@@ -320,7 +320,15 @@ grub_efinet_findcards (void)
card->name = grub_xasprintf ("efinet%d", i++);
card->driver = &efidriver;
- card->flags = 0;
+ /*
+ * EFI network devices are abstract SNP protocol instances, and the
+ * firmware is in charge of ensuring that they will be torn down when the
+ * OS loader hands off to the OS proper. Closing them as part of the
+ * preboot cleanup is therefore unnecessary, and undesirable, as it
+ * prevents us from using the network connection in a protocal callback
+ * such as LoadFile2 for initrd loading.
+ */
+ card->flags = GRUB_NET_CARD_NO_CLOSE_ON_FINI_HW;
card->default_address.type = GRUB_NET_LINK_LEVEL_PROTOCOL_ETHERNET;
grub_memcpy (card->default_address.mac,
net->mode->current_address,
@@ -1787,7 +1787,7 @@ grub_net_fini_hw (int noreturn __attribute__ ((unused)))
{
struct grub_net_card *card;
FOR_NET_CARDS (card)
- if (card->opened)
+ if (card->opened && !(card->flags & GRUB_NET_CARD_NO_CLOSE_ON_FINI_HW))
{
if (card->driver->close)
card->driver->close (card);
@@ -64,7 +64,8 @@ typedef enum grub_net_interface_flags
typedef enum grub_net_card_flags
{
GRUB_NET_CARD_HWADDRESS_IMMUTABLE = 1,
- GRUB_NET_CARD_NO_MANUAL_INTERFACES = 2
+ GRUB_NET_CARD_NO_MANUAL_INTERFACES = 2,
+ GRUB_NET_CARD_NO_CLOSE_ON_FINI_HW = 4
} grub_net_card_flags_t;
struct grub_net_card;
When GRUB runs on top of EFI firmware, it only has access to block and network device abstractions exposed by the firmware, and it is up to the firmware to quiesce the underlying hardware when handing over to the OS. This is especially important for network devices, to prevent incoming packets from being DMA'd straight into memory after the OS has taken over but before it has managed to reconfigure the network hardware. GRUB handles this by means of the grub_net_fini_hw() preboot hook, which is executed before calling into the booted image. This means that all network devices disappear or become inoperable before the EFI stub executes on EFI targeted builds. This is problematic as it prevents the EFI stub from calling back into GRUB provided protocols such as LoadFile2 for the initrd, which we will provide in a subsequent patch. So add a flag that indicates to the network core that EFI network devices should not be closed when grub_net_fini_hw() is called. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> --- grub-core/net/drivers/efi/efinet.c | 10 +++++++++- grub-core/net/net.c | 2 +- include/grub/net.h | 3 ++- 3 files changed, 12 insertions(+), 3 deletions(-)