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Create, and use for all loads of system DLLs, a wrapper function

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called load_system32_dll() which constructs a full pathname for the
DLL using GetSystemDirectory.

The only DLL load not covered by this change is the one for
gssapi32.dll, because that one's not in the system32 directory.

[originally from svn r8993]
This commit is contained in:
Simon Tatham
2010-09-13 08:29:45 +00:00
parent 75f1d3ed94
commit 9f274bed91
8 changed files with 37 additions and 9 deletions
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29
windows/winmisc.c
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@ -49,7 +49,7 @@ char *get_username(void)
static int tried_usernameex = FALSE;
if (!tried_usernameex) {
/* Not available on Win9x, so load dynamically */
HMODULE secur32 = LoadLibrary("SECUR32.DLL");
HMODULE secur32 = load_system32_dll("secur32.dll");
GET_WINDOWS_FUNCTION(secur32, GetUserNameExA);
tried_usernameex = TRUE;
}
@ -105,6 +105,33 @@ BOOL init_winver(void)
return GetVersionEx ( (OSVERSIONINFO *) &osVersion);
}
HMODULE load_system32_dll(const char *libname)
{
/*
* Wrapper function to load a DLL out of c:\windows\system32
* without going through the full DLL search path. (Hence no
* attack is possible by placing a substitute DLL earlier on that
* path.)
*/
static char *sysdir = NULL;
char *fullpath;
HMODULE ret;
if (!sysdir) {
int size = 0, len;
do {
size = 3*size/2 + 512;
sysdir = sresize(sysdir, size, char);
len = GetSystemDirectory(sysdir, size);
} while (len >= size);
}
fullpath = dupcat(sysdir, "\\", libname, NULL);
ret = LoadLibrary(fullpath);
sfree(fullpath);
return ret;
}
#ifdef DEBUG
static FILE *debug_fp = NULL;
static HANDLE debug_hdl = INVALID_HANDLE_VALUE;