Date: Wed, 16 Feb 2022 16:52:44 GMT From: Mark Johnston <markj@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: e3b852f99bc5 - stable/13 - ktls: Disallow transmitting empty frames outside of TLS 1.0/CBC mode Message-ID: <202202161652.21GGqi6j068526@gitrepo.freebsd.org>
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The branch stable/13 has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=e3b852f99bc5f51e99f8fda67e71ab3639f60f4e commit e3b852f99bc5f51e99f8fda67e71ab3639f60f4e Author: Mark Johnston <markj@FreeBSD.org> AuthorDate: 2022-02-08 17:36:41 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2022-02-16 16:52:31 +0000 ktls: Disallow transmitting empty frames outside of TLS 1.0/CBC mode There was nothing preventing one from sending an empty fragment on an arbitrary KTLS TX-enabled socket, but ktls_frame() asserts that this could not happen. Though the transmit path handles this case for TLS 1.0 with AES-CBC, we should be strict and allow empty fragments only in modes where it is explicitly allowed. Modify sosend_generic() to reject writes to a KTLS-enabled socket if the number of data bytes is zero, so that userspace cannot trigger the aforementioned assertion. Add regression tests to exercise this case. Reported by: syzkaller Reviewed by: gallatin, jhb Sponsored by: The FreeBSD Foundation (cherry picked from commit 5de79eeddb9de079d108d1312148bcbefce45c27) --- sys/kern/uipc_ktls.c | 18 ++++++++++++------ sys/kern/uipc_socket.c | 5 +++++ sys/sys/ktls.h | 1 + tests/sys/kern/ktls_test.c | 31 +++++++++++++++++++++++-------- 4 files changed, 41 insertions(+), 14 deletions(-) diff --git a/sys/kern/uipc_ktls.c b/sys/kern/uipc_ktls.c index db4ab69e06cf..50bd0a0df21e 100644 --- a/sys/kern/uipc_ktls.c +++ b/sys/kern/uipc_ktls.c @@ -1568,19 +1568,18 @@ ktls_frame(struct mbuf *top, struct ktls_session *tls, int *enq_cnt, * All mbufs in the chain should be TLS records whose * payload does not exceed the maximum frame length. * - * Empty TLS records are permitted when using CBC. + * Empty TLS 1.0 records are permitted when using CBC. */ - KASSERT(m->m_len <= maxlen && - (tls->params.cipher_algorithm == CRYPTO_AES_CBC ? - m->m_len >= 0 : m->m_len > 0), - ("ktls_frame: m %p len %d\n", m, m->m_len)); + KASSERT(m->m_len <= maxlen && m->m_len >= 0 && + (m->m_len > 0 || ktls_permit_empty_frames(tls)), + ("ktls_frame: m %p len %d", m, m->m_len)); /* * TLS frames require unmapped mbufs to store session * info. */ KASSERT((m->m_flags & M_EXTPG) != 0, - ("ktls_frame: mapped mbuf %p (top = %p)\n", m, top)); + ("ktls_frame: mapped mbuf %p (top = %p)", m, top)); tls_len = m->m_len; @@ -1674,6 +1673,13 @@ ktls_frame(struct mbuf *top, struct ktls_session *tls, int *enq_cnt, } } +bool +ktls_permit_empty_frames(struct ktls_session *tls) +{ + return (tls->params.cipher_algorithm == CRYPTO_AES_CBC && + tls->params.tls_vminor == TLS_MINOR_VER_ZERO); +} + void ktls_check_rx(struct sockbuf *sb) { diff --git a/sys/kern/uipc_socket.c b/sys/kern/uipc_socket.c index 1fd63640988b..5a3748eb8cf5 100644 --- a/sys/kern/uipc_socket.c +++ b/sys/kern/uipc_socket.c @@ -1604,6 +1604,11 @@ sosend_generic(struct socket *so, struct sockaddr *addr, struct uio *uio, atomic = 1; } } + + if (resid == 0 && !ktls_permit_empty_frames(tls)) { + error = EINVAL; + goto release; + } } #endif diff --git a/sys/sys/ktls.h b/sys/sys/ktls.h index e9cae34035c6..0e16fd5d9d1e 100644 --- a/sys/sys/ktls.h +++ b/sys/sys/ktls.h @@ -223,6 +223,7 @@ int ktls_enable_tx(struct