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Optimize session cache flushing

Sort SSL_SESSION structures by timeout in the linked list.
Iterate over the linked list for timeout, stopping when no more
session can be flushed.
Do SSL_SESSION_free() outside of SSL_CTX lock
Update timeout upon use

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/8687)
master
Todd Short 3 years ago
committed by Pauli
parent
commit
25959e04c3
8 changed files with 310 additions and 59 deletions
  1. +5
    -0
      doc/man3/SSL_CTX_set_session_cache_mode.pod
  2. +1
    -0
      include/openssl/ssl.h.in
  3. +6
    -5
      ssl/ssl_asn1.c
  4. +7
    -2
      ssl/ssl_local.h
  5. +162
    -45
      ssl/ssl_sess.c
  6. +2
    -5
      ssl/statem/statem_clnt.c
  7. +3
    -2
      ssl/statem/statem_srvr.c
  8. +124
    -0
      test/sslapitest.c

+ 5
- 0
doc/man3/SSL_CTX_set_session_cache_mode.pod View File

@ -105,6 +105,11 @@ prevents these additions to the internal cache as well.
Enable both SSL_SESS_CACHE_NO_INTERNAL_LOOKUP and
SSL_SESS_CACHE_NO_INTERNAL_STORE at the same time.
=item SSL_SESS_CACHE_UPDATE_TIME
Updates the timestamp of the session when it is used, increasing the lifespan
of the session. The session timeout applies to last use, rather then creation
time.
=back


+ 1
- 0
include/openssl/ssl.h.in View File

@ -670,6 +670,7 @@ typedef int (*GEN_SESSION_CB) (SSL *ssl, unsigned char *id,
# define SSL_SESS_CACHE_NO_INTERNAL_STORE 0x0200
# define SSL_SESS_CACHE_NO_INTERNAL \
(SSL_SESS_CACHE_NO_INTERNAL_LOOKUP|SSL_SESS_CACHE_NO_INTERNAL_STORE)
# define SSL_SESS_CACHE_UPDATE_TIME 0x0400
LHASH_OF(SSL_SESSION) *SSL_CTX_sessions(SSL_CTX *ctx);
# define SSL_CTX_sess_number(ctx) \


+ 6
- 5
ssl/ssl_asn1.c View File

@ -163,8 +163,8 @@ int i2d_SSL_SESSION(const SSL_SESSION *in, unsigned char **pp)
ssl_session_oinit(&as.session_id_context, &sid_ctx,
in->sid_ctx, in->sid_ctx_length);
as.time = in->time;
as.timeout = in->timeout;
as.time = (int64_t)in->time;
as.timeout = (int64_t)in->timeout;
as.verify_result = in->verify_result;
as.peer = in->peer;
@ -302,14 +302,15 @@ SSL_SESSION *d2i_SSL_SESSION(SSL_SESSION **a, const unsigned char **pp,
ret->master_key_length = tmpl;
if (as->time != 0)
ret->time = (long)as->time;
ret->time = (time_t)as->time;
else
ret->time = (long)time(NULL);
ret->time = time(NULL);
if (as->timeout != 0)
ret->timeout = (long)as->timeout;
ret->timeout = (time_t)as->timeout;
else
ret->timeout = 3;
ssl_session_calculate_timeout(ret);
X509_free(ret->peer);
ret->peer = as->peer;


+ 7
- 2
ssl/ssl_local.h View File

@ -593,8 +593,10 @@ struct ssl_session_st {
*/
long verify_result; /* only for servers */
CRYPTO_REF_COUNT references;
long timeout;
long time;
time_t timeout;
time_t time;
time_t calc_timeout;
int timeout_ovf;
unsigned int compress_meth; /* Need to lookup the method */
const SSL_CIPHER *cipher;
unsigned long cipher_id; /* when ASN.1 loaded, this needs to be used to
@ -634,6 +636,7 @@ struct ssl_session_st {
unsigned char *ticket_appdata;
size_t ticket_appdata_len;
uint32_t flags;
SSL_CTX *owner;
CRYPTO_RWLOCK *lock;
};
@ -2843,6 +2846,8 @@ int ssl_srp_ctx_init_intern(SSL *s);
int ssl_srp_calc_a_param_intern(SSL *s);
int ssl_srp_server_param_with_username_intern(SSL *s, int *ad);
void ssl_session_calculate_timeout(SSL_SESSION* ss);
# else /* OPENSSL_UNIT_TEST */
# define ssl_init_wbio_buffer SSL_test_functions()->p_ssl_init_wbio_buffer


