mirror of
https://github.com/SELinuxProject/selinux
synced 2024-12-28 08:52:05 +00:00
libsepol: add a function to optimize kernel policy
Add sepol_policydb_optimize(), which checks a kernel policy for
redundant rules (i.e. those that are covered by an existing more general
rule) and removes them.
Results on Fedora 29 policy:
WITHOUT OPTIMIZATION:
# time semodule -B
real 0m21,280s
user 0m18,636s
sys 0m2,525s
$ wc -c /sys/fs/selinux/policy
8692158 /sys/fs/selinux/policy
$ seinfo (edited)
Allow: 113159
Dontaudit: 10297
Total: 123156
WITH OPTIMIZATION ENABLED:
# time semodule -B
real 0m22,825s
user 0m20,178s
sys 0m2,520s
$ wc -c /sys/fs/selinux/policy
8096158 /sys/fs/selinux/policy
$ seinfo (edited)
Allow: 66334
Dontaudit: 7480
Total: 73814
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
This commit is contained in:
Ondrej Mosnacek
James Carter
parent
84b8f30606
commit
b8213acff8
@ -100,6 +100,11 @@ extern int sepol_policydb_set_handle_unknown(sepol_policydb_t * p,
|
||||
extern int sepol_policydb_set_target_platform(sepol_policydb_t * p,
|
||||
int target_platform);
|
||||
|
||||
/*
|
||||
* Optimize the policy by removing redundant rules.
|
||||
*/
|
||||
extern int sepol_policydb_optimize(sepol_policydb_t * p);
|
||||
|
||||
/*
|
||||
* Read a policydb from a policy file.
|
||||
* This automatically sets the type and version based on the
|
||||
|
||||
@ -636,6 +636,8 @@ extern int policydb_user_cache(hashtab_key_t key,
|
||||
|
||||
extern int policydb_reindex_users(policydb_t * p);
|
||||
|
||||
extern int policydb_optimize(policydb_t * p);
|
||||
|
||||
extern void policydb_destroy(policydb_t * p);
|
||||
|
||||
extern int policydb_load_isids(policydb_t * p, sidtab_t * s);
|
||||
|
||||
@ -59,3 +59,8 @@ LIBSEPOL_1.1 {
|
||||
sepol_polcap_getnum;
|
||||
sepol_polcap_getname;
|
||||
} LIBSEPOL_1.0;
|
||||
|
||||
LIBSEPOL_1.2 {
|
||||
global:
|
||||
sepol_optimize_policy;
|
||||
} LIBSEPOL_1.1;
|
||||
|
||||
378
libsepol/src/optimize.c
Normal file
378
libsepol/src/optimize.c
Normal file
@ -0,0 +1,378 @@
|
||||
/*
|
||||
* Author: Ondrej Mosnacek <omosnacek@gmail.com>
|
||||
*
|
||||
* Copyright (C) 2019 Red Hat Inc.
|
||||
*
|
||||
* This library is free software; you can redistribute it and/or
|
||||
* modify it under the terms of the GNU Lesser General Public
|
||||
* License as published by the Free Software Foundation; either
|
||||
* version 2.1 of the License, or (at your option) any later version.
|
||||
*
|
||||
* This library 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
|
||||
* Lesser General Public License for more details.
|
||||
*
|
||||
* You should have received a copy of the GNU Lesser General Public
|
||||
* License along with this library; if not, write to the Free Software
|
||||
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
|
||||
*/
|
||||
|
||||
/*
|
||||
* Binary policy optimization.
|
||||
*
|
||||
* Defines the policydb_optimize() function, which finds and removes
|
||||
* redundant rules from the binary policy to reduce its size and potentially
|
||||
* improve rule matching times. Only rules that are already covered by a
|
||||
* more general rule are removed. The resulting policy is functionally
|
||||
* equivalent to the original one.
