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Fix session ticket key rotation when hint exceeds key lifetime #10822

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Fix session ticket key rotation when hint exceeds key lifetime #10822

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11 changes: 11 additions & 0 deletions src/ssl_api_ext.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1055,6 +1055,8 @@ int wolfSSL_CTX_set_TicketEncCb(WOLFSSL_CTX* ctx, SessionTicketEncCb cb)
*
* @param [in] ctx SSL/TLS context object.
* @param [in] hint Lifetime hint in seconds. No more than 604800 (7 days).
* With the default ticket encryption callback, must also be
* less than WOLFSSL_TICKET_KEY_LIFETIME / 2.
* @return WOLFSSL_SUCCESS on success.
* @return BAD_FUNC_ARG when ctx is NULL or hint is out of range.
*/
Expand All @@ -1068,6 +1070,15 @@ int wolfSSL_CTX_set_TicketHint(WOLFSSL_CTX* ctx, int hint)
if (hint < 0 || hint > 604800)
return BAD_FUNC_ARG;

#ifdef WOLFSSL_TICKET_KEY_LIFETIME
/* The default ticket encryption callback rotates two keys, each living
* WOLFSSL_TICKET_KEY_LIFETIME seconds. Its staggered rotation can only
* honor a hint below half that; a larger hint would leave no key available
* for encryption. */
if (hint >= WOLFSSL_TICKET_KEY_LIFETIME / 2)
return BAD_FUNC_ARG;
#endif

ctx->ticketHint = hint;

return WOLFSSL_SUCCESS;
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11 changes: 11 additions & 0 deletions tests/api/test_ssl_ext.c
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Expand Up @@ -188,7 +188,18 @@ int test_wolfSSL_CTX_set_TicketHint_ext(void)
ExpectIntEQ(wolfSSL_CTX_set_TicketHint(ctx, 604801),
WC_NO_ERR_TRACE(BAD_FUNC_ARG));
ExpectIntEQ(wolfSSL_CTX_set_TicketHint(ctx, 0), WOLFSSL_SUCCESS);
#ifdef WOLFSSL_TICKET_KEY_LIFETIME
/* The default ticket encryption callback can only honor a hint below half
* the ticket key lifetime; larger values are rejected. */
ExpectIntEQ(wolfSSL_CTX_set_TicketHint(ctx, WOLFSSL_TICKET_KEY_LIFETIME / 2),
WC_NO_ERR_TRACE(BAD_FUNC_ARG));
ExpectIntEQ(wolfSSL_CTX_set_TicketHint(ctx,
WOLFSSL_TICKET_KEY_LIFETIME / 2 - 1), WOLFSSL_SUCCESS);
ExpectIntEQ(wolfSSL_CTX_set_TicketHint(ctx, 604800),
WC_NO_ERR_TRACE(BAD_FUNC_ARG));
#else
ExpectIntEQ(wolfSSL_CTX_set_TicketHint(ctx, 604800), WOLFSSL_SUCCESS);
#endif

wolfSSL_CTX_free(ctx);
#endif
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4 changes: 2 additions & 2 deletions wolfssl/internal.h
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Expand Up @@ -2047,8 +2047,8 @@ WOLFSSL_LOCAL int NamedGroupIsPqcHybrid(int group);
/* Default lifetime is 1 hour from issue of first ticket with key. */
#define WOLFSSL_TICKET_KEY_LIFETIME (60 * 60)
#endif
#if WOLFSSL_TICKET_KEY_LIFETIME <= SESSION_TICKET_HINT_DEFAULT
#error "Ticket Key lifetime must be longer than ticket life hint."
#if WOLFSSL_TICKET_KEY_LIFETIME <= 2 * SESSION_TICKET_HINT_DEFAULT
#error "Ticket Key lifetime must be more than twice the ticket life hint."
#endif
#endif

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