xref: /openssl/crypto/initthread.c (revision 36840ab5)
1 /*
2  * Copyright 2019-2023 The OpenSSL Project Authors. All Rights Reserved.
3  *
4  * Licensed under the Apache License 2.0 (the "License").  You may not use
5  * this file except in compliance with the License.  You can obtain a copy
6  * in the file LICENSE in the source distribution or at
7  * https://www.openssl.org/source/license.html
8  */
9 
10 #include <openssl/crypto.h>
11 #include <openssl/core_dispatch.h>
12 #include "crypto/cryptlib.h"
13 #include "prov/providercommon.h"
14 #include "internal/thread_once.h"
15 #include "crypto/context.h"
16 
17 #ifdef FIPS_MODULE
18 #include "prov/provider_ctx.h"
19 
20 /*
21  * Thread aware code may want to be told about thread stop events. We register
22  * to hear about those thread stop events when we see a new thread has started.
23  * We call the ossl_init_thread_start function to do that. In the FIPS provider
24  * we have our own copy of ossl_init_thread_start, which cascades notifications
25  * about threads stopping from libcrypto to all the code in the FIPS provider
26  * that needs to know about it.
27  *
28  * The FIPS provider tells libcrypto about which threads it is interested in
29  * by calling "c_thread_start" which is a function pointer created during
30  * provider initialisation (i.e. OSSL_provider_init).
31  */
32 extern OSSL_FUNC_core_thread_start_fn *c_thread_start;
33 #endif
34 
35 typedef struct thread_event_handler_st THREAD_EVENT_HANDLER;
36 struct thread_event_handler_st {
37 #ifndef FIPS_MODULE
38     const void *index;
39 #endif
40     void *arg;
41     OSSL_thread_stop_handler_fn handfn;
42     THREAD_EVENT_HANDLER *next;
43 };
44 
45 #ifndef FIPS_MODULE
46 DEFINE_SPECIAL_STACK_OF(THREAD_EVENT_HANDLER_PTR, THREAD_EVENT_HANDLER *)
47 
48 typedef struct global_tevent_register_st GLOBAL_TEVENT_REGISTER;
49 struct global_tevent_register_st {
50     STACK_OF(THREAD_EVENT_HANDLER_PTR) *skhands;
51     CRYPTO_RWLOCK *lock;
52 };
53 
54 static GLOBAL_TEVENT_REGISTER *glob_tevent_reg = NULL;
55 
56 static CRYPTO_ONCE tevent_register_runonce = CRYPTO_ONCE_STATIC_INIT;
57 
DEFINE_RUN_ONCE_STATIC(create_global_tevent_register)58 DEFINE_RUN_ONCE_STATIC(create_global_tevent_register)
59 {
60     glob_tevent_reg = OPENSSL_zalloc(sizeof(*glob_tevent_reg));
61     if (glob_tevent_reg == NULL)
62         return 0;
63 
64     glob_tevent_reg->skhands = sk_THREAD_EVENT_HANDLER_PTR_new_null();
65     glob_tevent_reg->lock = CRYPTO_THREAD_lock_new();
66     if (glob_tevent_reg->skhands == NULL || glob_tevent_reg->lock == NULL) {
67         sk_THREAD_EVENT_HANDLER_PTR_free(glob_tevent_reg->skhands);
68         CRYPTO_THREAD_lock_free(glob_tevent_reg->lock);
69         OPENSSL_free(glob_tevent_reg);
70         glob_tevent_reg = NULL;
71         return 0;
72     }
73 
74     return 1;
75 }
76 
get_global_tevent_register(void)77 static GLOBAL_TEVENT_REGISTER *get_global_tevent_register(void)
78 {
79     if (!RUN_ONCE(&tevent_register_runonce, create_global_tevent_register))
80         return NULL;
81     return glob_tevent_reg;
82 }
83 #endif
84 
85 #ifndef FIPS_MODULE
86 static int  init_thread_push_handlers(THREAD_EVENT_HANDLER **hands);
87 static void init_thread_remove_handlers(THREAD_EVENT_HANDLER **handsin);
88 static void init_thread_destructor(void *hands);
89 static int  init_thread_deregister(void *arg, int all);
90 #endif
91 static void init_thread_stop(void *arg, THREAD_EVENT_HANDLER **hands);
92 
93 static THREAD_EVENT_HANDLER **
init_get_thread_local(CRYPTO_THREAD_LOCAL * local,int alloc,int keep)94 init_get_thread_local(CRYPTO_THREAD_LOCAL *local, int alloc, int keep)
95 {
96     THREAD_EVENT_HANDLER **hands = CRYPTO_THREAD_get_local(local);
97 
98     if (alloc) {
99         if (hands == NULL) {
100 
101             if ((hands = OPENSSL_zalloc(sizeof(*hands))) == NULL)
102                 return NULL;
103 
104             if (!CRYPTO_THREAD_set_local(local, hands)) {
105                 OPENSSL_free(hands);
106                 return NULL;
107             }
108 
109 #ifndef FIPS_MODULE
110             if (!init_thread_push_handlers(hands)) {
111                 CRYPTO_THREAD_set_local(local, NULL);
112                 OPENSSL_free(hands);
113                 return NULL;
114             }
115 #endif
116         }
117     } else if (!keep) {
118         CRYPTO_THREAD_set_local(local, NULL);
119     }
120 
121     return hands;
122 }
123 
124 #ifndef FIPS_MODULE
125 /*
126  * Since per-thread-specific-data destructors are not universally
127  * available, i.e. not on Windows, only below CRYPTO_THREAD_LOCAL key
128  * is assumed to have destructor associated. And then an effort is made
129  * to call this single destructor on non-pthread platform[s].