|
||||
*/
|
||||
|
||||
#include <sepol/policydb/policydb.h>
|
||||
#include <sepol/policydb/conditional.h>
|
||||
|
||||
/* builds map: type/attribute -> {all attributes that are a superset of it} */
|
||||
static ebitmap_t *build_type_map(const policydb_t *p)
|
||||
{
|
||||
unsigned int i, k;
|
||||
ebitmap_t *map = malloc(p->p_types.nprim * sizeof(ebitmap_t));
|
||||
if (!map)
|
||||
return NULL;
|
||||
|
||||
for (i = 0; i < p->p_types.nprim; i++) {
|
||||
if (p->type_val_to_struct[i] &&
|
||||
p->type_val_to_struct[i]->flavor != TYPE_ATTRIB) {
|
||||
if (ebitmap_cpy(&map[i], &p->type_attr_map[i]))
|
||||
goto err;
|
||||
} else {
|
||||
ebitmap_t *types_i = &p->attr_type_map[i];
|
||||
|
||||
ebitmap_init(&map[i]);
|
||||
for (k = 0; k < p->p_types.nprim; k++) {
|
||||
ebitmap_t *types_k = &p->attr_type_map[k];
|
||||
|
||||
if (ebitmap_contains(types_k, types_i)) {
|
||||
if (ebitmap_set_bit(&map[i], k, 1))
|
||||
goto err;
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
return map;
|
||||
err:
|
||||
for (k = 0; k <= i; k++)
|
||||
ebitmap_destroy(&map[k]);
|
||||
free(map);
|
||||
return NULL;
|
||||
}
|
||||
|
||||
static void destroy_type_map(const policydb_t *p, ebitmap_t *type_map)
|
||||
{
|
||||
unsigned int i;
|
||||
for (i = 0; i < p->p_types.nprim; i++)
|
||||
ebitmap_destroy(&type_map[i]);
|
||||
free(type_map);
|
||||
}
|
||||
|
||||
static int process_xperms(uint32_t *p1, const uint32_t *p2)
|
||||
{
|
||||
size_t i;
|
||||
int ret = 1;
|
||||
|
||||
for (i = 0; i < EXTENDED_PERMS_LEN; i++) {
|
||||
p1[i] &= ~p2[i];
|
||||
if (p1[i] != 0)
|
||||
ret = 0;
|
||||
}
|
||||
return ret;
|
||||
}
|
||||
|
||||
static int process_avtab_datum(uint16_t specified,
|
||||
avtab_datum_t *d1, const avtab_datum_t *d2)
|
||||
{
|
||||
/* inverse logic needed for AUDITDENY rules */
|
||||
if (specified & AVTAB_AUDITDENY)
|
||||
return (d1->data |= ~d2->data) == UINT32_C(0xFFFFFFFF);
|
||||
|
||||
if (specified & AVTAB_AV)
|
||||
return (d1->data &= ~d2->data) == 0;
|
||||
|
||||
if (specified & AVTAB_XPERMS) {
|
||||
avtab_extended_perms_t *x1 = d1->xperms;
|
||||
const avtab_extended_perms_t *x2 = d2->xperms;
|
||||
|
||||
if (x1->specified == AVTAB_XPERMS_IOCTLFUNCTION) {
|
||||
if (x2->specified == AVTAB_XPERMS_IOCTLFUNCTION) {
|
||||
if (x1->driver != x2->driver)
|
||||
return 0;
|
||||
return process_xperms(x1->perms, x2->perms);
|
||||
}
|
||||
if (x2->specified == AVTAB_XPERMS_IOCTLDRIVER)
|
||||
return xperm_test(x1->driver, x2->perms);
|
||||
} else if (x1->specified == AVTAB_XPERMS_IOCTLDRIVER) {
|
||||
if (x2->specified == AVTAB_XPERMS_IOCTLFUNCTION)
|
||||
return 0;
|
||||
|
||||
if (x2->specified == AVTAB_XPERMS_IOCTLDRIVER)
|
||||
return process_xperms(x1->perms, x2->perms);
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
|
||||
/* checks if avtab contains a rule that covers the given rule */
|
||||
static int is_avrule_redundant(avtab_ptr_t entry, avtab_t *tab,
|
||||
const ebitmap_t *type_map)
|
||||
{
|
||||
unsigned int i, k, s_idx, t_idx;
|
||||
ebitmap_node_t *snode, *tnode;
|
||||
avtab_datum_t *d1, *d2;
|
||||
avtab_key_t key;
|
||||
|
||||
/* we only care about AV rules */
|
||||
if (!(entry->key.specified & (AVTAB_AV|AVTAB_XPERMS)))
|
||||
return 0;
|
||||
|
||||
s_idx = entry->key.source_type - 1;
|
||||
t_idx = entry->key.target_type - 1;
|
||||
|
||||
key.target_class = entry->key.target_class;
|
||||
key.specified = entry->key.specified;
|
||||
|
||||
d1 = &entry->datum;
|
||||
|
||||
ebitmap_for_each_positive_bit(&type_map[s_idx], snode, i) {
|
||||
key.source_type = i + 1;
|
||||
|
||||
ebitmap_for_each_positive_bit(&type_map[t_idx], tnode, k) {
|
||||
if (s_idx == i && t_idx == k)
|
||||
continue;
|
||||
|
||||
key.target_type = k + 1;
|
||||
|
||||
