mutualVersion takes a maximum version, but skips TLS 1.3 because this
version is not negotiated via ClientHello.legacy_version. The server
however still uses its ServerHello.version field to select a version
from the supported_versions extension and the client must do the same.
A new getSupportedVersions method is introduced to have a single place
to handle the mapping of VersionTLS13 to the draft values.
Remove the MaxVersion override to TLS 1.3, users must set MaxVersion if
they intent to use the experimental TLS 1.3 functionality.
Fixes: ("crypto/tls: make 1.3 version negotiation more robust")
To allow clients to advertise both TLS 1.2 and TLS 1.3 cipher suites,
remove the distinction between both suites. TLS 1.3 suites are now
always included in the default cipher list (and the client will send it
if MaxVersion allows for it).
Since TLS 1.3 is expected to become the default MaxVersion and
applications might have set only TLS 1.2 cipher suites in their
configuration, TLS 1.3 cipher suites are added when none are present.
Alternatively, I considered disallowing overriding the TLS 1.3 suites,
but that requires more complexity and has not much benefits. Provide a
mechanism and do not dictate policy, application developers might want
to fix a cipher suite for testing other implementations for example.
Fixes https://github.com/cloudflare/tls-tris/pull/22
Phase should only be accessed under in.Mutex. Handshake and all Read
operations obtain that lock. However, many functions checking for
handshakeRunning only obtain handshakeMutex: reintroduce
handshakeCompleted for them. ConnectionState and Close check for
handshakeConfirmed, introduce an atomic flag for them.
I opted for adding a separate TLS13CipherSuites field to the Config
because library users that did not set Config.MaxVersion are
supposed to get TLS 1.3 support automatically, like it has been for
HTTP/2, but having set CipherSuites would effectively disable it.
Updates #9671
Change-Id: I26a2776b68374d6f5ee45629da09f9494fe723ad
SNI values may not include a trailing dot according to
https://tools.ietf.org/html/rfc6066#section-3. Although crypto/tls
handled this correctly as a client, it didn't reject this as a server.
This change makes sending an SNI value with a trailing dot a fatal
error.
Updates #18114.
Change-Id: Ib7897ab40e98d4a7a4646ff8469a55233621f631
Reviewed-on: https://go-review.googlesource.com/33904
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Fix spelling of "original" and "occurred" in new gofmt docs. The same
misspelling of "occurred" was also present in crypto/tls, I fixed it there as
well.
Change-Id: I67b4f1c09bd1a2eb1844207d5514f08a9f525ff9
Reviewed-on: https://go-review.googlesource.com/33138
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Currently, the selection of a client certificate done internally based
on the limitations given by the server's request and the certifcates in
the Config. This means that it's not possible for an application to
control that selection based on details of the request.
This change adds a callback, GetClientCertificate, that is called by a
Client during the handshake and which allows applications to select the
best certificate at that time.
(Based on https://golang.org/cl/25570/ by Bernd Fix.)
Fixes#16626.
Change-Id: Ia4cea03235d2aa3c9fd49c99c227593c8e86ddd9
Reviewed-on: https://go-review.googlesource.com/32115
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
VerifyPeerCertificate returns an error if the peer should not be
trusted. It will be called after the initial handshake and before
any other verification checks on the cert or chain are performed.
This provides the callee an opportunity to augment the certificate
verification.
If VerifyPeerCertificate is not nil and returns an error,
then the handshake will fail.
Fixes#16363
Change-Id: I6a22f199f0e81b6f5d5f37c54d85ab878216bb22
Reviewed-on: https://go-review.googlesource.com/26654
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Since there's no aspect of key logging that OpenSSL can check for us,
the tests for it might as well just connect to another goroutine as this
is lower-maintainance.
