return 0;
err:
cond_destroy_bool(key, booldatum, NULL);
return rc;
}
struct cond_insertf_data {
struct policydb *p;
struct avtab_node **dst;
struct cond_av_list *other;
};
static int cond_insertf(struct avtab *a, const struct avtab_key *k,
const struct avtab_datum *d, void *ptr)
{
struct cond_insertf_data *data = ptr;
struct policydb *p = data->p;
struct cond_av_list *other = data->other;
struct avtab_node *node_ptr;
u32 i;
bool found;
/*
* For type rules we have to make certain there aren't any
* conflicting rules by searching the te_avtab and the
* cond_te_avtab.
*/
if (k->specified & AVTAB_TYPE) {
if (avtab_search_node(&p->te_avtab, k)) {
pr_err("SELinux: type rule already exists outside of a conditional.\n");
return -EINVAL;
}
/*
* If we are reading the false list other will be a pointer to
* the true list. We can have duplicate entries if there is only
* 1 other entry and it is in our true list.
*
* If we are reading the true list (other == NULL) there shouldn't
* be any other entries.
*/
if (other) {
node_ptr = avtab_search_node(&p->te_cond_avtab, k);
if (node_ptr) {
if (avtab_search_node_next(node_ptr,
k->specified)) {
pr_err("SELinux: too many conflicting type rules.\n");
return -EINVAL;
}
found = false;
for (i = 0; i < other->len; i++) {
if (other->nodes[i] == node_ptr) {
found = true;
break;
}
}
if (!found) {
pr_err("SELinux: conflicting type rules.\n");
return -EINVAL;
}
}
} else {
if (avtab_search_node(&p->te_cond_avtab, k)) {
pr_err("SELinux: conflicting type rules when adding type rule for true.\n");
return -EINVAL;
}
}
}
node_ptr = avtab_insert_nonunique(&p->te_cond_avtab, k, d);
if (!node_ptr) {
pr_err("SELinux: could not insert rule.\n");
return -ENOMEM;
}
*data->dst = node_ptr;
return 0;
}
static int cond_read_av_list(struct policydb *p, void *fp,
struct cond_av_list *list,
struct cond_av_list *other)
{
int rc;
__le32 buf[1];
u32 i, len;
struct cond_insertf_data data;
rc = next_entry(buf, fp, sizeof(u32));
if (rc)
return rc;
len = le32_to_cpu(buf[0]);
if (len == 0)
return 0;
list->nodes = kcalloc(len, sizeof(*list->nodes), GFP_KERNEL);
if (!list->nodes)
return -ENOMEM;
data.p = p;
data.other = other;
for (i = 0; i < len; i++) {
data.dst = &list->nodes[i];
rc = avtab_read_item(&p->te_cond_avtab, fp, p, cond_insertf,
&data);
if (rc) {
kfree(list->nodes);
list->nodes = NULL;
return rc;
}
}
list->len = len;
return 0;
}
static int expr_node_isvalid(struct policydb *p, struct cond_expr_node *expr)
{
if (expr->expr_type <= 0 || expr->expr_type > COND_LAST) {
pr_err("SELinux: conditional expressions uses unknown operator.\n");
return 0;
}
if (expr->boolean > p->p_bools.nprim) {
pr_err("SELinux: conditional expressions uses unknown bool.\n");
return 0;
}
return 1;
}
static int cond_read_node(struct policydb *p, struct cond_node *node, void *fp)
{
__le32 buf[2];
u32 i, len;
int rc;
rc = next_entry(buf, fp, sizeof(u32) * 2);
if (rc)
return rc;
node->cur_state = le32_to_cpu(buf[0]);
/* expr */
len = le32_to_cpu(buf[1]);
node->expr.nodes = kcalloc(len, sizeof(*node->expr.nodes), GFP_KERNEL);
if (!node->expr.nodes)
return -ENOMEM;
node->expr.len = len;
for (i = 0; i < len; i++) {
struct cond_expr_node *expr = &node->expr.nodes[i];
rc = next_entry(buf, fp, sizeof(u32) * 2);
if (rc)
return rc;
expr->expr_type = le32_to_cpu(buf[0]);
expr->boolean = le32_to_cpu(buf[1]);
if (!expr_node_isvalid(p, expr))
return -EINVAL;
}
rc = cond_read_av_list(p, fp, &node->true_list, NULL);
if (rc)
return rc;
return cond_read_av_list(p, fp, &node->false_list, &node->true_list);
}
int cond_read_list(struct policydb *p, void *fp)
{
__le32 buf[1];
u32 i, len;
int rc;
rc = next_entry(buf, fp, sizeof(buf));
if (rc)
return rc;
len = le32_to_cpu(buf[0]);
p->cond_list = kcalloc(len, sizeof(*p->cond_list), GFP_KERNEL);
if (!p->cond_list)
return -ENOMEM;
rc = avtab_alloc(&(p->te_cond_avtab), p->te_avtab.nel);
if (rc)
goto err;
p->cond_list_len = len;
for (i = 0; i < len; i++) {
rc = cond_read_node(p, &p->cond_list[i], fp);
if (rc)
goto err;
}
return 0;
err:
cond_list_destroy(p);
return rc;
}
int cond_write_bool(void *vkey, void *datum, void *ptr)
{
char *key = vkey;
struct cond_bool_datum *booldatum = datum;
struct policy_data *pd = ptr;
void *fp = pd->fp;
__le32 buf[3];
u32 len;
int rc;
len = strlen(key);
buf[0] = cpu_to_le32(booldatum->value);
buf[1] = cpu_to_le32(booldatum->state);
buf[2] = cpu_to_le32(len);
rc = put_entry(buf, sizeof(u32), 3, fp);
if (rc)
return rc;
rc = put_entry(key, 1, len, fp);
if (rc)
return rc;
return 0;
}
/*
* cond_write_cond_av_list doesn't write out the av_list nodes.
