diff options
| -rw-r--r-- | lib/urldata.h | 3 | ||||
| -rw-r--r-- | lib/vtls/schannel.c | 268 | ||||
| -rw-r--r-- | lib/vtls/schannel.h | 1 |
3 files changed, 186 insertions, 86 deletions
diff --git a/lib/urldata.h b/lib/urldata.h index 64b855e32..05bda794b 100644 --- a/lib/urldata.h +++ b/lib/urldata.h @@ -322,6 +322,9 @@ struct ssl_connect_data { size_t encdata_offset, decdata_offset; unsigned char *encdata_buffer, *decdata_buffer; unsigned long req_flags, ret_flags; + CURLcode recv_unrecoverable_err; /* schannel_recv had an unrecoverable err */ + bool recv_sspi_close_notify; /* true if connection closed by close_notify */ + bool recv_connection_closed; /* true if connection closed, regardless how */ #endif /* USE_SCHANNEL */ #ifdef USE_DARWINSSL SSLContextRef ssl_ctx; diff --git a/lib/vtls/schannel.c b/lib/vtls/schannel.c index 543c20657..19aff8f07 100644 --- a/lib/vtls/schannel.c +++ b/lib/vtls/schannel.c @@ -268,6 +268,10 @@ schannel_connect_step1(struct connectdata *conn, int sockindex) infof(data, "schannel: sent initial handshake data: " "sent %zd bytes\n", written); + connssl->recv_unrecoverable_err = CURLE_OK; + connssl->recv_sspi_close_notify = false; + connssl->recv_connection_closed = false; + /* continue to second handshake step */ connssl->connecting_state = ssl_connect_2; @@ -300,6 +304,17 @@ schannel_connect_step2(struct connectdata *conn, int sockindex) if(!connssl->cred || !connssl->ctxt) return CURLE_SSL_CONNECT_ERROR; + /* buffer to store previously received and decrypted data */ + if(connssl->decdata_buffer == NULL) { + connssl->decdata_offset = 0; + connssl->decdata_length = CURL_SCHANNEL_BUFFER_INIT_SIZE; + connssl->decdata_buffer = malloc(connssl->decdata_length); + if(connssl->decdata_buffer == NULL) { + failf(data, "schannel: unable to allocate memory"); + return CURLE_OUT_OF_MEMORY; + } + } + /* buffer to store previously received and encrypted data */ if(connssl->encdata_buffer == NULL) { connssl->encdata_offset = 0; @@ -834,8 +849,7 @@ schannel_recv(struct connectdata *conn, int sockindex, char *buf, size_t len, CURLcode *err) { size_t size = 0; - ssize_t nread = 0; - CURLcode result; + ssize_t nread = -1; struct SessionHandle *data = conn->data; struct ssl_connect_data *connssl = &conn->ssl[sockindex]; unsigned char *reallocated_buffer; @@ -844,72 +858,103 @@ schannel_recv(struct connectdata *conn, int sockindex, SecBuffer inbuf[4]; SecBufferDesc inbuf_desc; SECURITY_STATUS sspi_status = SEC_E_OK; + /* we want the length of the encrypted buffer to be at least large enough + that it can hold all the bytes requested and some TLS record overhead. */ + size_t min_encdata_length = len + CURL_SCHANNEL_BUFFER_FREE_SIZE; + + /**************************************************************************** + * Don't return or set connssl->recv_unrecoverable_err unless in the cleanup. + * The pattern for return error is set *err, optional infof, goto cleanup. + * + * Our priority is to always return as much decrypted data to the caller as + * possible, even if an error occurs. The state of the decrypted buffer must + * always be valid. Transfer of decrypted data to the caller's buffer is + * handled in the cleanup. + */ infof(data, "schannel: client wants to read %zu bytes\n", len); *err = CURLE_OK; - /* buffer to store previously received and decrypted data */ - if(connssl->decdata_buffer == NULL) { - connssl->decdata_offset = 0; - connssl->decdata_length = CURL_SCHANNEL_BUFFER_INIT_SIZE; - connssl->decdata_buffer = malloc(connssl->decdata_length); - if(connssl->decdata_buffer == NULL) { - failf(data, "schannel: unable to allocate memory"); - *err = CURLE_OUT_OF_MEMORY; - return -1; - } + if(len && len <= connssl->decdata_offset) { + infof(data, "schannel: enough decrypted data is already