1// SPDX-License-Identifier: GPL-2.0-or-later
2
3#include <crypto/hash.h>
4#include <linux/cpu.h>
5#include <linux/kref.h>
6#include <linux/module.h>
7#include <linux/mutex.h>
8#include <linux/percpu.h>
9#include <linux/workqueue.h>
10#include <net/tcp.h>
11
12static size_t __scratch_size;
13struct sigpool_scratch {
14 local_lock_t bh_lock;
15 void __rcu *pad;
16};
17
18static DEFINE_PER_CPU(struct sigpool_scratch, sigpool_scratch) = {
19 .bh_lock = INIT_LOCAL_LOCK(bh_lock),
20};
21
22struct sigpool_entry {
23 struct crypto_ahash *hash;
24 const char *alg;
25 struct kref kref;
26 uint16_t needs_key:1,
27 reserved:15;
28};
29
30#define CPOOL_SIZE (PAGE_SIZE / sizeof(struct sigpool_entry))
31static struct sigpool_entry cpool[CPOOL_SIZE];
32static unsigned int cpool_populated;
33static DEFINE_MUTEX(cpool_mutex);
34
35/* Slow-path */
36struct scratches_to_free {
37 struct rcu_head rcu;
38 unsigned int cnt;
39 void *scratches[];
40};
41
42static void free_old_scratches(struct rcu_head *head)
43{
44 struct scratches_to_free *stf;
45
46 stf = container_of(head, struct scratches_to_free, rcu);
47 while (stf->cnt--)
48 kfree(objp: stf->scratches[stf->cnt]);
49 kfree(objp: stf);
50}
51
52/**
53 * sigpool_reserve_scratch - re-allocates scratch buffer, slow-path
54 * @size: request size for the scratch/temp buffer
55 */
56static int sigpool_reserve_scratch(size_t size)
57{
58 struct scratches_to_free *stf;
59 size_t stf_sz = struct_size(stf, scratches, num_possible_cpus());
60 int cpu, err = 0;
61
62 lockdep_assert_held(&cpool_mutex);
63 if (__scratch_size >= size)
64 return 0;
65
66 stf = kmalloc(stf_sz, GFP_KERNEL);
67 if (!stf)
68 return -ENOMEM;
69 stf->cnt = 0;
70
71 size = max(size, __scratch_size);
72 cpus_read_lock();
73 for_each_possible_cpu(cpu) {
74 void *scratch, *old_scratch;
75
76 scratch = kmalloc_node(size, GFP_KERNEL, cpu_to_node(cpu));
77 if (!scratch) {
78 err = -ENOMEM;
79 break;
80 }
81
82 old_scratch = rcu_replace_pointer(per_cpu(sigpool_scratch.pad, cpu),
83 scratch, lockdep_is_held(&cpool_mutex));
84 if (!cpu_online(cpu) || !old_scratch) {
85 kfree(objp: old_scratch);
86 continue;
87 }
88 stf->scratches[stf->cnt++] = old_scratch;
89 }
90 cpus_read_unlock();
91 if (!err)
92 __scratch_size = size;
93
94 call_rcu(head: &stf->rcu, func: free_old_scratches);
95 return err;
96}
97
98static void sigpool_scratch_free(void)
99{
100 int cpu;
101
102 for_each_possible_cpu(cpu)
103 kfree(rcu_replace_pointer(per_cpu(sigpool_scratch.pad, cpu),
104 NULL, lockdep_is_held(&cpool_mutex)));
105 __scratch_size = 0;
106}
107
108static int __cpool_try_clone(struct crypto_ahash *hash)
109{
110 struct crypto_ahash *tmp;
111
112 tmp = crypto_clone_ahash(tfm: hash);
113 if (IS_ERR(ptr: tmp))
114 return PTR_ERR(ptr: tmp);
115
116 crypto_free_ahash(tfm: tmp);
117 return 0;
118}
119
120static int __cpool_alloc_ahash(struct sigpool_entry *e, const char *alg)
121{
122 struct crypto_ahash *cpu0_hash;
123 int ret;
124
125 e->alg = kstrdup(s: alg, GFP_KERNEL);
126 if (!e->alg)
127 return -ENOMEM;
128
129 cpu0_hash = crypto_alloc_ahash(alg_name: alg, type: 0, CRYPTO_ALG_ASYNC);
130 if (IS_ERR(ptr: cpu0_hash)) {
131 ret = PTR_ERR(ptr: cpu0_hash);
132 goto out_free_alg;
133 }
134
135 e->needs_key = crypto_ahash_get_flags(tfm: cpu0_hash) & CRYPTO_TFM_NEED_KEY;
136
137 ret = __cpool_try_clone(hash: cpu0_hash);
138 if (ret)
139 goto out_free_cpu0_hash;
140 e->hash = cpu0_hash;
141 kref_init(kref: &e->kref);
142 return 0;
143
144out_free_cpu0_hash:
145 crypto_free_ahash(tfm: cpu0_hash);
146out_free_alg:
147 kfree(objp: e->alg);
148 e->alg = NULL;
149 return ret;
150}
