| Message ID | 20211012062240.GA5761@gmail.com |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | net: ncsi: Adding padding bytes in the payload | expand |
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
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 >
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 > >
Thanks for your review. Please find my response below. Fixed all the comments. I will update the next patchset. Thanks, Kumar. On Wed, Oct 13, 2021 at 8:16 AM Samuel Mendoza-Jonas <sam@mendozajonas.com> wrote: > 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. > Kumar : Yes. In the NC-SI spec, section 8.2.2.2 represents a 32-bit boundary. If it does not end on a 32-bit boundary, padding bytes can be added. > > 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? > Kumar : We have a use case of NIC firmware update in our system which is pldm based and the transport layer is NC-SI based on RBT. Sending some pldm based commands to NIC. In that, some of the commands failed because of a payload size less than 32. So, Added padding bytes to align the 32-bit boundary and issues got resolved. > > 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 > > > > > >
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);
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(-)