available\n"); + goto cleanup; } + else if(connssl->recv_unrecoverable_err) { + *err = connssl->recv_unrecoverable_err; + infof(data, "schannel: an unrecoverable error occurred in a prior call\n"); + goto cleanup; + } + else if(connssl->recv_sspi_close_notify) { + /* once a server has indicated shutdown there is no more encrypted data */ + infof(data, "schannel: server indicated shutdown in a prior call\n"); + goto cleanup; + } + else if(!len) { + /* It's debatable what to return when !len. Regardless we can't return + immediately because there may be data to decrypt (in the case we want to + decrypt all encrypted cached data) so handle !len later in cleanup. + */ + ; /* do nothing */ + } + else if(!connssl->recv_connection_closed) { + /* increase enc buffer in order to fit the requested amount of data */ + size = connssl->encdata_length - connssl->encdata_offset; + if(size < CURL_SCHANNEL_BUFFER_FREE_SIZE || + connssl->encdata_length < min_encdata_length) { + reallocated_length = connssl->encdata_offset + + CURL_SCHANNEL_BUFFER_FREE_SIZE; + if(reallocated_length < min_encdata_length) { + reallocated_length = min_encdata_length; + } + reallocated_buffer = realloc(connssl->encdata_buffer, + reallocated_length); + if(reallocated_buffer == NULL) { + *err = CURLE_OUT_OF_MEMORY; + failf(data, "schannel: unable to re-allocate memory"); + goto cleanup; + } - /* increase buffer in order to fit the requested amount of data */ - if(connssl->encdata_length - connssl->encdata_offset < - CURL_SCHANNEL_BUFFER_FREE_SIZE || connssl->encdata_length < len) { - /* increase internal encrypted data buffer */ - reallocated_length = connssl->encdata_offset + - CURL_SCHANNEL_BUFFER_FREE_SIZE; - /* make sure that the requested amount of data fits */ - if(reallocated_length < len) { - reallocated_length = len; - } - reallocated_buffer = realloc(connssl->encdata_buffer, - reallocated_length); - - if(reallocated_buffer == NULL) { - failf(data, "schannel: unable to re-allocate memory"); - *err = CURLE_OUT_OF_MEMORY; - return -1; - } - else { connssl->encdata_buffer = reallocated_buffer; connssl->encdata_length = reallocated_length; + size = connssl->encdata_length - connssl->encdata_offset; + infof(data, "schannel: encdata_buffer resized %zu\n", + connssl->encdata_length); } - } - /* read encrypted data from socket */ - infof(data, "schannel: encrypted data buffer: offset %zu length %zu\n", - connssl->encdata_offset, connssl->encdata_length); - size = connssl->encdata_length - connssl->encdata_offset; - if(size > 0) { + infof(data, "schannel: encrypted data buffer: offset %zu length %zu\n", + connssl->encdata_offset, connssl->encdata_length); + + /* read encrypted data from socket */ *err = Curl_read_plain(conn->sock[sockindex], - (char *) (connssl->encdata_buffer + - connssl->encdata_offset), + (char *)(connssl->encdata_buffer + + connssl->encdata_offset), size, &nread); - /* check for received data */ - if(*err != CURLE_OK) { - return -1; + if(*err) { + nread = -1; + if(*err == CURLE_AGAIN) + infof(data, "schannel: Curl_read_plain returned CURLE_AGAIN\n"); + else if(*err == CURLE_RECV_ERROR) + infof(data, "schannel: Curl_read_plain returned CURLE_RECV_ERROR\n"); + else + infof(data, "schannel: Curl_read_plain returned error %d\n", *err); + } + else if(nread == 0) { + connssl->recv_connection_closed = true; + infof(data, "schannel: server closed the connection\n"); } else if(nread > 0) { - /* increase encrypted data buffer offset */ - connssl->encdata_offset += nread; + connssl->encdata_offset += (size_t)nread; + infof(data, "schannel: encrypted data got %zd\n", nread); } - infof(data, "schannel: encrypted data got %zd\n", nread); } infof(data, "schannel: encrypted data buffer: offset %zu length %zu\n", connssl->encdata_offset, connssl->encdata_length); - /* check