* [PATCH] net: ncsi: Adding padding bytes in the payload
@ 2021-10-12 6:22 Kumar Thangavel
2021-10-12 8:02 ` Paul Menzel
2021-10-12 22:44 ` Joel Stanley
0 siblings, 2 replies; 4+ messages in thread
From: Kumar Thangavel @ 2021-10-12 6:22 UTC (permalink / raw)
To: Samuel Mendoza-Jonas, David S. Miller, Jakub Kicinski
Cc: netdev, linux-kernel, openbmc, linux-aspeed, patrickw3,
Amithash Prasad, velumanit
Update NC-SI command handler (both standard and OEM) to take into
account of payload paddings in allocating skb (in case of payload
size is not 32-bit aligned).
The checksum field follows payload field, without taking payload
padding into account can cause checksum being truncated, leading to
dropped packets.
Signed-off-by: Kumar Thangavel <thangavel.k@hcl.com>
---
net/ncsi/ncsi-cmd.c | 21 +++++++++++++++++----
1 file changed, 17 insertions(+), 4 deletions(-)
diff --git a/net/ncsi/ncsi-cmd.c b/net/ncsi/ncsi-cmd.c
index ba9ae482141b..4625fc935603 100644
--- a/net/ncsi/ncsi-cmd.c
+++ b/net/ncsi/ncsi-cmd.c
@@ -214,11 +214,19 @@ static int ncsi_cmd_handler_oem(struct sk_buff *skb,
struct ncsi_cmd_oem_pkt *cmd;
unsigned int len;
+ /* NC-SI spec requires payload to be padded with 0
+ * to 32-bit boundary before the checksum field.
+ * Ensure the padding bytes are accounted for in
+ * skb allocation
+ */
+
+ unsigned short payload = ALIGN(nca->payload, 4);
+
len = sizeof(struct ncsi_cmd_pkt_hdr) + 4;
- if (nca->payload < 26)
+ if (payload < 26)
len += 26;
else
- len += nca->payload;
+ len += payload;
cmd = skb_put_zero(skb, len);
memcpy(&cmd->mfr_id, nca->data, nca->payload);
@@ -272,6 +280,7 @@ static struct ncsi_request *ncsi_alloc_command(struct ncsi_cmd_arg *nca)
struct net_device *dev = nd->dev;
int hlen = LL_RESERVED_SPACE(dev);
int tlen = dev->needed_tailroom;
+ int payload;
int len = hlen + tlen;
struct sk_buff *skb;
struct ncsi_request *nr;
@@ -281,14 +290,18 @@ static struct ncsi_request *ncsi_alloc_command(struct ncsi_cmd_arg *nca)
return NULL;
/* NCSI command packet has 16-bytes header, payload, 4 bytes checksum.
+ * Payload needs padding so that the checksum field follwoing payload is
+ * aligned to 32bit boundary.
* The packet needs padding if its payload is less than 26 bytes to
* meet 64 bytes minimal ethernet frame length.
*/
len += sizeof(struct ncsi_cmd_pkt_hdr) + 4;
- if (nca->payload < 26)
+
+ payload = ALIGN(nca->payload, 4);
+ if (payload < 26)
len += 26;
else
- len += nca->payload;
+ len += payload;
/* Allocate skb */
skb = alloc_skb(len, GFP_ATOMIC);
--
2.17.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] net: ncsi: Adding padding bytes in the payload
2021-10-12 6:22 [PATCH] net: ncsi: Adding padding bytes in the payload Kumar Thangavel
@ 2021-10-12 8:02 ` Paul Menzel
2021-10-12 22:44 ` Joel Stanley
1 sibling, 0 replies; 4+ messages in thread
From: Paul Menzel @ 2021-10-12 8:02 UTC (permalink / raw)
To: Kumar Thangavel
Cc: Samuel Mendoza-Jonas, David S. Miller, Jakub Kicinski,
linux-aspeed, netdev, openbmc, Amithash Prasad, linux-kernel,
velumanit, patrickw3
Dear Kumar,
Thank you for your patch.
