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56 lines
2.2 KiB
56 lines
2.2 KiB
9 months ago
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From bdb1ca45454d90410031c4c2054005a995f76180 Mon Sep 17 00:00:00 2001
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From: Zdenek Dohnal <zdohnal@redhat.com>
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Date: Wed, 6 Apr 2022 15:04:45 +0200
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Subject: [PATCH] cups/tls-gnutls.c: Use always GNUTLS_SHUT_WR
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The current mode for `gnutls_bye()` in client use cases strictly
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follows TLS v1.2 standard, which in this particular part says:
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```
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Unless some other fatal alert has been transmitted, each party is
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required to send a close_notify alert before closing the write
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side of the connection. The other party MUST respond with a
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close_notify alert of its own and close down the connection immediately,
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discarding any pending writes. It is not required for the initiator
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of the close to wait for the responding close_notify alert before
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closing the read side of the connection.
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```
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and waits for the other side of TLS connection to confirm the close.
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Unfortunately it can undesired for reasons:
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- we support switching of TLS versions in CUPS, and this mode strictly
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follows TLS v1.2 - so for older version this behavior is not expected
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and can cause delays
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- even some TLS v1.2 implementations (like Windows Server 2016) don't
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comply TLS v1.2 behavior even if it says it does - in that case,
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encrypted printing takes 30s till HTTP timeout is reached, because the
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other side didn't send confirmation
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- AFAIU openssl's SSL_shutdown() doesn't make this TLS v1.2 difference,
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so we could end up with two TLS implementations in CUPS which will
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behave differently
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Since the standard defines that waiting for confirmation is not required
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and due the problems above, I would propose using GNUTLS_SHUT_WR mode
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regardless of HTTP mode.
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---
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cups/tls-gnutls.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/cups/tls-gnutls.c b/cups/tls-gnutls.c
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index c55995b2b..f87b4f4df 100644
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--- a/cups/tls-gnutls.c
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+++ b/cups/tls-gnutls.c
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@@ -1667,7 +1667,7 @@ _httpTLSStop(http_t *http) /* I - Connection to server */
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int error; /* Error code */
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- error = gnutls_bye(http->tls, http->mode == _HTTP_MODE_CLIENT ? GNUTLS_SHUT_RDWR : GNUTLS_SHUT_WR);
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+ error = gnutls_bye(http->tls, GNUTLS_SHUT_WR);
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if (error != GNUTLS_E_SUCCESS)
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_cupsSetError(IPP_STATUS_ERROR_INTERNAL, gnutls_strerror(errno), 0);
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--
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2.35.1
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