// SPDX-License-Identifier: GPL-2.0-or-later
#include <crypto/hash.h>
#include <linux/cpu.h>
#include <linux/kref.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/percpu.h>
#include <linux/workqueue.h>
#include <net/tcp.h>
static size_t __scratch_size;
struct sigpool_scratch {
local_lock_t bh_lock;
void __rcu *pad;
};
static DEFINE_PER_CPU(struct sigpool_scratch, sigpool_scratch) = {
.bh_lock = INIT_LOCAL_LOCK(bh_lock),
};
struct sigpool_entry {
struct crypto_ahash *hash;
const char *alg;
struct kref kref;
uint16_t needs_key:1,
reserved:15;
};
#define CPOOL_SIZE (PAGE_SIZE / sizeof(struct sigpool_entry))
static struct sigpool_entry cpool[CPOOL_SIZE];
static unsigned int cpool_populated;
static DEFINE_MUTEX(cpool_mutex);
/* Slow-path */
struct scratches_to_free {
struct rcu_head rcu;
unsigned int cnt;
void *scratches[];
};
static void free_old_scratches(struct rcu_head *head)
{
struct scratches_to_free *stf;
stf = container_of(head, struct scratches_to_free, rcu);
while (stf->cnt--)
kfree(stf->scratches[stf->cnt]);
kfree(stf);
}
/**
* sigpool_reserve_scratch - re-allocates scratch buffer, slow-path
* @size: request size for the scratch/temp buffer
*/
static int sigpool_reserve_scratch(size_t size)
{
struct scratches_to_free *stf;
size_t stf_sz = struct_size(stf, scratches, num_possible_cpus());
int cpu, err = 0;
lockdep_assert_held(&cpool_mutex);
if (__scratch_size >= size)
return 0;
stf = kmalloc(stf_sz, GFP_KERNEL);
if (!stf)
return -ENOMEM;
stf->cnt = 0;
size = max(size, __scratch_size);
cpus_read_lock();
for_each_possible_cpu(cpu) {
void *scratch, *old_scratch;
scratch = kmalloc_node(size, GFP_KERNEL, cpu_to_node(cpu));
if (!scratch) {
err = -ENOMEM;
break;
}
old_scratch = rcu_replace_pointer(per_cpu(sigpool_scratch.pad, cpu),
scratch, lockdep_is_held(&cpool_mutex));
if (!cpu_online(cpu) || !old_scratch) {
kfree(old_scratch);
continue;
}
stf->scratches[stf->cnt++] = old_scratch;
}
cpus_read_unlock();
if (!err)
__scratch_size = size;
call_rcu(&stf->rcu, free_old_scratches);
return err;
}
static void sigpool_scratch_free(void)
{
int cpu;
for_each_possible_cpu(cpu)
kfree(rcu_replace_pointer(per_cpu(sigpool_scratch.pad, cpu),
NULL, lockdep_is_held(&cpool_mutex)));
__scratch_size = 0;
}
static int __cpool_try_clone(struct crypto_ahash *hash)
{
struct crypto_ahash *tmp;
tmp = crypto_clone_ahash(hash);
if (IS_ERR(tmp))
return PTR_ERR(tmp);
crypto_free_ahash(tmp);
return 0;
}
static int __cpool_alloc_ahash(struct sigpool_entry *e, const char *alg)
{
struct crypto_ahash *cpu0_hash;
int ret;
e->alg = kstrdup(alg, GFP_KERNEL);
if (!e->alg)
return -ENOMEM;
cpu0_hash = crypto_alloc_ahash(alg, 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(cpu0_hash)) {
ret = PTR_ERR(cpu0_hash);
goto out_free_alg;
}
e->needs_key = crypto_ahash_get_flags(cpu0_hash) & CRYPTO_TFM_NEED_KEY;
ret = __cpool_try_clone(cpu0_hash);
if (ret)
goto out_free_cpu0_hash;
e->hash = cpu0_hash;
kref_init(&e->kref);
return 0;
out_free_cpu0_hash:
crypto_free_ahash(cpu0_hash);
out_free_alg:
kfree(e->alg);
e->alg = NULL;
return ret;
}
/**
* tcp_sigpool_alloc_ahash - allocates pool for ahash requests
* @alg: name of async hash algorithm
* @scratch_size: reserve a tcp_sigpool::scratch buffer of this size
*/
int tcp_sigpool_alloc_ahash(const char *alg, size_t scratch_size)
{
int i, ret;
/* slow-path */
mutex_lock(&cpool_mutex);
ret = sigpool_reserve_scratch(scratch_size);
if (ret)
goto out;
for (i = 0; i < cpool_populated; i++) {
if (!cpool[i].alg)
continue;
if (strcmp(cpool[i].alg, alg))
continue;
/* pairs with tcp_sigpool_release() */
if (!kref_get_unless_zero(&cpool[i].kref))
kref_init(&cpool[i].kref);
ret = i;
goto out;
}
for (i = 0; i < cpool_populated; i++) {
if (!cpool[i].alg)
break;
}
if (i >= CPOOL_SIZE) {
ret = -ENOSPC;
goto out;
}
ret = __cpool_alloc_ahash(&cpool[i], alg);
if (!ret) {
ret = i;
if (i == cpool_populated)
cpool_populated++;
}
out:
mutex_unlock(&cpool_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(tcp_sigpool_alloc_ahash);
static void __cpool_free_entry(struct sigpool_entry *e)
{
crypto_free_ahash(e->hash);
kfree(e->alg);
memset(e, 0, sizeof(*e));
}
static void cpool_cleanup_work_cb(struct work_struct *work)
{
bool free_scratch = true;
unsigned int i;
mutex_lock(&cpool_mutex);
for (i = 0; i < cpool_populated; i++) {
if (kref_read(&cpool[i].kref) > 0) {
free_scratch = false;
continue;
}
if (!cpool[i].alg)
continue;
__cpool_free_entry(&cpool[i]);
}
if (free_scratch)
sigpool_scratch_free();
mutex_unlock(&cpool_mutex);
}
static DECLARE_WORK(cpool_cleanup_work, cpool_cleanup_work_cb);
static void cpool_schedule_cleanup(struct kref *kref)
{
schedule_work(&cpool_cleanup_work);
}
/**
* tcp_sigpool_release - decreases number of users for a pool. If it was
* the last user of the pool, releases any memory that was consumed.