Nit: Could you please use the imperative mood in the commit message summary:
> net: ncsi: Add padding bytes in the payload
Or more descriptive:
> net: ncsi: Padd payload to be 32-bit aligned to fix dropped packets
Am 12.10.21 um 08:22 schrieb Kumar Thangavel:
> Update NC-SI command handler (both standard and OEM) to take into
> account of payload paddings in allocating skb (in case of payload
> size is not 32-bit aligned).
>
> The checksum field follows payload field, without taking payload
> padding into account can cause checksum being truncated, leading to
> dropped packets.
How can this be reproduced?
> Signed-off-by: Kumar Thangavel <thangavel.k@hcl.com>
>
> ---
> net/ncsi/ncsi-cmd.c | 21 +++++++++++++++++----
> 1 file changed, 17 insertions(+), 4 deletions(-)
>
> diff --git a/net/ncsi/ncsi-cmd.c b/net/ncsi/ncsi-cmd.c
> index ba9ae482141b..4625fc935603 100644
> --- a/net/ncsi/ncsi-cmd.c
> +++ b/net/ncsi/ncsi-cmd.c
> @@ -214,11 +214,19 @@ static int ncsi_cmd_handler_oem(struct sk_buff *skb,
> struct ncsi_cmd_oem_pkt *cmd;
> unsigned int len;
>
> + /* NC-SI spec requires payload to be padded with 0
It’d be great, if you included the specification version, and section if
the requirement.
> + * to 32-bit boundary before the checksum field.
> + * Ensure the padding bytes are accounted for in
> + * skb allocation
> + */
> +
Please remove the blank line.
> + unsigned short payload = ALIGN(nca->payload, 4);
> +
> len = sizeof(struct ncsi_cmd_pkt_hdr) + 4;
> - if (nca->payload < 26)
> + if (payload < 26)
> len += 26;
> else
> - len += nca->payload;
> + len += payload;
>
> cmd = skb_put_zero(skb, len);
> memcpy(&cmd->mfr_id, nca->data, nca->payload);
> @@ -272,6 +280,7 @@ static struct ncsi_request *ncsi_alloc_command(struct ncsi_cmd_arg *nca)
> struct net_device *dev = nd->dev;
> int hlen = LL_RESERVED_SPACE(dev);
> int tlen = dev->needed_tailroom;
> + int payload;
> int len = hlen + tlen;
> struct sk_buff *skb;
> struct ncsi_request *nr;
> @@ -281,14 +290,18 @@ static struct ncsi_request *ncsi_alloc_command(struct ncsi_cmd_arg *nca)
> return NULL;
>
> /* NCSI command packet has 16-bytes header, payload, 4 bytes checksum.
> + * Payload needs padding so that the checksum field follwoing payload is
following
> + * aligned to 32bit boundary.
32-bit
> * The packet needs padding if its payload is less than 26 bytes to
> * meet 64 bytes minimal ethernet frame length.
> */
> len += sizeof(struct ncsi_cmd_pkt_hdr) + 4;
> - if (nca->payload < 26)
> +
> + payload = ALIGN(nca->payload, 4);
> + if (payload < 26)
> len += 26;
> else
> - len += nca->payload;
> + len += payload;
>
> /* Allocate skb */
> skb = alloc_skb(len, GFP_ATOMIC);
>
Besides the nits, this looks fine to me.
Kind regards,
Paul
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] net: ncsi: Adding padding bytes in the payload
2021-10-12 6:22 [PATCH] net: ncsi: Adding padding bytes in the payload Kumar Thangavel
2021-10-12 8:02 ` Paul Menzel
@ 2021-10-12 22:44 ` Joel Stanley
2021-10-13 2:46 ` Samuel Mendoza-Jonas
1 sibling, 1 reply; 4+ messages in thread
From: Joel Stanley @ 2021-10-12 22:44 UTC (permalink / raw)
To: Kumar Thangavel
Cc: Samuel Mendoza-Jonas, David S. Miller, Jakub Kicinski,
linux-aspeed, Networking, OpenBMC Maillist, Amithash Prasad,
Linux Kernel Mailing List, velumanit, patrickw3
On Tue, 12 Oct 2021 at 06:23, Kumar Thangavel
<kumarthangavel.hcl@gmail.com> wrote:
>
> Update NC-SI command handler (both standard and OEM) to take into
> account of payload paddings in allocating skb (in case of payload
> size is not 32-bit aligned).
