This reuses all the named-pipe IPC code I set up for connection
sharing a few years ago, to set up a named pipe with a predictable
name and speak the stream-oriented SSH agent protocol over it.
In this commit, we just set up the server, and there's no code that
speaks the client end of the new IPC yet. But my plan is that clients
should switch over to using this interface if possible, because it's
generally better: it doesn't have to be handled synchronously in the
middle of a GUI event loop (either in Pageant itself _or_ in its
client), and it's a better fit to the connection-oriented nature of
forwarded agent connections (so if any features ever appear in the
agent protocol that require state within a connection, we'll now be
able to support them).
This contains most of the guts of the previously monolithic function
new_named_pipe_client(), but it directly returns the HANDLE to the
opened pipe, or a string error message on failure.
new_named_pipe_client() is now a thin veneer on top of that, which
returns a Socket * by wrapping up the HANDLE into a HandleSocket or
the error message into an ErrorSocket as appropriate.
So it's now possible to connect to a named pipe, using all our usual
infrastructure (including in particular the ownership check of the
server, to defend against spoofing attacks), without having to have a
Socket-capable event loop in progress.
Windows Plink and PSFTP had very similar implementations, and now they
share one that lives in a new file winselcli.c. I've similarly moved
GUI PuTTY's implementation out of window.c into winselgui.c, where
other GUI programs wanting to do networking will be able to access
that too.
In the spirit of centralisation, I've also taken the opportunity to
make both functions use the reasonably complete winsock_error_string()
rather than (for some historical reason) each inlining a minimal
version that reports most errors as 'unknown'.
The do_select function is called with a boolean parameter indicating
whether we're supposed to start or stop paying attention to network
activity on a given socket. So if we freeze and unfreeze the socket in
mid-session because of backlog, we'll call do_select(s, false) to
freeze it, and do_select(s, true) to unfreeze it.
But the implementation of do_select in the Windows SFTP code predated
the rigorous handling of socket backlogs, so it assumed that
do_select(s, true) would only be called at initialisation time, i.e.
only once, and therefore that it was safe to use that flag as a cue to
set up the Windows event object to associate with socket activity.
Hence, every time the socket was frozen and unfrozen, we would create
a new netevent at unfreeze time, leaking the old one.
I think perhaps part of the reason why that was hard to figure out was
that the boolean parameter was called 'startup' rather than 'enable'.
To make it less confusing the next time I read this code, I've also
renamed it, and while I was at it, adjusted another related comment.
The number of people has been steadily increasing who read our source
code with an editor that thinks tab stops are 4 spaces apart, as
opposed to the traditional tty-derived 8 that the PuTTY code expects.
So I've been wondering for ages about just fixing it, and switching to
a spaces-only policy throughout the code. And I recently found out
about 'git blame -w', which should make this change not too disruptive
for the purposes of source-control archaeology; so perhaps now is the
time.
While I'm at it, I've also taken the opportunity to remove all the
trailing spaces from source lines (on the basis that git dislikes
them, and is the only thing that seems to have a strong opinion one
way or the other).
Apologies to anyone downstream of this code who has complicated patch
sets to rebase past this change. I don't intend it to be needed again.
The executables were already ignoring it.
This is a minimal change; PUTTY.HLP can still be built, and there's
still all the context IDs lying around.
Buildscr changes are untested.
With this change, we stop expecting to find putty.chm alongside the
executable file. That was a security hazard comparable to DLL
hijacking, because of the risk that a malicious CHM file could be
dropped into the same directory as putty.exe (e.g. if someone ran
PuTTY from their browser's download dir)..
Instead, the standalone putty.exe (and other binaries needing help)
embed the proper CHM file within themselves, as a Windows resource,
and if called on to display the help then they write the file out to a
temporary location. This has the advantage that if you download and
run the standalone putty.exe then you actually _get_ help, which
previously didn't happen!
The versions of the binaries in the installer don't each contain a
copy of the help file; that would be extravagant. Instead, the
installer itself writes a registry entry pointing at the proper help
file, and the executables will look there.
Another effect of this commit is that I've withdrawn support for the
older .HLP format completely. It's now entirely outdated, and
supporting it through this security fix would have been a huge pain.