151
152/**
153 * tcp_sigpool_alloc_ahash - allocates pool for ahash requests
154 * @alg: name of async hash algorithm
155 * @scratch_size: reserve a tcp_sigpool::scratch buffer of this size
156 */
157int tcp_sigpool_alloc_ahash(const char *alg, size_t scratch_size)
158{
159 int i, ret;
160
161 /* slow-path */
162 mutex_lock(&cpool_mutex);
163 ret = sigpool_reserve_scratch(size: scratch_size);
164 if (ret)
165 goto out;
166 for (i = 0; i < cpool_populated; i++) {
167 if (!cpool[i].alg)
168 continue;
169 if (strcmp(cpool[i].alg, alg))
170 continue;
171
172 /* pairs with tcp_sigpool_release() */
173 if (!kref_get_unless_zero(kref: &cpool[i].kref))
174 kref_init(kref: &cpool[i].kref);
175 ret = i;
176 goto out;
177 }
178
179 for (i = 0; i < cpool_populated; i++) {
180 if (!cpool[i].alg)
181 break;
182 }
183 if (i >= CPOOL_SIZE) {
184 ret = -ENOSPC;
185 goto out;
186 }
187
188 ret = __cpool_alloc_ahash(e: &cpool[i], alg);
189 if (!ret) {
190 ret = i;
191 if (i == cpool_populated)
192 cpool_populated++;
193 }
194out:
195 mutex_unlock(lock: &cpool_mutex);
196 return ret;
197}
198EXPORT_SYMBOL_GPL(tcp_sigpool_alloc_ahash);
199
200static void __cpool_free_entry(struct sigpool_entry *e)
201{
202 crypto_free_ahash(tfm: e->hash);
203 kfree(objp: e->alg);
204 memset(e, 0, sizeof(*e));
205}
206
207static void cpool_cleanup_work_cb(struct work_struct *work)
208{
209 bool free_scratch = true;
210 unsigned int i;
211
212 mutex_lock(&cpool_mutex);
213 for (i = 0; i < cpool_populated; i++) {
214 if (kref_read(kref: &cpool[i].kref) > 0) {
215 free_scratch = false;
216 continue;
217 }
218 if (!cpool[i].alg)
219 continue;
220 __cpool_free_entry(e: &cpool[i]);
221 }
222 if (free_scratch)
223 sigpool_scratch_free();
224 mutex_unlock(lock: &cpool_mutex);
225}
226
227static DECLARE_WORK(cpool_cleanup_work, cpool_cleanup_work_cb);
228static void cpool_schedule_cleanup(struct kref *kref)
229{
230 schedule_work(work: &cpool_cleanup_work);
231}
232
233/**
234 * tcp_sigpool_release - decreases number of users for a pool. If it was
235 * the last user of the pool, releases any memory that was consumed.
236 * @id: tcp_sigpool that was previously allocated by tcp_sigpool_alloc_ahash()
237 */
238void tcp_sigpool_release(unsigned int id)
239{
240 if (WARN_ON_ONCE(id >= cpool_populated || !cpool[id].alg))
241 return;
242
243 /* slow-path */
244 kref_put(kref: &cpool[id].kref, release: cpool_schedule_cleanup);
245}
246EXPORT_SYMBOL_GPL(tcp_sigpool_release);
247
248/**
249 * tcp_sigpool_get - increases number of users (refcounter) for a pool
250 * @id: tcp_sigpool that was previously allocated by tcp_sigpool_alloc_ahash()
251 */
252void tcp_sigpool_get(unsigned int id)
253{
254 if (WARN_ON_ONCE(id >= cpool_populated || !cpool[id].alg))
255 return;
256 kref_get(kref: &cpool[id].kref);
257}
258EXPORT_SYMBOL_GPL(tcp_sigpool_get);
259
260int tcp_sigpool_start(unsigned int id, struct tcp_sigpool *c) __cond_acquires(RCU_BH)
261{
262 struct crypto_ahash *hash;
263
264 rcu_read_lock_bh();
265 if (WARN_ON_ONCE(id >= cpool_populated || !cpool[id].alg)) {
266 rcu_read_unlock_bh();
267 return -EINVAL;
268 }
269
270 hash = crypto_clone_ahash(tfm: cpool[id].hash);
271 if (IS_ERR(ptr: hash)) {
272 rcu_read_unlock_bh();
273 return PTR_ERR(ptr: hash);
274 }
275
276 c->req = ahash_request_alloc(hash, GFP_ATOMIC);
277 if (!c->req) {
278 crypto_free_ahash(tfm: hash);
279 rcu_read_unlock_bh();
280 return -ENOMEM;
281 }
282 ahash_request_set_callback(req: c->req, flags: 0, NULL, NULL);
283
284 /* Pairs with tcp_sigpool_reserve_scratch(), scratch area is
285 * valid (allocated) until tcp_sigpool_end().
