/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Implementation of the access vector table type.
*
* Author : Stephen Smalley, <[email protected]>
*/
/* Updated: Frank Mayer <[email protected]> and
* Karl MacMillan <[email protected]>
* Added conditional policy language extensions
* Copyright (C) 2003 Tresys Technology, LLC
*
* Updated: Yuichi Nakamura <[email protected]>
* Tuned number of hash slots for avtab to reduce memory usage
*/
#include <linux/bitops.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include "avtab.h"
#include "policydb.h"
static struct kmem_cache *avtab_node_cachep __ro_after_init;
static struct kmem_cache *avtab_xperms_cachep __ro_after_init;
/* Based on MurmurHash3, written by Austin Appleby and placed in the
* public domain.
*/
static inline u32 avtab_hash(const struct avtab_key *keyp, u32 mask)
{
static const u32 c1 = 0xcc9e2d51;
static const u32 c2 = 0x1b873593;
static const u32 r1 = 15;
static const u32 r2 = 13;
static const u32 m = 5;
static const u32 n = 0xe6546b64;
u32 hash = 0;
#define mix(input) \
do { \
u32 v = input; \
v *= c1; \
v = (v << r1) | (v >> (32 - r1)); \
v *= c2; \
hash ^= v; \
hash = (hash << r2) | (hash >> (32 - r2)); \
hash = hash * m + n; \
} while (0)
mix(keyp->target_class);
mix(keyp->target_type);
mix(keyp->source_type);
#undef mix
hash ^= hash >> 16;
hash *= 0x85ebca6b;
hash ^= hash >> 13;
hash *= 0xc2b2ae35;
hash ^= hash >> 16;
return hash & mask;
}
static struct avtab_node *avtab_insert_node(struct avtab *h,
struct avtab_node **dst,
const struct avtab_key *key,
const struct avtab_datum *datum)
{
struct avtab_node *newnode;
struct avtab_extended_perms *xperms;
newnode = kmem_cache_zalloc(avtab_node_cachep, GFP_KERNEL);
if (newnode == NULL)
return NULL;
newnode->key = *key;
if (key->specified & AVTAB_XPERMS) {
xperms = kmem_cache_zalloc(avtab_xperms_cachep, GFP_KERNEL);
if (xperms == NULL) {
kmem_cache_free(avtab_node_cachep, newnode);
return NULL;
}
*xperms = *(datum->u.xperms);
newnode->datum.u.xperms = xperms;
} else {
newnode->datum.u.data = datum->u.data;
}
newnode->next = *dst;
*dst = newnode;
h->nel++;
return newnode;
}
static int avtab_node_cmp(const struct avtab_key *key1,
const struct avtab_key *key2)
{
u16 specified = key1->specified & ~(AVTAB_ENABLED | AVTAB_ENABLED_OLD);
if (key1->source_type == key2->source_type &&
key1->target_type == key2->target_type &&
key1->target_class == key2->target_class &&
(specified & key2->specified))
return 0;
if (key1->source_type < key2->source_type)
return -1;
if (key1->source_type == key2->source_type &&
key1->target_type < key2->target_type)
return -1;
if (key1->source_type == key2->source_type &&
key1->target_type == key2->target_type &&
key1->target_class < key2->target_class)
return -1;
return 1;
}
static int avtab_insert(struct avtab *h, const struct avtab_key *key,
const struct avtab_datum *datum)
{
u32 hvalue;
struct avtab_node *prev, *cur, *newnode;
int cmp;
if (!h || !h->nslot || h->nel == U32_MAX)
return -EINVAL;
hvalue = avtab_hash(key, h->mask);
for (prev = NULL, cur = h->htable[hvalue]; cur;
prev = cur, cur = cur->next) {
cmp = avtab_node_cmp(key, &cur->key);
/* extended perms may not be unique */
if (cmp == 0 && !(key->specified & AVTAB_XPERMS))
return -EEXIST;
if (cmp <= 0)
break;
}
newnode = avtab_insert_node(h, prev ? &prev->next : &h->htable[hvalue],
key, datum);
if (!newnode)
return -ENOMEM;
return 0;
}
/* Unlike avtab_insert(), this function allow multiple insertions of the same
* key/specified mask into the table, as needed by the conditional avtab.
* It also returns a pointer to the node inserted.