I haven't tried compiling with /DMINEFIELD in a while, and when I just
did, I found that the declarations in winstuff.h weren't actually
being included by memory.c where they're needed.
My trawl of all the vtable systems in the code spotted a couple of
other function-like macros in passing, which might as well be
rewritten as inline functions too for the same reasons.
Rather like isatty() on Unix, this tells you if a raw Windows HANDLE
points at a console or not. Useful to know if your standard output or
standard error is going to be shown to a user, or redirected to
something that will make automated use of it.
There's now a stdio_sink, whose write function calls fwrite on the
given FILE *; a bufchain_sink, whose write function appends to the
given bufchain; and on Windows there's a handle_sink whose write
function writes to the given 'struct handle'. (That is, not the raw
Windows HANDLE, but our event-loop-friendly wrapper on it.)
Not yet used for anything, but they're about to be.
This is a general cleanup which has been overdue for some time: lots
of length fields are now the machine word type rather than the (in
practice) fixed 'int'.
Now we pass an error code in a separate dedicated parameter, instead
of overloading the length parameter so that a negative value means an
error code. This enables length to become unsigned without causing
trouble.
After I moved parts of misc.c into utils.c, we started getting two
versions of smemclr in the Windows builds, because utils.c didn't know
to omit its one, having not included the main putty.h.
But it was deliberate that utils.c didn't include putty.h, because I
wanted it (along with the rest of testcrypt in particular) to be
portable to unusual platforms without having to port the whole of the
code base.
So I've moved into the ubiquitous defs.h just the one decision about
whether we're on a platform that will supersede utils.c's definition
of smemclr.
(Also, in the process of moving it, I've removed the clause that
disabled the Windows smemclr in winelib mode, because it looks as if
the claim that winelib doesn't have SecureZeroMemory is now out of
date.)
Now they live in their own file memory.c. The advantage of this is
that you can link them into a binary without also pulling in the rest
of misc.c with its various dependencies on other parts of the code,
such as conf.c.
This is another cleanup I felt a need for while I was doing
boolification. If you define a function or variable in one .c file and
declare it extern in another, then nothing will check you haven't got
the types of the two declarations mismatched - so when you're
_changing_ the type, it's a pain to make sure you've caught all the
copies of it.
It's better to put all those extern declarations in header files, so
that the declaration in the header is also in scope for the
definition. Then the compiler will complain if they don't match, which
is what I want.
For a start, they now have different names on Windows and Unix,
reflecting their different roles: on Windows they apply escaping to
any string that's going to be used as a registry key (be it a session
name, or a host name for host key storage), whereas on Unix they're
for constructing saved-session file names in particular (and also
handle the special case of filling in "Default Settings" for NULL).
Also, they now produce output by writing to a strbuf, which simplifies
a lot of the call sites. In particular, the strbuf output idiom is
passed on to enum_settings_next, which is especially nice because its
only actual caller was doing an ad-hoc realloc loop that I can now get
rid of completely.
Thirdly, on Windows they're centralised into winmisc.c instead of
living in winstore.c, because that way Pageant can use the unescape
function too. (It was spotting the duplication there that made me
think of doing this in the first place, but once I'd started, I had to
keep unravelling the thread...)
Jumped out at me in my trawl of the whole code base:
set_explicit_app_user_model_id is declared and defined as () rather
than (void), but this isn't C++.
My normal habit these days, in new code, is to treat int and bool as
_almost_ completely separate types. I'm still willing to use C's
implicit test for zero on an integer (e.g. 'if (!blob.len)' is fine,
no need to spell it out as blob.len != 0), but generally, if a
variable is going to be conceptually a boolean, I like to declare it
bool and assign to it using 'true' or 'false' rather than 0 or 1.
PuTTY is an exception, because it predates the C99 bool, and I've
stuck to its existing coding style even when adding new code to it.
But it's been annoying me more and more, so now that I've decided C99
bool is an acceptable thing to require from our toolchain in the first
place, here's a quite thorough trawl through the source doing
'boolification'. Many variables and function parameters are now typed
as bool rather than int; many assignments of 0 or 1 to those variables
are now spelled 'true' or 'false'.