286 */
287 local_lock_nested_bh(&sigpool_scratch.bh_lock);
288 c->scratch = rcu_dereference_bh(*this_cpu_ptr(&sigpool_scratch.pad));
289 return 0;
290}
291EXPORT_SYMBOL_GPL(tcp_sigpool_start);
292
293void tcp_sigpool_end(struct tcp_sigpool *c) __releases(RCU_BH)
294{
295 struct crypto_ahash *hash = crypto_ahash_reqtfm(req: c->req);
296
297 local_unlock_nested_bh(&sigpool_scratch.bh_lock);
298 rcu_read_unlock_bh();
299 ahash_request_free(req: c->req);
300 crypto_free_ahash(tfm: hash);
301}
302EXPORT_SYMBOL_GPL(tcp_sigpool_end);
303
304/**
305 * tcp_sigpool_algo - return algorithm of tcp_sigpool
306 * @id: tcp_sigpool that was previously allocated by tcp_sigpool_alloc_ahash()
307 * @buf: buffer to return name of algorithm
308 * @buf_len: size of @buf
309 */
310size_t tcp_sigpool_algo(unsigned int id, char *buf, size_t buf_len)
311{
312 if (WARN_ON_ONCE(id >= cpool_populated || !cpool[id].alg))
313 return -EINVAL;
314
315 return strscpy(buf, cpool[id].alg, buf_len);
316}
317EXPORT_SYMBOL_GPL(tcp_sigpool_algo);
318
319/**
320 * tcp_sigpool_hash_skb_data - hash data in skb with initialized tcp_sigpool
321 * @hp: tcp_sigpool pointer
322 * @skb: buffer to add sign for
323 * @header_len: TCP header length for this segment
324 */
325int tcp_sigpool_hash_skb_data(struct tcp_sigpool *hp,
326 const struct sk_buff *skb,
327 unsigned int header_len)
328{
329 const unsigned int head_data_len = skb_headlen(skb) > header_len ?
330 skb_headlen(skb) - header_len : 0;
331 const struct skb_shared_info *shi = skb_shinfo(skb);
332 const struct tcphdr *tp = tcp_hdr(skb);
333 struct ahash_request *req = hp->req;
334 struct sk_buff *frag_iter;
335 struct scatterlist sg;
336 unsigned int i;
337
338 sg_init_table(&sg, 1);
339
340 sg_set_buf(sg: &sg, buf: ((u8 *)tp) + header_len, buflen: head_data_len);
341 ahash_request_set_crypt(req, src: &sg, NULL, nbytes: head_data_len);
342 if (crypto_ahash_update(req))
343 return 1;
344
345 for (i = 0; i < shi->nr_frags; ++i) {
346 const skb_frag_t *f = &shi->frags[i];
347 unsigned int offset = skb_frag_off(frag: f);
348 struct page *page;
349
350 page = skb_frag_page(frag: f) + (offset >> PAGE_SHIFT);
351 sg_set_page(sg: &sg, page, len: skb_frag_size(frag: f), offset_in_page(offset));
352 ahash_request_set_crypt(req, src: &sg, NULL, nbytes: skb_frag_size(frag: f));
353 if (crypto_ahash_update(req))
354 return 1;
355 }
356
357 skb_walk_frags(skb, frag_iter)
358 if (tcp_sigpool_hash_skb_data(hp, skb: frag_iter, header_len: 0))
359 return 1;
360
361 return 0;
362}
363EXPORT_SYMBOL(tcp_sigpool_hash_skb_data);
364
365MODULE_LICENSE("GPL");
366MODULE_DESCRIPTION("Per-CPU pool of crypto requests");
367

source code of linux/net/ipv4/tcp_sigpool.c