Change-Id: I746d1dbad1b4bbfc8ef6ccf136ee4824dbda021e
Reviewed-on: https://go-review.googlesource.com/30089
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Joonas Kuorilehto <joneskoo@derbian.fi>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Add support for writing TLS client random and master secret
in NSS key log format.
https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/Key_Log_Format
Normally this is enabled by a developer debugging TLS based
applications, especially HTTP/2, by setting the KeyLogWriter
to an open file. The keys negotiated in handshake are then
logged and can be used to decrypt TLS sessions e.g. in Wireshark.
Applications may choose to add support similar to NSS where this
is enabled by environment variable, but no such mechanism is
built in to Go. Instead each application must explicitly enable.
Fixes#13057.
Change-Id: If6edd2d58999903e8390b1674ba4257ecc747ae1
Reviewed-on: https://go-review.googlesource.com/27434
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This change causes TLS handshake messages to be buffered and written in
a single Write to the underlying net.Conn.
There are two reasons to want to do this:
Firstly, it's slightly preferable to do this in order to save sending
several, small packets over the network where a single one will do.
Secondly, since 37c28759ca46cf381a466e32168a793165d9c9e9 errors from
Write have been returned from a handshake. This means that, if a peer
closes the connection during a handshake, a “broken pipe” error may
result from tls.Conn.Handshake(). This can mask any, more detailed,
fatal alerts that the peer may have sent because a read will never
happen.
Buffering handshake messages means that the peer will not receive, and
possibly reject, any of a flow while it's still being written.
Fixes#15709
Change-Id: I38dcff1abecc06e52b2de647ea98713ce0fb9a21
Reviewed-on: https://go-review.googlesource.com/23609
Reviewed-by: Andrew Gerrand <adg@golang.org>
Run-TryBot: Andrew Gerrand <adg@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This change adds Config.Renegotiation which controls whether a TLS
client will accept renegotiation requests from a server. This is used,
for example, by some web servers that wish to “add” a client certificate
to an HTTPS connection.
This is disabled by default because it significantly complicates the
state machine.
Originally, handshakeMutex was taken before locking either Conn.in or
Conn.out. However, if renegotiation is permitted then a handshake may
be triggered during a Read() call. If Conn.in were unlocked before
taking handshakeMutex then a concurrent Read() call could see an
intermediate state and trigger an error. Thus handshakeMutex is now
locked after Conn.in and the handshake functions assume that Conn.in is
locked for the duration of the handshake.
Additionally, handshakeMutex used to protect Conn.out also. With the
possibility of renegotiation that's no longer viable and so
writeRecordLocked has been split off.
Fixes#5742.
Change-Id: I935914db1f185d507ff39bba8274c148d756a1c8
Reviewed-on: https://go-review.googlesource.com/22475
Run-TryBot: Adam Langley <agl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Error strings in this package were all over the place: some were
prefixed with “tls:”, some with “crypto/tls:” and some didn't have a
prefix.
This change makes everything use the prefix “tls:”.
Change-Id: Ie8b073c897764b691140412ecd6613da8c4e33a2
Reviewed-on: https://go-review.googlesource.com/21893
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Per RFC 5246, 7.4.1.3:
cipher_suite
The single cipher suite selected by the server from the list in
ClientHello.cipher_suites. For resumed sessions, this field is
the value from the state of the session being resumed.
The specifications are not very clearly written about resuming sessions
at the wrong version (i.e. is the TLS 1.0 notion of "session" the same
type as the TLS 1.1 notion of "session"?). But every other
implementation enforces this check and not doing so has some odd
semantics.
Change-Id: I6234708bd02b636c25139d83b0d35381167e5cad
Reviewed-on: https://go-review.googlesource.com/21153
Reviewed-by: Adam Langley <agl@golang.org>
This promotes a connection hang during TLS handshake to a proper error.
This doesn't fully address #14539 because the error reported in that
case is a write-on-socket-not-connected error, which implies that an
earlier error during connection setup is not being checked, but it is
an improvement over the current behaviour.
Updates #14539.
Change-Id: I0571a752d32d5303db48149ab448226868b19495
Reviewed-on: https://go-review.googlesource.com/19990
Reviewed-by: Adam Langley <agl@golang.org>
This is a followup change to #13111 for filtering out IPv6 literals and
absolute FQDNs from being as the SNI values.