d2 = avtab_search(tab, &key);
|
||||
if (!d2)
|
||||
continue;
|
||||
|
||||
if (process_avtab_datum(key.specified, d1, d2))
|
||||
return 1;
|
||||
}
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
|
||||
static int is_type_attr(policydb_t *p, unsigned int id)
|
||||
{
|
||||
return p->type_val_to_struct[id]->flavor == TYPE_ATTRIB;
|
||||
}
|
||||
|
||||
static int is_avrule_with_attr(avtab_ptr_t entry, policydb_t *p)
|
||||
{
|
||||
unsigned int s_idx = entry->key.source_type - 1;
|
||||
unsigned int t_idx = entry->key.target_type - 1;
|
||||
|
||||
return is_type_attr(p, s_idx) || is_type_attr(p, t_idx);
|
||||
}
|
||||
|
||||
/* checks if conditional list contains a rule that covers the given rule */
|
||||
static int is_cond_rule_redundant(avtab_ptr_t e1, cond_av_list_t *list,
|
||||
const ebitmap_t *type_map)
|
||||
{
|
||||
unsigned int s1, t1, c1, k1, s2, t2, c2, k2;
|
||||
|
||||
/* we only care about AV rules */
|
||||
if (!(e1->key.specified & (AVTAB_AV|AVTAB_XPERMS)))
|
||||
return 0;
|
||||
|
||||
s1 = e1->key.source_type - 1;
|
||||
t1 = e1->key.target_type - 1;
|
||||
c1 = e1->key.target_class;
|
||||
k1 = e1->key.specified;
|
||||
|
||||
for (; list; list = list->next) {
|
||||
avtab_ptr_t e2 = list->node;
|
||||
|
||||
s2 = e2->key.source_type - 1;
|
||||
t2 = e2->key.target_type - 1;
|
||||
c2 = e2->key.target_class;
|
||||
k2 = e2->key.specified;
|
||||
|
||||
if (k1 != k2 || c1 != c2)
|
||||
continue;
|
||||
|
||||
if (s1 == s2 && t1 == t2)
|
||||
continue;
|
||||
if (!ebitmap_get_bit(&type_map[s1], s2))
|
||||
continue;
|
||||
if (!ebitmap_get_bit(&type_map[t1], t2))
|
||||
continue;
|
||||
|
||||
if (process_avtab_datum(k1, &e1->datum, &e2->datum))
|
||||
return 1;
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
|
||||
static void optimize_avtab(policydb_t *p, const ebitmap_t *type_map)
|
||||
{
|
||||
avtab_t *tab = &p->te_avtab;
|
||||
unsigned int i;
|
||||
avtab_ptr_t *cur;
|
||||
|
||||
for (i = 0; i < tab->nslot; i++) {
|
||||
cur = &tab->htable[i];
|
||||
while (*cur) {
|
||||
if (is_avrule_redundant(*cur, tab, type_map)) {
|
||||
/* redundant rule -> remove it */
|
||||
avtab_ptr_t tmp = *cur;
|
||||
|
||||
*cur = tmp->next;
|
||||
if (tmp->key.specified & AVTAB_XPERMS)
|
||||
free(tmp->datum.xperms);
|
||||
free(tmp);
|
||||
|
||||
tab->nel--;
|
||||
} else {
|
||||
/* rule not redundant -> move to next rule */
|
||||
cur = &(*cur)->next;
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/* find redundant rules in (*cond) and put them into (*del) */
|
||||
static void optimize_cond_av_list(cond_av_list_t **cond, cond_av_list_t **del,
|
||||
policydb_t *p, const ebitmap_t *type_map)
|
||||
{
|
||||
cond_av_list_t **listp = cond;
|
||||
cond_av_list_t *pcov = NULL;
|
||||
cond_av_list_t **pcov_cur = &pcov;
|
||||
|
||||
/*
|
||||
* Separate out all "potentially covering" rules (src or tgt is an attr)
|
||||
* and move them to the end of the list. This is needed to avoid
|
||||
* polynomial complexity when almost all rules are expanded.
|
||||
*/
|
||||
while (*cond) {
|
||||
if (is_avrule_with_attr((*cond)->node, p)) {
|
||||
cond_av_list_t *tmp = *cond;
|
||||
|
||||
*cond = tmp->next;
|
||||
tmp->next = pcov;
|
||||
pcov = tmp;
|
||||
} else {
|
||||
cond = &(*cond)->next;
|
||||
}
|
||||
}
|
||||
/* link the "potentially covering" rules to the end of the list */
|
||||
*cond = pcov;
|
||||
|
||||
/* now go through the list and find the redundant rules */
|
||||
cond = listp;
|
||||
pcov_cur = &pcov;
|
||||
while (*cond) {
|
||||
/* needed because pcov itself may get deleted */
|
||||
if (*cond == pcov)
|
||||
pcov_cur = cond;
|
||||
/*
|
||||
* First check if covered by an unconditional rule, then also
|
||||
* check if covered by another rule in the same list.
