[PATCH] Fix vlan networking on little-endian systems

[PATCH] Fix vlan networking on little-endian systems

[Chad Kimes]

Vlan configuration seems to have never worked on little-endian systems. This is
likely because VLANTAG_IDENTIFIER is not byte-swapped before copying into the
net buffer, nor is vlantag. We can resolve this by using grub_cpu_to_be16 and
its inverse when copying vlan info to/from the net buffer.
---
 grub-core/net/ethernet.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/grub-core/net/ethernet.c b/grub-core/net/ethernet.c
index 4d7ceed6f..e49ccc940 100644
--- a/grub-core/net/ethernet.c
+++ b/grub-core/net/ethernet.c
@@ -58,7 +58,7 @@ send_ethernet_packet (struct grub_net_network_level_interface *inf,
   struct etherhdr *eth;
   grub_err_t err;
   grub_uint8_t etherhdr_size;
-  grub_uint16_t vlantag_id = VLANTAG_IDENTIFIER;
+  grub_uint16_t vlantag_id = grub_cpu_to_be16 (VLANTAG_IDENTIFIER);
 
   etherhdr_size = sizeof (*eth);
   COMPILE_TIME_ASSERT (sizeof (*eth) + 4 < GRUB_NET_MAX_LINK_HEADER_SIZE);
@@ -93,8 +93,9 @@ send_ethernet_packet (struct grub_net_network_level_interface *inf,
                    (char *) nb->data + etherhdr_size - 6, 2);
 
       /* Add the tag in the middle */
+      grub_uint16_t vlan = grub_cpu_to_be16 (inf->vlantag);
       grub_memcpy ((char *) nb->data + etherhdr_size - 6, &vlantag_id, 2);
-      grub_memcpy ((char *) nb->data + etherhdr_size - 4, (char *) &(inf->vlantag), 2);
+      grub_memcpy ((char *) nb->data + etherhdr_size - 4, &vlan, 2);
     }
 
   return inf->card->driver->send (inf->card, nb);
@@ -118,9 +119,9 @@ grub_net_recv_ethernet_packet (struct grub_net_buff *nb,
   /* Check if a vlan-tag is present. If so, the ethernet header is 4 bytes */
   /* longer than the original one. The vlantag id is extracted and the header */
   /* is reseted to the original size. */
-  if (grub_get_unaligned16 (nb->data + etherhdr_size - 2) == VLANTAG_IDENTIFIER)
+  if (grub_get_unaligned16 (nb->data + etherhdr_size - 2) == grub_cpu_to_be16 (VLANTAG_IDENTIFIER))
     {
-      vlantag = grub_get_unaligned16 (nb->data + etherhdr_size);
+      vlantag = grub_be_to_cpu16 (grub_get_unaligned16 (nb->data + etherhdr_size));
       etherhdr_size += 4;
       /* Move eth type to the original position */
       grub_memcpy((char *) nb->data + etherhdr_size - 6,
-- 
2.25.1

Re: [PATCH] Fix vlan networking on little-endian systems

[Daniel Kiper]

On Tue, Mar 01, 2022 at 11:18:52AM -0500, Chad Kimes via Grub-devel wrote:
> Vlan configuration seems to have never worked on little-endian systems. This is
> likely because VLANTAG_IDENTIFIER is not byte-swapped before copying into the
> net buffer, nor is vlantag. We can resolve this by using grub_cpu_to_be16 and
> its inverse when copying vlan info to/from the net buffer.

Please add your Signed-off-by tag here.

> ---
>  grub-core/net/ethernet.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/grub-core/net/ethernet.c b/grub-core/net/ethernet.c
> index 4d7ceed6f..e49ccc940 100644
> --- a/grub-core/net/ethernet.c
> +++ b/grub-core/net/ethernet.c
> @@ -58,7 +58,7 @@ send_ethernet_packet (struct grub_net_network_level_interface *inf,
>    struct etherhdr *eth;
>    grub_err_t err;
>    grub_uint8_t etherhdr_size;
> -  grub_uint16_t vlantag_id = VLANTAG_IDENTIFIER;
> +  grub_uint16_t vlantag_id = grub_cpu_to_be16 (VLANTAG_IDENTIFIER);