socket *so, struct tls_enable *en); void ktls_destroy(struct ktls_session *tls); void ktls_frame(struct mbuf *m, struct ktls_session *tls, int *enqueue_cnt, uint8_t record_type); +bool ktls_permit_empty_frames(struct ktls_session *tls); void ktls_seq(struct sockbuf *sb, struct mbuf *m); void ktls_enqueue(struct mbuf *m, struct socket *so, int page_count); void ktls_enqueue_to_free(struct mbuf *m); diff --git a/tests/sys/kern/ktls_test.c b/tests/sys/kern/ktls_test.c index b2c722914854..a994f675711b 100644 --- a/tests/sys/kern/ktls_test.c +++ b/tests/sys/kern/ktls_test.c @@ -1057,9 +1057,19 @@ test_ktls_transmit_empty_fragment(struct tls_enable *en, uint64_t seqno) fd_set_blocking(sockets[0]); fd_set_blocking(sockets[1]); - /* A write of zero bytes should send an empty fragment. */ + /* + * A write of zero bytes should send an empty fragment only for + * TLS 1.0, otherwise an error should be raised. + */ rv = write(sockets[1], NULL, 0); - ATF_REQUIRE(rv == 0); + if (rv == 0) { + ATF_REQUIRE(en->cipher_algorithm == CRYPTO_AES_CBC); + ATF_REQUIRE(en->tls_vminor == TLS_MINOR_VER_ZERO); + } else { + ATF_REQUIRE(rv == -1); + ATF_REQUIRE(errno == EINVAL); + goto out; + } /* * First read the header to determine how much additional data @@ -1081,6 +1091,7 @@ test_ktls_transmit_empty_fragment(struct tls_enable *en, uint64_t seqno) "read %zd decrypted bytes for an empty fragment", rv); ATF_REQUIRE(record_type == TLS_RLTYPE_APP); +out: free(outbuf); ATF_REQUIRE(close(sockets[1]) == 0); @@ -1324,7 +1335,7 @@ ATF_TC_BODY(ktls_transmit_##cipher_name##_##name, tc) \ ATF_TP_ADD_TC(tp, ktls_transmit_##cipher_name##_##name); #define GEN_TRANSMIT_EMPTY_FRAGMENT_TEST(cipher_name, cipher_alg, \ - key_size, auth_alg) \ + key_size, auth_alg, minor) \ ATF_TC_WITHOUT_HEAD(ktls_transmit_##cipher_name##_empty_fragment); \ ATF_TC_BODY(ktls_transmit_##cipher_name##_empty_fragment, tc) \ { \ @@ -1333,14 +1344,14 @@ ATF_TC_BODY(ktls_transmit_##cipher_name##_empty_fragment, tc) \ \ ATF_REQUIRE_KTLS(); \ seqno = random(); \ - build_tls_enable(cipher_alg, key_size, auth_alg, \ - TLS_MINOR_VER_ZERO, seqno, &en); \ + build_tls_enable(cipher_alg, key_size, auth_alg, minor, seqno, \ + &en); \ test_ktls_transmit_empty_fragment(&en, seqno); \ free_tls_enable(&en); \ } #define ADD_TRANSMIT_EMPTY_FRAGMENT_TEST(cipher_name, cipher_alg, \ - key_size, auth_alg) \ + key_size, auth_alg, minor) \ ATF_TP_ADD_TC(tp, ktls_transmit_##cipher_name##_empty_fragment); #define GEN_TRANSMIT_TESTS(cipher_name, cipher_alg, key_size, auth_alg, \ @@ -1461,7 +1472,9 @@ AES_CBC_TESTS(GEN_TRANSMIT_PADDING_TESTS); * Test "empty fragments" which are TLS records with no payload that * OpenSSL can send for TLS 1.0 connections. */ -TLS_10_TESTS(GEN_TRANSMIT_EMPTY_FRAGMENT_TEST); +AES_CBC_TESTS(GEN_TRANSMIT_EMPTY_FRAGMENT_TEST); +AES_GCM_TESTS(GEN_TRANSMIT_EMPTY_FRAGMENT_TEST); +CHACHA20_TESTS(GEN_TRANSMIT_EMPTY_FRAGMENT_TEST); static void test_ktls_invalid_transmit_cipher_suite(struct tls_enable *en) @@ -1708,7 +1721,9 @@ ATF_TP_ADD_TCS(tp) AES_GCM_TESTS(ADD_TRANSMIT_TESTS); CHACHA20_TESTS(ADD_TRANSMIT_TESTS); AES_CBC_TESTS(ADD_TRANSMIT_PADDING_TESTS); - TLS_10_TESTS(ADD_TRANSMIT_EMPTY_FRAGMENT_TEST); + AES_CBC_TESTS(ADD_TRANSMIT_EMPTY_FRAGMENT_TEST); + AES_GCM_TESTS(ADD_TRANSMIT_EMPTY_FRAGMENT_TEST); + CHACHA20_TESTS(ADD_TRANSMIT_EMPTY_FRAGMENT_TEST); INVALID_CIPHER_SUITES(ADD_INVALID_TRANSMIT_TEST); /* Receive tests */
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