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Merge pull request #550 from falemagn/pull-reqs/cf9e96e_Add_a_state_f…
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…or_the_receiving_of_SFTP_init_message

Support partial packet reads during the SFTP server-side initialization.
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@JacobBarthelmeh
JacobBarthelmeh authored Aug 3, 2023
2 parents 67de4fd + 975b145 commit 864ef1e
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Showing 2 changed files with 98 additions and 39 deletions.
135 changes: 96 additions & 39 deletions src/wolfsftp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -63,6 +63,7 @@ enum WS_SFTP_STATE_ID {
STATE_ID_RECV = 0x10000,
STATE_ID_CHMOD = 0x20000,
STATE_ID_SETATR = 0x40000,
STATE_ID_RECV_INIT = 0x80000,
};

enum WS_SFTP_CHMOD_STATE_ID {
Expand Down Expand Up @@ -239,6 +240,11 @@ typedef struct WS_SFTP_LS_STATE {
} WS_SFTP_LS_STATE;


typedef struct WS_SFTP_RECV_INIT_STATE {
WS_SFTP_BUFFER buffer;
word32 extSz;
} WS_SFTP_RECV_INIT_STATE;

enum WS_SFTP_GET_STATE_ID {
STATE_GET_INIT,
STATE_GET_LSTAT,
Expand Down Expand Up @@ -762,6 +768,14 @@ static void wolfSSH_SFTP_ClearState(WOLFSSH* ssh, enum WS_SFTP_STATE_ID state)
ssh->setatrState = NULL;
}
}

if (state & STATE_ID_RECV_INIT) {
if (ssh->recvInitState) {
wolfSSH_SFTP_buffer_free(ssh, &ssh->recvInitState->buffer);
WFREE(ssh->recvInitState, ssh->ctx->heap, DYNTYPE_SFTP_STATE);
ssh->recvInitState = NULL;
}
}
}
}

Expand Down Expand Up @@ -987,49 +1001,85 @@ static int SFTP_GetAttributes_Handle(WOLFSSH* ssh, byte* handle, int handleSz,
* returns WS_SUCCESS on success
*/
static int SFTP_ServerRecvInit(WOLFSSH* ssh) {
int len;
enum {
RECV_INIT_SIZE = LENGTH_SZ + MSG_ID_SZ + UINT32_SZ
};

int ret;
byte id;
word32 sz = 0;
word32 version = 0;
byte buf[LENGTH_SZ + MSG_ID_SZ + UINT32_SZ];
WS_SFTP_RECV_INIT_STATE *state;

if ((len = wolfSSH_stream_read(ssh, buf, sizeof(buf))) != sizeof(buf)) {
return len;
state = ssh->recvInitState;
if (state == NULL) {
state = (WS_SFTP_RECV_INIT_STATE*)WMALLOC(sizeof(WS_SFTP_RECV_INIT_STATE),
ssh->ctx->heap, DYNTYPE_SFTP_STATE);
if (state == NULL) {
ssh->error = WS_MEMORY_E;
return WS_FATAL_ERROR;
}
WMEMSET(state, 0, sizeof(WS_SFTP_RECV_INIT_STATE));
ssh->recvInitState = state;
}

if (SFTP_GetSz(buf, &sz,
MSG_ID_SZ + UINT32_SZ, WOLFSSH_MAX_SFTP_RECV) != WS_SUCCESS) {
wolfSSH_SFTP_ClearState(ssh, STATE_ID_ALL);
return WS_BUFFER_E;
}
switch (ssh->sftpState) {
case SFTP_BEGIN:
ret = wolfSSH_SFTP_buffer_read(ssh, &state->buffer, RECV_INIT_SIZE);
if (ret < 0) {
return WS_FATAL_ERROR;
}

/* compare versions supported */
id = buf[LENGTH_SZ];
if (id != WOLFSSH_FTP_INIT) {
WLOG(WS_LOG_SFTP, "Unexpected SFTP type received");
wolfSSH_SFTP_ClearState(ssh, STATE_ID_ALL);
return WS_BUFFER_E;
}
if (ret < WOLFSSH_SFTP_HEADER) {
WLOG(WS_LOG_SFTP, "Unable to read SFTP INIT message");
return WS_FATAL_ERROR;
}

ato32(buf + LENGTH_SZ + MSG_ID_SZ, &version);
/* versions greater than WOLFSSH_SFTP_VERSION should fall back to ours
* versions less than WOLFSSH_SFTP_VERSION we should bail out on or
* implement a fall back */
if (version < WOLFSSH_SFTP_VERSION) {
WLOG(WS_LOG_SFTP, "Unsupported SFTP version, sending version 3");
wolfSSH_SFTP_ClearState(ssh, STATE_ID_ALL);
return WS_VERSION_E;
}
if (SFTP_GetSz(state->buffer.data, &sz,
MSG_ID_SZ + UINT32_SZ, WOLFSSH_MAX_SFTP_RECV) != WS_SUCCESS) {
wolfSSH_SFTP_ClearState(ssh, STATE_ID_ALL);
return WS_BUFFER_E;
}