130  *
131  * Initial value is "impossible". It is used as guard value to shortcut
132  * destructor for threads terminating before libcrypto is initialized or
133  * after it's de-initialized. Access to the key doesn't have to be
134  * serialized for the said threads, because they didn't use libcrypto
135  * and it doesn't matter if they pick "impossible" or dereference real
136  * key value and pull NULL past initialization in the first thread that
137  * intends to use libcrypto.
138  */
139 static union {
140     long sane;
141     CRYPTO_THREAD_LOCAL value;
142 } destructor_key = { -1 };
143 
144 /*
145  * The thread event handler list is a thread specific linked list
146  * of callback functions which are invoked in list order by the
147  * current thread in case of certain events. (Currently, there is
148  * only one type of event, the 'thread stop' event.)
149  *
150  * We also keep a global reference to that linked list, so that we
151  * can deregister handlers if necessary before all the threads are
152  * stopped.
153  */
init_thread_push_handlers(THREAD_EVENT_HANDLER ** hands)154 static int init_thread_push_handlers(THREAD_EVENT_HANDLER **hands)
155 {
156     int ret;
157     GLOBAL_TEVENT_REGISTER *gtr;
158 
159     gtr = get_global_tevent_register();
160     if (gtr == NULL)
161         return 0;
162 
163     if (!CRYPTO_THREAD_write_lock(gtr->lock))
164         return 0;
165     ret = (sk_THREAD_EVENT_HANDLER_PTR_push(gtr->skhands, hands) != 0);
166     CRYPTO_THREAD_unlock(gtr->lock);
167 
168     return ret;
169 }
170 
init_thread_remove_handlers(THREAD_EVENT_HANDLER ** handsin)171 static void init_thread_remove_handlers(THREAD_EVENT_HANDLER **handsin)
172 {
173     GLOBAL_TEVENT_REGISTER *gtr;
174     int i;
175 
176     gtr = get_global_tevent_register();
177     if (gtr == NULL)
178         return;
179     if (!CRYPTO_THREAD_write_lock(gtr->lock))
180         return;
181     for (i = 0; i < sk_THREAD_EVENT_HANDLER_PTR_num(gtr->skhands); i++) {
182         THREAD_EVENT_HANDLER **hands
183             = sk_THREAD_EVENT_HANDLER_PTR_value(gtr->skhands, i);
184 
185         if (hands == handsin) {
186             sk_THREAD_EVENT_HANDLER_PTR_delete(gtr->skhands, i);
187             CRYPTO_THREAD_unlock(gtr->lock);
188             return;
189         }
190     }
191     CRYPTO_THREAD_unlock(gtr->lock);
192     return;
193 }
194 
init_thread_destructor(void * hands)195 static void init_thread_destructor(void *hands)
196 {
197     init_thread_stop(NULL, (THREAD_EVENT_HANDLER **)hands);
198     init_thread_remove_handlers(hands);
199     OPENSSL_free(hands);
200 }
201 
ossl_init_thread(void)202 int ossl_init_thread(void)
203 {
204     if (!CRYPTO_THREAD_init_local(&destructor_key.value,
205                                   init_thread_destructor))
206         return 0;
207 
208     return 1;
209 }
210 
ossl_cleanup_thread(void)211 void ossl_cleanup_thread(void)
212 {
213     init_thread_deregister(NULL, 1);
214     CRYPTO_THREAD_cleanup_local(&destructor_key.value);
215     destructor_key.sane = -1;
216 }
217 
OPENSSL_thread_stop_ex(OSSL_LIB_CTX * ctx)218 void OPENSSL_thread_stop_ex(OSSL_LIB_CTX *ctx)
219 {
220     ctx = ossl_lib_ctx_get_concrete(ctx);
221     /*
222      * It would be nice if we could figure out a way to do this on all threads
223      * that have used the OSSL_LIB_CTX when the context is freed. This is
224      * currently not possible due to the use of thread local variables.
