Move the dynamic loading of advapi into its own module.

There's now a winsecur.[ch], which centralises helper functions using
the Windows security stuff in advapi.h (currently just get_user_sid),
and also centralises the run-time loading of those functions and
checking they're all there.

[originally from svn r10082]

Recipe

@@ -300,7 +300,7 @@ SSH      = ssh sshcrc sshdes sshmd5 sshrsa sshrand sshsha sshblowf
          + sshdh sshcrcda sshpubk sshzlib sshdss x11fwd portfwd
          + sshaes sshsh256 sshsh512 sshbn wildcard pinger ssharcf
          + sshgssc pgssapi
-WINSSH   = SSH winnoise winpgntc wingss winhsock errsock
+WINSSH   = SSH winnoise winsecur winpgntc wingss winhsock errsock
 UXSSH    = SSH uxnoise uxagentc uxgss
 
 # SFTP implementation (pscp, psftp).
@@ -350,8 +350,8 @@ psftp    : [C] psftp winsftp wincons WINSSH BE_SSH SFTP wildcard WINMISC
          + psftp.res winnojmp LIBS
 
 pageant  : [G] winpgnt sshrsa sshpubk sshdes sshbn sshmd5 version tree234
-         + misc sshaes sshsha winpgntc sshdss sshsh256 sshsh512 winutils
+         + misc sshaes sshsha winsecur winpgntc sshdss sshsh256 sshsh512
-         + winmisc winhelp conf pageant.res LIBS
+	 + winutils winmisc winhelp conf pageant.res LIBS
 
 puttygen : [G] winpgen sshrsag sshdssg sshprime sshdes sshbn sshmd5 version
          + sshrand winnoise sshsha winstore misc winctrls sshrsa sshdss winmisc

windows/winnpc.c

@@ -14,7 +14,7 @@
 
 #if !defined NO_SECURITY
 
-#include <aclapi.h>
+#include "winsecur.h"
 
 Socket make_handle_socket(HANDLE send_H, HANDLE recv_H, Plug plug,
                           int overlapped);
@@ -27,9 +27,6 @@ Socket new_named_pipe_client(const char *pipename, Plug plug)
     char *err;
     Socket ret;
 
-    extern int advapi_initialised;
-    init_advapi();           /* for get_user_sid. FIXME: do better. */
-
     assert(strncmp(pipename, "\\\\.\\pipe\\", 9) == 0);
     assert(strchr(pipename + 9, '\\') == NULL);
 

windows/winpgnt.c

@@ -14,6 +14,7 @@
 #include "ssh.h"
 #include "misc.h"
 #include "tree234.h"
+#include "winsecur.h"
 
 #include <shellapi.h>
 
@@ -2065,7 +2066,7 @@ int WINAPI WinMain(HINSTANCE inst, HINSTANCE prev, LPSTR cmdline, int show)
 	/*
 	 * Attempt to get the security API we need.
 	 */
-        if (!init_advapi()) {
+        if (!got_advapi()) {
 	    MessageBox(NULL,
 		       "Unable to access security APIs. Pageant will\n"
 		       "not run, in case it causes a security breach.",

windows/winpgntc.c

@@ -8,7 +8,7 @@
 #include "putty.h"
 
 #ifndef NO_SECURITY
-#include <aclapi.h>
+#include "winsecur.h"
 #endif
 
 #define AGENT_COPYDATA_ID 0x804e50ba   /* random goop */
@@ -70,88 +70,6 @@ DWORD WINAPI agent_query_thread(LPVOID param)
 
