2015-11-24 22:02:24 +00:00
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/*
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* wincapi.c: implementation of wincapi.h.
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*/
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#include "putty.h"
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#if !defined NO_SECURITY
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2019-12-31 07:42:02 +00:00
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#include "putty.h"
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#include "ssh.h"
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2015-11-24 22:02:24 +00:00
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#include "wincapi.h"
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2020-02-02 10:00:43 +00:00
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DEF_WINDOWS_FUNCTION(CryptProtectMemory);
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Convert a lot of 'int' variables to 'bool'.
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'!
2018-11-02 19:23:19 +00:00
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bool got_crypt(void)
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2015-11-24 22:02:24 +00:00
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{
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Convert a lot of 'int' variables to 'bool'.
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'!
2018-11-02 19:23:19 +00:00
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static bool attempted = false;
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static bool successful;
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2015-11-24 22:02:24 +00:00
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static HMODULE crypt;
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if (!attempted) {
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2018-10-29 19:50:29 +00:00
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attempted = true;
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2015-11-24 22:02:24 +00:00
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crypt = load_system32_dll("crypt32.dll");
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successful = crypt &&
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2017-06-20 18:02:48 +00:00
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#ifdef COVERITY
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/* The build toolchain I use with Coverity doesn't know
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* about this function, so can't type-check it */
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GET_WINDOWS_FUNCTION_NO_TYPECHECK(crypt, CryptProtectMemory)
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#else
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GET_WINDOWS_FUNCTION(crypt, CryptProtectMemory)
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#endif
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;
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2015-11-24 22:02:24 +00:00
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}
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return successful;
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}
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2019-12-31 07:42:02 +00:00
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#ifdef COVERITY
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/*
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* The hack I use to build for Coverity scanning, using winegcc and
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* Makefile.mgw, didn't provide some defines in wincrypt.h last time I
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* looked. Therefore, define them myself here, but enclosed in #ifdef
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* COVERITY to ensure I don't make up random nonsense values for any
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* real build.
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*/
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#ifndef CRYPTPROTECTMEMORY_BLOCK_SIZE
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#define CRYPTPROTECTMEMORY_BLOCK_SIZE 16
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#endif
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#ifndef CRYPTPROTECTMEMORY_CROSS_PROCESS
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#define CRYPTPROTECTMEMORY_CROSS_PROCESS 1
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#endif
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#endif
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char *capi_obfuscate_string(const char *realname)
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{
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char *cryptdata;
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int cryptlen;
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unsigned char digest[32];
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char retbuf[65];
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int i;
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cryptlen = strlen(realname) + 1;
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cryptlen += CRYPTPROTECTMEMORY_BLOCK_SIZE - 1;
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cryptlen /= CRYPTPROTECTMEMORY_BLOCK_SIZE;
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cryptlen *= CRYPTPROTECTMEMORY_BLOCK_SIZE;
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cryptdata = snewn(cryptlen, char);
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memset(cryptdata, 0, cryptlen);
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strcpy(cryptdata, realname);
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/*
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* CRYPTPROTECTMEMORY_CROSS_PROCESS causes CryptProtectMemory to
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* use the same key in all processes with this user id, meaning
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* that the next PuTTY process calling this function with the same
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* input will get the same data.
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*
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* (Contrast with CryptProtectData, which invents a new session
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* key every time since its API permits returning more data than
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* was input, so calling _that_ and hashing the output would not
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* be stable.)
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*
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* We don't worry too much if this doesn't work for some reason.
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* Omitting this step still has _some_ privacy value (in that
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* another user can test-hash things to confirm guesses as to
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* where you might be connecting to, but cannot invert SHA-256 in
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* the absence of any plausible guess). So we don't abort if we
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* can't call CryptProtectMemory at all, or if it fails.
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*/
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if (got_crypt())
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p_CryptProtectMemory(cryptdata, cryptlen,
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CRYPTPROTECTMEMORY_CROSS_PROCESS);
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/*
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* We don't want to give away the length of the hostname either,
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* so having got it back out of CryptProtectMemory we now hash it.
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*/
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hash_simple(&ssh_sha256, make_ptrlen(cryptdata, cryptlen), digest);
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sfree(cryptdata);
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/*
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* Finally, make printable.
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*/
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for (i = 0; i < 32; i++) {
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sprintf(retbuf + 2*i, "%02x", digest[i]);
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/* the last of those will also write the trailing NUL */
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}
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return dupstr(retbuf);
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}
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2015-11-24 22:02:24 +00:00
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#endif /* !defined NO_SECURITY */
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