225      */
226     ossl_ctx_thread_stop(ctx);
227 }
228 
OPENSSL_thread_stop(void)229 void OPENSSL_thread_stop(void)
230 {
231     if (destructor_key.sane != -1) {
232         THREAD_EVENT_HANDLER **hands
233             = init_get_thread_local(&destructor_key.value, 0, 0);
234         init_thread_stop(NULL, hands);
235 
236         init_thread_remove_handlers(hands);
237         OPENSSL_free(hands);
238     }
239 }
240 
ossl_ctx_thread_stop(OSSL_LIB_CTX * ctx)241 void ossl_ctx_thread_stop(OSSL_LIB_CTX *ctx)
242 {
243     if (destructor_key.sane != -1) {
244         THREAD_EVENT_HANDLER **hands
245             = init_get_thread_local(&destructor_key.value, 0, 1);
246         init_thread_stop(ctx, hands);
247     }
248 }
249 
250 #else
251 
252 static void ossl_arg_thread_stop(void *arg);
253 
254 /* Register the current thread so that we are informed if it gets stopped */
ossl_thread_register_fips(OSSL_LIB_CTX * libctx)255 int ossl_thread_register_fips(OSSL_LIB_CTX *libctx)
256 {
257     return c_thread_start(FIPS_get_core_handle(libctx), ossl_arg_thread_stop,
258                           libctx);
259 }
260 
ossl_thread_event_ctx_new(OSSL_LIB_CTX * libctx)261 void *ossl_thread_event_ctx_new(OSSL_LIB_CTX *libctx)
262 {
263     THREAD_EVENT_HANDLER **hands = NULL;
264     CRYPTO_THREAD_LOCAL *tlocal = OPENSSL_zalloc(sizeof(*tlocal));
265 
266     if (tlocal == NULL)
267         return NULL;
268 
269     if (!CRYPTO_THREAD_init_local(tlocal, NULL))
270         goto deinit;
271 
272     hands = OPENSSL_zalloc(sizeof(*hands));
273     if (hands == NULL)
274         goto err;
275 
276     if (!CRYPTO_THREAD_set_local(tlocal, hands))
277         goto err;
278 
279     /*
280      * We should ideally call ossl_thread_register_fips() here. This function
281      * is called during the startup of the FIPS provider and we need to ensure
282      * that the main thread is registered to receive thread callbacks in order
283      * to free |hands| that we allocated above. However we are too early in
284      * the FIPS provider initialisation that FIPS_get_core_handle() doesn't work
285      * yet. So we defer this to the main provider OSSL_provider_init_int()
286      * function.
287      */
288 
289     return tlocal;
290  err:
291     OPENSSL_free(hands);
292     CRYPTO_THREAD_cleanup_local(tlocal);
293  deinit:
294     OPENSSL_free(tlocal);
295     return NULL;
296 }
297 
ossl_thread_event_ctx_free(void * tlocal)298 void ossl_thread_event_ctx_free(void *tlocal)
299 {
300     CRYPTO_THREAD_cleanup_local(tlocal);
301     OPENSSL_free(tlocal);
302 }
303 
ossl_arg_thread_stop(void * arg)304 static void ossl_arg_thread_stop(void *arg)
305 {
306     ossl_ctx_thread_stop((OSSL_LIB_CTX *)arg);
307 }
308 
ossl_ctx_thread_stop(OSSL_LIB_CTX * ctx)309 void ossl_ctx_thread_stop(OSSL_LIB_CTX *ctx)
310 {
311     THREAD_EVENT_HANDLER **hands;
312     CRYPTO_THREAD_LOCAL *local
313         = ossl_lib_ctx_get_data(ctx, OSSL_LIB_CTX_THREAD_EVENT_HANDLER_INDEX);
314 
315     if (local == NULL)
316         return;
317     hands = init_get_thread_local(local, 0, 0);
318     init_thread_stop(ctx, hands);
319     OPENSSL_free(hands);
320 }
321 #endif /* FIPS_MODULE */
322 
323 
init_thread_stop(void * arg,THREAD_EVENT_HANDLER ** hands)324 static void init_thread_stop(void *arg, THREAD_EVENT_HANDLER **hands)
325 {
326     THREAD_EVENT_HANDLER *curr, *prev = NULL, *tmp;
327 #ifndef FIPS_MODULE
328     GLOBAL_TEVENT_REGISTER *gtr;
329 #endif
330 
331     /* Can't do much about this */
332     if (hands == NULL)
333         return;
334 
335 #ifndef FIPS_MODULE
336     gtr = get_global_tevent_register();
337     if (gtr == NULL)
338         return;
339 
340     if (!CRYPTO_THREAD_write_lock(gtr->lock))
341         return;
342 #endif
343 
344     curr = *hands;
345     while (curr != NULL) {
346         if (arg != NULL && curr->arg != arg) {
347             prev = curr;
348             curr = curr->next;
349             continue;
350         }
351         curr->handfn(curr->arg);
352         if (prev == NULL)
353             *hands = curr->next;
354         else
355             prev->next = curr->next;
356 
357         tmp = curr;
358         curr = curr->next;
359 
360         OPENSSL_free(tmp);
361     }
362 #ifndef FIPS_MODULE
363     CRYPTO_THREAD_unlock(gtr->lock);
364 #endif
365 }
366 
ossl_init_thread_start(const void * index,void * arg,OSSL_thread_stop_handler_fn handfn)367 int ossl_init_thread_start(const void *index, void *arg,
368                            OSSL_thread_stop_handler_fn handfn)
369 {
370     THREAD_EVENT_HANDLER **hands;
371     THREAD_EVENT_HANDLER *hand;
372 #ifdef FIPS_MODULE
373     OSSL_LIB_CTX *ctx = arg;
374 
375     /*
376      * In FIPS mode the list of THREAD_EVENT_HANDLERs is unique per combination
377      * of OSSL_LIB_CTX and thread. This is because in FIPS mode each
378      * OSSL_LIB_CTX gets informed about thread stop events individually.