+ 162
- 45
ssl/ssl_sess.c View File

@ -24,6 +24,58 @@ static void SSL_SESSION_list_remove(SSL_CTX *ctx, SSL_SESSION *s);
static void SSL_SESSION_list_add(SSL_CTX *ctx, SSL_SESSION *s);
static int remove_session_lock(SSL_CTX *ctx, SSL_SESSION *c, int lck);
DEFINE_STACK_OF(SSL_SESSION)
__owur static int sess_timedout(time_t t, SSL_SESSION *ss)
{
/* if timeout overflowed, it can never timeout! */
if (ss->timeout_ovf)
return 0;
return t > ss->calc_timeout;
}
/*
* Returns -1/0/+1 as other XXXcmp-type functions
* Takes overflow of calculated timeout into consideration
*/
__owur static int timeoutcmp(SSL_SESSION *a, SSL_SESSION *b)
{
/* if only one overflowed, then it is greater */
if (a->timeout_ovf && !b->timeout_ovf)
return 1;
if (!a->timeout_ovf && b->timeout_ovf)
return -1;
/* No overflow, or both overflowed, so straight compare is safe */
if (a->calc_timeout < b->calc_timeout)
return -1;
if (a->calc_timeout > b->calc_timeout)
return 1;
return 0;
}
/*
* Calculates effective timeout, saving overflow state
* Locking must be done by the caller of this function
*/
void ssl_session_calculate_timeout(SSL_SESSION *ss)
{
/* Force positive timeout */
if (ss->timeout < 0)
ss->timeout = 0;
ss->calc_timeout = ss->time + ss->timeout;
/*
* |timeout| is always zero or positive, so the check for
* overflow only needs to consider if |time| is positive
*/
ss->timeout_ovf = ss->time > 0 && ss->calc_timeout < ss->time;
/*
* N.B. Realistic overflow can only occur in our lifetimes on a
* 32-bit machine in January 2038.
* However, There are no controls to limit the |timeout|
* value, except to keep it positive.
*/
}
/*
* SSL_get_session() and SSL_get1_session() are problematic in TLS1.3 because,
* unlike in earlier protocol versions, the session ticket may not have been
@ -83,7 +135,8 @@ SSL_SESSION *SSL_SESSION_new(void)
ss->verify_result = 1; /* avoid 0 (= X509_V_OK) just in case */
ss->references = 1;
ss->timeout = 60 * 5 + 4; /* 5 minute timeout by default */
ss->time = (unsigned long)time(NULL);
ss->time = time(NULL);
ssl_session_calculate_timeout(ss);
ss->lock = CRYPTO_THREAD_lock_new();
if (ss->lock == NULL) {
ERR_raise(ERR_LIB_SSL, ERR_R_MALLOC_FAILURE);
@ -587,7 +640,7 @@ int ssl_get_prev_session(SSL *s, CLIENTHELLO_MSG *hello)
goto err;
}
if (ret->timeout < (long)(time(NULL) - ret->time)) { /* timeout */
if (sess_timedout(time(NULL), ret)) {
tsan_counter(&s->session_ctx->stats.sess_timeout);
if (try_session_cache) {
/* session was from the cache, so remove it */
@ -688,9 +741,12 @@ int SSL_CTX_add_session(SSL_CTX *ctx, SSL_SESSION *c)
s = c;
}
/* Put at the head of the queue unless it is already in the cache */
if (s == NULL)
SSL_SESSION_list_add(ctx, c);
/* Adjust last used time, and add back into the cache at the appropriate spot */
if (ctx->session_cache_mode & SSL_SESS_CACHE_UPDATE_TIME) {
c->time = time(NULL);
ssl_session_calculate_timeout(c);
}
SSL_SESSION_list_add(ctx, c);
if (s != NULL) {
/*
@ -832,9 +888,21 @@ int SSL_SESSION_set1_id(SSL_SESSION *s, const unsigned char *sid,
long SSL_SESSION_set_timeout(SSL_SESSION *s, long t)
{
if (s == NULL)
time_t new_timeout = (time_t)t;
if (s == NULL || t < 0)
return 0;
s->timeout = t;
if (s->owner != NULL) {
if (!CRYPTO_THREAD_write_lock(s->owner->lock))
return 0;
s->timeout = new_timeout;
ssl_session_calculate_timeout(s);
SSL_SESSION_list_add(s->owner, s);
CRYPTO_THREAD_unlock(s->owner->lock);
} else {
s->timeout = new_timeout;
ssl_session_calculate_timeout(s);
}
return 1;
}
@ -842,21 +910,33 @@ long SSL_SESSION_get_timeout(const SSL_SESSION *s)
{
if (s == NULL)
return 0;
return s->timeout;
return (long)s->timeout;
}
long SSL_SESSION_get_time(const SSL_SESSION *s)
{
if (s == NULL)
return 0;
return s->time;
return (long)s->time;
}
long SSL_SESSION_set_time(SSL_SESSION *s, long t)
{
time_t new_time = (time_t)t;
if (s == NULL)
return 0;
s->time = t;
if (s->owner != NULL) {
if (!CRYPTO_THREAD_write_lock(s->owner->lock))
return 0;
s->time = new_time;
ssl_session_calculate_timeout(s);