I managed this thorough conversion with the help of a custom clang
plugin that I wrote to trawl the AST and apply heuristics to point out
where things might want changing. So I've even managed to do a decent
job on parts of the code I haven't looked at in years!
To make the plugin's work easier, I pushed platform front ends
generally in the direction of using standard 'bool' in preference to
platform-specific boolean types like Windows BOOL or GTK's gboolean;
I've left the platform booleans in places they _have_ to be for the
platform APIs to work right, but variables only used by my own code
have been converted wherever I found them.
In a few places there are int values that look very like booleans in
_most_ of the places they're used, but have a rarely-used third value,
or a distinction between different nonzero values that most users
don't care about. In these cases, I've _removed_ uses of 'true' and
'false' for the return values, to emphasise that there's something
more subtle going on than a simple boolean answer:
- the 'multisel' field in dialog.h's list box structure, for which
the GTK front end in particular recognises a difference between 1
and 2 but nearly everything else treats as boolean
- the 'urgent' parameter to plug_receive, where 1 vs 2 tells you
something about the specific location of the urgent pointer, but
most clients only care about 0 vs 'something nonzero'
- the return value of wc_match, where -1 indicates a syntax error in
the wildcard.
- the return values from SSH-1 RSA-key loading functions, which use
-1 for 'wrong passphrase' and 0 for all other failures (so any
caller which already knows it's not loading an _encrypted private_
key can treat them as boolean)
- term->esc_query, and the 'query' parameter in toggle_mode in
terminal.c, which _usually_ hold 0 for ESC[123h or 1 for ESC[?123h,
but can also hold -1 for some other intervening character that we
don't support.
In a few places there's an integer that I haven't turned into a bool
even though it really _can_ only take values 0 or 1 (and, as above,
tried to make the call sites consistent in not calling those values
true and false), on the grounds that I thought it would make it more
confusing to imply that the 0 value was in some sense 'negative' or
bad and the 1 positive or good:
- the return value of plug_accepting uses the POSIXish convention of
0=success and nonzero=error; I think if I made it bool then I'd
also want to reverse its sense, and that's a job for a separate
piece of work.
- the 'screen' parameter to lineptr() in terminal.c, where 0 and 1
represent the default and alternate screens. There's no obvious
reason why one of those should be considered 'true' or 'positive'
or 'success' - they're just indices - so I've left it as int.
ssh_scp_recv had particularly confusing semantics for its previous int
return value: its call sites used '<= 0' to check for error, but it
never actually returned a negative number, just 0 or 1. Now the
function and its call sites agree that it's a bool.
In a couple of places I've renamed variables called 'ret', because I
don't like that name any more - it's unclear whether it means the
return value (in preparation) for the _containing_ function or the
return value received from a subroutine call, and occasionally I've
accidentally used the same variable for both and introduced a bug. So
where one of those got in my way, I've renamed it to 'toret' or 'retd'
(the latter short for 'returned') in line with my usual modern
practice, but I haven't done a thorough job of finding all of them.
Finally, one amusing side effect of doing this is that I've had to
separate quite a few chained assignments. It used to be perfectly fine
to write 'a = b = c = TRUE' when a,b,c were int and TRUE was just a
the 'true' defined by stdbool.h, that idiom provokes a warning from
gcc: 'suggest parentheses around assignment used as truth value'!
This commit includes <stdbool.h> from defs.h and deletes my
traditional definitions of TRUE and FALSE, but other than that, it's a
100% mechanical search-and-replace transforming all uses of TRUE and
FALSE into the C99-standardised lowercase spellings.
No actual types are changed in this commit; that will come next. This
is just getting the noise out of the way, so that subsequent commits
can have a higher proportion of signal.
After the recent Seat and LogContext revamps, _nearly_ all the
remaining uses of the type 'Frontend' were in terminal.c, which needs
all sorts of interactions with the GUI window the terminal lives in,
from the obvious (actually drawing text on the window, reading and
writing the clipboard) to the obscure (minimising, maximising and
moving the window in response to particular escape sequences).
