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