* @id: tcp_sigpool that was previously allocated by tcp_sigpool_alloc_ahash()
*/
void tcp_sigpool_release(unsigned int id)
{
if (WARN_ON_ONCE(id >= cpool_populated || !cpool[id].alg))
return;
/* slow-path */
kref_put(&cpool[id].kref, cpool_schedule_cleanup);
}
EXPORT_SYMBOL_GPL(tcp_sigpool_release);
/**
* tcp_sigpool_get - increases number of users (refcounter) for a pool
* @id: tcp_sigpool that was previously allocated by tcp_sigpool_alloc_ahash()
*/
void tcp_sigpool_get(unsigned int id)
{
if (WARN_ON_ONCE(id >= cpool_populated || !cpool[id].alg))
return;
kref_get(&cpool[id].kref);
}
EXPORT_SYMBOL_GPL(tcp_sigpool_get);
int tcp_sigpool_start(unsigned int id, struct tcp_sigpool *c) __cond_acquires(RCU_BH)
{
struct crypto_ahash *hash;
rcu_read_lock_bh();
if (WARN_ON_ONCE(id >= cpool_populated || !cpool[id].alg)) {
rcu_read_unlock_bh();
return -EINVAL;
}
hash = crypto_clone_ahash(cpool[id].hash);
if (IS_ERR(hash)) {
rcu_read_unlock_bh();
return PTR_ERR(hash);
}
c->req = ahash_request_alloc(hash, GFP_ATOMIC);
if (!c->req) {
crypto_free_ahash(hash);
rcu_read_unlock_bh();
return -ENOMEM;
}
ahash_request_set_callback(c->req, 0, NULL, NULL);
/* Pairs with tcp_sigpool_reserve_scratch(), scratch area is
* valid (allocated) until tcp_sigpool_end().
*/
local_lock_nested_bh(&sigpool_scratch.bh_lock);
c->scratch = rcu_dereference_bh(*this_cpu_ptr(&sigpool_scratch.pad));
return 0;
}
EXPORT_SYMBOL_GPL(tcp_sigpool_start);
void tcp_sigpool_end(struct tcp_sigpool *c) __releases(RCU_BH)
{
struct crypto_ahash *hash = crypto_ahash_reqtfm(c->req);
local_unlock_nested_bh(&sigpool_scratch.bh_lock);
rcu_read_unlock_bh();
ahash_request_free(c->req);
crypto_free_ahash(hash);
}
EXPORT_SYMBOL_GPL(tcp_sigpool_end);
/**
* tcp_sigpool_algo - return algorithm of tcp_sigpool
* @id: tcp_sigpool that was previously allocated by tcp_sigpool_alloc_ahash()
* @buf: buffer to return name of algorithm
* @buf_len: size of @buf
*/
size_t tcp_sigpool_algo(unsigned int id, char *buf, size_t buf_len)
{
if (WARN_ON_ONCE(id >= cpool_populated || !cpool[id].alg))
return -EINVAL;
return strscpy(buf, cpool[id].alg, buf_len);
}
EXPORT_SYMBOL_GPL(tcp_sigpool_algo);
/**
* tcp_sigpool_hash_skb_data - hash data in skb with initialized tcp_sigpool
* @hp: tcp_sigpool pointer
* @skb: buffer to add sign for
* @header_len: TCP header length for this segment
*/
int tcp_sigpool_hash_skb_data(struct tcp_sigpool *hp,
const struct sk_buff *skb,
unsigned int header_len)
{
const unsigned int head_data_len = skb_headlen(skb) > header_len ?
skb_headlen(skb) - header_len : 0;
const struct skb_shared_info *shi = skb_shinfo(skb);
const struct tcphdr *tp = tcp_hdr(skb);
struct ahash_request *req = hp->req;
struct sk_buff *frag_iter;
struct scatterlist sg;
unsigned int i;
sg_init_table(&sg, 1);
sg_set_buf(&sg, ((u8 *)tp) + header_len, head_data_len);
ahash_request_set_crypt(req, &sg, NULL, head_data_len);
if (crypto_ahash_update(req))
return 1;
for (i = 0; i < shi->nr_frags; ++i) {
const skb_frag_t *f = &shi->frags[i];
unsigned int offset = skb_frag_off(f);
struct page *page;
page = skb_frag_page(f) + (offset >> PAGE_SHIFT);
sg_set_page(&sg, page, skb_frag_size(f), offset_in_page(offset));
ahash_request_set_crypt(req, &sg, NULL, skb_frag_size(f));
if (crypto_ahash_update(req))
return 1;
}
skb_walk_frags(skb, frag_iter)
if (tcp_sigpool_hash_skb_data(hp, frag_iter, 0))
return 1;
return 0;
}
EXPORT_SYMBOL(tcp_sigpool_hash_skb_data);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Per-CPU pool of crypto requests");
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