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net: cdc_ncm: splitting rx_fixup for code reuse

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Verifying and handling received MBIM and NCM frames will need
to be different in three areas:
 - verifying the NDP signature
 - checking valid datagram length
 - datagram header manipulation

This makes it inconvenient to share rx_fixup in whole.  But
some verification parts are common.  Split these out in separate
functions.

Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Bjørn Mork 2012-10-22 10:56:33 +00:00 committed by David S. Miller
parent 75d67d354f
commit ff06ab13a4
1 changed files with 55 additions and 28 deletions
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83
drivers/net/usb/cdc_ncm.c
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@ -966,19 +966,12 @@ cdc_ncm_tx_fixup(struct usbnet *dev, struct sk_buff *skb, gfp_t flags)
return NULL;
}
static int cdc_ncm_rx_fixup(struct usbnet *dev, struct sk_buff *skb_in)
/* verify NTB header and return offset of first NDP, or negative error */
static int cdc_ncm_rx_verify_nth16(struct cdc_ncm_ctx *ctx, struct sk_buff *skb_in)
{
struct sk_buff *skb;
struct cdc_ncm_ctx *ctx = (struct cdc_ncm_ctx *)dev->data[0];
int len;
int nframes;
int x;
int offset;
struct usb_cdc_ncm_nth16 *nth16;
struct usb_cdc_ncm_ndp16 *ndp16;
struct usb_cdc_ncm_dpe16 *dpe16;
int ndpoffset;
int loopcount = 50; /* arbitrary max preventing infinite loop */
int len;
int ret = -EINVAL;
if (ctx == NULL)
goto error;
@ -1012,40 +1005,74 @@ static int cdc_ncm_rx_fixup(struct usbnet *dev, struct sk_buff *skb_in)
}
ctx->rx_seq = le16_to_cpu(nth16->wSequence);
ndpoffset = le16_to_cpu(nth16->wNdpIndex);
next_ndp:
ret = le16_to_cpu(nth16->wNdpIndex);
error:
return ret;
}
/* verify NDP header and return number of datagrams, or negative error */
static int cdc_ncm_rx_verify_ndp16(struct sk_buff *skb_in, int ndpoffset)
{
struct usb_cdc_ncm_ndp16 *ndp16;
int ret = -EINVAL;
if ((ndpoffset + sizeof(struct usb_cdc_ncm_ndp16)) > skb_in->len) {
pr_debug("invalid NDP offset <%u>\n", ndpoffset);
goto error;
}
ndp16 = (struct usb_cdc_ncm_ndp16 *)(skb_in->data + ndpoffset);
if (le32_to_cpu(ndp16->dwSignature) != USB_CDC_NCM_NDP16_NOCRC_SIGN) {
pr_debug("invalid DPT16 signature <%u>\n",
le32_to_cpu(ndp16->dwSignature));
goto err_ndp;
}
if (le16_to_cpu(ndp16->wLength) < USB_CDC_NCM_NDP16_LENGTH_MIN) {
pr_debug("invalid DPT16 length <%u>\n",
le32_to_cpu(ndp16->dwSignature));
goto err_ndp;
goto error;
}
nframes = ((le16_to_cpu(ndp16->wLength) -
ret = ((le16_to_cpu(ndp16->wLength) -
sizeof(struct usb_cdc_ncm_ndp16)) /
sizeof(struct usb_cdc_ncm_dpe16));
nframes--; /* we process NDP entries except for the last one */
ret--; /* we process NDP entries except for the last one */
ndpoffset += sizeof(struct usb_cdc_ncm_ndp16);
if ((ndpoffset + nframes * (sizeof(struct usb_cdc_ncm_dpe16))) >
if ((sizeof(struct usb_cdc_ncm_ndp16) + ret * (sizeof(struct usb_cdc_ncm_dpe16))) >
skb_in->len) {
pr_debug("Invalid nframes = %d\n", nframes);
goto err_ndp;
pr_debug("Invalid nframes = %d\n", ret);
ret = -EINVAL;
}
dpe16 = (struct usb_cdc_ncm_dpe16 *)(skb_in->data + ndpoffset);
error:
return ret;
}
static int cdc_ncm_rx_fixup(struct usbnet *dev, struct sk_buff *skb_in)
{
struct sk_buff *skb;
struct cdc_ncm_ctx *ctx = (struct cdc_ncm_ctx *)dev->data[0];
int len;
int nframes;
int x;
int offset;
struct usb_cdc_ncm_ndp16 *ndp16;
struct usb_cdc_ncm_dpe16 *dpe16;
int ndpoffset;
int loopcount = 50; /* arbitrary max preventing infinite loop */
ndpoffset = cdc_ncm_rx_verify_nth16(ctx, skb_in);
if (ndpoffset < 0)
goto error;
next_ndp:
nframes = cdc_ncm_rx_verify_ndp16(skb_in, ndpoffset);
if (nframes < 0)
goto error;
ndp16 = (struct usb_cdc_ncm_ndp16 *)(skb_in->data + ndpoffset);
if (le32_to_cpu(ndp16->dwSignature) != USB_CDC_NCM_NDP16_NOCRC_SIGN) {
pr_debug("invalid DPT16 signature <%u>\n",
le32_to_cpu(ndp16->dwSignature));
goto err_ndp;
}
dpe16 = ndp16->dpe16;
for (x = 0; x < nframes; x++, dpe16++) {
offset = le16_to_cpu(dpe16->wDatagramIndex);