Spotted by Coverity. If PuTTY is functioning as a sharing upstream,
and a new downstream mishandles the version string exchange in any way
that provokes an error message from share_receive() (such as failing
to start the greeting with the expected protocol-name string), we were
calling share_disconnect() and then going to crFinish. But
share_disconnect is capable of actually freeing the entire
ssh_sharing_connstate which contains the coroutine state - in which
case, crFinish's zeroing out of crLine is a use-after-free.
The usual pattern elsewhere in this code is to exit a coroutine with
an ordinary 'return' when you've destroyed its state structure. Switch
to doing that here.
When you send a "publickey" USERAUTH_REQUEST containing a certified
RSA key, and you want to use a SHA-2 based RSA algorithm, modern
OpenSSH expects you to send the algorithm string as
rsa-sha2-NNN-cert-v01@openssh.com. But 7.7 and earlier didn't
recognise those names, and expected the algorithm string in the
userauth request packet to be ssh-rsa-cert-v01@... and would then
follow it with an rsa-sha2-NNN signature.
OpenSSH itself has a bug workaround for its own older versions. Follow
suit.
If you specify a detached certificate, it's supposed to completely
replace any certificate that might have been embedded in the input PPK
file. But one thing wasn't working: if the key was RSA, and the server
was using new SHA-2 based RSA, and the user provided both an embedded
_and_ detached certificate, then the initial call to
ssh2_userauth_signflags would upgrade the ssh-rsa-cert-... key type to
rsa-sha2-NNN-cert-..., which ssh2_userauth_add_alg_and_publickey's
call to ssh_keyalg_related_alg would not recognise as any of the base
RSA types while trying to decide on the key algorithm string _after_
replacing the certificate.
Fixed by reverting to the the uncertified base algorithm before
calling ssh_keyalg_related_alg.
Introduced in the previous commit. The new ssh_ppl_final_output method
shouldn't be called in any of the error cleanup functions if
ssh->base_layer is NULL, which it can be if we haven't got far enough
through the connection to set up any packet protocol layers at
all. (For example, ECONNREFUSED would do it.)
This should fix the bug mentioned three commits ago: if an SSH server
sends a userauth banner and then immediately slams the connection
shut (with or without SSH_MSG_DISCONNECT), the banner message should
now be reliably printed to the user, which is important if that's
where the server put its explanation for the disconnection (e.g. "Your
account has expired").
(cherry picked from commit e8becb45b5)
No functional change: I've just pulled out into separate subroutines
the piece of code that process a USERAUTH_BANNER message and append
it to our banner bufchain, and the piece that prints the contents of
the bufchain as user output. This will enable them to be called from
additional places easily.
(cherry picked from commit 99bbbd8d32)
This is called just before closing the connection, and gives every PPL
one last chance to output anything to the user that it might have
buffered.
No functional change: all implementations so far are trivial, except
that the transport layer passes the call on to its higher
layer (because otherwise nothing would do so).
(cherry picked from commit d6e6919f69)
For the same reason that diffie-hellman-group18 goes below group16:
it's useful to _have_ it there, in case a server demands it, but under
normal circumstances it seems like overkill and a waste of CPU.
SHA-256 is not only intrinsically faster, it's also more likely to be
hardware-accelerated, so PuTTY's preference is to use that if possible
and SHA-512 only if necessary.
(cherry picked from commit 289d123fb8)
I saw a post on comp.security.ssh just now where someone had
encountered an SSH server that would _only_ speak that, which makes it
worth bothering to implement.
The totally obvious implementation works, and passes the test cases
from RFC 6234.
(cherry picked from commit b77e985513)
ssh->base_layer is NULL when the connection is still in its early
stages, before greetings are exchanged. If the user invokes the Change
Settings dialog in this situation, ssh_reconfig would call
ssh_ppl_reconfigure() on ssh->base_layer without checking if it was
NULL first.