*/
struct avtab_node *avtab_insert_nonunique(struct avtab *h,
const struct avtab_key *key,
const struct avtab_datum *datum)
{
u32 hvalue;
struct avtab_node *prev, *cur;
int cmp;
if (!h || !h->nslot || h->nel == U32_MAX)
return NULL;
hvalue = avtab_hash(key, h->mask);
for (prev = NULL, cur = h->htable[hvalue]; cur;
prev = cur, cur = cur->next) {
cmp = avtab_node_cmp(key, &cur->key);
if (cmp <= 0)
break;
}
return avtab_insert_node(h, prev ? &prev->next : &h->htable[hvalue],
key, datum);
}
/* This search function returns a node pointer, and can be used in
* conjunction with avtab_search_next_node()
*/
struct avtab_node *avtab_search_node(struct avtab *h,
const struct avtab_key *key)
{
u32 hvalue;
struct avtab_node *cur;
int cmp;
if (!h || !h->nslot)
return NULL;
hvalue = avtab_hash(key, h->mask);
for (cur = h->htable[hvalue]; cur; cur = cur->next) {
cmp = avtab_node_cmp(key, &cur->key);
if (cmp == 0)
return cur;
if (cmp < 0)
break;
}
return NULL;
}
struct avtab_node *avtab_search_node_next(struct avtab_node *node,
u16 specified)
{
struct avtab_key tmp_key;
struct avtab_node *cur;
int cmp;
if (!node)
return NULL;
tmp_key = node->key;
tmp_key.specified = specified;
for (cur = node->next; cur; cur = cur->next) {
cmp = avtab_node_cmp(&tmp_key, &cur->key);
if (cmp == 0)
return cur;
if (cmp < 0)
break;
}
return NULL;
}
void avtab_destroy(struct avtab *h)
{
u32 i;
struct avtab_node *cur, *temp;
if (!h)
return;
for (i = 0; i < h->nslot; i++) {
cur = h->htable[i];
while (cur) {
temp = cur;
cur = cur->next;
if (temp->key.specified & AVTAB_XPERMS)
kmem_cache_free(avtab_xperms_cachep,
temp->datum.u.xperms);
kmem_cache_free(avtab_node_cachep, temp);
}
}
kvfree(h->htable);
h->htable = NULL;
h->nel = 0;
h->nslot = 0;
h->mask = 0;
}
void avtab_init(struct avtab *h)
{
h->htable = NULL;
h->nel = 0;
h->nslot = 0;
h->mask = 0;
}
static int avtab_alloc_common(struct avtab *h, u32 nslot)
{
if (!nslot)
return 0;
h->htable = kvcalloc(nslot, sizeof(void *), GFP_KERNEL);
if (!h->htable)
return -ENOMEM;
h->nslot = nslot;
h->mask = nslot - 1;
return 0;
}
int avtab_alloc(struct avtab *h, u32 nrules)
{
int rc;
u32 nslot = 0;
if (nrules != 0) {
nslot = nrules > 3 ? rounddown_pow_of_two(nrules / 2) : 2;
if (nslot > MAX_AVTAB_HASH_BUCKETS)
nslot = MAX_AVTAB_HASH_BUCKETS;
rc = avtab_alloc_common(h, nslot);
if (rc)
return rc;
}
pr_debug("SELinux: %d avtab hash slots, %d rules.\n", nslot, nrules);
return 0;
}
int avtab_alloc_dup(struct avtab *new, const struct avtab *orig)
{
return avtab_alloc_common(new, orig->nslot);
}
#ifdef CONFIG_SECURITY_SELINUX_DEBUG
void avtab_hash_eval(struct avtab *h, const char *tag)
{
u32 i, chain_len, slots_used, max_chain_len;
unsigned long long chain2_len_sum;
struct avtab_node *cur;
slots_used = 0;
max_chain_len = 0;
chain2_len_sum = 0;
for (i = 0; i < h->nslot; i++) {
cur = h->htable[i];
if (cur) {
slots_used++;
chain_len = 0;
while (cur) {
chain_len++;
cur = cur->next;
}
if (chain_len > max_chain_len)
max_chain_len = chain_len;
chain2_len_sum +=
(unsigned long long)chain_len * chain_len;
}
}
pr_debug("SELinux: %s: %d entries and %d/%d buckets used, "
"longest chain length %d, sum of chain length^2 %llu\n",
tag, h->nel, slots_used, h->nslot, max_chain_len,
chain2_len_sum);
}
#endif /* CONFIG_SECURITY_SELINUX_DEBUG */
/* clang-format off */