|
||||
*/
|
||||
if (is_avrule_redundant((*cond)->node, &p->te_avtab, type_map) ||
|
||||
is_cond_rule_redundant((*cond)->node, *pcov_cur, type_map)) {
|
||||
cond_av_list_t *tmp = *cond;
|
||||
|
||||
*cond = tmp->next;
|
||||
tmp->next = *del;
|
||||
*del = tmp;
|
||||
} else {
|
||||
cond = &(*cond)->next;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
static void optimize_cond_avtab(policydb_t *p, const ebitmap_t *type_map)
|
||||
{
|
||||
avtab_t *tab = &p->te_cond_avtab;
|
||||
unsigned int i;
|
||||
avtab_ptr_t *cur;
|
||||
cond_node_t **cond;
|
||||
cond_av_list_t **avcond, *del = NULL;
|
||||
|
||||
/* First go through all conditionals and collect redundant rules. */
|
||||
cond = &p->cond_list;
|
||||
while (*cond) {
|
||||
optimize_cond_av_list(&(*cond)->true_list, &del, p, type_map);
|
||||
optimize_cond_av_list(&(*cond)->false_list, &del, p, type_map);
|
||||
/* TODO: maybe also check for rules present in both lists */
|
||||
|
||||
/* nothing left in both lists -> remove the whole conditional */
|
||||
if (!(*cond)->true_list && !(*cond)->false_list) {
|
||||
cond_node_t *cond_tmp = *cond;
|
||||
|
||||
*cond = cond_tmp->next;
|
||||
cond_node_destroy(cond_tmp);
|
||||
free(cond_tmp);
|
||||
} else {
|
||||
cond = &(*cond)->next;
|
||||
}
|
||||
}
|
||||
|
||||
if (!del)
|
||||
return;
|
||||
|
||||
/*
|
||||
* Now go through the whole cond_avtab and remove all rules that are
|
||||
* found in the 'del' list.
|
||||
*/
|
||||
for (i = 0; i < tab->nslot; i++) {
|
||||
cur = &tab->htable[i];
|
||||
while (*cur) {
|
||||
int redundant = 0;
|
||||
avcond = &del;
|
||||
while (*avcond) {
|
||||
if ((*avcond)->node == *cur) {
|
||||
cond_av_list_t *cond_tmp = *avcond;
|
||||
|
||||
*avcond = cond_tmp->next;
|
||||
free(cond_tmp);
|
||||
redundant = 1;
|
||||
break;
|
||||
} else {
|
||||
avcond = &(*avcond)->next;
|
||||
}
|
||||
}
|
||||
if (redundant) {
|
||||
avtab_ptr_t tmp = *cur;
|
||||
|
||||
*cur = tmp->next;
|
||||
if (tmp->key.specified & AVTAB_XPERMS)
|
||||
free(tmp->datum.xperms);
|
||||
free(tmp);
|
||||
|
||||
tab->nel--;
|
||||
} else {
|
||||
cur = &(*cur)->next;
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
int policydb_optimize(policydb_t *p)
|
||||
{
|
||||
ebitmap_t *type_map;
|
||||
|
||||
if (p->policy_type != POLICY_KERN)
|
||||
return -1;
|
||||
|
||||
type_map = build_type_map(p);
|
||||
if (!type_map)
|
||||
return -1;
|
||||
|
||||
optimize_avtab(p, type_map);
|
||||
optimize_cond_avtab(p, type_map);
|
||||
|
||||
destroy_type_map(p, type_map);
|
||||
return 0;
|
||||
}
|
||||
@ -169,6 +169,11 @@ int sepol_policydb_set_target_platform(sepol_policydb_t * sp,
|
||||
return 0;
|
||||
}
|
||||
|
||||
int sepol_policydb_optimize(sepol_policydb_t * p)
|
||||
{
|
||||
return policydb_optimize(&p->p);
|
||||
}
|
||||
|
||||
int sepol_policydb_read(sepol_policydb_t * p, sepol_policy_file_t * pf)
|
||||
{
|
||||
return policydb_read(&p->p, &pf->pf, 0);
|
||||
|
||||
Loading…
Reference in New Issue
Block a user