* Instead it writes out the key/value pairs from the avtab. This
* is necessary because there is no way to uniquely identifying rules
* in the avtab so it is not possible to associate individual rules
* in the avtab with a conditional without saving them as part of
* the conditional. This means that the avtab with the conditional
* rules will not be saved but will be rebuilt on policy load.
*/
static int cond_write_av_list(struct policydb *p, struct cond_av_list *list,
struct policy_file *fp)
{
__le32 buf[1];
u32 i;
int rc;
buf[0] = cpu_to_le32(list->len);
rc = put_entry(buf, sizeof(u32), 1, fp);
if (rc)
return rc;
for (i = 0; i < list->len; i++) {
rc = avtab_write_item(p, list->nodes[i], fp);
if (rc)
return rc;
}
return 0;
}
static int cond_write_node(struct policydb *p, struct cond_node *node,
struct policy_file *fp)
{
__le32 buf[2];
int rc;
u32 i;
buf[0] = cpu_to_le32(node->cur_state);
rc = put_entry(buf, sizeof(u32), 1, fp);
if (rc)
return rc;
buf[0] = cpu_to_le32(node->expr.len);
rc = put_entry(buf, sizeof(u32), 1, fp);
if (rc)
return rc;
for (i = 0; i < node->expr.len; i++) {
buf[0] = cpu_to_le32(node->expr.nodes[i].expr_type);
buf[1] = cpu_to_le32(node->expr.nodes[i].boolean);
rc = put_entry(buf, sizeof(u32), 2, fp);
if (rc)
return rc;
}
rc = cond_write_av_list(p, &node->true_list, fp);
if (rc)
return rc;
rc = cond_write_av_list(p, &node->false_list, fp);
if (rc)
return rc;
return 0;
}
int cond_write_list(struct policydb *p, void *fp)
{
u32 i;
__le32 buf[1];
int rc;
buf[0] = cpu_to_le32(p->cond_list_len);
rc = put_entry(buf, sizeof(u32), 1, fp);
if (rc)
return rc;
for (i = 0; i < p->cond_list_len; i++) {
rc = cond_write_node(p, &p->cond_list[i], fp);
if (rc)
return rc;
}
return 0;
}
void cond_compute_xperms(struct avtab *ctab, struct avtab_key *key,
struct extended_perms_decision *xpermd)
{
struct avtab_node *node;
if (!ctab || !key || !xpermd)
return;
for (node = avtab_search_node(ctab, key); node;
node = avtab_search_node_next(node, key->specified)) {
if (node->key.specified & AVTAB_ENABLED)
services_compute_xperms_decision(xpermd, node);
}
}
/* Determine whether additional permissions are granted by the conditional
* av table, and if so, add them to the result
*/
void cond_compute_av(struct avtab *ctab, struct avtab_key *key,
struct av_decision *avd, struct extended_perms *xperms)
{
struct avtab_node *node;
if (!ctab || !key || !avd)
return;
for (node = avtab_search_node(ctab, key); node;
node = avtab_search_node_next(node, key->specified)) {
if ((u16)(AVTAB_ALLOWED | AVTAB_ENABLED) ==
(node->key.specified & (AVTAB_ALLOWED | AVTAB_ENABLED)))
avd->allowed |= node->datum.u.data;
if ((u16)(AVTAB_AUDITDENY | AVTAB_ENABLED) ==
(node->key.specified & (AVTAB_AUDITDENY | AVTAB_ENABLED)))
/* Since a '0' in an auditdeny mask represents a
* permission we do NOT want to audit (dontaudit), we use
* the '&' operand to ensure that all '0's in the mask
* are retained (much unlike the allow and auditallow cases).