(cherry picked from commit d67c13eeb8)
While writing the previous patch, I realise that walking along a
decrypted string and stopping to complain about the first mismatch you
find is an anti-pattern. If we're going to deliberately give the same
error message for various mismatches, so as not to give away which
part failed first, then we should also avoid giving away the same
information via a timing leak!
I don't think this is serious enough to warrant the full-on advisory
protocol, because XDM-AUTHORIZATION-1 is rarely used these days and
also DES-based, so there are bigger problems with it. (Plus, why on
earth is it based on encryption anyway, not a MAC?) But since I
spotted it in passing, might as well fix it.
(cherry picked from commit 8e7e3c5944)
Now the return value is a dynamically allocated string instead of a
static one, which means that the error message can include details
taken from the specific failing connection. In particular, if someone
requests an X11 authorisation protocol we don't support, we can print
its name as part of the message, which may help users debug the
problem.
One particularly important special case of this is that if the client
connection presents _no_ authorisation - which is surely by far the
most likely thing to happen by accident, e.g. if the auth file has
gone missing, or the hostname doesn't match for some reason - then we
now give a specific message "No authorisation provided", which I think
is considerably more helpful than just lumping that very common case
in with "Unsupported authorisation protocol". Even changing the latter
to "Unsupported authorisation protocol ''" is still not very sensible.
The problem in that case is not that the user has tried an exotic auth
protocol we've never heard of - it's that they've forgotten, or
failed, to provide one at all.
The error message for "XDM-AUTHORIZATION-1 data was wrong length" is
the other modified one: it now says what the wrong length _was_.
However, all other failures of X-A-1 are still kept deliberately
vague, because saying which part of the decrypted string didn't match
is an obvious information leak.
(cherry picked from commit dff4bd4d14)
I thought I'd found all of these before, but perhaps a few managed to
slip in since I last looked. The character argument to the <ctype.h>
functions must have the value of an unsigned char or EOF; passing an
ordinary char (unless you know char is unsigned on every platform the
code will ever go near) risks mistaking '\xFF' for EOF, and causing
outright undefined behaviour on byte values in the range 80-FE. Never
do it.
(cherry picked from commit a76109c586)
Like 5f3b743eb0, specifically reassure the user that taking the
add-to-cache action will not cause the CA that signed the key to be
trusted in any wider context, in the case where there was no previous
certified key cached. (I don't know why I missed this out before.)
(cherry picked from commit 9209c7ea38)
Jacob spotted that an unused -pwfile input can be accidentally used as
the answer to Plink's antispoof 'press Return to begin session'
prompt, which is unintended and confusing.
To fix that, I've made the use of a command-line password conditional
on p->to_server, the flag in a prompts_t that indicates whether the
results of the prompts are going to be sent directly to the server or
consumed locally by PuTTY. (And I've also corrected the setting of
to_server in the antispoof prompt, which was true when it should have
been false.)
A side effect of this is that -pwfile will no longer work to provide a
private-key passphrase, if you're using public-key authentication
without Pageant. This is deliberate, because if you're doing that on
purpose then Pageant is a better way to achieve the same thing (or
else just store the key unencrypted, which is no worse); but in the
case of a server that sequentially demands public-key _and_ password
authentication, the new behaviour makes -pwfile apply to the right one
of the two prompts, i.e. the actual password.
This was pointed out by another compiler warning. The 'name' parameter
of inquire_cred_by_mech is not a gss_name_t (which is the type of
GSS_C_NO_NAME); it's a gss_name_t *, because it's an _output_
parameter. We're not telling the library that we aren't _passing_ a
name: we're telling it that we don't need it to _return_ us a name. So
the appropriate null pointer representation is just NULL.
(This was harmless apart from a compiler warning, because gss_name_t
is a pointer type in turn and GSS_C_NO_NAME expands to a null pointer
anyway. It was just a wrongly-typed null pointer.)
