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winpgnt.c: put all file-mapping code in one function.
Previously, the code to recover and memory-map the file-mapping object Pageant uses for its IPC, and the code to convey its contents to and from the cross-platform agent code, were widely separated, with the former living in the WM_COPYDATA handler in the window procedure, and the latter in answer_msg. Now all of that code lives in answer_filemapping_message; WndProc only handles the _window message_ contents - i.e. ensures the WM_COPYDATA message has the right dwData id and that its lpData contains an ASCIZ string - and answer_filemapping_message goes all the way from that file-mapping object name to calling pageant_handle_msg. While I'm here, I've also tidied up the code so that it uses the 'goto cleanup' idiom rather than nesting everything inconveniently deeply, and arranged that if anything goes wrong then we at least _construct_ an error message (although as yet we don't use that for anything unless we're compiled with DEBUG_IPC enabled).
This commit is contained in:
Simon Tatham
parent
20e8fdece3
commit
fecd42858c
@ -380,59 +380,6 @@ void keylist_update(void)
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}
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}
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struct PageantReply {
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char buf[AGENT_MAX_MSGLEN - 4];
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int len, overflowed;
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BinarySink_IMPLEMENTATION;
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};
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static void pageant_reply_BinarySink_write(
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BinarySink *bs, const void *data, size_t len)
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{
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struct PageantReply *rep = BinarySink_DOWNCAST(bs, struct PageantReply);
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if (!rep->overflowed && len <= sizeof(rep->buf) - rep->len) {
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memcpy(rep->buf + rep->len, data, len);
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rep->len += len;
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} else {
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rep->overflowed = TRUE;
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}
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}
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static void answer_msg(void *msgv)
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{
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unsigned char *msg = (unsigned char *)msgv;
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unsigned msglen;
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struct PageantReply reply;
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reply.len = 0;
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reply.overflowed = FALSE;
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BinarySink_INIT(&reply, pageant_reply_BinarySink_write);
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msglen = GET_32BIT(msg);
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if (msglen > AGENT_MAX_MSGLEN) {
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pageant_failure_msg(BinarySink_UPCAST(&reply),
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"incoming length field too large", NULL, NULL);
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} else {
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pageant_handle_msg(BinarySink_UPCAST(&reply),
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msg + 4, msglen, NULL, NULL);
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if (reply.len > AGENT_MAX_MSGLEN) {
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reply.len = 0;
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reply.overflowed = FALSE;
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pageant_failure_msg(BinarySink_UPCAST(&reply),
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"output would exceed max msglen", NULL, NULL);
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}
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}
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/*
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* Windows Pageant answers messages in place, by overwriting the
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* input message buffer.
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*/
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assert(4 + reply.len <= AGENT_MAX_MSGLEN);
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PUT_32BIT(msg, reply.len);
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memcpy(msg + 4, reply.buf, reply.len);
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smemclr(reply.buf, sizeof(reply.buf));
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}
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static void win_add_keyfile(Filename *filename)
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{
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char *err;
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@ -829,6 +776,168 @@ PSID get_default_sid(void)
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}
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#endif
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struct PageantReply {
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char buf[AGENT_MAX_MSGLEN - 4];
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int len, overflowed;
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BinarySink_IMPLEMENTATION;
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};
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static void pageant_reply_BinarySink_write(
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BinarySink *bs, const void *data, size_t len)
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{
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struct PageantReply *rep = BinarySink_DOWNCAST(bs, struct PageantReply);
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if (!rep->overflowed && len <= sizeof(rep->buf) - rep->len) {
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memcpy(rep->buf + rep->len, data, len);
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rep->len += len;
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} else {
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rep->overflowed = TRUE;
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}
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}
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static char *answer_filemapping_message(const char *mapname)
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{
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HANDLE maphandle = INVALID_HANDLE_VALUE;
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void *mapaddr = NULL;
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char *err = NULL;
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unsigned char *msg;
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unsigned msglen;
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struct PageantReply reply;
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#ifndef NO_SECURITY
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PSID mapsid = NULL;
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PSID expectedsid = NULL;
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PSID expectedsid_bc = NULL;