if we still have some data in our buffers */ + /* decrypt loop */ while(connssl->encdata_offset > 0 && sspi_status == SEC_E_OK && - connssl->decdata_offset < len) { + (!len || connssl->decdata_offset < len || + connssl->recv_connection_closed)) { /* prepare data buffer for DecryptMessage call */ InitSecBuffer(&inbuf[0], SECBUFFER_DATA, connssl->encdata_buffer, curlx_uztoul(connssl->encdata_offset)); @@ -924,13 +969,6 @@ schannel_recv(struct connectdata *conn, int sockindex, sspi_status = s_pSecFn->DecryptMessage(&connssl->ctxt->ctxt_handle, &inbuf_desc, 0, NULL); - /* check if we need more data */ - if(sspi_status == SEC_E_INCOMPLETE_MESSAGE) { - infof(data, "schannel: failed to decrypt data, need more data\n"); - *err = CURLE_AGAIN; - return -1; - } - /* check if everything went fine (server may want to renegotiate or shutdown the connection context) */ if(sspi_status == SEC_E_OK || sspi_status == SEC_I_RENEGOTIATE || @@ -943,7 +981,7 @@ schannel_recv(struct connectdata *conn, int sockindex, /* increase buffer in order to fit the received amount of data */ size = inbuf[1].cbBuffer > CURL_SCHANNEL_BUFFER_FREE_SIZE ? - inbuf[1].cbBuffer : CURL_SCHANNEL_BUFFER_FREE_SIZE; + inbuf[1].cbBuffer : CURL_SCHANNEL_BUFFER_FREE_SIZE; if(connssl->decdata_length - connssl->decdata_offset < size || connssl->decdata_length < len) { /* increase internal decrypted data buffer */ @@ -954,21 +992,18 @@ schannel_recv(struct connectdata *conn, int sockindex, } reallocated_buffer = realloc(connssl->decdata_buffer, reallocated_length); - if(reallocated_buffer == NULL) { - failf(data, "schannel: unable to re-allocate memory"); *err = CURLE_OUT_OF_MEMORY; - return -1; - } - else { - connssl->decdata_buffer = reallocated_buffer; - connssl->decdata_length = reallocated_length; + failf(data, "schannel: unable to re-allocate memory"); + goto cleanup; } + connssl->decdata_buffer = reallocated_buffer; + connssl->decdata_length = reallocated_length; } /* copy decrypted data to internal buffer */ size = inbuf[1].cbBuffer; - if(size > 0) { + if(size) { memcpy(connssl->decdata_buffer + connssl->decdata_offset, inbuf[1].pvBuffer, size); connssl->decdata_offset += size; @@ -1007,56 +1042,117 @@ schannel_recv(struct connectdata *conn, int sockindex, /* check if server wants to renegotiate the connection context */ if(sspi_status == SEC_I_RENEGOTIATE) { infof(data, "schannel: remote party requests renegotiation\n"); - + if(*err && *err != CURLE_AGAIN) { + infof(data, "schannel: can't renogotiate, an error is pending\n"); + goto cleanup; + } + if(connssl->encdata_offset) { + *err = CURLE_RECV_ERROR; + infof(data, "schannel: can't renogotiate, " + "encrypted data available\n"); + goto cleanup; + } /* begin renegotiation */ infof(data, "schannel: renegotiating SSL/TLS connection\n"); connssl->state = ssl_connection_negotiating; connssl->connecting_state = ssl_connect_2_writing; - result = schannel_connect_common(conn, sockindex, FALSE, &done); - if(result) - *err = result; - else { - infof(data, "schannel: SSL/TLS connection renegotiated\n"); - /* now retry receiving data */ - return schannel_recv(conn, sockindex, buf, len, err); + *err = schannel_connect_common(conn, sockindex, FALSE, &done); + if(*err) { + infof(data, "schannel: renegotiation failed\n"); + goto cleanup; } + /* now retry receiving data */ + sspi_status = SEC_E_OK; + infof(data, "schannel: SSL/TLS connection renegotiated\n"); + continue; } + /* check if the server closed the connection */ + else if(sspi_status == SEC_I_CONTEXT_EXPIRED) { + /* In Windows 2000 SEC_I_CONTEXT_EXPIRED (close_notify) is not + returned so we have to work around that in cleanup. */ + connssl->recv_sspi_close_notify = true; + if(!connssl->recv_connection_closed) { + connssl->recv_connection_closed = true; + infof(data, "schannel: server closed the connection\n"); + } + goto cleanup; + } + } + else if(sspi_status == SEC_E_INCOMPLETE_MESSAGE) { + if(!