Heimdal provides its own definitions of OIDs like GSS_C_NT_USER_NAME
in the form of macros, which conflict with our attempt to redefine
them as variables - the macro gets expanded into the middle of the
variable declaration, leaving the poor C compiler trying to parse a
non-declaration along the lines of
const_gss_OID (&__gss_c_nt_anonymous_oid_desc) = oids+5;
Easily fixed by just not redefining these at all if they're already
defined as macros. To make that easier, I've broken up the oids[]
array into individual gss_OID_desc declarations, so I can put each one
inside the appropriate ifdef.
In the process, I've removed the 'const' from the gss_OID_desc
declarations. That's on purpose! The problem is that not all
implementations of the GSSAPI headers make const_gss_OID a pointer to
a *const* gss_OID_desc; sometimes it's just a plain one and the
'const' prefix is just a comment to the user. So removing that const
prevents compiler warnings (or worse) about address-taking a const
thing and assigning it into a non-const pointer.
dh_is_gex() expects to find a 'struct dh_extra' in the 'extra' field
of the kex_alg you pass in, and won't look kindly on finding an
instance of some totally different structure type. We were being
careful about that everywhere in the GSSAPI kex code except for the
final free step.
Just spotted this in eyeball review: we're about to construct our new
outgoing KEXINIT and write it into the strbuf s->outgoing_kexinit. So
we should clear that strbuf first. But in fact we were clearing
s->client_kexinit, which aliases s->outgoing_kexinit in an SSH client,
but in a server, aliases s->incoming_kexinit.
This was harmless in PuTTY (since the strbuf we cleared was the right
one anyway). And it was harmless in Uppity's initial kex (since the
strbuf we _meant_ to clear was empty anyway). But if Uppity had ever
initiated a rekey, this would have exploded messily.
I only realised this bug while writing up the feature for the
wishlist:
It's one thing _at connection startup_ to delay sending your KEXINIT
until the server has sent its: the server is very likely to send it
anyway (unless it's attempting the same workaround against us), so
probably nothing goes wrong.
But if we want to initiate a rekey, we do that _by_ sending a KEXINIT.
In that situation we can't just wait until the server sends one,
because it has no idea it's supposed to be doing so!
Happily, in that situation, we already have a KEXINIT from the server,
left over from the previous key exchange. So we can filter against
that, and still have the intended effect of not spending KEXINIT space
on algorithms the server doesn't know about.
My correspondent on the new authentication-plugin feature reports that
their plugin is not reliably receiving the final PLUGIN_AUTH_SUCCESS
message on Windows. I _think_ this is because the whole userauth layer
is being dismissed, leading to sk_close() of the Socket talking to the
plugin, before the data has actually been written to the outgoing
pipe.
This should fix it: track the Socket's backlog, and immediately after
sending that message, wait until we receive a notification that the
backlog has decreased to size 0. That stops us from terminating the
userauth layer until the message has left our process.
In recent months I've had two requests from different people to build
support into PuTTY for automatically handling complicated third-party
auth protocols layered on top of keyboard-interactive - the kind of
thing where you're asked to enter some auth response, and you have to
refer to some external source like a web server to find out what the
right response _is_, which is a pain to do by hand, so you'd prefer it
to be automated in the SSH client.
That seems like a reasonable thing for an end user to want, but I
didn't think it was a good idea to build support for specific
protocols of that kind directly into PuTTY, where there would no doubt
be an ever-lengthening list, and maintenance needed on all of them.
So instead, in collaboration with one of my correspondents, I've
designed and implemented a protocol to be spoken between PuTTY and a
plugin running as a subprocess. The plugin can opt to handle the
keyboard-interactive authentication loop on behalf of the user, in
which case PuTTY passes on all the INFO_REQUEST packets to it, and
lets it make up responses. It can also ask questions of the user if
necessary.
The protocol spec is provided in a documentation appendix. The entire
configuration for the end user consists of providing a full command
line to use as the subprocess.