All of those functions are now provided by an abstraction called
TermWin. The few remaining uses of Frontend after _that_ are internal
to a particular platform directory, so as to spread the implementation
of that particular kind of Frontend between multiple source files; so
I've renamed all of those so that they take a more specifically named
type that refers to the particular implementation rather than the
general abstraction.
So now the name 'Frontend' no longer exists in the code base at all,
and everywhere one used to be used, it's completely clear whether it
was operating in one of Frontend's three abstract roles (and if so,
which), or whether it was specific to a particular implementation.
Another type that's disappeared is 'Context', which used to be a
typedef defined to something different on each platform, describing
whatever short-lived resources were necessary to draw on the terminal
window: the front end would provide a ready-made one when calling
term_paint, and the terminal could request one with get_ctx/free_ctx
if it wanted to do proactive window updates. Now that drawing context
lives inside the TermWin itself, because there was never any need to
have two of those contexts live at the same time.
(Another minor API change is that the window-title functions - both
reading and writing - have had a missing 'const' added to their char *
parameters / return values.)
I don't expect this change to enable any particularly interesting new
functionality (in particular, I have no plans that need more than one
implementation of TermWin in the same application). But it completes
the tidying-up that began with the Seat and LogContext rework.
This is a new vtable-based abstraction which is passed to a backend in
place of Frontend, and it implements only the subset of the Frontend
functions needed by a backend. (Many other Frontend functions still
exist, notably the wide range of things called by terminal.c providing
platform-independent operations on the GUI terminal window.)
The purpose of making it a vtable is that this opens up the
possibility of creating a backend as an internal implementation detail
of some other activity, by providing just that one backend with a
custom Seat that implements the methods differently.
For example, this refactoring should make it feasible to directly
implement an SSH proxy type, aka the 'jump host' feature supported by
OpenSSH, aka 'open a secondary SSH session in MAINCHAN_DIRECT_TCP
mode, and then expose the main channel of that as the Socket for the
primary connection'. (Which of course you can already do by spawning
'plink -nc' as a separate proxy process, but this would permit it in
the _same_ process without anything getting confused.)
I've centralised a full set of stub methods in misc.c for the new
abstraction, which allows me to get rid of several annoying stubs in
the previous code. Also, while I'm here, I've moved a lot of
duplicated modalfatalbox() type functions from application main
program files into wincons.c / uxcons.c, which I think saves
duplication overall. (A minor visible effect is that the prefixes on
those console-based fatal error messages will now be more consistent
between applications.)
This is another major source of unexplained 'void *' parameters
throughout the code.
In particular, the currently unused testback.c actually gave the wrong
pointer type to its internal store of the frontend handle - it cast
the input void * to a Terminal *, from which it got implicitly cast
back again when calling from_backend, and nobody noticed. Now it uses
the right type internally as well as externally.
Nearly every part of the code that ever handles a full backend
structure has historically done it using a pair of pointer variables,
one pointing at a constant struct full of function pointers, and the
other pointing to a 'void *' state object that's passed to each of
those.
While I'm modernising the rest of the code, this seems like a good
time to turn that into the same more or less type-safe and less
cumbersome system as I'm using for other parts of the code, such as
Socket, Plug, BinaryPacketProtocol and so forth: the Backend structure
contains a vtable pointer, and a system of macro wrappers handles
dispatching through that vtable.
Same principle again - the more of these structures have globally
visible tags (even if the structure contents are still opaque in most
places), the fewer of them I can mistake for each other.
Rather than squelching the warning, I'm actually paying attention to
the deprecation, in that I'm allowing for the possibility that the
function might stop existing or stop returning success.
Apparently Windows on Arm has an emulator that lets it run x86
binaries without it being obvious, which could get confusing when
people start reporting what version of what they're running where.
(Indeed, it might get confusing for _me_ during early testing.) So now
the Windows builds explicitly state 'x86' or 'Arm' as well as 32- or
64-bit.
This centralises a few things that multiple header files were
previously defining, and were protecting against each other's
redefinition with ifdefs - small things like structs and typedefs. Now
all those things are in a defs.h which is by definition safe to
include _first_ (out of all the codebase-local headers) and only need
to be defined once.