Updates #13111.
Fixes#14404.
Change-Id: I09ab8d2a9153d9a92147e57ca141f2e97ddcef6e
Reviewed-on: https://go-review.googlesource.com/19704
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
During the TLS handshake, check the cipher suite the server selects is
one of those offered in the ClientHello. The code was checking it was
in the larger list that was sometimes whittled down for the ClientHello.
Fixes#13174
Change-Id: Iad8eebbcfa5027f30403b9700c43cfa949e135bb
Reviewed-on: https://go-review.googlesource.com/16698
Reviewed-by: Adam Langley <agl@golang.org>
Run-TryBot: Adam Langley <agl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
(This relands commit a4dcc692011bf1ceca9b1a363fd83f3e59e399ee.)
https://tools.ietf.org/html/rfc6066#section-3 states:
“Literal IPv4 and IPv6 addresses are not permitted in "HostName".”
However, if an IP literal was set as Config.ServerName (which could
happen as easily as calling Dial with an IP address) then the code would
send the IP literal as the SNI value.
This change filters out IP literals, as recognised by net.ParseIP, from
being sent as the SNI value.
Fixes#13111.
Change-Id: I6e544a78a01388f8fe98150589d073b917087f75
Reviewed-on: https://go-review.googlesource.com/16776
Run-TryBot: Adam Langley <agl@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
https://tools.ietf.org/html/rfc6066#section-3 states:
“Literal IPv4 and IPv6 addresses are not permitted in "HostName".”
However, if an IP literal was set as Config.ServerName (which could
happen as easily as calling Dial with an IP address) then the code would
send the IP literal as the SNI value.
This change filters out IP literals, as recognised by net.ParseIP, from
being sent as the SNI value.
Fixes#13111.
Change-Id: Ie9ec7acc767ae172b48c9c6dd8d84fa27b1cf0de
Reviewed-on: https://go-review.googlesource.com/16742
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Adam Langley <agl@golang.org>
Strengthening VerifyHostname exposed the fact that for resumed
connections, ConnectionState().VerifiedChains was not being saved
and restored during the ClientSessionCache operations.
Do that.
This change just saves the verified chains in the client's session
cache. It does not re-verify the certificates when resuming a
connection.
There are arguments both ways about this: we want fast, light-weight
resumption connections (thus suggesting that we shouldn't verify) but
it could also be a little surprising that, if the verification config
is changed, that would be ignored if the same session cache is used.
On the server side we do re-verify client-auth certificates, but the
situation is a little different there. The client session cache is an
object in memory that's reset each time the process restarts. But the
server's session cache is a conceptual object, held by the clients, so
can persist across server restarts. Thus the chance of a change in
verification config being surprisingly ignored is much higher in the
server case.
Fixes#12024.
Change-Id: I3081029623322ce3d9f4f3819659fdd9a381db16
Reviewed-on: https://go-review.googlesource.com/13164
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Adam Langley <agl@golang.org>
Prior to TLS 1.2, the handshake had a pleasing property that one could
incrementally hash it and, from that, get the needed hashes for both
the CertificateVerify and Finished messages.
TLS 1.2 introduced negotiation for the signature and hash and it became
possible for the handshake hash to be, say, SHA-384, but for the
CertificateVerify to sign the handshake with SHA-1. The problem is that
one doesn't know in advance which hashes will be needed and thus the
handshake needs to be buffered.
Go ignored this, always kept a single handshake hash, and any signatures
over the handshake had to use that hash.
However, there are a set of servers that inspect the client's offered
signature hash functions and will abort the handshake if one of the
server's certificates is signed with a hash function outside of that
set. https://robertsspaceindustries.com/ is an example of such a server.
Clearly not a lot of thought happened when that server code was written,
but its out there and we have to deal with it.