*/
avd->auditdeny &= node->datum.u.data;
if ((u16)(AVTAB_AUDITALLOW | AVTAB_ENABLED) ==
(node->key.specified & (AVTAB_AUDITALLOW | AVTAB_ENABLED)))
avd->auditallow |= node->datum.u.data;
if (xperms && (node->key.specified & AVTAB_ENABLED) &&
(node->key.specified & AVTAB_XPERMS))
services_compute_xperms_drivers(xperms, node);
}
}
static int cond_dup_av_list(struct cond_av_list *new,
const struct cond_av_list *orig,
struct avtab *avtab)
{
u32 i;
memset(new, 0, sizeof(*new));
new->nodes = kcalloc(orig->len, sizeof(*new->nodes), GFP_KERNEL);
if (!new->nodes)
return -ENOMEM;
for (i = 0; i < orig->len; i++) {
new->nodes[i] = avtab_insert_nonunique(
avtab, &orig->nodes[i]->key, &orig->nodes[i]->datum);
if (!new->nodes[i])
return -ENOMEM;
new->len++;
}
return 0;
}
static int duplicate_policydb_cond_list(struct policydb *newp,
const struct policydb *origp)
{
int rc;
u32 i;
rc = avtab_alloc_dup(&newp->te_cond_avtab, &origp->te_cond_avtab);
if (rc)
return rc;
newp->cond_list_len = 0;
newp->cond_list = kcalloc(origp->cond_list_len,
sizeof(*newp->cond_list), GFP_KERNEL);
if (!newp->cond_list)
goto error;
for (i = 0; i < origp->cond_list_len; i++) {
struct cond_node *newn = &newp->cond_list[i];
const struct cond_node *orign = &origp->cond_list[i];
newp->cond_list_len++;
newn->cur_state = orign->cur_state;
newn->expr.nodes =
kmemdup(orign->expr.nodes,
orign->expr.len * sizeof(*orign->expr.nodes),
GFP_KERNEL);
if (!newn->expr.nodes)
goto error;
newn->expr.len = orign->expr.len;
rc = cond_dup_av_list(&newn->true_list, &orign->true_list,
&newp->te_cond_avtab);
if (rc)
goto error;
rc = cond_dup_av_list(&newn->false_list, &orign->false_list,
&newp->te_cond_avtab);
if (rc)
goto error;
}
return 0;
error:
avtab_destroy(&newp->te_cond_avtab);
cond_list_destroy(newp);
return -ENOMEM;
}
static int cond_bools_destroy(void *key, void *datum, void *args)
{
/* key was not copied so no need to free here */
kfree(datum);
return 0;
}
static int cond_bools_copy(struct hashtab_node *new,
const struct hashtab_node *orig, void *args)
{
struct cond_bool_datum *datum;
datum = kmemdup(orig->datum, sizeof(struct cond_bool_datum),
GFP_KERNEL);
if (!datum)
return -ENOMEM;
new->key = orig->key; /* No need to copy, never modified */
new->datum = datum;
return 0;
}
static int cond_bools_index(void *key, void *datum, void *args)
{
struct cond_bool_datum *booldatum, **cond_bool_array;
booldatum = datum;
cond_bool_array = args;
cond_bool_array[booldatum->value - 1] = booldatum;
return 0;
}
static int duplicate_policydb_bools(struct policydb *newdb,
const struct policydb *orig)
{
struct cond_bool_datum **cond_bool_array;
int rc;
cond_bool_array = kmalloc_array(orig->p_bools.nprim,
sizeof(*orig->bool_val_to_struct),
GFP_KERNEL);
if (!cond_bool_array)
return -ENOMEM;
rc = hashtab_duplicate(&newdb->p_bools.table, &orig->p_bools.table,
cond_bools_copy, cond_bools_destroy, NULL);
if (rc) {
kfree(cond_bool_array);
return -ENOMEM;
}
hashtab_map(&newdb->p_bools.table, cond_bools_index, cond_bool_array);
newdb->bool_val_to_struct = cond_bool_array;
newdb->p_bools.nprim = orig->p_bools.nprim;
return 0;
}
void cond_policydb_destroy_dup(struct policydb *p)
{
hashtab_map(&p->p_bools.table, cond_bools_destroy, NULL);
hashtab_destroy(&p->p_bools.table);
cond_policydb_destroy(p);
}
int cond_policydb_dup(struct policydb *new, const struct policydb *orig)
{
cond_policydb_init(new);
if (duplicate_policydb_bools(new, orig))
return -ENOMEM;
if (duplicate_policydb_cond_list(new, orig)) {
cond_policydb_destroy_dup(new);
return -ENOMEM;
}
return 0;
}
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