>
> The checksum field follows payload field, without taking payload
> padding into account can cause checksum being truncated, leading to
> dropped packets.
Can you help us review this by pointing out where this is described in
the NCSI spec?
We've been running this code for a number of years now and I wonder
why this hasn't been a problem so far.
Cheers,
Joel
>
> Signed-off-by: Kumar Thangavel <thangavel.k@hcl.com>
>
> ---
> net/ncsi/ncsi-cmd.c | 21 +++++++++++++++++----
> 1 file changed, 17 insertions(+), 4 deletions(-)
>
> diff --git a/net/ncsi/ncsi-cmd.c b/net/ncsi/ncsi-cmd.c
> index ba9ae482141b..4625fc935603 100644
> --- a/net/ncsi/ncsi-cmd.c
> +++ b/net/ncsi/ncsi-cmd.c
> @@ -214,11 +214,19 @@ static int ncsi_cmd_handler_oem(struct sk_buff *skb,
> struct ncsi_cmd_oem_pkt *cmd;
> unsigned int len;
>
> + /* NC-SI spec requires payload to be padded with 0
> + * to 32-bit boundary before the checksum field.
> + * Ensure the padding bytes are accounted for in
> + * skb allocation
> + */
> +
> + unsigned short payload = ALIGN(nca->payload, 4);
> +
> len = sizeof(struct ncsi_cmd_pkt_hdr) + 4;
> - if (nca->payload < 26)
> + if (payload < 26)
> len += 26;
> else
> - len += nca->payload;
> + len += payload;
>
> cmd = skb_put_zero(skb, len);
> memcpy(&cmd->mfr_id, nca->data, nca->payload);
> @@ -272,6 +280,7 @@ static struct ncsi_request *ncsi_alloc_command(struct ncsi_cmd_arg *nca)
> struct net_device *dev = nd->dev;
> int hlen = LL_RESERVED_SPACE(dev);
> int tlen = dev->needed_tailroom;
> + int payload;
> int len = hlen + tlen;
> struct sk_buff *skb;
> struct ncsi_request *nr;
> @@ -281,14 +290,18 @@ static struct ncsi_request *ncsi_alloc_command(struct ncsi_cmd_arg *nca)
> return NULL;
>
> /* NCSI command packet has 16-bytes header, payload, 4 bytes checksum.
> + * Payload needs padding so that the checksum field follwoing payload is
> + * aligned to 32bit boundary.
> * The packet needs padding if its payload is less than 26 bytes to
> * meet 64 bytes minimal ethernet frame length.
> */
> len += sizeof(struct ncsi_cmd_pkt_hdr) + 4;
> - if (nca->payload < 26)
> +
> + payload = ALIGN(nca->payload, 4);
> + if (payload < 26)
> len += 26;
> else
> - len += nca->payload;
> + len += payload;
>
> /* Allocate skb */
> skb = alloc_skb(len, GFP_ATOMIC);
> --
> 2.17.1
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] net: ncsi: Adding padding bytes in the payload
2021-10-12 22:44 ` Joel Stanley
@ 2021-10-13 2:46 ` Samuel Mendoza-Jonas
0 siblings, 0 replies; 4+ messages in thread
From: Samuel Mendoza-Jonas @ 2021-10-13 2:46 UTC (permalink / raw)
To: Joel Stanley, Kumar Thangavel
Cc: David S. Miller, Jakub Kicinski, linux-aspeed, Networking,
OpenBMC Maillist, Amithash Prasad, Linux Kernel Mailing List,
velumanit, patrickw3
On Tue, 2021-10-12 at 22:44 +0000, Joel Stanley wrote:
> On Tue, 12 Oct 2021 at 06:23, Kumar Thangavel
> <kumarthangavel.hcl@gmail.com> wrote:
> >
> > Update NC-SI command handler (both standard and OEM) to take into
> > account of payload paddings in allocating skb (in case of payload
> > size is not 32-bit aligned).