This change decouples the handshake hash from the CertificateVerify
hash. This lays the groundwork for advertising support for SHA-384 but
doesn't actually make that change in the interests of reviewability.
Updating the advertised hash functions will cause changes in many of the
testdata/ files and some errors might get lost in the noise. This change
only needs to update four testdata/ files: one because a SHA-384-based
handshake is now being signed with SHA-256 and the others because the
TLS 1.2 CertificateRequest message now includes SHA-1.
This change also has the effect of adding support for
client-certificates in SSLv3 servers. However, SSLv3 is now disabled by
default so this should be moot.
It would be possible to avoid much of this change and just support
SHA-384 for the ServerKeyExchange as the SKX only signs over the nonces
and SKX params (a design mistake in TLS). However, that would leave Go
in the odd situation where it advertised support for SHA-384, but would
only use the handshake hash when signing client certificates. I fear
that'll just cause problems in the future.
Much of this code was written by davidben@ for the purposes of testing
BoringSSL.
Partly addresses #9757
Change-Id: I5137a472b6076812af387a5a69fc62c7373cd485
Reviewed-on: https://go-review.googlesource.com/9415
Run-TryBot: Adam Langley <agl@golang.org>
Reviewed-by: Adam Langley <agl@golang.org>
This change adds support for serving and receiving Signed Certificate
Timestamps as described in RFC 6962.
The server is now capable of serving SCTs listed in the Certificate
structure. The client now asks for SCTs and, if any are received,
they are exposed in the ConnectionState structure.
Fixes#10201
Change-Id: Ib3adae98cb4f173bc85cec04d2bdd3aa0fec70bb
Reviewed-on: https://go-review.googlesource.com/8988
Reviewed-by: Adam Langley <agl@golang.org>
Run-TryBot: Adam Langley <agl@golang.org>
Reviewed-by: Jonathan Rudenberg <jonathan@titanous.com>
Generalizes PRF calculation for TLS 1.2 to support arbitrary hashes (SHA-384 instead of SHA-256).
Testdata were all updated to correspond with the new cipher suites in the handshake.
Change-Id: I3d9fc48c19d1043899e38255a53c80dc952ee08f
Reviewed-on: https://go-review.googlesource.com/3265
Reviewed-by: Adam Langley <agl@golang.org>
Signer is an interface to support opaque private keys.
These keys typically result from being kept in special hardware
(i.e. a TPM) although sometimes operating systems provide a
similar interface using process isolation for security rather
than hardware boundaries.
This changes provides interfaces for representing them and
alters crypto/tls so that client certificates can use
opaque keys.
LGTM=bradfitz
R=bradfitz
CC=golang-codereviews, jdeprez
https://golang.org/cl/114680043
Currently a write error will cause future reads to return that same error.
However, there may have been extra information from a peer pending on
the read direction that is now unavailable.
This change splits the single connErr into errors for the read, write and
handshake. (Splitting off the handshake error is needed because both read
and write paths check the handshake error.)
Fixes#7414.
LGTM=bradfitz, r
R=golang-codereviews, r, bradfitz
CC=golang-codereviews
https://golang.org/cl/69090044
Currently an ECDHE handshake uses the client's curve preference. This
generally means that we use P-521. However, P-521's strength is
mismatched with the rest of the cipher suite in most cases and we have
a fast, constant-time implementation of P-256.
With this change, Go servers will use P-256 where the client supports
it although that can be overridden in the Config.
LGTM=bradfitz
R=bradfitz
CC=golang-codereviews
https://golang.org/cl/66060043
crypto/tls has two functions for creating a client connection: Dial,
which most users are expected to use, and Client, which is the
lower-level API.
Dial does what you expect: it gives you a secure connection to the host
that you specify and the majority of users of crypto/tls appear to work
fine with it.
Client gives more control but needs more care. Specifically, if it
wasn't given a server name in the tls.Config then it didn't check that
the server's certificates match any hostname - because it doesn't have
one to check against. It was assumed that users of the low-level API
call VerifyHostname on the certificate themselves if they didn't supply
a hostname.