In the contrib directory I've provided an example plugin written in
Python. It gives a set of fixed responses suitable for getting through
Uppity's made-up k-i system, because that was a reasonable thing I
already had lying around to test against. But it also provides example
code that someone else could pick up and insert their own live
response-provider into the middle of, assuming they were happy with it
being in Python.
No functional change, but I've pulled the bulk of the k-i setup and
prompting code out of ssh2_userauth_process_queue and into
subroutines, in preparation for wanting to do the same work in more
than one place in the main coroutine's control flow.
I'm going to want to use it in an upcoming commit, because together
with 'savedhost', it forms the identification of an SSH server (at
least as far as the host key cache is concerned, and therefore it's
appropriate for other uses too).
We were already passing the hostname through for use in user-facing
prompts (not to mention the FQDN version for use in GSSAPI).
We've occasionally had reports of SSH servers disconnecting as soon as
they receive PuTTY's KEXINIT. I think all such reports have involved
the kind of simple ROM-based SSH server software you find in small
embedded devices.
I've never been able to prove it, but I've always suspected that one
possible cause of this is simply that PuTTY's KEXINIT is _too long_,
either in number of algorithms listed or in total length (especially
given all the ones that end in @very.long.domain.name suffixes).
If I'm right about either of those being the cause, then it's just
become even more likely to happen, because of all the extra
Diffie-Hellman groups and GSSAPI algorithms we just threw into our
already-long list in the previous few commits.
A workaround I've had in mind for ages is to wait for the server's
KEXINIT, and then filter our own down to just the algorithms the
server also mentioned. Then our KEXINIT is no longer than that of the
server, and hence, presumably fits in whatever buffer it has. So I've
implemented that workaround, in anticipation of it being needed in the
near future.
(Well ... it's not _quite_ true that our KEXINIT is at most the same
length as the server. In fact I had to leave in one KEXINIT item that
won't match anything in the server's list, namely "ext-info-c" which
gates access to SHA-2 based RSA. So if we turn out to support
absolutely everything on all the server's lists, then our KEXINIT
would be a few bytes longer than the server's, even with this
workaround. But that would only cause trouble if the server's outgoing
KEXINIT was skating very close to whatever buffer size it has for the
incoming one, and I'm guessing that's not very likely.)
((Another possible cause of this kind of disconnection would be a
server that simply objects to seeing any KEXINIT string it doesn't
know how to speak. But _surely_ no such server would have survived
initial testing against any full-featured client at all!))
This is surprisingly simple, because it wasn't necessary to touch the
GSS parts at all. Nothing changes about the message formats between
integer DH and ECDH in GSS KEX, except that the mpints sent back and
forth as part of integer DH are replaced by the opaque strings used in
ECDH. So I've invented a new KEXTYPE and made it control a bunch of
small conditionals in the middle of the GSS KEX code, leaving the rest
unchanged.
None of the constructors can fail and return NULL. I think this must
have come in with a lot of other unnecessary null-pointer checks when
ECC support was first added. I've got rid of most of them since then,
but that one apparently escaped my notice.
Introduced recently by commit 42740a5455, in which I decided to
call ssh_key_cache_str() even on certified host keys. But that call
was conditional on s->hkey being non-NULL (which happens in GSS KEX)
as well as on it not being certified, and I managed to absentmindedly
remove _both_ conditions. As a result we got a null-pointer
dereference on any GSS kex.
I ran 'ls /usr/share/doc' in a psusan session the other day and the
output hung part way through the long directory listing. This turned
out to be because the ssh-connection channel window had run out
temporarily, and PuTTY had sent a WINDOW_ADJUST extending it again,
which the connection layer acted on by calling chan_set_input_wanted
... which sesschan was ignoring with a comment saying /* I don't think
we need to do anything here */.
Well, turns out we do need to. Implemented the simplest possible
unblocking action.