 #endif
 
-/*
- * Dynamically load advapi32.dll for SID manipulation. In its absence,
- * we degrade gracefully.
- */
-#ifndef NO_SECURITY
-int advapi_initialised = FALSE;
-static HMODULE advapi;
-DECL_WINDOWS_FUNCTION(static, BOOL, OpenProcessToken,
-		      (HANDLE, DWORD, PHANDLE));
-DECL_WINDOWS_FUNCTION(static, BOOL, GetTokenInformation,
-		      (HANDLE, TOKEN_INFORMATION_CLASS,
-                       LPVOID, DWORD, PDWORD));
-DECL_WINDOWS_FUNCTION(static, BOOL, InitializeSecurityDescriptor,
-		      (PSECURITY_DESCRIPTOR, DWORD));
-DECL_WINDOWS_FUNCTION(static, BOOL, SetSecurityDescriptorOwner,
-		      (PSECURITY_DESCRIPTOR, PSID, BOOL));
-DECL_WINDOWS_FUNCTION(, DWORD, GetSecurityInfo,
-		      (HANDLE, SE_OBJECT_TYPE, SECURITY_INFORMATION,
-		       PSID *, PSID *, PACL *, PACL *,
-		       PSECURITY_DESCRIPTOR *));
-int init_advapi(void)
-{
-    advapi = load_system32_dll("advapi32.dll");
-    return advapi &&
-	GET_WINDOWS_FUNCTION(advapi, GetSecurityInfo) &&
-        GET_WINDOWS_FUNCTION(advapi, OpenProcessToken) &&
-	GET_WINDOWS_FUNCTION(advapi, GetTokenInformation) &&
-	GET_WINDOWS_FUNCTION(advapi, InitializeSecurityDescriptor) &&
-	GET_WINDOWS_FUNCTION(advapi, SetSecurityDescriptorOwner);
-}
-
-PSID get_user_sid(void)
-{
-    HANDLE proc = NULL, tok = NULL;
-    TOKEN_USER *user = NULL;
-    DWORD toklen, sidlen;
-    PSID sid = NULL, ret = NULL;
-
-    if ((proc = OpenProcess(MAXIMUM_ALLOWED, FALSE,
-                            GetCurrentProcessId())) == NULL)
-        goto cleanup;
-
-    if (!p_OpenProcessToken(proc, TOKEN_QUERY, &tok))
-        goto cleanup;
-
-    if (!p_GetTokenInformation(tok, TokenUser, NULL, 0, &toklen) &&
-        GetLastError() != ERROR_INSUFFICIENT_BUFFER)
-        goto cleanup;
-
-    if ((user = (TOKEN_USER *)LocalAlloc(LPTR, toklen)) == NULL)
-        goto cleanup;
-
-    if (!p_GetTokenInformation(tok, TokenUser, user, toklen, &toklen))
-        goto cleanup;
-
-    sidlen = GetLengthSid(user->User.Sid);
-
-    sid = (PSID)smalloc(sidlen);
-
-    if (!CopySid(sidlen, sid, user->User.Sid))
-        goto cleanup;
-
-    /* Success. Move sid into the return value slot, and null it out
-     * to stop the cleanup code freeing it. */
-    ret = sid;
-    sid = NULL;
-
-  cleanup:
-    if (proc != NULL)
-        CloseHandle(proc);
-    if (tok != NULL)
-        CloseHandle(tok);
-    if (user != NULL)
-        LocalFree(user);
-    if (sid != NULL)
-        sfree(sid);
-
-    return ret;
-}
-
-#endif
-
 int agent_query(void *in, int inlen, void **out, int *outlen,
 		void (*callback)(void *, void *, int), void *callback_ctx)
 {
@@ -175,7 +93,7 @@ int agent_query(void *in, int inlen, void **out, int *outlen,
 
     psa = NULL;
 #ifndef NO_SECURITY
-    if (advapi_initialised || init_advapi()) {
+    if (got_advapi()) {
         /*
          * Make the file mapping we create for communication with
          * Pageant owned by the user SID rather than the default. This