A review of the uses of Client both within Google and in a couple of
external libraries has shown that nearly all of them got this wrong.
Thus, this change enforces that either a ServerName or
InsecureSkipVerify is given. This does not affect tls.Dial.
See discussion at https://groups.google.com/d/msg/golang-nuts/4vnt7NdLvVU/b1SJ4u0ikb0J.
Fixes#7342.
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/67010043
Adam (agl@) had already done an initial review of this CL in a branch.
Added ClientSessionState to Config which now allows clients to keep state
required to resume a TLS session with a server. A client handshake will try
and use the SessionTicket/MasterSecret in this cached state if the server
acknowledged resumption.
We also added support to cache ClientSessionState object in Config that will
be looked up by server remote address during the handshake.
R=golang-codereviews, agl, rsc, agl, agl, bradfitz, mikioh.mikioh
CC=golang-codereviews
https://golang.org/cl/15680043
The renegotiation extension was introduced[1] due to an attack by Ray in
which a client's handshake was spliced into a connection that was
renegotiating, thus giving an attacker the ability to inject an
arbitary prefix into the connection.
Go has never supported renegotiation as a server and so this attack
doesn't apply. As a client, it's possible that at some point in the
future the population of servers will be sufficiently updated that
it'll be possible to reject connections where the server hasn't
demonstrated that it has been updated to address this problem.
We're not at that point yet, but it's good for Go servers to support
the extension so that it might be possible to do in the future.
[1] https://tools.ietf.org/search/rfc5746
R=golang-codereviews, mikioh.mikioh
CC=golang-codereviews
https://golang.org/cl/48580043
Despite SHA256 support being required for TLS 1.2 handshakes, some
servers are aborting handshakes that don't offer SHA1 support.
This change adds support for signing TLS 1.2 ServerKeyExchange messages
with SHA1. It does not add support for signing TLS 1.2 client
certificates with SHA1 as that would require the handshake to be
buffered.
Fixes#6618.
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/15650043
AES-GCM cipher suites are only defined for TLS 1.2, although there's
nothing really version specific about them. However, development
versions of NSS (meaning Firefox and Chrome) have an issue where
they'll advertise TLS 1.2-only cipher suites in a TLS 1.1 ClientHello
but then balk when the server selects one.
This change causes Go clients not to advertise TLS 1.2 cipher suites
unless TLS 1.2 is being used, and prevents servers from selecting them
unless TLS 1.2 has been negotiated.
https://code.google.com/p/chromium/issues/detail?id=297151https://bugzilla.mozilla.org/show_bug.cgi?id=919677
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/13573047
With TLS 1.2, when sending client certificates the code was omitting
the new (in TLS 1.2) signature and hash fields.
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/13413050
AES-GCM is the only current TLS ciphersuite that doesn't have
cryptographic weaknesses (RC4), nor major construction issues (CBC mode
ciphers) and has some deployment (i.e. not-CCM).
R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/13249044
Add support for ECDHE-ECDSA (RFC4492), which uses an ephemeral server
key pair to perform ECDH with ECDSA signatures. Like ECDHE-RSA,
ECDHE-ECDSA also provides PFS.
R=agl
CC=golang-dev
https://golang.org/cl/7006047
This does not include AES-GCM yet. Also, it assumes that the handshake and
certificate signature hash are always SHA-256, which is true of the ciphersuites
that we currently support.
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/10762044
The significant change between TLS 1.0 and 1.1 is the addition of an explicit IV in the case of CBC encrypted records. Support for TLS 1.1 is needed in order to support TLS 1.2.
R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/7880043
Currently we only check the leaf node's issuer against the list of
distinguished names in the server's CertificateRequest message. This
will fail if the client certiciate has more than one certificate in
the path and the leaf node issuer isn't in the list of distinguished
names, but the issuer's issuer was in the distinguished names.
R=agl, agl
CC=gobot, golang-dev
https://golang.org/cl/9795043