I only recently found out that OpenSSH defined their own protocol IDs
for AES-GCM, defined to work the same as the standard ones except that
they fixed the semantics for how you select the linked cipher+MAC pair
during key exchange.
(RFC 5647 defines protocol ids for AES-GCM in both the cipher and MAC
namespaces, and requires that you MUST select both or neither - but
this contradicts the selection policy set out in the base SSH RFCs,
and there's no discussion of how you resolve a conflict between them!
OpenSSH's answer is to do it the same way ChaCha20-Poly1305 works,
because that will ensure the two suites don't fight.)
People do occasionally ask us for this linked cipher/MAC pair, and now
I know it's actually feasible, I've implemented it, including a pair
of vector implementations for x86 and Arm using their respective
architecture extensions for multiplying polynomials over GF(2).
Unlike ChaCha20-Poly1305, I've kept the cipher and MAC implementations
in separate objects, with an arm's-length link between them that the
MAC uses when it needs to encrypt single cipher blocks to use as the
inputs to the MAC algorithm. That enables the cipher and the MAC to be
independently selected from their hardware-accelerated versions, just
in case someone runs on a system that has polynomial multiplication
instructions but not AES acceleration, or vice versa.
There's a fourth implementation of the GCM MAC, which is a pure
software implementation of the same algorithm used in the vectorised
versions. It's too slow to use live, but I've kept it in the code for
future testing needs, and because it's a convenient place to dump my
design comments.
The vectorised implementations are fairly crude as far as optimisation
goes. I'm sure serious x86 _or_ Arm optimisation engineers would look
at them and laugh. But GCM is a fast MAC compared to HMAC-SHA-256
(indeed compared to HMAC-anything-at-all), so it should at least be
good enough to use. And we've got a working version with some tests
now, so if someone else wants to improve them, they can.
This provides a convenient hook to be called between SSH messages, for
the crypto components to do any per-message processing like
incrementing a sequence number.
In the situation where a MAC and cipher implementation are tied
together by being facets of the same underlying object (used by the
inseparable ChaCha20 + Poly1305 pair), previously we freed them by
having the cipher_free function actually do the freeing, having the
mac_free function do nothing, and taking great care to call those in
the right order. (Otherwise, the mac_free function dereferences a
no-longer-valid vtable pointer and doesn't get as far as _finding out_
that it doesn't have to do anything.)
That's a time bomb in general, and especially awkward in situations
like testcrypt where we don't get precise control over freeing order
in any case. So I've replaced that system with one in which there are
two flags in the ChaCha20-Poly1305 structure, saying whether each of
the cipher and MAC facets is currently considered to be allocated.
When the last of those flags is cleared, the object is actually freed.
So now they can be freed in either order.
OpenSSH, when called on to give the fingerprint of a certified public
key, will in many circumstances generate the hash of the public blob
of the _underlying_ key, rather than the hash of the full certificate.
I think the hash of the certificate is also potentially useful (if
nothing else, it provides a way to tell apart multiple certificates on
the same key). But I can also see that it's useful to be able to
recognise a key as the same one 'really' (since all certificates on
the same key share a private key, so they're unavoidably related).
So I've dealt with this by introducing an extra pair of fingerprint
types, giving the cross product of {MD5, SHA-256} x {base key only,
full certificate}. You can manually select which one you want to see
in some circumstances (notably PuTTYgen), and in others (such as
diagnostics) both fingerprints will be emitted side by side via the
new functions ssh2_double_fingerprint[_blob].
The default, following OpenSSH, is to just fingerprint the base key.
This patch fixes a few other whitespace and formatting issues which
were pointed out by the bulk-reindent or which I spotted in passing,
some involving manual editing to break lines more nicely.
I think the weirdest hunk in here is the one in windows/window.c
TranslateKey() where _half_ of an assignment statement inside an 'if'
was on the same line as the trailing paren of the if condition. No
idea at all how that one managed to happen!