SSL_SESSION_list_add(s->owner, s);
CRYPTO_THREAD_unlock(s->owner->lock);
} else {
s->time = new_time;
ssl_session_calculate_timeout(s);
}
return t;
}
@ -1050,47 +1130,52 @@ int SSL_set_session_ticket_ext(SSL *s, void *ext_data, int ext_len)
return 0;
}
typedef struct timeout_param_st {
SSL_CTX *ctx;
long time;
LHASH_OF(SSL_SESSION) *cache;
} TIMEOUT_PARAM;
static void timeout_cb(SSL_SESSION *s, TIMEOUT_PARAM *p)
{
if ((p->time == 0) || (p->time > (s->time + s->timeout))) { /* timeout */
/*
* The reason we don't call SSL_CTX_remove_session() is to save on
* locking overhead
*/
(void)lh_SSL_SESSION_delete(p->cache, s);
SSL_SESSION_list_remove(p->ctx, s);
s->not_resumable = 1;
if (p->ctx->remove_session_cb != NULL)
p->ctx->remove_session_cb(p->ctx, s);
SSL_SESSION_free(s);
}
}
IMPLEMENT_LHASH_DOALL_ARG(SSL_SESSION, TIMEOUT_PARAM);
void SSL_CTX_flush_sessions(SSL_CTX *s, long t)
{
STACK_OF(SSL_SESSION) *sk;
SSL_SESSION *current;
unsigned long i;
TIMEOUT_PARAM tp;
tp.ctx = s;
tp.cache = s->sessions;
if (tp.cache == NULL)
return;
tp.time = t;
if (!CRYPTO_THREAD_write_lock(s->lock))
return;
sk = sk_SSL_SESSION_new_null();
i = lh_SSL_SESSION_get_down_load(s->sessions);
lh_SSL_SESSION_set_down_load(s->sessions, 0);
lh_SSL_SESSION_doall_TIMEOUT_PARAM(tp.cache, timeout_cb, &tp);
/*
* Iterate over the list from the back (oldest), and stop
* when a session can no longer be removed.
* Add the session to a temporary list to be freed outside
* the SSL_CTX lock.
* But still do the remove_session_cb() within the lock.
*/
while (s->session_cache_tail != NULL) {
current = s->session_cache_tail;
if (t == 0 || sess_timedout((time_t)t, current)) {
lh_SSL_SESSION_delete(s->sessions, current);
SSL_SESSION_list_remove(s, current);
current->not_resumable = 1;
if (s->remove_session_cb != NULL)
s->remove_session_cb(s, current);
/*
* Throw the session on a stack, it's entirely plausible
* that while freeing outside the critical section, the
* session could be re-added, so avoid using the next/prev
* pointers. If the stack failed to create, or the session
* couldn't be put on the stack, just free it here
*/
if (sk == NULL || !sk_SSL_SESSION_push(sk, current))
SSL_SESSION_free(current);
} else {
break;
}
}
lh_SSL_SESSION_set_down_load(s->sessions, i);
CRYPTO_THREAD_unlock(s->lock);
sk_SSL_SESSION_pop_free(sk, SSL_SESSION_free);
}
int ssl_clear_bad_session(SSL *s)
@ -1132,10 +1217,13 @@ static void SSL_SESSION_list_remove(SSL_CTX *ctx, SSL_SESSION *s)
}
}
s->prev = s->next = NULL;
s->owner = NULL;
}
static void SSL_SESSION_list_add(SSL_CTX *ctx, SSL_SESSION *s)
{
SSL_SESSION *next;
if ((s->next != NULL) && (s->prev != NULL))
SSL_SESSION_list_remove(ctx, s);
@ -1145,11 +1233,40 @@ static void SSL_SESSION_list_add(SSL_CTX *ctx, SSL_SESSION *s)
s->prev = (SSL_SESSION *)&(ctx->session_cache_head);
s->next = (SSL_SESSION *)&(ctx->session_cache_tail);
} else {
s->next = ctx->session_cache_head;
s->next->prev = s;
s->prev = (SSL_SESSION *)&(ctx->session_cache_head);
ctx->session_cache_head = s;
if (timeoutcmp(s, ctx->session_cache_head) >= 0) {
/*
* if we timeout after (or the same time as) the first
* session, put us first - usual case
*/
s->next = ctx->session_cache_head;
s->next->prev = s;
s->prev = (SSL_SESSION *)&(ctx->session_cache_head);
ctx->session_cache_head = s;
} else if (timeoutcmp(s, ctx->session_cache_tail) < 0) {
/* if we timeout before the last session, put us last */
s->prev = ctx->session_cache_tail;
s->prev->next = s;
s->next = (SSL_SESSION *)&(ctx->session_cache_tail);
ctx->session_cache_tail = s;
} else {
/*
* we timeout somewhere in-between - if there is only
* one session in the cache it will be caught above
*/
next = ctx->session_cache_head->next;
while (next != (SSL_SESSION*)&(ctx->session_cache_tail)) {
if (timeoutcmp(s, next) >= 0) {
s->next = next;
s->prev = next->prev;
next->prev->next = s;
next->prev = s;
break;
}
next = next->next;
}
}
}
s->owner = ctx;
}
void SSL_CTX_sess_set_new_cb(SSL_CTX *ctx,


