WSL2-Linux-Kernel/security/selinux/ss/sidtab.c

307 строки
5.8 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Implementation of the SID table type.
*
* Author : Stephen Smalley, <sds@tycho.nsa.gov>
*/
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/errno.h>
#include "flask.h"
#include "security.h"
#include "sidtab.h"
#define SIDTAB_HASH(sid) \
(sid & SIDTAB_HASH_MASK)
int sidtab_init(struct sidtab *s)
{
int i;
s->htable = kmalloc_array(SIDTAB_SIZE, sizeof(*s->htable), GFP_ATOMIC);
if (!s->htable)
return -ENOMEM;
for (i = 0; i < SIDTAB_SIZE; i++)
s->htable[i] = NULL;
s->nel = 0;
s->next_sid = 1;
s->shutdown = 0;
spin_lock_init(&s->lock);
return 0;
}
int sidtab_insert(struct sidtab *s, u32 sid, struct context *context)
{
int hvalue;
struct sidtab_node *prev, *cur, *newnode;
if (!s)
return -ENOMEM;
hvalue = SIDTAB_HASH(sid);
prev = NULL;
cur = s->htable[hvalue];
while (cur && sid > cur->sid) {
prev = cur;
cur = cur->next;
}
if (cur && sid == cur->sid)
return -EEXIST;
newnode = kmalloc(sizeof(*newnode), GFP_ATOMIC);
if (!newnode)
return -ENOMEM;
newnode->sid = sid;
if (context_cpy(&newnode->context, context)) {
kfree(newnode);
return -ENOMEM;
}
if (prev) {
newnode->next = prev->next;
wmb();
prev->next = newnode;
} else {
newnode->next = s->htable[hvalue];
wmb();
s->htable[hvalue] = newnode;
}
s->nel++;
if (sid >= s->next_sid)
s->next_sid = sid + 1;
return 0;
}
static struct context *sidtab_search_core(struct sidtab *s, u32 sid, int force)
{
int hvalue;
struct sidtab_node *cur;
if (!s)
return NULL;
hvalue = SIDTAB_HASH(sid);
cur = s->htable[hvalue];
while (cur && sid > cur->sid)
cur = cur->next;
if (force && cur && sid == cur->sid && cur->context.len)
return &cur->context;
if (!cur || sid != cur->sid || cur->context.len) {
/* Remap invalid SIDs to the unlabeled SID. */
sid = SECINITSID_UNLABELED;
hvalue = SIDTAB_HASH(sid);
cur = s->htable[hvalue];
while (cur && sid > cur->sid)
cur = cur->next;
if (!cur || sid != cur->sid)
return NULL;
}
return &cur->context;
}
struct context *sidtab_search(struct sidtab *s, u32 sid)
{
return sidtab_search_core(s, sid, 0);
}
struct context *sidtab_search_force(struct sidtab *s, u32 sid)
{
return sidtab_search_core(s, sid, 1);
}
int sidtab_map(struct sidtab *s,
int (*apply) (u32 sid,
struct context *context,
void *args),
void *args)
{
int i, rc = 0;
struct sidtab_node *cur;
if (!s)
goto out;
for (i = 0; i < SIDTAB_SIZE; i++) {
cur = s->htable[i];
while (cur) {
rc = apply(cur->sid, &cur->context, args);
if (rc)
goto out;
cur = cur->next;
}
}
out:
return rc;
}
static void sidtab_update_cache(struct sidtab *s, struct sidtab_node *n, int loc)
{
BUG_ON(loc >= SIDTAB_CACHE_LEN);
while (loc > 0) {
s->cache[loc] = s->cache[loc - 1];
loc--;
}
s->cache[0] = n;
}
static inline u32 sidtab_search_context(struct sidtab *s,
struct context *context)
{
int i;
struct sidtab_node *cur;
for (i = 0; i < SIDTAB_SIZE; i++) {
cur = s->htable[i];
while (cur) {
if (context_cmp(&cur->context, context)) {
sidtab_update_cache(s, cur, SIDTAB_CACHE_LEN - 1);
return cur->sid;
}
cur = cur->next;
}
}
return 0;
}
static inline u32 sidtab_search_cache(struct sidtab *s, struct context *context)
{
int i;
struct sidtab_node *node;
for (i = 0; i < SIDTAB_CACHE_LEN; i++) {
node = s->cache[i];
if (unlikely(!node))
return 0;
if (context_cmp(&node->context, context)) {
sidtab_update_cache(s, node, i);
return node->sid;
}
}
return 0;
}
int sidtab_context_to_sid(struct sidtab *s,
struct context *context,
u32 *out_sid)
{
u32 sid;
int ret = 0;
unsigned long flags;
*out_sid = SECSID_NULL;
sid = sidtab_search_cache(s, context);
if (!sid)
sid = sidtab_search_context(s, context);
if (!sid) {
spin_lock_irqsave(&s->lock, flags);
/* Rescan now that we hold the lock. */
sid = sidtab_search_context(s, context);
if (sid)
goto unlock_out;
/* No SID exists for the context. Allocate a new one. */
if (s->next_sid == UINT_MAX || s->shutdown) {
ret = -ENOMEM;
goto unlock_out;
}
sid = s->next_sid++;
if (context->len)
pr_info("SELinux: Context %s is not valid (left unmapped).\n",
context->str);
ret = sidtab_insert(s, sid, context);
if (ret)
s->next_sid--;
unlock_out:
spin_unlock_irqrestore(&s->lock, flags);
}
if (ret)
return ret;
*out_sid = sid;
return 0;
}
void sidtab_hash_eval(struct sidtab *h, char *tag)
{
int i, chain_len, slots_used, max_chain_len;
struct sidtab_node *cur;
slots_used = 0;
max_chain_len = 0;
for (i = 0; i < SIDTAB_SIZE; 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;
}
}
pr_debug("%s: %d entries and %d/%d buckets used, longest "
"chain length %d\n", tag, h->nel, slots_used, SIDTAB_SIZE,
max_chain_len);
}
void sidtab_destroy(struct sidtab *s)
{
int i;
struct sidtab_node *cur, *temp;
if (!s)
return;
for (i = 0; i < SIDTAB_SIZE; i++) {
cur = s->htable[i];
while (cur) {
temp = cur;
cur = cur->next;
context_destroy(&temp->context);
kfree(temp);
}
s->htable[i] = NULL;
}
kfree(s->htable);
s->htable = NULL;
s->nel = 0;
s->next_sid = 1;
}
void sidtab_set(struct sidtab *dst, struct sidtab *src)
{
unsigned long flags;
int i;
spin_lock_irqsave(&src->lock, flags);
dst->htable = src->htable;
dst->nel = src->nel;
dst->next_sid = src->next_sid;
dst->shutdown = 0;
for (i = 0; i < SIDTAB_CACHE_LEN; i++)
dst->cache[i] = NULL;
spin_unlock_irqrestore(&src->lock, flags);
}
void sidtab_shutdown(struct sidtab *s)
{
unsigned long flags;
spin_lock_irqsave(&s->lock, flags);
s->shutdown = 1;
spin_unlock_irqrestore(&s->lock, flags);
}