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PSECURITY_DESCRIPTOR psd = NULL;
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#endif
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#ifdef DEBUG_IPC
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debug(("mapname = \"%s\"\n", mapname));
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#endif
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maphandle = OpenFileMapping(FILE_MAP_ALL_ACCESS, FALSE, mapname);
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if (maphandle == NULL || maphandle == INVALID_HANDLE_VALUE) {
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err = dupprintf("OpenFileMapping(\"%s\"): %s",
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mapname, win_strerror(GetLastError()));
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goto cleanup;
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}
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#ifdef DEBUG_IPC
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debug(("maphandle = %p\n", maphandle));
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#endif
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#ifndef NO_SECURITY
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if (has_security) {
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DWORD retd;
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if ((expectedsid = get_user_sid()) == NULL) {
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err = dupstr("unable to get user SID");
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goto cleanup;
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}
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if ((expectedsid_bc = get_default_sid()) == NULL) {
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err = dupstr("unable to get default SID");
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goto cleanup;
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}
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if ((retd = p_GetSecurityInfo(
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maphandle, SE_KERNEL_OBJECT, OWNER_SECURITY_INFORMATION,
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&mapsid, NULL, NULL, NULL, &psd) != ERROR_SUCCESS)) {
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err = dupprintf("unable to get owner of file mapping: "
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"GetSecurityInfo returned: %s",
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win_strerror(retd));
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goto cleanup;
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}
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#ifdef DEBUG_IPC
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{
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LPTSTR ours, ours2, theirs;
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ConvertSidToStringSid(mapsid, &theirs);
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ConvertSidToStringSid(expectedsid, &ours);
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ConvertSidToStringSid(expectedsid_bc, &ours2);
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debug(("got sids:\n oursnew=%s\n oursold=%s\n"
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" theirs=%s\n", ours, ours2, theirs));
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LocalFree(ours);
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LocalFree(ours2);
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LocalFree(theirs);
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}
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#endif
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if (!EqualSid(mapsid, expectedsid) &&
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!EqualSid(mapsid, expectedsid_bc)) {
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err = dupstr("wrong owning SID of file mapping");
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goto cleanup;
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}
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} else
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#endif /* NO_SECURITY */
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{
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#ifdef DEBUG_IPC
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debug(("security APIs not present\n"));
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#endif
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}
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mapaddr = MapViewOfFile(maphandle, FILE_MAP_WRITE, 0, 0, 0);
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if (!mapaddr) {
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err = dupprintf("unable to obtain view of file mapping: %s",
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win_strerror(GetLastError()));
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goto cleanup;
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}
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#ifdef DEBUG_IPC
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debug(("mapped address = %p\n", mapaddr));
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#endif
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msglen = GET_32BIT((unsigned char *)mapaddr);
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#ifdef DEBUG_IPC
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debug(("msg length=%08x, msg type=%02x\n",
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msglen, (unsigned)((unsigned char *) mapaddr)[4]));
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#endif
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reply.len = 0;
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reply.overflowed = FALSE;
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BinarySink_INIT(&reply, pageant_reply_BinarySink_write);
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if (msglen > AGENT_MAX_MSGLEN - 4) {
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pageant_failure_msg(BinarySink_UPCAST(&reply),
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"incoming length field too large", NULL, NULL);
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} else {
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pageant_handle_msg(BinarySink_UPCAST(&reply),
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msg + 4, msglen, NULL, NULL);
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if (reply.overflowed || reply.len > AGENT_MAX_MSGLEN - 4) {
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reply.len = 0;
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reply.overflowed = FALSE;
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pageant_failure_msg(BinarySink_UPCAST(&reply),
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"output would overflow message buffer",
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NULL, NULL);
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}
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}
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if (reply.len > AGENT_MAX_MSGLEN - 4) {
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err = dupstr("even error-message output overflows buffer");
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goto cleanup;
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}
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/*
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* Windows Pageant answers messages in place, by overwriting the
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* input message buffer.