+ 2
- 5
ssl/statem/statem_clnt.c View File

@ -2510,11 +2510,8 @@ MSG_PROCESS_RETURN tls_process_new_session_ticket(SSL *s, PACKET *pkt)
s->session = new_sess;
}
/*
* Technically the cast to long here is not guaranteed by the C standard -
* but we use it elsewhere, so this should be ok.
*/
s->session->time = (long)time(NULL);
s->session->time = time(NULL);
ssl_session_calculate_timeout(s->session);
OPENSSL_free(s->session->ext.tick);
s->session->ext.tick = NULL;


+ 3
- 2
ssl/statem/statem_srvr.c View File

@ -3633,7 +3633,7 @@ static int create_ticket_prequel(SSL *s, WPACKET *pkt, uint32_t age_add,
*/
if (!WPACKET_put_bytes_u32(pkt,
(s->hit && !SSL_IS_TLS13(s))
? 0 : s->session->timeout)) {
? 0 : (uint32_t)s->session->timeout)) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
return 0;
}
@ -3930,7 +3930,8 @@ int tls_construct_new_session_ticket(SSL *s, WPACKET *pkt)
}
s->session->master_key_length = hashlen;
s->session->time = (long)time(NULL);
s->session->time = time(NULL);
ssl_session_calculate_timeout(s->session);
if (s->s3.alpn_selected != NULL) {
OPENSSL_free(s->session->ext.alpn_selected);
s->session->ext.alpn_selected =