On all platforms, you can now configure which clipboard the mouse
pastes from, which clipboard Ctrl-Ins and Shift-Ins access, and which
Ctrl-Shift-C and Ctrl-Shift-V access. In each case, the options are:
- nothing at all
- a clipboard which is implicitly written by the act of mouse
selection (the PRIMARY selection on X, CLIP_LOCAL everywhere else)
- the standard clipboard written by explicit copy/paste UI actions
(CLIPBOARD on X, the unique system clipboard elsewhere).
Also, you can control whether selecting text with the mouse _also_
writes to the explicitly accessed clipboard.
The wording of the various messages changes between platforms, but the
basic UI shape is the same everywhere.
This lays some groundwork for making PuTTY's cut and paste handling
more flexible in the area of which clipboard(s) it reads and writes,
if more than one is available on the system.
I've introduced a system of list macros which define an enumeration of
integer clipboard ids, some defined centrally in putty.h (at present
just a CLIP_NULL which never has any text in it, because that seems
like the sort of thing that will come in useful for configuring a
given copy or paste UI action to be ignored) and some defined per
platform. All the front end functions that copy and paste take a
clipboard id, and the Terminal structure is now configured at startup
to tell it which clipboard id it should paste from on a mouse click,
and which it should copy from on a selection.
However, I haven't actually added _real_ support for multiple X11
clipboards, in that the Unix front end supports a single CLIP_SYSTEM
regardless of whether it's in OS X or GTK mode. So this is currently a
NFC refactoring which does nothing but prepare the way for real
changes to come.
It's actually a function specific to the Windows front end, and has
been all along - but I've only just noticed that no other front end
either uses it or defines it.
stdint.h is one of the set of standard C headers that has more to do
with the compiler than the library, and hence, clang provides its own
version of it, even when you're using it in clang-cl mode with Visual
Studio headers, and even when those headers are old enough not to have
a stdint.h of their own. So in clang builds, including stdint.h is
always the right way to get uintptr_t defined.
Patch due to Brian K. White; we now condition our own declaration of
DLL_DIRECTORY_COOKIE on whether the toolchain's headers had #defined
it already, rather than trying to guess the answer to that from
version-number macros.
(Apparently everything that defines DLL_DIRECTORY_COOKIE does it by
does seem to work in all my tests.)
This too is not in the list of known DLLs on Windows 10. I don't know
of any actual viable hijacking attack based on it, which according to
my reading of MSDN (specifically, a rather vague hint in
https://msdn.microsoft.com/library/ff919712) _may_ be because we
mention the common controls assembly in our application manifest; but
better safe than sorry.
Now the entire list of remaining DLLs that PuTTY links against at load
time is a subset of the Win10 known DLLs list, so that _should_ mean
that everything we load before we've deployed our own defence
(SetDefaultDllDirectories) is defended against for us by Windows
itself.
This gives me an extra safety-check against having mistyped one of the
function prototypes that we load at run time from DLLs: we verify that
the typedef we defined based on the prototype in our source code
matches the type of the real function as declared in the Windows
headers.
This was an idea I had while adding a pile of further functions using
this mechanism. It didn't catch any errors (either in the new
functions or in the existing collection), but that's no reason not to
keep it anyway now that I've thought of it!
In VS2015, this automated type-check works for most functions, but a
couple manage to break it. SetCurrentProcessExplicitAppUserModelID in
winjump.c can't be type-checked, because including <shobjidl.h> where
that function is declared would also bring in a load of other stuff
that conflicts with the painful manual COM declarations in winjump.c.
(That stuff could probably be removed now we're on an up-to-date
Visual Studio, on the other hand, but that's a separate chore.) And
gai_strerror, used in winnet.c, does _have_ an implementation in a
DLL, but the header files like to provide an inline version with a
different calling convention, which defeats this error-checking trick.
And in the older VS2003 that we still precautionarily build with,
several more type-checks have to be #ifdeffed out because the
functions they check against just aren't there at all.
gssapi32.dll from MIT Kerberos as well as from Heimdal both load
further DLLs from their installation directories.