/* silently ignore extensions if not supported */
sz = sz - MSG_ID_SZ - UINT32_SZ;
if (sz > 0) {
byte* data = (byte*)WMALLOC(sz, NULL, DYNTYPE_BUFFER);
if (data == NULL) return WS_MEMORY_E;
len = wolfSSH_stream_read(ssh, data, sz);
WFREE(data, NULL, DYNTYPE_BUFFER);
if (len != (int)sz)
return len;
/* compare versions supported */
id = state->buffer.data[LENGTH_SZ];
if (id != WOLFSSH_FTP_INIT) {
WLOG(WS_LOG_SFTP, "Unexpected SFTP type received");
wolfSSH_SFTP_ClearState(ssh, STATE_ID_ALL);
return WS_BUFFER_E;
}

ato32(state->buffer.data + LENGTH_SZ + MSG_ID_SZ, &version);
/* versions greater than WOLFSSH_SFTP_VERSION should fall back to ours
* versions less than WOLFSSH_SFTP_VERSION we should bail out on or
* implement a fall back */
if (version < WOLFSSH_SFTP_VERSION) {
WLOG(WS_LOG_SFTP, "Unsupported SFTP version, sending version 3");
wolfSSH_SFTP_ClearState(ssh, STATE_ID_ALL);
return WS_VERSION_E;
}

wolfSSH_SFTP_buffer_free(ssh, &state->buffer);

state->extSz = sz - MSG_ID_SZ - UINT32_SZ;
ssh->sftpState = SFTP_EXT;
NO_BREAK;

case SFTP_EXT:
/* silently ignore extensions if not supported */
if (state->extSz > 0) {
ret = wolfSSH_SFTP_buffer_read(ssh, &state->buffer, (int)state->extSz);
if (ret < 0) {
return WS_FATAL_ERROR;
}

if (ret < (int)state->extSz) {
WLOG(WS_LOG_SFTP, "Unable to read SFTP INIT extensions");
return WS_FATAL_ERROR;
}

wolfSSH_SFTP_buffer_free(ssh, &state->buffer);
}
}

ssh->reqId++;
Expand Down Expand Up @@ -1063,7 +1113,7 @@ static int SFTP_ServerSendInit(WOLFSSH* ssh) {
*/
int wolfSSH_SFTP_accept(WOLFSSH* ssh)
{
int ret = WS_SFTP_COMPLETE;
int ret = WS_FATAL_ERROR;

if (ssh == NULL) {
return WS_BAD_ARGUMENT;
Expand All @@ -1090,18 +1140,25 @@ int wolfSSH_SFTP_accept(WOLFSSH* ssh)

switch (ssh->sftpState) {
case SFTP_BEGIN:
if (SFTP_ServerRecvInit(ssh) != WS_SUCCESS) {
return WS_FATAL_ERROR;
case SFTP_EXT:
ret = SFTP_ServerRecvInit(ssh);
if (ret != WS_SUCCESS) {
if (ssh->error != WS_WANT_READ && ssh->error != WS_WANT_WRITE)
wolfSSH_SFTP_ClearState(ssh, STATE_ID_ALL);
return ret;
}
ssh->sftpState = SFTP_RECV;
NO_BREAK;

case SFTP_RECV:
if (SFTP_ServerSendInit(ssh) != WS_SUCCESS) {
return WS_FATAL_ERROR;
ret = SFTP_ServerSendInit(ssh);
if (ret != WS_SUCCESS) {
return ret;
}
ssh->sftpState = SFTP_DONE;
WLOG(WS_LOG_SFTP, "SFTP connection established");
wolfSSH_SFTP_ClearState(ssh, STATE_ID_RECV_INIT);
ret = WS_SFTP_COMPLETE;
break;

default:
Expand Down
2 changes: 2 additions & 0 deletions wolfssh/internal.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -581,6 +581,7 @@ typedef struct SFTP_OFST {
char to[WOLFSSH_MAX_FILENAME];
} SFTP_OFST;

struct WS_SFTP_RECV_INIT_STATE;
struct WS_SFTP_GET_STATE;
struct WS_SFTP_PUT_STATE;
struct WS_SFTP_LSTAT_STATE;
Expand Down Expand Up @@ -761,6 +762,7 @@ struct WOLFSSH {
#ifdef WOLFSSH_STOREHANDLE
WS_HANDLE_LIST* handleList;
#endif
struct WS_SFTP_RECV_INIT_STATE* recvInitState;
struct WS_SFTP_RECV_STATE* recvState;
struct WS_SFTP_RMDIR_STATE* rmdirState;
struct WS_SFTP_MKDIR_STATE* mkdirState;
Expand Down

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