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Ignore padding when an iovector is supplied

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The iSCSI protocol adds padding to a data packet if the data size is not
a multiple of four.  The iovector provided by QEMU does not include such
padding, and libiscsi then complains that there was a protocol error.
This patch fixes this by reading the padding in a separate "recv"
system call.  These packets anyway do not happen in the data path,
where the packet size is a multiple of 512.

This fixes QEMU's scsi-generic backend, which triggered the problem when
the target sent a 66-byte INQUIRY response.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini
2013-08-26 17:54:47 +02:00
parent daac72a8f9
commit 73b0d4777f
3 changed files with 51 additions and 11 deletions
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48
lib/socket.c
View File

@@ -482,7 +482,7 @@ static int
iscsi_read_from_socket(struct iscsi_context *iscsi)
{
struct iscsi_in_pdu *in;
ssize_t data_size, count;
ssize_t data_size, count, padding_size;
if (iscsi->incoming == NULL) {
iscsi->incoming = iscsi_szmalloc(iscsi, sizeof(struct iscsi_in_pdu));
@@ -519,31 +519,36 @@ iscsi_read_from_socket(struct iscsi_context *iscsi)
return 0;
}
data_size = iscsi_get_pdu_data_size(&in->hdr[0]);
padding_size = iscsi_get_pdu_padding_size(&in->hdr[0]);
data_size = iscsi_get_pdu_data_size(&in->hdr[0]) + padding_size;
if (data_size < 0 || data_size > (ssize_t)iscsi->initiator_max_recv_data_segment_length) {
iscsi_set_error(iscsi, "Invalid data size received from target (%d)", (int)data_size);
return -1;
}
if (data_size != 0) {
unsigned char *buf = NULL;
unsigned char padding_buf[3];
unsigned char *buf = padding_buf;
struct scsi_iovector * iovector_in;
count = data_size - in->data_pos;
/* first try to see if we already have a user buffer */
iovector_in = iscsi_get_scsi_task_iovector_in(iscsi, in);
if (iovector_in != NULL) {
if (iovector_in != NULL && count > padding_size) {
uint32_t offset = scsi_get_uint32(&in->hdr[40]);
count = iscsi_iovector_readv_writev(iscsi, iovector_in, in->data_pos + offset, count, 0);
count = iscsi_iovector_readv_writev(iscsi, iovector_in, in->data_pos + offset, count - padding_size, 0);
} else {
if (in->data == NULL) {
in->data = iscsi_malloc(iscsi, data_size);
if (iovector_in == NULL) {
if (in->data == NULL) {
iscsi_set_error(iscsi, "Out-of-memory: failed to malloc iscsi_in_pdu->data(%d)", (int)data_size);
return -1;
in->data = iscsi_malloc(iscsi, data_size);
if (in->data == NULL) {
iscsi_set_error(iscsi, "Out-of-memory: failed to malloc iscsi_in_pdu->data(%d)", (int)data_size);
return -1;
}
}
buf = &in->data[in->data_pos];
}
buf = &in->data[in->data_pos];
count = recv(iscsi->fd, buf, count, 0);
}
@@ -588,7 +593,9 @@ static int
iscsi_write_to_socket(struct iscsi_context *iscsi)
{
ssize_t count;
size_t total;
struct iscsi_pdu *pdu;
static char padding_buf[3];
if (iscsi->fd == -1) {
iscsi_set_error(iscsi, "trying to write but not connected");
@@ -664,6 +671,27 @@ iscsi_write_to_socket(struct iscsi_context *iscsi)
pdu->payload_written += count;
}
total = pdu->payload_len;
total = (total + 3) & 0xfffffffc;
/* Write padding */
if (pdu->payload_written < total) {
count = send(iscsi->fd, padding_buf, total - pdu->payload_written, 0);
if (count == -1) {
if (errno == EAGAIN || errno == EWOULDBLOCK) {
return 0;
}
iscsi_set_error(iscsi, "Error when writing to "
"socket :%d", errno);
return -1;
}
pdu->payload_written += count;
}
/* if we havent written the full padding yet. */
if (pdu->payload_written != total) {
return 0;
}
if (pdu->flags & ISCSI_PDU_DELETE_WHEN_SENT) {
iscsi_free_pdu(iscsi, pdu);
}