static const uint16_t spec_order[] = {
AVTAB_ALLOWED,
AVTAB_AUDITDENY,
AVTAB_AUDITALLOW,
AVTAB_TRANSITION,
AVTAB_CHANGE,
AVTAB_MEMBER,
AVTAB_XPERMS_ALLOWED,
AVTAB_XPERMS_AUDITALLOW,
AVTAB_XPERMS_DONTAUDIT
};
/* clang-format on */
int avtab_read_item(struct avtab *a, void *fp, struct policydb *pol,
int (*insertf)(struct avtab *a, const struct avtab_key *k,
const struct avtab_datum *d, void *p),
void *p)
{
__le16 buf16[4];
u16 enabled;
u32 items, items2, val, i;
struct avtab_key key;
struct avtab_datum datum;
struct avtab_extended_perms xperms;
__le32 buf32[ARRAY_SIZE(xperms.perms.p)];
int rc;
unsigned int set, vers = pol->policyvers;
memset(&key, 0, sizeof(struct avtab_key));
memset(&datum, 0, sizeof(struct avtab_datum));
if (vers < POLICYDB_VERSION_AVTAB) {
rc = next_entry(buf32, fp, sizeof(u32));
if (rc) {
pr_err("SELinux: avtab: truncated entry\n");
return rc;
}
items2 = le32_to_cpu(buf32[0]);
if (items2 > ARRAY_SIZE(buf32)) {
pr_err("SELinux: avtab: entry overflow\n");
return -EINVAL;
}
rc = next_entry(buf32, fp, sizeof(u32) * items2);
if (rc) {
pr_err("SELinux: avtab: truncated entry\n");
return rc;
}
items = 0;
val = le32_to_cpu(buf32[items++]);
key.source_type = (u16)val;
if (key.source_type != val) {
pr_err("SELinux: avtab: truncated source type\n");
return -EINVAL;
}
val = le32_to_cpu(buf32[items++]);
key.target_type = (u16)val;
if (key.target_type != val) {
pr_err("SELinux: avtab: truncated target type\n");
return -EINVAL;
}
val = le32_to_cpu(buf32[items++]);
key.target_class = (u16)val;
if (key.target_class != val) {
pr_err("SELinux: avtab: truncated target class\n");
return -EINVAL;
}
val = le32_to_cpu(buf32[items++]);
enabled = (val & AVTAB_ENABLED_OLD) ? AVTAB_ENABLED : 0;
if (!(val & (AVTAB_AV | AVTAB_TYPE))) {
pr_err("SELinux: avtab: null entry\n");
return -EINVAL;
}
if ((val & AVTAB_AV) && (val & AVTAB_TYPE)) {
pr_err("SELinux: avtab: entry has both access vectors and types\n");
return -EINVAL;
}
if (val & AVTAB_XPERMS) {
pr_err("SELinux: avtab: entry has extended permissions\n");
return -EINVAL;
}
for (i = 0; i < ARRAY_SIZE(spec_order); i++) {
if (val & spec_order[i]) {
key.specified = spec_order[i] | enabled;
datum.u.data = le32_to_cpu(buf32[items++]);
rc = insertf(a, &key, &datum, p);
if (rc)
return rc;
}
}
if (items != items2) {
pr_err("SELinux: avtab: entry only had %d items, expected %d\n",
items2, items);
return -EINVAL;
}
return 0;
}
rc = next_entry(buf16, fp, sizeof(u16) * 4);
if (rc) {
pr_err("SELinux: avtab: truncated entry\n");
return rc;
}
items = 0;
key.source_type = le16_to_cpu(buf16[items++]);
key.target_type = le16_to_cpu(buf16[items++]);
key.target_class = le16_to_cpu(buf16[items++]);
key.specified = le16_to_cpu(buf16[items++]);
if (!policydb_type_isvalid(pol, key.source_type) ||
!policydb_type_isvalid(pol, key.target_type) ||
!policydb_class_isvalid(pol, key.target_class)) {
pr_err("SELinux: avtab: invalid type or class\n");
return -EINVAL;
}
set = hweight16(key.specified & (AVTAB_XPERMS | AVTAB_TYPE | AVTAB_AV));
if (!set || set > 1) {
pr_err("SELinux: avtab: more than one specifier\n");
return -EINVAL;
}
if ((vers < POLICYDB_VERSION_XPERMS_IOCTL) &&
(key.specified & AVTAB_XPERMS)) {
pr_err("SELinux: avtab: policy version %u does not "
"support extended permissions rules and one "
"was specified\n",
vers);