[SGT: I polished the original patch a bit, in particular replacing
manual memory allocation with dup_mb_to_wc. This required a Recipe
change to link miscucs.c and winucs.c into more of the tools.]
Avoided referring to some functions and header files that aren't there
in the winelib world (_vsnprintf, _stricmp, SecureZeroMemory,
multimon.h), and worked around a really amazingly annoying issue in
which Winelib objects to you using the type 'fd_set' unless you
included winsock2.h before stdlib.h.
clang-cl generates warnings saying they're deprecated, in favour of
the same names but prefixed with an underscore. The warnings are
coming from the standard MS headers, and I'm already #defining those
names differently on Unix, so I'll honour them.
This change applies to every situation when GUI PuTTY knowingly spawns
another GUI PuTTY, to wit, the System menu options 'New Session',
'Duplicate Session' and the 'Saved Sessions' submenu.
(Literally speaking, what we actually pass through to the sub-PuTTY's
command line is not the "-restrict-acl" option itself, but a special
prefix "&R", which has the same meaning but which lives in the special
pre-argv-splitting command-line namespace like the magic options used
for Duplicate Session and the old '@sessionname' prefix which the
Saved Sessions submenu still uses. Otherwise, by the time we split up
argv and recognised -restrict-acl, it would be too late to parse those
other options.)
One case in which PuTTY spawns a subprocess and this change _doesn't_
apply is when the subprocess is a proxy command which happens to be a
Plink. Recognising Plink commands in that situation would be fragile
and unreliable, and in any case if the user wants a proxy Plink to be
ACL-restricted, they are in control of its exact command line so they
can add -restrict-acl themselves.
As documented in bug 'win-process-acl-finesse', we've had enough
assorted complaints about it breaking various non-malicious pieces of
Windows process interaction (ranging from git->plink integration to
screen readers for the vision-impaired) that I think it's more
sensible to set the process back to its default level of protection.
This precaution was never a fully effective protection anyway, due to
the race condition at process startup; the only properly effective
defence would have been to prevent malware running under the same user
ID as PuTTY in the first place, so in that sense, nothing has changed.
But people who want the arguable defence-in-depth advantage of the ACL
restriction can now turn it on with the '-restrict-acl' command-line
option, and it's up to them whether they can live with the assorted
inconveniences that come with it.
In the course of this change, I've centralised a bit more of the
restriction code into winsecur.c, to avoid repeating the error
handling in multiple places.
This shows the build platform (32- vs 64-bit in particular, and also
whether Unix GTK builds were compiled with or without the X11 pieces),
what compiler was used to build the binary, and any interesting build
options that might have been set on the make command line (especially,
but not limited to, the security-damaging ones like NO_SECURITY or
UNPROTECT). This will probably be useful all over the place, but in
particular it should allow the different Windows binaries to be told
apart!
Commits 21101c739 and 2eb952ca3 laid the groundwork for this, by
allowing the various About boxes to contain free text and also
ensuring they could be copied and pasted easily as part of a bug
report.
The algorithm Windows uses to generate AppUserModelIDs "hangs on" to
removable media (CDs/DVDs) if PuTTY is launched with a CD/DVD in a drive.
Set the AppUserModelID explicitly to avoid using this algorithm.
At least on systems providing SetDefaultDllDirectories, this should
stop PuTTY from being willing to load DLLs from its containing
directory - which makes no difference when it's been properly
installed (in which case the application dir contains no DLLs anyway),
but does if it's being run from somewhere uncontrolled like a browser
downloads directory.
Preliminary testing suggests that this shouldn't break any existing
deliberate use of DLLs, including GSSAPI providers.
Commit f2e61275f introduced the use of uintptr_t, without adding an
include of <stdint.h> which is where the C standard says that type
should be defined. This didn't cause a build failure, because Visual
Studio also defines it in <stddef.h> which we do include. But a user
points out that other Windows toolchains - e.g. MinGW - don't
necessarily do the same.
I can't add an unconditional include of <stdint.h>, because the VS I
use for the current official builds doesn't have that header at all.
So I conditionalise it out for old VS; if it needs throwing out for
any other toolchain, I'll add further conditions as reports come in.