*err) + *err = CURLE_AGAIN; + infof(data, "schannel: failed to decrypt data, need more data\n"); + goto cleanup; } else { - /* something went wrong and we need to return an error */ + *err = CURLE_RECV_ERROR; infof(data, "schannel: failed to read data from server: %s\n", Curl_sspi_strerror(conn, sspi_status)); - *err = CURLE_RECV_ERROR; - return -1; + goto cleanup; } } + infof(data, "schannel: encrypted data buffer: offset %zu length %zu\n", + connssl->encdata_offset, connssl->encdata_length); + infof(data, "schannel: decrypted data buffer: offset %zu length %zu\n", connssl->decdata_offset, connssl->decdata_length); - /* copy requested decrypted data to supplied buffer */ +cleanup: + /* Warning- there is no guarantee the encdata state is valid at this point */ + infof(data, "schannel: schannel_recv cleanup\n"); + + /* Error if the connection has closed without a close_notify. + Behavior here is a matter of debate. We don't want to be vulnerable to a + truncation attack however there's some browser precedent for ignoring the + close_notify for compatibility reasons. + Additionally, Windows 2000 (v5.0) is a special case since it seems it doesn't + return close_notify. In that case if the connection was closed we assume it + was graceful (close_notify) since there doesn't seem to be a way to tell. + */ + if(len && !connssl->decdata_offset && connssl->recv_connection_closed && + !connssl->recv_sspi_close_notify) { + DWORD winver_full, winver_major, winver_minor; + winver_full = GetVersion(); + winver_major = (DWORD)(LOBYTE(LOWORD(winver_full))); + winver_minor = (DWORD)(HIBYTE(LOWORD(winver_full))); + + if(winver_major == 5 && winver_minor == 0 && sspi_status == SEC_E_OK) + connssl->recv_sspi_close_notify = true; + else { + *err = CURLE_RECV_ERROR; + infof(data, "schannel: server closed abruptly (missing close_notify)\n"); + } + } + + /* Any error other than CURLE_AGAIN is an unrecoverable error. */ + if(*err && *err != CURLE_AGAIN) + connssl->recv_unrecoverable_err = *err; + size = len < connssl->decdata_offset ? len : connssl->decdata_offset; - if(size > 0) { + if(size) { memcpy(buf, connssl->decdata_buffer, size); - - /* move remaining decrypted data forward to the beginning of buffer */ memmove(connssl->decdata_buffer, connssl->decdata_buffer + size, connssl->decdata_offset - size); connssl->decdata_offset -= size; - infof(data, "schannel: decrypted data returned %zd\n", size); + infof(data, "schannel: decrypted data returned %zu\n", size); infof(data, "schannel: decrypted data buffer: offset %zu length %zu\n", connssl->decdata_offset, connssl->decdata_length); - } - /* check if the server closed the connection, */ - /* including special check for Windows 2000 Professional */ - else if(sspi_status == SEC_I_CONTEXT_EXPIRED || (sspi_status == SEC_E_OK && - connssl->encdata_offset && connssl->encdata_buffer[0] == 0x15)) { - infof(data, "schannel: server closed the connection\n"); *err = CURLE_OK; + return (ssize_t)size; } - return size; + if(!*err && !connssl->recv_connection_closed) + *err = CURLE_AGAIN; + + /* It's debatable what to return when !len. We could return whatever error we + got from decryption but instead we override here so the return is consistent. + */ + if(!len) + *err = CURLE_OK; + + return *err ? -1 : 0; } CURLcode diff --git a/lib/vtls/schannel.h b/lib/vtls/schannel.h index e019a8606..532958483 100644 --- a/lib/vtls/schannel.h +++ b/lib/vtls/schannel.h @@ -72,6 +72,7 @@ #define SECBUFFER_ALERT 17 #endif +/* Both schannel buffer sizes must be > 0 */ #define CURL_SCHANNEL_BUFFER_INIT_SIZE 4096 #define CURL_SCHANNEL_BUFFER_FREE_SIZE 1024 |