> >
> > The checksum field follows payload field, without taking payload
> > padding into account can cause checksum being truncated, leading to
> > dropped packets.
>
> Can you help us review this by pointing out where this is described in
> the NCSI spec?
>
> We've been running this code for a number of years now and I wonder
> why this hasn't been a problem so far.
I'm assuming this is referencing section 8.2.2.2:
If the payload is present and does not end on a 32-bit boundary, one to
three padding bytes equal to 0x00 shall be present to align the
checksum field to a 32-bit boundary.
But I'm also surprised this hasn't caused issues so far if we've been
getting it wrong. Is there an example that reproduces the issue?
Cheers,
Sam
>
> Cheers,
>
> Joel
>
> >
> > Signed-off-by: Kumar Thangavel <thangavel.k@hcl.com>
> >
> > ---
> > net/ncsi/ncsi-cmd.c | 21 +++++++++++++++++----
> > 1 file changed, 17 insertions(+), 4 deletions(-)
> >
> > diff --git a/net/ncsi/ncsi-cmd.c b/net/ncsi/ncsi-cmd.c
> > index ba9ae482141b..4625fc935603 100644
> > --- a/net/ncsi/ncsi-cmd.c
> > +++ b/net/ncsi/ncsi-cmd.c
> > @@ -214,11 +214,19 @@ static int ncsi_cmd_handler_oem(struct sk_buff
> > *skb,
> > struct ncsi_cmd_oem_pkt *cmd;
> > unsigned int len;
> >
> > + /* NC-SI spec requires payload to be padded with 0
> > + * to 32-bit boundary before the checksum field.
> > + * Ensure the padding bytes are accounted for in
> > + * skb allocation
> > + */
> > +
> > + unsigned short payload = ALIGN(nca->payload, 4);
> > +
> > len = sizeof(struct ncsi_cmd_pkt_hdr) + 4;
> > - if (nca->payload < 26)
> > + if (payload < 26)
> > len += 26;
> > else
> > - len += nca->payload;
> > + len += payload;
> >
> > cmd = skb_put_zero(skb, len);
> > memcpy(&cmd->mfr_id, nca->data, nca->payload);
> > @@ -272,6 +280,7 @@ static struct ncsi_request
> > *ncsi_alloc_command(struct ncsi_cmd_arg *nca)
> > struct net_device *dev = nd->dev;
> > int hlen = LL_RESERVED_SPACE(dev);
> > int tlen = dev->needed_tailroom;
> > + int payload;
> > int len = hlen + tlen;
> > struct sk_buff *skb;
> > struct ncsi_request *nr;
> > @@ -281,14 +290,18 @@ static struct ncsi_request
> > *ncsi_alloc_command(struct ncsi_cmd_arg *nca)
> > return NULL;
> >
> > /* NCSI command packet has 16-bytes header, payload, 4 bytes
> > checksum.
> > + * Payload needs padding so that the checksum field follwoing
> > payload is
> > + * aligned to 32bit boundary.
> > * The packet needs padding if its payload is less than 26
> > bytes to
> > * meet 64 bytes minimal ethernet frame length.
> > */
> > len += sizeof(struct ncsi_cmd_pkt_hdr) + 4;
> > - if (nca->payload < 26)
> > +
> > + payload = ALIGN(nca->payload, 4);
> > + if (payload < 26)
> > len += 26;
> > else
> > - len += nca->payload;
> > + len += payload;
> >
> > /* Allocate skb */
> > skb = alloc_skb(len, GFP_ATOMIC);
> > --
> > 2.17.1
> >
^ permalink raw reply [flat|nested] 4+ messages in thread
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2021-10-12 6:22 [PATCH] net: ncsi: Adding padding bytes in the payload Kumar Thangavel
2021-10-12 8:02 ` Paul Menzel
2021-10-12 22:44 ` Joel Stanley
2021-10-13 2:46 ` Samuel Mendoza-Jonas
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