return -EINVAL;
} else if (key.specified & AVTAB_XPERMS) {
memset(&xperms, 0, sizeof(struct avtab_extended_perms));
rc = next_entry(&xperms.specified, fp, sizeof(u8));
if (rc) {
pr_err("SELinux: avtab: truncated entry\n");
return rc;
}
rc = next_entry(&xperms.driver, fp, sizeof(u8));
if (rc) {
pr_err("SELinux: avtab: truncated entry\n");
return rc;
}
rc = next_entry(buf32, fp,
sizeof(u32) * ARRAY_SIZE(xperms.perms.p));
if (rc) {
pr_err("SELinux: avtab: truncated entry\n");
return rc;
}
for (i = 0; i < ARRAY_SIZE(xperms.perms.p); i++)
xperms.perms.p[i] = le32_to_cpu(buf32[i]);
datum.u.xperms = &xperms;
} else {
rc = next_entry(buf32, fp, sizeof(u32));
if (rc) {
pr_err("SELinux: avtab: truncated entry\n");
return rc;
}
datum.u.data = le32_to_cpu(*buf32);
}
if ((key.specified & AVTAB_TYPE) &&
!policydb_type_isvalid(pol, datum.u.data)) {
pr_err("SELinux: avtab: invalid type\n");
return -EINVAL;
}
return insertf(a, &key, &datum, p);
}
static int avtab_insertf(struct avtab *a, const struct avtab_key *k,
const struct avtab_datum *d, void *p)
{
return avtab_insert(a, k, d);
}
int avtab_read(struct avtab *a, void *fp, struct policydb *pol)
{
int rc;
__le32 buf[1];
u32 nel, i;
rc = next_entry(buf, fp, sizeof(u32));
if (rc < 0) {
pr_err("SELinux: avtab: truncated table\n");
goto bad;
}
nel = le32_to_cpu(buf[0]);
if (!nel) {
pr_err("SELinux: avtab: table is empty\n");
rc = -EINVAL;
goto bad;
}
rc = avtab_alloc(a, nel);
if (rc)
goto bad;
for (i = 0; i < nel; i++) {
rc = avtab_read_item(a, fp, pol, avtab_insertf, NULL);
if (rc) {
if (rc == -ENOMEM)
pr_err("SELinux: avtab: out of memory\n");
else if (rc == -EEXIST)
pr_err("SELinux: avtab: duplicate entry\n");
goto bad;
}
}
rc = 0;
out:
return rc;
bad:
avtab_destroy(a);
goto out;
}
int avtab_write_item(struct policydb *p, const struct avtab_node *cur, void *fp)
{
__le16 buf16[4];
__le32 buf32[ARRAY_SIZE(cur->datum.u.xperms->perms.p)];
int rc;
unsigned int i;
buf16[0] = cpu_to_le16(cur->key.source_type);
buf16[1] = cpu_to_le16(cur->key.target_type);
buf16[2] = cpu_to_le16(cur->key.target_class);
buf16[3] = cpu_to_le16(cur->key.specified);
rc = put_entry(buf16, sizeof(u16), 4, fp);
if (rc)
return rc;
if (cur->key.specified & AVTAB_XPERMS) {
rc = put_entry(&cur->datum.u.xperms->specified, sizeof(u8), 1,
fp);
if (rc)
return rc;
rc = put_entry(&cur->datum.u.xperms->driver, sizeof(u8), 1, fp);
if (rc)
return rc;
for (i = 0; i < ARRAY_SIZE(cur->datum.u.xperms->perms.p); i++)
buf32[i] = cpu_to_le32(cur->datum.u.xperms->perms.p[i]);
rc = put_entry(buf32, sizeof(u32),
ARRAY_SIZE(cur->datum.u.xperms->perms.p), fp);
} else {
buf32[0] = cpu_to_le32(cur->datum.u.data);
rc = put_entry(buf32, sizeof(u32), 1, fp);
}
if (rc)
return rc;
return 0;
}
int avtab_write(struct policydb *p, struct avtab *a, void *fp)
{
u32 i;
int rc = 0;
struct avtab_node *cur;
__le32 buf[1];
buf[0] = cpu_to_le32(a->nel);
rc = put_entry(buf, sizeof(u32), 1, fp);
if (rc)
return rc;
for (i = 0; i < a->nslot; i++) {
for (cur = a->htable[i]; cur; cur = cur->next) {
rc = avtab_write_item(p, cur, fp);
if (rc)
return rc;
}
}
return rc;
}
void __init avtab_cache_init(void)
{
avtab_node_cachep = KMEM_CACHE(avtab_node, SLAB_PANIC);
avtab_xperms_cachep = KMEM_CACHE(avtab_extended_perms, SLAB_PANIC);
}
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