I think a lot of these were inserted by a prior run through GNU indent
many years ago. I noticed in a more recent experiment that that tool
doesn't always correctly distinguish which instances of 'id * id' are
pointer variable declarations and which are multiplications, so it
spaces some of the former as if they were the latter.
If the function name (or expression) in a function call or declaration
is itself so long that even the first argument doesn't fit after it on
the same line, or if that would leave so little space that it would be
silly to try to wrap all the run-on lines into a tall thin column,
then I used to do this
ludicrously_long_function_name
(arg1, arg2, arg3);
and now prefer this
ludicrously_long_function_name(
arg1, arg2, arg3);
I picked up the habit from Python, where the latter idiom is required
by Python's syntactic significance of newlines (you can write the
former if you use a backslash-continuation, but pretty much everyone
seems to agree that that's much uglier). But I've found it works well
in C as well: it makes it more obvious that the previous line is
incomplete, it gives you a tiny bit more space to wrap the following
lines into (the old idiom indents the _third_ line one space beyond
the second), and I generally turn out to agree with the knock-on
indentation decisions made by at least Emacs if you do it in the
middle of a complex expression. Plus, of course, using the _same_
idiom between C and Python means less state-switching.
So, while I'm making annoying indentation changes in general, this
seems like a good time to dig out all the cases of the old idiom in
this code, and switch them over to the new.
My bulk indentation check also turned up a lot of cases where a run-on
function call or if statement didn't have its later lines aligned
correctly relative to the open paren.
I think this is quite easy to do by getting things out of
sync (editing the first line of the function call and forgetting to
update the rest, perhaps even because you never _saw_ the rest during
a search-replace). But a few didn't quite fit into that pattern, in
particular an outright misleading case in unix/askpass.c where the
second line of a call was aligned neatly below the _wrong_ one of the
open parens on the opening line.
Restored as many alignments as I could easily find.
In several pieces of development recently I've run across the
occasional code block in the middle of a function which suddenly
switched to 2-space indent from this code base's usual 4. I decided I
was tired of it, so I ran the whole code base through a re-indenter,
which made a huge mess, and then manually sifted out the changes that
actually made sense from that pass.
Indeed, this caught quite a few large sections with 2-space indent
level, a couple with 8, and a handful of even weirder things like 3
spaces or 12. This commit fixes them all.
In the case where a server presents a host key signed by a different
certificate from the one you've configured, it need not _always_ be
evidence of wrongdoing. I can imagine situations in which two CAs
cover overlapping sets of things, and you don't want to blanket-trust
one of them, but you do want to connect to a specific host signed by
that one.
Accordingly, PuTTY's previous policy of unconditionally aborting the
connection if certificate validation fails (which was always intended
as a stopgap until I thought through what I wanted to replace it with)
is now replaced by fallback handling: we present the host key
fingerprint to the user and give them the option to accept and/or
cache it based on the public key itself.
This means that the certified key types have to have a representation
in the host key cache. So I've assigned each one a type id, and
generate the cache string itself by simply falling back to the base
key.
(Rationale for the latter: re-signing a public key with a different
certificate doesn't change the _private_ key, or the set of valid
signatures generated with it. So if you've been convinced for reasons
other than the certificate that a particular private key is in the
possession of $host, then proof of ownership of that private key
should be enough to convince you you're talking to $host no matter
what CA has signed the public half this week.)
We now offer to receive a given certified host key type if _either_ we
have at least one CA configured to trust that host, _or_ we have a
certified key of that type cached. (So once you've decided manually
that you trust a particular key, we can still receive that key and
authenticate the host with it, even if you later delete the CA record
that it didn't match anyway.)
One change from normal (uncertified) host key handling is that for
certified key types _all_ the host key prompts use the stronger
language, with "WARNING - POTENTIAL SECURITY BREACH!" rather than the
mild 'hmm, we haven't seen this host before'. Rationale: if you
expected this CA key and got that one, it _could_ be a bold-as-brass
MITM attempt in which someone hoped you'd accept their entire CA key.