windows/winsecur.c

@@ -0,0 +1,86 @@
+/*
+ * winsecur.c: implementation of winsecur.h.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "putty.h"
+
+#if !defined NO_SECURITY
+
+#define WINSECUR_GLOBAL
+#include "winsecur.h"
+
+int got_advapi(void)
+{
+    static int attempted = FALSE;
+    static int successful;
+    static HMODULE advapi;
+
+    if (!attempted) {
+        attempted = TRUE;
+        advapi = load_system32_dll("advapi32.dll");
+        successful = advapi &&
+            GET_WINDOWS_FUNCTION(advapi, GetSecurityInfo) &&
+            GET_WINDOWS_FUNCTION(advapi, OpenProcessToken) &&
+            GET_WINDOWS_FUNCTION(advapi, GetTokenInformation) &&
+            GET_WINDOWS_FUNCTION(advapi, InitializeSecurityDescriptor) &&
+            GET_WINDOWS_FUNCTION(advapi, SetSecurityDescriptorOwner);
+    }
+    return successful;
+}
+
+PSID get_user_sid(void)
+{
+    HANDLE proc = NULL, tok = NULL;
+    TOKEN_USER *user = NULL;
+    DWORD toklen, sidlen;
+    PSID sid = NULL, ret = NULL;
+
+    if (!got_advapi())
+        goto cleanup;
+
+    if ((proc = OpenProcess(MAXIMUM_ALLOWED, FALSE,
+                            GetCurrentProcessId())) == NULL)
+        goto cleanup;
+
+    if (!p_OpenProcessToken(proc, TOKEN_QUERY, &tok))
+        goto cleanup;
+
+    if (!p_GetTokenInformation(tok, TokenUser, NULL, 0, &toklen) &&
+        GetLastError() != ERROR_INSUFFICIENT_BUFFER)
+        goto cleanup;
+
+    if ((user = (TOKEN_USER *)LocalAlloc(LPTR, toklen)) == NULL)
+        goto cleanup;
+
+    if (!p_GetTokenInformation(tok, TokenUser, user, toklen, &toklen))
+        goto cleanup;
+
+    sidlen = GetLengthSid(user->User.Sid);
+
+    sid = (PSID)smalloc(sidlen);
+
+    if (!CopySid(sidlen, sid, user->User.Sid))
+        goto cleanup;
+
+    /* Success. Move sid into the return value slot, and null it out
+     * to stop the cleanup code freeing it. */
+    ret = sid;
+    sid = NULL;
+
+  cleanup:
+    if (proc != NULL)
+        CloseHandle(proc);
+    if (tok != NULL)
+        CloseHandle(tok);
+    if (user != NULL)
+        LocalFree(user);
+    if (sid != NULL)
+        sfree(sid);
+
+    return ret;
+}
+
+#endif /* !defined NO_SECURITY */

windows/winsecur.h

@@ -0,0 +1,32 @@
+/*
+ * winsecur.h: some miscellaneous security-related helper functions,
+ * defined in winsecur.c, that use the advapi32 library. Also
+ * centralises the machinery for dynamically loading that library.
+ */
+
+#if !defined NO_SECURITY
+
+#include <aclapi.h>
+
+#ifndef WINSECUR_GLOBAL
+#define WINSECUR_GLOBAL extern
+#endif
+
+DECL_WINDOWS_FUNCTION(WINSECUR_GLOBAL, BOOL, OpenProcessToken,
+		      (HANDLE, DWORD, PHANDLE));
+DECL_WINDOWS_FUNCTION(WINSECUR_GLOBAL, BOOL, GetTokenInformation,
+		      (HANDLE, TOKEN_INFORMATION_CLASS,
+                       LPVOID, DWORD, PDWORD));
+DECL_WINDOWS_FUNCTION(WINSECUR_GLOBAL, BOOL, InitializeSecurityDescriptor,
+		      (PSECURITY_DESCRIPTOR, DWORD));
+DECL_WINDOWS_FUNCTION(WINSECUR_GLOBAL, BOOL, SetSecurityDescriptorOwner,
+		      (PSECURITY_DESCRIPTOR, PSID, BOOL));
+DECL_WINDOWS_FUNCTION(WINSECUR_GLOBAL, DWORD, GetSecurityInfo,
+		      (HANDLE, SE_OBJECT_TYPE, SECURITY_INFORMATION,
+		       PSID *, PSID *, PACL *, PACL *,
+		       PSECURITY_DESCRIPTOR *));
+
+int got_advapi(void);
+PSID get_user_sid(void);
+
+#endif

windows/winstuff.h

@@ -516,14 +516,6 @@ void agent_schedule_callback(void (*callback)(void *, void *, int),
 			     void *callback_ctx, void *data, int len);
 #define FLAG_SYNCAGENT 0x1000
 
-/*
- * winpgntc.c also exports these two functions which are used by the
- * server side of Pageant as well, to get the user SID for comparing
- * with clients'.
- */
-int init_advapi(void);  /* initialises everything needed by get_user_sid */
-PSID get_user_sid(void);
-
 /*
  * Exports from winser.c.
  */