+ 124
- 0
test/sslapitest.c View File

@ -8122,6 +8122,129 @@ end:
}
#endif /* OPENSSL_NO_TLS1_2 */
static int test_session_timeout(int test)
{
/*
* Test session ordering and timeout
* Can't explicitly test performance of the new code,
* but can test to see if the ordering of the sessions
* are correct, and they they are removed as expected
*/
SSL_SESSION *early = NULL;
SSL_SESSION *middle = NULL;
SSL_SESSION *late = NULL;
SSL_CTX *ctx;
int testresult = 0;
long now = (long)time(NULL);
#define TIMEOUT 10
if (!TEST_ptr(ctx = SSL_CTX_new_ex(libctx, NULL, TLS_method()))
|| !TEST_ptr(early = SSL_SESSION_new())
|| !TEST_ptr(middle = SSL_SESSION_new())
|| !TEST_ptr(late = SSL_SESSION_new()))
goto end;
/* assign unique session ids */
early->session_id_length = SSL3_SSL_SESSION_ID_LENGTH;
memset(early->session_id, 1, SSL3_SSL_SESSION_ID_LENGTH);
middle->session_id_length = SSL3_SSL_SESSION_ID_LENGTH;
memset(middle->session_id, 2, SSL3_SSL_SESSION_ID_LENGTH);
late->session_id_length = SSL3_SSL_SESSION_ID_LENGTH;
memset(late->session_id, 3, SSL3_SSL_SESSION_ID_LENGTH);
if (!TEST_int_eq(SSL_CTX_add_session(ctx, early), 1)
|| !TEST_int_eq(SSL_CTX_add_session(ctx, middle), 1)
|| !TEST_int_eq(SSL_CTX_add_session(ctx, late), 1))
goto end;
/* Make sure they are all added */
if (!TEST_ptr(early->prev)
|| !TEST_ptr(middle->prev)
|| !TEST_ptr(late->prev))
goto end;
if (!TEST_int_ne(SSL_SESSION_set_time(early, now - 10), 0)
|| !TEST_int_ne(SSL_SESSION_set_time(middle, now), 0)
|| !TEST_int_ne(SSL_SESSION_set_time(late, now + 10), 0))
goto end;
if (!TEST_int_ne(SSL_SESSION_set_timeout(early, TIMEOUT), 0)
|| !TEST_int_ne(SSL_SESSION_set_timeout(middle, TIMEOUT), 0)
|| !TEST_int_ne(SSL_SESSION_set_timeout(late, TIMEOUT), 0))
goto end;
/* Make sure they are all still there */
if (!TEST_ptr(early->prev)
|| !TEST_ptr(middle->prev)
|| !TEST_ptr(late->prev))
goto end;
/* Make sure they are in the expected order */
if (!TEST_ptr_eq(late->next, middle)
|| !TEST_ptr_eq(middle->next, early)
|| !TEST_ptr_eq(early->prev, middle)
|| !TEST_ptr_eq(middle->prev, late))
goto end;
/* This should remove "early" */
SSL_CTX_flush_sessions(ctx, now + TIMEOUT - 1);
if (!TEST_ptr_null(early->prev)
|| !TEST_ptr(middle->prev)
|| !TEST_ptr(late->prev))
goto end;
/* This should remove "middle" */
SSL_CTX_flush_sessions(ctx, now + TIMEOUT + 1);
if (!TEST_ptr_null(early->prev)
|| !TEST_ptr_null(middle->prev)
|| !TEST_ptr(late->prev))
goto end;
/* This should remove "late" */
SSL_CTX_flush_sessions(ctx, now + TIMEOUT + 11);
if (!TEST_ptr_null(early->prev)
|| !TEST_ptr_null(middle->prev)
|| !TEST_ptr_null(late->prev))
goto end;
/* Add them back in again */
if (!TEST_int_eq(SSL_CTX_add_session(ctx, early), 1)
|| !TEST_int_eq(SSL_CTX_add_session(ctx, middle), 1)
|| !TEST_int_eq(SSL_CTX_add_session(ctx, late), 1))
goto end;
/* Make sure they are all added */
if (!TEST_ptr(early->prev)
|| !TEST_ptr(middle->prev)
|| !TEST_ptr(late->prev))
goto end;
/* This should remove all of them */
SSL_CTX_flush_sessions(ctx, 0);
if (!TEST_ptr_null(early->prev)
|| !TEST_ptr_null(middle->prev)
|| !TEST_ptr_null(late->prev))
goto end;
(void)SSL_CTX_set_session_cache_mode(ctx, SSL_SESS_CACHE_UPDATE_TIME
| SSL_CTX_get_session_cache_mode(ctx));
/* make sure |now| is NOT equal to the current time */
now -= 10;
if (!TEST_int_ne(SSL_SESSION_set_time(early, now), 0)
|| !TEST_int_eq(SSL_CTX_add_session(ctx, early), 1)
|| !TEST_long_ne(SSL_SESSION_get_time(early), now))
goto end;
testresult = 1;
end:
SSL_CTX_free(ctx);
SSL_SESSION_free(early);
SSL_SESSION_free(middle);
SSL_SESSION_free(late);
return testresult;
}
/*
* Test 0: Client sets servername and server acknowledges it (TLSv1.2)
* Test 1: Client sets servername and server does not acknowledge it (TLSv1.2)
@ -9287,6 +9410,7 @@ int setup_tests(void)
#endif
ADD_TEST(test_inherit_verify_param);
ADD_TEST(test_set_alpn);
ADD_ALL_TESTS(test_session_timeout, 1);
return 1;
err:


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