The mild wording is only for the case where we had no previous
expectations _at all_ for the host to violate: not a CA _or_ a cached
key.
In the macro automation for ssh2_bpp_check_unimplemented, I #defined
SSH2_BITMAP_WORD, and 20 lines later, tried to #undef it by the wrong
spelling. Of course this gave no error, so I didn't notice! But I
spotted it just now, so let's fix it.
The text of the host key warnings was replicated in three places: the
Windows rc file, the GTK dialog setup function, and the console.c
shared between both platforms' CLI tools. Now it lives in just one
place, namely ssh/common.c where the rest of the centralised host-key
checking is done, so it'll be easier to adjust the wording in future.
This comes with some extra automation. Paragraph wrapping is no longer
done by hand in any version of these prompts. (Previously we let GTK
do the wrapping on GTK, but on Windows the resource file contained a
bunch of pre-wrapped LTEXT lines, and console.c had pre-wrapped
terminal messages.) And the dialog heights in Windows are determined
automatically based on the amount of stuff in the window.
The main idea of all this is that it'll be easier to set up more
elaborate kinds of host key prompt that deal with certificates (if,
e.g., a server sends us a certified host key which we don't trust the
CA for). But there are side benefits of this refactoring too: each
tool now reliably inserts its own appname in the prompts, and also, on
Windows the entire prompt text is copy-pastable.
Details of implementation: there's a new type SeatDialogText which
holds a set of (type, string) pairs describing the contents of a
prompt. Type codes distinguish ordinary text paragraphs, paragraphs to
be displayed prominently (like key fingerprints), the extra-bold scary
title at the top of the 'host key changed' version of the dialog, and
the various information that lives in the subsidiary 'more info' box.
ssh/common.c constructs this, and passes it to the Seat to present the
actual prompt.
In order to deal with the different UI for answering the prompt, I've
added an extra Seat method 'prompt_descriptions' which returns some
snippets of text to interpolate into the messages. ssh/common.c calls
that while it's still constructing the text, and incorporates the
resulting snippets into the SeatDialogText.
For the moment, this refactoring only affects the host key prompts.
The warnings about outmoded crypto are still done the old-fashioned
way; they probably ought to be similarly refactored to use this new
SeatDialogText system, but it's not immediately critical for the
purpose I have right now.
This replaces the previous placeholder scheme of having a list of
hostname wildcards with implicit logical-OR semantics (if any wildcard
matched then the certificate would be trusted to sign for that host).
That scheme didn't allow for exceptions within a domain ('everything
in example.com except extra-high-security-machine.example.com'), and
also had no way to specify port numbers.
In the new system, you can still write a hostname wildcard by itself
in the simple case, but now those are just atomic subexpressions in a
boolean-logic domain-specific language I've made up. So if you want
multiple wildcards, you can separate them with || in a single longer
expression, and also you can use && and ! to impose exceptions on top
of that.
Full details of the expression language are in the comment at the top
of utils/cert-expr.c. It'll need documenting properly before release,
of course.
For the sake of backwards compatibility for early adopters who've
already set up configuration in the old system, I've put in some code
that will read the old MatchHosts configuration and automatically
translate it into the equivalent boolean expression (by simply
stringing together the list of wildcards with || between them).
Now we check that we can actually make an ssh_key out of it, and
moreover, that the key is of a sensible kind (i.e. not a certificate
in turn). If that's not true, we report something about the problem in
a new CTRL_TEXT below the public key input box. If the key _is_ valid,
that same text control is used to show its type, length and
fingerprint.
On Windows, I've widened the dialog box a little to make fingerprints
fit sensibly in it.
Now the RSA signature-type checkboxes should be aligned with their
label; the 'Add' and 'Remove' buttons for wildcards should align with
the edit box for entering a wildcard; and the 'Load from file' button
for a public key aligns with the edit box for that.