s/grub_cpu_to_be16/grub_cpu_to_be16_compile_time/

>    etherhdr_size = sizeof (*eth);
>    COMPILE_TIME_ASSERT (sizeof (*eth) + 4 < GRUB_NET_MAX_LINK_HEADER_SIZE);
> @@ -93,8 +93,9 @@ send_ethernet_packet (struct grub_net_network_level_interface *inf,
>                     (char *) nb->data + etherhdr_size - 6, 2);
>
>        /* Add the tag in the middle */
> +      grub_uint16_t vlan = grub_cpu_to_be16 (inf->vlantag);
>        grub_memcpy ((char *) nb->data + etherhdr_size - 6, &vlantag_id, 2);
> -      grub_memcpy ((char *) nb->data + etherhdr_size - 4, (char *) &(inf->vlantag), 2);
> +      grub_memcpy ((char *) nb->data + etherhdr_size - 4, &vlan, 2);
>      }
>
>    return inf->card->driver->send (inf->card, nb);
> @@ -118,9 +119,9 @@ grub_net_recv_ethernet_packet (struct grub_net_buff *nb,
>    /* Check if a vlan-tag is present. If so, the ethernet header is 4 bytes */
>    /* longer than the original one. The vlantag id is extracted and the header */
>    /* is reseted to the original size. */
> -  if (grub_get_unaligned16 (nb->data + etherhdr_size - 2) == VLANTAG_IDENTIFIER)
> +  if (grub_get_unaligned16 (nb->data + etherhdr_size - 2) == grub_cpu_to_be16 (VLANTAG_IDENTIFIER))

Ditto.

>      {
> -      vlantag = grub_get_unaligned16 (nb->data + etherhdr_size);
> +      vlantag = grub_be_to_cpu16 (grub_get_unaligned16 (nb->data + etherhdr_size));
>        etherhdr_size += 4;
>        /* Move eth type to the original position */
>        grub_memcpy((char *) nb->data + etherhdr_size - 6,

Daniel

Re: [PATCH] Fix vlan networking on little-endian systems

[John Paul Adrian Glaubitz]

Hello Chad!

On 3/1/22 15:03, Chad Kimes via Grub-devel wrote:
> The interface vlantag appears to have never worked on little-endian systems. This small
> initial patch is mostly to get my feet wet in the GRUB dev process. Once this is accepted,
> I intend to submit a few more patches that (a) allow vlan configuration via a command from
> the net module and (b) auto-configure vlan from the UEFI device used for PXE booting.

Could you use git send-email to send in your patches? See this guide, for example. [1]

Adrian

> [1] https://www.freedesktop.org/wiki/Software/PulseAudio/HowToUseGitSendEmail/

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz@debian.org
`. `'   Freie Universitaet Berlin - glaubitz@physik.fu-berlin.de
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913

[PATCH] Fix vlan networking on little-endian systems

[Chad Kimes]

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The interface vlantag appears to have never worked on little-endian
systems. This small initial patch is mostly to get my feet wet in the GRUB
dev process. Once this is accepted, I intend to submit a few more patches
that (a) allow vlan configuration via a command from the net module and (b)
auto-configure vlan from the UEFI device used for PXE booting.


diff --git a/grub-core/net/ethernet.c b/grub-core/net/ethernet.c
index 4d7ceed6f..e49ccc940 100644
--- a/grub-core/net/ethernet.c
+++ b/grub-core/net/ethernet.c
@@ -58,7 +58,7 @@ send_ethernet_packet (struct
grub_net_network_level_interface *inf,
   struct etherhdr *eth;
   grub_err_t err;
   grub_uint8_t etherhdr_size;
-  grub_uint16_t vlantag_id = VLANTAG_IDENTIFIER;
+  grub_uint16_t vlantag_id = grub_cpu_to_be16 (VLANTAG_IDENTIFIER);

   etherhdr_size = sizeof (*eth);
   COMPILE_TIME_ASSERT (sizeof (*eth) + 4 < GRUB_NET_MAX_LINK_HEADER_SIZE);
@@ -93,8 +93,9 @@ send_ethernet_packet (struct
grub_net_network_level_interface *inf,
                    (char *) nb->data + etherhdr_size - 6, 2);

       /* Add the tag in the middle */
+      grub_uint16_t vlantag = grub_cpu_to_be16 (inf->vlantag);
       grub_memcpy ((char *) nb->data + etherhdr_size - 6, &vlantag_id, 2);
-      grub_memcpy ((char *) nb->data + etherhdr_size - 4, (char *)
&(inf->vlantag), 2);
+      grub_memcpy ((char *) nb->data + etherhdr_size - 4, &vlantag, 2);
     }

   return inf->card->driver->send (inf->card, nb);
@@ -118,9 +119,9 @@ grub_net_recv_ethernet_packet (struct grub_net_buff *nb,
   /* Check if a vlan-tag is present. If so, the ethernet header is 4 bytes
*/
   /* longer than the original one. The vlantag id is extracted and the
header */
   /* is reseted to the original size. */
-  if (grub_get_unaligned16 (nb->data + etherhdr_size - 2) ==
VLANTAG_IDENTIFIER)
+  if (grub_get_unaligned16 (nb->data + etherhdr_size - 2) ==
grub_cpu_to_be16 (VLANTAG_IDENTIFIER))
     {
-      vlantag = grub_get_unaligned16 (nb->data + etherhdr_size);
+      vlantag = grub_be_to_cpu16 (grub_get_unaligned16 (nb->data +
etherhdr_size));
       etherhdr_size += 4;
       /* Move eth type to the original position */
       grub_memcpy((char *) nb->data + etherhdr_size - 6,

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