From: Peter Xu Date: Thu, 18 Sep 2025 20:39:36 +0000 (-0400) Subject: io/crypto: Move tls premature termination handling into QIO layer X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=7e0c22d585581b8083ffdeb332ea497218665daf;p=thirdparty%2Fqemu.git io/crypto: Move tls premature termination handling into QIO layer QCryptoTLSSession allows TLS premature termination in two cases, one of the case is when the channel shutdown() is invoked on READ side. It's possible the shutdown() happened after the read thread blocked at gnutls_record_recv(). In this case, we should allow the premature termination to happen. The problem is by the time qcrypto_tls_session_read() was invoked, tioc->shutdown may not have been set, so this may instead be treated as an error if there is concurrent shutdown() calls. To allow the flag to reflect the latest status of tioc->shutdown, move the check upper into the QIOChannel level, so as to read the flag only after QEMU gets an GNUTLS_E_PREMATURE_TERMINATION. When at it, introduce qio_channel_tls_allow_premature_termination() helper to make the condition checks easier to read. When doing so, change the qatomic_load_acquire() to qatomic_read(): here we don't need any ordering of memory accesses, but reading a flag. qatomic_read() would suffice because it guarantees fetching from memory. Nothing else we should need to order on memory access. This patch will fix a qemu qtest warning when running the preempt tls test, reporting premature termination: QTEST_QEMU_BINARY=./qemu-system-x86_64 ./tests/qtest/migration-test --full -r /x86_64/migration/postcopy/preempt/tls/psk ... qemu-kvm: Cannot read from TLS channel: The TLS connection was non-properly terminated. ... In this specific case, the error was set by postcopy_preempt_thread, which normally will be concurrently shutdown()ed by the main thread. Reviewed-by: Daniel P. Berrangé Reviewed-by: Juraj Marcin Reviewed-by: Fabiano Rosas Link: https://lore.kernel.org/r/20250918203937.200833-2-peterx@redhat.com Signed-off-by: Peter Xu --- diff --git a/crypto/tlssession.c b/crypto/tlssession.c index 86d407a1429..ac38c2121db 100644 --- a/crypto/tlssession.c +++ b/crypto/tlssession.c @@ -552,7 +552,6 @@ ssize_t qcrypto_tls_session_read(QCryptoTLSSession *session, char *buf, size_t len, - bool gracefulTermination, Error **errp) { ssize_t ret; @@ -570,9 +569,8 @@ qcrypto_tls_session_read(QCryptoTLSSession *session, if (ret < 0) { if (ret == GNUTLS_E_AGAIN) { return QCRYPTO_TLS_SESSION_ERR_BLOCK; - } else if ((ret == GNUTLS_E_PREMATURE_TERMINATION) && - gracefulTermination){ - return 0; + } else if (ret == GNUTLS_E_PREMATURE_TERMINATION) { + return QCRYPTO_TLS_SESSION_PREMATURE_TERMINATION; } else { if (session->rerr) { error_propagate(errp, session->rerr); @@ -789,7 +787,6 @@ ssize_t qcrypto_tls_session_read(QCryptoTLSSession *sess, char *buf, size_t len, - bool gracefulTermination, Error **errp) { error_setg(errp, "TLS requires GNUTLS support"); diff --git a/include/crypto/tlssession.h b/include/crypto/tlssession.h index 2f62ce2d67a..2e9fe11cf6e 100644 --- a/include/crypto/tlssession.h +++ b/include/crypto/tlssession.h @@ -110,6 +110,7 @@ typedef struct QCryptoTLSSession QCryptoTLSSession; #define QCRYPTO_TLS_SESSION_ERR_BLOCK -2 +#define QCRYPTO_TLS_SESSION_PREMATURE_TERMINATION -3 /** * qcrypto_tls_session_new: @@ -259,7 +260,6 @@ ssize_t qcrypto_tls_session_write(QCryptoTLSSession *sess, * @sess: the TLS session object * @buf: to fill with plain text received * @len: the length of @buf - * @gracefulTermination: treat premature termination as graceful EOF * @errp: pointer to hold returned error object * * Receive up to @len bytes of data from the remote peer @@ -267,22 +267,18 @@ ssize_t qcrypto_tls_session_write(QCryptoTLSSession *sess, * qcrypto_tls_session_set_callbacks(), decrypt it and * store it in @buf. * - * If @gracefulTermination is true, then a premature termination - * of the TLS session will be treated as indicating EOF, as - * opposed to an error. - * * It is an error to call this before * qcrypto_tls_session_handshake() returns * QCRYPTO_TLS_HANDSHAKE_COMPLETE * * Returns: the number of bytes received, * or QCRYPTO_TLS_SESSION_ERR_BLOCK if the receive would block, - * or -1 on error. + * or QCRYPTO_TLS_SESSION_PREMATURE_TERMINATION if a premature termination + * is detected, or -1 on error. */ ssize_t qcrypto_tls_session_read(QCryptoTLSSession *sess, char *buf, size_t len, - bool gracefulTermination, Error **errp); /** diff --git a/io/channel-tls.c b/io/channel-tls.c index 7135896f791..1fbed4be0c6 100644 --- a/io/channel-tls.c +++ b/io/channel-tls.c @@ -346,6 +346,19 @@ static void qio_channel_tls_finalize(Object *obj) qcrypto_tls_session_free(ioc->session); } +static bool +qio_channel_tls_allow_premature_termination(QIOChannelTLS *tioc, int flags) +{ + if (flags & QIO_CHANNEL_READ_FLAG_RELAXED_EOF) { + return true; + } + + if (qatomic_read(&tioc->shutdown) & QIO_CHANNEL_SHUTDOWN_READ) { + return true; + } + + return false; +} static ssize_t qio_channel_tls_readv(QIOChannel *ioc, const struct iovec *iov, @@ -364,8 +377,6 @@ static ssize_t qio_channel_tls_readv(QIOChannel *ioc, tioc->session, iov[i].iov_base, iov[i].iov_len, - flags & QIO_CHANNEL_READ_FLAG_RELAXED_EOF || - qatomic_load_acquire(&tioc->shutdown) & QIO_CHANNEL_SHUTDOWN_READ, errp); if (ret == QCRYPTO_TLS_SESSION_ERR_BLOCK) { if (got) { @@ -373,6 +384,12 @@ static ssize_t qio_channel_tls_readv(QIOChannel *ioc, } else { return QIO_CHANNEL_ERR_BLOCK; } + } else if (ret == QCRYPTO_TLS_SESSION_PREMATURE_TERMINATION) { + if (qio_channel_tls_allow_premature_termination(tioc, flags)) { + ret = 0; + } else { + return -1; + } } else if (ret < 0) { return -1; }