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*/
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assert(4 + reply.len <= AGENT_MAX_MSGLEN);
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PUT_32BIT(msg, reply.len);
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memcpy(msg + 4, reply.buf, reply.len);
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smemclr(reply.buf, sizeof(reply.buf));
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cleanup:
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/* expectedsid has the lifetime of the program, so we don't free it */
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sfree(expectedsid_bc);
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if (psd)
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LocalFree(psd);
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if (mapaddr)
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UnmapViewOfFile(mapaddr);
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if (maphandle != NULL && maphandle != INVALID_HANDLE_VALUE)
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CloseHandle(maphandle);
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return err;
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}
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static LRESULT CALLBACK WndProc(HWND hwnd, UINT message,
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WPARAM wParam, LPARAM lParam)
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{
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@ -971,14 +1080,7 @@ static LRESULT CALLBACK WndProc(HWND hwnd, UINT message,
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case WM_COPYDATA:
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{
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COPYDATASTRUCT *cds;
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char *mapname;
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void *p;
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HANDLE filemap;
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#ifndef NO_SECURITY
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PSID mapowner, ourself, ourself2;
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#endif
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PSECURITY_DESCRIPTOR psd = NULL;
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int ret = 0;
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char *mapname, *err;
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cds = (COPYDATASTRUCT *) lParam;
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if (cds->dwData != AGENT_COPYDATA_ID)
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@ -986,92 +1088,15 @@ static LRESULT CALLBACK WndProc(HWND hwnd, UINT message,
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mapname = (char *) cds->lpData;
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if (mapname[cds->cbData - 1] != '\0')
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return 0; /* failure to be ASCIZ! */
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err = answer_filemapping_message(mapname);
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if (err) {
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#ifdef DEBUG_IPC
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debug(("mapname is :%s:\n", mapname));
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debug(("IPC failed: %s\n", err));
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#endif
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filemap = OpenFileMapping(FILE_MAP_ALL_ACCESS, FALSE, mapname);
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#ifdef DEBUG_IPC
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debug(("filemap is %p\n", filemap));
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#endif
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if (filemap != NULL && filemap != INVALID_HANDLE_VALUE) {
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#ifndef NO_SECURITY
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int rc;
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if (has_security) {
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if ((ourself = get_user_sid()) == NULL) {
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#ifdef DEBUG_IPC
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debug(("couldn't get user SID\n"));
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#endif
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CloseHandle(filemap);
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return 0;
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}
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if ((ourself2 = get_default_sid()) == NULL) {
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#ifdef DEBUG_IPC
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debug(("couldn't get default SID\n"));
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#endif
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CloseHandle(filemap);
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return 0;
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}
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if ((rc = p_GetSecurityInfo(filemap, SE_KERNEL_OBJECT,
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OWNER_SECURITY_INFORMATION,
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&mapowner, NULL, NULL, NULL,
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&psd) != ERROR_SUCCESS)) {
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#ifdef DEBUG_IPC
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debug(("couldn't get owner info for filemap: %d\n",
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rc));
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#endif
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CloseHandle(filemap);
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sfree(ourself2);
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return 0;
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}
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#ifdef DEBUG_IPC
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{
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LPTSTR ours, ours2, theirs;
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ConvertSidToStringSid(mapowner, &theirs);
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ConvertSidToStringSid(ourself, &ours);
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ConvertSidToStringSid(ourself2, &ours2);
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debug(("got sids:\n oursnew=%s\n oursold=%s\n"
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" theirs=%s\n", ours, ours2, theirs));
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LocalFree(ours);
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LocalFree(ours2);
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LocalFree(theirs);
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}
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#endif
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if (!EqualSid(mapowner, ourself) &&
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!EqualSid(mapowner, ourself2)) {
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CloseHandle(filemap);
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LocalFree(psd);
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sfree(ourself2);
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return 0; /* security ID mismatch! */
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}
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#ifdef DEBUG_IPC
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debug(("security stuff matched\n"));
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#endif
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LocalFree(psd);
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sfree(ourself2);
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} else {
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#ifdef DEBUG_IPC
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debug(("security APIs not present\n"));
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#endif
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}
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#endif
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p = MapViewOfFile(filemap, FILE_MAP_WRITE, 0, 0, 0);
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#ifdef DEBUG_IPC
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debug(("p is %p\n", p));
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{
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int i;
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for (i = 0; i < 5; i++)
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debug(("p[%d]=%02x\n", i,
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((unsigned char *) p)[i]));
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}
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#endif
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answer_msg(p);
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ret = 1;
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UnmapViewOfFile(p);
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}
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CloseHandle(filemap);
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return ret;
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sfree(err);
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return 0;
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}
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return 1;
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}
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}
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