379      */
380     CRYPTO_THREAD_LOCAL *local
381         = ossl_lib_ctx_get_data(ctx, OSSL_LIB_CTX_THREAD_EVENT_HANDLER_INDEX);
382 #else
383     /*
384      * Outside of FIPS mode the list of THREAD_EVENT_HANDLERs is unique per
385      * thread, but may hold multiple OSSL_LIB_CTXs. We only get told about
386      * thread stop events globally, so we have to ensure all affected
387      * OSSL_LIB_CTXs are informed.
388      */
389     CRYPTO_THREAD_LOCAL *local = &destructor_key.value;
390 #endif
391 
392     hands = init_get_thread_local(local, 1, 0);
393     if (hands == NULL)
394         return 0;
395 
396 #ifdef FIPS_MODULE
397     if (*hands == NULL) {
398         /*
399          * We've not yet registered any handlers for this thread. We need to get
400          * libcrypto to tell us about later thread stop events. c_thread_start
401          * is a callback to libcrypto defined in fipsprov.c
402          */
403         if (!ossl_thread_register_fips(ctx))
404             return 0;
405     }
406 #endif
407 
408     hand = OPENSSL_malloc(sizeof(*hand));
409     if (hand == NULL)
410         return 0;
411 
412     hand->handfn = handfn;
413     hand->arg = arg;
414 #ifndef FIPS_MODULE
415     hand->index = index;
416 #endif
417     hand->next = *hands;
418     *hands = hand;
419 
420     return 1;
421 }
422 
423 #ifndef FIPS_MODULE
init_thread_deregister(void * index,int all)424 static int init_thread_deregister(void *index, int all)
425 {
426     GLOBAL_TEVENT_REGISTER *gtr;
427     int i;
428 
429     gtr = get_global_tevent_register();
430     if (gtr == NULL)
431         return 0;
432     if (!all) {
433         if (!CRYPTO_THREAD_write_lock(gtr->lock))
434             return 0;
435     } else {
436         glob_tevent_reg = NULL;
437     }
438     for (i = 0; i < sk_THREAD_EVENT_HANDLER_PTR_num(gtr->skhands); i++) {
439         THREAD_EVENT_HANDLER **hands
440             = sk_THREAD_EVENT_HANDLER_PTR_value(gtr->skhands, i);
441         THREAD_EVENT_HANDLER *curr = NULL, *prev = NULL, *tmp;
442 
443         if (hands == NULL) {
444             if (!all)
445                 CRYPTO_THREAD_unlock(gtr->lock);
446             return 0;
447         }
448         curr = *hands;
449         while (curr != NULL) {
450             if (all || curr->index == index) {
451                 if (prev != NULL)
452                     prev->next = curr->next;
453                 else
454                     *hands = curr->next;
455                 tmp = curr;
456                 curr = curr->next;
457                 OPENSSL_free(tmp);
458                 continue;
459             }
460             prev = curr;
461             curr = curr->next;
462         }
463         if (all)
464             OPENSSL_free(hands);
465     }
466     if (all) {
467         CRYPTO_THREAD_lock_free(gtr->lock);
468         sk_THREAD_EVENT_HANDLER_PTR_free(gtr->skhands);
469         OPENSSL_free(gtr);
470     } else {
471         CRYPTO_THREAD_unlock(gtr->lock);
472     }
473     return 1;
474 }
475 
ossl_init_thread_deregister(void * index)476 int ossl_init_thread_deregister(void *index)
477 {
478     return init_thread_deregister(index, 0);
479 }
480 #endif
481