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
12 static size_t __scratch_size;
13 struct sigpool_scratch {
14 local_lock_t bh_lock;
15 void __rcu *pad;
16 };
17
18 static DEFINE_PER_CPU(struct sigpool_scratch, sigpool_scratch) = {
19 .bh_lock = INIT_LOCAL_LOCK(bh_lock),
20 };
21
22 struct 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))
31 static struct sigpool_entry cpool[CPOOL_SIZE];
32 static unsigned int cpool_populated;
33 static DEFINE_MUTEX(cpool_mutex);
34
35 /* Slow-path */
36 struct scratches_to_free {
37 struct rcu_head rcu;
38 unsigned int cnt;
39 void *scratches[];
40 };
41
free_old_scratches(struct rcu_head * head)42 static 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(stf->scratches[stf->cnt]);
49 kfree(stf);
50 }
51
52 /**
53 * sigpool_reserve_scratch - re-allocates scratch buffer, slow-path
54 * @size: request size for the scratch/temp buffer
55 */
sigpool_reserve_scratch(size_t size)56 static 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(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(&stf->rcu, free_old_scratches);
95 return err;
96 }
97
sigpool_scratch_free(void)98 static 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
__cpool_try_clone(struct crypto_ahash * hash)108 static int __cpool_try_clone(struct crypto_ahash *hash)
109 {
110 struct crypto_ahash *tmp;
111
112 tmp = crypto_clone_ahash(hash);
113 if (IS_ERR(tmp))
114 return PTR_ERR(tmp);
115
116 crypto_free_ahash(tmp);
117 return 0;
118 }
119
__cpool_alloc_ahash(struct sigpool_entry * e,const char * alg)120 static 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(alg, GFP_KERNEL);
126 if (!e->alg)
127 return -ENOMEM;
128
129 cpu0_hash = crypto_alloc_ahash(alg, 0, CRYPTO_ALG_ASYNC);
130 if (IS_ERR(cpu0_hash)) {
131 ret = PTR_ERR(cpu0_hash);
132 goto out_free_alg;
133 }
134
135 e->needs_key = crypto_ahash_get_flags(cpu0_hash) & CRYPTO_TFM_NEED_KEY;
136
137 ret = __cpool_try_clone(cpu0_hash);
138 if (ret)
139 goto out_free_cpu0_hash;
140 e->hash = cpu0_hash;
141 kref_init(&e->kref);
142 return 0;
143
144 out_free_cpu0_hash:
145 crypto_free_ahash(cpu0_hash);
146 out_free_alg:
147 kfree(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 */
tcp_sigpool_alloc_ahash(const char * alg,size_t scratch_size)157 int 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(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(&cpool[i].kref))
174 kref_init(&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(&cpool[i], alg);
189 if (!ret) {
190 ret = i;
191 if (i == cpool_populated)
192 cpool_populated++;
193 }
194 out:
195 mutex_unlock(&cpool_mutex);
196 return ret;
197 }
198 EXPORT_SYMBOL_GPL(tcp_sigpool_alloc_ahash);
199
__cpool_free_entry(struct sigpool_entry * e)200 static void __cpool_free_entry(struct sigpool_entry *e)
201 {
202 crypto_free_ahash(e->hash);
203 kfree(e->alg);
204 memset(e, 0, sizeof(*e));
205 }
206
cpool_cleanup_work_cb(struct work_struct * work)207 static 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(&cpool[i].kref) > 0) {
215 free_scratch = false;
216 continue;
217 }
218 if (!cpool[i].alg)
219 continue;
220 __cpool_free_entry(&cpool[i]);
221 }
222 if (free_scratch)
223 sigpool_scratch_free();
224 mutex_unlock(&cpool_mutex);
225 }
226
227 static DECLARE_WORK(cpool_cleanup_work, cpool_cleanup_work_cb);
cpool_schedule_cleanup(struct kref * kref)228 static void cpool_schedule_cleanup(struct kref *kref)
229 {
230 schedule_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 */
tcp_sigpool_release(unsigned int id)238 void 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(&cpool[id].kref, cpool_schedule_cleanup);
245 }
246 EXPORT_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 */
tcp_sigpool_get(unsigned int id)252 void tcp_sigpool_get(unsigned int id)
253 {
254 if (WARN_ON_ONCE(id >= cpool_populated || !cpool[id].alg))
255 return;
256 kref_get(&cpool[id].kref);
257 }
258 EXPORT_SYMBOL_GPL(tcp_sigpool_get);
259
tcp_sigpool_start(unsigned int id,struct tcp_sigpool * c)260 int 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(cpool[id].hash);
271 if (IS_ERR(hash)) {
272 rcu_read_unlock_bh();
273 return PTR_ERR(hash);
274 }
275
276 c->req = ahash_request_alloc(hash, GFP_ATOMIC);
277 if (!c->req) {
278 crypto_free_ahash(hash);
279 rcu_read_unlock_bh();
280 return -ENOMEM;
281 }
282 ahash_request_set_callback(c->req, 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 }
291 EXPORT_SYMBOL_GPL(tcp_sigpool_start);
292
tcp_sigpool_end(struct tcp_sigpool * c)293 void tcp_sigpool_end(struct tcp_sigpool *c) __releases(RCU_BH)
294 {
295 struct crypto_ahash *hash = crypto_ahash_reqtfm(c->req);
296
297 local_unlock_nested_bh(&sigpool_scratch.bh_lock);
298 rcu_read_unlock_bh();
299 ahash_request_free(c->req);
300 crypto_free_ahash(hash);
301 }
302 EXPORT_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 */
tcp_sigpool_algo(unsigned int id,char * buf,size_t buf_len)310 size_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 }
317 EXPORT_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 */
tcp_sigpool_hash_skb_data(struct tcp_sigpool * hp,const struct sk_buff * skb,unsigned int header_len)325 int 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, ((u8 *)tp) + header_len, head_data_len);
341 ahash_request_set_crypt(req, &sg, NULL, 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(f);
348 struct page *page;
349
350 page = skb_frag_page(f) + (offset >> PAGE_SHIFT);
351 sg_set_page(&sg, page, skb_frag_size(f), offset_in_page(offset));
352 ahash_request_set_crypt(req, &sg, NULL, skb_frag_size(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, frag_iter, 0))
359 return 1;
360
361 return 0;
362 }
363 EXPORT_SYMBOL(tcp_sigpool_hash_skb_data);
364
365 MODULE_LICENSE("GPL");
366 MODULE_DESCRIPTION("Per-CPU pool of crypto requests");
367